Journal articles: 'Variable-Temperature Thermal Energy Storage'

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LUFT, WERNER. "High-temperature Solar Thermal Energy Storage." International Journal of Solar Energy 3, no. 1 (January 1985): 25–40. http://dx.doi.org/10.1080/01425918408914381.

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Bisio, G. "Exergy Analysis of Thermal Energy Storage With Specific Remarks on the Variation of the Environmental Temperature." Journal of Solar Energy Engineering 118, no. 2 (May 1, 1996): 81–88. http://dx.doi.org/10.1115/1.2848020.

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Energy storage is a key technology for many purposes and in particular for air conditioning plants and a successful exploitation of solar energy. Thermal storage devices are usually classified as either variable temperature (“sensible heat”) or constant temperature (“latent heat”) devices. For both models a basic question is to determine the efficiency suitably: Only exergy efficiency appears a proper way. The aim of this paper is to examine exergy efficiency in both variable and constant temperature systems. From a general statement of exergy efficiency by the present author, two types of actual definitions are proposed, depending on the fact that the exergy of the fluid leaving the thermal storage during the charge phase can be either totally lost or utilized elsewhere. In addition, specific remarks are made about the exergy of a system in a periodically varying temperature environment.

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Nayan, Kamal, Abhishek Anand, Amritanshu Shukla, Dharam Buddhi, and Atul Sharma. "Development of phase change materials for low-temperature thermal energy storage application." F1000Research 11 (November 11, 2022): 1295. http://dx.doi.org/10.12688/f1000research.127093.1.

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Background: Energy storage is very critical for reducing the mismatch between demand and supply thus offering better management capabilities. It reduces the peak energy demand and increases efficiency, security, and reliability. There is unavailability of low-cost phase change materials (PCMs) in the lower temperature range. Methods: This study discusses the creation of eutectic from capric acid and paraffin wax. A series of blending of capric acid/paraffin wax (CA/PW) were prepared, having variable weight-composition. The thermophysical properties were obtained using differential scanning calorimetry, Further, thermal cycle testing was done to understand the thermal stability and reliability of the prepared eutectics. Results: The area underneath the peak is used to calculate the latent heat of fusion, and the tangent of the steepest slope at the peak of the crest is used to calculate the melting temperature (Tm). Differential scanning calorimetry results showed the developed eutectic had an appropriate melting temperature and adequate latent heat of fusion of 29.86 °C - 30.60 °C and 154.15–198.62 kJ/kg respectively, and can be used for various thermal energy storage applications in buildings, solar absorption chillers, surgical dress/clinical bed, and photovoltaic systems. Conclusions: The accelerated thermal cycle of the same confirmed its thermal stability up to 500 heating and cooling cycles. It was discovered that variable heating and cooling speeds had no significant influence on the melting temperature and latent heat of fusion of PW/CA eutectics. Further, the economic study revealed that the created PCM is inexpensive and readily available in the Indian market.

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Jotshi, C. K., D. Y. Goswami, J. F. Klausner, and S. Malakar. "A water heater using very high-temperature storage and variable thermal contact resistance." International Journal of Energy Research 25, no. 10 (2001): 891–98. http://dx.doi.org/10.1002/er.727.

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Li, Kecen, Jie Chen, Xueqin Tian, and Yujing He. "Study on the Performance of Variable Density Multilayer Insulation in Liquid Hydrogen Temperature Region." Energies 15, no. 24 (December 7, 2022): 9267. http://dx.doi.org/10.3390/en15249267.

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The storage of hydrogen is important for the development of hydrogen energy, especially for the storage of liquid hydrogen, which has been receiving more and more attention recently. In order to study the thermal insulation performance of variable-density multilayer insulation (VDMLI) structures under different working conditions at liquid hydrogen temperatures without incorporating a composite structure, we established a heat transfer model based on a layer-by-layer calculation method. Then, we carried out numerical calculations to analyze the influence of the total number of layers, the thermal boundary temperature, and vacuums on the performance of MLI at liquid hydrogen temperatures. To investigate the optimization of variable-density configurations on the thermal insulation performance of VDMLI and to obtain accurate variable-density configurations, we proposed a variable-density configuration method based on the control variable method and the insertion by region method. The results indicate that the optimal variable-density configuration is the insertion of 4 layers of radiation shields in the low-density region, 15 layers in the medium-density region and 38 layers in the high-density region. Compared with a uniform-density structure, the heat flux is reduced by 8.6%.

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Adebiyi, G. A., B. K. Hodge, W. G. Steele, A. Jalalzadeh-Azar, and E. C. Nsofor. "Computer Simulation of a High-Temperature Thermal Energy Storage System Employing Multiple Families of Phase-Change Storage Materials." Journal of Energy Resources Technology 118, no. 2 (June 1, 1996): 102–11. http://dx.doi.org/10.1115/1.2792700.

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Previous work by one of the authors entailed modeling of a packed bed thermal energy storage system utilizing phase-change materials (PCM). A principal conclusion reached is that the use of a single family of phase-change storage material may not in fact produce a thermodynamically superior system relative to one utilizing sensible heat storage material. This paper describes the model constructed for the high-temperature thermal energy storage system utilizing multiple families of phasechange materials and presents results obtained in the exercise of the model. Other factors investigated include the effect on system performance due to the thermal mass of the containment vessel wall and variable temperature of the flue gas entering the packed bed during the storage process. The results obtained indicate efficiencies for the system utilizing the five PCM families exceeding those for the single PCM family by as much as 13 to 26 percent. It was also found that the heat transfer to the containment vessel wall could have a significant detrimental effect on system performance.

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Demchenko, Vladimir, Alina Konyk, and Vladimir Falko. "Mobile Thermal Energy Storage." NTU "KhPI" Bulletin: Power and heat engineering processes and equipment, no. 3 (December 30, 2021): 44–50. http://dx.doi.org/10.20998/2078-774x.2021.03.06.

