1. Pressure Enthalpy without Tears Eugene Silberstein, M.S., CMHE, BEAP
Presented by
Eugene Silberstein, M.S., CMHE, BEAP
Suffolk County Community College
Cengage Learning
HVAC EXCELLENCE EDUCATORS CONFERENCE
SOUTH POINT HOTEL & CASINO
MARCH 31 – APRIL 2, 2014

2. If we change the way we look at things, the things we look at change

4. S IX

7. Chocolate Pudding

8. 74 39 28 23 19 18 22 17 15 14 13
1 x 1 x 72
2 x 2 x 18
1 x 2 x 36
2 x 3 x 12
1 x 3 x 24
2 x 4 x 9
1 x 4 x 18
2 x 6 x 6
1 x 6 x 12
3 x 4 x 6
1 x 8 x 9
3 x 3 x 8

10. LINES OF CONSTANT ENTHALPY
LINES OF CONSTANT PRESSURE
Pressure
(psia)
PRESSURE DROPS
PRESSURE RISES
HEAT CONTENT DECREASES
HEAT CONTENT INCREASES
Heat Content
Btu/lb

11. Pressure
(psia)
SATURATION CURVE
Heat Content
Btu/lb
Btu/lb

12. THE SATURATION CURVE
Under the curve, the refrigerant follows the pressure-temperature relationship
The left side of the saturation curve represents 100% liquid
The right side of the saturation curve represents 100% vapor
For non-blended refrigerants, one pressure corresponds to one temperature

13. LINES OF CONSTANT TEMPERATURE
Pressure
(psia)
LINES OF CONSTANT TEMPERATURE
Heat Content
Btu/lb

14. Pressure
(psia)
LINES OF CONSTANT VOLUME (ft3/lb)
Heat Content
Btu/lb

15. Pressure
(psia)
LINES OF CONSTANT ENTROPY
Heat Content
Btu/lb

16. Pressure
(psia)
LINES OF CONSTANT QUALITY
Heat Content
Btu/lb

17. PUT IT ALL TOGETHER…
Pressure
(psia)
Heat Content
Btu/lb

18. Pressure-Enthalpy (p-h) Diagram for R-12 (Simplified)
Pressure (psia)
160°F
140°F
221
120°F
172
100°F
132
80°F 99
60°F 72
40°F 52
20°F 36
0°F 24
Enthalpy in btu/lb (Heat Content)

19. Pressure-Enthalpy (p-h) Diagram for R-22 (Simplified)
Pressure (psia)
160°F
140°F
352
120°F
275
100°F
211
80°F
159
60°F
117
40°F 84
20°F 58
0°F 39
110
112
119
123
Enthalpy in btu/lb (Heat Content)

20. Pressure-Enthalpy (p-h) Diagram for R-410A (Simplified)
Pressure (psia)
160°F
140°F
557
120°F
434
100°F
334
80°F
251
60°F
186
40°F
133
20°F 93
0°F 63
123
133
140
143
148
152
Enthalpy in btu/lb (Heat Content)

21. REPEATING vs. NON-REPEATING CYCLES

22. High Pressure High Temperature
CONDENSER
Liquid
Vapor
High Pressure High Temperature
METERING DEVICE
COMPRESSOR
Low Pressure Low Temperature
EVAPORATOR

23. Subcooled Liquid
Saturated Refrigerant
Superheated Vapor
CONDENSER
METERING DEVICE
COMPRESSOR
EVAPORATOR

24. Pressure
Subcooled Region
Superheated Region
Saturated Region
Heat Content

25. Pressure
Heat Content

26. Pressure
(psia)
Heat Content
Btu/lb

27. Height Above Saturation
VAPOR
LIQUID

28. Saturation
VAPOR
LIQUID
Distance Below Saturation

29. Pressure
(psia)
Heat Content
Btu/lb

30. PUT IT ALL TOGETHER…
Pressure
(psia) A E B C D
Heat Content
Btu/lb

31. E to A: CONDENSER (Including discharge and liquid line)
Pressure
Heat Content
(psia)
Btu/lb
PUT IT ALL TOGETHER… A B C D E
E to A: CONDENSER (Including discharge and liquid line)
A to B: METERING DEVICE
B to C: EVAPORATOR
C to D: SUCTION LINE
D to E: COMPRESSOR A B C D E

