thomas j kelly - iir · 2005-11-10 · 3. develop a ph diagram to use as a system analysis tool 4....
TRANSCRIPT
Job name:Fundamentals of Refrigeration
Page number:1
Thomas J KellySr. Engineering
Instructor
Carrier Corporation
August 20, 2003
Fundamentals of Refrigeration
Job name:Fundamentals of Refrigeration
Page number:2
SESSION OBJECTIVES
At the conclusion of this session you should be able to:1. Describe the basics principles of refrigeration systems
operation 2. Understand 10 common refrigeration terms3. Develop a PH diagram to use as a system analysis tool4. Use a PH diagram to describe basic system operation in
high temperature,medium temperature, low temperature and multi-stage refrigeration systems
5. Identify and place common system elements and components in the refrigeration system and understand their function in system operation
6. Understand basic system layouts associated with commercial store refrigeration
Job name:Fundamentals of Refrigeration
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COMFORT VS. PROCESSThe mechanical refrigeration process is used for two major types of market
ComfortCools and dehumidifies people
ProcessControls temperature and humidity for things
The basic process is the same
Job name:Fundamentals of Refrigeration
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THE REFRIGERATION MARKET CHAINFood products depend on refrigeration for processing, storage and delivery - At the point of harvest
- Warehousing
- Delivery to the market
- Market display and sale
- Consumer storage
Job name:Fundamentals of Refrigeration
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Sub-coolingSuperheat
Refrigeration Effect
Enthalpy
Vapor Quality
Flash Gas
What is he talking about ?
High Side / Low Side
Saturated Suction
Heat of CompressionHeat of Rejection
PH diagram
Latent Heat
Expansion DeviceRefrigeration Effect
Sensible Heat
Throttling Range
REFRIGERATION TERMS
Job name:Fundamentals of Refrigeration
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BASIC SYSTEM COMPONENTSEvery system has 4 basic components
Evaporator
Absorbs the heat from the air or load
Air in: 80F DB / 67F WB
Air out: 59.7F DB / 57.3F WB
EVAPORATOR
59 F
78 PSI
47 F
78 PSI
ColdMixture
ColdVapor
Job name:Fundamentals of Refrigeration
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BASIC SYSTEM COMPONENTSEvery system has 4 basic components
Evaporator
Compressor
Raises the pressure from the evaporator pressure to the condensing temperature
Air in: 80F DB / 67F WB
Air out: 59.7F DB / 57.3F WB
EVAPORATOR
59 F
78 PSI
47 F
78 PSI
COMPRESSOR
220 F
175PSI
ColdVapor
HotVapor
Job name:Fundamentals of Refrigeration
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BASIC SYSTEM COMPONENTSEvery system has 4 basic components
Evaporator
Compressor
Condenser
Rejects the heat from the load and system losses
Air in: 80F DB / 67F WB
Air out: 59.7F DB / 57.3F WB
EVAPORATOR
59 F
78 PSI
47 F
78 PSI
CONDENSER
Air in: 95F DB
Air out: 95F DB
COMPRESSOR
220 F
175PSI
110 F
175PSI
HotLiquid
Hot Vapor
Job name:Fundamentals of Refrigeration
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BASIC SYSTEM COMPONENTSEvery system has 4 basic components
Evaporator
Compressor
Condenser
Metering deviceRegulates the flow and decreases the pressure from condensing pressure to evaporator pressure
METERING DEVICE
Air in: 80F DB / 67F WB
Air out: 59.7F DB / 57.3F WB
EVAPORATOR
59 F
78 PSI
47 F
78 PSI
CONDENSER
Air in: 95F DB
Air out: 95F DB
COMPRESSOR
220 F
175PSI
110 F
175PSI
Cold Mixture
HotLiquid
Job name:Fundamentals of Refrigeration
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BASIC SYSTEM COMPONENTS
High Side
Compressor discharge to Metering device
Low Side
Metering device to Compressor suction
METERING DEVICE
EVAPORATOR
CONDENSER
COMPRESSOR
High Side
Low Side
Job name:Fundamentals of Refrigeration
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4 LAW OF SYSTEM OPERATION1. Heat only moves from higher
temperature to a lower temperature
212º
70º
FLOW
70º 70ºNO FLOW
70º
32º
FLOW
Job name:Fundamentals of Refrigeration
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4 LAW OF SYSTEM OPERATION1. Heat only moves from higher
temperature to a lower temperature
2. Energy required to change of states of matter is large
1 BTU / LB
70 º F
71 º F
Sensible Heat
Job name:Fundamentals of Refrigeration
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4 LAW OF SYSTEM OPERATION1. Heat only moves from higher
temperature to a lower temperature
2. Energy required to change of states of matter is large
970 BTU / LB
SATURATEDVAPOR212ºF
212 º F
Latent Heat
Job name:Fundamentals of Refrigeration
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4 LAW OF SYSTEM OPERATION1. Heat only moves from higher
