Thomas J Kelly. Fundamentals of Refrigeration. Sr. Engineering Instructor Carrier Corporation. August 20, Page number: 1.

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1 Thomas J Kelly Sr. Engineering Instructor Carrier Corporation August 20,

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 terms 3. Develop a PH diagram to use as a system analysis tool 4. 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 2

3 COMFORT VS. PROCESS The mechanical refrigeration process is used for two major types of market Comfort Cools and dehumidifies people Process Controls temperature and humidity for things The basic process is the same 3

4 THE REFRIGERATION MARKET CHAIN Food 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 4

5 REFRIGERATION TERMS PH diagram Superheat Enthalpy Refrigeration Effect Flash Gas What is he talking about? Sub-cooling Vapor Quality High Side / Low Side Latent Heat Sensible Heat Saturated Suction Throttling Range Heat of Compression Expansion Device Heat of Rejection Refrigeration Effect 5

6 BASIC SYSTEM COMPONENTS Every system has 4 basic components Evaporator Absorbs the heat from the air or load Cold Mixture Air out: 59.7F DB / 57.3F WB 47 F 78 PSI EVAPORATOR Air in: 80F DB / 67F WB Cold Vapor 59 F 78 PSI 6

7 BASIC SYSTEM COMPONENTS Every system has 4 basic components Evaporator Hot Vapor 220 F 175PSI Compressor Raises the pressure from the evaporator pressure to the condensing temperature Air out: 59.7F DB / 57.3F WB 47 F 78 PSI EVAPORATOR COMPRESSOR Air in: 80F DB / 67F WB Cold Vapor 59 F 78 PSI 7

BASIC SYSTEM COMPONENTS Every system has 4 basic components Evaporator 110 F 175PSI CONDENSER Air out: 95F DB Hot Vapor 220 F 175PSI Compressor Hot Liquid Air in:

8 BASIC SYSTEM COMPONENTS Every system has 4 basic components Evaporator 110 F 175PSI CONDENSER Air out: 95F DB Hot Vapor 220 F 175PSI Compressor Hot Liquid Air in: 95F DB Condenser COMPRESSOR Air out: 59.7F DB / 57.3F WB Rejects the heat from the load and system losses 47 F 78 PSI EVAPORATOR Air in: 80F DB / 67F WB 59 F 78 PSI 8

9 BASIC SYSTEM COMPONENTS Every system has 4 basic components Evaporator 110 F 175PSI CONDENSER Hot Liquid Air out: 95F DB 220 F 175PSI Compressor METERING DEVICE Air in: 95F DB Condenser Metering device Regulates the flow and decreases the pressure from condensing pressure to evaporator pressure Cold Mixture Air out: 59.7F DB / 57.3F WB 47 F 78 PSI EVAPORATOR COMPRESSOR Air in: 80F DB / 67F WB 59 F 78 PSI 9

10 BASIC SYSTEM COMPONENTS High Side High Side CONDENSER Compressor discharge to Metering device METERING DEVICE Low Side COMPRESSOR Metering device to Compressor suction EVAPORATOR Low Side 10

11 4 LAW OF SYSTEM OPERATION 1. Heat only moves from higher temperature to a lower temperature NO FLOW 70º 70º 70º FLOW 32º 212º FLOW 70º 11

12 4 LAW OF SYSTEM OPERATION 1. Heat only moves from higher temperature to a lower temperature 2. Energy required to change of states of matter is large Sensible Heat 71 º F 70 º F 1 BTU / LB 12

13 4 LAW OF SYSTEM OPERATION 1. Heat only moves from higher temperature to a lower temperature 2. Energy required to change of states of matter is large Latent Heat SATURATED VAPOR 212ºF 212 º F 970 BTU / LB 13

14 4 LAW OF SYSTEM OPERATION 1. 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 9 PSIA 5 PSI 230º F 14

4 LAW OF SYSTEM OPERATION 1. Heat only moves from higher temperature to a lower temperature 2. Energy required to change of states of matter is large 3.