32. NET REFRIGERATION EFFECT
The portion of the system that provides the desired cooling or conditioning of the space or products being treated. A E D B C

33. NET REFRIGERATION EFFECT
The larger the NRE, the greater the heat transfer rate per pound of refrigerant circulated
NRE is in the units of btu/lb
Cooling effect can be increased by increasing the NRE or by increasing the mass flow rate
The cooling effect can be decreased by decreasing the NRE or by decreasing the rate of refrigerant circulation through the system

34. NRE Example Heat Content at point B = 35 btu/lb
Heat Content at point C = 85 btu/lb
NRE = C – B = 85 btu/lb – 35 btu/lb
NRE = 50 btu/lb
Each pound of refrigerant can therefore hold 50 btu of heat energy
How many btu does it take to make 1 ton?

35. How Many btu = 1 Ton? 12,000 btu/hour = 1 Ton = 200 btu/min
From the previous example, how many lb/min do we have to move through the system to get 1 ton?
200 btu/min/ton ÷ 50 btu/lb = 4 lb/min
We must circulate 4 pounds of refrigerant through the system every minute to obtain one ton of refrigeration
Mass Flow Rate Per Ton

36. NRE and MFR/ton
The NRE determines the number of btu that a pound of refrigerant can hold
The larger the NRE the more btu can be held by the pound of refrigerant
As the NRE increases, the MFR/ton decreases
As the NRE decreases, the MFR/ton increases
NRE = Heat content at C – Heat content at B
MFR/ton = 200 ÷ NRE
Cool, huh?

38. THE SUCTION LINE
The line that connects the outlet of the evaporator to the inlet of the compressor. This line is field installed on split-type air conditioning systems. A E B D C

39. SUCTION LINE The suction line should be as short as possible
The amount of heat introduced to the system through the suction line should be minimized
Damaged suction line insulation increases the amount of heat added to the system and decreases the system’s operating efficiency
Never remove suction line insulation without replacing
Seal the point where insulation sections meet

40. A E E B D D C

41. HEAT OF WORK
The quantity, in btu/lb that represents the amount of heat that is added to the refrigerant during the compression process. A E B C D

42. HEAT OF WORK (HOW)
The HOW indicates the amount of heat added to a pound of refrigerant during compression
As the pressure of the refrigerant increases, the heat content of the refrigerant increases as well
Heat gets concentrated in the compressor
As HOW increases, efficiency decreases
As HOW decreases, system efficiency increases
HOW = Heat content at E – Heat content at D

43. HEAT OF COMPRESSION
The quantity, in btu/lb that represents the amount of heat that is added to the system, outside of the evaporator A E B C D

44. HEAT OF COMPRESSION (HOC)
The HOW indicates the amount of heat added to a pound of refrigerant outside the evaporator
Comprised of the HOW and the suction line
As HOC increases, efficiency decreases
As HOC decreases, system efficiency increases
HOW = Heat content at E – Heat content at C

45. TOTAL HEAT OF REJECTION
The quantity, in btu/lb that represents the amount of heat that is removed from the system. THOR includes the discharge line, condenser and liquid line. A E B C D

46. TOTAL HEAT OF REJECTION (THOR)
THOR indicates the total amount of heat rejected from a system
Refrigerant (hot gas) desuperheats when it leaves the compressor (sensible heat transfer)
Once the refrigerant has cooled down to the condensing temperature, a change of state begins to occur (latent heat transfer)
After condensing, refrigerant subcools
THOR = Heat content at E – Heat content at A
THOR = NRE + HOC

47. SUBCOOLING & FLASH GAS Subcooling is a good thing, right?
Flash gas is a good thing, right?
Are flash gas and subcooling related?
How can we tell?
Stay tuned...

