What is Refrigeration?
Refrigeration contribute to raising in living standard for the people of all lands.the advancement made in refrgeration in recent years.Are the result of a team approach in which technicians, craftmen, engincers, scientists and other people pool their skills and knowiedge. The health, welfare, comfort and productivity of nations are connected with new developments in both Refrigeration and Air Conditioning field Refnigeration is essentail for food preservation, production and torage of fruits, vegetables and medicines.
The application of Refrigeration and Air conditioning is limitless. The most common use is the preservation of food. Almost all the. Products in home, in firm, in business, industries and in laboratories. Are in some way affected by refrigeration. This refrigeration has become an essential commodity in modern living.
OBJECTIVES
After studying this unit, you will be able to:
● recall early and present days uses of Refrigeration and Air conditioning.
● describe the history of Refrigeration and Air Conditioning
● define Refrigeration and Air conditioning
● mention the applications of Mcchanical Reirgeration
● explain the laws and principles of Reirigeration
LESSON CONTENTS 1. History of Refrigeration 2. Refrigeration 3. Air Conditioning 4. Scope of Refrigeration/Air Conditioning 5. Different kinds of machines 6. Principles of Refrigeration 7. Laws of Refrigeration 8. Conversion Table
HISTORY OF REFRIGERATION
The story of ice dates back as far as recorded history There was no. thoucht about using it to preserve food. Thousand vears ater the. Chinesc learned that ice improve and keep the taste of drinks and other food stuffs. So they cut the ice in winter, packed in straw and. chaff. and use it durng summer. The Egypians found that water can be cooled by placing it in porous. lars, musks and on roo tops at sunset The night breezes evaporated. the moisture which seeped through the jars, making the water inside. jars cooler. One of the first patent for a practical ice making machine was generated by Jocab Perkins an American Engineer in 1834. While progress was being made in producing ice by artificial ways. by the cnd of 9th century ice became common. place in American homes. In 1885 a German Engineer produced first absorption type machine. First mechanical domestic rerigerator was introduced in 1910. A. manually operated domestc relrigerator was introduced in 1913 and. auomatic domestic refngerator in 1918. Kehunator of USA compan. introduced lrst time automatic relrigerator equiped with hermatig. unit in 1926. the tirst scicntific Air conditioner was built in 1904 by Dr Willis Carrer who is known as father of Air Conditioning. Now let us define the air conditioning.
(a) Refrigeration It is the process of removing the heat from a body or conined space for. the purpose of reducing and maintainng the temperature below than the. atmosphenc temperature. A low boiling substance is used to remove the heat from one place to another.You would have seen that ‘evaporation’ causes boiling. In fact this is the princtple of refrigeration.
(b) Air conditioning Air Conditionng is a process of controlling certain conditions of air such as Temperature control Humidity control Air filteration Air movement Air Conditioning does all of the functions at the same time on a year round basis.
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LAWS OF REFRIGERATION
The following are the laws of refrigeration. Fluid absorbs heat while changing their form of liquid state to vapour state (evaporation/vaporization) and gives up heat while. changing their state from vapour to liquid state (condensation). ‘The temperature at which the change of state occurs is always constant during change of state, but this temperature will vary. with the change in pressure. Heat always flows from higher temperature level to lower temperature level. Selection of material of high conductivity convection tends toi equalize the temperature of the bodies adjacent to another.
Heat energy and all other encrgies are mutually convertible
APPLICATIONS OF REFRIGERATION (MECHANICAL)
Mechanical Reirigeration is widely used almost in every field. Domestic relrigeratorn, commcrcal refrigerators and comfort air conditioning sytems are such upplications for homcs, oflices, banks, hops, cinemas, theatre, hotels and restaurants, Hospitals, cold. storage, milkplants, food processing units and in manulacturing. process. A Few machines have becn listed below in which the principle of refrigeration or air conditioning is used.
1.Domestic reirigerators 2.Deep freezers 3.Water coolers 4.Bottle coolers 5.Display cases 6.Cold stores 7.Window Air Conditioners 8.Split Air Conditoning system