15 4 LAW OF SYSTEM OPERATION 1. 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 15

16 TEMPERATURE ENTHALPY PLOT R 718 ( Water) as an example TEMPERATURE ºF Enthalpy is the total heat content Enthalpy = Sensible + Latent 0 Enthalpy(Btu/lb) 16

17 TEMPERATURE ENTHALPY PLOT R 718 ( Water) as an example 1 pound at standard barometric pressure TEMPERATURE ºF ICE 16 Latent heat of Fusion 144 Btu/lb 160 LIQUID Sub-cooled Solid Enthalpy(Btu/lb) 17

18 TEMPERATURE ENTHALPY PLOT R 718 ( Water) as an example 1 pound at standard barometric pressure 256 Superheated Vapor VAPOR TEMPERATURE ºF Sub-cooled Liquid ICE LIQUID Enthalpy(Btu/lb) Latent heat of Vaporization Condensation 1 Btu/lb 970 Btu/lb 0.45 Btu/lb

19 TEMPERATURE ENTHALPY PLOT R 718 ( Water) as an example 1 pound at standard barometric pressure 256 Superheated Vapor VAPOR TEMPERATURE ºF Sub-cooled Liquid ICE LIQUID 100% Saturated Liquid 1 Btu/lb 970 Btu/lb 0.45 Btu/lb Enthalpy(Btu/lb) 100% Saturated Liquid

20 P H DIAGRAM Plots enthalpy vs. pressure P10 P9 Critical Point P8 PRESSURE PSIA P7 P6 P5 P4 P3 P2 Saturated Liquid Saturated Vapor P1 Enthalpy(Btu/lb) 20

21 P H DIAGRAM Take note the lines become closer at higher pressure less latent capacity P10 P9 Critical Point 422 PRESSURE PSIA P7 P6 P5 P Btu/lb P2 P1 Saturated Liquid 970 Btu/lb Saturated Vapor Enthalpy(Btu/lb) 21

22 P H DIAGRAM Vapor Quality is percentage of the mixture P10 P9 P8 Sub-cooled Liquid Critical Point PRESSURE PSIA P7 P6 P5 P4 P Superheated Vapor P2 P1 Vapor Quality Enthalpy(Btu/lb) 22

23 P H DIAGRAM Refrigerant Blends P10 P9 P8 Sub-cooled Liquid Critical Point PRESSURE PSIA P7 P6 P5 P4 P3 Bubble Point Blends Dew Point Superheated Vapor P2 P1 Vapor Quality Enthalpy(Btu/lb) 23

24 P H DIAGRAM Temperature Lines P10 PRESSURE PSIA ºF 450 ºF TEMPERATURE P1 Enthalpy(Btu/lb) 24

25 P H DIAGRAM Entropy Lines PRESSURE PSIA P ENTROPY 451 Btu/ºR 450 Btu/ºR P1 Enthalpy(Btu/lb) 25

26 P H DIAGRAM Specific Volume Lines P10 PRESSURE PSIA SPECIFIC VOLUME 1.1 ft 3 /lb 26.8 ft 3 /lb P1 Enthalpy(Btu/lb) 26

27 P H DIAGRAM Time to test your skill SATURATED LIQUID SATURATED VAPOR SUBCOOLED LIQUID SATURATED MIXTURE SUPERHEATED VAPOR 27

28 PH DIAGRAM FOR R-22 TEMPERATURE ENTROPY PRESSURE PSIA SPECIFIC VOLUME R Enthalpy(Btu/lb) 28

29 BASIC SYSTEM ON THE PH DIAGRAM PRESSURE PSIA EXPANSION DEVICE CONDENSER EVAPORATOR COMPRESSOR R Enthalpy(Btu/lb) 29

30 EVAPORATOR TYPES Air cooled Water cooled (cooler) 30

31 EVAPORATOR PROCESS Two processes 1. Evaporation change the mixture of gas and liquid refrigerant to all vapor 2. Superheating Increase temperature above saturated suction Superheat is required to assure vapor at the compressor But has negative impact on total system efficiency Cold Mixed Phase Saturated Vapor Cold Superheated Vapor Evaporation Superheat 31

