混合制冷剂R32/R290在水平三维微肋管内沸腾换热研究  

Numerical simulation of boiling heat transfer for mixed refrigerant R32/R290 in a horizontal 3D micro-fin tube

作　　者：张茜茜 张莹[1] 张道旭 熊子悠 齐鑫 Zhang Qianqian;Zhang Ying;Zhang Daoxv;Xiong Ziyou;Qi Xin(School of Mechanical and Electrical Engineer,Nanchang University,Nanchang 330031,China)

机构地区：[1]南昌大学机电工程学院,南昌330031

出　　处：《低温工程》2020年第6期9-17,43,共10页Cryogenics

基　　金：国家自然科学基金(11562011)。

摘　　要：利用计算流体力学和数值传热学方法,分别对500 mm水平微肋管和光滑管中的新型混合制冷剂R32/R290(68:32)开展三维数值模拟和理论分析。仿真模拟采用结构化网格,分析了质量流量、饱和温度、热流密度以及干度对平均沸腾传热系数的影响。结果表明,当有临界干度出现时,两种管型的沸腾传热系数均会出现先增大后减小的趋势。微肋管蒸干现象出现的节点具有延迟性,且螺旋微肋管能有效强化沸腾换热。低干度区域,分别增加质量流量、饱和温度、热流密度都能导致沸腾传热系数增长。在不同工况下,临界干度出现的时间节点顺序不同。对距入口不同位置截面的气液两相变化规律进行分析,各个距离截面中气相占比皆由下至上逐渐增加,不同截面气相体积分数随着距离的增加而变大。Using computational fluid dynamics and numerical heat transfer methods,three-dimensional numerical simulation and theoretical analysis were carried out on the new mixed working fluid R32/R290(68:32)in 500 mm horizontal micro-fin tube and smooth tube,respectively.The simulation used a structured grid to analyze the influence of mass flow,saturation temperature,heat flux and dryness on the average boiling heat transfer coefficient.The results show that when there is a critical dryness,the boiling heat transfer coefficients of the two types of tube will first increase and then decrease.The evaporation-dryness node of the micro-fin tube is delayed,and the spiral micro-fin tube can effectively enhance the boiling heat transfer.In the low dryness area,increasing the mass flow rate,saturation temperature,and heat flux density respectively can lead to the increase of boiling heat transfer coefficient.Under different working conditions,the sequence of time nodes of critical dryness appearing is different.The vapor-liquid phases change law of the cross-sections at different positions from the inlet is analyzed.The proportion of vapor in the cross-sections gradually increases from bottom to top.The volume fraction of vapor in different cross-sections increases with the increase of distance.

关 键 词：制冷剂替代 R32/R290 沸腾换热 强化换热 微肋管 

分 类 号：TB612[一般工业技术—制冷工程]