Thermal Performance of Low Cost Packed Bed Thermal Energy Storage Systems for Space Heating and Crop Drying Applications in the Rural Areas

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1 Volue, Issue (0 0-0 ISSN 7-8 Interntionl Journl o Advne Reserh nd Innovtion Therl Perorne o Low ost Pked Bed Therl Energy Storge Systes or Spe Heting nd rop Drying Applitions in the Rurl Ares R S Mishr Deprtent o Mehnil & Prodution Engineering, Delhi Tehnologil University, New Delhi, Indi Artile Ino Artile history: Reeived Noveber 0 Reeived in revised or 0 Noveber 0 Aepted 0 Noveber 0 Avilble online Deeber 0 Keywords Low ost solr syste, Therl energy storge systes, Flow through the porous edi, Solr therl syste design Abstrt Low grde therl energy is oten required in the griulturl produts, the onventionl uels ost oonly used re diesel, petrol, biodiesel, NG, LPG, eletriity, wood, gro wste et. re vilble very ostly dy by dy nd re getting in the rurl res. The lterntive is to use the solr energy therl storge systes bsed on wter is ir required s bsi oponents in the low grde therl energy utiliztion. A siple therl nlysis or open nd lose loop pked bed olletor u storge syste hs been rried out to study the perorne o the syste using dierent type o therl energy storge terils suh s roks, pebbles, glss piee, stone piees nd ired brik. The eet o vrious preter o pked bed, dieter o pked bed, porosity nd ss low rte on the voluetri het trnser o-eiient, het lux, eiieny o the syste hs been studied in detils nd tie dependent periodi therl odel ws developed. It ws observed tht ire brik gives better therl energy storge eet thn other storge teril nd hene it is reoended or open loop nd lose loop solr rop drying systes in the rurl res. Introdution Solr energy is interittent in nture. For vriety o pplition the therl energy ight be ost required when there is no sun rdition. The need o storge o sun energy is thereore desirble or vrious pplitions during o sun shine hours nd loudy seson. This energy storge y be in or o sensible het o solid nd liquid ediu, s het o usion in heil energy o produt nd in reversible heil retion. The hoie o storge edi depends upon the nture o the proess. For wter heting the energy storges in sensible het o stored is logil while or the se o ir heting olletor u storge syste in the or o sensible or ltent het hs been suggested suh s sensible het in the pebble bed het exhngers. A pked bed o rok pile or pebble bed storge unit uses the het pity o the bed o loosely pked prtiulte teril to store energy. A luid, usully ir is irulted thought to dd or reove energy. A vriety orresponding Author, E-il ddress: proessor-rsishr@yhoo.o.in All rights reserved: o solid y be used suh s rok, ired briks, stone piees, glss piees et. being the ost widely used therl energy storge energy terils due to low ost, esy vilble in the rurl re. In this pper the study o the eet o the storge edi onneted to n eiient solr energy olletor using trix bsorbers solr ir heter u pked bed storge syste using dierent energy storge teril nd perorne o the syste in ters tie dependent therl eiieny, tie dependent energy lux hs been lulted.. Pked Be D Enery Storge Unit onneted To A Solr olleter In A Open And lose Loop yles The studies on the rok bed storge syste sop r del with het trnser or pressure drop in the storge syste. Aongst these re the works o Lo et l (98, lose (9 Hughes (97, hndr(98, Frber(98, Mishr (99 et. heting nd ooling o pked bed hve lso been studied by Shun (99, Dukes(97 nd Lupin (9. They studied the pressure drop ross the 0

