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Evolution in Thermodynamics

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Abstract

This review covers two aspects of “evolution” in thermodynamics. First, with the constructal law, thermodynamics is becoming the domain of physics that accounts for the phenomenon of evolution in nature, in general. Second, thermodynamics (and science generally) is the evolving add-on that empowers humans to predict the future and move more easily on earth, farther and longer in time. The part of nature that thermodynamics represents is this: nothing moves by itself unless it is driven by power, which is then destroyed (dissipated) during movement. Nothing evolves unless it flows and has the freedom to change its architecture such that it provides greater and easier access to the available space. Thermodynamics is the modern science of heat and work and their usefulness, which comes from converting the work (power) into movement (life) in flow architectures that evolve over time to facilitate movement.

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... For biology, the CBET is more scientific and comprehensive than previous theories, because the CBET is deduced from laws of thermodynamics, and as given in for evolution and listed in Section 1, and they did not employ the simple expression of the second law of thermodynamics to explain evolution, and they did not reveal the driving force or mechanism in a direct and comprehensible way [44][45][46][47][48][49][50]. Although some notions or theories in thermodynamics, such as negative entropy (negentropy) and the dissipative structure theory, have been employed to explain evolution [44][45][46][47][48][49][50], as detailed in Supplementary File, these notions or theories are elusive, controversial, or even wrong, mainly because scientists were misled by the wrong notion that biological order is equal to thermodynamic order [44][45][46][47][48][49][50]. ...
... For biology, the CBET is more scientific and comprehensive than previous theories, because the CBET is deduced from laws of thermodynamics, and as given in for evolution and listed in Section 1, and they did not employ the simple expression of the second law of thermodynamics to explain evolution, and they did not reveal the driving force or mechanism in a direct and comprehensible way [44][45][46][47][48][49][50]. Although some notions or theories in thermodynamics, such as negative entropy (negentropy) and the dissipative structure theory, have been employed to explain evolution [44][45][46][47][48][49][50], as detailed in Supplementary File, these notions or theories are elusive, controversial, or even wrong, mainly because scientists were misled by the wrong notion that biological order is equal to thermodynamic order [44][45][46][47][48][49][50]. ...
... For biology, the CBET is more scientific and comprehensive than previous theories, because the CBET is deduced from laws of thermodynamics, and as given in for evolution and listed in Section 1, and they did not employ the simple expression of the second law of thermodynamics to explain evolution, and they did not reveal the driving force or mechanism in a direct and comprehensible way [44][45][46][47][48][49][50]. Although some notions or theories in thermodynamics, such as negative entropy (negentropy) and the dissipative structure theory, have been employed to explain evolution [44][45][46][47][48][49][50], as detailed in Supplementary File, these notions or theories are elusive, controversial, or even wrong, mainly because scientists were misled by the wrong notion that biological order is equal to thermodynamic order [44][45][46][47][48][49][50]. ...
Preprint
It is desirable to upgrade previous evolutionary theories, which have remained incomplete and controversial for decades. Here we employ the concept of carbon-based entities (CBEs), which include methane, amino acids, proteins, organisms, and other entities containing relatively many carbon atoms. We deduce the driving force, mechanisms, steps, modes, tempos of CBE evolution, through integration of biology, physics, and chemistry using logics for complex issues. We hence establish the Carbon-Based Evolutionary Theory (CBET). The CBET suggests that evolution is the increase in hierarchy, diversity, fitness of CBEs under natural selection and driven by thermodynamics due to the chemical effect of the thermodynamic features of the Earth on CBEs. It provides better explanations for life origin, macroevolution events, natural selection, sympatric speciation, and evolution tempos than previous evolutionary theories. It reveals the evolutionary basis of multiple important social notions, including diversity, collaboration, altruism, obeying rules, and proper increase in freedom. It refutes some wrong notions in thermodynamics, including negative entropy (negentropy) and that biological order is equal to thermodynamic order, which have misled many people. The CBET is supported by its deduction and application. It could be a rare bridge linking laws of thermodynamics, evolution of life, and development of human society, and could have great significance in various sciences.
... The generation of power from fire and other sources (natural, animal and human) happened because of designs with evident purpose: to move things against the steadfast opposition posed by the ambient. This is true about thermodynamics in all its domains of application, from animals (physiology, locomotion) to all the designs driven by the earth engine (atmosphere, hydrosphere, lithosphere, volcanos and hurricanes) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. ...
... Natural convection phenomena are extremely common examples of engine & brake systems at all scales, in the atmosphere and the hydrosphere. The evolution of any flow configuration that has freedom to morph is accounted for by an additional first principle, the constructal law [1,2], Energies 2021, 14, 408 8 of 25 Figure 9. Thermodynamics now accounts for phenomena of configuration and evolution, in addition to the phenomena that before 1851 were covered separately by mechanics theory and caloric theory. During the past two decades the use of the constructal law spread, and its predictive power cleared up puzzles that were persisting in science. ...
... Yet, the field of applications is much broader: the subject of "fire" is the chemical thermodynamics (combustion), the drainage basin ( Figure 11) is the earth thermodynamics, and the vascular design ( Figure 12) is the animal design. This broad applicability is how our review began (cf, references [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]), and note that "purpose" is very much a topic in biology today. Figure 12. ...
Article
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This is a review of the concepts of purpose, direction, and objective in the discipline of thermodynamics, which is a pillar of physics, natural sciences, life science, and engineering science. Reviewed is the relentless evolution of this discipline toward accounting for evolutionary design with direction, and for establishing the concept of purpose in methodologies of modeling, analysis, teaching, and design optimization. Evolution is change after change toward flow access, with direction in time, and purpose. Evolution does not have an ‘end’. In thermodynamics, purpose is already the defining feature of methods that have emerged to guide and facilitate the generation, distribution, and use of motive power, heating, and cooling: thermodynamic optimization, exergy-based methods (i.e., exergetic, exergoeconomic, and exergoenvironmental analysis), entropy generation minimization, extended exergy, environomics, thermoecology, finite time thermodynamics, pinch analysis, animal design, geophysical flow design, and constructal law. What distinguishes these approaches are the purpose and the performance evaluation used in each method.
... However, there are still some different viewpoints on the application of the entransy theory. Several researchers published negative viewpoints [39][40][41][42] without referring the replies [43][44][45][46]. The logic of these publications [39][40][41][42] is not consistent. ...
... Several researchers published negative viewpoints [39][40][41][42] without referring the replies [43][44][45][46]. The logic of these publications [39][40][41][42] is not consistent. Some negative comment papers included misreading of the original definition [39], misunderstanding of physical basis of entransy [42] and even personal attacks [39]. ...
... The logic of these publications [39][40][41][42] is not consistent. Some negative comment papers included misreading of the original definition [39], misunderstanding of physical basis of entransy [42] and even personal attacks [39]. These comments have already been replied [43][44][45][46] and will not be discussed here. ...
Article
Full-text available
The entransy theory is widely used and found to be effective in thermal analyses and optimizations. Some researchers considered the entransy variation due to viscous heating as part of entransy dissipation and analyzed convective heat transfer based on the differential relationship between entropy and entransy. However, it has been pointed out that the derivation of the differential relationship between entropy and entransy is incorrect. In this paper, the convective heat transfer processes with viscous heating is reconsidered and analyzed from theviewpoint of the energy conservation and the entransy balance equation. It is shown that the influence of the viscous heating is equivalent to that of an inner heat source. Therefore, the contribution of viscous heating to system entransy should not be treated as part of entransy dissipation, but entransy flow into the system. Two-stream parallel and counter flow heat exchangers with viscous heating and a thermal insulation transportation problem of heavy oil are taken as examplesto verify the theoreticalanalyses intuitively.In the examples, thenumerical results show that the entransy dissipation rates could be negative when the influence of the viscous heating on the system entransy is treated as part of the entransy dissipation. This is obviously unreasonable. Meanwhile, when the entransy contribution from the viscous heating to the system entransy is treated as entransy flow into the system, it is shown that the entransy dissipation rate is alway spositive, and the heat transfer processes can be well explained with the entransy theory.
... Here are just a few of the examples that I detailed in Refs. [1][2][3][4]: ...
... It is true that during the birth of thermodynamics ( Figure 1) the system contemplated by the pioneers was closed: the heat engine operating in cycles or in steady state while in communication with two temperature reservoirs ( Figure 2). The laws were generalized for open systems in the late 1800s [2,7]. ...
... The sources for the timeline are available in Refs. [2,7]: 1850-1851, the first papers by Rankine, Clausius and Kelvin; 1982, the first book on entropy generation through heat and fluid flow [10]; 1996, the first papers on constructal law. The first version of this figure appeared in 1982 [10]. ...
Article
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Thermodynamics is a discipline, with unambiguous concepts, words, laws and usefulness. Today it is in danger of becoming a Tower of Babel. Its key words are being pasted brazenly on new concepts, to promote them with no respect for their proper meaning. In this brief Perspective, I outline a few steps to correct our difficult situation.
... Usually, to analyse the metabolic machine operating process in a realistic configuration-hence addressing the whole biological system, one needs to successively: (i) express the local energy budget; (ii) integrate the local expressions over the spatial variables; (iii) explicitly include the boundary conditions. While thermodynamic models of biological systems have been extensively developed [1][2][3][4][5][6][7][8][21][22][23], including the thermodynamic network approach and bond-graph methods [24,25], a proper account of the above three points is often missing, leading to an incomplete thermodynamic description of the biological energy conversion. Our abstract approach, on the contrary, facilitates the treatment of these quite concrete aspects. ...
... Thermodynamics provides the proper framework to describe and analyse the rich variety of existing sources of energy and the processes allowing its conversion from one form to another. Yet, of all known energy converters, man-made or not, living organisms still represent a formidable challenge in terms of thermodynamic modeling, due to their high complexity which far exceeds that of any other artificial or natural system [1][2][3][4][5][6][7][8] . Energy conversion in living bodies is driven by metabolism, which ensures through chemical reactions at the cellular level, and along with other vital functions, the provision of heat necessary to maintain a normal body temperature, as well as, to a lesser extent, the energy required for muscular effort and motion. ...
... In other words, the animal metabolism is in the short-circuit configuration, fully loaded, and the metabolic intensity density J M reaches a critical value J X at the exhaustion stage. Then, from equation (8), the associated energy flux, denoted J Em † , under the zero mechanical condition is: ...
Experiment Findings
Full-text available
Oxygen ventilation
... Biological systems, such as vascular networks [1], hyphal networks [2,3], neurons [1,4], slime molds [5], and bacterial colonies [6], display complex structures rich in branched or tree-like spatial features. The morphology of these systems seem to solve an adaptive exploration problem related to the maximization of the space that a connected structure can cover in order to retain or gain conditions for survival given limited amounts of matter, energy and information, and according to the demands and restrictions of the environment [7,8,9,10]. ...
