DESIGNANDCONSTRUCTIONOFAMINIATURECYLINDRICALPARABOLICTROUGHSOLARCONCENTRATOR

1SAIPHANINDRADINESHKAKARLAMUDI,2BHARATHREDDYKALSANI,3KESHAVJHA,4PRANAYKUMARGANDLA,5MANOJMALAE,6SONUGUPTA

DepartmentofMechanicalEngineering,JNTUHCollegeofengineering,Kukatpally,Hyderabad,India,Email:Kakarlamudi.dinesh111@gmail.com

ABSTRACT

Overthelastfewdecades,therehavebeensignificantchangesinthewaypeopleusetheworldsenergyresources.Therehasbeenanincreasingeffortfromgovernments,industryandacademicinstitutionstofindalternativesourcesofenergyandtoimprove energy efficiency. This, plus an ever growing pressure from different sectors of society to reduce carbon dioxideemissions, has motivates the development of emerging technologies to reduce the dependency on fossil fuels and theoptimizationofexistingsystemsinordertominimizeenergyconsumption.Solarenergyisoneofthealternativeenergiesthathasvastpotential.Itisestimatedthattheearthreceivesapproximately1000W/m2amountofsolarirradiationinaday.

Therearetwowaystoproduceelectricityfromthesun.Firstisbyusingtheconcentratingsolarthermalsystem.Thisisdoneby focusing theheat from the sun toproduce steam.The steamwilldroveagenerator toproduceelectricity.This typeofconfigurationisnormallyemployedinsolarpowerplants.Theotherwayofgeneratingelectricityisthroughaphotovoltaic(PV)cell.Thistechnologywillconvertthesunlightdirectlyintoelectricity.Someoftheapplicationsofsolarenergyarepowerplants,Homes, Commercial use, Ventilation system, Power pump, Swimming pools, Solar lighting, Solar cars andRemoteapplications. These are the few above applications where the use of Solar Energy can be used. So, there is a need toconcentrateSolarEnergy.

Here,weareconstructingacylindricalparabolicsolarconcentratorforconcentratingsolarenergy.Theconcentratedenergyisusedforheatingthewaterandthusanalyzingtheinletandoutlettemperaturesofwater.Asolarconcentratorisadevicethatusesparabolicmirrorstoredirectandconcentratethesunsraysontoasmallfocalpoint.Theyareusedinmanydifferentapplicationswheresolarthermalenergyisinvolved.

IndexTerms:Solarenergy,Solarconcentrator,Parabolicconcentrator

1.SOLARCONCENTRATOR

Asolar concentratoris a device that uses parabolicmirrorstoredirectandconcentratethesunsraysontoasmall focal point. They are used in many differentapplicationswheresolarthermalenergyisinvolved.Solar concentrators can also be used in photovoltaicsolar applications to concentrate the sun's energy ontothe solar panel itself. This allows the panel to createmuchmoreenergyandbemoreefficientasitisexposedto a much larger amount of sunlight than it normallywould be without the collector to redirect the raysdirectlyonthepanel.Solarconcentratorsarealsousedinsolarthermalpowerstationsaround the globe, and they are the mosteffective way of producing electricity through solarenergy.Asolarthermalcollectorutilizesalargearrayofsolar concentrators or mirrors to redirect andconcentrate the suns energy onto a focal point. Thisfocal point has reach temperatures in excess of 2000degreesCelsius.In a solar thermal power station, the solar thermalenergygeneratedatthefocalpointisthentransferredto

water to make it boil and create steam. This steam isthen used to run asteam turbineto create electricity.Solar concentrated energy seems to be the way of thefuture,asitispossibletocreatemuchmoreenergyinasmallerspacethanwithphotovoltaicsolarpower.1.1BACKGROUND

The idea behind a concentrating solar collector is tominimizetheheatlossesassociatedwithsolarcollection.In many instances it is desirable to deliver energy athigher temperatures than thosepossiblewith flatplatesolar collectors. In this case, a parabolic mirrorconcentrates incident solar irradiation onto a muchsmaller receiver area, greatly decreasing heat loss andmaximizingtheavailableenergyfromthesun.Therearemanydifferenttypesofconcentratingsolarcollectorsinusetoday.Concentratorscanbereflectingorrefracting,cylindrical, spherical, parabolic, and they can becontinuousorsegmented.Receiverscanbeconvex, flat,cylindrical,coveredoruncovered.One important factor in the analysis of solarconcentrators is the concentration ratio. Theconcentrationratio isdefinedastheratiooftheareaofthe aperture of the concentrator to the area of the

SAI PHANINDRA DINESH KAKARLAMUDI et al. Volume 3 Issue 4: 2015

Citation: 10.2348/ijset07150946 Impact Factor- 3.25

ISSN (O): 2348-4098 ISSN (P): 2395-4752

International Journal of Science, Engineering and Technology- www.ijset.in 946

receiverthatisreflecteduponbytheconcentrator.Thisis in essence the heart of a solar concentrator. Solartracking is also necessary for efficient use ofconcentratingcollectors. Withouttrackingthecollectorbecomes almost useless except for a very short timeperiod once a day. Large scale concentrators today useautomatedtrackingsystemsthatcantrackthesunonabiaxialpath.1.2CLASSIFICATIONOFSOLARCONCENTRATOR

Thedifferent concentrating concentrators are generallyclassifiedasunder: Focusing and NonFocusing type: Whether the

Collectorfocusesthesolarradiationontheabsorberorjustdivertsit.Focusingtypecollectorsarefurtherclassified in line focusing and point focusingcollector.

