Study On Insulation Packaging Of Quick-Frozen Fresh Corn

In this research, we studied the coefficient of thermal conductivity of different thermal insulation materials, and the thermal insulation properties of insulation packaging box made of extruded polystyrene(XPS), which was aimed at developing a most suitable insulation packaging form for the quick-frozen fresh corn, in order to prolong the heat preservation time of insulation packaging for quick-frozen fresh corn.Through the hot-wire method, we measured the coefficient of thermal conductivity of thermal insulation materials, such as molding polystyrene (EPS), extruded polystyrene (XPS) and rigid polyurethane (PU), in different environmental temperatures. Then, the influence of the density of material and the environmental temperature on thermal conductivity was studied. The result showed that the thermal conductivity of foam insulation material decreased with the increase of density first, and then increased with the increase of density, indicating that existing a minimum thermal conductivity in the density range we had studied. The result also showed that the thermal conductivity of foam insulation material increased with the increase of environmental temperature, but the degree influenced by temperature was different as the different materials.According to the thermal conductivity value and cost-performance ratio, we chose extruded polystyrene (XPS) as the most suitable thermal insulation materials for the quick-frozen fresh corn. Adopting XPS foam board to make five thermal insulation packaging boxes with different thicknesses, by single factor test, we researched the influence of thickness on the thermal insulation properties of thermal insulation packaging box. The result indicated that the thermal insulation properties of thermal insulation packaging box made of XPS gradually strengthened with the increase of the thickness. When the thickness of thermal insulation packaging box less than30mm, the thickness had less influence on the thermal insulation effect. When the thickness of thermal insulation packaging box greater than30mm, the influence of thickness on the thermal insulation effect obviously increased.In this subject, we selected the thermal insulation packaging box made of XPS with the thickness of40mm as the insulation packaging for quick-frozen fresh corn. In the condition of temperature for23℃and humidity for50%, we studied the influence of mass ratio of phase change material and quick-frozen fresh corn on the thermal insulation properties of thermal insulation packaging box made of XPS. It turned out that with the increase of mass ratio, the heat preservation time of every temperature test point increased first and decreased then. When the mass ratio reached5:8, the thermal insulation properties of thermal insulation packaging box was best, and the heat preservation time of every point was longest. In the condition of temperature for23℃and humidity for50%, when the thickness of thermal insulation packaging box is40mm and the mass ratio is5:8, the heat preservation time can be effectively extended.