R 1 Fundamentals of Refrigeration 2 Introduction to

R 1 Fundamentals of Refrigeration #2 Introduction to Refrigeration Systems © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2

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 - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 2

R 22 Elementary tank. Refrigerator inside Equilibrium 145 psig 80 80 Equilibrium © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 3

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: 1. Pressure in the tank? 2. Temperature of the refrigerant? 3. Temperature in the box? © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 4

Release Pressure Tank pressure falls Pressure R 22 temperature tankdrops, drops Pressure Drop 100 145 psig psg Vent outside box Box cools 80 70 80 60 Tank absorbs box heat Tank cools Refrigerant starts boiling 60 80 As pressure drops, temperature drops, box cools. © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 5

Refrigerant is too expensive to waste How can we recover the refrigerant? © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 6

Vapor captured in outside tank Vapor pressure rises with ambient R 22 tank 145 100 psig 60 80 Check valve 80 70 Vapor rises to ambient temperature © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 60 7

Changing vapor back to a liquid 1. Increase the vapor pressure Example: 100 psig to 225 psig 2. This increases the vapor‘s temperature Example: 80° to 110° 3. 80° ambient air is cooler than the vapor 4. The vapor condenses to a liquid © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 8

Increase pressure to condense vapor to liquid R 22 tank 225 145 psig 100 psig 80 110 Cooler ambient air condenses vapor to liquid 70 60 Increased pressure = increased temperature © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 9

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 - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 10

Return liquid to original tank R 22 tank 225 psig 100 psig 80 70 60 110 © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 11

Names for Components & Piping 1. Compressor Discharge line 2. Condenser Liquid line 3. Metering Device 4. Evaporator Suction line © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 12

Basic Components and Piping Discharge Line Compressor Suction Line Condenser Metering Device Liquid Line Evaporator © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 13

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 - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 14

Basic Components “Baseball Diamond” Metering Device Li qu id Li ne w de n Condenser Li ne ch a ct io H rg e Su h g i Si D is Evaporator Si e d Li ne Lo Compressor © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 15

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 - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 16

Simple A/C System AMBIENT AIR 95 o 165 o 278 psig 175 o 69 psig RETURN AIR 75 o 50 o 60 o 40 o 125 o 115 o 40 o 105 o 40 o © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 17

“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 - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 18

Standard A/C System R-22 69 psig 278 psig 175º 60º 40º 125º CONDENSER 125º EVAPORATOR 115º 40º 50º AMBIENT AIR 95 o RETURN AIR 75 o © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 19

Standard A/C System R-22 Total Superheat 20° 69 psig 278 psig Super Heated Vapor 175º 60º 40º 125º Evaporation Starts CONDENSER Condensing Starts EVAPORATOR 125º Fully Evaporated Fully Condensed Liquid Sub-Cooled Liquid AMBIENT AIR 95 o 115º 40º Coil Superheat 10° 50º RETURN AIR 75 o © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 20

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 - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 21

Typical Walk-In Refrigerator (R 22) 50 psig 280 psig 175º 45º 125º TEV CONDENSER 125º EVAPORATOR 115º 25º 35º AMBIENT AIR 95 o BOX TEMPERATURE 35 © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 22

Typical Walk-In Refrigerator (R 22) Total Superheat 20° 50 psig 280 psig Super Heated Vapor 175º 45º 25º 125º TEV Evaporation Starts CONDENSER Condensing Starts EVAPORATOR 125º Fully Evaporated Fully Condensed Liquid Sub-Cooled Liquid AMBIENT AIR 95 o 115º 25º Coil Superheat 10° 35º BOX TEMPERATURE 35 © 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 23

© 2004 Refrigeration Training Services - R 1 Subject 2 Introduction to Refrigeration Systems v 1. 2 24