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R1 Fundamentals of Refrigeration
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 R1 Fundamentals of Refrigeration #2 Introduction to Refrigeration Systems © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Example of Elementary Refrigeration
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 Example of Elementary Refrigeration Place a tank of refrigerant inside a closed box. The box and refrigerant are the same temperature (equilibrium). © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Elementary Refrigerator Equilibrium
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 R22 tank inside Elementary Refrigerator Equilibrium R22 145 psig 80 80 80 Equilibrium © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Begin elementary refrigeration
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 Begin elementary refrigeration Release refrigerant outside the box. (Note: this is theoretical, EPA regulations do not allow releasing refrigerant into the atmosphere.) What do you suppose happens to the: Pressure in the tank? Temperature of the refrigerant? Temperature in the box? © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Pressure drops, temperature drops Pressure Drop
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 Tank pressure falls Release Pressure R22 tank Pressure drops, temperature drops Pressure Drop 100 psig 145 psg Vent outside box 80 60 80 70 Box cools Tank absorbs box heat R22 Tank cools 80 60 Refrigerant starts boiling As pressure drops, temperature drops, box cools. © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Refrigerant is too expensive to waste
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 Refrigerant is too expensive to waste How can we recover the refrigerant? © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Vapor captured in outside tank
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 Vapor captured in outside tank 5/7/2018 R22 tank Vapor pressure rises with ambient 145 psig 100 psig 100 psig 60 60 Check valve 80 70 80 R22 Vapor rises to ambient temperature 60 © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Changing vapor back to a liquid
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 Changing vapor back to a liquid Increase the vapor pressure Example: 100 psig to 225 psig This increases the vapor‘s temperature Example: 80° to 110° 80° ambient air is cooler than the vapor The vapor condenses to a liquid © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Increase pressure to condense vapor to liquid
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 R22 tank 225 psig 145 psig 100 psig 60 70 80 Cooler ambient air condenses vapor to liquid R22 80 110 Increased pressure = increased temperature © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Return liquid to original tank
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 Return liquid to original tank Higher pressure liquid will returned to the original tank. The hose acts as a metering device, lowering the liquid pressure and temperature. © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Return liquid to original tank
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 R22 tank 225 psig 100 psig 60 70 R22 110 80 110 © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Names for Components & Piping
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 Names for Components & Piping Compressor Discharge line Condenser Liquid line Metering Device Evaporator Suction line © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Basic Components and Piping
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 Basic Components and Piping Discharge Line Compressor Condenser Suction Line Metering Device Liquid Line Evaporator © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Refrigeration System “Baseball Diamond”
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 Refrigeration System “Baseball Diamond” There are 4 basic components Pipes connects them Half the system is high pressure Half the system is low pressure © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Basic Components “Baseball Diamond” Low Side High Side Metering Device
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 Basic Components 5/7/2018 Metering Device “Baseball Diamond” Low Side High Side Liquid Line Evaporator Condenser Discharge Line Suction Line Compressor © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Simple A/C System Illustration:
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 Simple A/C System Illustration: A compressor + two tanks + metering device The following simple system illustrates: High pressure refrigerant temperatures drop as: discharge gas cools, then condenses as heat is rejected, then subcools before entering the TEV. Low pressure refrigerant temperatures rise as: Liquid vaporizes as it absorbs heat in the evaporator Then superheats after all refrigerant has evaporated © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Simple A/C System Compressor SuperHeat SubCool 278# 69# 278 psig 69
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 Simple A/C System 5/7/2018 AMBIENT AIR 95o 278 psig 69 psig RETURN AIR 75o 175o 60o 165o Compressor 50o SuperHeat 125o 40o 278# 69# 125o This is a simplified Air Conditioning system. Suppose we have a tank of R22 on the right and release it into a room. The tank drops in pressure and temperature, absorbing heat from the air surrounding the tank. The loss of refrigerant can be prevented by using a compressor to suck the heated refrigerant into itself. Because we need to have refrigerant return to a liquid state before it can be used for cooling we must compress it first. This raises the temperature of the vapor well above the room temperature. The room air passing over the left tank will condense the hot vapor into a liquid. The liquid then goes through a metering device dropping the pressure and temperature below that of the room. The right tank can absorb the heat of the room, starting the cycle all over again. NOTE: The compressor and the metering devices are the dividing lines between the high pressure and low pressure sides of the system. SubCool 115o 40o 105o 40o © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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“Standard” A/C System Compressor discharges hot gas
