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Verification of hydrothermal stability of adsorbent materials for thermal energy storage
International Journal of Energy Research
Abstract
This paper presents an experimental protocol for the cycling stability of adsorbent materials for thermal energy storage (TES) applications under hydrothermal conditions. Two different aging conditions were identified, namely, cycle and shelf test. The former one mimicking the cycling between desorption and adsorption conditions, while the latter one keeping a constant temperature for long time under constant water vapor pressure. A flexible experimental setup was then designed and realized to contemporarily perform both aging condition under selectable operating conditions. The protocol defines different characterization methods to compare the fresh and the aged samples. The measurement of the water vapor adsorption equilibrium isobars represents the main parameter to directly highlight possible degradation phenomena. Subsequently, X‐ray diffraction patterns (XRD), nitrogen physisorption, and scanning electron microscopy coupled to energy dispersive x‐ray (SEM–EDX), are used to evaluate structural, textural, morphological, and elemental composition variation that can help in identifying the causes of possible degradation. The proposed protocol was employed to validate the stability of a commercial adsorbent, AQSOA Z02, that proved a quite stable behavior both under cycle and shelf investigated conditions.
... ZIF-90s prepared in acetone-water mixture by conventional and microwave-assisted synthesis were further investigated to determine their hydrothermal stability between adsorption temperature of 30 °C and desorption temperature of 100 °C at water vapor pressure of 12.5 mbar. These conditions are usually used for low-temperature adsorption thermal battery [41,42] in applications such as building space heating. Prior to the cyclic tests, samples were degassed at 120 °C for 4 h. ...
... ZIF-90s prepared in acetone-water mixture by conventional and microwave-assisted synthesis were further investigated to determine their hydrothermal stability between adsorption temperature of 30 • C and desorption temperature of 100 • C at water vapor pressure of 12.5 mbar. These conditions are usually used for low-temperature adsorption thermal battery [41,42] in applications such as building space heating. Prior to the cyclic tests, samples were degassed at 120 • C for 4 h. ...
... Prior to the adsorption experiments, samples were degassed at 120 • C for 4 h. The cyclic stability tests were performed with the sequential procedure of water uptake measurements at 30 • C, under humid nitrogen gas flow (250 mL/min and 80% relative humidity) for 4 h, followed by desorption at 100 • C in dry nitrogen flow for 4 h, which is typical for adsorption thermal battery applications [42]. A desorption temperature of 100 • C can be attained by solar thermal collectors, while adsorption temperature of 30 • C is sufficient for space heating applications. ...
Zeolitic imidazolate frameworks (ZIFs) are traditionally synthesized using N, N-dimethylformamide (DMF). However, DMF is toxic and hazardous to human health and the environment, hence other alternative solvents need to be considered. Herein, three different solvents like methanol, water and acetone were used to replace DMF and to explore the syntheses of ZIF-90 using a conventional and a microwave-assisted solvothermal method to obtain hydrothermally stable products, which also exhibit an increased water uptake. Pure ZIF-90 was synthesized under ambient pressure at 60 °C for 90 min using the conventional solvothermal method in an acetone–water solution, while under microwave irradiation it was formed in only 5 min at 80 °C. Altering methanol, water and acetone in the reaction mixture significantly affected the structural and water adsorption properties of ZIF-90s, which were monitored via PXRD, TGA, nitrogen and water sorption, and SEM. The highly efficient, less toxic, low-cost and activation-free microwave synthesis resulted in the formation of ZIF-90 nanoparticles that exhibited the highest maximum water adsorption capacity (0.37 g/g) and the best hydrothermal stability between water adsorption at 30 °C and desorption at 100 °C at 12.5 mbar among all the products obtained.
... The thermodynamic analysis in the preceding publication showed that highly concentrated LiCl solutions (20 mol/kg) could improve the exergy efficiency to more than 40 % [28], but this is impossible to achieve with current membranes, which are optimised for sodium chloride solutions. The ADRED system could also provide cooling as useful output by switching the material from silica gel to AQSOA Z01/Z02 [75], which are commercial zeolites [76] that maintain a constant SDWP even at low evaporator temperatures [77]. ...
... From Fig. 8 showing high water capacities require regeneration temperatures well above 40°C, e.g. MOF materials (90°C) [79,80] or zeolites AQSOA Z01 and Z02 (60°C and 80°C) [76,77]. Ionogels show outstanding performances at regeneration temperatures as low as 25°C. ...
Steam power plants release more than half of the primary energy input as ultra low temperature heat below 40∘C into the environment causing thermal pollution. The emitted heat has a very low exergy content making it challenging to use as heat input by another process. Adsorption desalination combined with reverse electrodialysis can be powered by this heat and convert it into electricity. Thus, the system can mitigate thermal pollution and generate electricity at the same time. This study combines a validated reverse electrodialysis model with a dynamic adsorption desalination model that is validated with experimental data within this work. The experiments were conducted using a small‐scale adsorption desalinator and silica gel proving the feasibility of the regeneration at heat source temperatures as low as 40∘C. The simulations of the integrated system analyse different heat integration scenarios showing exergy efficiencies up to 15% and energy efficiencies up to 0.55%. Hence, the system could generate 65 kW electricity from a 20 MW heat source considering pumping losses. Waste heat as low as 40∘C converted into electricity. System provides cooling to the steam cycle process. Experiments proving that silica gel can be regenerated at 40∘C. Experimentally validated model for each component. Improving the performance ratio of adsorption desalination PR > 1. Exergy efficiency up to 15% for waste heat at 40∘C.
... The present paper started from the above reported characterization protocol, making use of a novel aging experimental apparatus proposed by Frazzica and Brancato,30 to age different zeolite foam samples in order to verify both adsorption capacity and mechanical features. In particular, up to 1500 cycles under typical working conditions were performed and compression testing was selected as mechanical method to evaluate the stability of the different foam compositions investigated. ...
