Experimental Study of Boiling Heat Transfer and Pressure Drop of R32 inside Horizontal Multiport Tube with Circular Minichannels

Abstract

  This study experimentally investigated the boiling flow heat transfer and two-phase frictional pressure drop characteristics of the refrigerant R32 in a horizontal multiport tube with circular minichannels. The boiling heat transfer coefficients and two-phase pressure drops were measured at a saturation temperature of 15 °C for mass velocities that ranged from 50 to 400 kgm^-2s^-1 and heat fluxes that ranged from 5 to 40 kWm^-2. The effects of mass velocity, heat flux, and vapor quality on the boiling heat transfer characteristics were clarified. The measured boiling heat transfer coefficients and two-phase frictional pressure drops were compared with previous correlations. Under the low mass velocity and low heat flux conditions, the boiling heat transfer characteristics differed from the previous correlations for conventional large diameter tubes. The two-phase frictional pressure drops were in good agreement with previous correlation, except for the mass velocity of 50 kgm^-2s^-1.