双回路逆流干式蒸发器设计及实验验证
Design and experimental verification for double-loop countercurrent dry-expansion evaporators
摘要：
基于非对称空间传热理念，设计了一种新型双回路逆流干式蒸发器，并将其安装在空气源热泵机组上进行实验测试。理论计算和测试结果表明：制冷工况下，干式蒸发器总表面传热系数的理论计算值为1 709.4 W/（m2·K），实测值为1 938.1 W/（m2·K），后者比前者大11.8%；制热工况下，干式蒸发器总表面传热系数的理论计算值为1 834.9 W/（m2·K），实测值为2 226.4 W/（m2·K），后者比前者大17.5%。对误差原因进行了分析，结果显示：实际测试时壳程流速增大；蒸发器内换热管的污垢热阻很小。
Abstract：
Based on the asymmetric space heat transfer concept, designs a novel double-loop counter-currrent dry-expansion evaporator equipment, and installs it to an air-source heat pump unit and performs the experiment. Theoretical calculation and test results show that the calculated value of the overall surface coefficient of heat transfer is 1 709.4 W/（m2·K）, and the measured value is 1 938.1 W/（m2·K） for dry-expansion evaporator under cooling condition, the latter is 11.8% higher than the former; and that the corresponding values under heating condition are 1 834.9 W/（m2·K）and 2 226.4 W/（m2·K）respectively, the latter is 17.5% higher than the former. Analyses the error cause and concludes that the flow velocity in shell-side of the measured evaporator is increased, and the fouling resistance of heat exchanger tube in the measured evaporator is nearly zero.
Keywords:double-loop, countercurrent, self-supporting, dry-expansion evaporator, overall surface coefficient of heat transfer