32 EVAPORATOR OPERATION Flash Gas - Vapor quality entering evaporator Refrigeration Effect Total heat absorbed by evaporator 47 F 78 PSI EVAPORATOR Air out: 59.7F DB / 57.3F WB Air in: 80F DB / 67F WB 59 F 78 PSI Cold Mixed Phase 47F - 78PSI Flash Gas Refrigeration Effect Cold Superheated Vapor 59F 78PSI 32

33 COMPRESSOR TYPES Reciprocating Scroll Screw Rotary Centrifugal 33

34 COMPRESSOR PROCESS 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 Hot Superheated Vapor Saturated Vapor Compression Cold Superheated Vapor 34

35 COMPRESSSOR OPERATION Heat of Compression Heat added from the compression process Compression Ratio Discharge pressure / suction pressure EVAPORATOR COMPRESSOR 50 F 55PSI 220 F 175PSI Hot Superheated Vapor 220F 175PSI Compression Ratio Compression Heat of Compression Cold Superheated Vapor 59F 78PSI 35

36 ROTARY COMPRESSORS Used in : Small AC units Appliances Uses rotating piston and a sliding vane 36

37 RECIPROCATING COMPRESSORS Used in : AC, Refrigeration & Appliances Uses reciprocating piston and reed valves 37

38 SCROLL COMPRESSOR Used in : AC, Refrigeration & Appliances Uses a stationary scroll and a rotating scroll and has no valves 38

39 SCREW COMPRESSOR Used in : AC & Refrigeration Uses a stationary screw and a rotating screw and a slide valve 39

40 CONDENSER TYPES Air cooled Water cooled 40

41 CONDENSER PROCESS Three processes 1. De-Superheating Lower temperature to saturated condensing temp. 2. Condensing Condense vapor to liquid 3. 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 Sub-cooling Condensing Hot Superheated Vapor 220F 175PSI Hot Sub-cooled Liquid 110F 175PSI Saturated Vapor De-superheating 41

42 CONDENSER OPERATION Heat of Rejection Refrigerant effect plus heat of compression 110 F 175PSI CONDENSER Air out: 95F DB 220 F 175PSI EVAPORATOR Air in: 95F DB COMPRESSOR Heat of Rejection Hot Superheated Vapor Hot Sub-cooled Liquid 42

43 EXPANSION DEVICES TYPES Fixed Metering TXV Floats 43

44 EXPANSION DEVICE PROCESS 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 Hot Sub-cooled Liquid 110F 175PSI Expansion Device Cold Mixed Phase 47F 70PSI 44

45 EXPANSION DEVICE OPERATION Throttling Range Pressure drop available across the metering device METERING DEVICE CONDENSER 110 F 175PSI 47 F 78 PSI EVAPORATOR COMPRESSOR Hot Hot Sub-cooled Sub-cooled Liquid Liquid 110F 175PSI Expansion Device Throttling Range Cold Mixed Phase 47F 70PSI 45

46 PH DIAGRAM - SYSTEM INEFFICIENCIES Liquid Line P Condenser Coil P Discharge Line P Evaporator Coil P Suction Line P 46

47 P H DIAGRAM FOR R-134A REFRIGERANT PRESSURE PSIA R R Enthalpy(Btu/lb) 47

48 R-22 VS. R-134A REFRIGERANT CYCLE PRESSURE PSIA R-22 R Enthalpy(Btu/lb) 48

49 P H DIAGRAM FOR R-404 REFRIGERANT PRESSURE PSIA R-22 R Enthalpy(Btu/lb) 49

50 R-22 VS. R-404 REFRIGERANT CYCLE PRESSURE PSIA R-22 R Enthalpy(Btu/lb) 50

51 THE BASIC REFRIGERATION SYSTEM Basic System LIQUID LINE DRIER MOISTURE LIQUID INDICATOR EXPANSION VALVE CONDENSER RECIEVER EVAPORATOR COMPRESSOR SUCTION ACCUMULATOR Basic Refrigeration System Same system with a few special features 51

