Experimental study on flow boiling heat transfer and pressure drop in a horizontal tube for R1234ze(E) versus R600a

This study presents flow boiling heat transfer and pressure drop characteristics of R1234ze(E) in a smooth horizontal tube with an inner diameter of 6 mm. The experiments were conducted at saturation pressures from 0.215 to 0.415 MPa, mass fluxes from 130 to 258 kg m⁻²s⁻¹ and heat fluxes from 10.6 to 74.8 kW m⁻². The influences of saturation pressure, mass flux and heat flux were analyzed. Furthermore, the performance of R1234ze(E) was compared with R600a. The results show that heat transfer coefficient and pressure drop of R600a are larger than R1234ze(E). Several well-known correlations were evaluated and the results indicate that the correlation of Fang (2013) and Yang et al. (2017) give the best fit to the heat transfer coefficient and pressure drop respectively. Finally, a new heat transfer correlation was proposed and it makes great progress in the prediction accuracy.