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An active fluidization thermal energy storage (TES) called “sandTES” is presented. System design, the fundamental features and challenges of fluidization stability such as mass flux uniformity, powder transport and heat transfer, as well as auxiliary power minimization are thoroughly discussed. The tools and methods for evaluating or simulating the...
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... This process reduces the air temperature. To improve the system's efficiency, the exiting air, which remains at a relatively high temperature, will be recovered and used both to fluidize and preheat the particles [56]. This heat exchange system is similar to the one used in [57]. ...
Spain’s energy transition poses the dual challenge of managing renewable curtailment and enhancing the competitiveness of concentrated solar power (CSP) technologies. This study evaluates the suitability of replacing molten salts with solid particles for energy storage and, additionally, explores the storage of surplus electricity from grid in Carnot batteries. Four scenarios were analyzed using a Gemasolar-type plant model: each storage medium was studied with and without the integration of curtailed electricity. The solar field was modeled with SAM (System Advisor Model), while curtailment data from Red Eléctrica de España (2016–2021) quantified the available surplus. Results show that solid particles lead to 7.4% higher annual electricity production compared to molten salts, mainly due to improved power cycle efficiency. The integration of curtailment increased output further, with the solid particle Carnot battery scenario achieving the highest performance (up to 19.0% sun-to-electricity efficiency and 69.7% capacity factor). However, round-trip efficiency for curtailment storage was limited (~25–27%), and although solid particles showed lower LCOE (levelized cost of energy) than salts (192 vs. 211 USD/MWh), the Carnot battery increased costs. These findings suggest that while solid particles offer clear advantages, the economic viability of Carnot batteries remains constrained by current cost and operational limitations.
... Heat transfer coefficient of a fluidized bed (silica sand)[31]. ...
With the growing demand for plastic production and the importance of plastic recycling, new approaches to plastic waste management are required. Most of the plastic waste is not biodegradable and requires remodeling treatment methods. Chemical recycling has great potential as a method of waste treatment. Plastic pyrolysis allows for the cracking of plastic polymers into monomers with heat in the absence of oxygen, allowing energy recovery from the waste. Fluidized bed reactors are commonly used in plastic pyrolysis; they have excellent heat and mass transfer. This study investigates the influence of low and medium process temperatures of pyrolysis on fluidized bed reactor parameters such as static pressure, fluidizing gas velocity, solid movement, and bubble formation. This set of parameters was analyzed using experimental methods and statistical analysis methods such as experimental correlations of changes in fluidized bed reactor velocities (minimal, terminal) due to temperature increases for different particle sizes; CFD software simulation of temperature impact was not found. In this study, computational fluid dynamics (CFD) analysis with Ansys Fluent was conducted for the fluidization regime with heat impact analysis in a fluidized bed reactor (FBR). FBR has excellent heat and mass transfer and can be used with a catalyst with low operating costs. A two-phase Eulerian–Eulerian model with transient analysis was conducted for a no-energy equation and at 100 °C, 500 °C, and 700 °C operating conditions. Fluidizing gas velocity increases the magnitude with an increase of the operating temperature. The point of fluidization could be determined at 1.1–1.2 s flow time at the maximum pressure drop point. With the increase of gas velocity (to 0.5 m/s from 0.25 m/s), fluidizing bed height expands but when the solid diameter is increased from 1.5 mm to 3 mm, the length of the fluidized region decreases. No pressure drop change was observed as the fluidized bed regime was maintained during all analyses. The fluidization regime depends on gas velocity and all the applied fluidization gas velocities were of a value in between the minimal fluidization velocity and the terminal velocity.
... Die SandTES-Technologie ist ein thermisches Energiespeichersystem (TES), welche am Institut für Energietechnik und Thermodynamik (IET) der TU Wien entwickelt wurde. Diese basiert auf einer Kombination einer Wirbelschichttechnologie und eines Gegenstromwärmeübertragers (Schwaiger 2014 In Abb. 12.5 können die Parameter des an der Dampfturbine anliegenden Dampfmassenstroms abgelesen werden. ...
Das vorliegende Buch brachte erste Einblicke in das spannende Berufsfeld von WirtschaftsingenieurInnen und zeigte gleichzeitig die Kompetenzvielfalt auf, welche für die Ausübung des Berufs notwendig ist. In diesem abschließenden Kapitel bieten die HerausgeberInnen dieses Buches den „JungautorInnen“ die Möglichkeit sich zu präsentieren und fokussieren zusammenfassend die Ausbildung von künftigen WirtschaftsingenieurInnen und die Möglichkeit zur Vernetzung innerhalb der Community.