52 PH DIAGRAM - HIGH TEMPERATURE CONDENSER PRESSURE PSIA TXV TR=202 PSI THR = 81 BTU/# EVAPORATOR RE = 67 BTU/# COMPRESSOR CR=3.2 R Enthalpy(Btu/lb) 52

53 REFRIGERATION SYSTEM TYPES Self Contained Condensing units Rack systems 53

54 TYPICAL LARGER MARKET LAYOUT MEAT-DELI AIR COOLED CONDENSER WALK-IN COOLER MEDIUM TEMP RACK LOW TEMP RACK MULTI DECK DELI/DAIRY SINGLE DECK MEAT DISPLAY WALK-IN FREEZER REACH IN FROZEN FOOD FROZEN FOOD 54

55 TYPICAL SMALLER MARKET LAYOUT AIR COOLED CONDENSER WALK-IN COOLER MEDIUM/LOW TEMP RACK MEAT/DELI MULTI DECK DELI/DAIRY FROZEN FOODS 55

56 CONVENIENCE STORE LAYOUT LOW MED MED TEMP COND UNIT MULTI DECK DELI/DAIRY MEAT/DELI FROZEN FOODS 56

57 MEDIUM TEMPERATURE REFRIGERATION Typical Cases 15F to 35F PRODUCE AND DELI LIQUID LINE DRIER MOISTURE LIQUID INDICATOR EXPANSION VALVE CONDENSER RECIEVER EVAPORATOR COMPRESSOR SUCTION ACCUMULATOR 57

58 PH DIAGRAM - MEDIUM TEMPERATURE CONDENSER THR = 94 BTU/# PRESSURE PSIA TXV TR=236 PSI 20 EVAPORATOR RE = 70 BTU/# COMPRESSOR CR=5.1 R Enthalpy(Btu/lb) 58

59 LOW TEMPERATURE REFRIGERATION Typical Cases -15F to -30F FROZEN FOOD AND ICE CREAM LIQUID LINE DRIER MOISTURE LIQUID INDICATOR EXPANSION VALVE CONDENSER RECIEVER EVAPORATOR COMPRESSOR SUCTION ACCUMULATOR 59

60 PH DIAGRAM - LOW TEMPERATURE CONDENSER THR = 96 BTU/# TXV TR=276 PSI PRESSURE PSIA EVAPORATOR COMPRESSOR CR=17.2 RE = 63 BTU/# R Enthalpy(Btu/lb) 60

61 REFRIGERATION EVAPORATORS Cases Ice Cream Air SST -25F -35F Produce Air SST +33F 20F Meat Air SST 27F 15F Frozen Food Air SST -15F -25F Dairy Air SST 25F 15F 61

62 REFRIGERATION EVAPORATORS Unit Coolers Reach in Walk In Blast freezers 62

63 EVAPORATOR DEFROST Air Defrost Electric Defrost Hot Gas Reverse Cycle Three pipe Drain pan heaters 63

64 DEFROST DIFFERENTIAL VALVES Defrost with Differential Regulating Valve Liquid line Discharge Line 64

DEFROST DIFFERENTIAL VALVES Defrost with Differential Regulating Valve CONDENSER LIQUID LINE DRIER MOISTURE LIQUID INDICATOR LIQUID DIFFERENTIAL VALVE SOLENOID VALVE

65 DEFROST DIFFERENTIAL VALVES Defrost with Differential Regulating Valve CONDENSER LIQUID LINE DRIER MOISTURE LIQUID INDICATOR LIQUID DIFFERENTIAL VALVE SOLENOID VALVE SOLENOID VALVE CHECK VALVE EVAPORATOR EXPANSION VALVE RECIEVER DISCHARGE DIFFERENTIAL VALVE EVAPORATOR SOLENOID VALVE COMPRESSOR SUCTION ACCUMULATOR EVAPORATOR PRESSURE REGULATOR 65

66 Evaporator Pressure Regulators Maintains constant pressure in the evaporator 66

67 Evaporator Pressure Regulators LIQUID LINE DRIER MOISTURE LIQUID INDICATOR EXPANSION VALVE CONDENSER RECIEVER EVAPORATOR COMPRESSOR EVAPORATOR PRESSURE SUCTION REGULATOR ACCUMULATOR 67