Tracking and NonTracking type: Whether theCollector is provided with Tracking Mechanism sothat itcanfollowthesunor isofFixedOrientation.Tracking type is further classified as Single axistracking andDouble axis tracking. Tracking can beintermittent (daily or weekly tracking) orContinuousTracking.

Concentrating Ratio achievable: Concentrationratioachievablecanbebetween1(limitingvalueforFlat Plate Collector) to 10,000 (Parabolic DishCollector). Concentration ratio also approximatelydetermines the operating temperature of thecollector. In this article the collector that can becompared with Compound Parabolic Concentratorarediscussed.Theyare:

CylindricalParabolicConcentrator: It is conventionalimaging collector. It focuses the solar energy on a line,through which water flows. The aperture areas varyfrom16m2.Theconcentrationratioisintherangeof10 80. Temperature up to 400oC can be obtained. Asimpleworkingmodelisshowninfigure.

Figure1:CylindricalParabolicConcentrator

ParabolicDishCollector: This is similar to cylindricalparabolicconcentratorexceptherethefocusingispointfocusing instead of line focusing. Hence a very high

concentration ratio is achieved. The deliverytemperature created by this collector is the highestamongallthecollectorsaround600C.Figuredescribesthe working of Parabolic Dish Collector. A moresophisticatedparaboliccollectortroughcanbedesigned,that avoids the need to track the sun altogether, bycombining two parabolas together, to form the"CompoundParabolicTroughSolarCollector."Whenthisisdone,thecofocalpointthenbecomesacofocalline.Ifa coolant filled pipe solar energy absorber pipe, or atubularevacuatedtubesolarenergyabsorbertubeiscolocatedatthecofocalline,therewillthenbeamaximumof concentrated solar energy delivered and transferredtotheenergyabsorbertube!Suchsolarcollectorsdonotneedtracking,andrequireonlyoccasionalseasonangleadjustments(severaltimesayear)arerequiredtokeepthe aperture perpendicular to the noonday sun, to themaintainmaximumpoweroutput.

Figure2:ParabolicDishConcentrator

CompoundParabolicConcentrator:Byselectingnonimagingopticswecan thus avoid the need to keep the collector aperturepointed at the sun. Instead, we can collect andconcentrate Solar Energy from multiple directionsseparatelyoratonce.Sowhilethesunmovesacrossthesky, we can still accept and concentrate the SolarThermal Energy all day using a properly designedcompound Parabolic Trough Concentrating SolarCollector coupled with Evacuated (vacuum) tube Solarenergy Capture Tubes. Using this type of collector, theoutput energy of a Solar Energy Capture Tube can beincreased by a factor of 4 6 times using a stationarysolarcollector.

Figure3: CompoundParabolicConcentrator

SAI PHANINDRA DINESH KAKARLAMUDI et al. Volume 3 Issue 4: 2015

Citation: 10.2348/ijset07150946 Impact Factor- 3.25

ISSN (O): 2348-4098 ISSN (P): 2395-4752

International Journal of Science, Engineering and Technology- www.ijset.in 947

FresnelConcentrator: Fresnel lens function is similarto the conventional lens, by refracting the rays andfocusing them at one focal point. It generally has twosections; a flat upper surface and a back surface thatemployscanted facets.The facet isanapproximationofthecurvatureofalens

Figure4:FresnelConcentrator

Hyperboloid Concentrator: The general design of ahyperboloid concentrator is shown in Figure 3. Itconsists of two hyperbolic sections, AB and AB. Thehyperboloid concentrator can be produces by rotatingthe two dimensional design along its symmetrical axis.The diameters of the entrance and exit aperture arelabeledasd1andd2respectively.Iftheinsidewallofthehyperbolicprofileisconsideredasamirror,thesunraysenteringtheconcentratorfromAAwillbereflectedandfocused to theexitapertureBB. Theadvantageof thisconcentrator is that it is very compact, since onlytruncatedversionof theconcentratorneeds tobeused.Because of this factor, it ismainly used as a secondaryconcentrator. An example of application of thisconcentratorhasbeendevelopedbySolFocus,withtheintentionofreducingthecostofsolarelectricity.

Figure5:HyperboloidConcentrator

DielectricTotally InternallyReflectingConcentrator(DTIRC):ThefirstconceptofDTIRCwasintroducedbyNingetal.in 1987. This new class of optical element has thecapability to achieve concentrations close to thetheoretical maximum limits. There are two ways toproduce the DTIRC; maximum concentration methodand phase conserving method. Although both methodswillcreatealmostidenticalstructure,thefirsttechniqueoffers slightly higher concentration and thereforemoresuitableforsolarapplication. DTIRCconsistsofthreeparts; a curved front surface, a totally internallyreflecting side profile and an exit aperture