Performance analysis of thermochemical energy storage integrated with heat pump for building applications

The aim of this study is to evaluate the performance during the adsorption and desorption process of a thermochemical energy storage (TES) system integrated with a heat-pump circuit. The chemical reactions of TES produce low-temperature heat, which is then transferred into the room or closed piping system to reduce the room temperature of a building. The low temperature will be used as alternative air-conditioning and will be eliminated or reduce the energy of using the conventional systems that consume high electricity. Furthermore, during the desorption process by using a heat pump, it will be operated during the off-peak hours which the rate of electricity much lower compared to peak hours. In this study, a numerical model was used to determine the regeneration temperature and TES performance. The numerical analysis was carried out using two different cycles; an adsorption cycle and desorption cycle. The operating temperature used in the modelling for charging is 60°C and the discharging is 50°C. In governing the equations on describing the thermal performance of TES, the basic refrigerant circuit of a vapour compression system was used for the adsorption heat pump. From the material synthesising and selection for this study, the material was chosen for this numerical modelling is vermiculite+CaCl2.The Engineering Equation Solver (EES) is used for the modelling of regeneration via heat pumps. The modelling was carried using two (2) different type of refrigerant in the heat pump which was the R134a and R1234yf. TES has a higher COP when using R134a compared to R1234yf ranges from 1.44 to 1.98 and 0.33 to 0.48 when the heating temperature is increasing. Other than that, the mass variation change the COP of TES using R134a has higher COP compared to TES using R1234yf ranges from 0.042 to 2.75 and 0.006 to 1.05. However, the desorption time has effect adverse on the COP, the COP of TES of using R134a is lower compared to TES of using R 1234yf ranges from 0.92 to 0.03 and 9.4 to 0.05.