temperature to a lower temperature
2. Energy required to change of states of matter is large
3. The temperature and energy required to change state are a function of pressure
190º F
5 PSI
9 PSIA
230º F
Job name:Fundamentals of Refrigeration
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4 LAW OF SYSTEM OPERATION1. Heat only moves from higher
temperature to a lower temperature
2. Energy required to change of states of matter is large
3. The temperature and energy required to change state are a function of pressure
4. Fluid flow only occurs if a pressure difference exists
5 PSI
0 PSI
Job name:Fundamentals of Refrigeration
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TEMPERATURE – ENTHALPY PLOTR 718 ( Water) as an example
TEM
PER
ATU
RE
ºF
Enthalpy is the total heat content
Enthalpy = Sensible + Latent
Enthalpy(Btu/lb)
32
212
256
0
Job name:Fundamentals of Refrigeration
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TEMPERATURE – ENTHALPY PLOTR 718 ( Water) as an example 1 pound at standard barometric pressure
TEM
PER
ATU
RE
ºF
Enthalpy(Btu/lb)
32
0Sub-cooled Solid
16
ICE
160
Latent heat of Fusion
212
LIQUID
144 Btu/lb
Job name:Fundamentals of Refrigeration
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TEMPERATURE – ENTHALPY PLOTR 718 ( Water) as an example 1 pound at standard barometric pressure
TEM
PER
ATU
RE
ºF
Enthalpy(Btu/lb)
32
016
ICE
160
Latent heat of
Vaporization
Condensation
212
256
LIQUID
VAPO
R
340 1310 1320
1 Btu/lb 970 Btu/lb 0.45 Btu/lb
Sub-cooled Liquid
Superheated Vapor
Job name:Fundamentals of Refrigeration
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TEMPERATURE – ENTHALPY PLOTR 718 ( Water) as an example 1 pound at standard barometric pressure
TEM
PER
ATU
RE
ºF
Enthalpy(Btu/lb)
32
016
ICE
160
212
256
LIQUID
VAPO
R
340 1310 1320
1 Btu/lb 970 Btu/lb 0.45 Btu/lb
Sub-cooled Liquid
Superheated Vapor
100% Saturated
Liquid
100% Saturated
Liquid
Job name:Fundamentals of Refrigeration
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P H DIAGRAMPlots enthalpy vs. pressure
Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
P1
P2
P3
P4
P5
P6
P7
P8
P9
P10
Saturated Liquid
Saturated Vapor
Critical Point
Job name:Fundamentals of Refrigeration
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P H DIAGRAMTake note the lines become closer at higher pressure – less latent capacity
Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
P1
P2
14.7
P4
P5
P6
P7
P9
P10 Critical Point
422
775 Btu/lb
970 Btu/lbSaturated
LiquidSaturated
Vapor
Job name:Fundamentals of Refrigeration
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P H DIAGRAMVapor Quality is percentage of the mixture
Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
P1
P2
P3
P4
P5
P6
P7
P9
P10
Sub-cooled Liquid
Superheated Vapor
Critical Point
P8 20
Vapor Quality
40 60 80
Job name:Fundamentals of Refrigeration
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P H DIAGRAMRefrigerant Blends
Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
P1
P2
P3
P4
P5
P6
P7
P9
P10
Sub-cooled Liquid
Superheated Vapor
Critical Point
P8
Vapor Quality
Blends
Bubb
le P
oint
Dew
Poi
nt
Job name:Fundamentals of Refrigeration
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P H DIAGRAMTemperature Lines
Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
P1
14.7
P10
212 ºF
450 ºF422
TEMPERATURE
Job name:Fundamentals of Refrigeration
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P H DIAGRAMEntropy Lines
Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
P1
14.7
422
P10 451
Btu/ºR
450
Btu/ºR
ENTROPY
Job name:Fundamentals of Refrigeration
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P H DIAGRAMSpecific Volume Lines
Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
P1
14.7
422
P10
1.1 ft3/lb
26.8 ft3/lb
SPECIFIC VOLUME
Job name:Fundamentals of Refrigeration
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SATURATED LIQUID
SATURATED VAPOR
SATURATED MIXTURE
SUBCOOLED LIQUID
SUPERHEATED VAPOR
P H DIAGRAMP H DIAGRAM
Time to test your skill
Job name:Fundamentals of Refrigeration
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0 20 40 60 80 90 100 110 120 130 140 150-20Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
R-22
20 - 30
38 057 20
147 70
300 125225 105
91 45
PH DIAGRAM FOR R-22
TEMPERATUREENTROPY
SPECIFIC VOLUME
Job name:Fundamentals of Refrigeration
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20 - 30
38 057 20
147 70
300 125225 105
91 45
0 20 40 60 80 90 100 110 120 130 140 150-20Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
R-22
BASIC SYSTEM ON THE PH DIAGRAM
EVAPORATOR
COMPRESSOR
CONDENSEREXPANSION
DEVICE
Job name:Fundamentals of Refrigeration