... An experimental apparatus, specifically designed and realized, was used in order to apply the accelerated aging conditions. The plant is described in detail in Ref. 30 . ...
This article evaluates the hydrothermal and mechanical stability of an adsorbent composite foam based on zeolite silicone for application in adsorption heat pump. The adsorption properties of the fresh composite adsorbents and their morphological features were already presented in previous papers. In the present work, hydrothermal aging of composite foams, at varying SAPO‐34 zeolite contents and under real operating conditions, was carried out in order to verify the stability of the synthetized material. This improvement of knowledge is a key point for the industrial application. This evaluation was successfully performed by means of adsorption measurements and compression test on aged samples, up to 1500 aging cycles. The adsorption properties of composite foams are effective and stable up to the maximum number of cycles of the aging process. Instead, from the mechanical point of view, composite foams with high content of zeolite, aged at long cycles, evidenced a slight stiffening that stimulates mechanical brittle behavior. The composite foam with 67% zeolite filler represents a threshold value beyond which the action of the hydrothermal aging implies a significant loss of flexibility and mechanical integrity, which limits its applicability under typical conditions. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48311.
... Substitutes include coir fibre grains, quantitative cotton form, carbon black, and other organic nanoscale liners. One purpose of nanostructure would be to improve polymer-reinforcement adhesion [11]. Because nanoscale substances aim to form clusters in the matrices, employing nanoscale substances gives a regularly dispersed challenge in a biocomposite containing natural fibres with nanoparticle filler; moisture content decreases while mechanical performance increases. ...
This article explores the impact of nano-silica on the properties of woven flax fibre/epoxy composites. Using compression moulding, epoxy/flax/silica hybrid nanocomposites were produced. The nano-silica was dispersed in the epoxy matrix via ultrasonication at various weight ratios. A series of tests, including crack durability, dynamic mechanical analysis, and scanning electron microscopy, were conducted to evaluate the modified materials. Notably, a 3% nano-silica filler load resulted in a 54% and 57% improvement in initiation and transmission interfacial fracture toughness, respectively. Scanning electron microscope imaging confirmed that fibres pull out at the crack tip during initial debonding, accounting for the increased toughness. Dynamic mechanical analysis further revealed enhancements in mechanical properties. Moreover, the 3% nano-silica content led to less fibre pull-out, suggesting higher heat resistance than standard flax/epoxy composites. The material also demonstrated promising antimicrobial efficacy against gram-positive and gram-negative bacteria, offering a potential alternative to conventional antibiotics.
... There are three techniques for producing activated charcoal. The catalytic cracking of a precursor in an innocuous flow at temperatures up from 500 to 1000 degrees Celsius results in char creation [20,21]. The charcoal is then ignited in an oxidising gas like carbon dioxide and vapour at temperatures ranging from 700 to 1300 degrees Celsius. ...
With significant benefits over many other commercialised thermal storage methods, activated carbon fiber (ACF) is believed to be among the finest biosorbents for adsorbent purposes. If correctly made, it is an outstanding mesoporous lightweight material with micropores and, in most cases, no micropores. ACF’s higher bulk densities and great dynamic capacity demonstrate its value and are used in adsorbent technologies. The present study’s primary goal is to create active carbon fiber from organic hemp fiber. The following parameters were selected: (i) activating temperatures, (ii) activating timing, (iii) carbonization temperature, (iv) activating ingredient %ages, and (v) speed of activation temperature, all with four levels to achieve the goal. Taguchi optimization techniques were used to optimize the adsorbent characteristics. The current study used an L16 orthogonal array to accomplish that improvement. According to the previous Taguchi, the optimal conditions were 300°C combustions, insemination with 22.5% w/v K2HPO4 solution, and activating at 800°C for 3 hours at 20°C/min. The greatest contribution is 54.75%, followed by the rate of temperature activation at 23.35%, carbonated temperature at 10.14%, duration of stimulation at 8.82%, and H3PO4 concentrations at 2.94%. The results show that the activation temperature and rate of the temperature of activations are the essential elements in the current study’s accomplishment of the best adsorption capacities.
... The sorption/desorption cycling performance [38] of the W-46-CaCl 2 and W-46-LiCl composites were carried out on IGAsorp-XT automated water sorption gravimetrical analyser (the accuracy ±0.1 µg) (Hiden Isochema Ltd., Warrington, UK.) with the sequential procedure of water uptake measurements at 35 • C (the accuracy ±0.1 • C) under moist nitrogen gas flow (flow rate of 250 mL/min and 80% relative humidity) for 3 h, followed by drying at 100 • C with dry nitrogen flow for 2 h. The sequence was repeated 25 times according to the literature [40] at a desorption temperature of 100 • C, which can be attained by solar thermal collectors. The sorption temperature was fixed to 35 • C, which is sufficient for space heating applications. ...
The efficiency of thermochemical heat storage is crucially determined by the performance of the sorbent used, which includes a high sorption capacity and a low regeneration temperature. The thermochemical salt hydrate– γ-alumina composite sorbents are promising materials for this application but lack systematic study of the influence of γ-alumina structural properties on the final storage performance. In this study, mesoporous γ-Al2O3 supports were prepared by solvothermal and hydrothermal synthesis containing a block copolymer (F-127) surfactant to design thermochemical CaCl2 and LiCl composite water sorbents. Altering the solvent in the synthesis has a significant effect on the structural properties of the γ-Al2O3 mesostructure, which was monitored by powder XRD, nitrogen physisorption, and SEM. Solvothermal synthesis led to a formation of mesoporous γ-Al2O3 with higher specific surface area (213 m2/g) and pore volume (0.542 g/cm3) than hydrothermal synthesis (147 m2/g; 0.414 g/cm3). The highest maximal water sorption capacity (2.87 g/g) and heat storage density (5.17 GJ/m3) was determined for W-46-LiCl containing 15 wt% LiCl for space heating, while the best storage performance in the sense of fast kinetics of sorption, without sorption hysteresis, low desorption temperature, very good cycling stability, and energy storage density of 1.26 GJ/m3 was achieved by W-46-CaCl2.