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The article is devoted to topical issues related to the storage, accumulation and transportation of heat by stationary and mobile heat storage. Analysis of the current state of the district heating system indicates significant heat losses at all stages of providing the consumer with heat. The use of heat storage in heat supply systems leads to balancing the heat supply system, namely, the peak load is reduced; heat production schedules are optimized by accumulating excess energy and using it during emergency outages; heat losses caused by uneven operation of thermal equipment during heat generation are reduced; the need for primary energy and fuel consumption is reduced, as well as the amount of harmful emissions into the environment. The main focus is on mobile thermal batteries (M-TES). The use of M-TES makes it possible to build a completely new discrete heat supply system without the traditional pipeline transport of the heat carrier. The defining parameters affecting the efficiency of the M-TES are the reliability and convenience of the design, the efficiency and volume of the “working fluid”, the operating temperature of the MTA recharging and the distance of transportation from the heat source to the consumer. The article contains examples of the implementation of mobile heat accumulators in the world and in Ukraine, their technical and technological characteristics, scope and degree of efficiency. The technical indicators of the implemented project for the creation of a mobile heat accumulator located in a 20-foot container and intended for transportation by any available means of transport are given.

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Adinberg, R., A. Yogev, and D. Kaftori. "High temperature thermal energy storage an experimental study." Le Journal de Physique IV 09, PR3 (March 1999): Pr3–89—Pr3–94. http://dx.doi.org/10.1051/jp4:1999314.

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Mojiri, Ahmad, Nikola Grbac, Brendan Bourke, and Gary Rosengarten. "D-mannitol for medium temperature thermal energy storage." Solar Energy Materials and Solar Cells 176 (March 2018): 150–56. http://dx.doi.org/10.1016/j.solmat.2017.11.028.

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Otto, Henning, Christian Resagk, and Christian Cierpka. "Optical Measurements on Thermal Convection Processes inside Thermal Energy Storages during Stand-By Periods." Optics 1, no. 1 (April 29, 2020): 155–72. http://dx.doi.org/10.3390/opt1010011.

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Thermal energy storages (TES) are increasingly important for storing energy from renewable energy sources. TES that work with liquid storage materials are used in their most efficient way by stratifying the storage fluid by its thermal density gradient. Mixing of the stratification layers during stand-by periods decreases the thermal efficiency of the TES. Tank sidewalls, unlike the often poorly heat-conducting storage fluids, promote a heat flux from the hot to the cold layer and lead to thermal convection. In this experimental study planar particle image velocimetry (PIV) measurements and background-oriented schlieren (BOS) temperature measurements are performed in a model experiment of a TES to characterise the influence of the thermal convection on the stratification and thus the storage efficiency. The PIV results show two vertical, counter-directed wall jets that approach in the thermocline between the stratification layers. The wall jet in the hot part of the thermal stratification shows compared to the wall jet in the cold region strong fluctuations in the vertical velocity, that promote mixing of the two layers. The BOS measurements have proven that the technique is capable of measuring temperature fields in thermally stratified storage tanks. The density gradient field as an intermediate result during the evaluation of the temperature field can be used to indicate convective structures that are in good agreement to the measured velocity fields.

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Zhumabek, M. R., and M. S. Tungatarova. "Study of the efficiency of thermal energy storage in various types of short – term thermal energy storages." Bulletin of the National Engineering Academy of the Republic of Kazakhstan 83, no. 1 (March 15, 2022): 40–49. http://dx.doi.org/10.47533/2020.1606-146x.138.

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Short-term thermal energy storages allow excess heat energy to be stored for a few hours or days. Currently, coal and gas-fired thermal power plants for heating and hot water are inefficient, obsolete and have high heat losses. Therefore, the high consumption of coal and gas, which are the traditional energy sources for heating, has led to severe environmental pollution and serious environmental and health problems. In this article the heat exchange processes of short-term storage of thermal energy using phasetransition material were investigated. Paraffin was considered as a phase-transition material that can be used in short-term thermal energy storages. A numerical model of the phase change process of paraffin is shown. The basic methods of latent heat energy storage were studied. Phase change paraffin for thermal energy storage can be used in many applications such as solar energy storage, air conditioning in buildings, heating of multi-storey buildings, greenhouses and hot water supply. The paraffin wax under study has several practical values. These include the phase transition temperature of paraffin, high latent heat, fast heat transfer, high density, small volume change and thermal stability. Paraffin is one of the noncombustible materials, can be found at low cost and is environmentally friendly due to the non-toxicity of the material.

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Husainy, Avesahemad SN. "Opportunities in Latent Thermal Energy Storage by Phase Change Material for Lower Temperature Applications: A Review." Journal of Advanced Research in Mechanical Engineering and Technology 07, no. 1&2 (July 10, 2020): 1–8. http://dx.doi.org/10.24321/2454.8650.202003.

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Wang, Yudi, and Guoqiang Xu. "Numerical Simulation of Thermal Storage Performance of Different Concrete Floors." Sustainability 14, no. 19 (October 8, 2022): 12833. http://dx.doi.org/10.3390/su141912833.

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To improve the utilization rate of energy, the consumption of fossil energy must be reduced. In this study, a low-temperature radiant floor made of concrete is taken as the research object, and a two-dimensional low-temperature hot water radiant heating system with different concrete filling layers is numerically simulated using a computational fluid dynamics (CFD) software and finite element method. In this numerical model, a concrete sensible heat storage (SHTES) is adopted, while various types of concrete materials have been used to preliminarily analyze the influence of different concrete types on floor heat storage. The simulation results were further analyzed to determine the total heat storage during the heating period and the total heat storage and heat storage rate during the stable operation stage. The results demonstrate that the thermal conductivity coefficient of concrete floors had the most significant influence on the heat storage effect, with slag concrete demonstrating the most prominent heat storage effect. The total heat storage capacity of slag concrete after 7 h was 848.512 J. Overall, this study proposes a method to enhance the heat storage capacity of low-temperature radiant floors, while providing a design method for future solar energy storages and floor heat storages.