48. (Only a slight Exaggeration)
HIGH SUBCOOLING....
(Only a slight Exaggeration) A B C D E
What happened to the amount of flash gas?

49. LARGE AMOUNT OF FLASH GAS.... (Only a slight Exaggeration)B C D
What happened to the subcooling?

50. SUBCOOLING & FLASH GAS
Subcooling and flash gas are inversely related to each other
As the amount of subcooling increases, the percentage of flash gas decreases
As the percentage of flash gas increases, the amount of subcooling decreases

51. COMPRESSION RATIO
Determined by dividing the high side pressure (psia) by the low side pressure (psia) A E
High-side pressure
Low-side pressure B C D

52. COMPRESSION RATIO
Represents the ratio of the high side pressure to the low side pressure
Directly related to the amount of work done by the compressor to accomplish the compression process
The larger the compression ratio, the larger the HOW and HOC and the lower the system MFR
The larger the HOW and HOC, the lower the system efficiency
Absolute pressures must be used

53. ABSOLUTE PRESSURE Absolute pressure = Gauge pressure + 14.7
Round off to 15, for ease of calculation
Example 1
High side pressure (psig) = 225 psig
High side pressure (psia) = = 240 psia
Low side pressure (psig) = 65 psig
Low side pressure (psia) = = 80 psia
Compression ratio = 240 psia ÷ 80 psia = 3:1

54. Low Side Pressure in a Vacuum?
First, convert the low side vacuum pressure in inches of mercury to psia
Use the following formula
 (30” Hg – vacuum reading) ÷ 2
Example
High side pressure = 245 psig
High side pressure (psia) = = 260 psia
Low side pressure = 4”Hg
Low side (psia) = (30”hg – 4”Hg) ÷ 2 = 13 psia
Compression ratio = 260 ÷ 13 = 20:1

55. Meet Tammy…

56. 90th Floor
2 Lawyers + 1 Tammy = Wasted Time
2nd Floor

65. Tammy’s 8-Hour Day 9am – 10 am Work on 2nd Floor 10am – 11am Walk up
11am – 12 noon Work on 90th Floor
12 noon – 1pm Walk down
1 pm – 2pm Lunch
2pm – 3 pm Work on 2nd Floor
3 pm – 4 pm Walk up
4pm – 5 pm Work on 90th Floor

66. Hmmmmmmmmmmmm
What if the law firm moves its 90th floor office to the 3rd floor?
How will this affect Tammy’s productivity?
Will she do more work? Less?
What the heck does this have to do with air conditioning?
How many licks does it take to get to the chocolaty center of a Tootsie Pop?

67. If Tammy’s office moves from the 90th floor to the 3rd floor, we get something like this….

68. Tammy’s 8-Hour Day 9:00 am – 10:00 am Work on 2nd Floor
10:00 am – 10:05 am Walk up to 3rd Floor
10:05 am – 11:05 noon Work on 3rd Floor
11:05 am – 11:10 am Walk down to 2nd Floor
11:10 am – 12:10 pm Work on 2nd Floor
12:10 pm – 1:10 pm Lunch
1:10 pm – 1:15 pm Walk up to 3rd Floor
1:15 pm – 2:15 pm Work on 3rd Floor
2:15 pm – 2:20 pm Walk down to 2nd Floor
2:20 pm – 3:20 pm Work on 2nd Floor
3:20 pm – 3:25 pm Walk up to 3rd Floor
3:25 pm – 4:25 pm Work on 3rd Floor
4:25 pm – 4:30 pm Walk down to 2nd Floor
4:30 pm – 5:00 pm Work on 2nd Floor

69. Office Comparison Which is better? 2nd Floor  90th Floor
4 hours of work
3 hours of walking up and down the stairs
1 hour lunch
Day ends on the 90th Floor
2nd Floor  3rd Floor
6 ½ hours of work
30 minutes of walking up and down the stairs
1 hour lunch
Day ends on the 2nd Floor
Which is better?

