Two-phase heat transfer coefficients of three HFC refrigerants inside a horizontal smooth tube, Part I: Evaporation

This paper presents experimental heat transfer results obtained during the evaporation of Isceon 59, R407C and R404A in a horizontal tube. The results have been compared with existing correlations which characterize the evaporative heat transfer coefficient to assess the validity of these models for refrigerant mixtures. The results compared well with the correlations over a 0.2 to 0.8 vapour quality range. These correlations, however, did not accurately predict the results obtained during the dry-out at high vapour quality. A model, developed by (Kattan N., Thome J.R., Favrat D., 1998. Flow boiling in horizontal tubes: part 1 - development of a diabatic two-phase flow pattern map. Journal of heat transfer, transactions of ASME, Vol. 120, pp. 140-147; Kattan N., Thome J.R., Favrat D., 1998. Flow boiling in horizontal tubes: part 2 - new heat transfer data for five refrigerants. Journal of Heat Transfer, Transactions of ASME, Vol. 120, pp. 148-155; Kattan N., Thome J.R., Favrat D., 1998. Flow boiling in horizontal tubes: part 3 - development of a new heat transfer model based on flow pattern. Journal of Heat Transfer, Transactions of ASME, Vol. 120, pp. 156-165), was found to express the local variations in heat transfer during the whole evaporation process. This model was modified to fit the three new refrigerants. The modified Kattan model offers a good prediction of the heat transfer results, with a standard deviation of 6.1%.