Two-phase flow dynamics during boiling of R134a refrigerant in minichannels

This study is devoted to complex experimental investigation of two-phase flow boiling of R134a refrigerant in a minichannel having a hydraulic diameter of 540 $\mu$m at heat fluxes up to 70 kW/m$^2$ and mass fluxes up to 700 kg/(m$^2$s). Flow regimes, pressure drop, heat transfer coefficient, and behavior of instabilities are analyzed as functions of vapor quality. On the basis of experimental data, the methods for calculating two-phase pressure drop in a minichannel with a diameter of about 500 $\mu$m are determined, and new correlation is proposed for estimating the heat-transfer coefficient; the region of stable boiling of the refrigerant is also determined.