... Such materials offer the benefits of high density for storing the heat, a considerable raising of the temperature, and the ability to store the reagents (sorbent and sorbate) at room temperature without auto-discharge, which is an important feature for applications in seasonal storage. Referring to [112][113][114][115], TCHS materials should meet many criteria as follows: ...
Recent contributions to thermochemical heat storage (TCHS) technology have been reviewed and have revealed that there are four main branches whose mastery could significantly contribute to the field. These are the control of the processes to store or release heat, a perfect understanding and designing of the materials used for each storage process, the good sizing of the reactor, and the mastery of the whole system connected to design an efficient system. The above-mentioned fields constitute a very complex area of investigation, and most of the works focus on one of the branches to deepen their research. For this purpose, significant contributions have been and continue to be made. However, the technology is still not mature, and, up to now, no definitive, efficient, autonomous, practical, and commercial TCHS device is available. This paper highlights several issues that impede the maturity of technology. These are the limited number of research works dedicated to the topic, the simulation results that are too illusory and impossible to implement in real prototypes, the incomplete analysis of the proposed works (simulation works without experimentation or experimentations without prior simulation study), and the endless problem of heat and mass transfer limitation. This paper provides insights and recommendations to better analyze and solve the problems that still challenge the technology.
... According to the discussion above, XS could bear a temperature up to 300 • C which ensures its application in this high-temperature heat pump system. Other than heat pumping, adsorbent materials for thermal energy storage and transformation are also expected to show a good hydrothermal stability when subjected to the high-water vapor relative pressure [38]. The experiment cycle of this direct-contact heat exchange heat pump would test the hydrothermal characteristics of the various zeolite samples. ...
High-temperature steam has been directly generated from hot water based on a solid sorption heat pump system by employing silane functionalized zeolite 13X (XS). The adsorbent is prepared by a liquid phase grafting method to modify functional groups on the zeolite surface with a silane coupling agent. The static water contact angle (WCA) and surface functional groups are analyzed by optical contact angle measuring instruments and Fourier transform infrared spectroscopy (FTIR), respectively. Analytical results confirm the successful preparation of surface hydrophobic zeolite. The water adsorption capacity of XS is slightly less than that of 13X, while the overall adsorption heat remains almost constant. Dry air at 130 °C is utilized for the regeneration of the wet zeolite in cyclic experiments. Steam at 207 °C is generated from input hot water at 72 °C in a packed bed filled with XS-25 (zeolite 13X functionalized by a saline solution concentration of 25%). The thermal response during the steam generation process is accelerated by utilizing XS. The mass of steam product does not change during the generation with XS, whereas cyclic time is shortened. Moreover, XS facilitates the regeneration process by decreasing the heat demand for the removal of free water. System evaluation results show that a higher Sp (steam productivity) is obtained for XS than that for zeolite 13X. COPh (coefficient of performance for heating) and SHP (specific heating power) are elevated by 23.6% and 5.7% for XS compared with those for zeolite 13X, respectively.
... 7 Porous materials such as silica gels or zeolites have been used as chemical components for water adsorption/desorption. 8,9 These materials possess a relatively low heat storage capacity compared to the hydration type, but exhibit high structural and volumetric stabilities after many working cycles. 10 Salt hydrates, as alternative materials for TCHS, can produce large amount of heat-up to 8 to 10 times higher than that of SHS and 2 to 3 times more compared to LHS. 3 10,11 These salt hydrates exhibit excellent storage potentials, but the charging/discharging cycles cannot run seamlessly because of deliquescence, swelling, and agglomeration phenomena. ...
Ferroaluminophosphate (FAPO4‐5)/MgSO4 composites were prepared as a series of new materials with low charging temperatures and improved volumetric heat storage capacities. A microporous zeolithic compound FAPO4‐5 was used as an adsorbent of water vapor and a matrix of MgSO4 salt particles. Composites with various MgSO4 contents (5‐40 wt%) were then prepared using a wet impregnation method. The MgSO4 salt particles were impregnated into the micropores and textural pores of FAPO4‐5 without the crystal structure of the host material, confirmed by XRD patterns. Although nitrogen adsorption isotherms of the composites showed approximately a half of FAPO4‐5 pore was blocked by MgSO4, the water uptake of the composites reached the sum of those from FAPO4‐5 and MgSO4. The dehydration temperature of MgSO4 in the FAPO4‐5 matrix decreased with its decreasing content due to the easier dehydration of FAPO4‐5. The heat storage recovery of the 25 wt% loaded sample at 80°C was 85.5% while that of MgSO4 was 52.2%. The swelling and agglomeration of the composites containing 25 wt% and less salt were suppressed by the micro and textural pores of FAPO4‐5. The composite at 25 wt% of MgSO4 loading exhibited a total volumetric heat storage capacity of 174 kW h m−3 based on the volume in the hydrated state. Composites with various MgSO4 contents (5‐40 wt%) in the micropore and textural pore of a ferroaluminophosphate (FAPO4‐5) were prepared using a wet impregnation method. Limited swelling of the confined MgSO4 salt particles in the pore allowed the composites to exhibit highly improvement of volumetric heat storage capacity. Moreover, the dehydration temperature of MgSO4 in the composites decreased due to the easier dehydration of FAPO4‐5 and thus heat storage recovery at low temperature was improved.
... A protocol for characterizing hydrothermal stability. The experimental ageing setup used in this work has been described elsewhere 40 . It consists in a vacuum chamber and in a glass evaporator/condenser; inside the vacuum chamber, three plate heat exchangers (HEX) are located to define the ageing conditions of the samples. ...