70. COMPRESSION RATIO Lower compression ratios  higher system efficiency
Higher compression ratios  lower system efficiency
The closer the head pressure is to the suction pressure, the higher the system efficiency, all other things being equal and operational

71. Causes of High Compression Ratio (High Side Issues)
Dirty or blocked condenser coil
Recirculating air through the condenser coil
Defective condenser fan motor
Defective condenser fan motor blade
Defective wiring at the condenser fan motor
Defective motor starting components (capacitor) at the condenser fan motor

72. Causes of High Compression Ratio (Low Side Issues)
Dirty or blocked evaporator coil
Dirty air filter
Defective evaporator fan motor
Dirty blower wheel (squirrel cage)
Defective wiring at the evaporator fan motor
Closed supply registers
Blocked return grill
Loose duct liner
Belt/pulley issues

73. THEORETICAL HORSEPOWER PER TON
Determines how much compressor horsepower is required to obtain 1 ton of cooling
The ft-lb is a unit of work
The ft-lb/min is a unit of power
33,000 ft-lb/min = 1 Horsepower
The conversion factor between work and heat is 778 ft-lb/btu
33,000 ft-lb/min/hp ÷ 778 ft-lb/btu =
42.42 btu/min/hp

74. THEORETICAL HORSEPOWER PER TON
THp/ton = (MFR/ton x HOW) ÷ 42.42
For example, if we had a system that had an NRE of 50 and a HOW of 10, the THp/ton would be:
THp/ton = (200/NRE) x HOW ÷ 42.42
THp/ton = (200/50) x 10 ÷ 42.42
THp/ton = 4 x 10 ÷ 42.42
THp/ton = 40 ÷ 42.42
THp/ton = 0.94

76. THp/ton Example
If we had a 20-Hp reciprocating compressor and the THp/ton calculation yielded a result of 2 hp/ton, what would the expected cooling capability of the system be?
16 TONS
5 TONS
25 TONS
1 TON
3.8 TONS
20 TONS
3,492 TONS
10 TONS

77. What Affects the THp/ton Number?
The Net Refrigeration Effect (NRE)
The Heat of Work (HOW)
What Affects the NRE and HOW?
Suction pressure
Discharge pressure
Compression Ratio
Airflow through the coils
Blowers and fans
And so on, and so on, and so on, and so on….

78. Get the Picture?

79. MASS FLOW RATE OF THE SYSTEM
The amount of refrigerant that flows past any given point in the system every minute
Not to be confused with MFR/ton
MFR/system is the actual refrigerant flow, while MFR/ton is the flow per ton
MFR/system can be found by multiplying the MFR/ton by the number of tons of system capacity, or
MFR/system = (42.42 x Compressor HP) ÷ HOW

80. COOL STUFF
As the HOW increases, the MFR/system decreases, and vice versa
As the Compression Ratio increases, the HOW increases
As head pressure increases, or as suction pressure decreases, the Compression Ratio increases
As the MFR/system decreases, the capacity of the evaporator, condenser and compressor all decrease
Let’s take a closer look…

81. Evaporator Capacity = MFR/system x NRE x 60
A function of the MFR/system and the NRE
The MFR/system is in lb/min, the NRE is in btu/lb and the capacity of the evaporator is in btu/hour
Evaporator Capacity = MFR/system x NRE x 60
Btu Lb Btu Min
Hour Min Lb Hour