... A good understanding of the fundamental physical, chemical, and biological aspects behind the development of such systems could provide valuable insights into fields such as medicine (e.g. cancer) [1,12,38], engineering and technology [9,39,40], biomimetic materials [41], and the design of sustainable cities and transportation systems [5,42,43]. ...
Preprint
Full-text available
Biological systems with tree-like morphological features emerge as nature's solution to an adaptive spatial exploration problem. The morphological complexity of these systems is often described in terms of its fractality, however, the network topology plays a relevant role behind the system's biological function. Therefore, here we considered a structural analysis of bio-inspired spatial systems based on fractal and network approaches in order to identify the features that could make tree-like morphologies better at exploring space under limited matter, energy and information. We considered connected clusters of particles in two-dimensions: the Ballistic and Diffusion-Limited Aggregation stochastic fractals, the Viscek and Hexaflake deterministic fractals, and the Kagome and Hexagonal lattices. We characterized their structure in terms of the range (linear extension), coverage (plane-filling), cost (assembly connections), configurational complexity (local connectivity), and efficiency (network communication). We found that tree-like systems have a lower configurational complexity and an invariant structural cost for different fractal dimensions, however, they are also fragile and inefficient. Nevertheless, this efficiency can become similar to that of an hexagonal lattice, at a similar cost, by considering euclidean connectivity beyond first neighbors. These results provide relevant insights into the interplay between the morphological and network properties of complex spatial systems.
... The CBEET hence bridges physics, biology, and social sciences. Moreover, the CBEET refutes thoroughly the wrong notion of negative entropy (negentropy) which has widely skewed sciences for decades [41][42][43][44][45][46][47], as detailed in Supplementary Notes. ...
... Sixth, under certain inherent mechanisms, some high-entropy systems, such as organisms, choruses, armies, airplanes, and skyscrapers, can demonstrate some kinds of order, which is distinct from the cold, low-entropy and crystal-like thermodynamic order (Box 1). Seventh, lives rely on entropy rather than negentropy, because lives rely on movement rather than immobilization of their inner components [45]. Ludwig Boltzmann, who created the Boltzmann formula of entropy, also pointed that animate beings struggle for entropy which becomes available through the transition of energy from the hot sun to the cold earth [46]. ...
Preprint
The current evolutionary theories have remained incomplete, controversial, and stagnant for multiple decades. To solve this issue, we create the concept of carbon-based entities (CBEs) which include methane, amino acids, proteins, organisms, and other entities containing carbon atoms. We deduce from thermodynamics the driving force, the progressive mechanisms, and the major steps of evolution of CBEs, and hence establish a comprehensive evolutionary theory termed the CBE evolutionary theory (CBEET). The CBEET demonstrates that evolution is driven hierarchy-wise by thermodynamics and favors fitness and diversity. It provides novel explanations for origin of life (abiogenesis), macroevolution, natural selection, sympatric speciation, evolution tempos, animal group evolution, and human society development in a comprehensive and comprehensible way. It elucidates that collaboration, altruism, obeying rules with properly increased freedom are important throughout evolution of CBEs. It refutes thoroughly the wrong notion that negative entropy (negentropy) leads to biological order which is distinct from thermodynamic order. It integrates with research advances in multiple disciplines and bridges laws of physics, evolution in biology, and harmonious development of human society.
... The Constructal Principle has been proposed by Adrian Bejan in 1997(Bejan, 1997 and then it has been used in literature to predict the shape and structure for a lot of physical flow systems (Bejan and Lorente, 2013;Bejan, 2017;Bejan and Errera, 2017;. It is often regarded as a possible 4th Law of Thermodynamics, stating the direction toward which a system evolves if it has access to some external resources to feed its internal fluxes, i.e., if it can stay far from equilibrium with its surrounding. ...
... the network. Therefore, the CL may be applied to the extended energy system as well as it has been applied in literature to a lot of physical flow systems, like river basins, sap ducts inside trees, pulmonary ducts, heat exchangers and so on (see, for instance, Ref. Bejan and Lorente, 2013;Bejan, 2017;Bejan and Errera, 2017;. ...
Article
Full-text available
The aim of the paper is to identify the consequence of the Constructal Principle in the field of Thermoeconomics of (energy) production systems. This Principle has been recently formulated as an extension of the Maximum Entropy Production Principle and it has been used in literature to explain the shape and structure of all kind of flowing systems. First, the concept of Thermoeconomic Environment is defined consistently with the consumption of environmental resources and residual emissions, which inherently characterize every kind of production system. This approach allows to infer that the evolution of any energy system is strictly related to the exploitation of resources from the Thermoeconomic Environment. Moreover, the widely accepted assumption that energy systems have to be optimized by minimizing the specific resource (exergy) cost of products, has to be regarded as a consequence of a physical principle that tells us which energy systems can persist in time (to survive) and which others would be selected for extinction. The paper shows how the creation of a recycle may allow a reduction of the unit exergy cost of the product, obtaining a more sustainable behavior of the macro-system, made up by the production process together with its supply chains, consistently with the Constructal Principle. Finally, the definition of the Thermoeconomic Environment allows (at least in principle) to properly identify the resource (exergy) cost of disposing off residues and sub-products directly in the environment, without any kind of additional operation. As a consequence, residues and sub-products have to be generally converted into some kind of product by different (new) production processes, supporting the paradigm of the Circular Economy and highlighting the importance of recycling not only for system efficiency, but for system surviving. More generally, the results obtained may be regarded as the physical justifications of the evolutionary tendency toward the more and more complex and highly circular pathways that can be observed in both natural and artificial (energy) production systems.
... The related negative comments have already been replied [125,126]. However, these replies were ignored, and the negative comments were repeated and published time and time again [127][128][129][130][131][132][133][134][135][136][137]. Especially, Awad [129][130][131][132][133] published quite a few comments of this kind by repeating although he wrote that "Repetition does not mean refutation". ...
... Professor Guo engaged lawyers to deal with these slanders and personal attack [108]. Afterwards, a conciliation settlement had been [123,145,146], renaming the physical base of the theory and trying to deny the classical analogy between electric conduction and heat conduction [123,128,135,137]. Correspondingly, these doubts and negative comments were also replied with scientific facts and peaceful discussions [78,[140][141][142][143][144]146]. ...
Chapter
In engineering, there are different design objectives for heat pump systems, such as the maximum coefficient of performance, the maximum net heat flow rate into the high temperature heat source and the best thermo-economic performance. As such, the authors provide a comprehensive overview of heat pump technology, focusing on system design, performance, optimization and applications associated with this technology. Following this, a research study on the optimal operation of a power system in the presence of renewable sources is presented, considering two objectives: decreasing power losses and improving the voltage level in the nodes of the electric network. A method for detecting short-path wormhole tunnels rather than relying solely on topological features of the network is described. In a wormhole attack, the malicious nodes generally work in pairs and set up a high-speed tunnel for long distances between them. An approach to multi-objective optimization techniques is presented and applied to either subtractive or additive manufacturing processes. Additionally, the suitability of multi-objective optimization methods is depicted through a case study related to the selective laser melting process. The performance evaluation of the binary heap tree-based discrete particle swarm optimization is presented and compared with existing Pareto dominance-based multi-objective techniques such as non-dominated sorting genetic algorithm-II and non-dominated sorting particle swarm optimization. In closing, the authors present a problem that highlights the influence that bidirectional power flows may have on solutions regarding the optimal allocation of energy storage systems in real microgrids in the developing country of Romania.
... Notice that Bejan does not see his "law" as a simple consequence of the Second Law, but rather as its logical cause: "The constructal law accounts for the universal phenomenon of generation and evolution of design (configuration, shape, structure, pattern, rhythm)" [4]. He regards CT as the confluence of Thermodynamics and Evolution that leads to "the thermodynamics of nonequilibrium systems with configuration" [3]. CT becomes thus a metaparadigm of Thermodynamics, a prime principle that cannot be demonstrated but that has been, in the words of its discoverer, "induced" from observation just like, 150 years earlier, the classical laws of Thermodynamics had. ...
... Such an axiomatic character has both advantages and weaknesses: the purported "universal generality" of CT leads indeed to the identification of "similar" shapes (configurations) in the most [16]. 2 As remarked above, Bejan's 1996e97 formulation of the Constructal Theory [2] can be seen as a generalization of the HM law: he reasoned that, if the law holds, every bifurcated stream that carries a material or immaterial flow from one point to two (or more) others in a given domain should -in an evolutionary sense-develop into a structure exactly specified by the "cubic root of 2 À1/3 rule, complemented by additional constraints based on minimum volume/minimum weight. 3 This should come to no surprise: already in a 1809 lecture paper, Thomas Young [26] remarked that the 2 À1/3 rule can be derived from the assumption of a constant wall stress in a viscous laminar flow. ...
Article
Bifurcated flows are ubiquitous in nature. Their being such a common feature of many natural “structures” has prompted a multitude of investigations in diverse scientific branches: botanists, neurophysicians, biologists and chemists have attempted to find a “structural plan” on which to build a general model of the formation and evolution of bifurcations. Not incidentally, the engineering side of the issue is also extremely interesting: from heat exchangers to pipelines to district heating networks, the existence of a “general geometric model” would much facilitate a designer’s life. The study reported in this paper is based on a straightforward application of the exergy cost theory to the development and self-sustenance of natural bifurcated structures and leads to the conclusion that the shape, connectivity and evolution of a dycotomic depend on several factors that are irreducibly case dependent. This result is of great importance for engineered bifurcations, for which the same impossibility to generalize is again demonstrated: here though, since the “design goals” are formulated as rather simple constraints (simpler than in nature!), a somewhat larger degree of (albeit always application-dependent) generality is found. The exergy cost method is valid for any virtual or real system, and assigns a “resource cost” to its products: it consists in evaluating the exergy inflows (in W) and in keeping an accurate bookkeeping of the embodied exergy (in W/kg or W/m³) into the system, to calculate an average (instantaneous or lifetime-based) exergy input. The cost is then obtained by dividing this “cumulative input” by the exergy flux of the “products” in the same time window. In natural processes, this cost is called the Exergy Footprint, because it represents the actual primary resource consumption necessary to generate the outputs. In engineered artifacts, an additional procedure can be used to internalize the externalities (Labour, Capital and Environmental Remediation cost) so that the total equivalent primary exergy consumption needed to generate a unit of “product” can be again applied as a cost indicator. The novelty of the method and of the results discussed in this paper is twofold: first, the two most popular bifurcation models (Fractal and Constructal) are critically re-evaluated to show that neither one succeeds in generating credible predictive correlations. Second, it is demonstrated that the exergy costing paradigm provides a feasible and rigorous method for identifying the optimal bifurcation geometry for practical engineering applications. To express the results in a concise sentence: it is indeed possible to accurately and rigorously predict the optimal shape of a bifurcated structure once its function is known, but at the loss of generality. Neither in nature nor in engineering sciences bifurcated flows can be optimized by a universally valid allometric rule.