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EVAPORATOR TYPES
Air cooled
Water cooled (cooler)
Job name:Fundamentals of Refrigeration
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EvaporationSuperheat
ColdMixed Phase
Saturated Vapor ColdSuperheated Vapor
EVAPORATOR PROCESSTwo processes 1. Evaporation – change the mixture of gas and liquid refrigerant to all
vapor2. Superheating – Increase temperature above saturated suction
Superheat is required to assure vapor at the compressorBut has negative impact on total system efficiency
Job name:Fundamentals of Refrigeration
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EVAPORATOR OPERATION
Air in: 80F DB / 67F WB
Air out: 59.7F DB / 57.3F WB
EVAPORATOR
59 F78 PSI
47 F78 PSI
Flash Gas - Vapor quality entering evaporator
Refrigeration Effect –Total heat absorbed by evaporator
Refrigeration Effect
ColdMixed Phase47F - 78PSI
ColdSuperheated Vapor
59F � 78PSIFlash Gas
Job name:Fundamentals of Refrigeration
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COMPRESSOR TYPESReciprocating
Scroll
Screw
Rotary
Centrifugal
Job name:Fundamentals of Refrigeration
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One process 1. Raise the pressure of the superheated gas from saturated suction
temperature to a pressure which corresponds to saturated condensing- Decreases the volume – Increases the pressure – Increases the temperature - The compression process adds considerably more superheat
CompressionSaturated Vapor
Cold Superheated Vapor
Hot Superheated Vapor
COMPRESSOR PROCESS
Job name:Fundamentals of Refrigeration
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COMPRESSSOR OPERATION
Heat of Compression –Heat added from the compression process
Compression Ratio –Discharge pressure / suction pressure EVAPORATOR
50 F55PSI
COMPRESSOR
220 F
175PSI
Heat of Compression ColdSuperheated Vapor
59F � 78PSI
Compression
Hot Superheated Vapor
220F � 175PSI
Compression Ratio
Job name:Fundamentals of Refrigeration
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ROTARY COMPRESSORS
Used in :Small AC unitsAppliances
Uses rotating piston and a sliding vane
Job name:Fundamentals of Refrigeration
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RECIPROCATING COMPRESSORS
Used in :AC, Refrigeration & Appliances
Uses reciprocating piston and reed valves
Job name:Fundamentals of Refrigeration
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SCROLL COMPRESSOR
Used in :AC, Refrigeration & Appliances
Uses a stationary scroll and a rotating scroll and has no valves
Job name:Fundamentals of Refrigeration
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SCREW COMPRESSOR
Used in :AC & Refrigeration
Uses a stationary screw and a rotating screw and a slide valve
Job name:Fundamentals of Refrigeration
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CONDENSER TYPESAir cooled
Water cooled
Job name:Fundamentals of Refrigeration
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Three processes 1. De-Superheating � Lower temperature to saturated condensing temp.2. Condensing � Condense vapor to liquid3. Sub-cool the liquid below saturated condensing temperature, sub-cooling:
- Is required to assure liquid at the expansion device- Has positive impact on total system efficiency
Condensing
Saturated Vapor
Hot Superheated Vapor
220F 175PSI
CONDENSER PROCESS
De-superheatingHotSub-cooled Liquid
110F 175PSI
Sub-cooling
Job name:Fundamentals of Refrigeration
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Heat of Rejection
Hot Sub-cooled Liquid
Hot Superheated Vapor
EVAPORATOR COMPRESSOR
220 F
175PSI
CONDENSER
Air in: 95F DB
Air out: 95F DB
110 F
175PSI
CONDENSER OPERATION
Heat of Rejection –Refrigerant effect plus heat of compression
Job name:Fundamentals of Refrigeration
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EXPANSION DEVICES TYPESFixed Metering
TXV
Floats
Job name:Fundamentals of Refrigeration
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Two processes 1. Create a pressure drop – Decreasing the temperature below
saturated suction, Flashing part of the liquid into vapor to cool the mixture of vapor and liquid to saturated suction temperature
2. Meter the flow of refrigerant
EXPANSION DEVICE PROCESS
Expansion Device
HotSub-cooled Liquid
110F 175PSI
ColdMixed Phase47F 70PSI
Job name:Fundamentals of Refrigeration
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EXPANSION DEVICE OPERATION
Throttling Range
Hot Sub-cooled Liquid
Throttling Range –Pressure drop available across the metering device
Expansion Device
HotSub-cooled Liquid
110F 175PSI
ColdMixed Phase47F 70PSI
EVAPORATOR COMPRESSOR
CONDENSER110 F
175PSI
METERING DEVICE
47 F
78 PSI
Job name:Fundamentals of Refrigeration
