Heat and mass transfer in refrigerated container used for tomatoes' transportation—Numerical and laboratory investigation

摘要

To preserve vegetables fresh during long-distance transportation, it is essential to study the heat and mass transfer characteristics inside refrigerated containers with vegetables for preventing vegetables from spoiling and withered. Based on a mechanical refrigerated container filled up with tomatoes, a 3-D turbulence numerical model considering the heat and mass transfer characteristics of tomatoes was built in this paper. Then the dynamic temperature field, humidity field and water dissipation inside the container were calculated by the new built model for three different stacking methods. In addition, the numerical model was verified through laboratory investigation. The results indicate that in the steady state, the temperature field in the tomato storage area is higher and more layered than the surrounding environment area. The relative humidity in the container falls sharply in the initial period and then gradually increases and stabilizes in the end. When the container's loading rate is constant, compared with dense stacking method, the stacking method with 100 mm interval has a better effect for refrigerated transport. The temperature in the tomato storage area is lower, the relative humidity is higher, and the water dissipation of the tomatoes is less than the dense stacking method.Practical Applications A 3-D turbulence numerical model considering the heat and mass transfer characteristics of tomatoes was built to investigate the heat and mass transfer characteristics inside refrigerated containers. The difference between the numerical results calculated with the new built model and the experimental results do not exceed 2%, which is less than the 5% error limit in engineering, indicating that the numerical model established in this paper can effectively reflect the heat and moisture transfer characteristics inside mechanical refrigerated container filled with tomatoes. It can provide theoretical guidance for the optimized design of cargo stacking method in refrigerated containers. What's more, the 3-D turbulence numerical model has important guiding significance for the study of the temperature and humidity distribution inside mechanical refrigerated container, which can guide the optimal design of the container.