ROAD TO CLIMATE FRIENDLY CHILLERS

Hydrocarbons & Absorption Chillers Systems: Development & Potential

Dr. Alaa Olama

Sept. 2010 , Cairo, Egypt

CONTENTS:

1- Hydrocarbon fired Absorption Chiller & Heat ratio

2- Difference between HR (COP) Abs. & COP V.C.

3- How did H.R (COP) improve dramatically.

4- Conclusion

1- Hydrocarbon Fired Absorption Chiller & Heat Ratio

ＣＯＰ (LP) ＝（ Refrigeration capacity ／（ Gas Low calorific value ＊ Gas consumption ）

ＣＯＰ (HP) ＝（ Refrigeration capacity ／（ Gas High calorific value ＊ Gas consumption ）

Definition of COP (HR) of Absorption Chillers

2- Difference between HR (COP) Abs. & (COP) V.C.

Overall efficiency of a power station:

S Type of Power Stations Percentage (%)

1 Best combined cycleSteam turbines carry the base load & gas turbines carry the variable load (peak load)

55

2 Steam cycle 40

3 Simple cycle 30-35

4 Transmission Losses 10

* Efficiency at Refrigeration plant boundary becomes 25 to 50 %

Comparing chillers efficiencies:

COP mvc 4 5 6

Station & transmission efficiency

25 30 35 50 25 30 35 50 25 30 35 50

COP abs 1 1.2 1.4 2 1.25 1.5 1.75 2.5 1.5 1.8 2.1 3

3- How did H.R (COP) improve dramatically

History of absorption chiller-heater

History of development for Gas direct fired absorption chiller

2005.22005.2Kyoto ProtocolKyoto Protocol

００ .. ７５７５ ０ .80 ０ .93 ～ 0.96 1.07 1.1

1.2

1.3

1.351.35

1.6 以上

H.R (COP) Improvement

Ratio of energy-saving

Low calorificvalue based COP

High calorificvalue based COP

30 energy-saving％ 1.18 1.0726 energy-saving％ 1.12 1.01

39 enegy-saving％ 1.36 1.22

32 energy-saving％ 1.22 1.1035 enegy-saving％ 1.28 1.15

42 enegy-saving％ 1.43 1.2845 enegy-saving％ 1.45 1.35

Key technology to improve the efficiency

3.Dual absorptionDual evaporation

4.Condensed refrigerantheat-exchanger

1.Improved solutionheat-exchanger

2.RefrigerantCooler

5.High performanceheat transfer tube

RCD

6.Exhaustheat-exchanger

RFD

7.Larger Heat transferarea on ABS. EVP.

8-Efficiency improvedon High stage GEN.

RED

Internal piping flow of RFD （ chiller ）

1- Improvement on efficiency of solution heat-exchanger

Shell & Tube typeheat-exchanger

• Solution heat-exchanger

High temp

Low temp.

Plate heat-exchanger

☆☆ AdvantageAdvantage

・　・　 Better heat transfer Better heat transfer performance compared to performance compared to S&TS&T

◎◎More compactMore compact

・　・　 Less solution retainedLess solution retained

☆☆ AdvantageAdvantage

・　・　 Better heat transfer Better heat transfer performance compared to performance compared to S&TS&T

◎◎More compactMore compact

・　・　 Less solution retainedLess solution retained

Key technology of improvement

2- Refrigerant cooler

↓

33℃

Key technology of improvement

Cooling down the refrigerant back from condenser, to reduce the load on Generator, to get better efficiency

Cooling down the refrigerant back from condenser, to reduce the load on Generator, to get better efficiency

Ref. cooler

EVP. (9 )℃

38℃

ABS.

Cooling W

CONDS.

Refrigerant

37℃

32℃

36.5℃

低温再生器

凝縮器

SP RP

SSPH

冷却水

35.5℃

72.3℃7.0℃

32.0℃A1=54.1%

冷水

15.0℃

37.0℃

11.1℃

【低圧】

【高圧】

再生器へ

蒸発器

蒸発器

吸収器

吸収器

Upper stage ：Low pressure in ABS. / EVP.Lower stage ： High pressure in ABS. / EVP.

