A comparative study of the flow boiling heat transfer characteristics of R410A and its alternative R447A in a horizontal smooth tube

The ternary mixture R447A is an ideal substitute of R410A due to its low global warming potential (GWP) and similar physical properties with R410A. In this paper, the flow-boiling heat transfer characteristics of R447A and R410A in a horizontal smooth tube with external diameter of 5 mm was investigated. The experimental conditions are as follows: heat flux of 5-15 kW/m 2, mass flow rate of 100-300 kg/(m 2.s), and evaporation temperature of 5-25 °C. The main research results are as follows: The heat transfer coefficient of R447A ranges from 1000 to 5000W/(m 2·K). The heat transfer coefficient of R447A demonstrates a progressive enhancement with increasing heat flux and mass flow rate. The heat transfer coefficient of R410A exceeds that of R447A by 15% to 28%, with heat flux exerting a more pronounced influence on R410A. Nucleate boiling predominates in the heat transfer process of R410A compared to R447A, while the mass flow rate has a greater impact on R447A than on R410A. R447A necessitates a higher mass flow rate for equivalent refrigeration capacity. In addition, a novel model for R447A was proposed in this study, the predictive accuracy of the model ranges from -30.21% to +45.43%, with an average deviation of +5.21% and an absolute deviation of +10.96%. Notably, 90% of the predicted values exhibit deviations within ±20% of the experimental data.