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© Hitachi, Ltd. 2017. All rights reserved. Cycle Simulation and Prototyping of Single-Effect Double-Lift Absorption Chiller Hitachi, Ltd. Research & Development Group Thermal Fluidic Systems Research Department May/17/2017 Tatsuo Fujii

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Page 1: Cycle Simulation and Prototyping of Single-Effect …hpc2017.org/wp-content/uploads/2017/06/o464.pdf · 2. Single-Effect Double-Lift ... Evaporator Auxiliary Generator Absorber Condenser

© Hitachi, Ltd. 2017. All rights reserved.

Cycle Simulation and Prototyping of Single-Effect Double-Lift Absorption Chiller

Hitachi, Ltd. Research & Development GroupThermal Fluidic Systems Research Department

May/17/2017

Tatsuo Fujii

Page 2: Cycle Simulation and Prototyping of Single-Effect …hpc2017.org/wp-content/uploads/2017/06/o464.pdf · 2. Single-Effect Double-Lift ... Evaporator Auxiliary Generator Absorber Condenser

© Hitachi, Ltd. 2017. All rights reserved.

1. Introduction2. Single-Effect Double-Lift (SEDL) absorption cooling cycle3. Cycle Simulation

Contents

1

4. Prototyping and Experiment5. Conclusions

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2© Hitachi, Ltd. 2017. All rights reserved.

1. Introduction – activating low temperature heat –

Current status of driving temperatures of absorption chillers

Hot Water DrivenAbsorption Chiller

Temp.: 60°C 90°C 120°C 150°C 180°C~

Direct fired Absorption Chiller/Heater

Steam DrivenAbsorption Chiller

Double effectSingle effect

Not Available forCooling Use

(75°C)

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3© Hitachi, Ltd. 2017. All rights reserved.

2. Single-Effect Double-Lift (SEDL) absorption cycle

High temp. Generator

Pressure

Temperature

Low temp.Generator

Evaporator

Auxiliary Generator

Absorber

Condenser

AuxiliaryAbsorber

AHX HHX

LHX

Heat Input

Heat Output

SEDL absorption cooling cycle

Ø Combination of single-effect and double-lift (half-effect) absorption cycle

Ø Consist of 7 phase changing heat exchanger and 3 solution heat exchanger

Ø Proposed by Schweigler et. al. in 1990’s

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4© Hitachi, Ltd. 2017. All rights reserved.

3. Cycle Simulation

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5© Hitachi, Ltd. 2017. All rights reserved.

3. Cycle Simulation – Modeling of SEDL cycle

Simulation model supported two-step evaporator and absorber (E/A).à Operated under 4 pressure levels

Strong solution

Refrigerant Weak solution

Cooling waterChilled water

Configuration of two-step E/A

E1

E2

A1

A2

pH

pM

pL1

pL2

Chilled water

Cooling water

Hot water (Heat source)

C AG

AA

AHX

E1

E2

HG

LG

HHX

LHX

A1

A2

Refrigerant liquid

Refrigerant vapour

Solution (Absorbent)

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6© Hitachi, Ltd. 2017. All rights reserved.

3. Cycle Simulation – Computing strategy

Basically, cycle calculation is consist of three levels.

(3) Components levelEnergy and mass balance in each component in the same pressure level

(2) Same pressure levelMass balance in each pressure level pH, pM, pL1 and pL2

(1) Whole system levelEnergy and mass balance in the whole cycle

Input conditions

C AG HGC AG HG

COP,etc.

Chilled water

Cooling water

Hot water (Heat source)

C AG

AA

AHX

E1

E2

HG

LG

HHX

LHX

A1

A2

Refrigerant liquid

Refrigerant vapour

Solution (Absorbent)

Page 8: Cycle Simulation and Prototyping of Single-Effect …hpc2017.org/wp-content/uploads/2017/06/o464.pdf · 2. Single-Effect Double-Lift ... Evaporator Auxiliary Generator Absorber Condenser

7© Hitachi, Ltd. 2017. All rights reserved.

Chilled water

Cooling water

Hot water (Heat source)

C AG

AA

AHX

E1

E2

HG

LG

HHX

LHX

A1

A2

Refrigerant liquid

Refrigerant vapour

Solution (Absorbent)

48

49

50

51

52

53

54

55

56

94

95

96

97

98

99

100

101

102

2-step EA 1-step EA 2-step EA 1-step EA

Hot

wat

er te

mpe

ratu

re (T

HW

-out

)

(°C

)

Cap

acity

(QE)

, CO

P (%

)

Evaporator and absorber formation

QE COP THW-out

Chilled water: 13-8°C Chilled water: 15-7°C

THW-in: 95°C

3. Cycle Simulation – Effect of two-step E/A

As similar as conventional machines, two-step E/A configuration improved the capacity and COP. à We employed two-step E/A for the prototype chiller.