... In view of equations (6.2) and (6.3), the only possible explanation for the mathematical form appearing on the right side of equation (6.1) is the presence of an external system (a heater) that delivers heat transfer (δQ) in proportion not only to the temperature increment (dT) experienced by the system, but also in proportion to the instantaneous temperature of the system (T). The unspoken assumption that leads to an expression such as equation (6.1) is this [44] ...
... False concepts are exposed, mistakes are corrected and this way a renewed appreciation of the discipline empowers the new generations. Students, researchers, authors, university administrators, funding agencies and national academies could learn from this [44]. ...
Article
Heat transfer is a mature science, and so is thermodynamics. They are almost 200 years old having developed largely independently until the 1980s. Maturity comes from the usefulness and success of the thermal sciences. This review uses the thermodynamics of heat transfer to focus on aspects that are usually not discussed in physics: performance, purpose, function, objective and direction of evolutionary design. The article illustrates the unity of the thermal sciences discipline (heat transfer + thermodynamics + constructal law), and uses the opportunity to correct a few recent interpretations of the thermodynamics of heat transfer regarding dissipative engines and energy storage. © 2019 The Author(s) Published by the Royal Society. All rights reserved.
... The tribological system is defined as a set of open control volumes [40]. We consider the two first bodies, the third body and a fourth control volume that interfaces the third body and the environment ( Figure 3). ...
Article
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In the context of sustainable development and under the impulse of continuous technological progress, tribology contributes to the improvement of the life span of parts in dynamic contact and to the efficiency of mechanical systems. However, even if successes are obtained in lubrication, the tribology community struggles to build generalised laws of friction and wear in the case of dry friction. Based on the thermodynamics of open systems, we suggest an adaptation of the conservation of mass and energy equations to the tribosystem. The latter is modelled using the concepts of tribological triplet, tribological circuit and accommodation mechanisms. The tribosystem is described with four control volumes: two of them represent the first two bodies in dynamic contact; a third one is the tribofilm produced by the debris emission from the first bodies; a fourth control volume is used as an interface between the third body and the external environment. A mass balance is applied to these four control volumes by considering their interactions. An energy balance is then derived by applying the first principle of thermodynamics. Two systems of interdependent equations that describe the circulation of matter and energy flows in the tribosystem are outlined. These equations can be considered as a basis for future experimental developments that would aim at simultaneously characterising the different modes of energy dissipation in dynamic contact, qualitatively and especially quantitatively.
... Moreover, Rodrigues et al 1 and Brum et al 27 investigated, in accordance with Constructal Design, several configurations for the arrangement of parallel straight pipes (pair, triangular, rectangular, and diamond). Constructal Design method [28][29][30][31][32] is based on balancing constraints and degrees of freedom for evaluation of any animate or inanimate finite size flow systems. Constructal theory proved to be fully versatile and interdisciplinary, as it was used to demonstrate that even natural systems follow a physical principle of generation, configuration, and design evolution. ...
Article
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Significant advancements in developing earth‐air heat exchanger models have been detected in the past several decades. It is worth mentioning that this type of device takes advantage of the Earth's constant temperature to cool or heat spaces in buildings so that the identification of its most appropriate geometric configurations to reduce energy consumption is still an actual challenge. In this context, the present paper is focused on the geometric evaluation of several earth‐air heat exchangers arrangements according to the Constructal Design method. The performance indicators are the minimization of its soil volume occupation, the minimization of its airflow pressure drop, and the maximization of its thermal potential. Therefore, from a straight duct named Reference Installation, 26 complex geometries have been outlined here using the numerical‐analytical investigation. Many ideas emerged from this study: the use of serpentine with low spacing between ducts reduced nearly 39% of the soil volume occupied by the device compared to Reference Installation, showing its applicability in urban regions. In addition, configurations with few curves benefited the decrease of air pressure drop, allowing a performance 30% superior to the most complex shapes. Instead, complex designs can be recommended for thermal potential increase, although the influence of the different configurations over this indicator was not substantial since the maximum improvement achieved between the best and worst shapes proved to be around 6%. Finally, when the three performance indicators are concomitantly considered, several complex geometries reached an overall performance superior to the Reference Installation. Computational domain and boundary conditions of the EAHE model: a) schematic perspective view, b) top view (Plane A‐A) with dimensions of Reference Installation (RI). Module of the distance between performance indicator coordinate and an ideal hypotethical EAHE with VN = hN = (TPN)−1 = 0.
... Considering the available energy and available work as valuable commodities [122,123], it is evident the opportunity of a deeper analysis by involving the second law of thermodynamics [124,125] and concepts as entropy generation and exergy dissipation. The second law of thermodynamics [126,127] is expected to improve the results effectively. ...
Preprint
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This paper presents the heat and mass transfer model and the design analysis of ALCHEMIST (Atmospheric Laboratory for the study of Circulation at High-altitude, Exchange of Markers and Intercontinental routes between Stratosphere and Troposphere). It is an innovative hybrid balloon project. It is constituted by coupling an external unconventional parachute envelope and a Hydrogen balloon. The dynamic equilibrium conditions with the surrounding atmosphere are considered. The system has been modeled as a limited unsteady irreversible thermodynamic living system. The mission is considered as an evolution of the system in equilibrium with the surrounding environment. Hence, a thermodynamic model based on irreversible thermodynamics is presented. The results according to both first and second law are produced and compared to actual flight data. The primary physical processes responsible for balloon performance aloft are accurately modeled in the proposed optimization process. The results demonstrate that the system could be optimized up to a stratospheric altitude around 30 km and shows that second law optimization produces an effective performance improvement.
... Entropy allows understanding the efficiency of the physical, biological, and chemical processes and the associated dissipations, which can always be analyzed through the second law of thermodynamics [56,57]. This analysis accounts for Prigogine's results on dissipative structures [58 -60] and entropy in unsteady systems [61] and the thermodynamic model of evolution as stated by Bejan [62,63]. Natural and living systems are open systems that exchange heat and mass and interact with the environment. ...
Article
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Is it possible to characterize the SARS-CoV-2 viral infection by analyzing the viral hijacking of cellular metabolism for its reproduction and multiplication? Gibbs free energy appears to be the critical factor of successful virus infection. A virus always has a more negative Gibbs free energy of growth than its host. Hence, the synthesis of viral components is thermodynamically favourable. On the other side, it could be essential to better thermodynamically understand how S1 and S2 spike protein interacts with the ACE2 receptors and the cell membrane more efficiently than the usual nutrients, which are intercepted. Gibbs energy gives a static model, which does not include the time arrow of viral evolution. A better comprehension of this evolutional path could require an accurate analysis of entropy generation or exergy disruption of binding, replication, and multiplication.
... Bejan (2007) also argued that global ocean and atmospheric circulation reflects the constructal law. A direct, explicit link exists between evolution/selection and thermodynamics, Bejan (2017) argues, such that thermodynamic systems (essentially, all systems that move or change) evolve. Constructal-type behavior arises from traditional path of least resistance reasoning if selection results in persistence of the preferred flow paths. ...
Chapter
Darwinian natural selection acting on individuals is one of only several types of selection influencing landscape evolution. Ecological filtering and abiotic selection (including the least action principle and preferential flows) apply. The overarching principle is one of efficiency selection, whereby more efficient, stable, and durable forms, structures, patterns, networks, and flux pathways are more likely to occur, grow, and persist than less efficient ones. Particularly important forms are gradient selection, favoring steeper and faster flow paths; resistance selection, whereby more resistant features are preferentially preserved; biogeochemical selection, which favors more rapid elemental cycling; network selection, which makes more efficient flux and interaction networks more likely; and thermodynamic selection, reflecting the advantages of energy use efficiency. Efficiency selection is highly local, however, one of several reasons that landscapes and environmental systems are not always inevitably becoming more efficient overall. A case study illustrating selection principles is given.
... In the past years, the new concept of entransy developed under controversies as some scholars confused with entropy and entransy [41]. Nevertheless, the controversies have been clarified and the entransy concept was considered to be inherently suited for the evaluation and optimization of heat transfer processes [42]. ...
Article
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The heat transfer during air cooling of postharvest produce tends to be heterogeneous using either room cooling or forced-air cooling due to airflow maldistribution. The heterogeneity is typically evaluated in terms of temperature. In this study, the thermodynamic indicators, including the rates and the temporal cumulation of entropy generation and entransy dissipation, are proposed for heterogeneity analysis. Based on the experiments with postharvest apples, the heterogeneity is compared between air cooling methods using the proposed thermodynamic indicators. The temporal variation tendencies and spatial distribution characteristics of these thermodynamic indicators are further discussed. Higher heat transfer heterogeneity regarding to the rates of entropy generation and entransy dissipation is observed at the beginning stage and at the end of the process with lower temperature heterogeneity. In comparison with the entropy generation, the entransy dissipation is more appropriate for heterogeneity comparison because of the consistency. The cumulative entransy dissipation is generally higher at the locations with more airflow and higher heat transfer rate. When compared with room cooling, the consistent reduction of standard deviation and coefficient of variation for the cumulative entransy dissipation indicates overall lower heat transfer heterogeneity for forced-air cooling.
... The new and efficient systems need to be evolved by replacing the old and inefficient ones, which is central focus of the constructal theory. The constructal theory of Prof. A. Bejen [30][31][32][33][34][35][36] primarily focuses on the evolution of animate and inanimate objects for their existence with the time. The popularization of this theory is clearly evident from its wide applications to various engineering systems-the systems for storing thermo-chemical [37,38] and latent energy [39], heat recovery in steam generators (HRSGs) [40], ammonia-water system [41], H-shaped heat exchangers [42,43], radiant cooling panels [44], the maximization of heat transfer density for parallel plates [45] and spheres [46] in cross-flow, Ocean thermal energy conversion system [47], X-shaped networks [48,52], design of the super-heater of a supercharged boiler [49], heat transfer enhancement for a forked-shaped fins [50], triangular-heat-generating element [51] and many more. ...
