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without Tears

Presented by

Eugene Silberstein

Suffolk County Community College

HVAC EXCELLENCE EDUCATORS CONFERENCE

Imperial Palace, Las Vegas, Nevada

March 8-10, 2009

LINES OF CONSTANT PRESSURE

Pressure

(psia)

PRESSURE DROPS

PRESSURE RISES

HEAT CONTENT DECREASES

HEAT CONTENT INCREASES

Heat Content

Btu/lb

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

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

12 2025 31 35 8 8 8 8 8 9 9 9 9 9 1 1 1 1 1

0 2 4 6 8 0 2 4 6 8 0 0 0 0 0

Enthalpy in btu/lb (Heat Content)

0 2 4 6 8

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

15 24 31 40 46

110

112

119

123

Enthalpy in btu/lb (Heat Content)

Vapor

High Pressure High Temperature

High Pressure High Temperature

Low Pressure Low Temperature

Low Pressure Low Temperature

Liquid

Vapor

CONDENSER

METERING DEVICE

COMPRESSOR

EVAPORATOR

Heat Content

Pressure

(psia)

A

A

E

E

B

B

C

C

D

D

Heat Content

Btu/lb

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

E

D

NET REFRIGERATION EFFECT

The portion of the system that provides the desired cooling or conditioning of the space or products being treated.

B

C

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

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?

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

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?

E

B

D

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.

C

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

E

B

C

D

HEAT OF COMPRESSION

The quantity, in btu/lb that represents the amount of heat that is added to the refrigerant during the compression process.

HEAT OF COMPRESSION (HOC)

- The HOC 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 HOC increases, efficiency decreases
- As HOC decreases, efficiency increases
- HOC = Heat content at E – Heat content at D

E

B

C

D

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.

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

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...

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

E

High-side pressure

Low-side pressure

B

C

D

COMPRESSION RATIO

Determined by dividing the high side pressure (psia) by the low side pressure (psia)

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 HOC and the lower the system MFR
- The larger the HOC, the lower the efficiency
- Absolute pressures must be used

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) = 225 + 15 = 240 psia
- Low side pressure (psig) = 65 psig
- Low side pressure (psia) = 65 + 15 = 80 psia
- Compression ratio = 240 psia ÷ 80 psia = 3:1

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) = 245 + 15 = 260 psia
- Low side pressure = 4”Hg
- Low side (psia) = (30”hg – 4”Hg) ÷ 2 = 13 psia
- Compression ratio = 260 ÷ 13 = 20:1

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

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?

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

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

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

Office ComparisonWhich is better?

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

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

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

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

THEORETICAL HORSEPOWER PER TON

- THp/ton = (MFR/ton x HOC) ÷ 42.42
- For example, if we had a system that had an NRE of 50 and a HOC of 10, the THp/ton would be:

THp/ton = (200/NRE) x HOC ÷ 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

1 TON

3.8 TONS

25 TONS

16 TONS

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?

20 TONS

3,492 TONS

10 TONS

What Affects the THp/ton Number?

- The Net Refrigeration Effect (NRE)
- The Heat of Compression (HOC)

What Affects the NRE and HOC?

- 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….

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) ÷ HOC

COOL STUFF

- As the HOC increases, the MFR/system decreases, and vice versa
- As the Compression Ratio increases, the HOC 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…

Evaporator Capacity = MFR/system x NRE x 60

Btu Lb Btu 60 Min

Hour Min Lb Hour

EVAPORATOR CAPACITY- 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

- 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

Condenser Capacity = MFR/system x THOR x 60

Btu Lb Btu 60 Min

Hour Min Lb Hour

CONDENSER CAPACITY- 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

Compresser Capacity = MFR/system x Specific Volume

ft3 Lb ft3

Min Min Lb

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

COEFFICIENT OF PERFORMANCE (COP)

- The ratio of the NRE compared to the HOC, assuming a saturated cycle
- If the cycle is not saturated, add the suction line heat 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

COP EXAMPLE #1

- Heat content at point B = 35 btu/lb
- Heat content at point C = 104 btu/lb
- Heat content at point D = 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

