Chapter10 Refrigeration Cycle

10-1 Vapor-Compression Cycle

10-1-1 The Reversed Carnot Cycle10-1-1 The Reversed Carnot Cycle

w

qCOP L

c

14

14

ssTT

ssT

LH

L

LH

L

TT

T

T

s

4 1

23TH

TL

1

1

L

H

TT

Coefficient of Performance

Disadvantages

•Process 2-3 is difficult to be Fulfill in compressor

•Process 4-1 will do harm to turbine

10-1-2 The Ideal Vapor-Compression Refrigeration Cycl10-1-2 The Ideal Vapor-Compression Refrigeration Cyclee

condenser

Equipments:

1

2

3

4

compressor

Expansion valve

evaporator

T

s

TH

TL1

2

3

4

condenser

compressor

evaporator

Capillary tube

10-1-3 The COP of 10-1-3 The COP of Vapor-Compression Cycleh-s diagram

h

s

1

2

34

Usually p1, p2 are available

h

s

1

2

34

From p1, get h1”, s1”

h1 = h1” s1 = s1”

From p2 , s1, get h2

From p2 , get h2’

h3= h2’

h4 = h3

w

qCOP L

12

41

hh

hh

p-h diagram

p

h

1

23

4

10-2 Refrigerant

•Ammonia

•CFC(chlorofluorocarbons)

•water

Good refrigerant

High enthalpy of vaporization

Not too low evaporator pressure

Not too high condenser pressure

Nontoxic

Noncorrosive

Chemically stable

Low cost

10-3 Heat PumpAn equipment Absorbing heat from environment for heating purpose

T

s

TH

T01

2

3

4

12

32

hh

hhCOPhp

Heat pump for heating

Heat pump for refrigeration

10-4 Innovative Vapor-compression Refrigeration Systems

10-4-1 Regenerative Vapor Compression cycleEquipmentsEquipments

condenser

evaporator

Heat exchange

r

separator

compressor

T

s

TH

TL1

2

3

4

T-s DiagramT-s Diagram

2’

1’

10-4-2 Cascade Refrigeration Systems10-4-2 Cascade Refrigeration Systems

condenser

evaporator

T

s

T0

T-s DiagramT-s Diagram

10-4-3 Multistage Compression Refrigeration Syste10-4-3 Multistage Compression Refrigeration Systemsms

condenser

evaporator

Flash chamber

1

2

3

heat exchanger

45

6

7

8

9

T

s

1

2

3

4

5

67

8

9

10-4-4 Multipurpose Refrigeration Systems with a Single C10-4-4 Multipurpose Refrigeration Systems with a Single Compressorompressor

condenser

Freezer

refrigerator

1

2

3

4

5

6

Alternative path

T

s

1

2

3

4

5

10-4-5 Liquefaction of Gas10-4-5 Liquefaction of Gas

Heat exchanger

Make up gas

Liquid removed

Multistage compressor

1

2

3

4

5

T

s

1

2

1

3

45

10-5 Gas Refrigeration cycle

10-4-1 Equipments

Heat exchanger

QH

Heat exchanger

QL

compressor

turbine

T

s

p2

p1

1

2

3

4

T0

TL

10-4-2 COP of Gas Refrigeration Cycle

4132

41

hhhh

hhCOP

4132

41

TTTTC

TTC

p

p

1

1

41

32

TT

TT

T

s

1

2

3

4

T0

TL

k

k

T

T

T

T 1

4

3

1

2

1

2

41

32

T

T

TT

TT

1

1

1

2

TT

COP

T

s

1

2

3

4

T0

TL

1

11

k

k

Since

1

11

k

kCOP

•To decrease compression ratio can increase COP

•To To decrease compression ratio will decrease power ratio

T

s

T0

TL

T

s

T0

TL

1

2

4

5

3

q

6

q

10-4-3 Regenerative Gas Refrigeration Cycle

Heat exchanger

QH

Heat exchanger

QL

compressor

turbine

regenerator

1 2

34 5

6

10-6 Absorption Refrigeration System

heat

condenser

evaporator

=compressor

Refrigerant: Ammonia

Transport medium: Water

Refrigerant: Water

Transport medium: Lithium bromide

10-6 Adsorption Refrigeration

Solar energy

Active carbon

evaporator

condenser

Cooling Tube

Solar energyNight

Cold air

Active carbon

Vacuum tubeCooling tower

The End of This Chapter

Thank You