余热制冷吸附床的一个新传热传质模型

NEW INTRA - ADSORBENT HEAT/MASS TRANSFER MODEL FOR WASTE HEAT ADSORPTION COOLING

在既考虑吸附剂颗粒内部的传质阻力,又考虑吸附剂颗粒之间的外部传质阻力的前提下,建立了余热吸附制冷系统中吸附床的三维非平衡传热传质数学模型,它包括加热/冷却流体传热模型、换热管传热模型、肋片传热模型、吸附剂颗粒床传热传质模型4部分;通过对模型的数值求解,获得了吸附床内部的温度演变曲线和性能指标,与实验结果基本吻合。

Adsorption cooling attracts large attention because it uses waste heat, non - CFC refrigerants, and has no moving parts. The traditional heat and mass transfer model for the adsorbent bed does not take into account the internal mass transfer resistance inside an adsorbent particle. Therefore, the mass transfer mechanism in the bed can not be expressed accurately. In this work, the mathematical model for the heat and mass transfers in the adsorbent of a waste heat adsorption cooling system is developed , by taking into account both the internal and the external resistance. The model includes four parts: heat transfers in heating/cooling fluids, heat transfers in the metal tube, heat transfers in the fins, and heat and mass transfers in the adsorbent. The model for the heat and mass transfers in the adsorbent is a three-dimensional non - equilibrium model that takes into account both the internal and the external mass transfer resistance in the adsorbent. In the analysis, the Darcy' s law is used to express the external mass transfer, while an empirical adsorption rate equation is used to analyze the internal mass diffusion . The model is solved with QUDS (quadratic upstream differencing scheme) and ADI (alternating direction implicit) methods, In the end, an experiment is done to validate the model.