68 Evaporator Pressure Regulator Multiple Evaporator systems with common suction Maintains stable evaporator pressure to control temperature Common Suction Header 10 F 44 psig Receiver 15 F 20 F 68

69 PH DIAGRAM MULTIPLE EVAPORATORS CONDENSER TXV PRESSURE PSIA MEDIUM STAGE LOW STAGE EVAPORATOR COMPRESSOR R Enthalpy(Btu/lb) 69

70 SUCTION ACCUMULATOR Protects the compressor from liquid Separates vapor from liquid Provides for oil return Oil Return Orifice IN Fusible Plug 70

71 RECIEVERS Provide storage volume for excess refrigerant Pump down storage 71

72 REFRIGERATION COMPRESSORS Self Contained Condensing Units Rack Systems 72

73 REFRIGERATION COMPRESSORS Scroll 1 to 15 HP Refrigeration duty differences Vapor Injection Liquid Injection Applications Self contained Condensing units Rack systems 73

74 REFRIGERATION COMPRESSORS CONDENSER TXV PRESSURE PSIA GAIN INJECTION LOW STAGE EVAPORATOR COMPRESSOR R Enthalpy(Btu/lb) 74

75 REFRIGERATION COMPRESSORS Reciprocating Hermetic 1 to 5 HP Refrigeration duty differences Applications Self contained Condensing units Rack systems 75

76 REFRIGERATION COMPRESSORS Reciprocating Semi-Hermetic 3 to 60 HP Refrigeration duty differences Cooling fans Compound cooling Applications Stand alone Condensing units Rack systems 76

77 REFRIGERATION COMPRESSORS Reciprocating Semi-Hermetic Typical low temperature De-superheating valve 77

78 COMPOUND COMPRESSORS Single compressor Multiple compressor 78

79 COMPOUND COOLING CONDENSER TXV PRESSURE PSIA MEDIUM STAGE LOW STAGE EVAPORATOR COMPRESSOR R Enthalpy(Btu/lb) 79

80 REFRIGERATION COMPRESSORS Screw Compressor 20 to 140 HP Refrigeration duty differences Oil control system Liquid injection Applications Condensing units Rack systems Built up system 80

81 Crankcase Pressure Regulator Prevents over-pressurization of Two-Stage Compressor crankcase CONDENSER TXV PRESSURE PSIA MEDIUM STAGE LOW STAGE EVAPORATOR COMPRESSOR R Enthalpy(Btu/lb) 81

Crankcase Pressure Regulator On two-stage compressors systems and Low Temperature - - Compression Ratio > 10:1 Discharge of One Cylinder is De- Superheated and Used as

82 Crankcase Pressure Regulator On two-stage compressors systems and Low Temperature - - Compression Ratio > 10:1 Discharge 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. 82

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 Units 2. Single Units with Multiple Compressors. 3. Variable Speed Compressors 4. Compressor Cylinder Unloading 5. Hot Gas Bypass 83

84 CAPACITY CONTROL 1. Multiple Units 2. Single Units with Multiple Compressors. 3. Variable Speed Compressors 84

85 CAPACITY CONTROL 4. Compressor Cylinder Unloading 85

86 HOT GAS BYPASS CONTROL LIQUID LINE DRIER MOISTURE LIQUID INDICATOR EXPANSION VALVE CONDENSER RECIEVER EVAPORATOR COMPRESSOR EVAPORATOR PRESSURE SUCTION REGULATOR ACCUMULATOR 86

87 Hot Gas Bypass Regulators 87

88 Hot Gas Bypass Bypasses High Pressure Refrigerant to the System s Low Pressure Side. Regulates to Maintain a Set Minimum Suction Pressure. De-Superheating TXV Bypass to Suction Bypass to Evaporator Inlet 88

89 BYPASS TO SUCTION WITH SUCTION ACCUMULATOR BYPASS SOLENOID BYPASS REGULATOR LIQUID INJECTION THERMO VALVE LIQUID INJECTION SOLENOID VALVE SUCTION ACCUMULATOR SUCTION UPSTREAM OF ACCUMULATOR 89