The lack of robust and low-cost sorbent materials still represents a formidable technological barrier for long-term storage of (renewable) thermal energy and more generally for Adsorptive Heat Transformations—AHT. In this work, we introduce a novel approach for synthesizing cement-based composite sorbent materials. In fact, considering the number of available hygrosopic salts that can be accommodated into a cementitious matrix—whose morphological properties can be also fine-tuned—the new proposed in situ synthesis paves the way to the generation of an entire new class of possible sorbents for AHT. Here, solely focusing on magnesium sulfate in a class G cement matrix, we show preliminary morphological, mechanical and calorimetric characterization of sub-optimal material samples. Our analysis enables us to theoretically estimate one of the most important figures of merit for the considered applications, namely the energy density which was found to range within 0.088–0.2 GJ/m3 (for the best tested sample) under reasonable operating conditions for space heating applications and temperate climate. The above estimates are found to be lower than other composite materials in the literature. Nonetheless, although no special material optimization has been implemented, our samples already compare favourably with most of the known materials in terms of specific cost of stored energy. Finally, an interesting aspect is found in the ageing tests under water sorption-desorption cycling, where a negligible variation in the adsorption capability is demonstrated after over one-hundred cycles.
... Metal particles coating are extensively used for surface coating in a wide range of application including thermal management of electronics, concentrating photovoltaics, sensors, environmental applications and nuclear power plants. 1,2 Numerous micro and nano-scale surface modification technique have been applied, in literature for phase change heat transfer augmentation, including uniform porous coatings, 3,4 modulated microporous structures, 5 nanostructures, 6-8 rough surface, 9 micro-channels, 10 and foams. 11 Due to integration, multi-functionality and compaction of future devices such as automation, sensing, power generation and electronics, management of high heat loads have an increasing trend. ...
Metal particles coating is extensively used for surface coating a wide range of application including thermal management of electronics, concentrating photovoltaics, sensors and nuclear power plants. Both micro and nano‐scale surfaces have been proven to show an enhanced two‐phase heat transfer performance by varying surface properties like area, wettability, and roughness. To combine the unique features of both micro and nano‐scale surface coatings, this study presents the design, synthesis, and characterization of new hybrid micro‐nano scale surface coating by a new two steps approach. Five different types of surfaces; namely, plain nanocoated (PNC), uniform micro‐porous (UMP), uniform hybrid micro‐nano porous (UHMNP), 2‐D modulated microporous (MMP) and modulated hybrid micro‐nano (MHMNP) surfaces were fabricated. A new two steps approach of hot‐pressing followed by nucleate boiling is used for the fabrication of these surfaces. Successful coating of hybrid micro‐nano scale coating was achieved. Considering the critical surface properties of micro and nanoscale coatings, new hybrid micro‐nano surfaces have been characterized for SEM, wettability, roughness test. The comparative analysis of these new hybrid coating is also performed with micro coated and uncoated surfaces. With the coating of nanoparticles, the average roughness of PNC surface increased by 4.67 times and that of hybrid micro‐nano particle surface by 2.3 times. The deposition of nanoparticles resulted in an increase in contact angle for PNC surface, while the contact angle of hybrid micro‐nano surfaces decreases from 126.4° to 82.1°.
... Metal particles coating are extensively used for surface coating in a wide range of application including thermal management of electronics, concentrating photovoltaics, sensors, environmental applications and nuclear power plants. 1,2 Numerous micro and nano-scale surface modification technique have been applied, in literature for phase change heat transfer augmentation, including uniform porous coatings, 3,4 modulated microporous structures, 5 nanostructures, 6-8 rough surface, 9 micro-channels, 10 and foams. 11 Due to integration, multi-functionality and compaction of future devices such as automation, sensing, power generation and electronics, management of high heat loads have an increasing trend. ...
Herein, magnesium-aluminum layered double hydroxides (Mg-Al-LDH) were synthesized by an environmentally friendly and economically promising hydrothermal technique for the adsorption of reactive green 5 (RG5) dye. To further enhance the...
Thermochemical heat storage is currently regarded as the most promising technology with capability of the systems to conserve the thermal energy as long as desired without heat losses due to their reversible sorption and chemical reactions. Design of efficient storage sorption materials with advanced properties is motivated by two driving forces: to increase of the energy storage density and to regenerate the sorbent at low temperature (80–140°C). Since the beginning, highly hydrophilic zeolites and weak hydrophilic silica gels with water vapor systems have been one of the most studied and tested adsorbent/adsorbate pairs for application in thermo‐chemical heat storage. However, zeolites require high temperature for desorption (>200°C), while silica gels need lower desorption temperatures (~100°C), and both adsorbents have a low water loading within a adsorption/desorption cycle. Thus, an optimal sorption material should provide a moderate affinity toward water molecules that depends on particular operating conditions of the cycle. This chapter reviews sorption material developments on zeolites, aluminophosphates, metal organic frameworks (MOFs) and two‐component sorbents (composites) containing porous matrices from zeolites to new mesostructured iron silicate and salt hydrates with high energy storage density. The developments in materials research promise novel and high performance storage materials in near future.
A novel and unique heat energy storage system is introduced in this work in the context of energy balancing of renewable sources of energy. Many of the market competitive renewable sources of energy have difficulties with continuous energy production which creates specific demands on the electric grid and brings up the necessity for some sort of energy management. In this paper, we discuss the properties of adsorption heat energy storage technology as a novel way for short to long-term energy storage improving the utilisation of renewable sources of energy. The utilization of surplus energy from the renewable energy source is discussed in the example of solar photovoltaic (PV) panels and solar collectors.
