Modified thermo-ecological optimization for refrigeration systems and an application for irreversible four-temperature-level absorption refrigerator

ORIGINAL RESEARCH Open Access

Modified thermo-ecological optimization forrefrigeration systems and an application forirreversible four-temperature-level absorptionrefrigeratorEmin Acikkalp

Abstract

In this study, a modified ecological function is presented for four-temperature-level absorption refrigerators, and anabsorption refrigerator has been optimized using this function. An equivalent system was initially identified,followed by the application of the first and second laws of thermodynamics. Next, the optimization results wereinterpreted. The results of the optimization process, optimum point of xH, xR, aH, and aR, were defined as 0.87, 0.58,2.41, 0.25, respectively. In addition to that, the effects of xH, xR, aH, aR, Ta, Tc, Te, and Tg were shown according toexergy destruction, ecological function, coefficient of performance, and cooling load. As a result, it was understoodthat especially the xH, parameter, and the generator temperatures are the variables of the system that requirespecial attention because, at some points, they cause that generator and absorber transfer heat in the oppositedirection they need to do.

Keywords: Absorption system, Optimization, Irreversibility, Refrigeration, Ecological

BackgroundAbsorption refrigerators may provide a cooling effectusing various energy resources in the system such aswaste heat and renewable energy. However, the factorthat makes them attractive is not only the diversity ofenergy resources used, but also their economic aspectsand minimal pollution effect on the environment. Inaddition to these, it was demonstrated that absorptionrefrigerators are more economic when they are inte-grated with the combined heat and power stations.Finite-time thermodynamics have been used for theoptimization of thermal systems since the 1970s. Theecological criterion [1] suggested by Angulo-Brown isanother optimization method. This criterion is shown asE:

¼W:

�TL σ:

for the finite-time Carnot machines. Here,TL is the cold reservoir temperature, and σ is the entropyproduction of the system. However, Yan demonstrated thatshowing the ecological criterion as E

:

¼W:

�T0 σ:would be

more reasonable [2]. Here, T0 is the ambient temperature.

There are many studies in the literature for theoptimization of irreversible absorption refrigerators.Bhardwaj et al. optimized absorption refrigerators usingfinite-time thermodynamics [3,4]. Huang et al. examinedthe surface area, coefficient of performance (COP), andecological criteria for the irreversible four-temperature-levelabsorption refrigerator and used an ecological functionbased on energy analysis [5]. The ecological function they

used is E: � ¼ QL

: �ϕCTL σ:. Here, ϕC is the Carnot COP of

the system, TL is the cold reservoir temperature, QL:is the

cooling load, and σ:is the entropy production. Chen offered

models for the optimization of absorption refrigerators,heat pumps, and cooling machines [6,7]. Sun et al. exam-ined the optimization of the relation between heating loadand entropy production of the internal heating heat ex-changer [8]. Chen et al. offered a model for the analysis offour-temperature-level absorption refrigerator cycles [9].Chen and Yan made an optimization on the irreversible ab-sorption heat exchangers for ecological criterion [10].Yan and Chen [11] and Yan and Lin [12] optimized thethree-temperature-level absorption cycles for the ecologicalcriterion on the basis of energy and exergy output of the

Correspondence: [email protected] of Mechanical and Manufacturing Engineering, EngineeringFaculty, Bilecik S.E. University, Bilecik, Turkey

© 2013 Acikkalp; licensee Springer. This is an Open Access article distributed under the terms of the Creative CommonsAttribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproductionin any medium, provided the original work is properly cited.

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irreversible Carnot cycles. Fathi et al. offered amodel for irreversible and solar absorption cooling[13]. In addition to these, except for the ones statedhere, there are many performance optimization stud-ies for absorption refrigerators [14-17]. In addition,new optimization methods called ‘advanced exergy-based analysis methods’ [18,19] or ‘exergy-entropyrelationship’ [20] of the system can be investigatedfor the future studies. Contrary to other studies inwhich cooling load is the only evaluation criteria,this study aimed to provide maximum cooling load,minimum operation input, and minimum entropyproduction in the system. Due to this reason, amodified ecological function was presented. Consid-ering the energy requirements of the world, the pur-pose of this study is to contribute to the moreeffective operation of absorption refrigerators by pre-senting a modified ecological function.