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 “Standard” A/C System Compressor discharges hot gas Gas condenses to liquid Metering device lowers pressure Refrigerant vaporizes Returns to compressor © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Standard A/C System R-22 69 psig 278 psig 175º 40º 60º 125º 125º 115º
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 Standard A/C System R-22 5/7/2018 69 psig 278 psig 175º 40º 60º 125º CONDENSER 125º EVAPORATOR 115º 40º Refrigeration Cycle for a Typical R22 A/C System High Side: High pressure vapor leaves the compressor at a high temperature. When it enters the condenser it first gets rid of the sensible heat of compression and motor heat it picked up in the compressor. This is known as de-superheating. Once it gets rid of that sensible heat it reaches its condensing temperature. In our example, when the vapor has reached 125º it starts condensing into a liquid (changes state) as it rejects the latent heat it picked up in the evaporator. Any additional cooling of the liquid before it leaves the condenser without a change of state is called subcooling. It often picks up additional subcooling in the liquid line before the metering device. Low Side: As it passes through the metering device the high temperature liquid drops in pressure and temperature as it changes to a dense vapor containing tiny droplets of liquid. About 25% of the liquid flashes off dropping the temperature of the remaining liquid from 115º to 40º. That temperature (evaporating temperature) remains the same through the evaporator absorbing latent heat from the refrigerated space as it boils off. When all the refrigerant is boiled off, or vaporized, it is now a “saturated vapor”. Any additional heat it picks up after that is called superheat because only sensible heat can be absorbed when there is no change of state. The vapor continues through the suction line picking up superheat until it gets to the compressor where the cycle starts all over. 50º AMBIENT AIR 95o RETURN AIR 75o © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Fully Condensed Liquid
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 Standard A/C System R-22 5/7/2018 Total Superheat 20° 69 psig 278 psig Super Heated Vapor 175º 40º 60º 125º Evaporation Starts CONDENSER Condensing Starts 125º EVAPORATOR Fully Evaporated 115º 40º Fully Condensed Liquid Coil Superheat 10° 50º Sub-Cooled Liquid AMBIENT AIR 95o RETURN AIR 75o © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Commercial Refrigeration System
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 Commercial Refrigeration System Compare A/C to refrigeration: Different “high side”? Why or why not? Different “low side”? Why or why not © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Typical Walk-In Refrigerator (R22)
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 50 psig 280 psig 175º 25º 45º TEV 125º CONDENSER 125º EVAPORATOR 115º 25º Refrigeration Cycle for a walk-in refrigerator using R22 Note: the main difference between A/C and refrigeration is the evaporator temperature. The condensing temperatures are the same, except freezers and high efficiency A/C units. High Side: High pressure vapor leaves the compressor at a high temperature. When it enters the condenser it first gets rid of the sensible heat of compression and motor heat it picked up in the compressor. This is known as de-superheating. Once it gets rid of that sensible heat it reaches its condensing temperature. In our example, when the vapor has reached 125º it starts condensing into a liquid (changes state) as it rejects the latent heat it picked up in the evaporator. Any additional cooling of the liquid before it leaves the condenser without a change of state is called subcooling. It often picks up additional subcooling in the liquid line before the metering device. Low Side: As it passes through the metering device the high temperature liquid drops in pressure and temperature as it changes to a dense vapor containing tiny droplets of liquid. About 25% of the liquid flashes off dropping the temperature of the remaining liquid from 115º to 25º. That temperature (evaporating temperature) remains the same through the evaporator absorbing latent heat from the refrigerated space as it boils off. When all the refrigerant is boiled off, or vaporized, it is now a “saturated vapor”. Any additional heat it picks up after that is called superheat because only sensible heat can be absorbed when there is no change of state. The vapor continues through the suction line picking up superheat until it gets to the compressor where the cycle starts all over. 35º AMBIENT AIR 95o BOX TEMPERATURE 35 © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Typical Walk-In Refrigerator (R22)
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 Typical Walk-In Refrigerator (R22) 5/7/2018 Total Superheat 20° 50 psig 280 psig Super Heated Vapor 175º 25º 45º TEV 125º Evaporation Starts CONDENSER Condensing Starts 125º EVAPORATOR Fully Evaporated 115º 25º Fully Condensed Liquid Coil Superheat 10° 35º Sub-Cooled Liquid AMBIENT AIR 95o BOX TEMPERATURE 35 © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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Refrigeration Systems
R1 Fundamentals of Refrigeration - Subject 2 Introduction to Refrigeration Systems v1.1 5/7/2018 End of Intro to Refrigeration Systems © 2004 Refrigeration Training Services - R1Subject 2 Introduction to Refrigeration Systems v1.2 © 2004 Refrigeration Training Services No reproduction or unauthorized use allowed
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