scholarly journals Thermal Performance of a PCM-Based Thermal Energy Storage with Metal Foam Enhancement

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3275 ◽  
Author(s):  
Xue Chen ◽  
Xiaolei Li ◽  
Xinlin Xia ◽  
Chuang Sun ◽  
Rongqiang Liu
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Metal Foam ◽  
Storage System ◽  
Fluid Phase ◽  
Heat Transfer Fluid ◽  
Inlet Temperature ◽  
Release Process

The energy transport inside a phase change material (PCM) based thermal energy storage system using metal foam as an enhancement technique is investigated numerically. The paraffin is used as the PCM and water as the heat transfer fluid (HTF). The transient heat transfer during the charging and discharging processes is solved, based on the volume averaged conservation equations. The flow in PCM/foam and HTF/foam composites is modelled by the Forchheimer-extended Darcy equation, while the two-temperature model is employed to account for the local thermal non-equilibrium effect between the foam matrix and fluid phase. The results show that the overall performance is greatly improved by inserting metal foam in both HTF and PCM sides. A nearly 84.9% decrease in the time needed for the total process is found compared with the case of pure PCM, and 40% compared with the case of metal foam insert only in the PCM side. Foam porosity and HTF inlet temperature greatly affect the dynamic heat storage/release process.

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.

Exergy-Based Optimization of Sub- and Supercritical Thermal Energy Storage Systems

2014 ◽  
Author(s):  
Louis A. Tse ◽  
Reza Baghaei Lakeh ◽  
Richard E. Wirz ◽  
Adrienne S. Lavine
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage System ◽  
Heat Transfer Fluid ◽  
Energy And Exergy

In this work, energy and exergy analyses are applied to a thermal energy storage system employing a storage medium in the two-phase or supercritical regime. First, a numerical model is developed to investigate the transient thermodynamic and heat transfer characteristics of the storage system by coupling conservation of energy with an equation of state to model the spatial and temporal variations in fluid properties during the entire working cycle of the TES tank. Second, parametric studies are conducted to determine the impact of key variables (such as heat transfer fluid mass flow rate and maximum storage temperature) on both energy and exergy efficiencies. The optimum heat transfer fluid mass flow rate during charging must balance exergy destroyed due to heat transfer and exergy destroyed due to pressure losses, which have competing effects. Similarly, the optimum maximum storage fluid temperature is evaluated to optimize exergetic efficiency. By incorporating exergy-based optimization alongside traditional energy analyses, the results of this study evaluate the optimal values for key parameters in the design and operation of TES systems, as well as highlight opportunities to minimize thermodynamic losses.

Numerical Investigation of Combined Sensible/Latent Heat Thermal Energy Storage With Supercritical Carbon Dioxide As Heat Transfer Fluid at 650°C

2019 ◽  
Author(s):  
Kelly Osterman ◽  
Diego Guillen ◽  
D. Yogi Goswami
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Energy Storage ◽  
Supercritical Carbon Dioxide ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Heat Storage ◽  
Storage System ◽  
Heat Transfer Fluid ◽  
Dry Air

Abstract This paper numerically explores a high-temperature sensible-latent hybrid thermal energy storage system designed to store heat with output temperatures stabilized at approximately 550–600 °C for direct coupling with supercritical carbon dioxide (sCO2) power cycles operating at their design point. sCO2 and dry air at 25 MPa are used as heat transfer fluid (HTF) in a packed bed storage system that combines rocks as sensible heat storage and AlSi12 as latent heat storage. The base model using dry air at atmospheric pressure is compared to similar work done at ETH Zurich; the model is then extended for use with sCO2 to compare the performance of air and sCO2 at similar volumetric flow rates. It was found that sCO2 is capable of storing a significantly larger amount of energy (∼40 kWh) in the same time period as the air system (∼19 kWh), and can discharge that energy much quicker (1.5 hours compared to 4 hours). However, in order to achieve similar degrees of temperature stabilization, the total height of PCM had to be increased significantly, from 9 cm to 45 cm or more.

scholarly journals Experimental study of solidification of paraffin wax in solar based triple concentric tube thermal energy storage system

2018 ◽  
Vol 22 (2) ◽  
pp. 973-978 ◽  
Author(s):  
Rengarajan Ravi ◽  
Karunakaran Rajasekaran
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage System ◽  
Solidification Process ◽  
Energy Storage System ◽  
Paraffin Wax ◽  
Heat Transfer Fluid ◽  
Thermal Energy Storage System

This paper addresses an experimental investigation of a solar based thermal energy storage system to meet current energy demand especially for milk industry in Tamil Nadu, India. A solar based energy storage system has been designed to study the heat transfer characteristics of paraffin wax where it is filled in the middle tube, with cold heat transfer fluid flowing outer tube, inner tube, and both tubes at a time during solidification process in a horizontal triple concentric heat exchanger. In this study, main concentrations are temperature distributions in the energy storage materials such as paraffin wax during solidification process and total solidification time. Three heat recovery methods were used to solidify paraffin wax from the inside tube, outside tube, and both tubes methods to improve the heat transfer between heat transfer fluid and phase change materials. The experiment has been performed for different heat transfer fluid mass-flow rates and different inlet temperatures and predicted results shows that solidification time is reduced.

