refrigration & air conditioning

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ELEMENTS OF MECHANICAL ENGINEERING

K J INSTITUTE OF ENGINEERING AND TECHNOLOGY

-BY SIDDHARTH BEDARKER

DEEPAK SHUKLA

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Refrigeration & Air ConditioningRefrigeration & Air Conditioning

Introduction

Type of refrigeration

Refri gera tion &

AC

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IntroductionIntroduction

How does it work? Refrigeration and air conditioning is used to cool products or a building environment.

Refri gera tion &

AC

High Temperature Reservoir

Low Temperature Reservoir

R Work Input

Heat Absorbed

Heat Rejected

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Thermal energy moves from left to right through five loops of heat transfer:

How does it work?

Refri gera tion &

AC

(Bureau of Energy Efficiency, 2004)

1)

Indoor air loop

2)

Chilled water loop

3)

Refrigerant loop

4)

Condenser water loop

5)

Cooling water loop

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• Small capacity modular units of direct expansion type (50 Tons of Refrigeration)

• Centralized chilled water plants with chilled water as a secondary coolant (50 – 250 TR)

• Brine plants with brines as lower temperature, secondary coolant (>250 TR)

Refrigeration systems for industrial processes

Refri gera tion &

AC

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Training Agenda: Refrigeration & Training Agenda: Refrigeration & Air ConditioningAir Conditioning

Introduction


Types Of Air Conditioner

Refri gera tion &

AC

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Types of RefrigerationTypes of Refrigeration

• Vapour Compression Refrigeration (VCR): uses mechanical energy

• Vapour Absorption Refrigeration (VAR): uses thermal energy

Refrigeration systemsRefri gera tion &

AC

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Type of RefrigerationType of Refrigeration

Vapour Compression RefrigerationRefri gera tion &

AC

• Highly compressed fluids tend to get colder when allowed to expand

• If pressure high enough

• Compressed air hotter than source of cooling

• Expanded gas cooler than desired cold temperature

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AC

Two advantages

• Lot of heat can be removed (lot of thermal energy to change liquid to vapour)

• Heat transfer rate remains high (temperature of working fluid much lower than what is being cooled)

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AC

Refrigeration cycle

Condenser

Evaporator

High Pressure

Side

Low Pressure

Side

CompressorExpansion Device

1 2

3

4

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Vapour Compression Refrigeration/Refr igera tion &

AC

Refrigeration cycle

Low pressure liquid refrigerant in evaporator absorbs heat and changes to a gas

Condenser

Evaporator

High Pressure

Side

Low Pressure

Side


1 2

3

4

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AC

Refrigeration cycle

The superheated vapour enters the compressor where its pressure is raised

Condenser

Evaporator

High Pressure

Side

Low Pressure

Side


1 2

3

4

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AC

Refrigeration cycle

The high pressure superheated gas is cooled in several stages in the condenser

Condenser

Evaporator

High Pressure

Side

Low Pressure

Side


1 2

3

4

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AC

Refrigeration cycle

Liquid passes through expansion device, which reduces its pressure and controls the flow into the evaporator

Condenser

Evaporator

High Pressure

Side

Low Pressure

Side


1 2

3

4

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AC

Type of refrigerant

• Refrigerant determined by the required cooling temperature

• Chlorinated fluorocarbons (CFCs) or freons: R-11, R-12, R-21, R-22 and R-502

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AC

Choice of compressor, design of condenser, evaporator determined by

• Refrigerant

• Required cooling

• Load

• Ease of maintenance

• Physical space requirements

• Availability of utilities (water, power)

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Vapour Absorption RefrigerationRefri gera tion &

AC

Condenser Generator

Evaporator

AbsorberCold Side

Hot Side

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AC

Evaporator

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AC

Absorber

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Vapour Absorption Refrigeration

Refri gera tion &

AC

High pressure generator

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AC

Condenser

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Training Agenda: Refrigeration & Training Agenda: Refrigeration & Air ConditioningAir Conditioning

Introduction


Type Of Air Conditioner

Refri gera tion &

AC

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• An air conditioning system is an assembly of different part of the system used produce a specified condition of air within a require space or building.

• The basic elements of air conditioning system:--• Fans : For circulation of air• Filters : For cleaning air• Heating Elements : Heating of air(It may be electric

heater , steam , hot water.• Control System : It regulates automatically the amount

of cooling or heating.• Grill : It adjust the direction of the conditioned air to the

room.• Tray : It collects condensed water.• Refrigerating Plant : provide cooling . It consist of

compressor/generator and absorber,eveporator,condensor,expansion device(capallary tube).

Air Conditioning System

Refri gera tion &

AC

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Types Of Air ConditionerTypes Of Air Conditioner

Refri gera tion &

AC

• Window Air Conditioner

• Split Air Conditioners

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Window Air Conditioner

Refri gera tion &

AC

Working:--The air circulation system of the window air conditioner comprises of the following parts (please refer fig 4 & 5).

1) Blower: This is the small blower that is fitted behind the evaporator or cooling coil inside the assembly of the window air conditioner system. The blower sucks the air from the room which first passes over the air filter and gets filtered. The air then passes over the cooling coil and gets chilled. The blower then blows this filtered and chilled air, which passes through the supply air compartment inside the window air conditioner assembly. This air is then delivered into the room from the supply air grill of the front panel.

2) Propeller fan or the condenser fan: The condenser fan is the forced draft type of propeller fan that sucks the atmospheric air and blows it over the condenser. The hot refrigerant inside the condenser gives up the heat to the atmospheric air and its temperature reduces.

3) Fan motor: The motor inside the window air conditioner assembly is located between the condenser and the evaporator coil. It has double shaft on one side of which the blower is fitted and on the other side the condenser fan is fitted. This makes the whole assembly of the blower, the condenser fan and the motor highly compact.

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Window Air Conditioner

Refri gera tion &

AC

Split Air ConditionerThe Split Air Conditioner divided in two

parts:--(1)First part:-Include the

evaporator,filter,evaporator fan and grill. They placed inside the room.

(2)Second part:-Include Condensor ,fan,compressor.This placed out side the room.diameter tubes.therefore,small hole rquired in wall of installation of split air condition.The split air conditioning units are available in capacity range of 1 to 3 tons.

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WORKING OF SPLIT AC CONDITIONER

The fans blow air over the coils to improve their ability to dissipate heat (to the outside air) and cold (to the room being cooled).When you get into larger air-conditioning applications, its time to start looking at split-system units. A split-system air conditioner splits the hot side from the cold side of the system, as in the diagram below.

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The cold side, consisting of the expansion valve and the cold coil, is generally placed into a furnace or some other air handler. The air handler blows air through the coil and routes the air throughout the building using a series of ducts. The hot side, known as the condensing unit, lives outside the building.

http://home.howstuffworks.com/home-improvement/heating-and-cooling/furnace-maintenance.htm

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The unit consists of a long, spiral coil shaped like a cylinder. Inside the coil is a fan, to blow air through the coil, along with a weather-resistant compressor and some control logic. This approach has evolved over the years because it's low-cost, and also because it normally results in reduced noise inside the house (at the expense of increased noise outside the house). Other than the fact that the hot and cold sides are split apart and the capacity is higher (making the coils and compressor larger), there's no difference between a split-system and a window air conditioner

http://science.howstuffworks.com/nature/climate-weather/atmospheric/weather.htm

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References

http://home.howstuffworks.com/ac3.htm

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Refrigeration & Air Refrigeration & Air Conditioning SystemsConditioning Systems

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Refri gera tion &

AC

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