The adsorption performance of the thermal energy storage (TES) system changes depending on the material properties of the adsorbent itself, but the change of the hardware structure can also substantially change the adsorption characteristics. In this study, a laboratory‐scale adsorption‐based TES system was constructed, and the adsorption performance of three adsorbents was evaluated in the same system to compare the adsorption performance between adsorbents. The adsorption characteristics of silica gel, zeolite 13X, and 4A, which are the most preferred adsorbents in the physical adsorption‐based TES system, were selected for evaluation. Experiments with each adsorbent were performed, including heat recovery to evaluate the heat transfer effect and the amount of heat recoverable in the actual TES system. Experimental results have identified several key characteristics of the adsorption and performance of each adsorbent in the TES system, as well as operating parameters that determine the influence of adsorption performance on the TES system.
The actual energy storage density of the adsorbent is affected not only by the enthalpy of adsorption of the material itself but also by other factors. These factors include the difference in thermal conductivity that causes a difference in temperature distribution and the magnitude of mass transfer resistance due to the shape of the adsorbent particle and the actual TES system reactor structure. If the reaction heat generated during the adsorption reaction cannot be effectively released, the adsorption performance is significantly lowered due to the increased temperature of the reactor inside. This phenomenon was commonly observed in adsorbents examined in the present study. The uptake amount, X [g/g], was increased by allowing the inside of the reactor to be maintained at a lower temperature through heat recovery. In case of silica gel, the temperature rise during adsorption reaction is not high due to the difference of isotherm characteristics compared with zeolites, but it is possible to absorb more amount of adsorbate and to recover heat for a longer time. The energy storage density is affected by the temperature increase effect and the uptake amount of adsorbate during the adsorption reaction. The experimental results show that the energy storage density of zeolite 13X is 15% and 28.7% higher than that of silica gel and 4A, respectively, and the temperature rise due to heat generation during adsorption reaction is also high, which is advantageous in adsorption TES system performance.
The increasing concerns about climate change and environmental emissions have led to conservation of energy in buildings through the development of several energy-efficient technologies. Though, the energy requirements in buildings are being continuously addressed, factually, the buildings across the world consume almost one-third to one-quarter of the total energy being produced. From this perspective, the development and incorporation of the energy efficient materials and technologies in buildings in order to fulfill the cooling energy requirements have been gaining impetus, in recent years. The building envelopes which may seem to be consuming more energy can be modified by tailoring the construction materials, such as mortar, with heat storage materials for regulating the indoor temperature and achieving enhanced energy efficiency as well. The phase change material (PCM)-based thermal energy storage (TES) is one among the efficient technologies available, which seems viable to cater to the end-use energy demand through energy redistribution. This is possible because of the storage and retrieval of the latent heat during the phase change processes at nearly isothermal conditions. The prime intention of this article is to review the literature involving synergy of PCM and mortar for achieving energy efficiency in buildings. The review includes details regarding different PCM-mortar combinations along with details pertaining to, but not limited to, thermal and mechanical properties of the PCM-mortar. The period, post 2010, has been observed to be very productive with many researchers actively carrying out the investigations related to this very important area of research and hence the period between 2010 and 2017 has been specifically chosen for this review article. The selection and application of a variety of the PCM-mortar combinations in buildings have been extensively reviewed from the perspectives of porosity, supporting materials, thermal and structural properties. Furthermore, the advantages and limitations associated with each kind of mortar for its utility as PCM carrier have also been summarized.
The multistep sorption-reaction cycle utilizes heat from several processes, such as absorption, dilution, crystallization reaction, and thermochemical reaction. So, it is very attractive to use multistep sorption technology to improve the performance of temperature transmitter, air conditioning, and heat pump. Different working pairs of silica gel/LiCl, activated carbon/LiCl multiwalled carbon nanotubes/LiCl, and multiwalled carbon nanotubes/CaCl2 are tested and compared. The results show that the water uptake of these compound adsorbents varies with different salt mass fraction. The water uptake goes up dramatically at the crystallization and deliquescence point. Compared with the energy storage performance under the same working conditioning, the activated carbon/LiCl has the best performance, and the possible reason is that the activated carbon has the largest specific surface and the smallest average pore diameter.
This paper gives a comprehensive review on recent developments and the previous research studies on cold thermal energy storage using phase change materials (PCM). Such commercially available PCMs having the potential to be used as material for cold energy storage are categorised and listed with their melting point and latent heat of fusion. Also techniques for improving the thermo-physical properties of PCM such as heat transfer enhancement, encapsulation, inclusion of nanostructures and shape stabilization are reviewed. The effect of stability due to the corrosion of construction materials is also reported. Finally, different applications where the PCM can be employed for cold energy storage such as free cooling of building, air-conditioning, refrigerated trucks and cold packing are discussed.
Mobile energy storage systems working with Zeolite in an open sorption system can utilize industrial waste heat in cases where a pipeline bound connection is not cost sufficient. A demonstration plant using extraction steam from a waste incineration plant to charge the storage with 130°C hot air and an industrial drying process as customer 7km far away from the charging station was built, operated and monitored over one year. The storage contains 14 tons of Zeolite and uses at the discharging station exhaust air from the dryer with 60°C and 0.09kg/kg humidity to realize a storage capacity of 2.3 MWh, saves 616kg carbon dioxide per cycle and shows no degradation within accuracy of the measuring equipment. Maldistribution through the packed bed of zeolite prohibit the desired power output. The prime energy costs can be reduced down to 73 €/MWh considering a small scale mass production.
