Study of Different Storage Structures

8/4/2019 Study of Different Storage Structures

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Study of different storagestructures

Presented by:Kavya shree M.GMK 815


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Storage structures:storage is one of the most important aspects of the postharvest handling of fruits and vegetables . The main objectof storage of fresh fruits and vegetables is to extend theirperiod of availability. A substantial quantity of thesecommodities go waste in our country due to lack of properstorage facilities. Orderly marketing of horticulturalproduce requires some storage facilities to balance betweenproduct harvest and sales as well as long term storage toextend marketing beyond the end of the harvest season.


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The objectives of storages :

1.To reduce physiological activity of

fruits and vegetables by maintainingthe lowest temperature that will notcause chilling injury and by controlling

atmospheric composition.2.Reduce the growth of microorganismsby maintaining low temperatures.


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3.Prevent drying of fruits and

vegetables by reducing the differencebetween fruits and air temperaturesand maintaining high humidity in the

storage room.


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cool store:

Here temperature is broughtdown by taking out the heatwith the help of mechanical

refrigeration.The expanded gas is then compressedThe heat is removed from theCompressed gas by means of running water.The ideal environmental condition for freshproduce in storage is the lowest temperature which doesnot cause chilling injury to the produce.A small temperature difference between the cooling coiland the stored fruits is required to maintain an adequate

control of relative humidity in a storage room.


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In order to increase relativehumidity, water may be sprayedInto the controlled storageChamber.

The storage life of fruits and

vegetables varies inversely withthe rate of respiration andevolution of heat.


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ice bank cooler:In this system, a bank of iceis built up with a relativelysmall refrigeration plant.The ice is accumulated on

extended surface plates,which are suspended in a tankof water.The water surrounding the ice is pumped to the top of a

cooling tower and falls through the tower passing overthe extended surface, giving a large surface area forheat exchange.The air leaving the tower maintains high humidity.


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Once the initial cooling is complete the store maintains atemperature of 0.5-0.8*c and relative humidity of98 per cent.


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low cost storage:

Low cost storage system has a great significancein India since other advanced storage systemswork out to be extremely expensive. Most of the

low cost storage structures are built by takingthe advantage of natural cooling.

There are two types of low cost storages:1) clamps and2) celler


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Clamps:


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Celler:

E l


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Evaporative cooling:Evaporative cooling occurs

when air, that is notsaturated with watervapour is blown across anywet surface.

The lowest temperature,that can be reached by theevaporation of water is called

the wet bulb temperature.It has considerable potentials for pre cooling and evenstorage of fruits.The principles of evaporative cooling can be gainfullyutilized for storage of fresh produce.


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Z l h b


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Zero energy cool chamber:This is based on the principles

of evaporative cooling.These structures have beenmade from cheap, locallyavailable raw materials, such as

brick, sand, bamboo, gunnycloth, etc., with a source ofwater supply. The floor ofstorage space is made with single layer bricks, the sidewalls with a double layer of bricks. The space (7.5 cm)between the bricks is filled with river bed sand.

The top of the storage space is covered with gunny clothin a bamboo structure.


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Refrigeration system :The refrigeration cycle in the

compression system is most widelyused system of refrigeration consistsessentially of:

1)The expansion device for thethrottling of pressurereduction effect.2)The cooler or the evaporator for thevapourisation and cooling

effect.3)The compressor in which thecompression of the vapour to the optimum pressure iseffected.

4)The condenser wherein the compressed vapour of therefri erant is li uified.


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Big size cool chamber :The low cost big size cool chamber has been

designed and constructed with a double brick wallhaving cavity filled with river bed sand.The bottom of the chamber is provided with fourDucts which are submerged in wet sand.

The floor the chamber is made of wooden plankswith provision of the entry of fresh air throughthe duct.An exhaust fan has been provided at the top ofventilation purpose.The trial with big size cool chamber showed thatIt could bring down the temperature by 8-10 c.


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Night time cooling :In some parts of the country there are

significant differences between night andday temperatures allowing night timeventilation to be a good sources of cold.

High altitude cooling :High altitude can also be a source of cold.air temperature decreases by 10 c (18 F)every 1km (0.62 miles) increase inaltitude. It is not possible to bring thisair down to ground level because itnaturally heats up as it drops in altitude.


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Thank you

Study of Different Storage Structures

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