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PH DIAGRAM - SYSTEM INEFFICIENCIES
Evaporator Coil ∆P
Condenser Coil ∆P
Suction Line ∆P
Discharge Line ∆P
LiquidLine ∆P
Job name:Fundamentals of Refrigeration
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20 - 30
38 057 20
147 70225 105
0 20 40 60 80 90 100 110 120 130 140 150-20
300 125
R-22
R-134
91 45
PRES
SUR
E PS
IA
Enthalpy(Btu/lb)
0
- 30
20
45
70105
125
P H DIAGRAM FOR R-134A REFRIGERANT
Job name:Fundamentals of Refrigeration
Page number:48
20
38
57
147 70225
0 20 40 60 80 90 100 110 120 130 140 150-20
300125
R-22
R-134
91 45
PRES
SUR
E PS
IA
Enthalpy(Btu/lb)
45
125
R-22 VS. R-134A REFRIGERANT CYCLE
Job name:Fundamentals of Refrigeration
Page number:49
20 - 30
38 057 20
147 70225 105
0 20 40 60 80 90 100 110 120 130 140 150-20
300 125
R-22
R-404
91 45
PRES
SUR
E PS
IA
Enthalpy(Btu/lb)
0
- 30
20
45
70105
125
P H DIAGRAM FOR R-404 REFRIGERANT
Job name:Fundamentals of Refrigeration
Page number:50
20
38
57
147225
0 20 40 60 80 90 100 110 120 130 140 150-20
300125
R-22
R-404
91 45
PRES
SUR
E PS
IA
Enthalpy(Btu/lb)
70
125
R-22 VS. R-404 REFRIGERANT CYCLE
Job name:Fundamentals of Refrigeration
Page number:51
THE BASIC REFRIGERATION SYSTEM
Basic Refrigeration SystemSame system with a few special features
Basic System
COMPRESSOR
EVAPORATOR
CONDENSER
EXPANSION VALVE
RECIEVER
LIQUID LINE DRIER
MOISTURE LIQUID INDICATOR
SUCTION ACCUMULATOR
Job name:Fundamentals of Refrigeration
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91 45
293 125
Enthalpy(Btu/lb)
PRES
SUR
E PS
IAPH DIAGRAM - HIGH TEMPERATURE
0 20 40 60 80 90 100 110 120 130 140 150-20
400
200140100
60
40
20
10
RE = 67 BTU/#
TR=202 PSITXV
R-22
EVAPORATOR
COMPRESSORCR=3.2
THR = 81 BTU/#CONDENSER
Job name:Fundamentals of Refrigeration
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REFRIGERATION SYSTEM TYPESSelf Contained
Condensing units
Rack systems
Job name:Fundamentals of Refrigeration
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WALK-IN COOLER MEDIUM TEMP RACK
LOW TEMP RACK
AIR COOLED CONDENSER
WALK-IN FREEZER
MULTI DECK DELI/DAIRY
MEAT-DELI
SINGLE DECK MEAT DISPLAY
FROZEN FOOD
REACH IN FROZEN FOOD
TYPICAL LARGER MARKET LAYOUT
Job name:Fundamentals of Refrigeration
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MULTI DECK DELI/DAIRY
WALK-IN COOLER MEDIUM/LOW TEMP RACK
AIR COOLED CONDENSER
FROZEN FOODS
MEAT/DELI
TYPICAL SMALLER MARKET LAYOUT
Job name:Fundamentals of Refrigeration
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MED TEMP COND UNIT
LOW
MED
MULTI DECK DELI/DAIRY
FROZEN FOODS
MEAT/DELI
CONVENIENCE STORE LAYOUT
Job name:Fundamentals of Refrigeration
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MEDIUM TEMPERATURE REFRIGERATION Typical Cases 15F to 35F PRODUCE AND DELI
COMPRESSOR
EVAPORATOR
CONDENSER
EXPANSION VALVE
RECIEVER
LIQUID LINE DRIER
MOISTURE LIQUID INDICATOR
SUCTION ACCUMULATOR
Job name:Fundamentals of Refrigeration
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57 20
293 125
Enthalpy(Btu/lb)
PRES
SUR
E PS
IAPH DIAGRAM - MEDIUM TEMPERATURE
0 20 40 60 80 90 100 110 120 130 140 150-20
400
200140100
60
40
20
10
RE = 70 BTU/#
TR=236 PSI
TXV
R-22
EVAPORATOR
COMPRESSOR
CR=5.1
THR = 94 BTU/#CONDENSER
Job name:Fundamentals of Refrigeration
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LOW TEMPERATURE REFRIGERATION Typical Cases -15F to -30F FROZEN FOOD AND ICE CREAM
COMPRESSOR
EVAPORATOR
CONDENSER
EXPANSION VALVE
RECIEVER
LIQUID LINE DRIER
MOISTURE LIQUID INDICATOR
SUCTION ACCUMULATOR
Job name:Fundamentals of Refrigeration
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17 -30
293 125
Enthalpy(Btu/lb)
PRES
SUR
E PS
IAPH DIAGRAM - LOW TEMPERATURE
0 20 40 60 80 90 100 110 120 130 140 150-20
400
200140100
60
40
20
10
RE = 63 BTU/#
TR=276 PSI
TXV
R-22
EVAPORATOR
COMPRESSORCR=17.2
THR = 96 BTU/#CONDENSER
Job name:Fundamentals of Refrigeration
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REFRIGERATION EVAPORATORSCases
ProduceAir SST
+33F 20FIce CreamAir SST
-25F -35FFrozen Food
Air SST-15F -25F
MeatAir SST27F 15F
DairyAir SST25F 15F
Job name:Fundamentals of Refrigeration
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REFRIGERATION EVAPORATORSUnit Coolers
Reach in
Walk In
Blast freezers
Job name:Fundamentals of Refrigeration
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EVAPORATOR DEFROSTAir Defrost
Electric Defrost
Hot GasReverse Cycle
Three pipe
Drain pan heaters
Job name:Fundamentals of Refrigeration
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DEFROST DIFFERENTIAL VALVESDefrost with Differential Regulating Valve
Liquid line
Discharge Line
Job name:Fundamentals of Refrigeration
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DEFROST DIFFERENTIAL VALVESDefrost with Differential Regulating Valve
