Heat and Mass Transfer in Packed Bed Type Adsorber of Adsorption Refrigeration Cycle

对填充床型硅胶-A型蒸汽吸附脱附过程中的传热传质动态特性进行了实验和理论分析。通过实验获得了以下结果：1.测定了该吸附剂/吸附质对的吸附等温线。不同颗粒直径的填料床的动态换热行为没有差别，达到平衡所需的时间随着填料床层厚度的增加而变大。测量了填充床的有效导热系数，发现不同颗粒直径的床的有效导热系数测量值没有差异。在考虑吸附流体和颗粒固相中几种机理的物理模型的基础上，对吸附床内的传热传质进行了理论分析。取得了以下研究结果：1.目前的分析模型可以很好地预测实验中得到的硅胶/蒸汽吸附器的动态行为。流体对颗粒的传热阻力和吸附物质在颗粒中的扩散阻力对颗粒的影响都很小。固体颗粒内的热传导在吸附填充床内的传热传质动力学中起主导作用。

Experiments and theoretical analyzes were carried out on the dynamic characteristics of heat and mass transfer during adsorption and desorption processes in a packed bed type silica gel-A/steam adsorber. Following results were obtained from the experiments.1. An adsorption isotherm was determined for this adsorbent/adsorbate pair.2. There was no difference in the dynamic behavior of heat transfer for packed beds of different adsorbent particle diameter, and the time required to reach the eguilibrium state in the process became larger with the thickness of the packed bed layr.3. The effective thermal conductivity of packed bed was measured and there was found no difference in measured values for the beds of different particle diameter.Theoretical analyzes were performed for heat and mass transfer in the adsorbent bed, based on the physical model in which several mechanisms in both the adsobate fluid and particle solid phases are taken into consideration. Following results were obtained.1. The present analytical model was found to predict well the dynamic behavior of the silica gel/steam adsorber obtained in the experiments.2. Both the effects of the resistance to the heat transfer from the fluid to the particle and that to the diffusion of adsorbate in the particle were found to be very small.3. Thermal conduction in the solid particle was confirmed to play a dominant role in the dynamics of heat and mass transfer in adsorbent packed bed.