Abstract
This paper presents an experimental investigation of a low-temperature ejector-based air-conditioning system designed to utilize waste heat from Combined Heat and Power (CHP) plants. The system operates with isobutane (R600a) as the working fluid and is driven by low-grade heat sources in the temperature range of 80–120 °C. A prototype experimental rig was developed to evaluate the influence of key operating parameters, including motive steam pressure and evaporator temperature, on the system’s Coefficient of Performance (COP) and entrainment ratio. The results demonstrate that the system can maintain stable operation even at ultra-low heat source temperatures, achieving a maximum COP of 0.35 under optimal conditions. The findings confirm the feasibility of using R600a in ejector-based systems for sustainable cooling applications. Furthermore, the study highlights the potential for integrating such systems into existing district heating networks to enhance overall energy efficiency. Overall, the presented results provide valuable experimental data supporting the development of sustainable, thermally driven cooling technologies that reduce reliance on grid electricity and high-GWP refrigerants.