CO_2跨临界水水热泵气体冷却器研究

STUDY ON GAS COOLER OF CO_2 TRANSCRITICALCYCLE WATER SOURCE HEAT PUMP

为提高 CO_2跨临界循环水一水热泵的效率,对气体冷却器进行了研究。对原有管壳式气体冷却器建立了模型并计算了该气体冷却器沿管长的温度分布。对该气体冷却器进行了实验研究,并改变结构参数以提高气体冷却器的换热效率。计算结果显示 CO_2侧的换热系数沿管路存在峰值,但要低于水侧的换热系数,主要原因是流量小。增加换热管长,并减小管数,有利于管内换热系数的提高,而且压力降在可接受的范围。通过实验与计算值的对比,CO_2出口温度计算偏差小于9%,水温出口温度计算偏差小于5.3%。

The gas cooler was studied to improvement of CO2 transcritical cycle water source heat pump. The model of the primary shell-tube gas cooler was set up, and the temperature distribution of the gas cooler along the tube was calculated. The experiments were conducted to test the performance of the gas cooler. The structure parameters were verified to im- prove the efficiency of the gas cooler. The calculated results show that there exists a maximum transfer coefficient of CO2 side along the tube, but the hear transfer coefficient of CO2 side is lower than that of water side. The main reason is low mass flow rate of CO2 in the tube. Enlarging the tube length and reducing the tube number will help to increase the heat transfer coefficient of CO2, and the raising pressure drop is still in acceptable range. The outlet temperature error of CO2 is within 9 % and that of water is less than 5.3 % by comparing calculated results with experimental data.