MethodsIn this study, a four-temperature-level absorptionrefrigerator was optimized using a modified ecologicalfunction, and the results were presented. A vaporabsorption refrigeration system consists of four com-ponents as generator, absorber, evaporator, and con-denser. Working fluid in the system is made of arefrigerant and a solution that absorbs refrigerant. Re-frigerant vapor comes from the evaporator and goes tothe absorber, and it is absorbed in a liquid. The liquidis sent to the generator and is boiled out of the solu-tion, taking the generator’s heat reservoir. It is sent tothe condenser and becomes a rejected heat to the en-vironment. Finally, working fluid comes back to theevaporator, and the cycle is completed. The system isthe general absorption refrigerator (seen in Figure 1).Temperatures of heat reservoirs are TA, TC, TE, and TG

in absorber, condenser, evaporator, and generator,respectively. Ta, Tc, Te, and Tg are working fluid tem-peratures in absorber, condenser, evaporator, andgenerator, respectively. In Figure 2, an equivalentsystem is defined. In the equivalent system, theabsorber-generator assembly can be considered as heatengine part, and similarly, condenser-evaporator partcan be considered as refrigerator part.

Thermodynamic analysis of systemThermodynamic analysis and optimization wereestablished for the equivalent system, and previous for-mulas offered by Chen et al. were used in the calcula-tions [21]. The ambient temperature was assumed as300 K.

Thermodynamic analysis of the absorber-generatorassembly (heat engine part)According to the first law of thermodynamics,

Q:

GE � Q:

AB �W:

¼ 0: ð1Þ

Here, Q:

GE (heat input from the generator heat source)

and Q:

AB (heat output to the absorber heat sink) may bedefined as

Q:

GE ¼ αAGE TG � Tg� �

and Q:

AB¼ βAAB Ta � TAð Þ: ð2Þ

According to the second law of thermodynamics,

Q:

GE

Tg� Q

:

AE

Ta≤ 0 or

Q:

AB

Ta¼ IH

Q:

GE

Tg: ð3Þ

Here, IH is the internal irreversible parameter forabsorber-generator assembly. IH > 0 for the irreversiblecycles, and IH = 0 for the reversible cycles. Workingfluid temperature ratio (xH), heat transfer surface arearatio (aH), and total heat transfer surface area (AT,H) forthe absorber-generator assembly can be defined as fol-lowing:

Figure 1 Generalized four-temperature-absorption heat pumpsystem [3].

Acikkalp International Journal of Energy and Environmental Engineering 2013, 4:20 Page 2 of 9http://www.journal-ijeee.com/content/4/1/20

xH ¼ Ta

Tg; aH ¼ AAB

AGE; and AT ;H

¼ AGE þ AAB are defined: ð4Þ

Tg, Ta, and Q:

GE can be defined using Equations (1) to(3):

Tg ¼ IHαTGxH þ aHβTA

xH aHβþ IHαð Þ ð5Þ

Ta ¼ IHαTGxH þ βaHTA

βaH þ IHαð Þ ð6Þ

Q:

GE ¼αAT ;H

1þ aH

βaH TGxH � TAð ÞxH βaH þ IHαð Þ

� �: ð7Þ

Thermodynamic analysis of the condenser-evaporatorassembly (refrigerator part)According to the first law of thermodynamics,

Q:

CO � Q:

EV �W: ¼ 0: ð8Þ

Here, Q:

CO (heat rejection from the condenser) and

Q:

EV (heat input to the evaporator) are

Q:

CO ¼ μACO Tc � TCð Þ and Q:

