solar absorption refrigeration

8/11/2019 Solar Absorption Refrigeration

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Group Members

ASIF IQBAL 10-MC-28

HAMZA JAVED 10-MC-54 UBAID-UR-REHMAN 10-MC-56 ZIA MUHAMMAD 10-MC-58 SAAD HANIF 10-MC-60


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CONTENTS1. INTRODUCTION2. LITERATURE REVIEW3. MATERIALS AND METHODS

4. PRINCIPLE5. WORKING6. DESIGN AND CALCULATIONS7. RESULT AND DISCUSSION8. CONCLUSION9. REFERENCES


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INTRODUCTION


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REFRIGERATION Refrigeration is a process in which work is done to

move heat from one location to another.

The work of heat transport is traditionally driven by mechanical work.

Refrigeration has many applications:household refrigerators, industrial freezers, airconditioning, heat pumps etc.


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METHODS OF REFRIGERATION

There are two methods of refrigeration:

Vapour Compression Refrigeration Vapour Absorption Refrigeration


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TYPES OF ABSORPTION REFRIGERATION

Absorption machines are commercially available todayin two basic configurations.

LITHIUM BROMIDE/WATER Refrigeration CycleAbove 32F (primarily air conditioning), the cycle useslithium bromide as the absorbent and water as therefrigerant.

AMMONIA/WATER Refrigeration CycleBelow 32F, an ammonia/water cycle is employed withammonia as the refrigerant and water as the absorbent.


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LITERATURE REVIEW Absorption cooling was invented by the French scientist

Ferdinand in 1858. The original design used water and sulfuricacid.

Ali zadeh carried out theoretical study on design andoptimization of water lithium bromide refrigeration cycle.

Tyagi carried out the detailed study on aqua-ammonia VARsystem

Talbi and Agnew carried our energy analysis on single effectabsorption refrigeration cycle with lithium bromide water as theworking fluid pairs. The cycle collects free energy from theexhaust of diesel engine.


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MATERIALS AND METHODS


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EVAPORATOR

Heat energy is absorbed by the refrigerant vaporizingat low pressure and saturation temperature.

The low-pressure refrigerant vapour is drawn to the

absorber.


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ABSORBER

The concentrated absorbent is cooled and mixed with thelow-pressure refrigerant resulting in a weak solution. Thisweak solution is transferred to the generator to complete

the cycle.


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GENERATOR

Heating source Separation of the refrigerant

from the absorber The pure concentrated absorbent passes to the absorber vessel.The heat applied to the generator

also generates the high side pressure of the system.


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CONDENSER

Rejects heat from the refrigerant, causing therefrigerant to de-superheat and condense to liquidform.

The liquid refrigerant then passes to the evaporator.


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ABSORPTION REFRIGERATOR


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SOLAR GEYSER

It is a device using solar radiation to heat water. The solar water heaters employ the natural convection

phenomenon called thermo syphon , which results in hot water being lighter than cold water.

The water heated in water tubes rises through the solar collectorto enter storage tank , while the cold water at the bottom of the

tank flows in tubes creating continues circulation.


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REFRIGERANT Anhydrous ammonia is a clear, colorless liquid or gas, free from

visible impurities. It is at least 99.95 percent pure ammonia.

Boiling Point -28 F Vapor pressure at 0 F 16 psi Vapor pressure at 68 F 110 psi Vapor pressure at 100 F 198 psi


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PRINCIPLE


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PRINCIPLE

Dalton's Law of Partial PressuresThe total pressure of a mixture of gases is equal to thesum of the partial pressures of the component gases.

PressureTotal

= PressureGas 1

+ PressureGas 2

+

Pressure Gas 3 + ... Pressure Gas n


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THREE FLUIDS ABSORPTION SYSTEM

This type of refrigerator is also called Three-fluidsabsorption system . The three fluids used in this

system are:

1. AMMONIA

2. HYDROGEN3. WATER


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WORKING


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WORKING Strong ammonia chamber solution ready for boiling and

starting the cycle again.


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DESIGN AND CALCULATIONS


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Assumed for theoretical calculation Condenser pressure: 5 bar, Evaporator pressure: 2 bar, Capacity of refrigeration: 0.25 TR,


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DESIGN OF CONDENSER

1) Mass flow rate of NH 3 through Condenser (m r ): m r = Cooling load/ h 1 h2

= (0.25x3.5)/(1632.462-376.722) m r = 6.968 10 -4kg/s

2) Heat removed in condenser (Q C): QC = m r (h 1- h 2)

= 6.968 x 10^-4 x (1632.462-376.722) QC = 0.875kW.


