It was believed that the stacking pattern of cartons used in storage or transportation influenced the cooling rate of packed products.
To find out what this influence was, a study was undertaken and following results were obtained.
1. In the multi-stacked type of loads, the cooling rate of the products in the carton increased in accordance with cooling air flow rate. Half cooling time of 3.1 to 4.2 hours was attained with air flow of 0.23 to 0.06m
3/min/kg (Fig 1).
2. In the Vertical-vented stacked loads, remarkable cooling rate was accomplished, and the effect of opening area in a carton on the cooling rate was little under constant air flow (Fig. 2).
3. The cooling rate of middle layer of horizontal-vented stacked loads was the lowest. On the uneveness of cooling in the horizontal vented stacked loads, the difference of location in a carton had more effect than the difference of the height of the carton.
“Krisp cooling” as an example of this pattern is referred (Fig. 3).
4. The cooling rate of the products in the spaced-stack loads differed much by the location of each cartons, the difference of the half cooling time being 1.5 to 3.6 hours (Fig. 4) Optimum size of channels between stacked cartons exist.
5. The products in the spaced-stack loads was cooled more rapidly than the one in solid loads, and the products in the carton was cooled more rapidly than in the wooden box (Fig. 6).
6. The relation between the stacking patterns and their total area of void were explained. The wooden box and the carton box were compared in the time required to remove 3/4 of field heat (2Z) (Fig. 7).
7. Thermal conductivity, thermal resistance of the materials of carton and wooden boxes were compared.
The temperature of wooden boxes is much influenced by surrounding air temperature (Table 1).
8. Principle of cooling of vented-carton by chimney loading was explained.
The cooling rate increased in accordance with the cross-sectional area of chimney space and its air velocity.
The products at the middle layer of chimney loads was cooled later than the one at the upper and lower located cartons (Fig. 5).
9. The chimney load and the solid load combined with vented or nonvented cartons were compared in the cooling rate (Table 2).
The results obtained are as follows:
(vented carton in chimney loads)>
(vented carton in solid loads)=
(non-vented carton in chimney loads)
10. The method of exhausting from ceiling through the side of stacked loads had little temperature difference between upper and lower cartons of the stack (Fig. 9).
11. The method of exhausting from ceiling through the multi-stacked shallow wooden boxes with slitted bottom had uniform cooling through all layers, and the cooling rate increased in accordance with cooling air flow rate (Fig. 10)
12. Ventilation through suction tube inserted into the piled citrus was effective for rapid cooling (Fig. 11).
13. Cooling rates by the stacked patterns were collected in a table (Table 3).
抄録全体を表示