Applications of rac
- 1. Applications of RAC By Onkar V. Bichkar
- 2. Domestic refrigerator • Preservation of food and reducing waste • Storage temperature 00C -40C • Single door double door refrigerant • VCC and VAS R-12 or R-22 • 60-100mm Insulation glass fiber or thermo Cole. For about 200mm for freezer
- 3. • Defrosting of refrigerant : - • Manual defrosting: putting off refrigerator • Push button: thermostat • Double door refrigerator:- general compartment:-natural cycle defrost Amount of frost after defrost cycle can get collected bellow evaporator freezer compartment: manual defrosting Temp. of frozen food should not go above frzeeing point so defrosting is carryout when freezer is empty
- 4. • Control in refrigerator • Starting relay: provide starting torque and disconnect starting winding when motor speed increases • Overload Protector: Protect the compressor motor winding from damage • Thermostat: bulb of thermostat charged with refrigerant and it contracts When particular temp. reached
- 6. Water cooler • Water available at constant temperature 70 -130C irrespective of ambient temperature with the help of thermostatic switch • Storage type water cooler: evaporator coils are soldered on to the walls of tank • Tank may be galvanized steel or stainless steel sheet • Reservoir of cold storage all the time • Water level is maintained by float valve
- 7. • Instantaneous type water cooler: cylindrical wound coil are bonded together by soldering • Bottle type water cooler : • Pressure type water cooler: Self- contained remote :
- 8. Dairy • Reduce bacterial growth • Pasteurization of milk : Water heating or steam heating (620) • Cooling by chilled water (40 -50C) • Fat content: formation of cheese (40C) • Ice cream : pasteurization and homogenization • Hardening
- 9. Food Preservation What is food preservation? Retaining food over a period of time without being contaminated by pathogenic organisms or chemicals and without losing its colour, texture, flavour and nutritious value. Why food preservation? • Seasonal availability of food • Different type of food at different locations
- 10. Food Product Average Useful (days) Storage life 0oC 22oC 38oC Meat 6-10 1 < 1 Fish 2-7 1 < 1 Poultry 5-18 1 < 1 Dry meats and fish > 1000 > 350 & < 1000 >100 & < 350 Fruits 2 - 180 1 – 20 1 – 7 Dry fruits > 1000 > 350 & < 1000 >100 & < 350 Leafy vegetables 3 - 20 1 – 7 1 – 3
- 11. Advantages: Increases the shelf life of food Retain the quality of food – colour, texture, flavour & nutrition value Increases food supply Adds variety to the food decreases wastage of food
- 12. Cold storage • To store food products after processing • Prefabricated insulated panels • Air tight door in sandwich construction • Safety anti-locking arrangement • Temperatures – positive or sub-zero • Layout – air lock, sorting-cum-intermediate storage area, store compartments • Important points – temperature, RH, air motion, product mix, duration
- 13. Air handling unit • Fresh air duct • Return air duct • Filter • Cooling coil • Heating coil
- 15. Types of Freezer • Contact or plate freezer: hydraulic piston compresses the packages of product between plate • Inlet freezer: Product is placed on top of belt and brine refrigerant sprayed bottom of belt
- 16. • Spiral freezer: increased belt length compare to floor area it allows product to remain for longer time in freezer • Air blast freezer: refrigerant coil are located overhead fan circulating the air over the product at 50-150 m/min
- 17. Ice Plant • Water treatment for making ice: white and milky appearance is due to air and dissolved gasses that have to be removed • Brines: sodium chloride: used when cooling surface should not exposed to damage when cooling occur calcium chloride: used shell tubular cooler • Brine temp maintained -120 to -70c and ammonia coil temp -150c to -100c at 1.3-2 bar
- 18. • Freezing tank: constructed of 6mm steel plate, water level below the brine level by 25mm • Contains freezing coils equally distributed through out the tank and submerged in brine • Ice can: fabricated from galvanized sheet by single riveting, they made heavy to avoid floating
- 19. Evaporative cooling • Cooling of air is result of transferring sensible heat of air to evaporative water. This sensible heat is transferred in the form of latent heat • Evaporative cooling considered as adiabatic system
- 20. Air conditioning • Air conditioning is the process of altering the properties of air (primarily temperature and humidity) to more favorable conditions. • More generally, air conditioning can refer to any form of technological cooling, heating, ventilation, or disinfection that modifies the condition of air.
- 21. Types of air conditioning • HVAC designer will recommend different types of air conditioning systems for different applications. most commonly using are: • 1)Window air conditioner: is the most commonly used air conditioner for single rooms. In this air conditioner all the components, namely the compressor, condenser, expansion valve or coil, evaporator and cooling coil are enclosed in a single box. This unit is fitted in a opening made in the wall of the room, or more commonly a window sill
- 23. 2) Split Air Conditioner: • The split air conditioner comprises of two parts: the outdoor unit and the indoor unit. The outdoor unit, fitted outside the room, houses components like the compressor, condenser and expansion valve. The indoor unit comprises the evaporator or cooling coil and the cooling fan. For this unit you don’t have to make any slot in the wall of the room. Further, present day split units have aesthetic appeal and do not take up as much space as a window unit. A split air conditioner can be used to cool one or two rooms.
- 24. • Packaged Air Conditioner • An HVAC designer will suggest this type of air conditioner which is used to cool more than two rooms or a larger space at home or office. • There are two possible arrangements with the package unit. In the first one, all the components, namely the compressor, condenser (which can be air cooled or water cooled), expansion valve and evaporator are housed in a single box. • The cooled air is thrown by the high capacity blower, and it flows through the ducts laid through various rooms. In the second arrangement, the compressor and condenser are housed in one casing. The compressed gas passes through individual units, comprised of the expansion valve and cooling coil, located in various rooms.
- 26. 4) Central Air Conditioning System • Central air conditioning is used for cooling big buildings, houses, offices, entire hotels, gyms, movie theaters, factories etc. • If the whole building is to be air conditioned, HVAC engineers find that putting individual units in each of the rooms is very expensive making this a better option.
- 27. • A central air conditioning system is comprised of a huge compressor that has the capacity to produce hundreds of tons of air conditioning. • eg. Hospital and multiplex