EV¼ θAEV TE � Teð Þ: ð9Þ

According to the second law of thermodynamics,

Here, IR is the internal irreversible parameter forcondenser-evaporator assembly. IR > 0 for the irreversiblecycles, and IR = 0 for the reversible cycles. Workingfluid temperature ratio (xR), heat transfer surface arearatio (aR), and total heat transfer surface area (AT,R)for the condenser-evaporator assembly can be definedas following:

xR ¼ Te

Tc

aR ¼ ACO

AEVAT ;R ¼ ACO þ AEV:

ð11Þ

Tc, Tg, Q:

CO , and Q:

EV can be defined using Equations(8) to (11):

Tc ¼ TCμxRaR þ θTEIRxR θIR þ μaRð Þ ð12Þ

Te ¼ TEθIR þ μxRaRTC

μaR þ θIRð13Þ

Q:CO ¼

μAT ;RaR1þ aR

θIR TE � TCxRð ÞxR θIR þ μaRð Þ

� �ð14Þ

Q:

EV ¼θAT ;R

1þ aR

μaR TE � xRTCð ÞμaR þ θIR

� �ð15Þ

Optimum ecological function of the systemThe modified ecological function, including the values ofmaximum cooling load in the absorption cooling system,maximum power output for the heat engine, and max-imum energy destruction of the system is defined below:

E: ¼ Q

:

EV

� �þ Q:

GE

� �� Q:

AB

� �� To

Q:

AB

TA� Q

:

GE

TGþ Q

:

CO

TC� Q

:

EV

TE

� �:

ð16ÞSubstituting (3) to (15) in (16) and setting Equation

(16)'s derivation to zero with respect to aH ∂ E:

∂aH¼ 0

� �,

the value for which the optimum heat exchanger areawas detected for the assembly of the absorber-generatorand which corresponds to such area is as below:

ao;H ¼ffiffiffiffiffiffiffiffiIHαβ

s: ð17Þ

Similarly, the optimum heat rate of the operationfluids is detected by decreasing the derivative of the eco-

logical function to xH ∂E:

∂xH¼ 0

� �for the assembly of the

Figure 2 An equivalent system for generalizedfour-temperature-absorption heat pump system [3].

Q:

CO

Tc� Q

:

EV

Te≤ 0 or

Q:

CO

Tc¼ IR

Q:

EV

Teð10Þ


absorber-generator, and the value corresponding to thisrate is as below:

xo;H ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiTATa TG þ Toð ÞTGIHTg TA þ Toð Þ

s: ð18Þ

By applying the same calculations for the assembly of

the condenser-evaporator aR ∂ E:

∂aR¼ 0

� �,

xR ∂ E:

∂xR¼ 0

� �values are detected, and these values are

as below,

ao;R ¼ffiffiffiffiffiffiffiIRθμ

sð19Þ

xo;R ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

TEIRTeTo

TCTc TE þ Toð Þ

s: ð20Þ

Substituting (17) to (20) in (16), the optimized eco-logical function is calculated as

E:

o ¼

μθAT ;rðIRTcTETo þ TCTe TE þ Toð Þ� 2

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiIRTETeToTCTc TE þ Toð Þp ÞffiffiffiffiffiffiffiθIR

p þ ffiffiffiμ

p� �2TETC

þ

αAT ;Hβ

�IHTaTG TA þ Toð Þ þ TATg TG þ Toð Þ

� 2ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiIHTgTGTaTA TG þ Toð Þ TA þ Toð Þp �ffiffiffiβ

p þ ffiffiffiffiffiffiffiffiαIH

p� �2TATG

ð21Þ

Optimum COP of the systemThe COP of the absorption system can be defined as

φ ¼ Q:

EV

Q:

GE

: ð22Þ

The COP of the system is described by substitutingEquations (7) and (15) into (22)

φ ¼ Q:

EV

Q:

