Numerical study on the dynamic performance of combined sensible-latent heat packed-bed thermocline tank

2021 ◽  
pp. 1-36
Author(s):  
Elsaeed Elsihy ◽  
Chao Xu ◽  
Xiaoze Du
Keyword(s):  
Energy Storage ◽  
Phase Change Materials ◽  
Volume Fraction ◽  
Numerical Study ◽  
Dispersion Model ◽  
Dynamic Performance ◽  
Packed Bed ◽  
Water Tank ◽  
Total Utilization ◽  
Utilization Ratio

Abstract Thermal energy storage (TES) using thermocline technology with phase change materials (PCMs) is a promising technique for peak shaving operation in cogeneration units. One of the disadvantages of this connotation is the use of the highly-cost PCM capsules in a water tank. To circumvent this issue, a new thermocline tank connotation is proposed. The tank is packed with a mixture of solid filler pills and PCMs capsules, forming a multi-layer packed-bed system. A transient concentric-dispersion model is developed to assess the dynamic performance of a solid-PCM multi-layer packed-bed (SPMLPB) tank. The influences of the PCMs volume fraction (VF) and the charge and discharge dimensionless cut-off temperatures criterion on the dynamic performance have been investigated. The results show that the VF of PCMs influences the system's behavior, both in terms of energy storage and release. As the PCMs volume fraction increases from 10% to 40%, the amount of energy storage, energy release, and latent utilization ratio increased by 82.65%, 73.94%, and 55%, respectively, while the exergy overall efficiency falls by 6.3%. Besides, increasing both the charge and discharge cut-off temperatures (ST*ch/ST*dish) enhances the total utilization ratio and energy recovered. As ST*ch increases from 0.27 to 0.7, total utilization ratio and energy recovered increased by 63.63% and 28.67% respectively by maintains ST*dish = 0.26.

scholarly journals A Comparative Study on the Performance of Single and Multi-Layer Encapsulated Phase Change Material Packed-Bed Thermocline Tanks

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2175
Author(s):  
Huiqian Guo ◽  
ELSaeed Saad ELSihy ◽  
Zhirong Liao ◽  
Xiaoze Du
Keyword(s):  
Volume Fraction ◽  
Numerical Study ◽  
Dispersion Model ◽  
Dynamic Performance ◽  
Storage Period ◽  
Packed Bed ◽  
Heat Transfer Fluid ◽  
Two Phase ◽  
Stefan Number ◽  
Utilization Ratio

This paper presents a numerical study that aims at investigating the effects of different parameters on the dynamic performance of single and multi-layer encapsulated phase material (PCM) thermocline tanks. A transient, one-dimensional, two-phase, concentric-dispersion model is formulated to evaluate such performance. Encapsulated paraffin waxes having different melting-points are used as PCMs, with water as heat transfer fluid. Comprehensive comparisons between single-PCM and multiple-PCMs systems are numerically analyzed first. Second, the effects of the PCM volume fraction (VF) and the inverse Stefan number have been discussed. The results show that among the various cases the single-PCM70 system has the highest performance in terms of charging and discharging efficiency, followed by a multiple-PCMs system with average performance. Compared with the PCM40 case, the PCM70 case has a 29% increase in the output energy from the system. The VF of PCMs influences the system output, both in terms of energy storage and release, the heat storage period and the total energy stored increased by 4.5%, when the VF of the PCM70 increases from 33.33% to 50%, respectively. Furthermore, it increases the system’s overall efficiency and total utilization ratio by 13.7% and 25%, respectively, when compared to the arrangement in which the PCM40 occupies 50% of the total bed height. The effect of the inverse Stefan number has a significant impact on the system’s utilization ratio. Compared with all other 3-PCM systems, the scenario with the lowest inverse Stefan number in the middle PCM has the highest charging and discharging efficiencies of 83.9% and 80.8%, respectively. The findings may be beneficial for the design and optimization of packed-bed tanks.