... FBs have been employed for solar energy applications, considering configurations operating in bubbling, spouted, circulating regimes (see Table 1, Types A-C "ordinary" configurations), and special and novel designs (Types D-J). Early studies successfully pioneered the application of ordinary FBs operated in the bubbling (Flamant, 1982;Bachovchin et al., 1983) and circulating (Koenigsdorff and Kienzle, 1991;Werther et al., 1994) inherent mobility of fluidized particles received further confirmation in subsequent studies (Flamant et al., 1988;Glicksman et al., 1988;Chirone et al., 2013;Pardo et al., 2014;Schwaiger et al., 2014;Salatino et al., 2016;Tregambi et al., 2016;Milanese et al., 2017a;Tregambi et al., 2018a;Briongos et al., 2018;Miller et al., 2018;Bellan et al., 2019a;Tregambi et al., 2019a;Almendros-Ibáñez et al., 2019;Zhang and Wang, 2019;Sulzgruber et al., 2020a;Díaz-Heras et al., 2020b;Sulzgruber et al., 2020b;Park et al., 2020;Wünsch et al., 2020). Moreover, FBs, if properly designed and operated, may provide an appropriate environment for solar-driven heterogeneous chemical processes. ...
Thermal and thermochemical processes can be efficiently developed and carried out in fluidized beds, due to the unique properties of fluidized suspensions of solid particles and to the inherent flexibility of fluidized bed design and operation. Coupling fluidization with concentrated solar power is a stimulating cross-disciplinary field of investigation, with the related issues and opportunities to explore. In this review article the current and perspective applications of fluidized beds to collection, storage and exploitation of solar radiation are surveyed. Novel and “creative” designs of fluidized bed solar receivers/reactors are reported and critically discussed. The vast field of applications of solar-driven fluidized bed processes, from energy conversion with thermal energy storage, to solids looping for thermochemical energy storage, production of fuels, chemicals and materials, is explored with an eye at past and current developments and an outlook of future perspectives.
... The concept is a further development of the SandTES project [3], another TES system designed by the TU Wien IET. Contextual knowledge on this project can be found in [4][5][6]. ...
... One of the great advantages of countercurrent flow is the possibility of extracting a higher proportion of the heat content of the heating fluid compared to cocurrent flow. A possible tube bundle geometry for the FP-TES is presented in [21] or in [5] for a longer HEX. In case of electrical energy input, the HEX additionally contains electrical heating rods. ...
Due to the increasing amount of volatile energy in Europe's electricity system, the existing storage technologies and capacities are pushed to their limits. Therefore, new concepts like the sensible Fluidization Based Particle Thermal Energy Storage (FP-TES) can be a viable option. The FP-TES is working with bulk material as storage medium, which provides proven benefits like cost efficiency and low thermal losses. Moreover, the greatest advantage of the FP-TES compared to other particle based storage systems is the substitution of mechanical transport devices by an advanced fluidization technology. To prove and further develop this concept of particle transport, numerical simulations are performed. Consequently, an optimized geometry for a cold test rig, working with 800 kg quartz sand, is developed and its behaviour as well as particle mass flow and pressure drops are predicted. Furthermore, the results of experimental investigations performed with the test rig are compared to the numerical simulations. Both the simulation and the experiment show that controlled stable particle mass flow can be achieved by the developed advanced fluidization technology. Finally, a basic layout of an exemplary application is designed and the energetic efficiency is estimated.
... An example of underdeveloped functional unit is the particle conveyance system; even that the energy employed in moving the solid particles through the power plant can seriously affect the energy balance of the plant, and therefore its viability. There is only one reported solar tower developing some integration studies (the National Thermal Test Facility in New Mexico 19,20 ); nevertheless, reported studies show that their focus is centered in the receiver concept and HEX design. A full integration study can detect possible conflicts with the working requirements so that they can be properly solved. ...
... The most studied is the fluidized bed, which uses two-phase gas-solid HTF flow. 12,14,20 The solid phase corresponds to the particle media while the gas phase corresponds to pressurized air. This design has also been studied for latent and thermochemical storage heat discharge, besides the sensible heat used in particle media. ...
... 35,60 Also, silica sand can be easily presented in a large variety of size distribution and, since it is used for fluidization technology, the correlations used in fluidization engineering are valid. 20 Thereby, Diago et al 61 suggested silica sand as storage medium although the calcium content of the sand must be controlled since the highest the calcium content, the highest the sand agglomeration in the receiver. An alternate option to overcome agglomeration is to use two type of sand, a commercial silica and a foundry sand made from olivine. ...
Current concentrated solar power (CSP) plants that operate at the highest temperature use molten salts as both heat transfer fluid (HTF) and thermal energy storage (TES) medium. Molten salts can reach up to 565°C before becoming chemically unstable and highly corrosive. This is one of the higher weaknesses of the technology. Solid particles have been proposed to overcome current working temperature limits, since the particle media can be stable for temperatures close to 1000°C. This work presents a review of solid particles candidates to be used as HTF and TES in CSP plants in open receivers. In addition, the interactions between solid particles with major system components are described in this review, for example, with TES system or heat exchanger. The parameters and properties of solid particles are identified from the material science point of view explaining their nature and the relation to the power plant efficiency and lifetime durability. Finally, future development is proposed; such as material selection according to each specific design, materials characterization, or durability test.
... One of the key features about using particles for CSP applications is related to the TES system as no temperature constraints appear and its ease for handling and transportation. Due to those reasons, several researchers are proposing the use of particles-based TES systems for CSP plants [8][9][10][11] . The novelty of this work compared to previous research in this field is based on the detailed design proposal and thermal characterization of fluidized-bed heat exchangers (DPS-HX) connecting particles-based TES storage to subcritical and supercritical water-steam Rankine cycles for both small and large sizes. ...
