Absorption Refrigeration System, Ethanol-Water

1. Experimental Estimation ofExperimental Estimation ofExperimental Estimation ofExperimental Estimation of
EthonalEthonal--Water ofWater of PumplessPumpless
Ab ti R f i tAb ti R f i tAbsorption RefrigeratorAbsorption Refrigerator
Ass. Inst.Ass. Inst. AkeelAkeel Mohammed AliMohammed Ali MoradMorad
(Refrigeration and Air Conditioning Dept.)(Refrigeration and Air Conditioning Dept.)
ASHRAE memberASHRAE memberASHRAE memberASHRAE member

2. AbstractAbstract
Th b ti f i ti t i h t t d tTh b ti f i ti t i h t t d tThe absorption refrigeration system is heat operated system,The absorption refrigeration system is heat operated system,
which can make use of waste heat that rejected out of thewhich can make use of waste heat that rejected out of the
different thermal processes. It can also be operated using solar,different thermal processes. It can also be operated using solar,
geothermal and biomass energies The only part that usesgeothermal and biomass energies The only part that usesgeothermal, and biomass energies. The only part that usesgeothermal, and biomass energies. The only part that uses
electrical power in these systems is the circulating pump.electrical power in these systems is the circulating pump.
Eliminating this part needs different absorption cycle design.Eliminating this part needs different absorption cycle design.
To do this, heat driven vapor bubble pump is used.To do this, heat driven vapor bubble pump is used.p p pp p p
The bubble pump is a heated vertical tube that lifts fluid from aThe bubble pump is a heated vertical tube that lifts fluid from a
lower reservoir to a high reservoir as it is heated at the lowerlower reservoir to a high reservoir as it is heated at the lower
part where vapor bubbles are formed. The performance of thepart where vapor bubbles are formed. The performance of the
b bbl i bili lif h f i li id db bbl i bili lif h f i li id dbubble pump or its ability to lift up the amount of its liquid andbubble pump or its ability to lift up the amount of its liquid and
vapor with a minimum heat input is a function of its physicalvapor with a minimum heat input is a function of its physical
geometry, cycle pressure difference, and working fluidgeometry, cycle pressure difference, and working fluid
properties So the efficiency of the bubble pump dependsproperties So the efficiency of the bubble pump dependsproperties. So, the efficiency of the bubble pump dependsproperties. So, the efficiency of the bubble pump depends
upon the amount of vapor which lifted up across the bubbleupon the amount of vapor which lifted up across the bubble
pump to the total mixture.pump to the total mixture.
The aim of this project is to verification increasing the efficiencyThe aim of this project is to verification increasing the efficiencyThe aim of this project is to verification increasing the efficiencyThe aim of this project is to verification increasing the efficiency
of bubble pump to recirculation of mixture independent toof bubble pump to recirculation of mixture independent to
using Ethanolusing Ethanol--Water mixture.Water mixture.

3. IntroductionIntroduction
AA conventionalconventional absorptionabsorption refrigerationrefrigeration systemsystem isis runningrunning
primaryprimary onon heatheat energy,energy, butbut requiresrequires mechanicalmechanical energyenergy
toto circulatecirculate thethe absorbentabsorbent solutionsolution fromfrom thethe lowlow pressurepressuretoto circulatecirculate thethe absorbentabsorbent solutionsolution fromfrom thethe lowlow pressurepressure
absorberabsorber toto thethe highhigh pressurepressure generatorgenerator.. ItIt isis knownknown thatthat
aa bubblebubble pumppump cancan bebe replacereplace thethe solutionsolution pumppump forfor
llll i ii i dd d id i ll bb hhsmallsmall capacitiescapacities andand drivendriven onlyonly byby heatheat..
AA bubblebubble pumppump isis aa fluidfluid liftlift pumppump (i(i..ee.. AirAir oror VaporVapor liftlift
pump)pump) ItIt isis aa verticalvertical tubetube FigFig 11 thethe fluidfluid liftslifts upup inin thethepump)pump).. ItIt isis aa verticalvertical tubetube FigFig.. 11,, thethe fluidfluid liftslifts upup inin thethe
tubetube asas aa twotwo--phasephase flowflow patternpattern.. HeatHeat supplysupply oror airair
injectioninjection toto thethe fluidfluid atat thethe basebase ofof aa verticalvertical tubetube
createscreates bubblesbubbles therebythereby increasingincreasing thethe buoyancybuoyancy ofof thethecreatescreates bubbles,bubbles, therebythereby increasingincreasing thethe buoyancybuoyancy ofof thethe
fluidfluid causingcausing itit toto riserise throughthrough thethe verticalvertical tubetube.. Hence,Hence,
thethe importantimportant operatingoperating parametersparameters ofof thethe bubblebubble pumppump
areare tubetube diameter,diameter, length,length, submergencesubmergence ratio,ratio, andand heatheat
inputinput..

4. Experimental SetupExperimental Setup
TheThe aimaim ofof thethe experimentalexperimental testtest ofof vaporvapor bubblebubble pumppump isis toto
obtainobtain andand studystudy thethe actualactual relationshiprelationship ofof waterwater flowflow ratesrates
withwith varyingvarying heatheat inputinput toto validatevalidate thethe bubblebubble pumppumpwithwith varyingvarying heatheat inputinput toto validatevalidate thethe bubblebubble pumppump
mathematicalmathematical modelmodel thatthat isis developeddeveloped inin thethe presentpresent workwork
basedbased onon EthanolEthanol--WaterWater propertiesproperties..
TheThe ProposedProposed experimentalexperimental systemsystem performedperformed inin whichwhich somesome
ofof thethe parametersparameters affectingaffecting thethe bubblebubble pumppump performanceperformance
(tube(tube diametersdiameters andand submergencesubmergence ratios),ratios), werewere needneed toto(( gg ),),
changechange.. TheThe schematicschematic diagramdiagram ofof thethe experimentalexperimental setupsetup isis
shownshown inin FigFig..((11))..

5. Fig. 1Fig. 1
Separator
Ethanol vapor
flow meter
Condenser
p
Water flow
meter
Bubble
Reservoir
Cooling coil
Bubble
pump
Vapor
generator Electric
heater

6. ResultsResults
Lft TubeDifferent Length , D= 10 mm
2
1.6
1.8
L= 0.5 m
0.7
1
1
1.2
1.4
kg/min
1.34
0.6
0.8
1
Ml
0.2
0.4
0.25 0.35 0.45 0.55 0.65 0.75 0.85
H/L