Substantial efforts have been made to develop low global warming potential (GWP) refrigerants in the last decade. Many studies indicate that R1234yf has similar thermodynamic properties to R134a but much lower GWP value, suggesting the opportunity of utilizing R1234yf as a substitute of R134a due to its advantages of a very low 100-year global warming potential value of 4, zero ozone depletion potential and excellent life cycle climate performance. Nevertheless, very limited studies have been conducted in the past years related to the flow condensation heat transfer of this refrigerant. The purpose of this study is to probe the condensation heat transfer and pressure drop characteristics of R1234yf in a horizontal circular minitube with an inner diameter of 4 mm. The validation of the numerical model showed that the predictions agreed well with measured results from the literature of Yang et al., and suitably simulated the development of two-phase flow patterns along the channel. We hence extended the computational fluid dynamics (CFD) simulations to assess the heat transfer and frictional characteristics of straight and converging condensed minitubes for R1234yf refrigerant at varied operating conditions of mass flux, heat flux and vapor quality, respectively.
Keywords Condensation heat transfer, Pressure drop, R1234yf, CFD