The left intake duct of the refrigerated compartment is perpendicular to the axis of the fine hole on the uniform flow plate

During the refrigerated transportation process, for every 10 ℃ increase in environmental temperature, the nutritional factors of Yangmei, such as sucrose loss of 10.5% and total acid consumption of 25%, result in a decrease in sugar and acid content, leading to a change in fruit flavor. To ensure the consistency of taste and quality of yangmei as much as possible and effectively reduce consumption rate, it is necessary to strictly control the temperature fluctuations and average diffusion level inside the refrigerated transportation carriage. Currently, unreasonable factors such as the airflow circulation control method and cargo stacking deployment in refrigerated transportation carriages result in uneven temperature fields inside the carriages, which cannot meet the transportation requirements of waxberries well. Therefore, it is necessary to study the flow field movement inside the refrigerated compartment, optimize control design parameters, and reasonably allocate the cooling capacity and airflow organization in the compartment based on the requirements of the storage characteristics of Yangmei for cold chain transportation temperature, in order to ensure the average diffusion of temperature inside the compartment.

In recent years, with the widespread application of Computational Fluid Dynamics (CFD) as a numerical calculation tool in the food industry, some scholars have adopted this method to simulate and analyze the internal flow field of refrigerated carriages, and carried out structural improvement designs for the carriages. The literature optimized the design through orthogonal experiments, introduced the evaluation index of temperature field average, and analyzed the influence of factors such as the speed of the airflow circulation fan, the porosity of the uniform flow plate, and the vertical spacing between the cargo frames on the temperature field inside the refrigerated transportation carriage. Adjust the bias of the air curtain fan at the right return air outlet in the "Cenling" area of the temperature field to achieve average control.

The left intake duct of the refrigerated compartment is perpendicular to the axis of the uniform flow plate fine hole, and the installation positions of the shelves are perpendicular to each other. Cold air enters the central channel of the frame through the damping holes of the uniform flow plate, exhibiting signs of rebound and diversion. It shows a decreasing trend from the front to the rear of the car, and vortex zones appear in the corner area of the carriage, resulting in extremely uneven flow distribution. At the same time, the aperture of the air inlet/outlet of the uniform flow plates on both sides of the refrigerated compartment, the shape/structure of the shelves, and the stacking method of waxberries determine the flow and distribution of cooling capacity inside the compartment, which are also the main factors affecting the uniformity of the temperature field. This article conducts numerical simulations on the temperature field and flow field, exploring how to improve the synergistic level of temperature gradient and flow field to achieve optimal heat transfer performance. By controlling the speed and angle of the air curtain to control the trend of the angle transition between the isotherm and the streamline, the flow field and temperature field of the cooling capacity inside the chamber are optimized, effectively reducing the highest temperature inside the chamber and making the temperature diffusion more uniform.

Set the air flow inside the chamber as a stable operating condition, ignoring radiation heat transfer from the sun and other sources. Heat transfer media such as homogeneous materials cannot be compressed, and follow the laws of continuity and energy conservation. The stable flow field of the refrigerated compartment after long-term operation can be regarded as a steady field, belonging to convective and high Reynolds number turbulent inclusions.