GE

¼θAT ;RaR1þaR

μaR TE�xRTCð ÞμaRþθIR

� �αAT ;H

1þaHβaH TGxH�TAð ÞxH βaHþIHαð Þ

� � : ð23Þ

The optimized COP value is calculated as below, byputting the values in their places in Equation (23):

φEC ¼

AT ;Rμθffiffiffiβ

p þ ffiffiffiα

p ffiffiffiffiffiIH

p� �2 ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiTATa TG þ Toð Þp

TcffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiIRTETeTo

p � Te

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiTcTC TE þ Toð Þp� �

AT ;hαβffiffiffiμ

p þ ffiffiffiffiffiffiffiθIR

p� �2 ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiTcTC TE þ Toð Þp

TaffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiIHTGTg TA þ Toð Þp � Tg

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiTaTA TG þ Toð Þp� �

ð24Þ

Optimum cooling load of the systemThe optimum cooling load of the system is calculatedby putting the optimized values in their places in Equation(15):

Q:

EV;EC ¼AT ;Rμθ Te

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiTCTc TE þ Toð Þp � Tc

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiIRTETeTo

p� �ffiffiffiμ

p þ ffiffiffiffiffiffiffiθIR

p� �2 ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiTCTc TE þ Toð Þp :

ð25Þ

Results and discussionThis section presents an implementation for the absorption.The performance characteristics used for the numericalcalculations are given in Table 1. The calculated optimumparameters for the system are listed in Table 2.The ecological function and exergy destruction of the

absorption cooling system and its change according toCOP aH are given in Figure 3. Here, it can be seen that asthe COP value aH increases, it decreases logarithmically,

Table 2 Calculated optimum parameters for the system

Data Unit Value

aH,o Dimensionless 2.41

aR,o Dimensionless 0.25

xH,o Dimensionless 0.87

xR,o Dimensionless 0.58

Table 1 Fixed values for cycle

Data Unit Value

αa kW m−2 K−1 2.30

βa kW m−2 K−1 0.4

μa kW m−2 K−1 3.265

θa kW m−2 K−1 0.195

AAB m2 60

ACO m2 20

AEV m2 150

AGE m2 45

IH kW K−1 1.05

IR kW K−1 1.05

Ta K 290

Tc K 360

Te K 250

Tg K 354

TA K 315

TC K 300

TE K 285

TG K 365aData from [22].


and it decreases to the value of 2.6 for the optimum aHvalue. However, this value is quite high for the currentlyused absorption cooling systems. In addition, it can be seenthat the aH value is not very effective for the exergy destruc-tion. While the aH value changes between 0.1 and 03, theincrease seen for the exergy destruction is 3 kW.The ecological function, exergy destruction, and cooling

load of the absorption cooling system and its changeaccording to COP aR are given in Figure 4. Here, it can be

seen that the ecological function, exergy destruction, andcooling load increase logarithmically until optimum pointwith the increase of the aR parameter.In Figure 5, the change of absorption cooling system

according to xH is evaluated for the ecological function,exergy destruction, and COP. For the values of xH lowerthan 0.82, it can be seen that the generator radiates heatto the environment instead of removing heat from theenvironment, and the absorber removes heat from the

150

180

210

240

270

300

330

360

390

420

450

480

510

540

570

600

E (kW)

ExD (kW)

COP

aH

E, E

xD

0.1

aH,o

= 2.41

2

4

6

8

10

12

14

16

CO

P

0.5 1.0 1.5 2.0 2.5 3.0

Figure 3 Effect of aH (aR,E = 0.25, xH,E = 0.87, xR,E = 0.58) on the system. E, ecological function; ExD, exergy destruction; Φ, COP.

