Abstract:

A finned elliptical casing evaporative condenser experimental test system was constructed, and the effects of head wind speed, inlet air wet bulb temperature, circulating cooling water temperature and flow rate on the heat and mass transfer performance of this condenser were investigated by using the control variable method.The experimental results show that as the frontal wind speed gradually increased from 2.5 m/s to 3.7 m/s, the air pressure drop outside the heat exchanger tubes increased by 6.07 times. The increase in frontal wind speed led to a rise in air pressure loss outside the tubes, but it significantly improved the heat and mass transfer performance. The external heat flux density and the external heat transfer coefficient increased by 22.3% and 25.6%, respectively, and the water film-air mass transfer coefficient outside the tubes increased by 19.1%, with the optimal frontal wind speed being 3.1 m/s. When the inlet air wet-bulb temperature increased from 9.6℃ to 11.6℃, both the external heat flux density and the external heat transfer coefficient of the heat exchanger decreased by 92.2%. As the circulating cooling water temperature rose from 17℃ to 33℃, the internal heat flux density decreased by 47.8%, and the internal heat transfer coefficient decreased by 38.1%, indicating that higher inlet air wet-bulb temperature and circulating cooling water temperature both reduce the heat transfer performance of the heat exchanger. Increasing the cooling water flow rate from 0.066 m³/h to 0.162 m³/h resulted in increases of 83.4% in internal heat flux density and 91.4% in internal heat transfer coefficient, demonstrating that increasing the cooling water flow rate can significantly enhance heat transfer performance. This study provides a reference for further exploration of the heat and mass transfer processes in evaporative condensers and their application in practical engineering.

Key words: evaporative condenser, finned elliptical cased heat exchanger, heat transfer, mass transfer, experimental validation

摘要：

搭建了翅片式椭圆套管蒸发式冷凝器实验测试系统，采用控制变量法研究了迎面风速、进口空气湿球温度、循环冷却水温度和流量对该冷凝器传热传质性能的影响规律。实验结果表明：迎面风速从2.5 m/s逐渐增至3.7 m/s，换热器管外空气压降增加了6.07倍，迎面风速的增大导致管外空气压力损失上升，但迎面风速的增加可显著提升传热传质性能，外热通量和外传热系数分别增加了22.3%和25.6%，管外水膜-空气传质系数增加了19.1%，而且最佳迎面风速为3.1 m/s。进口空气湿球温度从9.6℃增至11.6℃，换热器外热通量和外传热系数均减少了92.2%；循环冷却水温度从17℃增至33℃，内热通量减少了47.8%，内传热系数减少了38.1%，表明进口空气湿球温度和循环冷却水温度升高均会使换热器的传热性能下降。循环冷却水流量从0.066 m³/h增至0.162 m³/h，内热通量和内传热系数分别增加了83.4%和91.4%，表明增大循环冷却水流量可以显著提高传热性能。对该蒸发式冷凝器传热传质性能的实验研究可为其实际应用提供理论和实验依据。

关键词: 蒸发式冷凝器, 翅片式椭圆套管换热器, 传热, 传质, 实验验证