90 BYPASS TO SUCTION WITH SUCTION ACCUMULATOR BYPASS SOLENOID BYPASS REGULATOR LIQUID INJECTION THERMO VALVE LIQUID INJECTION SOLENOID VALVE OUTLET OF ACCUMULATOR UPSTREAM OF ACCUMULATOR SUCTION * IF A BOILOUT ACCUMULATOR IS USED, LOCATE LCL BULB UPSTREAM 90

91 BYPASS TO SUCTION WITH SUCTION ACCUMULATOR BYPASS SOLENOID BYPASS REGULATOR LIQUID INJECTION THERMO VALVE Constant head pressure is required during periods of bypass. LIQUID INJECTION SOLENOID VALVE SUCTION SUCTION ACCUMULATOR 91

BYPASS TO EVAPORATOR INLET BYPASS TO EVAPORATOR INLET BYPASS SOLENOID DIRECT ACTING BYPASS REGULATOR ADVANTAGES: Provides a False Load Defrost the

92 BYPASS TO EVAPORATOR INLET BYPASS TO EVAPORATOR INLET BYPASS SOLENOID DIRECT ACTING BYPASS REGULATOR ADVANTAGES: Provides a False Load Defrost the Coil, A/C Evaporator serves as mixing chamber Minimizes components Excellent Oil Return THERMO VALVE LIQUID LINE SOLENOID VALVE EVAPORATOR COMPRESSOR 92

93 BYPASS TO EVAPORATOR INLET BYPASS TO EVAPORATOR INLET BYPASS SOLENOID DIRECT ACTING BYPASS REGULATOR With the evaporator BELOW the compressor, bypass to evaporator inlet assures proper oil return at low loads. COMPRESSOR THERMO VALVE LIQUID LINE SOLENOID VALVE EVAPORATOR 93

94 REFRIGERATION CONDENSERS Air Cooled Water Cooled 94

95 Head Pressure Control 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 Control hwater regulating valve hcondenser Fan Cycling hvane / Damper Control System hsplit Condenser System h Flooded Head Pressure Control 95

96 Head Pressure Control Air Cooled Units Fan Cycling HEAD PRESSURE Fan on Fan off TIME 96

97 Head Pressure Control Air Cooled Units Variable Speed Fan Water Cooled Units Water regulating Valve 97

98 HEAD PRESSURE CONTROL CONSTANT LOAD AT REDUCED CONDENSING TEMPERATURE CONDENSER TXV PRESSURE PSIA MEDIUM STAGE LOW STAGE EVAPORATOR COMPRESSOR R Enthalpy(Btu/lb) 98

99 CONDENSER HEAD PRESSURE CONTROL CONDENSER TEMPERATURE CONTROL HEAD PRESSURE CONTROL VALVE LIQUID LINE DRIER MOISTURE LIQUID INDICATOR FAN CYCLING CONTROL SOLENOID VALVE EXPANSION VALVE OIL SEPERATOR OIL FILTER CONDENSER COMPRESSOR OIL LEVEL CONTROL OIL PRESSURE SAFETY CONTROL RECIEVER BALL VALVE SUCTION FILTER -DRIER LOW PRESSURE CONTROL SOLENOID VALVE HOT GAS BYPASS REGULATOR HIGH -LOW PRESSURE CONTROL SUCTION ACCUMULATOR EVAPORATOR PRESSURE REGULATOR EVAPORATOR EVAPORATOR TEMPERATURE CONTROL 99

100 Flooded Condenser Condenser Bypass Receiver Condenser Outlet 100

101 FLOODED CONDENSER CONTROL 101

102 METERING DEVICES IN REFRIGERATION Expansion Valves - -Equalizer - Constant pressure valves Hand Valves 102

103 OPR Manual Adjustment Outlet Pressure regulators Inlet Pressure Regulated Outlet Pressure 103

104 IPR Manual Adjustment Inlet Pressure Regulators Outlet Pressure Regulated Inlet Pressure 104

DESUPERHEATERS Reduce compressor superheat 400 293 125 CONDENSER 200 140 100 TXV PRESSURE PSIA 60 57 40 20 17 10

