Search This Blog

Tuesday, 10 March 2015

Ice Refrigeration System

Ice Refrigeration System Points :ice refrigeration system For several years, melting ice has been used successfully as a refrigerant. Not too many years ago ice was the only cooling agent available for use in domestic and small commercial refrigerators: In this refrigerator the heat entering the refrigerated space from all various sources reaches the melting ice primarily by convection current set up in the air of refrigerated convection space. The air in contact with the warm product and walls of the space is heated by heat conducted to it from these materials. As the air is warmed it expands and rises to the top of the, space carrying the heat with it to the ice compartment. In passing over the ice the air is cooled as heat is conducted from the air to the ice. On cooling, the air becomes more dense and falls back into the storage space where upon it absorbs more heat and the cycling continues. This air acts as a heat transfer agent in carrying the heat from the walls and stored product to the melting ice.

In order that there may be adequate air circulation within the refrigerated space, the ice should be located near the top of the refrigerator and proper baffling should be installed to provide direct and unrestricted paths of air flow. To collect water which results from the melting, a drip pan must be located beneath the ice.

Ice entails certain disadvantages which tend to limits its usefulness as a refrigerant. These are as follows:
1. There is necessity of frequently replenishing the supply: a practice which is neither convenient nor economical. In addition there is a problem of disposing of water resulting from the melting.

2. A difficulty is experienced in controlling the rate of refrigeration, which in turn makes it difficult to maintain the desired low temperature level within the refrigerated space.

3. With ice it is not possible to obtain low temperatures required in many refrigeration applications. Ordinarily, 0°C is the minimum temperature obtainable through the melting of ice alone. In some cases, the inlet temperature of ice can be lowered to approximately — 18°C by adding sodium chloride or calcium chloride to produce a freezing mixture.

Inspite of the fact ice has several disadvantages, ice is preferable to mechanical refrigeration in some applications:

1. Fresh vegetables, fish and poultry are often packed and shipped in cracked ice to prevent dehydration and to preserve appearance.

2.Ice has tremendous eye appeal and can be used to considerable advantages in the displaying and serving of certain foods such as salads, cocktails, etc. and in chilling beverages.

No comments:

Post a Comment

Dont paste link here..