COMPRESSOR
EVAPORATOR
CONDENSER
EXPANSION VALVE
RECIEVER
LIQUID LINE DRIER
MOISTURE LIQUID INDICATOR
SUCTION ACCUMULATOR
EVAPORATOR PRESSURE
REGULATOR
LIQUID DIFFERENTIAL VALVE
DISCHARGE DIFFERENTIAL
VALVEEVAPORATOR
SOLENOID VALVE
SOLENOID VALVE
SOLENOID VALVE
CHECK VALVE
Job name:Fundamentals of Refrigeration
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Evaporator Pressure Regulators
Maintains constant pressure in the evaporator
Job name:Fundamentals of Refrigeration
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Evaporator Pressure Regulators
COMPRESSOR
EVAPORATOR
CONDENSER
EXPANSION VALVE
RECIEVER
LIQUID LINE DRIER
MOISTURE LIQUID INDICATOR
SUCTION ACCUMULATOR
EVAPORATOR PRESSURE
REGULATOR
Job name:Fundamentals of Refrigeration
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Receiver
Common Suction Header 10°F 44 psig
15°F15°F
20°F20°F
Multiple Evaporator systems with common suction
Maintains stable evaporator pressure to control temperature
Evaporator Pressure Regulator
Job name:Fundamentals of Refrigeration
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PH DIAGRAM – MULTIPLE EVAPORATORS
140
60
40
17 -30
293 125
Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
400
200
100
20
10
TXV
R-22
COMPRESSOR
CONDENSER
57 20
0 20 40 60 80 90 100 110 120 130 140 150-20
LOW STAGE
MEDIUM STAGE
0 20 40 60 80 90 100 110 120 130 140 150-20
EVAPORATOR
Job name:Fundamentals of Refrigeration
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SUCTION ACCUMULATORProtects the compressor from liquid
Separates vapor from liquid
Provides for oil return
Oil ReturnOrifice
Fusible Plug
IN
Job name:Fundamentals of Refrigeration
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RECIEVERSProvide storage volume for excess refrigerant
Pump down storage
Job name:Fundamentals of Refrigeration
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REFRIGERATION COMPRESSORSSelf Contained
Condensing Units
Rack Systems
Job name:Fundamentals of Refrigeration
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REFRIGERATION COMPRESSORSScroll
1 to 15 HPRefrigeration duty differences
Vapor InjectionLiquid Injection
ApplicationsSelf containedCondensing unitsRack systems
Job name:Fundamentals of Refrigeration
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REFRIGERATION COMPRESSORS
40
140
60
17 -30
293 125
Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
400
200
100
20
10
TXV
R-22
COMPRESSOR
CONDENSER
57 20
0 20 40 60 80 90 100 110 120 130 140 150-20
LOW STAGE
INJECTION
0 20 40 60 80 90 100 110 120 130 140 150-20
EVAPORATOR
GAIN
Job name:Fundamentals of Refrigeration
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REFRIGERATION COMPRESSORSReciprocating Hermetic
1 to 5 HPRefrigeration duty differences
ApplicationsSelf containedCondensing unitsRack systems
Job name:Fundamentals of Refrigeration
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REFRIGERATION COMPRESSORSReciprocating Semi-Hermetic
3 to 60 HPRefrigeration duty differences
Cooling fans
Compound cooling
ApplicationsStand aloneCondensing unitsRack systems
Job name:Fundamentals of Refrigeration
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REFRIGERATION COMPRESSORSReciprocating Semi-Hermetic
Typical low temperature
De-superheating valve
Job name:Fundamentals of Refrigeration
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COMPOUND COMPRESSORSSingle compressor
Multiple compressor
Job name:Fundamentals of Refrigeration
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COMPOUND COOLING
40
140
60
17 -30
293 125
Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
400
200
100
20
10
TXV
R-22
COMPRESSOR
CONDENSER
57 20
0 20 40 60 80 90 100 110 120 130 140 150-20
LOW STAGE
MEDIUM STAGE
0 20 40 60 80 90 100 110 120 130 140 150-20
EVAPORATOR
Job name:Fundamentals of Refrigeration
Page number:80
REFRIGERATION COMPRESSORSScrew Compressor
20 to 140 HPRefrigeration duty differences
Oil control systemLiquid injection
ApplicationsCondensing unitsRack systemsBuilt up system
Job name:Fundamentals of Refrigeration
Page number:81
Prevents over-pressurization of Two-Stage Compressor crankcase. Crankcase Pressure Regulator
40
140
60
17 -30
293 125
Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
400
200
100
20
10
TXV
R-22
COMPRESSOR
CONDENSER
57 20
0 20 40 60 80 90 100 110 120 130 140 150-20
LOW STAGE
MEDIUM STAGE
0 20 40 60 80 90 100 110 120 130 140 150-20
EVAPORATOR
Job name:Fundamentals of Refrigeration
Page number:82
Crankcase Pressure Regulator
On two-stage compressors systems and Low Temperature -- Compression Ratio > 10:1Discharge of One Cylinder is De-Superheated and Used as Suction for Another Cylinder to Limit the Heat of Compression.
