基于分布参数模型的满液式蒸发器性能模拟

基于流动沸腾换热的Chen氏加和模型，建立了满液式蒸发器分布参数的热力计算模型．采用分相流动模型计算制冷剂横掠管束的两相压降，考虑了压降对制冷剂饱和温度的影响；对于流程上下布置的满液式蒸发器，模型计算了制冷剂流量沿轴向的分布，改进了前人忽略制冷剂流量轴向分布对蒸发器性能的影响．应用该模型对一水平布置、2流程、采用强化管的满液式蒸发器进行了性能计算，热负荷的计算值与试验值吻合良好．同时，研究了不同管型、不同流程布置对满液式蒸发器性能的影响．

Prediction of the Performance of Flooded Refrigerant Evaporators Based on a Distributed Parameter Model

Based on the Chen two-phase forced-convection boiling model, a theoretical model with distribution parameters was developed for predicting the performance of flooded refrigerant evaporators (FRE). With this model, the effect of refrigerant pressure drop across tube rows on the refrigerant local saturation temperature is accounted. The pressure drop is calculated using the separated flow model. The Chen model is used to predict the boiling heat transfer coefficient. For FRE with bottom-to-top pass arrangement, the model improves the previous Webb's method, and the effect of no uniform distribution of refrigerant flow along the tube on the performance is accounted. An incremental, iteration calculation procedure is outlined. The model was applied to predict the performance of a commercial FRE with side-to-side water pass arrangement, and the effects of different tubes and pass arrangements on evaporator performance were analyzed. The predicted total heat transfer rate of the commercial FRE agrees well with the experimental data.