非平衡条件下氯化锰-氨的吸附/解吸特性分析

Adsorption/Desorption Non-Equilibrium Characteristics of Composite MnCl_2-NH_3 Working Pair

研究了非平衡条件下氯化锰复合吸附剂吸附氨的压力/温度曲线,并与Claperon反应平衡曲线进行了对比.结果发现,在相同的冷凝/蒸发条件下,氯化锰吸附(解吸)氨的量随着温度的变化而变化,说明非平衡吸附/解吸过程为双变量控制,而不是单变量控制.这一研究结果与理论上的Claperon曲线有较大的差别.为了验证研究结果,对吸附剂的等压吸附过程进行了测试.结果表明:吸附过程与平衡压力/温度曲线相符合;解吸过程则存在着严重的滞后现象,并且该现象主要在解吸4mol氨之后出现.考虑解吸滞后条件,计算了单级吸附制冷系统的制冷系数(COP)和单位质量吸附剂的制冷功率(SCP),结果显示,按照传统理论所得到的COP和SCP与实际测试结果的误差分别达到25%与40%,说明对于化学吸附制冷过程的理论计算需要以非平衡吸附性能测试作为基础.

This paper investigated the adsorption/desorption non-equilibrium characteristics of composite MnCl2-NH3 working pair by comparing with the Clapeyron reaction equilibrium curve.The experimental results showed that under the same condensation/evaporation conditions,for the sorption/desorption process of MnCl2-NH3 the Clapeyron curves for different sorption molar quantities were different,i.e.,the process of non-equilibrium sorption/desorption was controlled by dual variables,rather than a single variable.The results were much different from theoretical Clapeyron curves.To verify the results,the isobaric sorption process of sorbent was tested.The results showed that the adsorption process was in accord with the experimental Clapeyron curves,whereas the serious desorption hysteresis existed especially for the sorption quantity of 4mol mol-1.By considering the results of desorption hysteresis,the coefficient of performance（COP）and specific cooling power（SCP）of the working pair were analyzed.A comparison of the equilibrium theoretical and the experimental non-equilibrium analysis results showed that the error of conventional theoretical results of COP and SCP reached 25% and 40%,respectively,indicatingthat the performance analysis of chemical sorption refrigeration processes should be based on the non-equilibrium sorption performance test.