Influence of Flow Rate of Thermal Fluid on Duration of Heating of SWS-1L Adsorbent in Heat Exchanger

Abstract

Adsorption heat pumps are an alternative way of heat and cold generation. Due to the high adsorption capacity and high specific energy storage capacity, the SWS-1L adsorbent can be efficient in adsorption heat pumps. The physicochemical properties of various adsorbents and kinetics of adsorption and desorption of vapors of working fluids based on them have been studied quite well, and methods have been developed to optimize the efficiency of cycles with consideration of a large number of determining parameters: properties of adsorbent, temperature, pressure, and geometric parameters of the adsorbing heat exchanger. However, there is little experimental data on the change with time in the temperature of the free surface of a layer of adsorbent granules. It is important to know how this temperature varies for accurate calculation of the heat transfer parameters. The work shows that at the beginning of heating, the surface temperature of the heat exchanger (metal) without an adsorbent increases to a quasi-stable value within 40–45 s. In the presence of the adsorbent, this time almost doubles and corresponds to 70–75 s. Increase in the thermal fluid flow from 0.65 l/min to 2.7 l/min (4.1 times) leads to a 3.8-fold decrease in the heating time of the heat exchanger with the adsorbent (also approximately 4 times). The characteristic time of thermal inertia (along the thickness of the heat exchanger wall and along the height of the adsorbent layer) without and with the adsorbent is 0.5–1 s and 4–6 s, respectively. The growth of the thermal fluid velocity leads to a significant reduction in the heating time of the heat exchanger and adsorbent and can also reduce the desorption time in a heat pump.