105 DESUPERHEATERS Reduce compressor superheat CONDENSER TXV PRESSURE PSIA DE-SUPERHEATER LOW STAGE EVAPORATOR COMPRESSOR R Enthalpy(Btu/lb) 105

106 REFRIGERATION SYSTEM VALVES Control Isolation CONDENSER TEMPERATURE CONTROL LIQUID LINE DRIER MOISTURE LIQUID INDICATOR FAN CYCLING CONTROL SOLENOID VALVE EXPANSION VALVE OIL SEPERATOR OIL FILTER CONDENSER COMPRESSOR OIL LEVEL CONTROL OIL PRESSURE SAFETY CONTROL RECIEVER BALL VALVE SUCTION FILTER -DRIER LOW PRESSURE CONTROL SOLENOID VALVE HOT GAS BYPASS REGULATOR HIGH -LOW PRESSURE CONTROL SUCTION ACCUMULATOR EVAPORATOR PRESSURE REGULATOR EVAPORATOR EVAPORATOR TEMPERATURE CONTROL 106

107 SOLENOIDS VALVES Provide Control Function - On / Off Control - Normally Open / Normally closed Used -Pump down - Circuit isolation -Hot Gas isolation - Defrost Isolation 107

108 REFRIGERATION VALVES Ball Valves Diaphragm Valves Packed Angle Valves Globe Valves Pressure Relief Valves - Condensers - Pressure Vessels Check Valves 108

109 REFRIGERATION SYSTEM PROTECTORS Moisture Liquid Indicators Filter Driers CONDENSER TEMPERATURE CONTROL LIQUID LINE DRIER MOISTURE LIQUID INDICATOR FAN CYCLING CONTROL SOLENOID VALVE EXPANSION VALVE OIL SEPERATOR OIL FILTER CONDENSER COMPRESSOR OIL LEVEL CONTROL OIL PRESSURE SAFETY CONTROL RECIEVER SOLENOID VALVE BALL VALVE SUCTION FILTER -DRIER LOW PRESSURE CONTROL SUCTION ACCUMULATOR HOT GAS BYPASS REGULATOR HIGH -LOW PRESSURE CONTROL EVAPORATOR PRESSURE REGULATOR EVAPORATOR EVAPORATOR TEMPERATURE CONTROL 109

system charge Locations : Liquid line - Between liquid line

110 SIGHT GLASSES MOISTURE INDICATORS Provide an indication of refrigerant flow & moisture content Provide an indication of system charge Locations : Liquid line - Between liquid line filterdrier outlet & TXV inlet Oil Line - On oil separator or reservoir outlet 110

111 LIQUID LINE FILTER - DRIER Removes contaminants and chemical reaction products Filter-Driers remove Particles Water Acids Removes Solid and Sludge 111

112 SUCTION LINE FILTER - DRIER Suction line filter - Driers 112

113 OIL CONTROL SYSTEMS Oil system controls CONDENSER TEMPERATURE CONTROL LIQUID LINE DRIER MOISTURE LIQUID INDICATOR FAN CYCLING CONTROL SOLENOID VALVE EXPANSION VALVE OIL SEPERATOR OIL FILTER CONDENSER COMPRESSOR OIL LEVEL CONTROL OIL PRESSURE SAFETY CONTROL RECIEVER SOLENOID VALVE BALL VALVE SUCTION FILTER -DRIER LOW PRESSURE CONTROL SUCTION ACCUMULATOR HOT GAS BYPASS REGULATOR HIGH -LOW PRESSURE CONTROL EVAPORATOR PRESSURE REGULATOR EVAPORATOR EVAPORATOR TEMPERATURE CONTROL 113

