葡萄差压通风预冷影响参数的试验研究

果蔬差压通风预冷包装箱的开孔大小及包装箱两侧的压差是影响预冷速度、冷却均匀性的重要参数。本文对不同开孔大小、不同压差工况下葡萄差压通风预冷过程进行了试验研究，分析了它们对葡萄冷却速度、冷却均匀性的影响。结果表明，开孔面积的增加有利于加强冷风的横向流动扩散；压差的增大有利于提高冷风的径向渗透性。增大开孔直径和压差可以不同程度地缩短葡萄的7/8冷却时间、在一定条件下改善冷却均匀性。对于该试验采用的葡萄包装箱，综合考虑预冷速度、冷却均匀性以及预冷后葡萄的温升速度、干耗等因素，开孔直径在28 mm左右、压差保持在100 Pa左右为宜。

Experimental study on parameters affecting grape pressure pre-cooling

The vent hole size and the pressure drop are the important parameters which affect cooling rate and cooling uniformity in pressure pre-cooling of fruit and vegetable. Experimental investigations of grape pressure pre-cooling were conducted with different vent hole sizes and pressure drop. The effect of parameters on cooling rate and cooling uniformity were analyzed. The results show that horizontal diffusion of cooling air enhances with the increasing of vent hole size, and the increasement of pressure drop benefits the improvement of the vertical permeability of the air flow. The increasement of vent hole size and the pressure drop both shorten the 7/8 cooling time in varying degrees. The cooling uniformity is also improved in the same conditions. It is reasonable for the grape carton provided in this experiment to choose the vent hole diameter about 28 mm and the pressure drop about 100 Pa, considering the pre-cooling experiment results and other factors.