Article
In this paper, the constructal theory has been applied to evolve six new types of ribs (T-rib, left arm inclined T-rib, right arm inclined T-rib, Y-rib, concave and convex T-ribs) for a solar air heater (SAH). The fluid flow and heat transfer characteristics of the SAH with these ribs have been numerically investigated by solving the mass, momentum, energy, and turbulence equations employing the finite volume technique of ANSYS Fluent R16. The SST k − ωmodel has been used to solve the turbulence quantities, especially, the turbulent kinetic energy (k), and the specific dissipation rate (ω). The performance of the SAH has been obtained by varying different prominienet parameters of importance, such as the pitch (20 mm-90 mm), stem height (3 mm-11 mm), the inclination angle of the rib (0 o-60 •) and Reynolds number (5000-18,000). The optimal lengths for the pitch (i.e., 80 mm) and for the stem height (i.e., 8 mm) have been found out for T-ribs. It has been observed that the Nusselt number for T-rib increases by 191% in a range of Reynolds number, 5000-18,000, and at the optimum pitch and stem height. It is also observed that the Nusselt number marginally increases with the inclination angle of the rib. The concave T-rib and convex T-ribs have been evolved from the basic T-rib. Among all the considered ribs, the T-rib is found to be the best heat transfer enhancer keeping the friction factor at a low value. We found a higher Nusselt number and a lower friction factor for the present SAH with the T-ribs, as compared to that of the SAHs considered by previous researchers. The thermo-hydraulic performance (THPP) of a SAH with present rib (i.e., T-rib or the concave T-rib) has been observed to be more than SAH with other shapes of ribs used by previous researchers.
... Some confuse the Constructal Law with an assumed natural evolutionary trend with toward "more flow," which is not correct. The natural tendency is to evolve freely into flow configurations that offer greater access to what flows, not more flow [20]. According to [21], in summary, the evolution of systems is strictly connected with the possibility of their morphing configuration, permitting that the new configurations replace existing configurations, to perform better (Constructal Law). ...
... The main outcomes of this approach clearly reveal that the others its extensions named new Bejan number [7] and general Bejan number [8] are new criteria of similarity obtained by combining the unique Bejan number (Be) with Prandtl number (Pr), for heat transfer process, or with Schmidt number for mass transfer process, respectively. This paper is an invitation to the next generations of researchers to review the field and its nomenclature and usefulness, as A. Bejan recommended in his latest 'trilogy', Bejan [10][11][12]. ...
Article
This paper presents new insight concerning the formulation and definition of one of the two Bejan numbers (Be) derived from the first and second law analysis, namely this one derived from the first law of thermodynamics. The systematic analysis performed reveals the role and physical meaning of the Bejan number (Be) as criterion of similarity or dimensionless variable. It is shown that the unique Bejan number (Be) can be derived from a classic fluid mechanics, whereas the other extensions of Bejan number (Be) for heat transfer or mass transfer are combinations of unique Bejan number (Be) with Prandtl (Pr) or Schmidt (Sc) numbers respectively.
... Ref. [1], p. 38). Both indicators, wealth and power, have grown spectacularly during the passed 200 years, hand in hand with the science of energy: thermodynamics, thermal design, and energy technology [3]. ...
... It states that a finite flow system with freedom to morph along time will evolve in such way to improve the access to the internal currents that flow through it [23][24][25][26]. In the context of engineering problems, several studies have been employed Constructal Theory aiming to improve the performance in design of cavities, fins, solid mechanics, heat exchangers and renewable energy [27][28][29][30][31][32][33][34]. Constructal Theory has already been used in thermal optimization applications of tube arrays. ...
Article
Present work performs a numerical study about the energy removal in a heated tubular array submitted to an external flow. Taking into account that a large variety of tubular arrangements can exists, in this work it is developed a tubular array that does not use any kind of initial predefined arrangement. Using the principles of Constructal Theory (or Law) and a positioning function dependent on the velocity and temperature fields, it is calculated, in a deterministic way, the location where each tube should be positioned. Pressure drop is not taken in to account in this first algorithm implementation as a performance indicator. In order to validate the proposed methodology, the Constructal Array is compared with standard aligned and staggered arrangements suggested in literature. The minimum distance between tubes (p) is considered as a degree of freedom. Four variations are studied: p = 1D, p = 1.25D, p = 1.5D and p = 2D, where D is the tube diameter. It is considered here the simulation of a transient, incompressible and laminar flow of a Newtonian fluid in a two-dimensional domain with forced convection and Prandtl number equal to 0.71. Results are computed when the flow reaches to the steady state condition. It is evaluated three values for Reynolds number: Re D = 10, 50 and 100. Thermal analysis of the formed patterns has shown that best thermal performance was not obtained with p = 1D, neither with p = 2D, i.e., tube distance has an influence on its formation and, consequently, on the heat transfer exchange. In all performed analyzes, Constructal arrays configuration showed higher energy removal (up to 71%) than the aligned and staggered arrangements, which highlights the capacity of proposed method. Constructal Array for p = 1.5D showed the most homogeneous distribution and proved to be the most effective in 4 of the six studied cases.
... We adopted the normalized spectral entropy here, which is an entropy measurement. Entropy is initially a physical quantity in thermodynamics that characterizes the degree of disorder in the state of molecules [30]. In 1948, information entropy was proposed by Shannon to solve the problem of quantifying information and clarifying the relationship between the probability of information occurrence and information redundancy [31]. ...
Article
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Permafrost is characterized by low temperature, and its thermal stability is key to geohydrological cycles, energy exchange, and climate regulation. Increasing engineering activities, i.e., road construction and operations, are affecting the thermal stability in permafrost regions and have already led to the degradation of permafrost and caused environmental problems. To understand the spatiotemporal influence of road construction and operations on the thermal dynamics in permafrost regions, we conducted a study in the Ela Mountain Pass where multiple roads intersect on the Qinghai–Tibet Plateau (QTP) and calculated the thermal dynamics from 2000 to 2017 using normalized spectral entropy (measuring the disorderliness of time-series data). Our results indicate that road level is a significant influencing factor, where high-level roads (expressways) exhibit stronger thermal impacts than low-level roads (province- and county-level roads). Our results also indicate that duration of operation is the most significant factor that determines the thermal impacts of roads on permafrost: the thermal impacts of the newly paved expressway are positively related to elevation, while the thermal impacts of the old expressway are positively related to less vegetated areas. The study provides an excellent method for understanding the spatiotemporal impacts of engineering activities on the temperature dynamics in permafrost regions, thereby helping policymakers in China and other countries to better plan their infrastructure projects to avoid environmentally vulnerable regions. The study also calls for advanced techniques in road maintenance, which can reduce the accumulated disturbance of road operations on permafrost regions.
... The constructal law shows that, besides the conventional "arrow" of time given by the second law of thermodynamics, there is another one for flow organization. This flow organization arrow has been presented since the birth of thermodynamics, but it was not recognized until recently, with the advent of the constructal law [10]. In macroscopic terms, this is the physics of the phenomenon of design, the natural tendency of flow systems to evolve into configurations that provide greater access over time [11]. ...
Article
This work relies on the constructal design method associated with exhaustive search and genetic algorithms to perform geometric optimization of an asymmetric tri-forked pathway of highly conductive materials (inserts) that remove a constant heat flux from a body and deliver it to three isothermal heat sinks. It is shown numerically that the global thermal resistance, represented by the maximum excess of temperature, can be minimized by means of geometric evaluation subject to two constraints, the total rectangular area where the forked pathway is circumscribed and the tri-forked pathway area, and seven degrees of freedom. A parametric study is performed to show the influence of the degrees of freedom over the global thermal resistance. The optimal geometry was obtained for a 40% area fraction, leading to a maximum excess temperature seven-times minimized with a thermal performance 627% better than a once optimized architecture, showing the importance of the design for thermal performance. For higher values of aspect ratio, height/length, the optimal configuration is highly asymmetrical, while for lower ratios the bifurcated branches has low influence over the thermal performance of the system. The optimal tri-forked pathway presented a 307% lower thermal global resistance compared to a V-shaped pathway on the same conditions.
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The tracheobronchial tree is commonly seen to have a systematic branching symmetry, despite being known to have an asymmetrical design. Branching asymmetry allows for uniform airflow and provides robustness against the morphogenesis-related size variability. Here, a constructal approach is used to tracheobronchial tree analysis, and a general model based on entropy generation during breathing process is provided, which holds with asymmetric characteristics of the tree, and the change for inhaling and exhaling air. In contrast to traditional models available in the literature, the entropy generation of inspiration and expiration processes is compared for symmetry and asymmetric designs. This approach unravels the fundamental consequences of asymmetric constraint in the process of breathing and provides justification for the tracheobronchial tree having the same number of bifurcation levels as optimized symmetrical trees.
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In this paper, the different forms of the Clausius statement of second law of thermodynamics presented by various authors have been critically reviewed and compared with the original statement of Clausius to identify the variations. The notable deviations from the original Clausius statement have been found regarding the conditions and constraints for applicability of this law, which can be of great concern for engineers. It has been found that the original statement has no ambiguity and it addresses all the issues relating to heat transfer between cold and hot bodies and hence it has been concluded that the original Clausius statement of the law must be always stated verbatim. Since the engineers regard two-way radiation heat transmission for net heat transfer calculation, i.e., from hot to the cold as well as from cold to the hot body, the law has been reviewed from a heat transfer engineer's point of view for the radiation heat transfer and modification in the original Clausius statement or inclusion of an explanation has been suggested for the sake of clarity or to avoid any ambiguity.
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Analytical simulation of spectral features for evolution of biosystem based on the model of system with infinite number of conserved random links with environment is conducted. Assumption of conservation presumes that the links are executed by appropriate continuity equation. Besides, it is believed that any exchange process between system and environment has an energy dimension. The solution for a total energy exchange quantity E, average efficiency of energy exchange ϒ and related entropy S is found. Solution E demonstrates the interlayer spectral structure when the continuous spectrum is interleaved with the quasi-discrete one. In turn, spectrum for entropy S comes in the bandpass quasi-continuous form. The pair nature of discrete points, relation between optimization and discreteness is also demonstrated. Taken altogether above features enable to think on existence of an obligatory energy infrastructure for evolving biosystem. This infrastructure is formed by combination of the spectral elements, such as nodes and internode segments.
Preprint
Evolution is fundamental to natural sciences and social sciences. Existing evolutionary theories are incomplete and unable to explain multiple evolutionary issues. To establish a comprehensive and comprehensible evolutionary theory, we employ the concept carbon-based entities (CBEs), which include methane, glucose, proteins, organisms, and other entities chemically containing carbon atoms. We deduce the steps, driving forces, and mechanisms of evolution of CBEs, through integration of geology, physics (particularly the second law of thermodynamics), chemistry (particularly chemical reactions of CBEs), and biology (particularly the essence of reproduction, genomes, and natural selection). We hence establish the Carbon-Based Evolutionary Theory (CBET), which suggests that evolution is the increase in the amount, diversity, and fitness of higher-hierarchy CBEs under natural selection and driven by the organic synthesis tendency on the Earth from the thermodynamic features of the Earth. It provides better explanations for various evolutionary issues (e.g. life origin, neutral mutation, speciation, and evolutionary tempos) than existing evolutionary theories. It reveals the physiochemical roots of biological evolution and the evolutionary roots of multiple social notions important to harmonious development of human society. It refutes from a novel respect some incorrect thermodynamic notions regarding evolution (e.g. negative entropy). It hence removes contradictions between physiochemistry, biology, and social sciences, and bridges them through evolution. The CBET is reliable as per its deduction and applications. Therefore, the CBET is more scientific and comprehensive than existing evolutionary theories, and could have great significance in natural sciences and social sciences. Meanwhile, the CBET is open to optimization and extension.