Thermal energy storage based on adsorption and desorption of water on an adsorbent can achieve high energy storage densities. Many adsorbents lose adsorption capacity when operated under unfavourable hydrothermal conditions during adsorption and desorption. The stability of an adsorbent against stressing hydrothermal conditions is a key issue for its usability in adsorption thermal energy storage. We built an experimental setup that simultaneously controls the hydrothermal conditions of 16 samples arranged in a matrix of four temperatures and four water vapour pressures. This setup allows the testing of potential adsorbents between temperatures of 50 °C and 350 °C and water vapour pressures of up to 32 kPa. A measurement procedure that allows the detection of the hydrothermal stability of an adsorbent after defined time spans has been designed. We verified the functionality of the multiple sample measurements with a microporous adsorbent, a zeolite NaMSX. The hydrothermal stability of this zeolite is tested by water uptake measurements. A standard deviation lower than 1% of the 16 samples for detecting the hydrothermal stability enables setting different conditions in each sample cell. Further, we compared the water uptake measurements by measuring their adsorption isotherms with the volumetric device BELSORP Aqua 3 from Bel Japan.
Sorption thermal energy storage (STES) technology, belonging to the wider class of thermochemical TES, represents a promising alternative to common sensible and latent TESs, especially for applications at low-medium temperature (i.e. below 130 °C). The interest towards this technology is confirmed by the huge amount of research and development activities ongoing, represented by scientific publications as well as funded projects and international working groups.
In such a context, the present paper reports about the most recent activities in the STES field. Particularly, it focuses on the analysis of innovative sorbent materials currently under development, comprising liquid absorption, physical adsorption, chemical reactions in pure salts and composite sorbents. Analysis of critical issues like achievable storage density, stability and corrosiveness were reported for each sorbent material.
Furthermore, prototypes recently developed for each of the sorbent classes above reported were presented, highlighting the achievable performance, with particular attention towards the TES density attained under typical working conditions for heat and cold storage applications, both with open and closed TES systems.
Finally, the most recent international activities focusing on the further development of STES, to help achieving higher Technology Readiness Level (TRL) were reported. These mainly comprise funded R&D projects and international working groups supported by intergovernmental organizations and research and innovations alliances.
An innovative design of a mobile thermal battery resembling the solar receiver is presented. A ternary salt mixture consisting of 52% KNO3, 18% NaNO3, and 30% LiNO3 by wt% is used as the thermal energy storing medium inside the thermal battery. Since the thermal conductivity of the ternary salt mixture is low, aluminum meshes are introduced to create a thermal conduction tree inside the thermal energy storing medium. The actual field data are used in the simulations to resemble the solar irradiation emanating from the parabolic trough and focusing onto the thermal battery outer surface. To improve the uniform heating at the outer surface, the thermal battery rotation along the centerline of the trough is considered. The temperature parameter is introduced to assess the uniform‐like temperature distribution inside the ternary salt mixture. It is found that the use of aluminum meshes improves the heat diffusion in the phase change material of the ternary salt mixture; in which case, it acts like a thermal conduction tree inside the thermal battery. The rotation of the thermal battery results in uniform‐like temperature distribution across the thermal battery cross section and suppresses the excessive temperature rise because of the local heating in the close region of the thermal battery outer surface.
This paper presents the experimental characterisation of three zeotype materials, namely, AlPO-18, FAPO-34 and SAPO-34, suitable for adsorption heat transformation applications, employing water as refrigerant. Morphological and thermo-physical analyses were performed on each sample. In particular, the adsorption capacity of each material was evaluated by measuring a complete set of water vapour adsorption/desorption isotherms, in order to investigate the hysteresis effect. The obtained equilibrium data were fitted by means of Dubinin-Astakhov equation, both for adsorption and desorption branches. Finally, a thermodynamic analysis of the achievable performance of these three working pairs was performed under three main operating conditions, namely, thermal energy storage, air conditioning and heat pumping. The achieved results confirmed the potentiality of these adsorbents, showing promising cooling and thermal COP, up to 0.80 and 1.60 respectively, and heat storage capacities both for daily and seasonal operation.
Zeolite 13X, a hydrophilic adsorbent, can be used for storing thermal energy. However, its crystallinity can degrade under hydrothermal stress in the aqueous atmosphere of an adsorption storage device. This would result in a loss of energy storage capacity. There is still no known method for predicting the long-term hydrothermal stability of zeolites under relevant adsorption storage conditions. A solution for this could be a kinetic model designed with experimental data to predict hydrothermal degradation. The objective of the present study was to examine the hydrothermal stability of zeolite 13X under relevant adsorption storage conditions and to analyze its degradation in respect to the influencing factors of water vapor pressure, temperature and period of treatment. The investigated zeolite 13X powder and zeolite 13X beads have been treated at temperatures between 200 and 350 °C and water vapor pressures up to 31 kPa for treatment periods of up to 312 h. We have analyzed the changes in the zeolite structure, composition and adsorption properties by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, ²⁷Al/²⁹Si MAS NMR spectroscopy, molybdate method and water sorption. The results show a degradation of the crystalline zeolite 13X phase into an amorphous phase under all hydrothermal conditions, although to different degrees. Under specific hydrothermal conditions a portion of the primary crystalline phase withstands further treatment. Based on chemical decomposition mechanisms, we discuss this phenomenon. The complex stability behavior of the zeolite 13X demonstrates that a prediction beyond experimental data cannot be recommended.
The shortage in energy resources combined with the climb in greenhouse emissions is the main incentive beyond the deployment of solar energy resource in various applications. One of the most successful applications is the utilization of solar energy in the domestic water heating systems (DWHS) because 70% of the consumed energy in the residential segment is utilized for space heating and appliances in cold climates [1]. However, the full deployment of solar energy in domestic water heating is only possible when an energy storage system with acceptable price is available. Recently a new tendency for deploying phase change materials (PCMs) as an energy storage system is introduced in several solar DWHS. These systems are known as integrated PCM in solar DWHS and offer several advantages including high storage capacity, low storage volume, and isothermal operation during the charging and discharging phases. The present study reviews various techniques utilized for integrating the PCM in solar water heating systems and the utilized methods for enhancing the heat transfer characteristics of the PCM through the usage of extended surfaces and high conductive additives.