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Amin, N. A. M., Mohd Azizi Said, Azizul Mohamad, Mohd Shukry Abdul Majid, Mohd Afendi, R. Daud, Frank Bruno, and Martin Belusko. "Mathematical Modeling on Thermal Energy Storage Systems." Applied Mechanics and Materials 695 (November 2014): 553–57. http://dx.doi.org/10.4028/www.scientific.net/amm.695.553.

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Mathematical representations of the encapsulated phase change material (PCM) within thermal energy storage (TES) models are investigated. Applying the Effectiveness - Number of Transfer Unit (ɛ-NTU) method, the performances of these TES are presented in terms of the effectiveness considering the impact of different variable parameters. The mathematical formulations summarized can be used for future research work with the suggestion to maximize the heat transfer within the storage. Thus the optimisation on the configuration of the encapsulation can be done through a parametric analysis.

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Szybiak, Maciej, and Maciej Jaworski. "Design of thermal energy storage unit for Compressed Air Energy Storage system." E3S Web of Conferences 70 (2018): 01015. http://dx.doi.org/10.1051/e3sconf/20187001015.

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The aim of this paper is to present a new concept of a high-temperature thermal energy storage (TES) for the application in the compressed air energy storage (CAES) systems. The proposed storage unit combines the advantages of pressurized containers with packed beds, e.g. of rocks, with the strengths of non-pressurized systems such as those encountered in CSP plants. Designed TES unit consists of the heat exchanger located inside a high-temperature thermocline-type vessel with molten HITEC® salt used as a heat storing material. In terms of the geometry of the designed heat exchanger, a tube-in-tube helical coil type was chosen due to its higher convective heat transfer coefficients in comparison with straight tubes. To find the most suitable case, four helical coils with different dimensions (diameter, pitch) were considered. Heat transfer and pressure drop analysis for each configuration were conducted. In particular, convective and overall heat transfer coefficients as well as friction factors were computed based on the empirical correlations. To verify the obtained results, the analysis based on numerical approach has been carried out with the use of ANSYS Fluent software for the most suitable case.

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Andrássy, Z., and Z. Szánthó. "Modelling of latent thermal energy storage systems." International Review of Applied Sciences and Engineering 8, no. 1 (June 2017): 51–56. http://dx.doi.org/10.1556/1848.2017.8.1.8.

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In this paper phase change materials are presented, as effective thermal energy storage due to their great latent heat storing possibility. The main substance used for thermal energy storage purposes is water. Storing the energy with water is not that effective as with phase change materials, because the temperature of water has to change, and it worsen the heat exchange intensity. On the other hand, with phase change materials the temperature of the material does not have to change due to the latent heat storage possibilities. A buffer tank with two pipe coils filled with phase change materials is investigated with the aim to reduce the storage volume. An own thermodynamic model, a CFD simulation and an experimental system are presented. The models could be validated and the process of phase change could be examined with a life-size thermal energy storage system in the laboratory of the department. The performance of heat absorption and release of the phase change material could be calculated in the function of inlet water temperature and mass flow.

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Jurigova, Martina, and Ivan Chmúrny. "Systems of Sensible Thermal Energy Storage." Applied Mechanics and Materials 820 (January 2016): 206–11. http://dx.doi.org/10.4028/www.scientific.net/amm.820.206.

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This paper is focused on new seasonal energy storage technology. World demands for energy are increasing at present, but the resources of fuel are limited. There is a prediction, that they will become rare and more expensive in subsequent years. The technology, which can contribute to increasing the efficiency of energy consumption, is thermal energy storage. The role of such energy storage systems is to accumulate heat, balancing temperature differences and achievement the most effective use of the collected energy. Thermal energy storage plays an important role in increasing the using of renewable energy.

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Hailu, Getu, Philip Hayes, and Mark Masteller. "Long-Term Monitoring of Sensible Thermal Storage in an Extremely Cold Region." Energies 12, no. 9 (May 13, 2019): 1821. http://dx.doi.org/10.3390/en12091821.

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We present more than one-year of monitoring results from a thermal energy storage system located in a very cold place with a long winter season. The studied house is in Palmer city, Alaska (~62° N, ~149° W). The house is equipped with solar PV for electricity production and solar thermal collectors which were linked to a sensible thermal energy storage system which is underneath the house’s normally unoccupied garage and storage space. Sensors were installed in the thermal storage and solar thermal collector array to monitor system temperatures. In addition, TRNSYS was used for numerical simulation and the results were compared to experimental ones. The maximum observed garage ambient temperature was ~28 °C while the simulated maximum ambient garage temperature was found to be ~22 °C. Results indicate that seasonal solar thermal storages are viable options for reducing the cost of energy in a region with extended freezing periods. This is significant for Alaska where the cost of energy is 3–5 times the national average.

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Smusz, Robert, Paweł Kielan, and Damian Mazur. "Analysis of thermal stratified storage tank." Archives of Electrical Engineering 66, no. 3 (September 1, 2017): 631–42. http://dx.doi.org/10.1515/aee-2017-0048.

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Abstract The basic aim of the task is to compile a temperature stratification system in an accumulation tank. The range of the thesis concerns the shape and dimensions of a stratification system for an accumulation tank. Thermal stratification is a process that comprises the maintaining of temperature stratification at different levels of an accumulation tank which reduce to a minimum the process of temperature equalization. It results from the fact that the thermal stratification in a tank significantly increases the installation efficiency and improves the process of energy storing. It is connected with a thermodynamic element quality, that is the higher the temperature, the higher the energy, and, thus, the thermos-dynamic element quality. In this phenomenon, thanks to the same amount of accumulated thermal energy and average temperature, as in a fully mixed tank, the user has a higher temperature in the upper part of the tank at his disposal. It has significant importance in the case when there is a low-temperature heating medium that transfers heat to the accumulation tank. Such a situation occurs when heat is absorbed from synthetic freons used in cooling and air-conditioning systems.