Preprint
To establish a comprehensive and comprehensible evolutionary theory, and to use this theory to bridge physics, biology, and social sciences, we employ the concept carbon-based entities (CBEs), which include methane, glucose, proteins, organisms, and other entities chemically containing carbon atoms. We deduce the steps, driving forces, and mechanisms of evolution of CBEs through integration of geology, physics, chemistry, and biology. We hence establish the Carbon-Based Evolutionary Theory (CBET), which suggests that evolution is the increase in the amount, diversity, and fitness of higher-hierarchy CBEs under natural selection and driven by the organic synthesis tendency on the Earth from the thermodynamic features of the Earth. It provides better explanations for various evolutionary issues and social issues (e.g. life origin, natural selection, neutral mutation, diversity importance, and altruism) than previous theories. It refutes some incorrect views (e.g. negative entropy) in thermodynamics on evolution. The CBET could have great significance in various sciences.
Article
Different designs of novel coolant (i.e., water) circuits have been proposed using a well-established constructal law to cool a square substrate made up of aluminum oxide, and subjected to a uniform wall heat flux. Five different flow-path topologies: Case-1 (umbrella-shaped), Case-2 (dumbbell-shaped), Case-3 (hexagonal-shaped), Case-4 (down-arrow-shaped), and Case-5 (up-arrow-shaped) are evolved from a single pipe embedded in the heated substrate. The best cooling pathway has been anticipated by comparing the thermo-fluid characteristics of designs. A numerical route, via Ansys R 16, has been implemented to solve the transport equations for continuity, momentum, and energy along with relevant boundary conditions. The non-dimensional temperature and pressure drop for these cases have been quantified and compared, by varying the length and Reynolds number in the range of 2-3, and 100-2,000, respectively. We observe a decrease in the dimensionless temperature and an increase in the pressure drop with Reynolds number for all the considered pathways. At Re<=500, a rapid fall in the non-dimensional temperature has been noticed; and thereafter, it looks like a plateau for all cases. For Case-4, a minimum temperature is obtained at the non-dimensional pipe length of 2.5. At Lc/L=2.5, we observe that the Case-4 provides better cooling to the substrate among all other designs. Also, the pressure drop for case 4 is not too high as compared to other designs.
Article
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The employment of heat exchangers with complex channels has increasing importance in several engineering problems as commercial refrigeration and cooling of electronic packages. One important subject in this kind of device is the design of corrugated channels. Therefore, the present work aims at the geometric optimization of trapezoidal blocks mounted in channels subjected to steady, incompressible, laminar, two-dimensional forced convective flows. The computational domain studied here mimics the corrugated channels commonly found in micro-channel heat exchangers. For the geometrical investigation, it is employed the Constructal Design Method. The numerical simulations were performed for two Reynolds numbers (ReH) equal to 60 and 160 and constant Prandtl number (Pr = 6.99). Results demonstrated that the length/height ratios of both studied blocks (given by L1/H1and L2/H2ratios) have the highest sensibility over the thermal performance, showing the importance of the channel's blocks intrusion. It was also shown that the combined analysis of the ratios L1/H1and L2/H2was much more efficient for the improvement of the heat transfer rate in the corrugated channels. The thermal performance increased by nearly 65% when the best and worst configurations were compared.
Article
This is a review of several key ideas and pioneers in the founding history of thermodynamics, fluid dynamics and heat transfer. Ideas treated in detail are the mechanical equivalent of heat, the difference between heat transfer and work transfer, the Navier-Stokes equations, natural convection in a fluid and a saturated porous medium, the gas bubble rising in a vertical tube filled with liquid, and fluid friction in duct flow. The review shows that good ideas spread and, at the same time the language and national preferences of the followers play a role in whether the idea creators are remembered or forgotten. The forgetting of the origin of ideas and their authors threatens to become a real problem during the digital era. This danger is exacerbated by the enormous increase in the number of publications most of which are not carefully reviewed or read.
Preprint
Studies on evolution have made significant progress in multiple disciplines, but evolutionary theories remain incomplete, controversial and inadequate in explaining origin of life and macroevolution. Here we create the concept of carbon-based entities (CBEs) which include methane, amino acids, proteins, bacteria, animals, plants, and other entities containing carbon atoms. From thermodynamics, we deduce the driving force, the progressive mechanisms, and the major steps of CBE evolution, and hence establish a comprehensive evolutionary theory termed the CBE evolutionary theory (CBEET). CBEET highlights that evolution is driven hierarchy-wise by thermodynamics and favors fitness and diversity. It provides novel explanations for origin of life (abiogenesis), macroevolution, natural selection, sympatric speciation, and animal group evolution in a comprehensive and comprehensible way. It elucidates that collaboration, altruism, obeying rules with properly increased freedom are important throughout the CBE evolution. It refutes thoroughly the notion that negative entropy (negentropy) leads to biological order which is distinct from thermodynamic order. It integrates with research advances in multiple disciplines and bridges laws of physics, evolution in biology, and harmonious development of human society.
Preprint
Studies on evolution have made significant progress in multiple disciplines, but evolutionary theories remain incomplete, controversial, and inadequate in explaining origin of life and macroevolution. Here we create the concept of carbon-based entities (CBEs) which include methane, amino acids, proteins, bacteria, animals, plants, and other entities containing carbon atoms. We then deduce the driving force, the progressive mechanisms, and the major steps of CBE evolution from thermodynamics. We hence establish a comprehensive evolutionary theory termed the CBE evolutionary theory (CBEET), which suggests that evolution is driven hierarchy-wise by thermodynamics and favors fitness and diversity. The CBEET provides novel explanations for origin of life (abiogenesis), macroevolution, natural selection, sympatric speciation, and animal group evolution in a comprehensive and comprehensible way. It elucidates that collaboration, altruism, obeying rules with properly increased freedom are important throughout the CBE evolution. It refutes thoroughly the notion that negative entropy (negentropy) leads to biological order which is distinct from thermodynamic order. It integrates with research advances in multiple disciplines and links up laws of physics, evolution in biology, and harmonious development of human society.
Article
The present computational study comprises the geometrical investigation using the Constructal Design of a triangular array of bluff bodies subjected to incompressible, transient, and forced convective flows in a two-dimensional domain. It is considered a Reynolds and Prandtl numbers of ReD = 100 and Pr = 0.71. The body areas and the maximum occupation area of the array are the problem constraints. The problem has three degrees of freedom (DOF): ST/D, SL/D (ratios between transverse and longitudinal pitch over characteristic dimension D, respectively), and H1/L1 (height and length ratio of the upstream body of the arrangement). The objectives are to minimize the drag coefficient (CD¯) and maximization of heat transfer rate per unit length (q¯′) of the arrangement. Conservation equations of mass, momentum, and energy are solved with the Finite Volume Method (FVM). Results indicated a significant gain in the fluid dynamic and thermal performances of 68.85% and 100.34%, respectively when the best and worst shapes are compared. Moreover, variations of the ratio H1/L1 strongly affected the behavior of CD¯ and q¯′ as a function of ST/D and SL/D and optimal designs. Thermal streams with complex vortex structures distributed in tree-shaped patterns led to the highest heat transfer rate magnitudes.
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The application of constructal networks to cool a heat‐generating volume has been the subject of many research studies in the past decade. However, the current volume‐point constructs mainly include rectangular, triangular, and parabolic‐shaped constructs, and none of them are similar to the constructs of common plant leaves in nature. A bionic quadrilateral volume based on the shape of common leaf veins is proposed, and the heat‐conductive model of the quadrilateral volume is established. The analysis results show that the minimal peak temperature difference can be as low as 1.3k when the porosity α1 of the quadrilateral volume is equal to 0.15; the recommended value of interval number n of central link is 30, the optimal value of exponent m1 of the width of central link is about 0.9; and the optimal value of the aspect ratio H1/L1 remains nearly constant at 0.7. When the quadrilateral volume obtains highest heat conductivity, the branching cooling links should be perpendicular to the central link.
Article
Heat transfer between two streams of hot and cold fluids separated by a plate is an unavoidable exergy destruction process as a whole, i.e. the exergy gain from the cold fluid cannot fully cover the exergy loss of the hot. However, it is noticed that the amount of exergy destruction can be minimized by introducing the work done by the external gravity force that the natural convection of the third fluid in a closed loop driven by the hot and cold fluids themselves can enhance their heat transfer. Based on this idea, a heat transfer enhancement unit of a closed rectangular loop was constructed, the two parallel legs of which were vertically penetrated through a horizontal plate with one half on the hot side and the remained half on the cold side. In order to clarify the mechanism of heat transfer enhancement for the natural circulation loop (NCL), a numerical simulation was performed for a comparison between the heat transfer rates of the NCL and the copper fin with the same shape and size. The effects of side length, velocities of heating and cooling air, and temperature difference on the heat transfer rate were investigated in detail. The results show that the heat transfer rate of the NCL can be larger than that of the copper fin while the temperature difference is over a critical value.
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A heat conduction model with an arrow-shaped high thermal conductivity channel (ASHTCC) in a square heat generation body (SHGB) is established in this paper. By taking the minimum maximum temperature difference (MMTD) as the optimization goal, constructal designs of the ASHTCC are conducted based on single, two, and three degrees of freedom optimizations under the condition of fixed ASHTCC material. The outcomes illustrate that the heat conduction performance (HCP) of the SHGB is better when the structure of the ASHTCC tends to be flat. Increasing the thermal conductivity ratio and area fraction of the ASHTCC material can improve the HCP of the SHGB. In the discussed numerical examples, the MMTD obtained by three degrees of freedom optimization are reduced by 8.42% and 4.40%, respectively, compared with those obtained by single and two degrees of freedom optimizations. Therefore, three degrees of freedom optimization can further improve the HCP of the SHGB. Compared the HCPs of the SHGBs with ASHTCC and the T-shaped one, the MMTD of the former is reduced by 13.0%. Thus, the structure of the ASHTCC is proven to be superior to that of the T-shaped one. The optimization results gained in this paper have reference values for the optimal structure designs for the heat dissipations of various electronic devices.
Article
In this paper, we investigate the design-evolution of an embedded pipe based on the constructal theory to obtain the best design that cools a square plate subjected to a constant heat flux boundary condition. The water, ionic liquids (ILs), nano-enhanced ionic liquids (NEILs, i.e., [C4mim][NTf2]+Al2O3 and [C4mpyrr][NTf2]+Al2O3) have been used as the coolants. Several designs (Case-1 to Case-11) have been tested to quantify the non-dimensional temperature of the heated substrate by implementing the finite volume method of Ansys Fluent. The three-dimensional continuity, momentum, and energy equations have been solved iteratively in the fluid region by incorporating SIMPLE algorithm with appropriate boundary conditions; while the conduction equation is solved in the solid region. Among all the considered designs, it has been found that the Case-3 provides a better cooling effect for the heated substrate. For all of the considered configurations/designs, it is also found that the non-dimensional temperature decreases with the length of the morphing pipe. The NEILs exhibit a better cooling effect of the substrate as compared to the ILs and water. The present numerical methodology is also validated with the previous literature.
