Numerical simulation and experiment of temperature field distribution in box of cold plate refrigerated truck

Refrigerated transportation is an important for the cold chain of subsidiary agricultural products. As resource shortage becoming more serious and environmental disciplines more strict, an environmentally protecting and energy-saving cold plate refrigerated truck, which is also multi-functional in heat preservation and refrigeration, is urgently needed by refrigerated transportation. Cold plate refrigerated truck is rapidly expanding in recent years. Due to the outside thermal environment, the temperature of cargo area has a steady increase and uneven distribution, which has a negative influence on the quality of refrigerated cargoes. Therefore, ensuring a uniform temperature field distribution of cargo area is the critical issue to improve the quality of transported cargoes. The temperature distribution of cold plate refrigerated truck is one of the key factors affecting its storage and transportation quality. A uniform temperature field can keep goods fresh during transportation. Computational fluid dynamics (CFD) is more and more widely used in refrigeration at present, and many studies have demonstrated the effectiveness of CFD in simulation analysis for the heat transfer field. Buoyancy lift is the volume force caused by non-uniform faces in each part of the fluid’s density. The heat exchange of cold plate can be deemed as the natural heat exchange in a vast space that owns an internal heat source. In this paper, the interior temperature field of an empty container was calculated by means of numerical modeling and the effect of two stacking ways on temperature field and flow field in cargo area was also analyzed. k-ε model and simple algorithm combined with Boussinesq assumption was used to simulate the three-dimension temperature distribution in cold plat refrigerated truck. In order to know the effect of different stack methods on temperature field and flow field in cargo area, stack methods were divided into two ways including close stacking and intermediated stacking in this paper. To better display the simulated results, three sections were selected along truck’s length direction and one section alone width direction as the research surface of computational simulation. This study revealed the general rules and influencing factors of temperature field in cold plate refrigerated truck, which can provide a reference for the optimization design and the selection of stack method in cold plate refrigerated truck. Simulation result showed that the temperature of container roof was always at a relatively high level. In this model, the temperature field and fluid field of the refrigerated truck were symmetrical both along the length and the width direction. The highest temperature difference in cargo area reached 18℃, which was disadvantage to storage and transportation quality. It is hard to form a uniform air and temperature field only by the natural convection depended on temperature difference in cold plate refrigerated truck. It's recommended to install cold plates on top of container and to find proper ventilation methods that can strengthen heat convection between cold air and goods, improving the cooling speed of cold plate refrigerated truck. Method of contrast verification was used to verify the correctness of the model in this paper. And the deviation of experimental data and simulated result was not beyond the scope of permission, which showed that the model was appropriate to the simulation of the temperature distribution in cold plate refrigerated truck.