The necessity of developing small-scale precoohng equipment for monomer farmers was analyzed, the technical requirements of pre-cooling equipment were pointed out. On the basis of this, a new kind of small-scale precooling equipment in which cooling package is separated from refrigeration machine was proposed, single-layer and multi-layer experiments were done in an insulation package using stainless steel balls filled with water as study material. The results showed that, in single-layer experiment, the temperature variation law of stainless steel balls could be fitted with an equation of y = 22.57e-0.0023x, determination coefficient R2 = 0.984 7, 1/2, 3/4, 7/8 precooling time 39, 70 and 104 min respectively. In multi-layer experiment, the temperature of up layer balls decreased fast, while bottom balls decreased slowest. The temperature decreasing situation of topside balls was similar with that of single-layer balls, approaching to index variation law, the fitted curve equation was y = -0. 1098x + 25. 619, R2 = 0.9667; temperature increased from topside layer to lowest layer, so the bottom layer fruit and vegetable temperature should be viewed as the index whether up to setting value; 1/2, 3/4, 7/8 precooling time were 55, 91 and 130 min. The study will provide reference for development of precooling equipment in producing area.%分析了开发适合单体农户使用的小型产地预冷装置的必要性,并提出了产地预冷装置的技术要求.在此基础上,设计了一种预冷箱体与制冷设备可分离的小型产地预冷装置.以注水不锈钢小球为被冷却对象,在设置的预冷箱体中进行单层钢球、多层钢球的冷却试验.结果表明,在单层钢球试验中,钢球的温度变化规律可以用指数方程进行拟合,其方程为y=22.57e-0.0023x,判定系数R2=0.9487,在冷却过程中,1/2、3/4、7/8预冷时间分别为39、70和104min.在多层钢球试验中,上层钢球温度下降最快,下层钢球温度下降最慢,最上层钢球的降温情况与单层钢球的预冷情况相同,接近于指数变化规律,拟合后的曲线方程为y,=27.117e-0.0059x,判定系数R2=0.9122；最下层的温度变化近似为直线规律,拟合后的方程为y=-0.1098x+25.619,R2=0.9667；温度由最上层至最下层逐次上升,在实际应用中,应以下层果蔬的温度值作为是否达到预冷温度设定值来进行控制；1/2、3/4、7/8预冷时间分别为55、91和130min.该研究可为产地预冷设备的研发提供参考.
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