Transient Energy-Exergy Analysis of a Battery-Free Solar-Phase Change Material Tomatoes Preservation System Under Tropical Condi

AbstractThis study aims to investigate the transient thermodynamic performance of a battery-free solar–phase change material (PCM) refrigeration system for tomato preservation under tropical conditions. The objective is to evaluate whether latent thermal energy storage can replace electrochemical batteries in solar-powered cold storage systems while maintaining stable storage temperatures and improving cooling autonomy.A coupled COCO–FEATool multiphysics simulation framework was developed to model the integrated photovoltaic (PV), vapor-compression refrigeration, and PCM thermal storage system. COCO was used to simulate the R-290 refrigeration cycle, while FEATool modeled transient heat transfer and PCM phase-change dynamics within the storage chamber. Energy and exergy analyses were performed to quantify solar energy utilization, refrigeration performance, and thermal storage contribution. Model reliability was verified through thermodynamic benchmarking, PCM phase-change validation, and mesh-independence tests.Results show that the R-290 refrigeration cycle operating between −10 °C and 35 °C delivered 1371 W cooling capacity with 693 W compressor power (COP = 2.0). PCM integration significantly improved thermal stability, reducing chamber temperature fluctuation from ±2.8 °C to ±0.6 °C and lowering the average chamber temperature from 16.5 °C to 6 °C. The PCM achieved a melt fraction of 0.95 and provided 17 h of cooling autonomy, compared with 3 h without PCM. The system achieved 21.8% solar-to-cooling efficiency and 22.7% exergy efficiency, while PCM storage accounted for approximately 43.6% of total refrigeration duty.The results demonstrate that latent thermal energy storage can effectively replace electrochemical batteries in small-scale solar refrigeration systems, providing reliable, low-cost cold storage for perishable produce in off-grid tropical regions and offering a promising solution for reducing postharvest agricultural losses.