In this paper, particles-based thermal energy storage (TES) system for concentrated solar power (CSP) is presented and applied to different CSP plant-layout scenarios. The key-component of this system is the fluidized-bed heat exchanger (DPS-HX) that is used for coupling particles-based storage system to the solar loop and to the power block. Mathematical model is used for the design and thermal performance analysis of the heat exchanger coupled to subcritical and supercritical Rankine steam cycles for small and commercial plant sizes. Among the benefits of particles-based thermal energy storage it can be pointed out no temperature restrictions with no freezing nor temperature degradation, ease of handling and no toxicity. It has been found that particles heat exchanger operates at high efficiency (from 91% to 99% for most of cases) and that power consumption for fluidization purposes are negligible compared to thermal power transferred to the work transfer fluid. For large power plant size, it is preferred distributing particles among different heat exchangers connected in parallel instead of passing whole particles and work transfer fluid through just one heat exchanger component.
... FBR designs with a strong focus on heat transfer between the bed and heat exchangers have previously been developed for other applications. Closest related to the design presented here are applications for indirect thermal storage using sand (Steiner et al., 2016Schwaiger et al., 2014Haider et al., 2012 ; ; ...
The reversible exothermic reaction of CaO with water is considered one of the most promising reactions for high temperature thermal energy storage. In this paper, a novel technical design of a MW-scale thermochemical energy storage reactor for this reaction is presented. The aim is to provide an easy, modular and scalable reactor, suitable for industrial scale application. The reactor concept features a bubbling fluidized bed with a continuous, guided solid flow and immersed heat exchanger tubes. To investigate the reactor design, a model is build using clustered CSTRs. The technical feasibility of the concept is proven in experimental tests, which are also used to identify key parameters of the model. Fluidization of the fine CaO/Ca(OH)2 powder was found to be challenging, but problems were overcome using mild calcination conditions and a special gas distributor plate. Using the model, it is found, that a thermal power of 15 MW can be expected from a reactor volume of 100 m3. To study influences of different parameters on the reactor model performance, a sensitivity analysis is carried out and heat transfer between the reactor and the immersed heat exchangers is found to have by far the largest influence and the reaction system performance. Future research should therefore focus more on heat transfer. Keywords: Thermal energy storage, CaO/Ca(OH)2, Fluidized bed, Large scale
... A large-scale prototype may be built under a beam-down solar concentrator (e.g., [62]). Several designs of solid particle heat exchangers have already been developed under the scope of similar projects (e.g., [63][64][65][66]), and can be coupled to the SandStock system during the experimental phase. ...
Desert dune sand is considered as a potential sensible heat thermal energy storage (TES) material. Several samples are collected from different locations of the desert in the United Arab Emirates (UAE), and relevant thermophysical and mechanical properties are measured. In addition, the optical properties of desert sand are investigated to evaluate its performance as a direct solar absorber. Thermogravimetric analyses show that the samples appear to be thermally stable between approximately 650 °C to 1000 °C following an initial mass loss occurring during the first heating cycle. The transformation of calcium carbonate into calcium oxide at higher temperature during the first heating process has a negative impact on the solar absorption of the sand. In addition, the high calcium content leads to sand agglomeration which has significant implications on receiver design and operation. It is therefore critical to locate sand collection points with low carbonate content.
... In a fluidized bed recuperator, such as the concept proposed by Schwaiger et al. [21], two coupled fluidized beds are used to transfer the heat from the exiting particle stream to the entering particle stream to preheat the material. The solids are further heated by the hot fluidization gas that exits the reactor to reach a higher temperature level. ...
The development of novel thermal energy storage concepts is of great importance to achieve the shift towards sustainable energy systems. Due to the volatile nature of renewable energy resources the interest in storage methods in order to match the intermittent output with costumer demand has increased rapidly. Thermochemical energy storage is a very promising alternative to latent and sensible thermal energy storage systems, mainly because of the high energy density per volume and the possibility of nearly loss-free storage at ambient temperature. In this paper a concept utilizing solid-gas reactions and a cascaded system of fluidized bed reactors for waste-heat recovery of gas compressor stations is presented. Due to the isothermal operation of reactor, it is not possible to cool the heat source beyond the temperature level that is defined by the storage material. Therefore, it is advantageous to use a combination of materials to obtain high heat-recovery effectiveness and minimize exergy losses. Kinetic and equilibrium models for the reactors are used in order to determine the temperature levels of energy storage and release. The mass and energy balances are solved to obtain the required amount of the storage material and to calculate the mass-flow and the temperature of the fluidization gas. Also all peripheral systems (fluidization gas compressors, heat exchangers and pumps) are taken into account for an energy assessment. Two variants of a heat storage process are proposed. The first variant uses a configuration where only the heat from the fluidization gas is recovered. The second variant includes a fluidized bed recuperator to recover the heat from the produced solid mass stream. It is concluded that by recovering the heat from the particles that exit the reactors and using it to heat up the entering solid stream, a heat output increase of 34,8% is achieved.
