Design of cold storage structure for sixteen tonnes onion.

Cold storage is an important method for storing onions in fresh and wholesome state for a longer period. Small cold storage for storing sixteen tonnes of onion at 1°C was designed to reduce post-harvest losses of onions and ensure a better return to small and marginal farmers. The polypropylene plastic mesh bags of 50 kg capacity were selected for onion storage with dimensions of 94 cm x 57 cm x 35 cm. The number of bags was found to be 3200 for storage of sixteen tonnes (16 MT) of onions. Considering 8 layers of bags stacked on wooden pallets, the stack height was obtained as 2.8 m. The inside and outside dimension of onion cold storage was was 8.3 m x 5.5 m x 4 m and 9 m x 6.3 m x 4.7 m in length, width and height, respectively with 10 stacks in 8 layers. The volume of cold storage was found to be 1802.6 m³. The construction and insulating materials selected were polyurethane sheet, PUF, polythene sheet, PCC, PVC panels, brick, etc., for floors, walls, door and roof for cooling load calculation. The cooling load was calculated considering all the possible heat sources. The total cooling load was found to be 2052770.6 kJ/day with 85.88% product heat load, 5.61% transmission heat load and 4.02% air infiltration load of total heat load. The cooling load for cooling sixteen tonnes of onions was found to be 9.5 tonnes which would be helpful in the selection of appropriate refrigeration systems by farmers and traders. [ABSTRACT FROM AUTHOR]