80

120

160

200

240

280

320

360

400

440

480

520

560

600

640

680

720

760

800

E (kW)

QEV (kW)

ExD (kW)

COP

aR

E, E

xD, Q

EV

0.01 0.05 0.10 0.15 0.20 0.25 0.30.0

0.5

1.0

1.5

2.0

2.5

3.0

CO

PaR,o

= 0.25

Figure 4 Effect of aR (aH,E = 2.41, xH,E = 0.87, xR,E = 0.58) on the system. E, ecological function; ExD, exergy destruction; Φ, COP; QE, cooling load.


environment instead of radiating heat to the environ-ment. In other words, the heat machine part consumespower instead of producing power, and the systembecomes unusable with these values. The COP of thesystem decreases with the increase of xH, and it requiresan approximate value of 2.6 for the optimum xH. Exergydestruction also increases with the increase of xH, and

an increase of 300 kW is seen with an exergy destructionin xH with a value of 0.2.In Figure 6, the change of the absorption cooling system

according to xR is evaluated for the ecological function,exergy destruction, cooling load, and COP. The COPof the system decreases with the increase of xR, andit approximately takes a value of 2.4 for the optimum

-100

0

100

200

300

400

500

600

700

800

0.950.90x

H

E, E

xD

E (kW)

ExD (kW)

COP

0.85 1.0

xH,o

= 0.87

0

1

2

3

4

5

6

7

CO

P

Figure 5 Effect of xH (aH,E = 2.41, aR,E = 0.25, xR,E = 0.58) on the system. E, ecological function; ExD, exergy destruction; Φ, COP.

-100000

-80000

-60000

-40000

-20000

0

20000

40000

60000

80000

100000

E (kW)

QEV(kW)

ExD (kW)

COP

xR.o

= 0.58

0

2

4

6

8

10

12

14

16

18

0.1

xR

E, E

xD, Q

EV

CO

P

0.2 0.3 0.4 0.5 0.6

0.8

0.05

Figure 6 Effect of xR (aH,E = 2.41, aR,E = 0.25, xH,E = 0.87) on the system. E, ecological function; ExD, exergy destruction; Φ, COP; QE,cooling load.


xR. Exergy destruction and ecological function changedrastically together with xR. The cooling load de-creases with the increase of the value of xR. Whilethe cooling capacity is 4917.49 kW when the xR value is0.05, it decreases to 339.317 kW when the xR value is 0.65.The effects of the absorber temperature on the sys-

tem are given in Figure 7. As the absorber temperature

increases, it can be seen that while the ecological functionand exergy destruction values decrease, the COP valueincreases.The effect of the generator temperature on the absorption

cooling system is given in Figure 8. For temperatures lowerthan 335 K, the generator radiates heat to the environmentinstead of removing heat from the environment, so it

200 220 240 260 280 300200

250

300

350

400

450

500

550

600

650

E (kW)

ExD (kW)

COP

Ta (K)

E, E

xD

0

1

2

3

4

5

CO

P

Figure 7 Effect Ta (aH,E = 2.41, aR,E = 0.25, xH,E = 0.87, xR,E = 0.58) on the system. E, ecological function; ExD, exergy destruction; Φ, COP.

340 345 350 355 360200

250

300

350

400

450

500

550

E (kW)

ExD (kW)

COP

Tg (K)

E, E

xD

0

2

4

6

8

10

12

14

16

18

CO

P

Figure 8 Effect of Tg (aH,E = 2.41, aR,E = 0.25, xH,E = 0.87, xR,E = 0.58) on the system. E, ecological function; ExD, exergy destruction; Φ, COP.


cannot be used in lower temperatures. In addition tothis, while the increase of the generator temperatureincreases ecological function and exergy destruction, itdecreases the COP.The effect of a condenser on the system is given in

Figure 9. As seen here, as the condenser temperatureincreases, the ecological function, exergy destruction,cooling load, and COP values decrease.

In Figure 10, COP, ecological function, exergy de-struction, and cooling load increase linearly with theincrease of evaporator temperature.