Calculation under the same heat exchanger size

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8© Hitachi, Ltd. 2017. All rights reserved.

49

50

51

52

53

54

55

56

57

94

95

96

97

98

99

100

101

102

HG-LG-AGA-AA-C

HG-AG-LGA-AA-C

HG-LG-AGA-C-AA

HG-AG-LGA-C-AA

Hot

wat

er te

mpe

ratu

re (T

HW

-out

)

(°C

)

Cap

acity

(QE)

, CO

P (%

)

Hot water and cooling water flow order

QE COP THW-out

Hot water ->Cooling water ->

THW-in: 95°C,Chilled water in-out: 13-8°C

3. Cycle Simulation – Effect of water circulation –

Circulation methods for hot water and cooling water were examined and “HG-LG-AG” for the hot water and “A-AA-C” for the cooling water were selected.

Calculation under the same heat exchanger size

Chilled water

Cooling water

Hot water (Heat source)

C AG

AA

AHX

E1

E2

HG

LG

HHX

LHX

A1

A2

Refrigerant liquid

Refrigerant vapour

Solution (Absorbent)

Page 10: Cycle Simulation and Prototyping of Single-Effect …hpc2017.org/wp-content/uploads/2017/06/o464.pdf · 2. Single-Effect Double-Lift ... Evaporator Auxiliary Generator Absorber Condenser

9© Hitachi, Ltd. 2017. All rights reserved.

4. Prototyping and Experiment

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10© Hitachi, Ltd. 2017. All rights reserved.

4. Prototyping and experiment – Cycle flow –

Prototype of SEDL chiller was designed with adoption of two-step evaporator and absorber, and optimized water circulating method.

Hot water (Heat source)

E1

E2

A1

A2

LHX HHX

AHX

LG AA AG C HG

Chilled water

Cooling water

This prototype can also be operated as a normal double-lift cycle.

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11© Hitachi, Ltd. 2017. All rights reserved.

4. Prototyping and experiment – Whole system –

Experimental equipment(Hot/Chilled/Cooling water supply)

Prototype of SEDL chiller and experimental equipment are setup for performance test.

Hot water

Chilled water

Cooling water

(Return)

Prototype of SEDL absorption chiller

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12© Hitachi, Ltd. 2017. All rights reserved.

4. Prototyping and experiment – SEDL chiller

Prototype chiller was manufactured, considering real product.

Prototype of SEDL absorption chiller

Evaporator

Auxiliary absorber

Solution heat exchangers

Absorber

Condenser

High temp. generator

Auxiliary generator

Low temp. generator

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13© Hitachi, Ltd. 2017. All rights reserved.

4. Prototyping and experiment – Result (1) –

Basic performance data in DL and SEDL operations were measured.

Item UnitOperating mode

DL SEDL

Cooling capacity kW 42.0 106.1

Chilled waterInlet °C 15.0 12.0

Outlet °C 7.0 7.0

Cooling waterInlet °C 30.1 30.9

Outlet °C 34.5 36.6

Hot water(Heat source)

Inlet °C 60.0 88.7Outlet °C 56.3 53.0

Page 15: Cycle Simulation and Prototyping of Single-Effect …hpc2017.org/wp-content/uploads/2017/06/o464.pdf · 2. Single-Effect Double-Lift ... Evaporator Auxiliary Generator Absorber Condenser

14© Hitachi, Ltd. 2017. All rights reserved.

4. Prototyping and experiment – Result (2) –

The simulator was validated by comparing with experimental data.

40

45

50

55

55 60 65 70 75 80 85 90 95 100

Hot

wat

er o

utle

t te

mpe

ratu

re (

°C)

THW-out (SIM)THW-out (EXP)

0

20

40

60

80

100

120

55 60 65 70 75 80 85 90 95 100

Cap

acity

(QE)

, CO

P (

%)

Hot water inlet temperature (THW-in) (°C)

COP (SIM) COP (EXP)QE (SIM) QE (EXP)

Chilled water inlet: 13.0°C for SIM, 12.8~13.1°C for EXPCooling water inlet: 31.0°C for SIM, 30.7~30.9°C for EXP

Accuracy;THW-out: ±1°C (approx.)Capacity: ±5% of max. valueIn case of THW-in = 60°C, effect of heat leak increases relatively.

We are using this simulator considering this accuracy as enough level.

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15© Hitachi, Ltd. 2017. All rights reserved.

5. Conclusions

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16© Hitachi, Ltd. 2017. All rights reserved.

