Experimental Investigation on Bulk Condensation Characteristics of Low-GWP Refrigerants in Water-Cooled Plate Heat Exchangers with Three Flow Configurations.

Driven by the Kigali Amendment, this study experimentally investigates condensation heat transfer and frictional characteristics of R134a, R1234yf, and R290 in water-cooled brazed plate heat exchangers with I-flow, X-flow, and three-pass configurations. Tests covered refrigerant-side Reynolds numbers of 200–3000 under typical air-conditioning and heat-pump conditions. Heat transfer was evaluated using Nu/Boⁿ, while flow resistance was characterized by the two-phase friction factor. Nu/Boⁿ increased with Re, whereas the friction factor decreased rapidly before stabilizing in the turbulent region. R290 consistently delivered the best condensation heat transfer performance. The three-pass design performed best at low-to-medium Re, while X-flow provided the strongest enhancement at high Re. I-flow produced the lowest pressure drop. Overall, R290 with the three-pass exchanger offered the best thermal-hydraulic performance under conventional conditions, whereas R290 with X-flow was preferable for high mass fluxes and large heat loads, providing practical guidance for low-GWP compact condensers in practical applications.