Flow boiling heat transfer of refrigerants HFO-1234yf and HFC-134a in a chevron plate heat exchanger

HFO-1234yf has similar thermodynamic properties to HFC-134a but much lower GWP value. It is expected as a good candidate to replace the refrigerant HFC-134a in the near future. However, only very few papers have been published in the past years regarding to this new refrigerant in plate heat exchangers. This study provides an experimental comparison of refrigerants HFO-1234yf and HFC-134a flow boiling in a 6 plates chevron brazed plate heat exchanger. The effects of mass fluxes and vapor qualities was discussed. The test results show that at the lowest mass flux, liquid thermal conductivity dominate the heat transfer mechanism and therefore the heat transfer coefficients of HFC-134a are that those of HFO-1234yf. For higher mass fluxes, in addition to the liquid thermal conductivity, liquid and vapor viscosity are also important for heat transfer process. The interaction of these two effects caused the heat transfer coefficients of these two refrigerants are very close.