Chapter
Complexity is a lot like freedom: everybody knows, but very few can tell what it is. Complex is often confused with complicated and random. Complexity, organization, and evolution in nature are most powerful and useful when pursued as a discipline, not as jargon. A discipline has precise terms, rules, principles, and usefulness. The chapter reviews the central concepts and words that underpin the physics of evolutionary design today: information, knowledge, evolution, change, arrow of time, pattern, organization, drawings, complexity, fractal dimension, object, icon, model, empiricism, theory, and disorder and second law. A sequence of drawings is an evolving design. Configurations, as physical means to facilitate the flow of knowledge, are subject to the natural tendency toward evolution over time. Science needs both: the many small and the few large, the diversity and the unifying view, the many descriptions and the extremely few predictions, and the abundant empiricism and the rare theory.
Chapter
Designs (images with meaning) are everywhere, around us and inside us. Best known are the tree shaped flow structures of the river basins, human lungs, lightning, vascular tissue, urban traffic, snowflakes, river deltas, global air traffic, and vegetation. Other images go unnoticed, such as the round cross sections of ducts, blood vessels, pulmonary airways, galleries of earthworms, and the “pipes” carved by rainwater in wet soil and the hill slopes of the smallest rivulets of the river basin. Technologies employ round ducts, and for a good reason: they offer greater access to what flows, greater than in the absence of round cross sections. Less known are the rhythms of nature, the designs that represent organization in time, not in space. In most places, the flows that sweep areas and volumes flow in two distinct ways. In the river basin, the water first flows as seepage in the hill slopes (by diffusion), and later as streams in river channels. The first way is slow and short distance, while the second is fast and long distance. All flow systems in nature are driven by power, or work done per unit time. Work entails movement, deformation, morphing, and change. Humans “live” because they are driven by power derived from food and fuel and engines. All flowing architectures evolve with freedom in a discernible time direction, toward progressively greater access and more effective ways to flow over time, like the rivers and the animals.
Chapter
The physics of freedom is the universal phenomenon of evolution, with its many familiar manifestations. This program arches back to science itself—science as an evolutionary and self-correcting add-on that empowers humans. Why is this important? First, on the world map, you see a hierarchical flow that carries all the human features and concerns that we have discussed. You see the same hierarchical movement as you review the history lessons that you were given: books, movies, names, places, and human events. Second, society moves more, produces more, and is longer lasting when it is endowed with freedom, free questioning, and self-correcting. This second flow architecture coincides with the hierarchical distribution of creators and transmitters of science, on the same world map. Third, freedom is a physical feature, like shape, dimension, weight, change (process), and power. The freedom property is a measurement of how many features are free to be changed in the flow system configuration. Measurable is also the physical effect of freedom on efficiency and performance. Fourth, the physics of freedom is important to science itself. If free, science evolves and improves. Science evolves because we all want to predict and design the future. The effect of science is measurable in watts. The allocation of more power to more individuals is knowledge, which represents the design changes that keep us alive and moving easier, farther, and lasting longer in time. In summary, there is one phenomenon (evolution) and one law of evolution, and the physical feature that underpins them is freedom.
Article
Nature-inspired chemical engineering (NICE) is promising many benefits in terms of energy consumption, resilience and efficiency etc. But it struggles to emerge as a leading discipline, chiefly because of the misconception that mimicking Nature is sufficient. It is not, since goals and constrained context are different. Hence, revealing context and understanding the mechanisms of nature-inspiration should be encouraged. In this contribution we revisit the classification of three published mechanisms underlying nature-inspired engineering, namely hierarchical transport network, force balancing and dynamic self-organization, by setting them in a broader framework supported by nonequilibrium thermodynamics, the constructal law and nonlinear control concepts. While the three mechanisms mapping is not complete, the NET and CL joint framework opens also new perspectives. This novel perspective goes over classical chemical engineering where equilibrium based assumptions or linear transport phenomena and control are the ruling mechanisms in process unit design and operation. At small-scale level, NICE processes should sometimes consider advanced thermodynamic concepts to account for fluctuations and boundary effects on local properties. At the process unit level, one should exploit out-of-equilibrium situations with thermodynamic coupling under various dynamical states, be it a stationary state or a self-organized state. Then, nonlinear phenomena, possibly provoked by operating larger driving force to achieve greater dissipative flows, might occur, controllable by using nonlinear control theory. At the plant level, the virtual factory approach relying on servitization and modular equipment proposes a framework for knowledge and information management that could lead to resilient and agile chemical plants, especially biorefineries.
Article
This paper illustrates the method of evolutionary design with freedom by considering the problem of determining the distribution of the thickness of a high-conductivity layer (heat spreader) installed on a conducting wall. Heating comes from a steady line source imposed at t = 0. Heat spreads in time-dependent fashion in two directions: longitudinally by conduction along the layer and the wall, and transversally by conduction through the wall and then by convection into the flow that cools the other side of the wall. The heat spreading has two regimes, which are dictated by the two diffusion time scales along the layer and across the wall. It is shown that the solution to the optimal heat spreader thickness problem is the parabolic profile, and it is the same in both regimes of time-dependent conduction.
Article
This article presents the results of flows in "T" shaped duct bifurcations. The problem is to find the resistance to flow in three-dimensional (3D) structures with different homothetic relationships between sizes (diameters and lengths) of parent and daughter ducts. The method used is the Constructal Design, which is based on the Constructal Theory. The minimization of the global resistance to flow, subjected to geometric constraints of volume and area occupied by the ducts, is the key to search for optimum configurations. The flows investigated were three-dimensional, laminar, incompressible, in steady state, with uniform and constant properties. The results obtained numerically were verified via comparison with analytical results available in the literature. In this work, ranges of length and ratio of diameterss from 0.5 to 1 and 0.1 to 1, respectively, were investigated, for Reynolds numbers equal to 10 ² and 10 ³ . The main results indicate that the T-shaped structure with impermeable walls, agree with Hess-Murray's law.
Article
The constructal law was postulated in 1996 as the law of physics that accounts for the phenomenon of time evolution of configuration in all flow systems that have the freedom to morph: animate and inanimate, human made and not human made, social and individual. The constructal‐law field has grown rapidly during the past two decades, particularly with applications to evolutionary design in technology, and with predictions of evolutionary design in biology, geophysics, and social organization. In this review, we highlight some of the current research trends in this field. The topics chosen are from the past 5 years from the activity in our own group, for example, energy storage, heat exchangers, porous media, and technology evolution. The review ends with future directions for research in this very active field.
Article
This note offers a clear view of heat transfer fundamentals in terms of ‘heat tubes’, which are macroscopic architectures for the flow of energy through complex energy systems. The note focuses on heat tubes with conduction and convection, although heat tubes with radiation through stacks of radiation shields have also been treated in the literature. It is shown how to shape a heat tube and how to cool it along its length so that its thermodynamic performance evolves. Several instances of confusion are clarified along the way.
Article
The thermo-hydraulic and entropy generation characteristics of a square substrate imposed to a uniform heat flux (q″ = 200 W/m ² ) have been numerically investigated in the laminar regime (99.6 ≤ Re ≤ 1998) using finite volume method of Ansys Fluent R16. Six new constructal designs triangular (Case-1), dumbbell (Case-2), diamond (Case-3), H-shaped (Case-4), two-lobbed (Case-5) and three-lobbed (Case-6)) are obtained when the embedded pipe is freely morphed to have a greater and greater access to the heated regions of the square plate. First, the convection effect is neglected and the temperature of the plate as a function of the length of the loop is quantified. Second, the convection is taken into consideration and the temperature of the plate for all such configurations is quantified. Also, the pressure drop and entropy generation for all the designs have been compared with each other to get the best design among them. It has been observed that the diamond shaped configuration provides better cooling to the plate when their lengths are in range of 2⩽L c /L⩽2.74. For longer loops, H-shaped and three-lobbed designs are found to be the better design than the other designs. The pressure drop and total entropy generation for case-3 is found to be the lowest among all designs.
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This article demonstrates a multidisciplinary approach that proposes to augment future caregiving by prolonged independence of older adults. The human–robot system allows the elderly to cooperate with small flying robots through an appropriate interface. ASPIRE provides a platform where high-level controllers can be designed to provide a layer of abstraction between the high-level task requests, the perceptual needs of the users, and the physical demands of the robotic platforms. With a robust framework that has the capability to account for human perception and comfort level, one can provide perceived safety for older adults, and further, add expressively that facilitates communication and interaction continuously throughout the stimulation. The proposed framework relies on an iterative process of low-level controllers design through experimental data collected from psychological trials. Future work includes the exploration of multiple carebots to cooperatively assist in caregiving tasks based on human-centered design approach.
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Thermophotovoltaic (TPV) systems can convert radiant energy into electrical power. Here we explore the design of the TPV system cavity, which houses the emitter and the photovoltaic (PV) cells. Mirrors are utilized in the cavity to modify the spatial and spectral distribution within. After discussing the basic concentric tubular design, two novel cavity configurations are put forward and parametrically studied. The investigated variables include the shape, number, and placement of the mirrors. The optimization objectives are the optimized efficiency and the extended range of application of the TPV system. Through numerical simulations, the relationship between the design parameters and the objectives are revealed. The results show that careful design of the cavity configuration can markedly enhance the performance of the TPV system.
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In a recent paper [1] Reis showed that both the principles of extremum of entropy production rate, which are often used in the study of complex systems, are corollaries of the Constructal Law. In fact, both follow from the maximization of overall system conductivities, under appropriate constraints. In this way, the maximum rate of entropy production (MEP) occurs when all the forces in the system are kept constant. On the other hand, the minimum rate of entropy production (mEP) occurs when all the currents that cross the system are kept constant. In this paper it is shown how the so-called principle of "minimum energy expenditure" which is often used as the basis for explaining many morphologic features in biologic systems, and also in inanimate systems, is also a corollary of Bejan's Constructal Law [2]. Following the general proof some cases namely, the scaling laws of human vascular systems and river basins are discussed as illustrations from the side of life, and inanimate systems, respectively.