☆☆AdvantageAdvantageBigger concentration difference of solution, by separating ABS. & EVP. to 2 stages

Enable to reduce circulating flow

Less heating calorie at Less heating calorie at Generator,Generator,thus better efficiencythus better efficiency

Less heating calorie at Less heating calorie at Generator,Generator,thus better efficiencythus better efficiency

3- Dual Absorption, Dual Evaporation Cycle

Key technology of improvement

4- Condensed refrigerant heat-exchanger

Key technology of improvement

Weak solution

Condenser （ 38℃ ）

Low temp. H-exchanger

Low stage GEN.

High temp. H-exchanger

S.P.

Heat recovery on High High temp. Refrigerant back temp. Refrigerant back from low GEN. and from low GEN. and weak solution, weak solution, to get better efficiency

Heat recovery on High High temp. Refrigerant back temp. Refrigerant back from low GEN. and from low GEN. and weak solution, weak solution, to get better efficiency

44℃

Con

den

sedrefrigeran

t

Condensed refrigerantCondensed refrigerantheat-Exchangerheat-Exchanger

90℃Heat from Low GEN.⇒Steam from High GEN.

78℃

36℃

5- High Performance heat transfer tube

Key technology of improvement

Exhaust

Natural Gas

Air supply20℃

High GEN.

The gas consumption reduced by pre-heating pre-heating the air supply to the the air supply to the Burner.Burner.

The gas consumption reduced by pre-heating pre-heating the air supply to the the air supply to the Burner.Burner.

6- Exhaust heat-exchanger（ Air pre-heater ）

Key technology of improvement

165℃

75℃

155℃

Air Pre-Air Pre-heaterheater

Key technology of improvement

7- Larger Heat transfer area on ABS. EVP.

Key technology of improvement

8- Efficiency improved on High stage GEN.

Improved solution heat-Improved solution heat-exchangerexchanger

ExhaustExhaustheat-exchangerheat-exchanger

increased KA increased KA value, on CND. value, on CND. ABS.ABS.

Refrigerant Refrigerant coolercooler

COP1.22

COP1.00

Solution flow Solution flow regulationregulation

RED

Improved solutionImproved solutionheat-exchangerheat-exchanger

+0.085

+0.015

RFD

+0.04 +0.015

+0.02

Dual ABS. / Dual ABS. / EVA.EVA.

+0.02

Large head of chilled Large head of chilled water water （（ Δ8℃Δ8℃ ））

Condensed Condensed ref. heat-ref. heat-exchangerexchanger

+0.05

＋

+0.035

Efficiency Efficiency improved High improved High

GEN.GEN.

COPCOP1.291.29

Designed based on COP1.29 COP1.29 machine

COPCOP1.351.35

ExhaustExhaustheat-exchangerheat-exchanger

+0.06

Reached COP1.35 COP1.35 with Exhaust heat-Exhaust heat-exchangerexchanger

Key technology of improvement

Improvement of COP by each technology

4- Conclusions

Conclusions:-

1- When comparing The overall thermal efficiencies ,it is important to compare the

efficiency of mechanical vapour compression systems (electric chillers) to the

efficiencies of vapour compression systems ( absorption chillers) , starting at the

boundary of supply to the power station(natural gas ) and the boundary of supply of

natural gas at the absorption chillers burner, otherwise the comparison cannot be

fair.

2- When this is done ,the difference in efficiencies is then quite close , taking into

consideration that few power stations in Egypt have high thermal efficiencies.

3- Therefore the use of natural gas in large central air conditioning projects is

economically sound since the saving in investment cost for power plant is

considerable.

(1)

Conclusions(Cont.):-

4- Shaving electrical peak loads in summer can only be achieved by the use of

natural gas fired air conditioning system.

5- legislation exists in many countries that prohibit the use of electrical energy in air

conditioning over a certain refrigeration tonnages (over about 1000 TR) This is the

case in Japan , South Korea & lately the United Arab Emirates.

The aim of the legislation is to preserve electric power for applications where there

are not other alternative sources of energy .

(2)