Numerical simulation study of boiling heat transfer of R290 flow in horizontal microtubes

Abstract R290 is considered to be an excellent alternative refrigerant for domestic air conditioners in the future. In this paper, CFD numerical simulation was used to obtain the flow field distribution of R290 in a micro-fine circular tube with an inner diameter of 2mm under a specific range of working conditions, and the effects of saturation temperature, mass flow density, heat flow density and tube type on the boiling heat transfer characteristics of R290 tube were investigated. The results show that the boiling heat transfer coefficient increases with the increase of saturation temperature, and the maximum value of the heat transfer coefficient increases by 8.1% when the saturation temperature increases from 284K to 286K. The boiling heat transfer coefficient increases with the increase of mass flow density, and the maximum value appears in the medium dryness range. The boiling heat transfer coefficient in the tube increases and then decreases when the heat flow density increases from 10 kW/m2 to 20 kW/m2 and increases faster at high heat flow density conditions. In addition, compared with the circular tube, the boiling heat transfer coefficient in the elliptical tube with an aspect ratio of 1.56 increases by 2.78% for R290 under the same flow area.