Results:Excessively High Suction Pressures after-Pull-Down or Defrost Cycles, can Cause Motor Overload.
Job name:Fundamentals of Refrigeration
Page number:83
CAPACITY CONTROL
Why?• Prevent the Compressor from Short Cycling• Prevent Compressor from Operating with Too
Low Suction Pressures• Prevent Evaporating Coil Icing
OPTIONS:1. Multiple Units2. Single Units with Multiple
Compressors.3. Variable Speed Compressors4. Compressor Cylinder Unloading5. Hot Gas Bypass
Job name:Fundamentals of Refrigeration
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CAPACITY CONTROL
1. Multiple Units2. Single Units with
Multiple Compressors.
3. Variable Speed Compressors
Job name:Fundamentals of Refrigeration
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CAPACITY CONTROL
4. Compressor Cylinder Unloading
Job name:Fundamentals of Refrigeration
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HOT GAS BYPASS CONTROL
COMPRESSOR
EVAPORATOR
CONDENSER
EXPANSION VALVE
RECIEVER
LIQUID LINE DRIER
MOISTURE LIQUID INDICATOR
SUCTION ACCUMULATOR
EVAPORATOR PRESSURE
REGULATOR
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Hot Gas Bypass Regulators
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Bypasses High Pressure Refrigerant to the System’s Low Pressure Side. Regulates to Maintain a Set Minimum Suction Pressure.
Hot Gas Bypass
Bypass to Suction
De-Superheating TXV
Bypass to Evaporator Inlet
Job name:Fundamentals of Refrigeration
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UPSTREAM OF UPSTREAM OF ACCUMULATORACCUMULATOR
LIQUID INJECTIONTHERMO VALVE
LIQUID INJECTIONSOLENOID VALVE
BYPASS REGULATOR
BYPASS SOLENOID
SUCTIONACCUMULATOR
SUCTION
BYPASS TO SUCTION WITH SUCTION ACCUMULATOR
Job name:Fundamentals of Refrigeration
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UPSTREAM OF UPSTREAM OF ACCUMULATORACCUMULATOR
LIQUID INJECTIONTHERMO VALVE
LIQUID INJECTIONSOLENOID VALVE
BYPASS REGULATOR
BYPASS SOLENOID
SUCTION
OUTLET OF OUTLET OF ACCUMULATORACCUMULATOR
* IF A BOILOUT ACCUMULATOR IS USED, LOCATE LCL BULB UPSTREAM
BYPASS TO SUCTION WITH SUCTION ACCUMULATOR
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LIQUID INJECTIONTHERMO VALVE
LIQUID INJECTIONSOLENOID VALVE
BYPASS REGULATOR
BYPASS SOLENOID
SUCTIONACCUMULATOR
SUCTION
Constant headpressure is required during periods of bypass.
BYPASS TO SUCTION WITH SUCTION ACCUMULATOR
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BYPASS SOLENOID DIRECT ACTINGBYPASS
REGULATOR
BYPASS TO EVAPORATOR INLET
EVAPORATOR
COMPRESSOR
THERMO VALVE
LIQUID LINESOLENOID
VALVE
ADVANTAGES:• Provides a False Load• Defrost the Coil, A/C• Evaporator serves as
mixing chamber• Minimizes components• Excellent Oil Return
BYPASS TO EVAPORATOR INLET
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BYPASS TO EVAPORATOR INLET
COMPRESSOR
EVAPORATOR
THERMO VALVE
LIQUID LINESOLENOID
VALVE
BYPASS SOLENOID
DIRECT ACTINGBYPASS
REGULATOR
With the evaporator BELOW the compressor,bypass to evaporator inletassures proper oil returnat low loads.
BYPASS TO EVAPORATOR INLET
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REFRIGERATION CONDENSERSAir Cooled
Water Cooled
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Why?•Maintain Liquid Sub-Cooling and Prevent liquid line flash gas.•Provide sufficient pressure drop across TXV.•Properly operate systems with hot gas defrost, hot gas bypass or heat reclaim systems.
