Experimental study on temperature field distribution characteristics in fresh-keeping transportation

A special test platform based on pressure difference principle was established to investigate the temperature distribution in fresh-keeping transportation room. The effects of airflow velocity and length of return airway, aperture ratio, stack mode, and ventilation slot on the characteristics of temperature distribution in fresh-keeping container were analyzed by varying the experimental levels. The results indicated that better temperature distribution homogeneity obtained with greater velocity and longer return airway. Stack mode had great effect on the temperature distribution. When the stack mode was adopted with interspaces in the middle and two sides, the temperature distribution homogeneity was the best. The aperture ratio had notable effect on temperature distribution homogeneity. The temperature distribution was better with air duct system in the fresh-keeping room than that without air duct system. Under the condition with air velocity of 8 m/s, the length of return airway of 1.5 m, the aperture ratio of 16.11%, the stack mode with interspaces in the middle and two sides, and with ventilation slot, the temperature distribution homogeneity was better with the temperature standard deviation of 1.15℃ and 2.04℃ in longitudinal section and cross section of preservation room respectively. The research achievements are instructive to optimization design of the structure of fresh-keeping room.