CO_2内螺旋管式气体冷却器换热特性仿真研究

Simulation study of heat transfer characteristics of gas cooler based on internal spiral tube and CO_2

建立了一种应用于CO_2热泵热水机的内螺旋管式气体冷却器(逆流型)的换热特性稳态仿真模型,且与实验数据吻合较好。在仿真模型基础上,分析气体冷却器内部流体温度沿管长分布情况,研究结构参数和水侧进口温度对气体冷却器换热性能的影响,研究结果表明:由于CO_2侧出口温度不会低于水侧进口温度,因此换热量受水侧进口温度限制,当气体冷却器换热面积增加到一定程度时,换热量增加幅度放缓并逐渐接近其上限值;随着水侧进口温度的增加,水侧与CO_2侧的对数平均温差和换热量降低,水侧出口温度增加幅度越来越小。

The steady heat transfer simulation of a gas cooler （counter -flow） used in heat pump water heater and based on internal spiral tube and CO2was established. The model agreed well with experimental dada. On the basis of the simulation mod- el, temperature distribution of internal fluid along tube length was showed by the model. Under the certain condition of operating parameters, the influence of structure parameters and water temperature at inlet on the heat transfer performance of gas cooler was analyzed by simulation. The study results show that CO2 temperature at outlet is not lower than water temperature at inlet, heating capacity is restricted by water temperature at inlet. When heat transfer area of gas cooler increases to a certain degree,the amplification of beating capacity slows down and approaches gradually to upper limit; when water temperature at inlet increases, logarithmic mean temperature difference between water and CO2 and heating capacity decrease,the amplification of water temperature at outlet becomes small.