Zeolite scientists, whether they are working in synthesis, catalysis, characterization or application development, use theAtlas of Zeolite Framework Typesas a reference. It describes the main features of all of the confirmed zeolite framework structures, and gives references to the relevant primary structural literature. Since the last edition 34 more framwork types have been approved and are described in this new edition. A further new feature will be that characteristic building units will be listed for each of the framework types. Zeolites and their analogs are used as desiccants, as water softeners, as shape-selective acid catalysts, as molecular sieves, as concentrators of radioactive isotopes, as blood clotting agents, and even as additives to animal feeds. Recently, their suitability as hosts for nanometer spacing of atomic clusters has also been demonstrated. These diverse applications are a reflection of the fascinating structures of these microporous materials. Each time a new zeolite framework structure is reported, it is examined by the Structure Commission of the International Zeolite Association (IZA-SC), and if it is found to be unique and to conform to the IZA-SC's definition of a zeolite, it is assigned a 3-letter framework type code. This code is part of the official IUPAC nomenclature for microporous materials. The Atlas of Zeolite Framework Types is essentially a compilation of data for each of these confirmed framework types. These data include a stereo drawing showing the framework connectivity, features that characterize the idealized framework structure, a list of materials with this framework type, information on the type material that was used to establish the framework type, and stereo drawings of the pore openings of the type material. * Clear stereo drawings of each of the framework types * Description of the features of the framework type, allowing readers to quickly see if the framework type is suitable to their needs * References to isotypic materials, readers can quickly identify related materials and consult the appropriate reference.
Thermochemical energy storage (TCES) systems utilize reversible reactions to store solar energy in chemical form. The present work focuses on the cobalt/cobaltous oxide (Co3O4/CoO pair) based redox cycle in which the active oxide is coated on a cordierite honeycomb structure. During the redox cycle, cobalt oxide uptakes and releases oxygen from/to an air stream coming in direct contact with it. Thus air acts as a reaction medium as well as a heat transfer fluid (HTF). In this configuration, the storage material works as a heat storage medium and also a heat exchanger. A two-dimensional, axisymmetric numerical model to simulate the heat and mass transfer and the chemical reaction in the thermochemical heat storage reactor has been developed. Experimental results from a 74 kW hth-capacity prototype reactor installed at the Solar Tower Jülich test facility, Germany, were used to validate the numerical model. The time-dependent boundary conditions in the form of inlet temperature and inlet mass flow rate from the experiments were employed in the numerical model. The temperatures of the redox material at different locations inside the prototype thermochemical storage/heat exchanger reactor were used for the numerical model validation. Total energy stored/released (sensible as well as chemical) during the experiments was also compared with the numerical model results. From this study, it is concluded that the numerical model can accurately predict charging/discharging processes for the cobalt oxide based thermochemical storage reactor system for multiple redox looping cycles. The model allows a better understanding of the complete process and helps to identify the effect of variation of boundary conditions on the system.
As one of the most promising thermochemical energy storage medium, research on the Ca(OH)2/CaO system provides an important way of understanding energy storage/release rates of the entire energy storage system. In this paper, a high-precision thermogravimetric analysis is adopted to investigate thermal decomposition processes of the Ca(OH)2 samples in pure N2 atmosphere at different heating rates. The results demonstrate that during the thermal decomposition process, two weight loss processes respectively occur during 623.15 ~ 773.15 and 873.15 ~ 973.15 K, and the weight loss rates are close to 21% and 2% severally. Multi-heating rate methods are applied to the study of thermal decomposition dynamics. Findings show that the obtained kinetic parameters are related to reaction conversion, heating rate, and the chosen model-methods. To further understand the decomposition mechanism of Ca(OH)2, differential method, integral method, and multiple scanning method are used to deal with the experimental data. Through the most probable mechanism function analysis, under certain experimental conditions, thermal decomposition kinetics model of Ca(OH)2 accords well with the shrinking cylinder mechanism. These conclusions provide theoretical bases for applying the Ca(OH)2/CaO system to the thermochemical energy storage field. Copyright
Industrial activities have a huge potential for waste heat recovery. In spite of its high potential, industrial waste heat (IWH) is currently underutilized. This may be due, on one hand, to the technical and economic difficulties in applying conventional heat recovery methods and, on the other, the temporary or geographical mismatch between the energy released and its heat demand. Thermal energy storage (TES) is a technology which can solve the existing mismatch by recovering the IWH and storing it for a later use. Moreover, the use of recovered IWH leads to a decrease of CO2 emissions and to economic and energy savings. Depending on the distance between the IWH source and the heat demand, TES systems can be placed on-site or the IWH can be transported by means of mobile TES systems, to an off-site heat demand. Around 50 industry case studies, in which both on-site and off-site recovery systems are considered are here reviewed and discussed taking into account the characteristics of the heat source, the heat, the TES system, and the economic, environmental and energy savings. Besides, the trends and the maturity of the cases reviewed have been considered. On-site TES systems in the basic metals manufacturing are the technology and industrial sector which has focused the most attention among the researchers, respectively. Moreover, water (or steam), erythritol and zeolite are the TES materials used in most industries and space comfort and electricity generation are the most recurrent applications.
This paper presents a novel experimental protocol for the evaluation of the thermodynamic performance of working pairs for application in adsorption heat pumps and chillers. The proposed approach is based on the experimental measurements of the main thermo-physical parameters of adsorbent pairs, by means of a DSC/TG apparatus modified to work under saturated vapour conditions, able to measure the ads-/desorption isobars and heat flux as well as the adsorbent specific heat under real boundary conditions. Such kind of activity allows to characterize the thermodynamic performance of an adsorbent pair allowing the estimation of the thermal Coefficient Of Performance (COP) both for heating and cooling applications, only relying on experimental values. The experimental uncertainty of the method has been estimated to be around 2%, for the COP evaluation. In order to validate the proposed procedure, a first test campaign has been carried out on the commercial adsorbent material, AQSOA-Z02, produced by MPI (Mitsubishi Plastics Inc.), while water was used as refrigerant. The proposed experimental methodology will be applied on several other adsorbent materials, either already on the market or still under investigation, in order to get an easy and reliable method to compare thermodynamic performance of adsorptive working pairs.
