Case studies on heat transfer, airflow behavior, and heat infiltration in refrigerated trucks during offloading operations

Given the increasing demand for the transportation of perishable food and medical supplies, refrigerated trucks have become a critical component of global cold chain logistics. With the transition toward electrification of these vehicles, enhancing their energy efficiency is vital for extending operational range. This study explores the thermal and flow behavior, as well as the associated heat gain, of a refrigerated truck under various offloading scenarios. Key operational parameters considered include the loading quantity, fan operation, the number of doors opened, and the frequency of offloading events. Furthermore, the effect of a simple 200-mm blocking plate was assessed as a potential strategy to mitigate thermal losses during unloading. Results showed that opening only one door under fan operation led to a temperature decrease of up to 14.3 K compared to opening two doors, yielding a 31.6% reduction in infiltration heat gain. Increasing the number of offloading events from two to four resulted in a 139% rise in infiltration heat gain. The use of the blocking plate during fan operation further reduced infiltration heat gain by 30%. These findings provide practical insights for optimizing offloading procedures and minimizing thermal losses in refrigerated trucks.