Abstract: Evaporation heat transfer characteristics of R410A- oil mixture in 7 mm C-shape smooth tube are investigated and a new correlation for R410A-oil mixture in 7 mm C-shape smooth tube is developed. The experiment is carried out at evaporation temperature 5 ℃, and test quality ranges from 0.3 to 0.8, oil concentration ranges from 1% to 5%, mass flux range from 200 to 400 kg?m–2?s–1. Oil enhances the heat transfer, and the heat transfer coefficient becomes much larger with the increase of oil concentration, and the largest increase of heat transfer coef-ficient caused by oil is about 30.1% as compared to that of pure refrigerant. A new heat transfer correlation for R410A-oil mix-ture in 7 mm C-shape smooth tube is developed based on re-frigerant-oil mixture properties. It can agree with more than 90% experimental data within the deviation of ±15% and the average deviation and maximum deviation are 5.1% and 21.9% respectively.

Key words: Correlation, C-shape tube, Heat transfer, Oil, R410A