Numerical simulation of metal hydride based thermal energy storage system for concentrating solar power plants

Thermo-chemical based thermal energy storage systems are receiving much attention due to their higher energy density. Metal hydride based thermal energy storage (MHTES) system can store heat efficiently for the concentrating solar power (CSP) plants. MHTES systems are energy-efficient, compact, environmentally friendly and available over a wide operating temperature range. In this type of system, two reactors filled with different alloys are used to store the excess heat from the CSP plant. As the operation of the MHTES system is unsteady, to simulate its process efficiently, it is essential to study its transient heat and hydrogen transfer characteristics. A 2-D numerical model is solved for estimating the performance of the MHTES system. The fully implicit finite volume method (FVM) is used to solve the mathematical equations of the MHTES system. The alloy pair chosen for the MHTES system is Mg2Ni/ TiFeMn. The numerical model is validated against the data reported in the literature. The thermal energy storage coefficient is defined as the ratio of the total useful energy output of the MHTES system to total energy supplied to the MHTES system for the proposed system. For the given operating conditions of high temperatures (T-H1 = 623 K, T-H2 = 573 K, and low temperatures (T-L1 = 303 K, T-L2 = 293 K), the achieved thermal energy storage coefficient is 0.71. (C) 2021 Elsevier Ltd. All rights reserved.