82. EVAPORATOR CAPACITY
If the NRE or the MFR/system decreases, the evaporator capacity also decreases
The “60” is a conversion factor from btu/min to btu/hour, given that there are 60 minutes in an hour
Divide the evaporator capacity in btu/hour by 12,000 to obtain the evaporator capacity in tons

83. Condenser Capacity = MFR/system x THOR x 60
A function of the MFR/system and the THOR
The MFR/system is in lb/min, the THOR is in btu/lb and the capacity of the condenser is in btu/hour
Condenser Capacity = MFR/system x THOR x 60
Btu Lb Btu Min
Hour Min Lb Hour

84. Compresser Capacity = MFR/system x Specific Volume
COMPRESSOR CAPACITY
A function of the MFR/system and the Specific volume of the refrigerant at the inlet of the compressor
Calculated in cubic feet per minute, ft3/min
Compresser Capacity = MFR/system x Specific Volume
ft Lb ft3
Min Min Lb

85. COEFFICIENT OF PERFORMANCE (COP)
The ratio of the NRE compared to the HOC
If the HOC remains constant, any increases in NRE will increase the COP
If the NRE remains constant, any decrease in HOC will increase the COP
The COP is a contributing factor to the EER of an air conditioning system
COP is a unitless value

86. COP EXAMPLE Heat content at point B = 35 btu/lb
Heat content at point C = 104 btu/lb
Heat content at point E = 127 btu/lb
NRE = 104 btu/lb – 35 btu/lb = 69 btu/lb
HOC = 127 btu/lb – 104 btu/lb = 23 btu/lb
COP = 69 btu/lb ÷ 23 btu/lb = 3
Notice that the “3” has no units

87. ENERGY EFFICIENCY RATIO (EER)
A ratio of the amount of btus transferred to the amount of power used
In the units of btu/watt
The conversion between btus and watts is 3.413
One watt of power generates btu
For example, if a system required 50,000 btu of heat, 14,650 watts of electric heat (14.65 kw) can be used

88. ENERGY EFFICIENCY RATIO (EER), Cont’d.
The efficiency rating of an air conditioning system is the COP
For each btu/lb introduced to the system in the suction line and the compressor, a number of btus equal to the NRE are absorbed into the system via the evaporator
To convert the COP to energy usage, we multiply the COP by 3.413

89. EER EXAMPLE The NRE of a system is 70 btu/lb
The HOC of the same system is 20 btu/lb
The COP is 70 btu/lb ÷ 20 btu/lb = 3.5
The EER = COP x 3.413
EER = 3.5 x 3.413
EER = 11.95

90. SEASONAL EER (SEER) Takes the entire conditioning system into account
Varies depending on the geographic location of the equipment
Ranges from 10% t0 30% higher than EER
So, if the EER is 10, the SEER will range from 11 to 13

91. From the P-H Chart, We Can Find
Compression Ratio
NRE
HOC
HOW
THOR
COP
MFR/ton
THp/ton
MFR/system
Evaporator Capacity
Condenser Capacity
Compressor Capacity
EER of the System
SEER
Okay, Okay, Okay… How do I plot one of these things?

92. An R-22 A/C System… Condenser saturation temperature 120°F
Condenser outlet temperature 100°F
Evaporator saturation temperature 40°F
Evaporator outlet temperature 50°F
Compressor inlet temperature 60°F
Compressor Horsepower: 4 hp

93. Pressure-Enthalpy (p-h) Diagram for R-22 (Simplified)
Pressure (psia)
180°F
160°F
140°F
352
0.7
120°F
275
100°F
211
80°F
159
60°F
117
40°F 84
20°F 58
0°F 39
-20°F 25
-40°F
Enthalpy in btu/lb (Heat Content)

94. Pressure-Enthalpy (p-h) Diagram for R-22 (Simplified)
Pressure (psia)
180°F
160°F
140°F
352
0.7
120°F
275
100°F
211
80°F
159
60°F
117
40°F 84
20°F 58
0°F 39
-20°F 25
-40°F
Enthalpy in btu/lb (Heat Content)

