Flow Boiling of R450A, R515B, and R1234ze(E) Inside a 7.0 mm OD Microfin Tube: Experimental Comparison and Analysis of Boiling Mechanisms

A comparative analysis of the flow boiling characteristics R450A, R515B, and R1234ze(E) inside a 7.0 mm OD microfin tube was performed. The mass velocity explored from low values, starting 50 kg m−2 s−1, up to 400 heat flux tested in range 10–50 kW m−2, keeping constant saturation temperature 30 °C at inlet test section. R515B showed similar values transfer coefficient frictional pressure gradient under all investigated working conditions. R450A lower coefficient, especially high velocity, compared R1234ze(E), but gap performance between three fluids reduced flux. drops were generally than those R1234ze(E). In end, some correlations for evaluation both drop selected, estimated against experimental counterpart. Furthermore, effects nucleate convective boiling, as well glide analyzed estimated.