Computational Studies on Metal Foam and Heat Pipe Enhanced Latent Thermal Energy Storage

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
K. Nithyanandam ◽  
R. Pitchumani
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Energy Storage ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Metal Foam ◽  
Heat Pipes ◽  
High Energy ◽  
Heat Transfer Fluid ◽  
Design Parameters

Thermal energy storage is a distinguishing component of a concentrating solar power (CSP) system, which enables uninterrupted operation of plant during periods of cloudy or intermittent solar availability. Latent thermal energy storage (LTES) which utilizes phase change material (PCM) as a heat storage medium is attractive due to its high energy storage density and low capital cost. However, the low thermal conductivity of the PCM restricts its solidification rate, leading to inefficient heat transfer between the PCM and the heat transfer fluid which carries thermal energy to the power block. To address this limitation, LTES embedded with heat pipes and PCM's stored within the framework of porous metal foam that have one to two orders of magnitude higher thermal conductivity than the PCM are considered in the present study. A transient, computational analysis of the metal foam enhanced LTES system with embedded heat pipes is performed to investigate the enhancement in the thermal performance of the system for different arrangements of heat pipes and design parameters of metal foam, during both charging and discharging operation.

scholarly journals Thermodynamic Analysis of a High-Temperature Latent Heat Thermal Energy Storage System

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6634
Author(s):  
David W. MacPhee ◽  
Mustafa Erguvan
Keyword(s):  
Heat Transfer ◽  
Energy Efficiency ◽  
Energy Storage ◽  
Entropy Generation ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage System ◽  
Volume Ratio ◽  
Melting Time ◽  
Inlet Temperature

Thermal energy storage (TES) technologies are becoming vitally important due to intermittency of renewable energy sources in solar applications. Since high energy density is an important parameter in TES systems, latent heat thermal energy storage (LHTES) system is a common way to store thermal energy. Though there are a great number of experimental studies in the field of LHTES systems, utilizing computational codes can yield relatively quick analyses with relatively small expense. In this study, a numerical investigation of a LHTES system has been studied using ANSYS FLUENT. Results are validated with experiments, using hydroquinone as a phase-change material (PCM), which is external to Therminol VP-1 as a heat transfer fluid (HTF) contained in pipes. Energy efficiency and entropy generation are investigated for different tube/pipe geometries with a constant PCM volume. HTF inlet temperature and flow rate impacts on the thermodynamic efficiencies are examined including viscous dissipation effects. Highest efficiency and lowest entropy generation cases exist when when flow rates are lowest due to low viscous heating effects. A positive relation is found between energy efficiency and volume ratio while it differs for entropy generation for higher and lower velocities. Both efficiency and entropy generation decreased with decreasing HTF inlet temperature. The novelty of this study is the analysis of the effect of volume ratio on system performance and PCM melting time which ultimately proved to be the most dominant factor among those considered herein. However, as PCM solidification and melting time is of primary importance to system designers, simply minimizing entropy generation by decreasing volume ratio in this case does not lead to a practically optimal system, merely to decrease heat transfer entropy generation. Therefore, caution should be taken when applying entropy analyses to any LHTES storage system as entropy minimization methods may not be appropriate for practicality purposes.

Heat Transfer Analysis of a Low-Temperature Heat Pipe-Assisted Latent Heat Thermal Energy Storage System With Nano-Enhanced PCM

2018 ◽  
Author(s):  
Mahboobe Mahdavi ◽  
Saeed Tiari ◽  
Vivek Pawar
Keyword(s):  
Heat Transfer ◽  
Energy Storage ◽  
Low Temperature ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Storage System ◽  
Heat Pipes ◽  
Energy Storage System ◽  
Heat Transfer Fluid ◽  
Thermal Energy Storage System

In the current study, the thermal characteristics of a low-temperature latent heat thermal energy storage system are studied numerically. A cylinder container encloses a paraffin-based PCM, which is heated via a heat transfer fluid passing through a tube at the center. Heat pipes are incorporated into the PCM to enhance the heat transfer rate between the heat transfer fluid and the PCM. In addition, high thermal conductive nanoparticles are dispersed into the PCM to increase its thermal conductivity. A transient model is developed using ANSYS-FLUENT to simulate the charging process and study the impact of heat pipes and nanoparticles on the performance of the system. The effects of different parameters, such as the quantities of heat pipes as well as the nanoparticles types and volume fraction, are investigated.

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