95. Pressure-Enthalpy (p-h) Diagram for R-22 (Simplified)
Pressure (psia)
180°F
160°F
140°F
352 A B
0.7
120°F
275
100°F
211
80°F
159
60°F
117
40°F 84 C
20°F 58
0°F 39
-20°F 25
-40°F
Enthalpy in btu/lb (Heat Content)

96. Pressure-Enthalpy (p-h) Diagram for R-22 (Simplified)
Pressure (psia)
180°F
160°F
140°F
352 A B
0.7
120°F
275
100°F
211
80°F
159
60°F
117
40°F 84 C D
20°F 58
0°F 39
-20°F 25
-40°F
Enthalpy in btu/lb (Heat Content)

97. Pressure-Enthalpy (p-h) Diagram for R-22 (Simplified)
Pressure (psia)
180°F
160°F
140°F
352 A B
0.7
120°F
275
100°F
211
80°F
159
60°F
117
40°F 84 C D
20°F 58
0°F 39
-20°F 25
-40°F
Enthalpy in btu/lb (Heat Content)

98. Pressure-Enthalpy (p-h) Diagram for R-22 (Simplified)
Pressure (psia)
180°F
160°F
140°F
352 A B E
0.7
120°F
275
100°F
211
80°F
159
60°F
117
40°F 84 C D
20°F 58
0°F 39
-20°F 25
-40°F
Enthalpy in btu/lb (Heat Content)

99. Pressure-Enthalpy (p-h) Diagram for R-22 (Simplified)
Pressure (psia)
180°F
160°F
140°F
352 A B E
0.7
120°F
275
100°F
211
80°F
159
60°F
117
40°F 84 C D
20°F 58
High: 275 psia
Low: 84 psia
“A”: 40 btu/lb
“B”: 40 btu/lb
“C”: 110 btu/lb
“D”: 112 btu/lb
“E”: 125 btu/lb
0°F 39
-20°F 25
-40°F
Enthalpy in btu/lb (Heat Content)

100. COMPRESSION RATIO = 275 psia ÷ 84 psia = 3.27:1
High: 275 psia
Low: 84 psia
“A”: 40 btu/lb
“B”: 40 btu/lb
“C”: 110 btu/lb
“D”: 112 btu/lb
“E”: 125 btu/lb
COMPRESSION RATIO
HIGH SIDE PRESSURE (psia)
LOW SIDE PRESSURE (psia)
COMPRESSION RATIO = 275 psia ÷ 84 psia = 3.27:1

101. HEAT OF WORK = 125 btu/lb – 112 btu/lb = 13 btu/lb
High: 275 psia
Low: 84 psia
“A”: 40 btu/lb
“B”: 40 btu/lb
“C”: 110 btu/lb
“D”: 112 btu/lb
“E”: 125 btu/lb
HEAT OF WORK
HEAT CONTENT AT “E” – HEAT CONTENT AT “D”
HEAT OF WORK = 125 btu/lb – 112 btu/lb = 13 btu/lb

102. HEAT OF COMPRESSION= 125 btu/lb – 110 btu/lb = 15 btu/lb
High: 275 psia
Low: 84 psia
“A”: 40 btu/lb
“B”: 40 btu/lb
“C”: 110 btu/lb
“D”: 112 btu/lb
“E”: 125 btu/lb
HEAT OF COMPRESSION
HEAT CONTENT AT “E” – HEAT CONTENT AT “C”
HEAT OF COMPRESSION= 125 btu/lb – 110 btu/lb = 15 btu/lb

103. NRE = 110 btu/lb – 40 btu/lb = 70 btu/lb
High: 275 psia
Low: 84 psia
“A”: 40 btu/lb
“B”: 40 btu/lb
“C”: 110 btu/lb
“D”: 112 btu/lb
“E”: 125 btu/lb
NET REFRIGERATION EFFECT
HEAT CONTENT AT “C” – HEAT CONTENT AT “B”
NRE = 110 btu/lb – 40 btu/lb = 70 btu/lb