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Wei, Wei, Yusong Guo, Kai Hou, Kai Yuan, Yi Song, Hongjie Jia, and Chongbo Sun. "Distributed Thermal Energy Storage Configuration of an Urban Electric and Heat Integrated Energy System Considering Medium Temperature Characteristics." Energies 14, no. 10 (May 18, 2021): 2924. http://dx.doi.org/10.3390/en14102924.

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Distributed thermal energy storage (DTES) provides specific opportunities to realize the sustainable and economic operation of urban electric heat integrated energy systems (UEHIES). However, the construction of the theory of the model and the configuration method of thermal storage for distributed application are still challenging. This paper analyzes the heat absorption and release process between the DTES internal heat storage medium and the heat network transfer medium, refines the relationship between heat transfer power and temperature characteristics, and establishes a water thermal energy storage and electric heater phase change thermal energy storage model, considering medium temperature characteristics. Combined with the temperature transmission delay characteristics of a heat network, a two-stage optimal configuration model of DTES for UEHIES is proposed. The results show that considering the temperature characteristics in the configuration method can accurately reflect the performance of DTES, enhance wind power utilization, improve the operation efficiency of energy equipment, and reduce the cost of the system.

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Wuestling, M. D., S. A. Klein, and J. A. Duffie. "Promising Control Alternatives for Solar Water Heating Systems." Journal of Solar Energy Engineering 107, no. 3 (August 1, 1985): 215–21. http://dx.doi.org/10.1115/1.3267681.

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Although the performance of solar domestic hot water (SDHW) systems has been well studied, there are several promising control alternatives that have not been thoroughly investigated. Reduced constant collector fluid flow rates, variable collector flow rates, and variable volume storage are several alternative strategies. This paper presents the results of an analytical study using the TRNSYS simulation program in which the thermal performance of SDHW systems utilizing alternative control strategies are compared while operating under realistic conditions in several different climates of the United States. The effects on system performance of time of year, collector area and quality, preheat storage tank volume and energy losses, occurrence of mixing the preheat storage tank, controller temperature deadbands, auxiliary set temperature, total daily usage, and load distribution are investigated.

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Karwacki, Jarosław, and Roman Kwidziński. "Experimental investigation of PCM thermal energy storage charge and discharge process with aperiodic (ramp) temperature inputs." E3S Web of Conferences 70 (2018): 03005. http://dx.doi.org/10.1051/e3sconf/20187003005.

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In recent years, the use of storages filled with phase-change material (PCM) is increasingly considered. Such design is characterized by a higher density of thermal energy accumulation in comparison with water storages. However, the optimal use of the PCM storages requires a recognition of its dynamic characteristics during the loading and unloading process. This paper presents research aimed at understanding and dynamic description of the heat transfer process in a shell-and-tube thermal energy storage. The experimental test stand and the measurement and control system are described. The investigated storage had a form of a cylindrical tank of 40 dm3 volume in which a coil made of pipes with an external diameter of 3.35 mm was immersed in the PCM. The total heat transfer area was 9.4 m2. A lumped parameter model was used to describe mathematically the storage thermal dynamics. The PCM used was commercially available RT15 material with the heat capacity of 150 kJ/kg in the temperature range of 10–17°C. In the investigations, aperiodic (ramp) temperature inputs were used. The storage tests were carried out for low (12 h) and high (6 h) speeds of charging and discharging. The amplitude of the input signal and the liquid temperature at the storage inlet were set to include the phase transition interval of the PCM used. The obtained test results allowed to determine the enthalpy as a function of temperature for the whole storage. The experimental results were also used to validate 0D mathematical model of the heat storage.

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Ganguly, S., and M. S. M. Kumar. "A numerical model for transient temperature distribution in an aquifer thermal energy storage system with multiple wells." Lowland Technology International 17, no. 3 (2015): 179–88. http://dx.doi.org/10.14247/lti.17.3_179.

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Kanimozhi, B., Amit Arnav, Eluri Vamsi Krishna, and R. Thamarai Kannan. "Review on Phase Change Materials in Thermal Energy Storage System." Applied Mechanics and Materials 766-767 (June 2015): 474–79. http://dx.doi.org/10.4028/www.scientific.net/amm.766-767.474.

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Phase Change Materials (PCM) plays an important role in energy conservation, which is very attractive because of its high storage density with small temperature change. In this paper an attempt made to review number of paper based on Phase Change Materials (PCM) in various field of thermal energy storage systems and its applications. The Phase Change Material is the latent heat storage material. As the source temperature raises the chemical bonds within the PCM breaks and the material changes its phase from one phase to another phase. The material begins to melt when the phase change temperature is reached. The temperature then stays constant until the melting process is finished. Thermal Energy Storage deals with the storing of energy by cooling, heating, melting, solidifying or vaporizing a material, the energy becoming available as heat when the process is reversed. Hence it is important to study about phase change materials in thermal energy storage system.Keywords: Phase change materials, Thermal energy storage system, Encapsulation, solar system, Heating and cooling of building

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Embiale, Dessie Tadele, Dawit Gudeta Gunjo, Chandraprabu Venktachalam, and Mohanram Parthiban. "Experimental investigation and exergy and energy analysis of a forced convection solar fish dryer integrated with thermal energy storage." AIMS Energy 10, no. 3 (2022): 412–33. http://dx.doi.org/10.3934/energy.2022021.

