REFRIGERATION & AIR-CONDITIONING Prepared by SREEJITH K. SREEJITH K. APME APME JECC JECC

Basics of Mechanical Engineering (SK/ APME)2

REFRIGERATION Refrigeration :- It is the science of producing and maintaining temperatures below that of the surrounding atmosphere. It is the process of removing heat from a substance which is to be cooled. Refrigeration means cooling or removal of heat from a system. The system that is employed to maintain a lower temperature is called a Refrigeration System. Basics of Mechanical Engineering (SK/ APME)3

Refrigeration is generally produced in one of the following three ways:- By melting of a solid By sublimation of a solid By evaporation of a fluid Most of the commercial refrigeration is produced by the evaporation of a liquid called the refrigerant. The working fluid used in a refrigeration system is known as refrigerant. Basics of Mechanical Engineering (SK/ APME)4

Refrigeration can be obtained by :- Natural method Artificial method (Mechanical Refrigeration) Natural Method:- It include melting of ice. Mechanical Refrigeration :- It include evaporation of liquid refrigerant and its circuit includes the equipments like compressor, condenser, expansion device & evaporator. Basics of Mechanical Engineering (SK/ APME)5

Applications of Refrigeration 1. Ice making. 2. Preservation of food products, beverages. 3. Medical applications:- Manufacture and preservation of medicines, Surgery, Preservation of blood and human tissues. 4. Comfort air conditioning of auditoriums, hospitals, residences, hotels, offices. 5. Storage and transportation of food stuffs such as meat, dairy product, fish, fruit, vegetables and fruit juices etc. 6. Industrial air-conditioning. 7.Wide applications in aircrafts, submarine ships and rockets etc. 6

AIR-CONDITIONING Basics of Mechanical Engineering (SK/ APME)7

AIR-CONDITIONING Air-Conditioning :- It is science of producing air at a specified condition, within a required space of building. Air-Conditioning includes control of temperature, humidity, motion, purity of the air and supply it to the enclosed space at a desired velocity. The system that is employed for air-conditioning is called as an Air-Conditioning System. Basics of Mechanical Engineering (SK/ APME)8

Applications of Air-Conditioning To provide; Comfort Air-Conditioning :- It is meant for human comfort. It provides comfortable & healthy conditions for the occupants in residences, theaters, hospitals, offices, railway coaches. Industrial Air-Conditioning :- It is used for improving the quality of the manufactured materials. It increases the working efficiency of the employees in the factories. Basics of Mechanical Engineering (SK/ APME)9

Classification of Air-Conditioning Systems According to the arrangement of equipment:- Unitary system Central system According to the purpose:- Comfort air-conditioning system Industrial air-conditioning system According to the purpose:- Winter air-conditioning system Summer air-conditioning system Year around air-conditioning system Basics of Mechanical Engineering (SK/ APME)10

Main parts of the Air-Conditioning Systems 1. Fan :- for moving air. 2. Filter :- for cleaning air. 3. Supply duct :- to carry air from the fan to the supply outlet. 4. Supply outlet :- to distribute the air evenly in the room. 5. Space to be conditioned:-It should be an enclosed space. 6. Return outlet:-to take up or return the room air. 7. Return duct :- to carry room air from the return outlet back to the air-conditioner. 11

8. Cooling coil or Heating chamber :- to provide the necessary cooling or heating of air. 9. Means for Dehumidification or Humidification :- to dehumidify or to humidify the air. 9. Control system :- to control the air-conditioning system and to regulate automatically the amount of cooling or warming. 12

Unitary Air-Conditioning System (WINDOW AIR-CONDITIONER) 13

Basics of Mechanical Engineering (SK/ APME)14

Working of a Unitary Air-Conditioning System (WINDOW AIR-CONDITIONER) Some part of the returned air from the conditioned space, carried through the return duct is exhausted outdoors, the remaining is mixed up with some amount of fresh filtered air  It is then passed over the cooling coil, get cooled, dehumidified and the fan will then move this cool air through the supply duct and discharge it into the conditioned space through the supply outlet  While the air from the conditioned space is taken back through the return outlet and carried it back to the air- conditioner. 15

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