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DR. EUGENE A. ERMACProfessor

Refrigeration & Air

Conditioning

2010

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Refrigeration

Introduction

Definition

Importance of refrigeration

Classification of

refrigeration

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Refrigeration

Refrigeration is the removalof heat from a material or

space, so that its

temperature is lower thanthat of its surroundings.

Definition

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Refrigeration

When refrigerant absorbs the unwantedheat, this raises the refrigerants

temperature (Saturation Temperature)

so that it changes from a liquid to a gas

it evaporates. The system then usescondensation to release the heat and

change the refrigerant back into a liquid.

This is called Latent Heat.

Definition

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Refrigeration

Saturation Temperature

can bedefined as the temperature of a

liquid, vapor, or a solid, where if

any heat is added or removed, achange of state takes place.

Definition

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Refrigeration

Latent Heat- The heat required tochange a liquid to a gas (or the

heat that must be removed from a

gas to condense it to a liquid),without any change in

temperature.

Definition

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Refrigeration

Domestic

Commercial

Industrial

Classification

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Refrigeration

Refrigerators

Freezers

Domestic

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Refrigeration

Drinking Fountain

Coolers

Dispensers

Commercial

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Refrigeration

Ice Plant

Cold Storage

Industrial

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Refrigeration

Vapour CompressionRefrigeration (VCR): uses

mechanical energy

Vapour Absorption

Refrigeration (VAR): uses

thermal energy

Refrigeration Systems

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Refrigeration

Principal Parts:

Compression Ref. System

Compressor

Condenser

Drier Strainer

Capillary Tube

Evaporator (freezer unit)

Accumulator

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Refrigeration

Refrigeration Cycle- an interval

or period of time occupied byone round or course of events

in the same order or series.

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Refrigeration

This cycle is based on the physical

principle, that a liquid extracts heat

from the surrounding area as itexpands (boils) into a gas.

To accomplish this, the refrigerant ispumped through a closed looped pipe

system.

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Refrigeration

The closed looped pipe system

stops the refrigerant frombecoming contaminated andcontrols its stream. Therefrigerant will be both a vapor

and a liquid in the loop.

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Refrigeration

Refrigeration System Sides

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Refrigeration

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Refrigeration

Is the heart of the system.

The compressor does justwhat its name is. It

compresses the low

pressure refrigerant vaporfrom the evaporator and

compresses it into a high

pressure vapor.

The Compressor

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Refrigeration

The inlet to the compressor iscalled the Suction Line. It

brings the low pressure

vapor into the compressor.

The Compressor

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Refrigeration

After the compressor

compresses the refrigerant intoa high pressure Vapor, it

removes it to the outlet called

the Discharge Line.

The Compressor

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Refrigeration

The Discharge Line leaves

the compressor and runs tothe inlet of the condenser.

Because the refrigerant was

compressed, it is a hot highpressure vapor (as pressure

goes uptemperature goes

up).

The Condenser

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Refrigeration

The hot vapor enters the

condenser and starts to

flow through the tubes.

Cool air is blown across the

out side of the finned

tubes of the condenser

(usually by a fan or water

with a pump).

The Condenser

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Refrigeration

Since the air is cooler

than the refrigerant, heatjumps from the tubing tothe cooler air (energy

goes from hot to coldlatent heat.

The Condenser

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Refrigeration

As the heat is removed

from the refrigerant, itreaches its saturatedtemperature and starts

to flash (change states),into a high pressureliquid.

The Condenser

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Refrigeration

The high pressure liquid

leaves the condenserthrough the liquid line

and travels to the

metering device.

Sometimes running

through a filter dryer first,

to remove an dirt or

The Condenser

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Refrigeration

Metering devices regulate how muchliquid refrigerant enters the

evaporator .

Metering Devices

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Refrigeration

Common used metering devices are,

small thin copper tubes referred to

as cap tubes, thermally

controller diaphragm valves called

TXVs (thermal expansion

valves) and single opening

orifices.

Metering Devices

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Refrigeration

The metering device tries tomaintain a preset temperaturedifference or super heat,between the inlet and outletopenings of the evaporator.

Metering Devices

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Refrigeration

As the metering devices regulatesthe amount of refrigerant goinginto the evaporator, the devicelets small amounts of refrigerantout into the line and looses thehigh pressure it has behind it.

Metering Devices

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Refrigeration

Now we have a low pressure,cooler liquid refrigerant entering

the evaporative coil (pressurewent downso temperature goesdown).

Metering Devices

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Refrigeration

The evaporator is where the heatis removed from your house ,business or refrigeration box.

The Evaporator

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Refrigeration

Low pressure liquid leaves themetering device and enters theevaporator.

The Evaporator

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Refrigeration

Usually, a fan will move warm airfrom the conditioned space acrossthe evaporator finned coils.

The Evaporator

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Refrigeration

The cooler refrigerant in the evaporatortubes, absorb the warm room air. Thechange of temperature causes therefrigerant to flash or boil, andchanges from a low pressure liquid to alow pressure cold vapor.

The Evaporator

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Refrigeration

The low pressure vapor is pulledinto the compressor and the cyclestarts over.

The Evaporator

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Refrigeration

Vapour Compression Refrigeration

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Refrigeration cycle

Condenser

Evaporator

High

Pressure

Side

Low

Pressure

Side

CompressorExpansion

Device

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3

4

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Refrigeration

Vapour Compression Refrigeration

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Refrigeration cycle

Low pressure liquidrefrigerant in evaporator

absorbs heat and changes

to a gas

Condenser

Evaporator

High

Pressure

Side

Low

Pressure

Side

CompressorExpansion

Device

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3

4

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Refrigeration

Vapour Compression Refrigeration

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Refrigeration cycle

The superheated vapourenters the compressor

where its pressure is

raised

Condenser

Evaporator

High

Pressure

Side

Low

Pressure

Side

CompressorExpansion

Device

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3

4

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Refrigeration

Vapour Compression Refrigeration

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Refrigeration cycle

The high pressure

superheated gas is cooledin several stages in the

condenser

Condenser

Evaporator

High

Pressure

Side

Low

Pressure

Side

CompressorExpansion

Device

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3

4

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Refrigeration

Vapour Compression Refrigeration

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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

CompressorExpansion

Device

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3

4

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Refrigeration

Compression System Processes

Compression

Condensation

Expansion

Evaporation