Solar thermal power generation technology has great significance to alleviate global energy shortage and improve the environment. Solar energy must be stored to provide a continuous supply because of the intermittent and instability nature of solar energy. Thermochemical storage (TCS) is very attractive for high-temperature heat storage in the solar power generation because of its high energy density and negligible heat loss. To further understand and develop TCS systems, comprehensive analyses and studies are very necessary. The basic principle and main components of a solar TCS system are described in this paper. Besides, recent progress and existing problems of several promising reaction systems are introduced. Further research directions are pointed out considering the technical, economic, and environmental issues that existed in the wide application of TCS. Copyright © 2014 John Wiley & Sons, Ltd.
Open adsorption systems using water as adsorbate, zeolite as adsorbent and air as heat and mass carrier can be used for heating, cooling and thermal energy storage (TES). In an adsorption cycle air is dehumidified, so drying processes are a promising field of application. The objective of the work presented was to reduce the energy consumption of a dishwasher by means of an open adsorption system. The water heating phase of the main washing cycle has been used to desorb a packed bed of zeolites. The common water heating phase before the drying of the dishes has been omitted and replaced by an adsorption phase in which the dishes are dried by hot air. In this context the adsorption system was used as a thermally driven heat pump and a thermal energy storage system. The energy consumption is reduced by 25 % compared to a conventional dishwasher.
The SAPO-34 was synthesized by a hydrothermal method using diethylamine as a template. Water adsorption strength on SAPO-34 is between that on 13X and A type silica gel. During 100–400 Pa, the water uptake on SAPO-34 increases sensitively to pressure, and equilibrium water uptake reaches 0.35 kg/kg, 25% higher than 13X. SAPO-34 shows no significant reduced cyclic water uptake over 60 cycles. Most of the initial SAPO-34 phase is restored, while the regular cubic-like morphology is well maintained, and the specific surface area only decreases by 8.6%.
Alternative low cost materials are evaluated through the valorization of by-products derived from mining and metallurgical industry for solid sensible heat based energy storage systems. They were used either as received or formulated as aggregates in mortars, and their thermal and mechanical properties were characterized. A selection methodology was applied in order to compare them with available materials found in the literature for applications as (STES) materials, and with materials from Cambridge Educational Software (CES) Selector database. It was demonstrated that these recycled materials have a high potential for these thermal energy storage applications.
This paper presents novel experimental methods for verification of both hydrothermal and mechanical stabilities of adsorbent coatings. Experiments have been carried out on zeolite-based coatings over aluminum substrates, prepared by a dip-coating technique developed at CNR-ITAE. Hydrothermal aging of several adsorbent coatings is ongoing. Adsorption and structural stability of some samples under test was successfully verified after 35000 aging cycles by isobars measurement and XRD analysis. Mechanical properties of coatings have been evaluated by applying different typologies of static and dynamic mechanical stresses. Results obtained have been compared with those achieved by subjecting adsorbent coatings prepared by Mitsubishi Plastic Incorporation (MPI) to the same characterization protocol. The comparison between the two types of coating returned that MPI coatings posses similar thermal stability and better mechanical strength than CNR-ITAE coatings.
Thermally driven adsorption chillers and heat pumps are a very promising approach toward an efficient use of energy as well as an effective climate protection through reduced CO2 emission of conventional heating and cooling devices. With regard to current market entrance of this technology, this paper presents results on the stability of current available materials like silica gels and zeolites, recently developed materials like aluminophosphates (AlPO) and silica-aluminophosphates (SAPO) and novel materials like metal organic frameworks (MOF) under hydrothermal treatment.Seven materials as powders or granules as well as three composite have been analyzed under continuous thermal cycling in a water vapour atmosphere in order to evaluate their suitability for the use in a periodically working heat pump with water as working fluid.The stability of powders has been analyzed in-situ by thermogravimetry in a first stage short-cycle test. In case of the composite, made up of an active sorption material and a support structure, a cycling-test rig has been developed in order to realize a life-cycle stress. The need for a first stage short-cycle test is demonstrated impressively by the dramatic loss of 40% in sorption capacity of a Cu-BTC sample within the first 15 cycles.
A zeolite-water adsorption module, which has been originally constructed for an adsorption heat pump, has been experimentally investigated as an adsorptive thermal energy storage unit. The adsorber/desorber heat exchanger contains 13.2 kg of zeolite 13X and is connected to an evaporator/condenser heat exchanger via a butterfly valve. The flow rate of the heat transfer fluid in the adsorber/desorber unit has been changed between 0.5 and 2.0 l min−1, the inlet temperature to the evaporator between 10 and 40°C. It turned out that the higher the flow rate inside the adsorber/desorber unit the faster and more effective is the discharge of heat. However, at lower flow rates higher discharge temperatures are obtained. Storage capacities of 2.7 and 3.1 kWh have been measured at the evaporator inlet temperatures of 10 and 40°C, respectively, corresponding to thermal energy storage densities of 80 and 92 kWh m−3 based on the volume of the adsorber unit. The measured maximum power density increases from 144 to 165 kWh m−3 as the flow rate in the adsorber increases from 0.5 to 2 l min−1. An internal insulation in form of a radiation shield around the adsorber heat exchanger is recommended to reduce the thermal losses of the adsorptive storage. Copyright © 2006 John Wiley & Sons, Ltd.