4种用于温室除湿的亲水翅片管蒸发器热湿传递性能分析

温室冬季高效除湿需求已经成为制约中国温室产业高质量发展的技术难题之一。为了提高温室用冷冻除湿系统中亲水翅片管蒸发器的热湿传递性能，该研究建立了低温高湿工况下平翅片、带涡产生器平翅片、波纹翅片、开缝翅片4种亲水翅片管蒸发器空气侧的数值传热模型，采用蒸发器的换热量Q、努塞尔特数Nu、摩擦因子f、单位翅片面积析湿量和强化传热因子JF等评价参数，对比分析了低温高湿工况下4种亲水翅片管蒸发器空气侧热湿传递性能。结果表明，与平翅片相比，带涡产生器平翅片、波纹翅片、开缝翅片空气侧的Nu、Q和f均高于平翅片，且开缝翅片的Q和f在相同条件下均最大；4种翅片的f随入口风速的增大而大幅度减小，而相对湿度对f的影响较小；单位翅片面积析湿量均随入口风速和相对湿度的增大而增大，波纹翅片的除湿能力最优；在入口风速1～4 m/s和相对湿度80%～95%条件下，波纹翅片管蒸发器的JF因子平均值最大，其热性能最优；在冬季寒冷地区低温高湿的温室中，推荐选用波纹亲水翅片管蒸发器对温室内空气进行除湿。该研究可为温室低温高湿环境下除湿系统用亲水翅片管蒸发器的设计与应用提供参考。

Heat and moisture transfer properties of four hydrophilic finned-tube evaporators for dehumidification in greenhouse

Efficient dehumidification has been one of the technical problems to restrict the high-quality development of the greenhouse industry in China. It is a high demand to dehumidify and recover the heat energy in the process of dehumidification during winter. Among them, the airside thermal and humidity transfer properties of finned-tube evaporators have had direct impacts on the performance of the entire dehumidification system in the greenhouse. In this study, the heat transfer models were established for the evaporators under both low temperatures and high relative humidity. Four hydrophilic finned-tube evaporators were taken with the plain fin, the plain fin with vortex generator, wavy fin, and slit fin. The numerical simulation was verified to compare the experimental data. The thermal and humidity transfer properties of four evaporators were assessed for the refrigeration dehumidification systems in the greenhouse using various parameters, including the heat transfer capacity, Nusselt number, friction factor, dehumidification capacity per area, and the enhanced heat-transfer factor. The results showed that average relative errors of less than 3% were achieved in the Nusselt number and friction factor of the models for the grid system. There were the higher Nusselt number, heat transfer capacity, friction factor of the air side in the plain fin with vortex generator, the wavy fin, and the slit fin, compared with the plain fin. The largest heat-transfer capacity and friction factor of the slit fin were achieved under the same inlet air velocity and relative humidity conditions. The friction factor also decreased significantly with the increase of inlet air velocity, with an average decrease of 26.06%, 24.87%, 21.10%, and 29.06%, respectively. By contrast, there was a relatively small effect of the relative humidity on the friction factor. The slit fin exhibited the highest heat transfer capacity and friction factor, whereas, the plain fin displayed the lowest under the same conditions. The other three types of fins improved the convection heat transfer on the air side of the evaporator, due to their unique structure. The dehumidification capacity was augmented with the rise in the inlet air velocity and relative humidity. The wavy fin shared the greatest average increase in the dehumidification capacity per area, with 8.68% and 7.60%, respectively, at inlet air velocity and relative humidity. The wavy fin-tube evaporator presented the highest average enhanced heat transfer factor of 1.084 and 1.041, respectively, under the conditions of inlet air velocity and relative humidity, indicating the most favorable thermal and humidity transfer properties. Hence, the wavy fin-tube evaporator was recommended for dehumidification at low temperatures and high relative humidity in the winter of cold regions, when the inlet air velocity exceeded 2 m/s and the relative humidity was over 80% in the greenhouse environment. The findings can provide a strong reference for the design and application of the hydrophilic finned-tube evaporators in the refrigeration dehumidification systems in the greenhouse.