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<abstract> <p>Drying is an effective means of reducing post-harvest losses which increases the shelf life of products by reducing their moisture content to a safe storage level. An indirect mode forced convection solar dryer integrated with thermal energy storage was designed, developed and experimentally tested by drying fish. The components of the dryer are a double pass solar air heater, a paraffin wax-based shell and tube for latent heat thermal energy storage, a drying chamber and a blower. A maximum temperature of 69 ℃ was obtained at the outlet of the solar air heater, and the energy and exergy efficiencies were 25% and 1.5%, respectively. The latent heat storage reduces the fluctuations in the outlet temperature of the solar air heater and extends the drying process for two extra hours per day. The average energy and exergy efficiencies of the energy storage were 41.9% and 15.6%, respectively, whereas average energy and exergy efficiencies of the drying chamber were 35% and 52%, respectively. Moreover, 5 kg of fresh fish was effectively dried in the dryer within 21 hrs, reducing the moisture content of the fish from 75% to 12.5% by removing 3.57 kg of moisture. The specific energy consumption of the dryer was 7.3 kWh per kilogram of moisture, and the power consumed by the blower was 0.6 kWh per kilogram of moisture, which is 8.3% of the total energy consumption. The remaining 91.7% of the energy is harvested from the sun, and the overall efficiency of the drying system is 9.4%.</p> </abstract>

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Robinson, Adam. "Ultra-high temperature thermal energy storage. part 1: concepts." Journal of Energy Storage 13 (October 2017): 277–86. http://dx.doi.org/10.1016/j.est.2017.07.020.

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Ward, Patrick A., Joseph A. Teprovich, Yufei Liu, Jian He, and Ragaiy Zidan. "High temperature thermal energy storage in the CaAl2 system." Journal of Alloys and Compounds 735 (February 2018): 2611–15. http://dx.doi.org/10.1016/j.jallcom.2017.10.191.

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Kenisarin, Murat M. "High-temperature phase change materials for thermal energy storage." Renewable and Sustainable Energy Reviews 14, no. 3 (April 2010): 955–70. http://dx.doi.org/10.1016/j.rser.2009.11.011.

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Zhang, Yi, and Dong Ming Guo. "Temperature Field of Single-Well Aquifer Thermal Energy Storage in Sanhejian Coal Mine." Advanced Materials Research 415-417 (December 2011): 1028–31. http://dx.doi.org/10.4028/www.scientific.net/amr.415-417.1028.

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The technology of aquifer thermal energy storage(ATES) is an energy-saving technology which can provide a solution to energy shortages and resources expasion. The first key point of this technology is whether the aquifer can be use to store energy. In this paper, taking Sanhejian Coal Mine as an example, we choose Quaternary upper loose sandy porosity confined aquifer to bottom clayed glavel porosity confined aquifer as aquifers thermal energy storage, to discuss whether the aquifers can be used to store energy. The simulation results of aquifer temperature field show that the selected aquifers reach the goal of energy storage. And with the same irrigation flow, the lower the temperature, the more the cold water and the larger the low temperature region in aquifers thermal energy storage. With the same irrigation temperature, the lager the irrigation flow the more the cold water and the larger the low temperature region in aquifers thermal energy storage.

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Petranek, Vít, Lenka Nevřivová, Dana Zezulova, and Sergey Guziy. "Thermal Insulating Materials for Energy Storage Application." Advanced Materials Research 911 (March 2014): 30–35. http://dx.doi.org/10.4028/www.scientific.net/amr.911.30.

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In this paper various thermal energy storage mechanisms are overviewed. Furthermore, the effectiveness of three insulating materials based on alkali activated and prepared with different expanded perlite filler contents was investigated. The results showed that the developed materials could be used to insulate a thermal energy storage facility, operating in the temperature range of 650-800 °C.

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Zhang, Yi, and Dong Ming Guo. "Effect of Cold Energy Storage of Single-Well Aquifer Thermal Energy Storage in Sanhejian Coal Mine." Advanced Materials Research 430-432 (January 2012): 1433–36. http://dx.doi.org/10.4028/www.scientific.net/amr.430-432.1433.

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Effective implementation of technology of aquifer thermal energy storage (ATES) must form a "ground cold water reservoir" or "ground warm reservoir". In this paper, taking Sanhejian Coal Mine as an example, we analyze the effect of cold energy storage in single-well by analyzing the volume change of cold water body within different temperature ranges. Through the analysis of volume change of cold water body, it can prove that with the same irrigation temperature, the increase of irrigation flow makes the volume and percentage of cold water body in aquifer within different temperature ranges. And the impact on the cold water of 2-5°C is more obvious. With the same irrigation flow, both the cold water body and its percentage of 2-10°C in the condition of 2°C irrigation temperature are more than those in the condition of 5°C. The increase of irrigation flow and the decrease of irrigation temperature are beneficial to cold energy storage, and the effect of cold energy storage of the condition 3 (100m3/h irrigation flow and 2°C irrigation temperature) is the best in these four conditions.

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Lei, Hong, Chunfang Fu, Yajun Zou, Shiyan Guo, and Jichuan Huo. "A thermal energy storage composite with sensing function and its thermal conductivity and thermal effusivity enhancement." Journal of Materials Chemistry A 7, no. 12 (2019): 6720–29. http://dx.doi.org/10.1039/c8ta11753e.

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Boonsu, Rungrudee, and Sukruedee Sukchai. "Energy and Exergy Analysis of Thermal Energy Storage Prototype by Using Concrete Material in Thailand." Applied Mechanics and Materials 839 (June 2016): 14–22. http://dx.doi.org/10.4028/www.scientific.net/amm.839.14.

