Saturation flow boiling characteristics of R290 (propane) inside a brazed plate heat exchanger with offset strip fins

Abstract

An inclusive experimental study was conducted to explore the saturated flow boiling heat transfer coefficient (HTC) and frictional pressure drop (PDf) features of R290 in a brazed plate heat exchanger embedded with offset strip fins with an offset length of 2 mm, fin thickness of 0.3 mm, and fin height of 2 mm. The experiment was conducted at four different saturation temperatures (Ts = 5–20 °C), three mass fluxes (G =20–60 kg m−2 s−1), four heat fluxes (q = 7.5–15 kW m−2), and eight mean vapor qualities (Xm) at increasing inlet vapor quality (0.1–0.8). The findings revealed that nucleate boiling vanquished at lower Xm values, irrespective of the working conditions, despite the fact that at higher Xm, the boiling process was dominated by convection. There was a dry-out condition inside the heat exchanger at Xm = 0.42–0.63, except when G = 60 kg m−2 s−1. The result suggested that the HTC of R290 strongly depended on Xm and Ts compared with G and q. The PDf of R290 shows a strong dependence on Ts, G, and Xm, whereas it is less dependent on q. Moreover, PDf increases with an increase in G, Xm, and q values, and decreases with an increase in Ts. Furthermore, empirical correlations for Nusselt number and friction factor, which were developed for R290, accounted for the influence of equivalent and liquid Reynolds numbers and the liquid and vapor densities with a mean absolute error of 10% and 14%, respectively.