Abstract: Precooling is one of the important methods to protect the quality of the stored products. The optimum precoolingair velocity on a certain stacked type was analyzed based on the couple formula of the falling rate of the temperature drop, thefalling rate of the pressure drop and the change rate of the temperature of the stored products. The results were tested by theexperiments. It showed that the couple formula could meet with the experiment result, and under the experimental conditions,when the precooling velocity was about 0.9m/s to 1.5m/s, there was an optimam economical result in the pre-cooling.

Key words: temperature drop, pressure drop, precooling, cold-storage chain