How?hVariable Condenser Fan Speed ControlhWater regulating valvehCondenser Fan Cycling hVane / Damper Control SystemhSplit Condenser Systemh“Flooded” Head Pressure Control
Head Pressure ControlHead Pressure Control
Job name:Fundamentals of Refrigeration
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Fan Cycling200
150
HEA
D P
RES
SUR
E
TIME
Fan off
Fan on
Head Pressure ControlAir Cooled Units
Job name:Fundamentals of Refrigeration
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Variable Speed Fan
Head Pressure ControlAir Cooled Units
Water Cooled UnitsWater regulating Valve
Job name:Fundamentals of Refrigeration
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CONSTANT LOAD AT REDUCED CONDENSING TEMPERATURE
HEAD PRESSURE CONTROL
40
140
60
17 -30
293 125
Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
400
200
100
20
10
TXV
R-22
COMPRESSOR
CONDENSER
57 20
0 20 40 60 80 90 100 110 120 130 140 150-20
LOW STAGE
MEDIUM STAGE
0 20 40 60 80 90 100 110 120 130 140 150-20
EVAPORATOR
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CONDENSER HEAD PRESSURE CONTROL
EVAPORATOR TEMPERATURE
CONTROL
EVAPORATOR PRESSURE
REGULATOR
SUCTION FILTER -DRIER
LOW PRESSURE CONTROL
OIL PRESSURE SAFETY
CONTROL
CONDENSER TEMPERATURE
CONTROL
FAN CYCLING CONTROL
OIL SEPERATOR
OIL FILTER
OIL LEVEL CONTROL
SOLENOID VALVE
HOT GAS BYPASS
REGULATOR
BALL VALVE
COMPRESSOR
EVAPORATORCONDENSER
EXPANSION VALVE
RECIEVER
LIQUID LINE DRIER
MOISTURE LIQUID INDICATOR
SUCTION ACCUMULATOR
SOLENOID VALVE
HIGH -LOW PRESSURE CONTROL
HEAD PRESSURE CONTROL VALVE
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“Flooded” Condenser
Condenser Outlet
Receiver
Condenser Bypass
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FLOODED CONDENSER CONTROL
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METERING DEVICES IN REFRIGERATIONExpansion Valves--Equalizer-Constant pressure valves
Hand Valves
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OPR
Outlet Pressure regulatorsManual
Adjustment
Regulated Outlet
Pressure
Inlet Pressure
Job name:Fundamentals of Refrigeration
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IPR
Inlet Pressure RegulatorsManual Adjustment
Regulated Inlet
Pressure
Outlet Pressure
Job name:Fundamentals of Refrigeration
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DESUPERHEATERSReduce compressor superheat
40
140
60
17 -30
293 125
Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
400
200
100
20
10
TXV
R-22
COMPRESSOR
CONDENSER
57 20
0 20 40 60 80 90 100 110 120 130 140 150-20
LOW STAGE
DE-SUPERHEATER
0 20 40 60 80 90 100 110 120 130 140 150-20
EVAPORATOR
Job name:Fundamentals of Refrigeration
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REFRIGERATION SYSTEM VALVESControl Isolation
EVAPORATOR TEMPERATURE
CONTROL
EVAPORATOR PRESSURE
REGULATOR
SUCTION FILTER -DRIER
LOW PRESSURE CONTROL
OIL PRESSURE SAFETY
CONTROL
CONDENSER TEMPERATURE
CONTROL
FAN CYCLING CONTROL
OIL SEPERATOR
OIL FILTER
OIL LEVEL CONTROL
SOLENOID VALVE
HOT GAS BYPASS
REGULATOR
BALL VALVE
COMPRESSOR
EVAPORATORCONDENSER
EXPANSION VALVE
RECIEVER
LIQUID LINE DRIER
MOISTURE LIQUID INDICATOR
SUCTION ACCUMULATOR
SOLENOID VALVE
HIGH -LOW PRESSURE CONTROL
Job name:Fundamentals of Refrigeration
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SOLENOIDS VALVESProvide Control Function- On / Off Control - Normally Open / Normally closed
Used-Pump down-Circuit isolation-Hot Gas isolation-Defrost Isolation
Job name:Fundamentals of Refrigeration
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Ball ValvesDiaphragm ValvesPacked Angle ValvesGlobe ValvesPressure Relief Valves
- Condensers- Pressure Vessels
Check Valves
REFRIGERATION VALVES
Job name:Fundamentals of Refrigeration
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REFRIGERATION SYSTEM PROTECTORSMoisture Liquid IndicatorsFilter Driers
COMPRESSOR
EVAPORATORCONDENSER
EXPANSION VALVE
RECIEVER
LIQUID LINE DRIER
MOISTURE LIQUID INDICATOR
SUCTION ACCUMULATOR
EVAPORATOR TEMPERATURE
CONTROL
EVAPORATOR PRESSURE
REGULATOR
SUCTION FILTER -DRIER
LOW PRESSURE CONTROL
OIL PRESSURE SAFETY
CONTROL
CONDENSER TEMPERATURE
CONTROL
FAN CYCLING CONTROL
OIL SEPERATOR
OIL FILTEROIL LEVEL CONTROL
SOLENOID VALVE
SOLENOID VALVE
HOT GAS BYPASS
REGULATOR
BALL VALVE
HIGH -LOW PRESSURE CONTROL
Job name:Fundamentals of Refrigeration
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SIGHT GLASSES MOISTURE INDICATORS
Provide an indication of refrigerant flow & moisture content
Provide an indication of system charge
Locations :
Liquid line
- Between liquid line filter-drier outlet & TXV inlet
Oil Line
- On oil separator or reservoir outlet
Job name:Fundamentals of Refrigeration
