Study on Improving Internal Temperature Control Performance of Refrigerated Trucks in Temperate regions based on external phase change panels

The effectiveness of adding phase change panels inside a refrigerated truck to improve interior temperature has been widely verified. However, research on adding phase change panels to the exterior of the truck to resist environmental heat loads and thereby indirectly optimize the internal thermal environment remains relatively limited. To address temperature fluctuations and high energy consumption in refrigerated trucks under Guizhou's mild, humid climate, a passively assisted control scheme using sidewall-mounted phase change panels is proposed. Based on Guiyang's climate, a fluid-solid coupled heat transfer model is established via numerical simulation and experiments. Through single-factor and orthogonal experiments, the effects of ambient temperature, solar radiation, vehicle speed, and six PCM are analyzed. Results show: (1) Among the tested cases, the best-performing configuration is a 25 mm phase change panel combined with 55 mm polyurethane insulation. Full coverage (100%) provides the best temperature control, while 90% coverage offers a compromise between temperature control and material usage. (2) With panels, the average temperature drops 0.72 °C and cooling time is shortened by 54.3% under normal conditions; under extreme high-temperature static conditions, the average temperature drops 1.20 °C with cooling time shortened by 58.2%. (3) Environmental influence ranking: Tamb > G > V. (4) Ternary composite RT5–10-28HC performs best, improving control by 3.6% over single high-melting-point materials. This study provides references for phase change panel design in refrigerated vehicles in mild regions.