Experimental Investigation on Flow Boiling Heat Transfer of R141b in Circular Micro-Channel Heat Sinks

In order to intensify heat transfer and solve the problem of high heat flux and heat dissipation inside the equipment, the boiling heat transfer characteristics of R141b in horizontal micro-channels with different diameters (D=0.5mm and 1.0mm) were studied experimentally. The effects of heat flux (q=2.0kW/m2~47.6kW/m2), vapor quality (x=0~0.6) and mass flow rate (G=111.11kg/(m2∙s)~333.33kg/(m2∙s)) on the average heat transfer coefficient h were analyzed, and the dominant factors affecting boiling heat transfer were explored under different conditions. The experimental study showed that the average heat transfer coefficient h decreased with the increase of heat flux q in significantly different rate according to different range. The effects of mass flow rate G on the average heat transfer coefficient h are obvious when heat flux q=2kW/m2~5kW/m2, while when the heat flux is high, the mass flow rate G has little effect on the heat transfer. At different mass flow rate (G=111.11kg/(m2∙s)~333.33kg/(m2∙s)) when the vapor quality x>0.3, the average heat transfer coefficient h decreased with increasing vapor quality x. Micro-channel heat exchangers should be well-designed to insure R141b working under the initial boiling stage to achieve better heat exchange effect, and certain measures should be taken to prevent the heat deterioration caused by excessive dryness. © 2019, Editorial Department of Journal of Propulsion Technology. All right reserved.