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The research was performed on thermal energy storage prototype in Thailand. Concrete was used as the solid media sensible heat material in order to fulfill local material utilization which is easy to handle and low cost. Saturated steam was used for heat transfer fluid. The thermal energy storage prototype was composed of pipes embedded in a concrete storage block. The embedded pipes were used for transporting and distributing the heat transfer medium while sustaining the pressure. The heat exchanger was composed of 16 pipes with an inner diameter of 12 mm and wall thickness of 7 mm. They were distributed in a square arrangement of 4 by 4 pipes with a separation of 80 mm. The storage prototype had the dimensions of 0.5 x 0.5 x 4 m. The charging temperature was maintained at 180°C with the flow rates of 0.009, 0.0012 and 0.014 kg/s whereas the inlet temperature of the discharge was maintained at 110°C. The performance evaluation of a thermal energy storage prototype was investigated in the part of charging/discharging. The experiment found that the increase or decrease in storage temperature depends on the heat transfer fluid temperature, flow rates, and initial temperature. The energy efficiency of the thermal energy storage prototype at the flow rate of 0.012 kg/s was the best because it dramatically increased and gave 41% of energy efficiency in the first 45 minutes after which it continued to rise yet only gradually. Over 180 minutes of operation time, the energy efficiency at this flow rate was 53% and the exergy efficiency was 38%.

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Moitsheki, Raseelo J. "Transient Heat Diffusion with Temperature-Dependent Conductivity and Time-Dependent Heat Transfer Coefficient." Mathematical Problems in Engineering 2008 (2008): 1–9. http://dx.doi.org/10.1155/2008/347568.

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Lie point symmetry analysis is performed for an unsteady nonlinear heat diffusion problem modeling thermal energy storage in a medium with a temperature-dependent power law thermal conductivity and subjected to a convective heat transfer to the surrounding environment at the boundary through a variable heat transfer coefficient. Large symmetry groups are admitted even for special choices of the constants appearing in the governing equation. We construct one-dimensional optimal systems for the admitted Lie algebras. Following symmetry reductions, we construct invariant solutions.

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Lahoori, Mojdeh, Sandrine Rosin-Paumier, Yves Jannot, Ahmed Boukelia, and Farimah Masrouri. "Thermal energy storage in embankments: Investigation of the thermal properties of an unsaturated compacted soil." E3S Web of Conferences 205 (2020): 07011. http://dx.doi.org/10.1051/e3sconf/202020507011.

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Thermal energy storage in compacted soils can be considered as a new economically efficient and environmentally friendly technology in geotechnical engineering. Compacted soils are usually unsaturated; therefore, reliable estimates and measurements of their thermal properties are important in the efficiency analysis of these structures. In this study, a method is used to estimate the thermal properties of an unsaturated compacted soil. Several temperature sensors were placed in a thermo-regulated metric scale container to monitor the imposed temperature variation in the range of the 20 to 50 °C. This imposed temperature variation reproduced the temperature variation in the thermal energy storages. An inverse analytical model based on a one-dimensional radial heat conduction equation is used to estimate the thermal diffusivity using the temperature variation between two temperature sensors. The volumetric heat capacity was measured using a calorimeter in the laboratory, enabling the estimation of the thermal conductivity of the compacted soil. Then, this estimated thermal conductivity was compared with the thermal conductivity values measured with two other methods (steady-state and transient-state method). The difference between them are discussed in terms of the sample heterogeneity, sample size, and measurement method.

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Al-Abdali, Akthem Mohi, and Handri Ammari. "Thermal energy storage using phase-change material in evacuated-tubes solar collector." AIMS Energy 10, no. 3 (2022): 486–505. http://dx.doi.org/10.3934/energy.2022024.

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<abstract> <p>The use of phase change materials in solar thermal collectors improves their thermal performance significantly. In this paper, a comparative study is conducted systematically between two solar receivers. The first receiver contains paraffin wax, while the other does not. The goal was to find out to which degree paraffin wax can enhance the energy storage and thermal efficiency of evacuated tubes solar collectors. Measurements of water temperature and solar radiation were recorded on a few days during August of 2021. The experimental analysis depended on two stages. The first stage had a flow rate of 7 L/hr, and the second stage had no flow rate. A flow rate of 7 L/hr gave an efficiency of 47.7% of the first receiver with phase-change material, while the second conventional receiver had an efficiency rate of 40.6%. The thermal efficiency of the first receiver during the day at which no flow rate was applied was 41.6%, while the second one had an efficiency rate of 35.2%. The study's significant results indicated that using paraffin wax in solar evacuated tube water-in-glass thermal collectors can enhance their thermal energy storage by about 8.6% and efficiency by about 7%. Moreover, the results revealed that the solar thermal collector containing paraffin wax had an annual cost of 211 USD/year. At the same time, the receiver's yearly fuel cost was 45 USD. Compared to an electrical geyser, the annual cost reached 327 USD, with an annual fuel cost equaled 269 USD. The first receiver's payback period was 5.35 years.</p> </abstract>

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Dreißigacker, Volker. "Solid Media Thermal Energy Storage System for Heating Electric Vehicles: Advanced Concept for Highest Thermal Storage Densities." Applied Sciences 10, no. 22 (November 12, 2020): 8027. http://dx.doi.org/10.3390/app10228027.

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The integration of thermal energy storage systems enables improvements in efficiency and flexibility for numerous applications in power plants and industrial processes. By transferring such technologies to the transport sector, existing potentials can be used for thermal management concepts and new ways of providing heat can be developed. For this purpose, technology developments for solid media high-temperature thermal energy storage systems are taking place for battery-electric vehicles as part of the DLR Next Generation Car (NGC) project. The idea of such concepts is to generate heat electrically, to store it efficiently and to discharge it through a bypass concept at a defined temperature level. The decisive criterion when using such solutions are high systemic storage densities which can be achieved by storing heat at a high temperature level. However, when storing high temperature heat increasing dimensions for thermal insulation are required, leading to limitations in the achievable systemic storage density. To overcome such limitations, an alternative thermal insulation concept is presented. Up to now, conventional thermal insulations are based on sheathing the storage containment with efficient thermal insulation materials, whereby the thickness results from safety restrictions with regard to the permitted maximum surface temperature. In contrast, the alternative concept enables through the integration of the external bypass into the thermal insulation systemic advantages during the charging and discharging period. During discharging, previously unused amounts of heat or heat losses within the thermal insulation can be integrated into the bypass path and the insulation thickness can be reduced during loading through active cooling. Using detailed models for both the reference and the alternative thermal insulation concept, systematic simulation studies were conducted on the relevant influencing variables and on the basis of defined specifications. The results confirm that the alternative thermal insulation concept achieves significant improvements in systemic storage densities compared to previous solutions and high potentials to overcome existing limitations.