COP EXAMPLE #2

- Heat content at point B = 35 btu/lb
- Heat content at point C = 105 btu/lb
- Heat content at point D = 110 btu/lb
- Heat content at point E = 140 btu/lb
- NRE = 105 btu/lb – 35 btu/lb = 70 btu/lb
- HOC = 140 btu/lb – 110 btu/lb = 30 btu/lb
- SL superheat = 110 btu/lb – 105 btu/lb = 5 btu/lb
- COP = [70 btu/lb] ÷ [30 btu/lb + 5 btu/lb] = 2

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 3.413 btu
- For example, if a system required 50,000 btu of heat, 14,650 watts of electric heat (14.65 kw) can be used

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

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

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

Compression Ratio

NRE

HOC

HOW

THOR

COP

MFR/ton

THp/ton

MFR/system

Evaporator Capacity

Condenser Capacity

Compressor Capacity

EER of the System

SEER

From the P-H Chart, We Can FindOkay, Okay, Okay… How do I plot one of these things?

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

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

3 4 4 5 1 1 1 1 1

2 0 6 3

1 1 1 2 2

0 2 7 1 5

Enthalpy in btu/lb (Heat Content)

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

3 4 4 5 1 1 1 1 1

2 0 6 3

1 1 1 2 2

0 2 7 1 5

Enthalpy in btu/lb (Heat Content)

B

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

C

20°F

58

0°F

39

-20°F

25

-40°F

3 4 4 5 1 1 1 1 1

2 0 6 3

1 1 1 2 2

0 2 7 1 5

Enthalpy in btu/lb (Heat Content)

B

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

C

D

20°F

58

0°F

39

-20°F

25

-40°F

3 4 4 5 1 1 1 1 1

2 0 6 3

1 1 1 2 2

0 2 7 1 5

Enthalpy in btu/lb (Heat Content)

B

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

C

D

20°F

58

0°F

39

-20°F

25

-40°F

3 4 4 5 1 1 1 1 1

2 0 6 3

1 1 1 2 2

0 2 7 1 5

Enthalpy in btu/lb (Heat Content)

B

Pressure-Enthalpy (p-h) Diagram for R-22 (Simplified)

Pressure (psia)

180°F

160°F

140°F

352

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

3 4 4 5 1 1 1 1 1

2 0 6 3

1 1 1 2 2

0 2 7 1 5

Enthalpy in btu/lb (Heat Content)

B

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

Pressure-Enthalpy (p-h) Diagram for R-22 (Simplified)

Pressure (psia)

180°F

160°F

140°F

352

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

3 4 4 5 1 1 1 1 1

2 0 6 3

1 1 1 2 2

0 2 7 1 5

Enthalpy in btu/lb (Heat Content)

LOW SIDE PRESSURE (psia)

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

COMPRESSION RATIO = 275 psia ÷ 84 psia = 3.27:1

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 “D”

HEAT OF COMPRESSION= 125 btu/lb – 112 btu/lb = 13 btu/lb

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

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

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

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 HOC] ÷ 42.42

THp/ton = 2.86 lb/min/ton x 13 btu/lb ÷ 42.42 = 0.88 Hp/ton

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 + SL]

COP = [70 btu/lb] ÷ [15 btu/lb + 2 btu/lb] = 4.12

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] ÷ HOC

MFR/system = [42.42 x 4] ÷ 13 btu/lb = 13.05 lb/min

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 13.05 x 60 = 54,810 btu/hour

CAP/evap = 54,810 btu/hour ÷ 12,000 btu/hour/ton = 4.57 tons

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 13.05 x 60 = 66,555 btu/hour

CAP/cond = 66,555 btu/hour ÷ 12,000 btu/hour/ton = 5.55 tons

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 = 13.05 x 0.7 = 9.13 ft3/min

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 3.413 = 15.94

SEER (low end) = 1.1 x EER = 1.1 x 15.94 = 17.5

SEER (high end) = 1.3 x EER = 1.3 x 15.94 = 20.7

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 = 16.15 – 19.1

Properly Operating SystemA/B C D E

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 = 12.39 – 14.64

Clogged Cap Tube SystemA/B C D E

Contact Information...

Eugene Silberstein

Suffolk County Community College

1001 Crooked Hill Road

Brentwood, NY 11717

(631) 851-6897

E-mail: [email protected]

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