Temperature uniformity, air flow and air pressure in a 45ft reefer container: Climate chamber tests on 45ft intermodal refrigerated container PVDU380268[0]

Project partners Essers, Thermo King and Unit45 are developing a new type of 45ft reefer container. They would like to compare the performance of a first version of the new type of 45ft reefer container to a reference 45ft container. To that end a series of climate chamber tests has been performed on a reference 45ft container. In the tests the following parameters were measured and evaluated: K-value, air flow rate, distribution of air flow, static air pressure distribution, and temperature distribution in extreme ambient temperatures. The distribution of air flow, static air pressure distribution, and temperature distribution were measured for three configurations: 1. Configuration 1 (reference): standard container with standard stowage. 2. Configuration 2 (no air chute): reference + removed supply air duct. 3. Configuration 3 (23 pallets): reference + right row of pallets 90° rotated to increase space between walls and cargo from 2 to 12 cm. In these tests a dense grid with more than 50 internal temperature loggers was used, which allows a 3D comparison of temperature distribution in the different conditions. Important is the temperature uniformity requirement: for long-distance carriage of lily bulbs, the difference between the warmest and the coldest cargo temperature shall never be more than 3 °C. In all tests especially the door-end temperatures deviate from setpoint, illustrating the need to carry more supply air towards the door-end. The most important conclusion is that temperature differences inside the container are too large, especially in cooling mode. In cooling mode at Tset = 4 °C and Tamb = 40 °C, method of drive = diesel, and run mode = continuous, even in the favorable reference configuration the difference between the warmest and the coldest cargo temperature is 7.7 °C. Other important conclusions are: 1. This container’s supply air duct is susceptible to improvement, despite its significant contribution to making the temperature distribution more uniform. 2. Increasing the distance between cargo and walls from 2 to 12 cm in this container adversely effects door-end temperatures, and hence temperature uniformity.