104. MFR/ton = 200 ÷ NRE =200 ÷ 70 btu/lb = 2.86 lb/min/ton
High: 275 psia
Low: 84 psia
“A”: 40 btu/lb
“B”: 40 btu/lb
“C”: 110 btu/lb
“D”: 112 btu/lb
“E”: 125 btu/lb
MASS FLOW RATE PER TON
200 ÷ NRE
MFR/ton = 200 ÷ NRE =200 ÷ 70 btu/lb = 2.86 lb/min/ton

105. THOR = 125 btu/lb – 40 btu/lb = 85 btu/lb
High: 275 psia
Low: 84 psia
“A”: 40 btu/lb
“B”: 40 btu/lb
“C”: 110 btu/lb
“D”: 112 btu/lb
“E”: 125 btu/lb
TOTAL HEAT OF REJECTION
HEAT CONTENT AT “E” – HEAT CONTENT AT “A”
THOR = 125 btu/lb – 40 btu/lb = 85 btu/lb

106. THp/ton = 2.86 lb/min/ton x 13 btu/lb ÷ 42.42 = 0.88 Hp/ton
High: 275 psia
Low: 84 psia
“A”: 40 btu/lb
“B”: 40 btu/lb
“C”: 110 btu/lb
“D”: 112 btu/lb
“E”: 125 btu/lb
THEORETICAL HORSEPOWER PER TON
[MFR/ton x HOW] ÷ 42.42
THp/ton = 2.86 lb/min/ton x 13 btu/lb ÷ = 0.88 Hp/ton

107. COEFFICIENT OF PERFORMANCE
High: 275 psia
Low: 84 psia
“A”: 40 btu/lb
“B”: 40 btu/lb
“C”: 110 btu/lb
“D”: 112 btu/lb
“E”: 125 btu/lb
COEFFICIENT OF PERFORMANCE
NRE ÷ HOC
COP = 70 btu/lb ÷ 15 btu/lb = 4.67

108. MASS FLOW RATE OF THE SYSTEM
High: 275 psia
Low: 84 psia
“A”: 40 btu/lb
“B”: 40 btu/lb
“C”: 110 btu/lb
“D”: 112 btu/lb
“E”: 125 btu/lb
MASS FLOW RATE OF THE SYSTEM
[42.42 x Compressor HP] ÷ HOW
MFR/system = [42.42 x 4] ÷ 13 btu/lb = lb/min

109. CAPACITY OF THE EVAPORATOR
High: 275 psia
Low: 84 psia
“A”: 40 btu/lb
“B”: 40 btu/lb
“C”: 110 btu/lb
“D”: 112 btu/lb
“E”: 125 btu/lb
CAPACITY OF THE EVAPORATOR
NRE x MFR/system x 60
CAP/evap = 70 btu/lb x x 60 = 54,810 btu/hour
CAP/evap = 54,810 btu/hour ÷ 12,000 btu/hour/ton = 4.57 tons

110. CAPACITY OF THE CONDENSER
High: 275 psia
Low: 84 psia
“A”: 40 btu/lb
“B”: 40 btu/lb
“C”: 110 btu/lb
“D”: 112 btu/lb
“E”: 125 btu/lb
CAPACITY OF THE CONDENSER
THOR x MFR/system x 60
CAP/cond = 85 btu/lb x x 60 = 66,555 btu/hour
CAP/cond = 66,555 btu/hour ÷ 12,000 btu/hour/ton = 5.55 tons

111. CAPACITY OF THE COMPRESSOR
High: 275 psia
Low: 84 psia
“A”: 40 btu/lb
“B”: 40 btu/lb
“C”: 110 btu/lb
“D”: 112 btu/lb
“E”: 125 btu/lb
CAPACITY OF THE COMPRESSOR
MFR/system x Specific Volume
CAP/comp = x 0.7 = ft3/min

