Experimental analysis, model development and validation of a cold room designed for off-grid operation

This study focuses on the design, experimental analysis, and modeling of a cold room refrigeration system using propane as working fluid, to be deployed in off-grid applications in sub-Saharan climates. A prototype is built and tested with particular attention on the assessments of two defrosting methods: electric resistance and hot fluid. The system model combines a steady-state vapor compression model with a dynamic model of stored goods. Results show refrigerant pressure and temperature predictions within 3%, compressor power underestimated by 14.01%, and goods temperature estimated within 2 K. To assess off-grid viability, a photovoltaic system with battery storage is designed for Kinshasa, Democratic Republic of Congo, to freeze 100 kg of meat to-20 degrees C in 16 h. The system's average daily energy consumption is 3.60 kWh for electric defrosting and 3.38 kWh for hot fluid defrosting, requiring battery capacities of 10.48 kWh and 9.79 kWh, respectively. This work offers a comprehensive approach to developing efficient, off-grid cold storage systems, supporting reliable food preservation and promoting sustainable infrastructure in remote regions with limited access to electricity.