Two-phase modeling and performance evaluation of plate heat exchangers in ejector refrigeration systems with low-GWP refrigerants

• Models two-phase flow in plate heat exchangers for ejector refrigeration. • Assesses performance of new, low global warming potential refrigerants. • A key trade-off between heat transfer and pressure drop is identified. • R1234yf shows high thermal effectiveness but has large pressure loss. Accurate modeling of plate heat exchangers (PHEs) is essential for optimizing ejector refrigeration systems, particularly with the integration of low global warming potential (GWP) refrigerants. This study presents a comprehensive one-dimensional mathematical model for the generator, condenser, and evaporator within an ejector refrigeration system, developed using Engineering Equation Solver (EES). Each PHE is discretized into single-phase and two-phase segments, employing established empirical correlations, Muley for single-phase flow and Amalfi for phase-change processes, to ensure predictive accuracy. Model validation against published experimental data demonstrated a mean absolute percentage deviation below 15%. A parametric analysis was conducted to assess the influence of plate count on thermal and hydraulic performance across various refrigerants, including R134a, R152a, R600a, R1234yf, R1234ze(e) and R1233zd(e)). Results indicate a fundamental trade-off between heat transfer effectiveness and pressure drop. While HFC refrigerants (R134a and R152a) demonstrated superior performance in the generator and condenser, the Hydrofluoroolefin (HFO) R1234yf consistently achieved the highest effectiveness, reaching 0.9 with 100 plates; however, this came at the cost of elevated pressure losses: in the evaporator, the specific pressure drop for R1234yf was as high as 1400 Pa/m with 85 plates, posing a challenge given the ejector’s sensitivity to pressure levels. Generator pressure drops fell sharply with plate count and became negligible (< 1 kPa) beyond 125 plates. The findings suggest that no single refrigerant is universally optimal, and the performance highly depends on component-specific system interactions. Nevertheless, considering both thermal performance and environmental impact, R1234yf emerges as a promising alternative.