Thermoelectric and Solar Photovoltaic Synergy for Optimized Transcritical CO₂ Refrigeration in Hot Climates

Traditional transcritical CO₂ refrigeration cycles are energy-intensive, and their efficiency is influenced by outdoor conditions. This study presents a novel technique to enhance the efficiency of these cycles by integrating a thermoelectric subcooler tailored to Jordan's climate. The transcritical CO₂ refrigeration cycle, with a nominal refrigeration capacity of 14 kW, was modeled using engineering equation solver software. A key aspect of this study is the incorporation of solar energy through a custom-designed photovoltaic (PV) system to power the refrigeration cycle, contributing to sustainable cooling technology. Key performance indicators, including refrigeration capacity, power consumption, and coefficient of performance (COP), were thoroughly investigated across varying parameters, such as gas cooler pressure (8000–13,000 kPa), evaporation temperature (−15°C to 15°C), ambient temperature (28°C–35°C), current supply (5–15 A), and the number of thermoelectric pairs (50–150). Results showed that increasing the gas cooling pressure increased refrigeration capacity by approximately 79%. At a gas cooling pressure of 9000 kPa, the thermoelectric subcooler increased refrigeration capacity by 55%. Increasing the evaporation temperature improved the COP by approximately 133% and reduced power consumption by 68%. At an evaporation temperature of −15°C, the thermoelectric subcooler improved performance by 12%. Lowering the ambient temperature also enhanced COP by 68% and reduced the power consumption by 35%. At a 35°C ambient temperature, the subcooler improved COP by 8%. Experimental validation showed a 6% average deviation between simulation and experimental results for COP. The on-grid PV system designed with PVsyst software successfully met the cycle's energy demands, achieving 45.3% energy savings.