Numerical simulation of boiling heat transfer of R32 flowing in a small diameter horizontal smooth tube

Abstract As a transitional alternative refrigerant, R32 has been used in domestic air conditioners. At the same time, the heat transfer tube size of the evaporator of domestic air conditioners develops towards small tube diameter. This paper focuses on the numerical simulation study of the boiling heat transfer characteristics of R32 flowing in a horizontal smooth tube with an inner diameter of 4 mm, and analyzes the influence of the change of tube diameter. The results show that the boiling heat transfer coefficient increases with the increase of mass flux, heat flux and saturation temperature, and decreases with the increase of tube diameter and inlet dryness. In a horizontal smooth tube with an inner diameter of 4 mm. The boiling heat transfer coefficient in the tube increased by 18.95% when the mass flux was increased from 100 kg·m-2·s-1 to 250 kg·m-2·s-1. The boiling heat transfer coefficient increased by 182.25% when the heat flux was increased from 3 kW·m-2 to 14 kW·m-2. The boiling heat transfer coefficient increased by 25% when the saturation temperature was increased from 280.15 K to 284.15 K. The boiling heat transfer coefficient increased by 19.62% when the tube diameter was decreased from 6 mm to 3 mm.