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Applications of Refrigeration:

 

Artcle by Dr. L.C.Singal, Prof. (ME Deptt), CEC Landran, (Mohali), Punjab (India), Formerly Prof in Chemical Engg. Deptt., Panjab University, Chandigarh

Separation of gases:

(i) Separation of air into its constituents by fractional distillation. Air is liquefied at -1910C. Liquefaction temperature of Nitrogen is -1860C and that of oxygen is -1960C.

(ii) Separation of gases in the petroleum industry (Refinery). Lowest temperature needed is -1600C and the cooling capacity needed are 10000 tons of refrigeration.

Condensation of gases:

Synthetic ammonia plants condense ammonia gas with temperatures between -200C to +100C before storage or before shipment.

Dehumidification of air:

(i)                   Low humidity is essential for the production of pure oxygen.

(ii)                 Low humidity is essential in the manufacture of pharmaceuticals, a soap, detergents and cosmetics.

Solidification of a solute:

(i) De-waxing of oil in the petroleum industry is at about -250C. Low Pressure Storage in Liquid Form:

(ii) Storing of gases in liquid form permits many times storage than in the gaseous state i.e. Natural gas is cooled to -1600C at 0.7 bars (gauge).

Process cooling: Variety of processes fall under this category i.e. to cool wax to -250C to harden it on paper.

Removal of Heat of Reaction:   Many chemical reactions are exothermic (as mentioned below) but these must take place at temperatures below atmospheric temperature. Therefore refrigeration is required to remove the heat of reaction.

(i)                   In the manufacture of viscous rayon

(ii)                 In the manufacture of Cellulose acetate

(iii)                In the manufacture of synthetic rubber

Recovery of solvents: Numerous solvents can be recovered for reuse by refrigeration

(i)                   acetone in film manufacture

(ii)                 Ccl4  in textile manufacture

(iii)                CS2 in rubber manufacture

Control of Fermentation: Heat is generated during fermentation and must be removed otherwise temperature will rise beyond control i.e. refrigeration maintains 5 to 100C

(i)                   In the manufacture of alcohol in a brewery

(ii)                 In t5he manufacture of penicillin

Cooling for preservation: Following will live longer if stored between 5 to 150C

(i)                   natural rubber

(ii)                 drugs

(iii)                explosives

 

Preservation of Dairy Products: Refrigeration can maintain quality and taste.

                        (i)         Milk 2 to 50C

                        (ii)         Ice cream -250C

                        (iii)        Butter       00C

                        (iv)        Cheese      00C

Meat and poultry products:

                        (i)         -250C in the frozen state

                        (ii)         10C for long storage

                        (iii)        Fish at -150C

Beverages: Taste is improved on serving while cold

Juice Concentration: Its water is boiled off while working at vacuum and low temperature 170C

(i)                   Orange juice

(ii)                 Apple juice

(iii)                Grape juice

(iv)                Pine apple juice etc.

Candy manufacture: Chocolate and pastry maintain quality and prevent stikyness at temperatures of 5 to 100C

Food storage and distribution:

                        (i)         Frozen meat and vegetables   -15 to -27 0C

                        (ii)         Cold storages 00C

                        (iii)        Household fridges

Cold treatment of metals:

(i)                   The cutting tool can be increased many folds by refrigerating the tool for 15 minutes at -1000C

(ii)                 Magnetic strength and stability of magnets can be improved by low temperature treatment at -800C for 8 hours.

(iii)                Hoop shrinking at low temperatures

Medical applications:

(i)                   Localized refrigeration as surgical anesthesia to provide shock less surgery.

(ii)                 Blood plasma and antibiotics are manufactured using a method called freeze drying

(iii)                Deliveries taking place in air-conditioned rooms.

(iv)                Dead bodies are preserved at -700C for few days.

Ice Skating Rinks: Artificial freezing of ice rinks and not depending on weather.

Construction work:

(i)                   Cooling of concrete by refrigeration prevents cracking especially in the constriction of dams.

(ii)                 Refrigeration cools soil to facilitate excavation.

Ice manufacturing: In ice plants

 

MISCELLANEOUS APPLICATIONS: (i) Birth of a child taking place in Air Conditioned rooms

(ii) Dead bodies are stored for few days when their family members cannot be present in time

(iii) Blood preservation

(iv) Bone marrow preservation

 

 

 

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