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DESIGN OF CONDENSER We assume do=17.5mm di=16.5mm ho=16w/m.K hi=1833.76w/m.K K=17w/m.k Then U=15.85w/m.K

AS Q= [U*A*LMTD] A= DL Then L=Q/ (U* *d*LMTD)

L=0.21m


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DESIGN OF EVAPORATOR m f =6.968 10 -4kg/s Qe=m f *(h 4- h3)

=0.875KW

Temp. of air surrounding evaporator, Th i = 2 C Temp. of air after 1 min, Tc o = 3 C. Temp. of NH 3 liquid entering evaporator,Tc i =-18 C Temp. of NH 3 liquid leaving evaporator, Tc o=-15 C LMTD=4 C Overall heat transfer coefficient=U=19.59w/m.K Q= [U*A*LMTD]

L=0.22m


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DESIGN OF ABSORBER

ii) Heat rejected in absorber (Q a):Qa =1.31kw

Inlet temperature of water, Tc i = 23 C

Outlet temperature of water, Tc o = 25 C Temperature of NH 3 entering, Th i = 34 C Temperature of NH 3 leaving, Th o = 28 C LMTD=5.48 C U=21w/m.K Q = [ U*A*LMTD] L = 3.2m No. of turns=6


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DESIGN OF GENERATOR Original mass of the solutions are taken 15% more. Mass flow rate of weak solution entering into the generator from

absorber = 0.0015945* 1.15

= 0.001833 kg/s. Mass flow rate of strong solution going into the heat generator = 0.00186*1.15 = 0.00215kg/s Mass flow rate of water vapor leaving the generator = 0.00215-0.001833 = 0.0003163 kg/s. Total volume of vapor= m*specific volume Specific volume of vapor = 5.63 m 3/kg.


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DESIGN OF GENERATOR Total volume of vapor = 0.0003163*5.63

= 0.0017810 m 3/s. Total volume of strong solution = 0.00215* 0.0019

= 4.0861 * 10-6 m 3/s. Total volume of generator

= [volume of water vapor] +[volume of strong Solution]= 0.0017810+4.0861* 10-6= 1.7847*10-3 m 3/s.

Assuming 10% clearance

Volume generator = 1.983*10-3 m3

/s. But value = /4*dL /4*dL = 1.983*10-3 Therefore d= 8.75cm L=33cm


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COEFFICIENT OF PERFORMANCE

C.O.P=Heat absorbed in Evaporator Heat supplied in Generator

(C.O.P) MAX =(Te

TcT )( TgTcTg

) T

e=-16.5+273=256.5

Tc=44.5+273=317.5 Tg=60+273=333 C.O.P=0.195


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FAISALABAD LOCATION

1. Weather station FAISALABAD is at about31.42 0 N and 73.06 0E.

2. Height about 184m/603 feet above sees level.3. Region: Punjab4. Country: Pakistan5. Latitude: 31.4166667


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CLIMATE CONDITION FAISALABAD 24-hr average temperature

Thermal performance of Solar Geyser

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year

0

C 11.7 14.7 19.8 26.0 31.4 34.1 32.5 31.6 30.2 25.6 19.0 13.7 24.5

O

F 53.4 58.5 67.6 78.8 88.5 93.4 90.5 88.9 86.4 78.1 66.2 56.7 76.1

Time (hrs) Ambienttemp.

0C

Inlet temp.0C

Outlet temp.0C

Storagetemp.

0C 9:00 34.08 26.35 42.07 42.09

10:00 37.50 27.05 52.25 54.02 11:00 39.21 29.50 65.35 64.66 12:00 40.93 31.35 76.55 74.23 1:00 42.05 33.47 85.07 83.70 2:00 43.07 34.08 87.15 85.69 3:00 39.45 30.03 82.58 80.39

4:00 35.25 28.17 78.63 77.05


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RESULT AND DISCUSSION


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CONCLUSION


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Conclusion

Absorption system has a proven history of providinglow-cost reliable cooling and should continue to do so

in the future.Absorption systems can provide significant energysavings for a particular application.


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REFERENCES


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REFERENCES Lavanya et al, International journal of advanced engineering

research and studies. ASHRAE Hand Book 1951(Tables of specific volume of aqua

ammonia solutions) John A. Duffie, 1991. William A.Beckman. Solar Engineering

Of thermal Processes. John Wiley & sons. Inc. Staicovici M. D.,(1986)" An Autonomous Solar Ammonia-

Water Refrigeration System", Solar Energy, Volume 36, Issue 2,1986, Pages 115-124

V.F. TCHAIKOVSKY. And A.P. KUTEZSOV, Utilisation ofrefrigerant mixtures in refrigerating compression machinery, Air Conditioning And Refrigeration in india. Vol.4,1964.

solar absorption refrigeration

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