CO_2/润滑油混合物在水平管内流动沸腾换热的试验研究  

Experimental Study on Heat Transfer Characteristics of CO_2/oil Mixtures Flow Boiling Inside Horizontal Tubes

作　　者：杨俊兰[1] 赵丽娜[1] 

机构地区：[1]天津城建大学,天津300384

出　　处：《流体机械》2015年第11期1-5,15,共6页Fluid Machinery

基　　金：国家自然科学基金项目(E060102);天津市科委应用基础及前沿技术研究计划项目(10JCYBJC08300)

摘　　要：为了测试润滑油对CO2流动沸腾换热特性的影响，以指导CO2换热器的设计，对CO2／润滑油混合物在水平管内的流动沸腾换热系数进行了试验研究，试验工况质量流量为2．74～5．61kg／h，热流密度为3．2～5kW／m^2，测试段入口干度为x=0．2～0．5，蒸发温度在-4—8℃之间，选择PAG作为润滑油，浓度为0～6％。试验结果表明，润滑油浓度越大，CO2的局部换热系数越小；润滑油浓度较低时（〈3％），换热系数下降较大，再增大含油量，换热系数下降的趋势减缓。增大蒸发温度可以延迟干涸的发生，相反地，大的热流密度和质量流量可以使管内提前出现干涸。CO2／润滑油混合物的换热系数随蒸发温度的升高而增大，随热流密度和质量流量的增大而减小。To test the boiling heat transfer characteristics of CO2/lubricant mixtures, guiding the design of the CO2 heat exchanger, the heat transfer coefficients of COs/lubricant mixtures were investigated in a horizontal tube. The experiments were conducted by varying the mass flux of CO2 from 2.74 to 5.61 kg/h, heat flux from 3.2 to 5kW/m^2 and saturation temperatures from-4 to 8℃. PAG was selected as the lubricant, whose concentration was altered from 0 to 6%. The results show that larger oil concentration degrades the heat transfer coefficient. The beat transfer coefficient decreased largely at low oil concentration （ 〈 3% ）, then with the increasing of the oil, h decreased slowly. Higher evaporation temperature results in increasing the critical mass quality, while higher heat flux and mass flux make the dry-out occur in advance. Heat transfer coefficient increases versus the rise of the evaporation temperature. Conversely, larger heat flux and mass flux will weaken the heat transfer.

关 键 词：CO2/润滑油混合物 沸腾换热 PAG 

分 类 号：TH137.8[机械工程—机械制造及自动化] TK124[动力工程及工程热物理—工程热物理]