椭圆形套管-管翅式蒸发式冷凝器传热性能实验研究

本文搭建了蒸发式冷凝器性能测试系统，采用控制变量法实验研究了迎面风速、喷淋密度、湿球温度、循环水温度、冷却水流量各参数变化对椭圆形套管-管翅式蒸发式冷凝器传热性能的影响。实验结果表明：该冷凝器实验系统的最佳迎面风速和喷淋密度分别为3.1 m/s和0.005 6 kg/(m·s),冷凝器管外空气压降随迎面风速的增大而迅速增加；随着空气湿球温度升高，冷凝器外传热过程的热流密度(即外热流密度)降低67.5%,而内传热过程的热流密度(即内热流密度)增大47.5%,依靠内传热过程的增强，冷凝器性能良好；随着循环水温度升高，冷凝器的内热流密度降低率高达64.6%,传热性能急剧下降；随着冷却水流量增大，冷凝器的内热流密度大幅提高2.92倍，总热流密度增大21.1%,传热性能显著增强；该冷凝器在低湿球温度、低循环水温度、大冷却水流量的工况下传热性能较优。

Experimental Study on Heat Transfer Performance of Annular Elliptic Finned Tube Evaporative Condenser

A performance test system for an evaporative condenser was developed in this study. The effects of different parameters on the heat transfer performance of an annular elliptic finned tube evaporative condenser were studied using a control variable method, including the face velocity, spray density, wet-bulb temperature, circulating water temperature, and flow rate of the cooling water. The experimental results showed that the optimal face velocity and spray density of the condenser was 3.1 m/s and 0.0056 kg/(m/s), respectively. The air pressure drop increased rapidly with an increase in the face velocity. With an increase in the wet-bulb temperature, the heat flux of the external heat transfer (that is, external heat flux) decreased by 67.5%, while that of the internal heat transfer (that is, internal heat flux) increased by 47.5%. The performance of the condenser was good because the internal heat-transfer process was enhanced. With an increase in the circulating water temperature, the internal heat flux of the condenser decreased by 64.6%, while the heat-transfer performance of the condenser decreased sharply. With an increase in the cooling water flow rate, the internal heat flux of the condenser increased greatly by 2.92 times, while the total heat flux increased by 21.1%. Consequently, the heat-transfer performance of the condenser was enhanced considerably. The condenser exhibited excellent heat transfer performance at low wet-bulb temperatures, low circulating water temperatures, and large cooling water flow rates.