日光温室冷凝除湿系统用蒸发器强化传热数值分析  

Numerical analysis of enhanced heat-mass transfer in evaporator for condensing dehumidification in solar greenhouses

作　　者：胡万玲[1] 张程 唐睿 张云 管勇[1] 李建霞[1] 许凤[1] Hu Wanling;Zhang Cheng;Tang Rui;Zhang Yun;Guan Yong;Li Jianxia;Xu Feng(School of Environmental and Municipal Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China)

机构地区：[1]兰州交通大学环境与市政工程学院,兰州730070

出　　处：《农业工程学报》2020年第9期221-228,共8页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金资助项目(51868035;51866006);兰州交通大学百名青年优秀人才培养计划基金资助项目。

摘　　要：为提高日光温室冷凝除湿系统中蒸发器的综合换热性能,将三角翼型涡发生器强化传热技术引入到蒸发器中。该文针对平直肋片管翅式蒸发器和加装三角翼型涡发生器肋片管翅式蒸发器的热质传递与阻力性能,建立了这2种蒸发器的三维传热模型,运用平均努塞尔数、阻力系数、析湿量、肋片效率及强化传热因子等评价参数,对不同除湿工况下2种蒸发器的传热传质及阻力特性进行了对比分析。结果表明,涡发生器下游的空气通道两侧肋片表面凝结液主要分布于纵向涡流边界以外,边界形状分别呈条带状和椭球状;涡发生器降低凝结液尺寸和脱落直径的同时使蒸发器的析湿量平均增长了50.79%,增强了蒸发器排液能力和除湿能力;涡发生器使蒸发器肋片效率平均提高了2.00%,并将蒸发器空气侧平均努塞尔数平均提升了25.45%,强化传热因子平均提升了9.61%,但阻力系数平均增长了51.70%;在空气相对湿度高于70%的除湿工况下,蒸发器的入口空气流速推荐值取2 m/s。该研究可为日光温室冷凝除湿系统蒸发器的结构优化设计提供参考。An evaporator is serving as a core heat exchange equipment in condensing dehumidification system.Its heat exchange performance has posed a significant impact on the control effect of the wet environment in the solar greenhouse.In this study,delta winglet vortex generators(VGs)were introduced into the evaporator in order to enhance the comprehensive heat-mass transfer,and a heat-mass transfer model was established in the plain plate fin-and-tube evaporator.The maximum relative errors of the average Nusselt number and the flow resistance coefficient of the proposed model for the grid system were within 5%,and the numerical calculation method was verified by the experimental data.In this paper,three-dimensional dynamic simulation of the dehumidification process on the air side of evaporators was mainly based on VOF(Volume of Fluid)model and unsteady state calculation method.The formation and distribution features of the condensate were characterized by pressure,temperature,velocity,vorticity and liquid volume fraction field distribution on the air-middle interface,while,the heat-mass transfer and enhancement effects of evaporators were also analyzed by using the characteristic parameters and evaluation indexes under different dehumidification conditions(the inlet air velocity,uin=1-4m/s,inlet air relative humidity,RHin=50%-80%).The results showed that the average Nusselt number and the flow resistance coefficient on the air side of the plain plate fin-and-tube evaporator with VGs increased significantly as the flow velocity increased,whereas,as the relative humidity increased,the average Nusselt number on the air side increased obviously,but the increase of the flow resistance coefficient was small.In the evaporator,the VGs can remarkably improve the heat transfer,but deteriorate the flow resistance,where the average Nusselt number and the flow resistance coefficient on the air side increased by an average of 25.45%and 51.70%,respectively.Moreover,the mass transfer on the air side of the evaporator with VGs was sign

关 键 词：温室 蒸发器 冷凝除湿 三角翼型涡发生器 强化传热传质 

分 类 号：TU834.9[建筑科学—供热、供燃气、通风及空调工程]