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Gabrielsson, Erik. "Seasonal Storage of Thermal Energy—Swedish Experience." Journal of Solar Energy Engineering 110, no. 3 (August 1, 1988): 202–7. http://dx.doi.org/10.1115/1.3268258.

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Sweden reacted to the oil crises of the 1970s by initiating a comprehensive programme of research into, and development of, alternative energy sources. One of the problem areas in this connection is that of energy storage. This paper describes documented Swedish experience of seasonal thermal energy stores, concerned with such aspects as heat balances, heat losses, water sealing, stratification and temperature fields in heat stores and their surroundings. The paper concludes with mention of a number of design guidelines developed from Swedish R&D experience.

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Pagkalos, Christos, Michalis Gr Vrachopoulos, John Konstantaras, and Kostas Lymperis. "Comparing water and paraffin PCM as storage mediums for thermal energy storage applications." E3S Web of Conferences 116 (2019): 00057. http://dx.doi.org/10.1051/e3sconf/201911600057.

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A CFD analysis is performed in two different heat storage mediums, water and paraffin phase change material (PCM), in order to evaluate and compare the two mediums for use in heating thermal energy storage (HTES) applications. The two mediums use different heat storing mechanisms, namely water uses Sensible Heat Storage, and the PCM Latent heat storage. The applied computational domain represents a single tube of a heat exchanger (HE), and so it comprises of a copper tube with aluminium fins. The geometric characteristics of the domain are taken in accordance with commercially used HE’s for HTES applications [1]. The characteristics studied are the stored energy of the system, the temperature of the heat transfer fluid (HTF) in the outlet and the temperature of the storage medium. The results of the simulations showed that for the same mass of storage mediums, the PCM can store more energy than water, for the same temperature of the HTF, as expected. Also, the temperature of the medium for the sensible heat storage rises linearly with the energy stored inside it, while in the latent heat storage mechanism, the temperature of the medium rises linearly till the melting (or solidification) of it, then stays almost steady until the melting of the whole volume and then rises again until it reaches the temperature of the HTF.

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Laing, Doerte, Carsten Bahl, Thomas Bauer, Michael Fiss, Nils Breidenbach, and Matthias Hempel. "High-Temperature Solid-Media Thermal Energy Storage for Solar Thermal Power Plants." Proceedings of the IEEE 100, no. 2 (February 2012): 516–24. http://dx.doi.org/10.1109/jproc.2011.2154290.

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Gao, Liuhua, Jun Zhao, Qingsong An, Xueling Liu, and Yanping Du. "Thermal performance of medium-to-high-temperature aquifer thermal energy storage systems." Applied Thermal Engineering 146 (January 2019): 898–909. http://dx.doi.org/10.1016/j.applthermaleng.2018.09.104.

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Li, Junfeng, Wu Lu, Zhengping Luo, and Yibing Zeng. "Thermal stability of sodium nitrate microcapsules for high-temperature thermal energy storage." Solar Energy Materials and Solar Cells 171 (November 2017): 106–17. http://dx.doi.org/10.1016/j.solmat.2017.06.028.

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Herna´ndez-Guerrero, Abel, Salvador M. Aceves, Eduardo Cabrera-Ruiz, and Ricardo Romero-Me´ndez. "Effect of Cell Geometry on the Freezing and Melting Processes inside a Thermal Energy Storage Cell." Journal of Energy Resources Technology 127, no. 2 (May 18, 2005): 95–102. http://dx.doi.org/10.1115/1.1789517.

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This paper presents an analysis of the charge and discharge processes in a latent thermal energy storage cell. An individual cell is analyzed to study how its behavior affects the performance of a thermal energy storage system. The analysis considers the exchange of thermal energy between a thermal energy storage cell and a source or sink of thermal energy. Two cases are considered, (i) a process in which the phase change material melts and freezes when a constant and uniform temperature is imposed at the lower surface of the cell, and (ii) a process in which the phase change material melts and freezes when a fluid with a constant inlet temperature flows under the cell. The effect of the aspect ratio of the energy storage cell is analyzed in detail as a possible method to enhance heat transfer and improve performance of the thermal energy storage system. The results include, for different aspect ratios of the storage cell, the evolution of the solid-liquid interface, the rates of melting and solidification, the rate of energy storage and the total amount of energy storage.

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Sredenšek, Klemen, Sebastijan Seme, Bojan Štumberger, Miralem Hadžiselimović, Amor Chowdhury, and Zdravko Praunseis. "Experimental Validation of a Dynamic Photovoltaic/Thermal Collector Model in Combination with a Thermal Energy Storage Tank." Energies 14, no. 23 (December 6, 2021): 8162. http://dx.doi.org/10.3390/en14238162.

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The primary objective of this paper is to present a dynamic photovoltaic/thermal collector model in combination with a thermal energy storage tank. The added value of the proposed model is the use and integration of existing dynamic models for describing the entire photovoltaic/thermal system. The presented model was validated using measurements on the experimental system located at the Institute of Energy Technology, Faculty of Energy Technology, University of Maribor. The validation was carried out based on three different weather conditions—sunny, cloudy, and overcast. The validation results were evaluated using the normalized root mean square error and mean absolute percentage error for the temperature and output power of the photovoltaic/thermal collector and the temperature of the thermal energy storage tank. The model results concurred with the measurements, as the average mean absolute percentage error values for the temperature and output power of the photovoltaic/thermal collector and thermal energy storage tank temperature were 5.82%, 1.51%, and 7.58% respectively.