ConclusionsThe optimization of four-temperature-level irreversibleabsorption refrigerator was researched for modifiedecological function in this study. By this method, it was

300 320 340 360 380 4000

200

400

600

800

1000

1200

1400

E (kW)

ExD (kW)

QEV (kW)

COP

TC

E, E

xD, Q

EV

0

1

2

3

4

CO

P

Figure 9 Effect of Tc (aH,E = 2.41, aR,E = 0.25, xH,E = 0.87, xR,E = 0.58) on the system. E, ecological function; ExD, exergy destruction; Φ, COP;QE, cooling load.

220 230 240 250 260 270 2800

200

400

600

800

1000

1200

1400

E (kW)

ExD (kW)

QEV (kW)

COP

Te (K)

E, E

xD, Q

EV

0

1

2

3

4

CO

P

Figure 10 Effect of Te (aH,E = 2.41, aR,E = 0.25, xH,E = 0.87, xR,E = 0.58) on the system. E, ecological function; ExD exergy destruction; Φ, COP.


attempted to establish a balance between the coolingload, the load supplied to the system, and entropy pro-duction. The effects of aH, aR, xH, and xR parametersand operation fluid temperatures on the system werestudied, and the results were shown in Figures 3, 4, 5,6, 7, 8, 9, and 10. Considering these results, the criteriathat should be observed in designing an absorptioncooling cycle were determined, and the parameters thatshould be observed were shown. This study will hopefullybe a model for absorption refrigerator designs.

AbbreviationsNomenclaturea, ratio of heat exchanger surface areas; A, heat exchangersurface area (m2); COP, coefficient of performance; _E ,ecological function (kW); ExD, exergy destruction (kW);I, internal irreversibility parameter; m, ratio of environ-ment temperature to absorber; n, ratio of environmenttemperature to generator; _Q, heat (kW); T, temperature (K);_W , work (kW); x, ratio of temperatures; y, ratio of environ-ment temperature to condenser; z, ratio of environmenttemperature to evaporator.

Subscripts0, environment; 1, inlet, 2, outlet; a, absorber working fluidtemperature; A, mean absorber heat source temperature;AB, evaporator; c, condenser working fluid temperature; C,mean condenser heat source temperature; CO, condenser;e, evaporator working fluid temperature; EC, ecological; E,mean evaporator heat source temperature; EV, evaporator;g, generator working fluid temperature; G, mean generatorheat source temperature; GE, generator; H, heat enginepart; R, refrigerator part; o, optimum; T, total.

Greek lettersα, total heat conductance of generator (kW m−2 K−1); β,total heat conductance of absorber (kW m−2 K−1); Φ,coefficient of performance of system (COP); μ, total heatconductance of condenser (kW m−2 K−1); θ, total heatconductance of evaporator (kW m−2 K−1); _σ , entropygeneration (kW K−1).

Competing interestsThe authors declare that they have no competing interests.

Authors’ informationEA is a research assistant in the Faculty of Engineering at Bilecik S.E.University. He received his BSc and MSc in the Engineering and ArchitectureFaculty in Eskisehir Osmangazi University in 2000 and 2004, respectively.

AcknowledgmentsThe authors would like to express their sincere gratitude to the editor(Professor Farivar Fazelpour), anonymous reviewers for their invaluablecomments and suggestions which substantially improved the overall qualityof the manuscript, and to the language editor Sherlyn C Machica.

Received: 9 January 2013 Accepted: 20 March 2013Published: 18 April 2013

References1. Angulo-Brown, F: An ecological optimization criterion for finite-time heat

engines. J. Appl. Phys. 69(11), 7465–7469 (1991)2. Yan, Z: Comment on “Ecological optimization criterion for finite-time

heat-engines”. J. Appl. Phys. 73(7), 3583 (1993)3. Bhardwaj, PK, Kaushik, SC, Jain, S: Finite time optimization of an

endoreversible and irreversible vapour absorption refrigeration system.Energ. Convers. Manage. 44(7), 1131–1144 (2003)

4. Bhardwaj, PK, Kaushik, SC, Jain, S: General performance characteristics of anirreversible vapour absorption refrigeration system using finite timethermodynamic approach. Int. J. Ther. Sci. 44(2), 189–196 (2005)

