R245fa Evaporation Heat Transfer and Pressure Drop in a Brazed Plate Heat Exchanger for Organic Rankine Cycle (ORC)

Abstract

Evaporator which is of great importance in Organic Rankine cycle (ORC) receives less attention compared with the ORC system itself. An evaporator selected correctly not only can improve the thermal efficiency, but also can save refrigerant. It is crucial to determine the heat transfer features of refrigerant in an evaporator. In paper presents an experimental study on the heat transfer and pressure drop of R245fa in a brazed plate heat exchanger (BPHE) for organic Rankine cycle (ORC) was carried out. The effects in terms of heat flux, refrigerant mass flux, saturation temperature, and superheat degree at the outlet of the BPHE were investigated. Experiments were conducted for refrigerant mass flux ranging from 120 to 210 kg/h at saturation temperatures ranging from 78Ž to 92 Ž. The heat flux was varied between 20 kw m-2 and 29kw m-2. The current study indicated that the heat transfer coefficients show great sensitivity to heat flux and refrigerant mass flux. However, the corresponding pressure drop increased with increasing the mass flux and heat flux.