112. ENERGY EFFICIENCY RATIO
High: 275 psia
Low: 84 psia
“A”: 40 btu/lb
“B”: 40 btu/lb
“C”: 110 btu/lb
“D”: 112 btu/lb
“E”: 125 btu/lb
ENERGY EFFICIENCY RATIO
COP x 3.413
EER = 4.67 x = 15.94
SEER (low end) = 1.1 x EER = 1.1 x = 17.5
SEER (high end) = 1.3 x EER = 1.3 x = 20.7

113. 275 psia
84 psia
61 psia

114. Let’s See What Happened…
CR = 4.5
HOW = 14
HOC = 25
NRE = 60
MFR/ton = 3.33 lb/min
THp/ton = 1.1
COP = 2.4
MFR/system = 12.12
CAP/evap = 43,632 btu
EER = 8.19
CR = 3.27
HOW = 13
HOC = 15
NRE = 70
MFR/ton = 2.86 lb/min
THp/ton = 0.88
COP = 4.67
MFR/system = 13.05
CAP/evap = 66,555 btu
EER = 15.9

116. Properly Operating System
Heat Content “A” = 40 btu/lb
Heat Content “B” = 40 btu/lb
Heat Content “C” = 109 btu/lb
Heat Content “D” = 111 btu/lb
Heat Content “E” = 125 btu/lb
High side pressure = 267 psig
High side pressure = 282 psia
Low side pressure = 70 psig
Low side pressure = 85 psia
Compressor Hp = 2.5 Hp
Specific Volume = 0.7
NRE = 69 btu/lb
HOW = 14 btu/lb
HOC = 16 btu/lb
THOR = 85 btu/lb
Comp. Ratio = 3.32
MFR/ton = 2.9 lb/min/ton
THp/ton = 0.96 Hp/ton
COP = 4.3
MFR/system = 7.58 lb/min
CAP/evap = 31,381 btuh
CAP/cond = 38,658 btuh
CAP/comp = 5.3 ft3/min
EER = 14.68
SEER = – 19.1
A/B C D E

118. Clogged Cap Tube System
Heat Content “A” = 39 btu/lb
Heat Content “B” = 39 btu/lb
Heat Content “C” = 112 btu/lb
Heat Content “D” = 118 btu/lb
Heat Content “E” = 134 btu/lb
High side pressure = 226 psig
High side pressure = 241 psia
Low side pressure = 59 psig
Low side pressure = 74 psia
Compressor Hp = 2.5 Hp
Specific Volume = 0.9
NRE = 73 btu/lb
HOW = 16 btu/lb
HOC = 22 btu/lb
THOR = 95 btu/lb
Comp. Ratio = 3.26
MFR/ton = 2.74 lb/min/ton
THp/ton = 1.03 Hp/ton
COP = 3.3
MFR/system = 6.63 lb/min
CAP/evap = 29,039 btuh
CAP/cond = 37,791 btuh
CAP/comp = 5.97 ft3/min
EER = 11.26
SEER = – 14.64
A/B C D E

120. System Okay
System Clogged
Increase/Decrease
NRE 69 73
Increase
HOW 14 16
HOC 22
THOR 85 95
Comp. Ratio
3.32
3.26
Decrease
MFR/ton
2.9
2.74
THp/ton
0.96
1.03
COP
4.3
3.3
MFR/system
7.58
6.63
CAP/evap
31,381 (2.62)
29,039 (2.42)
CAP/cond
38,658 (3.22)
37,791 (3.15)
CAP/comp
5.3
5.97
EER
14.68
11.26
SEER
16.15 – 19.1
12.39 – 14.64

121. Contact Information...
Eugene Silberstein
Suffolk County Community College
1001 Crooked Hill Road
Brentwood, NY 11717
(631)