Post on 14-Apr-2018
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BASIC CONCEPTS OF
REFRIGERATION
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REFRIGERATION
Is the science of producing and
maintaining temperatures below that of the
surrounding atmosphere.
This means the removal of the heat from a
substance to be cooled.
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Before refrigeration
To cool a warm object before refrigeration
was invented, humans placed material to
be cooled near a cold object like a block of
natural ice, or in a cool well, pond, or lake.
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iceman
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Major uses
The largest application of refrigeration, which is
the process of cooling, is for air conditioning.
Refrigeration embraces industrial refrigeration,
including the processing and preservation offood;
Removing heat from substances in chemical,
petroleum, and petrochemical plants; and
Numerous special applications such as those in
the manufacturing and construction industries.
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Specific applications
Air conditioning of medium-sized and largebuildings.
Industrial air conditioning Spot heating and cooling
Environmental laboratories Printing
Textiles
Precision parts and clean rooms
Photographic products Computer rooms
Power plants
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Specific applications
Residential air conditioning
Air conditioning of vehicles
Food storage and distribution Food processing
Dairy products
BeveragesChemical and process industries
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Special applications of refrigeration
Drinking fountains
Dehumidifiers
Ice makers Ice-skating rinks
Construction
Desalting of seawater
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Construction refrigeration
Refrigeration is sometimes used to freeze soil to
facilitate excavations. A further use of
refrigeration is in cooling huge masses of
concrete (the chemical reaction which occursduring the hardening gives off heat, which must
be removed so that it cannot cause expansion
and stress the concrete).
Concrete may be cooled by chilling the sand,gravel, water, and cement before mixing, and by
embedding chilled-water pipes in the concrete.
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Concrete cooling system
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Vapor compression refrigeration
system (Reversed Carnot Cycle)
Recall: A cycle needs four factors:
Working substance
Hot reservoir / heat source
Cold reservoir / heat sink
Engine / heat pump
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Schematic of heat engine
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Schematic of heat pump
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Parts of Basic Vapor Compression
Cycle
Compressor
Condenser
Evaporator Expansion valve
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Parts of refrigeration
Compressor- A machine used for
increasing the pressure of a gas or vapor.
The compressor does work on the system
increasing the pressure from the existingevaporator and to that existing in the
condenser.
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parts
Condenser- A heat transfer device that
reduces a thermodynamic fluid from its
vapor phase to its liquid phases.
the high pressure, high temperature vapor
that enters the condenser has heat removed
from it and as a results it is condensed back
in a liquid phase. It is where the refrigerant is liquefied and
discharges its heat to the environment.
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Parts (cont)
Evaporator any of many devices inwhich liquid is changed to the vapor stateby the addition of heat, for example,
distiller, still, dryer, water purifier, orrefrigeration system element whereevaporation proceeds at low pressure andconsequent low temperature.
heat is absorbed to boil the liquid at a lowtemperature, therefore a low pressure mustbe maintained in this section.
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parts
Throttle valve a choking device to
regulate flow of a liquid, for example, in a
pipeline, to an engine or turbine, from a
pump or compressor. the high pressure liquid from the condenser is
expanded through this valve, allowing its
pressure to drop to that existing in theevaporator.
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Schematic diagram
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Actual set-up
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Household
refrigerator
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refrigerants
Is the substance used for heat transfer in a
refrigerating system. It pucks up heat by
evaporating at a low temperature and
pressure and gives up this heat bycondensing at a higher temperature and
pressure.
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What is freon?
Is a group of organic compounds used as
refrigerants. Freon is DuPonts trade name
for its chlorofluorocarbon and
hydrochlorofluorocarbon refrigerants, usedin air conditioning and refrigeration
systems.
It is a brand name!!! duPont refrigerants!
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DuPont
DuPont pioneered much of thescience that makes airconditioning and refrigerationpossible. With over 75 years ofproven leadership inrefrigerants science and
technology we offer thebroadest range of refrigerantsolutions for new and existingequipment, and we arecommitted to leveraging TheScience of Cool to lead thesearch for new cooling
solutions that improve comfortand enhance the quality of lifearound the world.
http://refrigerants.dupont.com/Suva/en_US/science/index.htmlhttp://refrigerants.dupont.com/Suva/en_US/science/index.htmlhttp://refrigerants.dupont.com/Suva/en_US/science/index.htmlhttp://refrigerants.dupont.com/Suva/en_US/science/index.html7/30/2019 02_Basic Concepts of Refrigeration
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History of freon
Refrigerators from the late 1800s until 1929used the toxic gases, ammonia (NH3), methylchloride (CH3Cl), and sulfur dioxide (SO2), asrefrigerants. Several fatal accidents occurred in
the 1920s because of methyl chloride leakagefrom refrigerator. People started leaving theirrefrigerators in their backyards. A collaborativeeffort began between three American
corporations, Frigidaire, General Motors andDuPont to search for a less dangerous methodof refrigeration.
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In 1928, Thomas Midgley, Jr. aided by CharlesFranklin Kettering invented a "miraclecompound" called Freon. Freon representsseveral different chlorofluorocarbons, or CFCs,
which are used in commerce and industry. TheCFCs are a group of aliphatic organiccompounds containing the elements carbon andfluorine, and, in many cases, other halogens
(especially chlorine) and hydrogen. Freons arecolorless, odorless, nonflammable, noncorrosivegases or liquids.
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One ton of refrigeration(standard commercial ton of refrigeration)
The American Society of Heating,
Refrigerating and Air-Conditioning
Engineers (ASHRAE): is the transfer of
200 Btu/min, or 12,000 Btu/hr. It is thebasis of all refrigeration calculations,
whether for cold storage, air conditioning,
ice making, or ice-cream manufacture.
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Another definition
Is the equivalent to the amount of heat it
takes to melt one ton of ice in 24 hrs. thus,
which the latent heat of ice equal to 144
Btu/lb, this requires 288,000 Btu in 24 hr.or 12,000 Btu/hr or 200 Btu/min.
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Horsepower per ton
Horsepower per ton is the mechanical
input in horsepower divided by the number
of tons of refrigerating effect produced by
the unit.