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Background Cells are open complex thermodynamic systems. They can be also regarded as complex engines that execute a series of chemical reactions. Energy transformations, thermo-electro-chemical processes and transports phenomena can occur across the cells membranes. Moreover, cells can also actively modify their behaviours in relation to changes in their environment. Methods Different thermo-electro-biochemical behaviours occur between health and disease states. But, all the living systems waste heat, which is no more than the result of their internal irreversibility. This heat is dissipated into the environment. But, this wasted heat represent also a sort of information, which outflows from the cell toward its environment, completely accessible to any observer. Results The analysis of irreversibility related to this wasted heat can represent a new approach to study the behaviour of the cells themselves and to control their behaviours. So, this approach allows us to consider the living systems as black boxes and analyze only the inflows and outflows and their changes in relation to the modification of the environment. Therefore, information on the systems can be obtained by analyzing the changes in the cell heat wasted in relation to external perturbations. Conclusions The bioengineering thermodynamics bases are summarized and used to analyse possible controls of the calls behaviours based on the control of the ions fluxes across the cells membranes.
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Darwin’s theory of evolution with focus on the origin of new species was formulated in an era in which the principles of genetics, biochemistry, physiology, communication etc. were not an issue. Numerous revolutionary new insights have since been gained. 1. The ‘sender-receiver communicating compartment”, a classical but still valuable concept, is better suited than ‘the cell’ to serve the role of universal unit of structure and function, ‘the cell’ being the smallest such unit; 2. Not only genetic, but non-genetic mechanisms as well contribute to variability that can be passed onto the next generation; 3. Natural selection, the almost unanimously accepted universal driving force of evolution, is itself the result of preceding problem-solving activity enabled by the principles of communication; 4. A logically deduced, unambiguous definition of ‘Life’ has been published so that now the key question can shift from Darwin’s formulation towards “How does ‘Life’, with its many aspects, change in the course of time”? Communication activity represents the very heart of being alive, thus of ‘Life itself’. In digital-era wording, living entities are hardware-software double continua. This paper advances an easily teachable change in paradigm, namely that evolution concerns ever changing complexes of signalling pathways, chemical and other, that occasionally yield both new species and additional (at least 16) levels of communication. This approach complements the genetic basis of the New Synthesis with several as yet undervalued mechanisms from physiology and development. In particular, ‘the universal self-generated electrical dimension of cells’ and Lamarckism deserve an upgrade.
Book
From engineering fluid mechanics to power systems, information coding theory and other fields, entropy is key to maximizing performance in engineering systems. It serves a vital role in achieving the upper limits of efficiency of industrial processes and quality of manufactured products. Entropy based design (EBD) can shed new light on various flow processes, ranging from optimized flow configurations in an aircraft engine to highly ordered crystal structures in a turbine blade. Entropy Based Design of Fluid Engineering Systems provides an overview of EBD as an emerging technology with applications to aerospace, microfluidics, heat transfer, and other disciplines. The text extends past analytical methods of Entropy Generation Minimization to numerical simulations involving more complex configurations and experimental measurement techniques. The book begins with an extensive development of basic concepts, including the mathematical properties of entropy and exergy, as well as statistical and numerical formulations of the second law. It then goes on to describe topics related to incompressible flows and the Second Law in microfluidic systems. The authors develop computational and experimental methods for identifying problem regions within a system through the local rates of entropy production. With these techniques, designers can use EBD to focus on particular regions where design modifications can be made to improve system performance. Numerous case studies illustrate the concepts in each chapter, and cover an array of applications including supersonic flows, condensation and turbulence. A one-of-a-kind reference, Entropy Based Design of Fluid Engineering Systems outlines new advances showing how local irreversibilities can be detected in complex configurations so that engineering devices can be re-designed locally to improve overall performance.
Book
Beginning with a short intellectual history of the academic culture wars, Eric Adler’s book examines popular polemics including those by Allan Bloom and Dinesh D’Souza, and considers the oddly marginal role of classical studies in these conflicts. In presenting a brief history of classics in American education, the volume sheds light on the position of the humanities in general. The book dissects three significant controversies from the era: the so-called AJP affair, which supposedly pitted a conservative journal editor against his feminist detractors; the brouhaha surrounding Martin Bernal’s contentious Black Athena project; and the dustup associated with Victor Davis Hanson and John Heath’s fire-breathing jeremiad, Who Killed Homer? The book concludes by considering these controversies as a means to end the crisis for classical studies in American education. How can the study of antiquity-and the humanities-thrive in the contemporary academy? Classics, the Culture Wars, and Beyond, provides workable solutions to end the crisis for classics and for the humanities as well. This major work also includes findings from a web survey of American classical scholars, offering the first broadly representative impression of what they think about their discipline and its prospects for the future. Eric Adler also conducted numerous in-depth interviews with participants in the controversies discussed, allowing readers to gain the most reliable information possible about these controversies. Those concerned about the liberal arts and the best way to educate young Americans should read this book. Accessible and jargon-free, this narrative of scholarly scandals and their context makes for both enjoyable and thought-provoking reading.
Book
Constructal Theory of Social Dynamics brings together for the first time social scientists and engineers to develop a predictive theory of social organization, as a conglomerate of mating flows that morph in time to flow more easily (people, goods, money, energy, information). These flows have objectives (e.g., minimization of effort, travel time, cost), and the objectives clash with global constraints (space, time, resources). The result is organization (flow architecture) derived from one principle of configuration evolution in time (the constructal law): "for a flow system to persist in time, its configuration must morph such that it provides easier access to its streams." Constructal theory predicts animal design and geophysical flows, and makes evolution a part of physics. In the social sciences, there is substantial literature based on the use of optima to deduce social, population and economic dynamics. The constructal approach of this book links social sciences with physics, biology and engineering. The book explores the deterministic principle that generates a broad array of patterned phenomena, in demography, geography, communications, hierarchy, and multiple scales. Examples are the distribution of living settlements, the occurrence of flow structure inside each settlement, ‘development’ as the relation between fast-flowing societies and advancement and wealth, migration patterns, and globalization. Constructal Theory of Social Dynamics is novel and important because it puts the occurrence of social organization on a scientific basis. It brings social organization under the same physics principle that accounts for the generation of flow architecture (design) in geophysical flows, animal design, and engineered flows. This exploratory work adds a dose of determinism to the modeling and predicting of societal flows.
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Cited By :1884, Export Date: 2 September 2017
Article
The purpose of this discussion is to increase the awareness of the divergent views on the entransy concept among the readers of chemical physics. Comments are presented in particular on the paper by Ahmadi et al. (2016) where the authors used entransy dissipation in their analysis. Based on the view points of independent different groups of researchers world wide, I draw the attention of readers to the reality that entransy has no physical meaning.
Article
Inequality " is a common observation about us, as members of society. In this article, we unify physics with economics by showing that the distribution of wealth is related proportionally to the movement of all the streams of a live society. The hierarchical distribution of wealth on the earth happens naturally. Hierarchy is unavoidable, with staying power, and difficult to efface. We illustrate this with two architectures, river basins and the movement of freight. The physical flow architecture that emerges is hierarchical on the surface of the earth and in everything that flows inside the live human bodies, the movement of humans and their belongings, and the engines that drive the movement. The nonuniform distribution of wealth becomes more accentuated as the economy becomes more developed, i.e., as its flow architecture becomes more complex for the purpose of covering smaller and smaller interstices of the overall (fixed) territory. It takes a relatively modest complexity for the nonuniformity in the distribution of wealth to be evident. This theory also predicts the Lorenz-type distribution of income inequality, which was adopted empirically for a century. Published by AIP Publishing. [http://dx.
Article
Why is size so important? Why are " economies of scale " a universal feature of all flow systems, animate, inanimate, and human made? The empirical evidence is clear: the bigger are more efficient carriers (per unit) than the smaller. This natural tendency is observed across the board, from animal design to technology, logistics, and economics. In this paper, we rely on physics (thermodynamics) to determine the relation between the efficiency and size. Here, the objective is to predict a natural phenomenon, which is universal. It is not to model a particular type of device. The objective is to demonstrate based on physics that the efficiencies of diverse power plants should increase with size. The analysis is performed in two ways. First is the tradeoff between the " external " irreversibilities due to the temperature differences that exist above and below the temperature range occupied by the circuit executed by the working fluid. Second is the allocation of the fluid flow irreversibility between the hot and cold portions of the fluid flow circuit. The implications of this report in economics and design science (scaling up, scaling down) and the necessity of multi-scale design with hierarchy are discussed. Published by AIP Publishing.
Chapter
Not all processes allowed by the first law of thermodynamics actually occur; there are limitations that are expressed in a number of generalisations of experience that are known as the second law of thermodynamics. The simplest statement of the second law is that when two closed systems interact thermally, the hotter system always becomes cooler and the cooler system always becomes hotter. In terms of the heat flow that occurs, this statement may be put in the form: when two closed systems are placed in thermal contact, the direction of the energy transfer as heat is always from the system at the higher temperature to that at the lower temperature. This is the Clausius statement of the second law.
Article
The purpose of this discussion is to increase the awareness of the divergent views on the entransy concept among the readers of chemical physics. Comments are presented in particular on the paper by Ahmadi et al. [1] where the authors used entransy dissipation in their analysis. Based on the view points of independent different groups of researchers world wide, I draw the attention of readers to the reality that entransy has no physical meaning.
Article
Humans and technology are not in symbiosis. They are one species, not two. Humans, enveloped in artefacts of many kinds and ages (from writing, to airplanes), are evolving as one species, the ‘human & machine species’. This evolution is visible and recorded in our lifetime. Here, I illustrate the evolution of the human & machine species by focusing on commercial aircraft, the cooling of electronics, and modern athletics, which is a special laboratory for witnessing the evolution of animal locomotion. I show that these evolutionary forms of flow organization are in accord with, and can be predicted based on the law of physics that governs evolution in nature, bio and non-bio: the constructal law. Evolution, life and the human & machine species are physics.
Article
Until late in the 18th century, thermodynamics was seen as science of energy-Science of heat and work. During the eighteen century- or until late in the 18th century, heat was seen as a weightless fluid called "caloric". Heat will flow from high temperature to a low temperature producing useful work output conserving heat. 18th century engineers knew that machinery can be designed, and this heat flow can be used to produce useful work HEAT ENGINE. In this study, it will be shown how science of thermodynamics evolved within almost a century, as the science of energy, absolute temperature and entropy. It is also shown that how the availability (Exergy) is introduced as the second law analysis at the school of thermodynamics at MIT and now it can be used in Constructal thermodynamics as workable, efficient,solutions in analyzing energy systems and all components of all energy systems while protecting the environment.
Book
The book describes in a simple and practical way what non-equilibrium thermodynamics is and how it can add to engineering fields. It explains how to describe proper equations of transport, more precise than used so far, and how to use them to understand the waste of energy resources in central unit processes in the industry. It introduces the entropy balance as an additional equation to use, to create consistent thermodynamic models, and a systematic method for minimizing energy losses that are connected with transport of heat, mass, charge, momentum and chemical reactions. © 2010 by World Scientific Publishing Co. Pte. Ltd. All rights reserved.