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LIQUID LINE FILTER - DRIERRemoves contaminants and chemical reaction products
Filter-Driers removeParticles WaterAcidsRemoves Solid and Sludge
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SUCTION LINE FILTER - DRIERSuction line filter - Driers
Job name:Fundamentals of Refrigeration
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OIL CONTROL SYSTEMSOil system controls
COMPRESSOR
EVAPORATORCONDENSER
EXPANSION VALVE
RECIEVER
LIQUID LINE DRIER
MOISTURE LIQUID INDICATOR
SUCTION ACCUMULATOR
EVAPORATOR TEMPERATURE
CONTROL
EVAPORATOR PRESSURE
REGULATOR
SUCTION FILTER -DRIER
LOW PRESSURE CONTROL
OIL PRESSURE SAFETY
CONTROL
CONDENSER TEMPERATURE
CONTROL
FAN CYCLING CONTROL
OIL SEPERATOR
OIL FILTEROIL LEVEL CONTROL
SOLENOID VALVE
SOLENOID VALVE
HOT GAS BYPASS
REGULATOR
BALL VALVE
HIGH -LOW PRESSURE CONTROL
Job name:Fundamentals of Refrigeration
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OIL CONTROL SYSTEMSPROTECTS THE COMPRESSORS TO CONTROL PROPER OIL LEVEL
SYSTEM-Oil level control-Oil separator-Oil sight glass-Oil line filter-Oil reservoir-Check valve
OIL LINE FILTER
OIL RESERVOIR
SUCTION HEADER
OIL LEVEL CONTROL
OIL SEPARATOR
DISCHARGE HEADER
TO CONDENSER
CHECK VALVE
Job name:Fundamentals of Refrigeration
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OIL CONTROL SYSTEMSLow Pressure Oil Management System
High Pressure Oil Management System
SYSTEM-Oil level control-Oil separator-Oil sight glass-Oil line filter-Oil reservoir-Check valve
SUCTION HEADER
OIL LEVEL CONTROLOIL SEPARATOR
RESERVOIR
OIL LINE FILTER
DISCHARGE HEADER
TO CONDENSER
OIL LINE FILTER
OIL RESERVOIR
SUCTION HEADER
OIL LEVEL CONTROL
OIL SEPARATOR
DISCHARGE HEADER
TO CONDENSER
CHECK VALVE
Job name:Fundamentals of Refrigeration
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TEMPERATURE & PRESSURE CONTROLSTemperature ControlsPressure Controls
COMPRESSOR
EVAPORATORCONDENSER
EXPANSION VALVE
RECIEVER
LIQUID LINE DRIER
MOISTURE LIQUID INDICATOR
SUCTION ACCUMULATOR
EVAPORATOR TEMPERATURE
CONTROL
EVAPORATOR PRESSURE
REGULATOR
SUCTION FILTER -DRIER
LOW PRESSURE CONTROL
OIL PRESSURE SAFETY
CONTROL
CONDENSER TEMPERATURE
CONTROL
FAN CYCLING CONTROL
OIL SEPERATOR
OIL FILTEROIL LEVEL CONTROL
SOLENOID VALVE
SOLENOID VALVE
HOT GAS BYPASS
REGULATOR
BALL VALVE
HIGH -LOW PRESSURE CONTROL
Job name:Fundamentals of Refrigeration
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TEMPERATURE CONTROL APPLICATIONS
Evaporator temperature sensingDischarge air temperature sensingProduct temperature sensingReturn air temperature sensingEvaporator coil freeze protectionDefrost termination
Job name:Fundamentals of Refrigeration
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PRESSURE CONTROL APPLICATIONSLow Pressure Controls- Temperature control- Pump down control- High Temperature
alarm- Defrost termination- Low pressure limit /
alarm- Capacity controlHigh Pressure Controls- High pressure cut-out- High pressure alarm- Condenser head
pressure controlOil Pressure Controls- Oil pressure safety
Job name:Fundamentals of Refrigeration
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ECONOMIZER CYCLE
40
140
60
17 -30
293 125
Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
400
200
100
20
10
TXV
R-22
COMPRESSOR
CONDENSER
57 20
0 20 40 60 80 90 100 110 120 130 140 150-20
LOW STAGE
ECONOMIZER
0 20 40 60 80 90 100 110 120 130 140 150-20
EVAPORATOR
Improving Stage efficiency
Job name:Fundamentals of Refrigeration
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HEAT RECLAIM SYSTEMSRecovery of Condenser heat for space heating
COMPRESSOR
EVAPORATORCONDENSER
EXPANSION VALVE
RECIEVER
LIQUID LINE DRIER
MOISTURE LIQUID
INDICATOR
SUCTION ACCUMULATOR
EVAPORATOR PRESSURE
REGULATOR
LIQUID DIFFERENTIAL
VALVE
DISCHARGE DIFFERENTIAL
VALVEEVAPORATOR
SOLENOID VALVE
SOLENOID VALVE
SOLENOID VALVE CHECK
VALVE
HEAT RECLAIM
COIL
HEAT RECLAIM
VALVE
Job name:Fundamentals of Refrigeration
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SYSTEM TYPESDirectRefrigerant runs
directly to cases
IndirectSecondary cooling
circuit is used
Job name:Fundamentals of Refrigeration
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Practice Example PH chart example, Let�s look at a refrigeration example and plot a low temperature system
Job name:Fundamentals of Refrigeration
Page number:123
0 20 40 60 80 90 100 110 120 130 140 150-20Enthalpy(Btu/lb)
PRES
SUR
E PS
IA
R-22
SUMMARYThe P H Diagram is good tool to use to understand system operation and performance
It can be used for -Design-Understanding new system concepts-Troubleshooting
A knowledge of basic refrigeration system principles helps in the evaluation of refrigeration systems
Job name:Fundamentals of Refrigeration
Page number:124
Questions?Questions?Thank youThank you