Flow boiling of R32 in a horizontal stainless steel tube with 6.00 mm ID. Experiments, assessment of correlations and comparison with refrigerant R410A

Refrigerant R32 is one option for the replacement of R410A in residential air conditioning and heat pump systems. This paper focus on the flow boiling characteristics of pure R32 in a single horizontal stainless steel tube with an internal diameter of 6.0 mm. A total of 437 experimental results are presented for two-phase heat transfer coefficient and frictional pressure drop and the effect of the operating parameters in terms of mass flux (from 146 to 507 kg/m2 s), saturation temperature (from 24.6 to 40.6 °C) and imposed heat flux (from 2.4 to 41.2 kW/m2) is discussed. Several heat transfer coefficient and pressure drop data of R410A obtained in the same test section are also used for comparison purposes. Finally, predictions of the most quoted flow boiling heat transfer and frictional pressure drop methods are compared to experimental data to evaluate their agreement.