Analysis of Thermal Energy Storage to a Combined Heat and Power Plant

2021 ◽  
Vol 9 (9) ◽  
pp. 1313-1320
Author(s):  
Shahim Nisar
Keyword(s):  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Energy Demand ◽  
Power Plants ◽  
Heat Storage ◽  
Packed Bed ◽  
Water Tank ◽  
Latent Heat Storage ◽  
Storage Methods

Abstract: Thermal energy storage (TES) is a technology that stocks thermal energy by heating or cooling a storage medium so that the stored energy can be used at a later time for heating and cooling applications and power generation. TES systems are used particularly in buildings and in industrial processes. This paper is focused on TES technologies that provide a way of valorizing solar heat and reducing the energy demand of buildings. The principles of several energy storage methods and calculation of storage capacities are described. Sensible heat storage technologies, including water tank, underground and packed-bed storage methods, are briefly reviewed. Additionally, latent-heat storage systems associated with phase-change materials for use in solar heating/cooling of buildings, solar water heating, heat-pump systems, and concentrating solar power plants as well as thermo-chemical storage are discussed. Finally, cool thermal energy storage is also briefly reviewed and outstanding information on the performance and costs of TES systems are included.

Analysis of Flow Through Packed Bed of Spheres Containing Phase Change Materials for Thermal Energy Storage Applications

2019 ◽  
Author(s):  
Vinit V. Prabhu ◽  
Ethan Languri ◽  
Kashif Nawaz
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Response Time ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Response Rate ◽  
Packed Bed ◽  
Hot Water

Abstract The research on thermal energy storage (TES) systems have received a lot of attention in recent decades for sustainable use of thermal energy in various industrial and residential applications. The existing challenge in designing the TES is the response time of charging and discharging cycles that keeps these systems away from wide utilization in industries. Literature data show that beside the low thermal conductivity of most phase change materials (PCMs) as active media in TES systems, the poor flow distribution may be another factor affecting the response rate. This study aims to considerably reduce the response time by packing the PCMs in a bed of spheres made of high thermal conductivity material. The response rate during the charging cycle is studied numerically by passing hot water at 70 °C over the packed bed of spheres. The numerical analysis is performed using ANSYS Fluent 19. The PCM used in this study is a paraffin and has a melting point of 48 °C. The response rate of the system is studied and it is compared to other similar systems mentioned in literature. The amount of energy storage is also studied by changing the flow rate of water.

Numerical Study of Thermochemical Storage Using Ca(OH)2/CaO: High Temperature Applications

2016 ◽  
Author(s):  
Qasim A. Ranjha ◽  
Nasser Vahedi ◽  
Alparslan Oztekin
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Numerical Study ◽  
Storage System ◽  
Packed Bed ◽  
Heat Transfer Fluid ◽  
Operational Parameters ◽  
Storage And Retrieval

Thermal energy storage by reversible gas-solid reaction has been selected as a thermochemical energy storage system. Simulations are conducted to investigate the dehydration of Ca(OH)2 and the hydration of CaO for thermal energy storage and retrieval, respectively. The rectangular packed bed is heated indirectly by air used as a heat transfer fluid (HTF) while the steam is transferred through the upper side of the bed. Transient mass transport and heat transfer equations coupled with chemical kinetics equations for a two dimensional geometry have been solved using finite element method. Numerical results have been validated by comparing against results of previous measurements and simulations. The effect of geometrical and operational parameters including the material properties on overall storage and retrieval process has been investigated. The co-current and counter-current flow arrangements for steam and heat transfer fluid have been considered.

scholarly journals Combined Solar Thermochemical Solid/Gas Energy Storage Process for Domestic Thermal Applications: Analysis of Global Performance

2019 ◽  
Vol 9 (9) ◽  
pp. 1946 ◽  
Author(s):  
Oleksandr Skrylnyk ◽  
Emilie Courbon ◽  
Nicolas Heymans ◽  
Marc Frère
Keyword(s):  
Energy Storage ◽  
Fixed Bed ◽  
Packed Bed ◽  
Pilot Scale ◽  
Hot Water ◽  
Water Tank ◽  
Atmospheric Conditions ◽  
Storage Process ◽  
Moving Bed ◽  
Global Performance

Thermal energy used below 100 °C for space heating/cooling and hot water preparation is responsible for a big amount of greenhouse gas emissions in the residential sector. The conjecture of thermal solar and thermochemical solid/gas energy storage processes renders the heat generation to become ecologically clean technology. However, until present, few pilot scale installations were developed and tested. The present work is devoted to the experimental study of global performance of a pilot scale thermochemical energy storage prototype. Two working modes, namely fixed packed bed and moving bed, were tested using 2.2 kg and 5.5 kg of composite material (silica gel impregnated with calcium chloride) under indoor atmospheric conditions. The global experimental efficiency of a 49l water tank charging process during 75 min was found as high as 0.8–0.85. The energy storage density reached in the fixed bed mode by the material was 158 kWh/m3, while in the moving bed mode it was 2.5 times lower. The reasons for such a difference are discussed in depth in the text.

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