Article
Constructal theory, now called constructal law, has influenced and driven a significant amount of research and attention over the past 2 decades due to its significance in understanding designs found in nature. It is worth to remember that the origins of constructal law can be traced back to the design of heat conduction paths, alternatively called access problem, in Bejan’s 1996 paper. However, it is evident that although branching designs are generated, geometric and ‘constructal’ constraints are always present and often not relaxed in their designs. In this paper, additional design explorations to solutions for the access problem are sought and discussed. Density based topology optimization under 6 different, tunable material interpolation models are chosen since design explorations can be considered to be straightforward for finding solutions and the design process is relaxed. The variation in the material property model highlights the importance of search spaces in any design process. To give fair comparisons, the final designs obtained from the optimization process are projected as 0–1 designs. The results reveal other topologies that perform better as compared to two constructal design cases. The significant difference starting from the fundamentals of constructal designs is also discussed.
Article
An advanced, practical approach to the first and second laws of thermodynamics. Advanced Engineering Thermodynamics bridges the gap between engineering applications and the first and second laws of thermodynamics. Going beyond the basic coverage offered by most textbooks, this authoritative treatment delves into the advanced topics of energy and work as they relate to various engineering fields. This practical approach describes real-world applications of thermodynamics concepts, including solar energy, refrigeration, air conditioning, thermofluid design, chemical design, constructal design, and more. This new fourth edition has been updated and expanded to include current developments in energy storage, distributed energy systems, entropy minimization, and industrial applications, linking new technologies in sustainability to fundamental thermodynamics concepts. Worked problems have been added to help students follow the thought processes behind various applications, and additional homework problems give them the opportunity to gauge their knowledge. The growing demand for sustainability and energy efficiency has shined a spotlight on the real-world applications of thermodynamics. This book helps future engineers make the fundamental connections, and develop a clear understanding of this complex subject. Delve deeper into the engineering applications of thermodynamics. Work problems directly applicable to engineering fields. Integrate thermodynamics concepts into sustainability design and policy. Understand the thermodynamics of emerging energy technologies. Condensed introductory chapters allow students to quickly review the fundamentals before diving right into practical applications. Designed expressly for engineering students, this book offers a clear, targeted treatment of thermodynamics topics with detailed discussion and authoritative guidance toward even the most complex concepts. Advanced Engineering Thermodynamics is the definitive modern treatment of energy and work for today's newest engineers.
Article
A classification representing some main branches of phenomenological non-equilibrium thermodynamics is discussed. Differences and similarities of these selected branches are explained. Starting out with basic concepts of phenomenological thermodynamics, more developed theories with different back-grounds contributing to contemporary thermodynamics are considered. Because of its vast extent, this field cannot be presented completely in a single reasonably sized paper without any omissions.
Article
Here, we show that during their half-century history, helicopters have been evolving into geometrically similar architectures with surprisingly sharp correlations between dimensions, performance, and body size. For example, proportionalities emerge between body size, engine size, and the fuel load. Furthermore, the engine efficiency increases with the engine size, and the propeller radius is roughly the same as the length scale of the whole body. These trends are in accord with the constructal law, which accounts for the engine efficiency trend and the proportionality between “motor” size and body size in animals and vehicles. These body-size effects are qualitatively the same as those uncovered earlier for the evolution of aircraft. The present study adds to this theoretical body of research the evolutionary design of all technologies [A. Bejan, The Physics of Life: The Evolution of Everything (St. Martin's Press, New York, 2016)].
Article
Here we show that bodies of the same size suspended uniformly in space constitute a system (a “suspension”) in a state of uniform volumetric tension because of mass-to-mass forces of attraction. The system “snaps” hierarchically, and evolves faster to a state of reduced tension when the bodies coalesce spontaneously nonuniformly, i.e., hierarchically, into few large and many small bodies suspended in the same space. Hierarchy, not uniformity, is the design that emerges, and it is in accord with the constructal law. The implications of this principle of physics in natural organization and evolution are discussed.
Article
Physics is concise, simple, unambiguous, and constantly improving. Yet, confusion reigns in the field especially with respect to complexity and the second law of thermodynamics. In this paper, we step back and take a look at these notions—their meaning and definition—on the background provided by nature and thermodynamics. We review the central concepts and words that underpin the physics of evolutionary design today: information, knowledge, evolution, change, arrow of time, pattern, organization, drawings, complexity, fractal dimension, object, icon, model, empiricism, theory, disorder, second law, the “any” system in thermodynamics, morphing freely, and the constructal law. We show, for example, that information is not knowledge, fractal dimension is not a measure of complexity, and pattern is not a live flow architecture. Drawings, as physical means to facilitate the flow of knowledge, are subject to the natural tendency toward design evolution. Complexity, organization, and evolution in nature are most powerful and useful when pursued as a discipline, with precise terms, rules, and principles.
Article
Here we report the discovery that even the simplest, oldest and most prevalent forms of evolutionary movement—rolling bodies and whirls of turbulence—exhibit the same body-size effect on life time and life travel as the evolutionary movement united by the body-size effect so far: animals, rivers, vehicles, jets and plumes. In short, the bigger should last longer and travel farther. For rolling bodies, the life span (t) and the life travel (L) should increase with the body mass (M) raised to the powers 1/6 and 1/3, respectively. The number of rolls during this movement is constant, independent of body size. For an eddy of turbulence, t should increase with the eddy mass (M) raised to the power 2/3, while L should increase with M2/3 times the bulk speed of the turbulent stream that carries the eddy. The number of rolls during the eddy life span is a constant independent of eddy size.
Article
Cells are open complex thermodynamic systems. Energy transformations, thermo-electro-chemical processes and transports occur across the cells membranes. Different thermo-electro-biochemical behaviours occur between health and disease states. Moreover, living systems waste heat, the result of the internal irreversibility. This heat is dissipated into the environment. But, this wasted heat represent a sort of information, which outflows from the cell toward its environment, completely accessible to any observer. Consequently, the analysis of irreversibility related to this wasted heat can represents a new approach to study the behaviour of the cells. So, this approach allows us to consider the living systems as black boxes and analyze only the inflows and outflows and their changes in relation to the modification of the environment. Therefore, information on the systems can be obtained by analyzing the changes in the cell heat wasted in relation to external perturbations. In this paper, a review of the recent results obtained by using this approach is proposed in order to highlight its thermodynamic fundamental: it could be the beginning of a new engineering science, the bioengineering thermodynamics. Some experimental evidences from literature are summarized and discussed. The approach proposed can allow us to explain them.
Article
People like to say that energy and water are two problems, two vital commodities in short supply. Here I draw attention to the emerging literature and physics principle (constructal law) that provide the scientific foundation for sustainability. I show that the sustainability need is about flow : the flow of energy and the flow of water through the inhabited space. All the flows needed for human life (transportation, heating, cooling, water) are driven by the purposeful consumption of fuels. This is why the wealth of a country (the GDP) is directly proportional to the annual consumption of fuel in that country. This hierarchical organization happens; it is natural and efficient. Sustainability is the one-word need that covers all the specific needs. Sustainability comes from greater freedom in changing the organization – the flow architecture – that sustains life. Greater freedom to change the design (from water and power to laws and government) leads to greater flow, wealth, life and staying power, i.e. sustainability.
Article
Here, we report the numerical study of time dependent storage of energy by melting a phase change material. The heating is provided along invading lines, which change from single-line invasion to tree-shaped invasion. The numerical simulations show that the history of the amount of melted material is S-shaped. We also found that the fastest melting (i.e., the steepest S curve) is discovered by allowing the tree architecture to morph freely, toward greater access over time. The stem length and branching angle of invading trees can be selected such that the complete melting process is shorter. The melting process can also be made faster by increasing the complexity of the tree structure.
Article
Biological evolution represents one of the most successful, but also controversial, scientific concepts. Ever since Charles Darwin formulated his version of evolution via natural selection, biological sciences experienced explosive development and progress. First of all, although Darwin could not explain how traits of organisms, selected via natural selection, are inherited and passed down along generations; his theory stimulated research in this respect and resulted in the establishment of genetics and, still later, with the discovery of DNA and genome some hundred years after his evolutionary theory. Nevertheless, there are also several weaknesses in classical Darwinian as well as the Neodarwinian gene-centric view of the biological evolution. The most serious drawback is its narrow focus: the modern evolutionary synthesis, as formulated in the 20th century, is based on the concept of gene and on mathematical/statistical analysis of populations. While the Neodarwinism is still generally valid theory of biological evolution, its narrow focus and incompatibility with several new findings and discoveries calls for its update and/or transformation. Either it will be replaced with an updated version or, if not flexible enough, it will be replaced by a new theory. In his book ‘Evolution - A New View from the 21st Century’, James A. Shapiro has discussed these problems as well as newly emerging aspects which are changing our understanding of biological evolution. This new book joins a row of several other recent books highlighting the same issues.
Article
The book contains research results obtained by applying Bejan's Constructal Theory to the study and therefore the optimization of fins, focusing on T-shaped and Y-shaped ones. Heat transfer from finned surfaces is an example of combined heat transfer natural or forced convection on the external parts of the fin, and conducting along the fin. Fin's heat exchange is rather complex, because of variation of both temperature along the fin and convective heat transfer coefficient. Furthermore possible presence of more fins invested by the same fluid flow has to be considered. Classical fin theory tried to reduce the coupled heat transfer problem to a one-dimensional problem by defining an average temperature of the fin and writing equations using this parameter. However, it was shown that this approach cannot be used because of the effects of two-dimensional heat transfer, especially in the presence of short fins. CFD codes offer the possibility to consider bi-dimensional (and more generally, three-dimensional) effects and then a more real approach to the physic phenomena of finned surface's heat exchange. A commercial CFD code was used to analyse the case of heat exchange in presence of T-shaped fins, following an approach suggested by Bejan's Constructal Theory. The comparative results showed a significant agreement with previous research taken as a reference, and this result allows for the application of this approach to a wider range of systems. T-shaped optimized fin geometry is the starting point for further research. Starting from the optimal results (T-shape optimized fins), we show the trend of the assessment parameter (the dimensionless conductance) in function of the angle α between the two horizontal arms of the fin. It has not been found a value for α, 90° < α < 180°, capable of a higher value of the dimensionless conductance, has not been found. The thermal efficiency showed a significant increase of this parameter, especially for values of α smaller than 100°. Thus, a new definition of optimisation is achieved by introducing the fundamental "space factor." The present work unifies the "classic" definitions of optimisation and efficiency in a new general performance criterion, opening a new perspective on multi-fin systems. The last chapter deals with a brief overview on Bejan's Constructal Theory. It explains either tree-shape natural flows or other geometric form in nature and engineering, applying the principle of performance maximization. The Constructal principle also recognizes that a new good form comes to another previous good form which serve the same objective and have the same constraints. Changes in configuration are dynamic, thus a time arrow is then associated to the evolution in system's configuration.