Modeling of adsorption heat pump system based on experimental estimation of heat and mass transfer coefficients

摘要

This paper presents a zero-dimensional model for predicting the performance of adsorption heat pumps. In particular, the overall heat and mass transfer coefficients at the adsorbers are experimentally estimated. Two materials are used as adsorbents: A-type silica gel, and a natural mesoporous material termed Wakkanai siliceous shale (WSS) impregnated with 20 wt% LiCl. Corrugated fin-type heat exchangers are filled with each adsorbent at different filling densities: 223 and 305 g/L for A-type silica gel, and 233 and 329 g/L for the WSS + LiCl 20 wt %. Experiments performed to estimate the overall mass transfer coefficient are based on the large pressure jump method and are conducted at various adsorbent temperatures in the range of 30-60 degrees C. Furthermore, the overall heat transfer coefficients of the adsorbers are experimentally estimated when the inlet water temperature changes from 80 to 30 degrees C to elucidate the actual working condition of adsorption heat-pump systems. Finally, according to the adsorption time, the cooling capacity, specific cooling power (SCP), and coefficient of performance (COP) are analyzed via a dynamic model. The results indicate that the COP of the heat exchanger using the WSS composite material are improved by 6-17% compared with the heat exchanger using the A-type silica gel.