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

An inclusive experimental study was conducted to explore the saturated flow boiling heat transfer coefficient (HTC) and frictional pressure drop (PD_f) 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 (T_s = 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 (X_m) at increasing inlet vapor quality (0.1–0.8). The findings revealed that nucleate boiling vanquished at lower X_m values, irrespective of the working conditions, despite the fact that at higher X_m, the boiling process was dominated by convection. There was a dry-out condition inside the heat exchanger at X_m = 0.42–0.63, except when G = 60 kg m⁻² s⁻¹. The result suggested that the HTC of R290 strongly depended on X_m and T_s compared with G and q. The PD_f of R290 shows a strong dependence on T_s, G, and X_m, whereas it is less dependent on q. Moreover, PD_f increases with an increase in G, X_m, and q values, and decreases with an increase in T_s. 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.