Cooling and condensation heat transfer of a refrigerant at high pressures in a chevron-type plate heat exchanger

In industrial fields, heat source over 130°C are widely needed, and for this development of industrial high-temperature heat pump systems has been promoted. For the heat release process in such the heat pump systems, it is considered to use of a plate heat exchanger (PHE) in which a high pressure working refrigerant flows. In this study, to examine the effect of chevron angle on the heat transfer of refrigerants at supercritical pressures and high subcritical pressures flowing in the chevron PHEs, experiments were conducted using a chevron PHE with a chevron angle 75°. The measured heat transfer coefficients were compared with the data of the three chevron PHEs with respective chevron angles 30°, 47.5° and 65° obtained previously. At a supercritical pressure, cooling heat transfer coefficient of the 75° PHE is somewhat higher than the 65° PHE at liquid-like low enthalpy region and almost the same at vapor-like high enthalpy region. While at a high subcritical pressure, condensation heat transfer coefficient of the 75° PHE is slightly higher but almost the same with the 65° PHE. From the results, the effect of chevron angle on the heat transfer at 65° and more is recognized but it is considered to be smaller than that at less than 65°. Besides, the pressure drop of the 75° PHE is markedly larger than that of the 65° PHE.