摘要
基于场协同强化理论,结合射流冲击的换热特点对常规毛细节流制冷系统进行优化,设计出一种新型的换热器装置。该换热器装置是将开孔毛细管内置到蒸发管中,使得制冷剂在节流后直接从毛细管沿轴向的不同孔口处冲击到蒸发管的内壁上蒸发换热,该冲击过程中由于速度场与温度梯度方向的协同性最大而具有显著的强化换热效果。首先,理论分析了毛细管进口速度(2m/s和0.5m/s)和开孔直径(1mm和0.5mm)的速度场与温度梯度方向的协同性,其次,在0MPa的回气压力下对该新型换热器装置进行性能试验,并以常规毛细节流系统作对比试验。试验结果表明,开孔试验中蒸发管表面的温度场比较稳定,而常规毛细试验中各测点由于毛细管节流的流量调节能力差而存在较大的波动。在蒸发压力和换热面积相同条件下,毛细试验的排气压力要比开孔试验高出13.6%,所以开孔试验的性能系数、制冷剂充注量比毛细试验更优;同时,毛细试验的压缩机功耗要比开孔试验高出9.1%,可见开孔试验系统的制冷效率比常规毛细试验的更高。开孔试验因为在多处射流冲击供液,并且射流冲击在冲击区中射流工质的流场和温度梯度场具有极好的协同度而能显著强化换热,使得蒸发管表面形成的温度场相对更均匀。
Based on the field synergy principle and enhancement of heat transfer characteristics of jet impingement,a new type heat ex-changer was designed. In this device,the capillary with opening holes was placed into the evaporation tube,making the refrigerant directly spray to the inner surface of the evaporation and absorb heat by evaporating,in which the heat transferring efficiency was extremely high because of the best coordination between velocity field and temperature gradient field. Theoretical analysis of the capillary tube was taken to learn the coordination between velocity field and temperature gradient field with inlet velocity( 2m / s and 0. 5m / s) and aperture( 1mm and 0. 5mm). Meanwhile experiments of the new type heat ex-changer were carried out under the evaporation pressure of 0 MPa,and compared with conventional capillary throttle system. The results shows the temperature field on the surface of the evaporation tube was more stable in the opening experiments,while there was a big fluctuation in contrast capillary experiment due to its poor ability of flow adjustment. With the same conditions of evaporation pressure and heat transfer area,the exhaust pressure in conventional capillary experiment was 13. 6% higher than that of opening experiment,so the coefficient of performance and refrigerant charge amount are better than those of conventional capillary experiment.Meanwhile compressor power consumption in conventional capillary experiment was 9. 1% higher than that of opening experiment,which verified the higher refrigerating efficiency of opening experiment. Due to the jet impingement of refrigerant and the best coordination between the flow field and temperature gradient field,the performance of heat ex-changer was dramatically improved,which made the temperature field on the surface of the evaporating tubes more uniform.
出处
《流体机械》
CSCD
北大核心
2016年第2期66-70,共5页
Fluid Machinery
基金
天津市科技支撑项目(14ZCZDNC00016)
四川省科技支撑项目(2015N20071)
天津市教委重点项目(2014ZD01)
关键词
蒸发器
内置毛细管
场协同
射流冲击
evaporator
built-in capillary
field synergy
jet impact