5. Conclusions – activating low temperature heat –

Current status of driving temperatures of absorption chillers

Hot Water DrivenAbsorption Chiller

Temp.: 60°C 90°C 120°C 150°C 180°C~

Direct fired Absorption Chiller/Heater

Steam DrivenAbsorption Chiller

Double effectSingle effect

(75°C)

SEDLAbsorption Chiller

Half effect

Page 18: Cycle Simulation and Prototyping of Single-Effect …hpc2017.org/wp-content/uploads/2017/06/o464.pdf · 2. Single-Effect Double-Lift ... Evaporator Auxiliary Generator Absorber Condenser

17© Hitachi, Ltd. 2017. All rights reserved.

0.000

0.001

0.002

0.003

0.004

0.005

0.006

Conventionalsingle-effect chiller

SEDL chiller(This work)

Hot

wat

er p

umpi

ng p

ower

(k

Wel/k

WC

ool)

0

20

40

60

80

100

120

140

Conventionalsingle-effect chiller

SEDL chiller(This work)

Coo

ling

capa

city

per

unit

hot w

ater

vol

ume

(MJ/

m3 H

W)

5. Conclusions – Comparisons with SE chillers

SEDL reduces hot water volume into about half amount, thus 1) increases cooling capacity per unit hot water volume (MJ/m3

HW), and 2) reduces pumping power for hot water (kWel/kWCool).

Chilled water: 12 -> 7°CCooling water:27 -> 33°CHot water inlet: 95°C

Flow rates of chilled water and cooling water are commonHot water inlet: 95°CHW pumping head: 20m

Cooling Capacity Pumping power

Í2 Í0.5

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18© Hitachi, Ltd. 2017. All rights reserved.

5. Conclusions – remarks –

(1) A simulation program to study the effect of cycle configuration was developed. (2) A prototype SEDL absorption chiller with two-step E/A was also developed.

Patterns of circulating water were selected to maximize its cooling capacity.(3) The prototype performed at 106.1kW (30.2RT) in cooling capacity.

Chilled water of 7°C was obtained by using 88.7°C hot water, and its return temperature went down to 53.0°C.

(4) This prototype also could be driven in normal double-lift operation. 60°C hot water was used until 56°C and 7°C chilled water is produced.

(5) The simulation program appeared to have enough function and accuracy to predict the behaviour of SEDL absorption cooling cycle.

Through the development of SEDL chiller, following results are obtained.

This work is supported by New Energy and Industrial Technology Development Organization (NEDO), Japan.

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© Hitachi, Ltd. 2017. All rights reserved.

Tatsuo FujiiMay/17/2017

Hitachi, Ltd. Research & Development GroupThermal Fluidic Systems Research Department

END

Cycle Simulation and Prototyping of Single-Effect Double-Lift Absorption Chiller

19

[email protected]

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20© Hitachi, Ltd. 2017. All rights reserved.

Appendix A – Application image

Hot water network

Chilled water loopIndustrial waste heat, Power plant

SE/DL chillerHot water demand

Ø Wide temperature drop in hot water (i.e. 95 – 55 = 40 °C) reduces the hot water flow rate and pumping power of the system.

Gas-enginepower gen.

(CHP)

Ø Low temperature driven heat pump chillers are expected to be used in district heat, solar system and distributed energy systems.

Commercial demand

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21© Hitachi, Ltd. 2017. All rights reserved.

Appendix B – Comparison with forerunner’s work

Ø Our project aims at reduction of hot water outlet temperature, hereby increase the application of hot water driven absorption chillers.

Cycle scheme

Cooling water temp. in/out (°C)

Hot water temp.

(°C)

1009080706050

Project Düsseldorf

Project Berlin

ZAE Bayern, 1998 This work

SE/DL

ASHRAE Transactions 104 (1998): 1420

27/35

Present Product

SE

(1990’s~)

31/37 27/35 31/36.4

: inlet : outlet

SE: Single effectDL: Double lift

27/33

For Asia For Europe

51°COutlet

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22© Hitachi, Ltd. 2017. All rights reserved.

484950515253545556

94 95 96 97 98 99

100 101 102

Normal AHX*2 HHX *2 LHX *2 HHX *2LHX *2

HHX *2LHX *2AHX *2

Hot

wat

er te

mpe

ratu

re (T

HW-o

ut)

C)

Cap

acity

(QE)

, CO

P (%

)

Solution heat exchanger formation

QE COP THW-outTHW-in: 95°C, Chilled water in-out: 13-8°C

Appendix C – Effect of solution heat exchangers –

Ø Referring simulation results, we selected “HHXÍ2 and LHX Í2”.

C AG

AA

AHX

E1

E2

HG

LG

HHX

LHX

A1

A2

Refrigerant liquid

Refrigerant vapour

Page 24: Cycle Simulation and Prototyping of Single-Effect …hpc2017.org/wp-content/uploads/2017/06/o464.pdf · 2. Single-Effect Double-Lift ... Evaporator Auxiliary Generator Absorber Condenser