5. Huang, Y, Sun, D, Kang, Y: Performance optimization for an irreversiblefour-temperature-level absorption heat pump. Int. J. Ther. Sci.47(4), 7479–7485 (2008)

6. Chen, J: The optimum performance characteristics of a four-temperature-levelirreversible absorption refrigerator at maximum specific cooling load. J. Phys.D: Appl. Phys. 32(23), 3085–3910 (1999)

7. Chen, J: Optimal performance analysis of irreversible cycles used as heatpumps and refrigerators. J. Phys. D: Appl. Phys. 30(4), 582–587 (1997)

8. Sun, F, Qin, X, Chen, L, Wu, C: Optimization between heating load andentropy-production rate for endoreversible absorption heat-transformers.Appl. Energy. 81(4), 434–448 (2005)

9. Chen, L, Zheng, T, Sun, F, Wu, C: Irreversible four-temperature-levelabsorption refrigerator. Sol. Energy 80(3), 347–360 (2006)

10. Chen, T, Yan, Z: An ecological optimization criterion for a class of irreversibleabsorption heat transformers. J. Phys. D: Appl. Phys. 31(9), 1078–1082 (1998)

11. Yan, Z, Chen, T: Optimization of the rate of exergy output for anendoreversible Carnot refrigerator. J. Phys. D: Appl. Phys.29(12), 3017–3021 (1996)

12. Yan, Z, Lin, G: Ecological optimization criterion for an irreversible three-heat-source refrigerator. Appl. Energy. 66(3), 213–224 (2000)

13. Fathi, R, Guemimi, C, Ouaskit, S: An irreversible thermodynamic model forsolar absorption refrigerator. Renew. Energ. 29(8), 1349–1365 (2004)

14. Gordon, JM, Ng, KC: Cool Thermodynamics. Cambridge InternationalScience, Cambridge (2000)

15. Ng, KC, Chua, HT, Han, Q, Kashiwagi, T, Akisawa, A, Tsurusawa, T:Thermodynamic modeling of absorption chiller and comparison withexperiments. Heat Transfer Eng 20(2), 42–51 (1999)

16. Ng, KC, Wang, XL: Thermodynamic methods for performance analysis ofchillers. P. I. Mech. Eng. E-J. Pro. 219(2), 109–116 (2005)

17. Gordon, JM, Ng, KC: Predictive and diagnostic aspects of a universalthermodynamic models for chillers. Int. J. Heat Mass Tran.38(5), 807–818 (1995)

18. Morosuk, T, Tsatsaronis, G, Boyano, A, Gantiva, C: Advanced exergy-basedanalyses applied to a system including LNG regasification and electricitygeneration. Int. J. Energy Environ. Eng. 3(1), 1–9 (2012)

19. Tsatsaronis, G, Morosuk, T: Advanced exergetic analysis of a refrigerationsystem for liquefaction of natural gas. Int. J. Energy Environ. Eng.1(1), 1–17 (2010)

20. Palazzo, P: Thermal and mechanical aspect of entropy-exergy relationship.Int. J. Energy Environ. Eng. 3(4), 1–10 (2012)

21. Chen, L, Xiaoqin, Z, Sun, F, Wu, C: Exergy-based ecological optimization fora generalized irreversible Carnot heat-pump. Appl. Energy.84(1), 78–88 (2007)

22. Florides, GA, Kalogirou, SA, Tassou, SA, Wrobel, LC: Design and constructionof a LiBr–water absorption machine. Energy Convers. Manage44(15), 2483–2508 (2003)

doi:10.1186/2251-6832-4-20Cite this article as: Acikkalp: Modified thermo-ecological optimizationfor refrigeration systems and an application for irreversible four-temperature-level absorption refrigerator. International Journal of Energyand Environmental Engineering 2013 4:20.


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Modified thermo-ecological optimization for refrigeration systems and an application for irreversible four-temperature-level absorption refrigerator