Experimental Analysis and Temperature Rise Modeling of Multistage Centrifugal Pumps for Solar Ejector Refrigeration Systems

This study presents an integrated experimental–modeling investigation of the thermal behavior of a multistage centrifugal refrigerant pump in solar ejector refrigeration systems (SERS). A temperature-rise prediction model is formulated strictly from energy conservation with viscous dissipation and validated on a closed-loop test rig under variable flow rates, inlet pressures, and operating frequencies. Experiments show that the outlet temperature rise (ΔT) decays approximately exponentially with increasing flow rate, while higher operating frequency intensifies viscous-dissipation heating. The pressure difference (Δp) increases with both flow rate and frequency, whereas the overall efficiency (η) exhibits a parabolic trend, peaking at 32.6% at 37.5 Hz. The model achieves high predictive accuracy, with errors within ±0.4 °C at 25–37.5 Hz and about ±1.1 °C at 50 Hz. By constructing Δp–Q–f operating maps and coupling them with cavitation-risk analysis, safe and optimal operating zones (“best zone” and “caution zone”) are identified. These results provide quantitative guidance for pump thermal management, frequency scheduling, and system integration, enabling energy-efficient and reliable operation of solar-driven ejector refrigeration systems.