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Poupin, Lucas, Terry D. Humphries, Mark Paskevicius, and Craig E. Buckley. "A thermal energy storage prototype using sodium magnesium hydride." Sustainable Energy & Fuels 3, no. 4 (2019): 985–95. http://dx.doi.org/10.1039/c8se00596f.

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Bałon, Paweł, Bartłomiej Kiełbasa, Łukasz Kowalski, and Robert Smusz. "Thermal Performance of the Thermal Storage Energy with Phase Change Material." Acta Mechanica et Automatica 17, no. 1 (January 1, 2023): 76–84. http://dx.doi.org/10.2478/ama-2023-0009.

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Abstract Values of energy supply and demand vary within the same timeframe and are not equal. Consequently, to minimise the amount of energy wasted, there is a need to use various types of energy storing systems. Recently, one can observe a trend in which phase change materials (PCM) have gained popularity as materials that can store an excess of heat energy. In this research, the authors analysed paraffin wax (cheese wax)’s capability as a PCM energy storing material for a low temperature energy-storage device. Due to the relatively low thermal conductivity of wax, the authors also analysed open-cell ceramic Al2O3/SiC composite foams’ (in which the PCM was dispersed) influence on heat exchange process. Thermal analysis on paraffin wax was performed, determining its specific heat in liquid and solid state, latent heat (LH) of melting, melting temperature and thermal conductivity. Thermal tests were also performed on thermal energy container (with built-in PCM and ceramic foams) for transient heat transfer. Heat transfer coefficient and value of accumulated energy amount were determined.

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Merry, N., and B. Rubinsky. "Energy Storage in a Fluidized Bed." Journal of Heat Transfer 111, no. 3 (August 1, 1989): 726–30. http://dx.doi.org/10.1115/1.3250743.

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An experimental study was performed to investigate the possible use of a compound that undergoes solid-to-solid phase transformation for energy storage in a fluidized bed configuration, and to determine the heat transfer characteristics of this system. It was shown that the heat transfer coefficients from a surface immersed in the fluidized bed are a function of the bed temperature and of the temperature of the immersed surface. The heat transfer process is enhanced by the phase transformation by as much as a factor of four relative to the heat transfer in the same material without phase transformation. The experimental results suggest the possible existence of a thermal resistance between the surface immersed in the fluidized bed and the particles, which is responsible for the particular experimentally observed thermal behavior.

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Mofijur, M., Teuku Mahlia, Arridina Silitonga, Hwai Ong, Mahyar Silakhori, Muhammad Hasan, Nandy Putra, and S. M. Rahman. "Phase Change Materials (PCM) for Solar Energy Usages and Storage: An Overview." Energies 12, no. 16 (August 17, 2019): 3167. http://dx.doi.org/10.3390/en12163167.

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Solar energy is a renewable energy source that can be utilized for different applications in today’s world. The effective use of solar energy requires a storage medium that can facilitate the storage of excess energy, and then supply this stored energy when it is needed. An effective method of storing thermal energy from solar is through the use of phase change materials (PCMs). PCMs are isothermal in nature, and thus offer higher density energy storage and the ability to operate in a variable range of temperature conditions. This article provides a comprehensive review of the application of PCMs for solar energy use and storage such as for solar power generation, water heating systems, solar cookers, and solar dryers. This paper will benefit the researcher in conducting further research on solar power generation, water heating system, solar cookers, and solar dryers using PCMs for commercial development.

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Firman, I. N. G. Wardana, Sudjito Soeparman, and Nurkholis Hamidi. "Study of Thermal Energy Storage Using Oleic Acid." Applied Mechanics and Materials 695 (November 2014): 281–84. http://dx.doi.org/10.4028/www.scientific.net/amm.695.281.

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Currently, implementation of storage energy technologies is much growing. Various types of fatty acids have been used as energy storage materials. However, the use of oleic acid is required advance study. Identification of Oleic acid is conducted using FTIR test standard of ASTM E 1252-07 and the chemical composition materials are determined by GC-MS. The analysis of melting temperature and crystallize temperature are done using DSC test standard of ASTM D 3419-08. From FTIR test, it is obtained that the spectra results show the identification of oleic acid (C18H34O2) and the GC-MS test shows that the material composition has a purity concentration of 87.317%. Meanwhile, DSC test show that oleic acid could store heat energy at 6.58°C and crystallization is performed at-4.33°C.

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Koželj, Rok, Žiga Ahčin, Eva Zavrl, and Uroš Stritih. "Improved thermal energy storage for heating and cooling of buildings." E3S Web of Conferences 111 (2019): 01100. http://dx.doi.org/10.1051/e3sconf/201911101100.

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One of the great challenges in the energy sector represents retrofit of residential buildings where 3/4 of buildings in Europe are residential. To reduce energy consumption and increase the use of renewables in existing residential buildings a holistic approach of retrofit with interconnected technological system is needed. In the present paper energy toolkit based on the synergetic interaction between technologies integrated in the system for holistic retrofit of residential buildings which is under development within HEART project (HORIZON 2020) is presented. In this project step towards self-sufficient heating and cooling of building is made with an increase in on-site consumption of self-produced energy in PV from solar energy, where produced electrical energy is used also for heat pump operation. In this case thermal energy storage plays an important role for storing heat or cold for time when solar energy is not available. Improvement of sensible thermal energy storage with implemented cylindrical modules at the top of the heat storage tank and filled with phase change material is investigated experimentally. 43 litres of paraffin with phase change temperature between 27 °C and 29 °C was used in a system, what represented 15 % of total volume of heat storage tank. The results from experiment shows that thermal energy storage unit with integrated modules filled with phase change material can supply desired level of water temperature for twice as long at smaller temperature level as sensible thermal energy storage what is the consequence of higher energy density that can be stored during phase change. The advantage of phase change materials is in thermal energy storage for applications that needs narrow temperature range of supplying and storing thermal energy what is the subject matter of consideration in the case of HEART project.

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Journal articles on the topic 'Variable-Temperature Thermal Energy Storage'

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