-Oil reservoir -Check valve TO CONDENSER OIL LINE FILTER CHECK VALVE OIL

114 OIL CONTROL SYSTEMS PROTECTS THE COMPRESSORS TO CONTROL PROPER OIL LEVEL SYSTEM -Oil level control -Oil separator -Oil sight glass -Oil line filter -Oil reservoir -Check valve TO CONDENSER OIL LINE FILTER CHECK VALVE OIL RESERVOIR DISCHARGE HEADER SUCTION HEADER OIL SEPARATOR OIL LEVEL CONTROL 114

115 OIL CONTROL SYSTEMS Low 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 TO CONDENSER OIL LINE FILTER OIL SEPARATOR TO CONDENSER CHECK VALVE OIL RESERVOIR DISCHARGE HEADER OIL LEVEL CONTROL OIL LINE FILTER DISCHARGE HEADER SUCTION HEADER SUCTION HEADER OIL SEPARATOR RESERVOIR OIL LEVEL CONTROL 115

116 TEMPERATURE & PRESSURE CONTROLS Temperature Controls Pressure Controls CONDENSER TEMPERATURE CONTROL LIQUID LINE DRIER MOISTURE LIQUID INDICATOR FAN CYCLING CONTROL SOLENOID VALVE EXPANSION VALVE OIL SEPERATOR OIL FILTER CONDENSER COMPRESSOR OIL LEVEL CONTROL OIL PRESSURE SAFETY CONTROL RECIEVER SOLENOID VALVE BALL VALVE SUCTION FILTER -DRIER LOW PRESSURE CONTROL SUCTION ACCUMULATOR HOT GAS BYPASS REGULATOR HIGH -LOW PRESSURE CONTROL EVAPORATOR PRESSURE REGULATOR EVAPORATOR EVAPORATOR TEMPERATURE CONTROL 116

117 TEMPERATURE CONTROL APPLICATIONS Evaporator temperature sensing Discharge air temperature sensing Product temperature sensing Return air temperature sensing Evaporator coil freeze protection Defrost termination 117

PRESSURE CONTROL APPLICATIONS Low Pressure

control - High Temperature alarm - Defrost

Capacity control High Pressure Controls -

118 PRESSURE CONTROL APPLICATIONS Low Pressure Controls - Temperature control - Pump down control - High Temperature alarm - Defrost termination - Low pressure limit / alarm - Capacity control High Pressure Controls - High pressure cut-out - High pressure alarm - Condenser head pressure control Oil Pressure Controls - Oil pressure safety 118

119 ECONOMIZER CYCLE Improving Stage efficiency CONDENSER TXV PRESSURE PSIA ECONOMIZER LOW STAGE EVAPORATOR COMPRESSOR R Enthalpy(Btu/lb) 119

HEAT RECLAIM SYSTEMS Recovery of Condenser heat for space heating HEAT RECLAIM COIL LIQUID LINE DRIER MOISTURE LIQUID INDICATOR LIQUID DIFFERENTIAL VALVE SOLENOID VALVE CONDENSER SOLENOID

120 HEAT RECLAIM SYSTEMS Recovery of Condenser heat for space heating HEAT RECLAIM COIL LIQUID LINE DRIER MOISTURE LIQUID INDICATOR LIQUID DIFFERENTIAL VALVE SOLENOID VALVE CONDENSER SOLENOID VALVE CHECK VALVE EVAPORATOR EXPANSION VALVE HEAT RECLAIM VALVE DISCHARGE DIFFERENTIAL VALVE COMPRESSOR RECIEVER SUCTION ACCUMULATOR EVAPORATOR EVAPORATOR PRESSURE REGULATOR SOLENOID VALVE 120

121 SYSTEM TYPES Direct Refrigerant runs directly to cases Indirect Secondary cooling circuit is used 121

122 Practice Example PH chart example, Let s look at a refrigeration example and plot a low temperature system 122

123 SUMMARY The P H Diagram is good tool to use to understand system operation and performance PRESSURE PSIA 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 R Enthalpy(Btu/lb) 123

124 Thank you Questions? 124

Energy Use in Refrigeration Systems

2012 Rocky Mountain ASHRAE Technical Conference Energy Use in Refrigeration Systems PRESENTED BY: Scott Martin, PE, LEED AP BD+C Objectives Understand mechanical refrigeration terms Describe how heat is