微细通道内R1234ze(E)和R134a冷凝特性的数值模拟  

Numerical simulation on condensation characteristic of R1234ze(E) and R134a in a mini-channel

作　　者：顾昕[1] 文键[1] 张星 王斯民[2] 厉彦忠[1] GU Xin;WEN Jian;ZHANG Xing;WANG Si-min;LI Yan-zhong(School of Energy and Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China;School of Chemical Engineering and Technology,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]西安交通大学能源与动力工程学院,陕西西安710049 [2]西安交通大学化学工程与技术学院,陕西西安710049

出　　处：《高校化学工程学报》2020年第1期96-103,共8页Journal of Chemical Engineering of Chinese Universities

基　　金：国家自然科学基金(51676146)

摘　　要：为了解新型环保工质R1234ze(E)微小通道内的冷凝换热及阻力特性,提出采用VOF(volume of fluid)模型对R1234ze(E)和R134a(Tsat=40℃)在水平微细圆管(Dh=1mm)内的冷凝过程进行数值模拟研究,探讨质量流量、干度以及物性对管内冷凝换热和阻力性能的影响。结果表明,R1234ze(E)和R134a的换热系数和压降都随质量流速和干度的增大而增大。相同情况下,R1234ze(E)换热系数小于R134a,但压降大于R134a。R1234ze(E)的液膜厚度平均要比R134a薄15.7%。当气液两相都为湍流,有效热导率对不同工质在水平圆管内的冷凝换热性能有重要影响。R1234ze(E)在管内的液膜分布特性整体上和R134a相似。现有的关联式对R1234ze(E)的压降都存在一定的低估,平均绝对误差都在30%左右。In order to understand condensation heat transfer and pressure drop characteristics of a new environment-friendly refrigerant R1234ze(E)in a mini-channel,the VOF(Volume of Fluid)model was adopted to investigate the condensation performance of R1234ze(E)and R134a(Tsat=40℃)inside a mini-channel(Dh=1 mm).The effects of mass flux,vapor quality and physical properties on condensation heat transfer coefficients and pressure gradients were discussed.The results indicate that both the heat transfer coefficients and pressure gradients of R1234ze(E)and R134a increase with the vapor quality and mass velocity.The condensation heat transfer coefficients of R1234ze(E)were lower than that of R134a under same conditions.However,the pressure gradients of R1234ze(E)were larger than that of R134a.The average film thickness of R1234ze(E)was on average 15.7%thinner than that of R134a.The effective thermal conductivity played an important role in local heat transfer performance of the two refrigerants.The local film distribution of R1234ze(E)was similar with that of R134a.The existing correlations seemed to underestimate the pressure gradients of R1234ze(E)with mean absolute deviation of 30%.

关 键 词：微细通道 冷凝 R1234ze(E) 换热系数 压降梯度 

分 类 号：TK124[动力工程及工程热物理—工程热物理]