扩散吸收式制冷系统中板式换热器综合传热性能分析

摘要

在一种太阳能驱动、采用喷雾吸收器并以板式换热器作为主要换热部件的LiNO3-NH3-He三工质扩散吸收式制冷系统中，根据试验测得的运行参数，以溶液的p-t-x西方程及物性方程、传热基础理论等为依据，提出了计算溶液换热器中溶液流量的方法，并利用综合传热系数k、传热单元数N_TU与换热器效率s研究了板式换热器作为LiN03-NH3-He扩散吸收式制冷系统发生器、冷凝器、溶液热交换器、溶液冷却器时的换热性能．试验与分析表明，板式换热器的换热面积及其内部流道中的流量（流速）对其综合传热性能具有较大影响；在介质流量一定时，板式换热器不宜考虑过大的面积预留量；板式溶液换热器内部流道宜采用多流程布置形式以强化传热、提高换热效率．%A LiNO3-NH3-He diffusion-absorption refrigeration system driven by solar energy is introduced, in which a spray absorber is used to enhance the heat and mass transfer, and plate heat exchangers (PHEs) used as generator, condenser, solution heat exchanger (SHE) and solution cooler, respectively. Besides, solution flow rates in the system are evaluated based on p-t-x and physical property equations of LiNO3-NH3 solution, principles of heat transfer, and parameters such as pressure, temperatures and flow rates. Heat transfer performances are also investigated according to the overall heat transfer coefficient k, number of heat transfer units NTU and heat exchanger efficiency ε. Experiments and analysis show that, in LiNO3-NH3-He diffusion-absorption refrigeration system, heat transfer area and solution flow rates of PHEs affect the overall heat transfer performance of the PHEs. Therefore, extra size on PHE is not recommended if the solution flow rate is kept constant, and inner passageways of PHEs should adopt multi-pass to enhance heat transfer.