Desiccant coated heat exchanger (DCHE), which can be adopted to construct a solar cooling system or desiccant heat pump system, can realize both sensible and latent load removal to provide comfortable supply air. Although it is difficult to avoid condensation in a practical application, the condensation condition of DCHEs is rarely studied. In this paper, a series of condensation experiments are carried out on the desiccant coated microchannel heat exchanger (DCMHE) under conditions with high temperature and high humidity ratio. First, by changing the temperature of cooling water, the unique dynamic characteristics of condensation different from non-condensing conditions are discussed, and the influence of desiccant coating is analyzed. Then, the parametric effects of inlet air velocity and fluid temperature on the mass transfer, heat transfer, and pressure drop performance of DCMHE are analyzed. The results show that the changing trend of the dynamic curve can be used as a sign to judge whether condensation exists or not. And the performance of DCMHE is still stable under continuous condensation conditions, which is not affected by the condensation water. In the dehumidification stage, the condensation dehumidification is dominant. In the aspect of parametric analysis, with the velocity of inlet air increasing from 0.5 m/s to 2.4 m/s, the average moisture removal in a cycle period of DCMHE reduces by 40%, while the dehumidification results per unit time air of DCMHE increases by 192%. The optimal inlet air velocity range is 1.5 m/s–2.4 m/s, considering the dehumidification and heat recovery efficiency synthetically. Due to the thermal resistance of desiccant coating, total cooling load, the effectiveness of heat exchanger, and NTU of DCMHE is about 31%, 27%, and 26% lower than that of MHE. And the effect of desiccant coating on heat transfer performance is comparatively small at high wind speed. The experimental results are expected to provide a reference for the system design of desiccant coated heat exchangers.

中文翻译：

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干燥剂涂层微通道换热器冷凝条件下性能实验研究


干燥剂涂层换热器（DCHE）可用于构建太阳能冷却系统或干燥剂热泵系统，可以实现显热负荷和潜热负荷的去除，从而提供舒适的送风。尽管在实际应用中很难避免凝结，但对DCHEs的凝结条件的研究却很少。本文在高温高湿比条件下，在干燥剂涂层微通道换热器（DCMHE）上进行了一系列冷凝实验。首先，通过改变冷却水温度，讨论了不同于非冷凝工况的独特的冷凝动态特性，并分析了干燥剂涂层的影响。然后，分析了入口空气速度和流体温度对DCMHE传质、传热和压降性能的参数影响。结果表明，动态曲线的变化趋势可以作为判断是否存在凝露的标志。并且在连续冷凝条件下DCMHE的性能仍然稳定，不受冷凝水的影响。在除湿阶段，以冷凝除湿为主。在参数分析方面，随着进风速度从0.5 m/s增加到2.4 m/s，DCMHE在一个循环周期内的平均除湿量减少了40%，而DCMHE单位时间空气的除湿效果增加了192%。综合考虑除湿和热回收效率，最佳入口风速范围为1.5 m/s~2.4 m/s。 由于干燥剂涂层的热阻，DCMHE 的总冷负荷、热交换器效率和 NTU 比 MHE 低约 31%、27% 和 26%。并且在高风速下干燥剂涂层对传热性能的影响相对较小。实验结果有望为干燥剂涂敷换热器的系统设计提供参考。