An Experimental Study on the Convective Heat Transfer and Pressure Drop Characteristics for R1234ze(E) in Supercritical Region

In the supercritical organic Rankine cycle, the process of absorbing heat from a heat source takes place in the supercritical region. The supercritical heat exchanger, which is responsible for heat exchange between the heat source and working fluid in the supercritical region, is an important component of this cycle. The thermodynamic properties of the working fluid change rapidly based on the pseudo-critical temperature in the supercritical region. Therefore, for the design of a supercritical heat exchanger, the convective heat transfer coefficients should be obtained differently based on the pseudo-critical temperature. In this study, R1234ze(E) was used as the working fluid of the supercritical organic Rankine cycle, and the convective heat transfer coefficient and pressure drop were measured experimentally in the temperature range below the pseudo-critical temperature. In addition, correlations of the Nusselt number and Darcy's friction factor were proposed, and these correlations agree with the experimental results within +/- 20 % and +/- 10 %, respectively.