2 Volue, Issue (0 0-0 ISSN 7-8 Interntionl Journl o Advne Reserh nd Innovtion pked beds. The experientl study by hndr et l (98 del with het trnser hrteristis o the rok bed nd lso disusses the pressure drop ross suh systes. Mishr (99 dels with the tie dependent therl odel o open nd lose loop solr energy systes using rok beds. Solr olletor u storge syste is ore expensive due to ost o olletor nd ost o therl energy storge unit. In this pper we onsidered solr trix ir heting bsorber u storge units o esily vilble therl energy storge teril in the rurl/reote res or rops drying pplitions nd developed tie dependent therl odel to study its perorne. The developed odel is the odiition o Shunn (99 odel by onsidering the eet o ondution in the therl energy storge terils. The nlytil expressions or vrious preters hve been obtined expliitly. Forer work o (Kuhn et l (978 in this diretion ws done by nuerilly solving Shunn odel with inite deerene tehnique. The odel dev eloped in this pper hs been tested orresponding to dt vilble or solr intensity nd bient teperture or ritil dy o, d T h T X t X t v T K e dx, Where T (x,t is the lol ir teperture & di/dx is the het energy ttined by the sures. The irst ter in the eqution represents the het retined in the bed while seond ter is or the het trnser ro the. d X, t p dx The (- sign in eqution ( is due to the t tht hot ir loses het to the pked bed. orreltions relting voluetri het trnser oeiient to the bed hrteristis into the luid low onditions re given by G.O.G.Lo (98, Frber & ourtier (98 & hndr (98 s ollow: hv 700 /. A d 0.70 ( W /( Eliinting bed teperture ro eqs ( - (, one obtins third order dierentil eqs. In ters o ir teperture Where ( h y v ( h v /( / K / A h /(( v / A, I /( e to p p K e T K ( New Delhi (Indi types lites. The eet o vrious preters suh s prtile size porosity et. on the therl perorne (in ters o tie vrition o eiieny, useul energy lux hve been rried out or dierent energy storge terils.. Therl Anlysis o Pked Bed olletor u Storge Systes Using Low ost Absorber Mterils The nlysis o pked bed energy storge systes hve been perored under ollowing ode o opertion.. Dierent trix & luid tepertures In the onigurtion o the storge syste, pked bed hs been onneted into porous ir heter, in whih the perorne o the syste depends upon olletor preters nd storge preters. The energy blne eqution or the bed teperture over the pked bed segent o thikness dx n be written s X, t dq X, t dt p dx ( hot ir to the roks. The third ter represents the energy stored by the pked bed. The rok teperture is however relted to ir teperture by the ollowing expression 9 ( n Tn( n (( I tn ( n / U L Rerrnging nd seprting the eqs. Into tie dependent & tie independent prts one n get solution o dierentil eqs. The ollowing boundry onditions re used K dt ( d, t / dx h ( d, t T dt h T X, t X, t ( v T i K y ( I 7 8 ( n /( exp(( A U tn in ( n ( p ( n in p dt o T F ' /( ( in (0, t / dx l p h h p o p / K (0, t T e T 0

3 Volue, Issue (0 0-0 ISSN 7-8 Interntionl Journl o Advne Reserh nd Innovtion Assuing periodi nture o solr intensity, bient teperture, bed teperture & luid d T The rbitrry onstnts,,,,, nd n be deterined ro the ollowing set o boundry onditions. Applition o boundry onditions in eqs. (- yield the ollowing, X trixes or tie independent prt & tie dependent prts. The pked bed teril teperture & luid teperture n be obtined by substituting x=d in equ. ( nd equ. ( in equ. (. Results And Disussion o ( x / dx d To ( x / dx dt o ( x / dx T o ( x I Vlues o preter hve been used or nueril oputtion to vlidte proposed therl odel tken ro Mishr (99, 9. The vlues o olletor outlet teperture hve been lulted beuse it depends upon the eiieny o olletor u storge unit nd inidents o the rdition on the olletor. The outlet teperture vrition oh the storge units with ss low rte o ir hve been lulted long with orresponding vrition o therl eiieny nd useul energy lux. It ws observed tht the eet o inresing the prtile size on the voluetri het trnser o-eiient between the prtile nd ir long with teperture o prtiles, the het trnser dereses with the inresing storge size prtile eeting the bed teperture lso. Siilrly inresing he vlue o porosity eet the ooling eet o ediu i.e. the teperture o ir oing out the storge keeps on inresing porosity. The teperture distribution o the storge teril up to thikness o 0, it ws observed tht bed teperture rein onstnt whih tepertures, Rerrnging eq. ( we get ollowing third order dierentil eqs. it drops suddenly due to size o prtile nd the sping between the prtiles. The eets o porosity o the storge edi eet the therl perorne o therl energy systes onsiderbly. It is thereore obvious tht the prtile size nd the porosity o the prtile is kept to iniu possible. One hs to however blne it ginst inresing pressure losses nd hene the n power requireents. Tble ( shows the vrition o prtile teperture orresponding to hourly vrition o the solr lux nd bient or typil dy. It ws observed tht prtile n be heted ore thn twenty two degree entigrde thn bove bient teperture. The tie vrition o therl energy storge teril with lowing ir teperture with tie long with solr lux shown in the tbles ( - respetively. The tie vrition o useul energy lux nd therl eiieny with tie or dierent therl energy storge teril re shown in the tbles (- nd igs. (- respetively. It ws observed tht ire brik is best teril oe therl sensible energy storge pked bed.. onlusions to ( d To ( x / dx d Tn ( x / dx 7dT n ( x / dx 8T n ( x 9I The solution o bove eqs (, re expressed in the ollowing nner. T ( Re l K K p n dt dt o exp( X ( exp( X Re l T n ( exp( X T ( exp( X ( d, t / dx (0, t / dx h h h exp( X exp( X exp( X ( d, t T o (0, t T T exp( X y exp( X exp( X y exp( X y exp ( X exp( X y exp ( X ( exp ( X exp( int ( exp ( X exp( int The therl odel ws developed in this pper or inding therl perorne o trix olletor u storge systes. Following onlusions re drwn;. Pebble bed nd ire brik gives better therl energy storge eet thn other therl energy storge terils or open loop nd lose loop solr rop drying systes in the rurl nd reote res.. seond therl energy storge teril is blk pinted broken glss piees or spe heting nd rop drying pplitions in rurl res. tn 07

4 Volue, Issue (0 0-0 ISSN 7-8 Interntionl Journl o Advne Reserh nd Innovtion Tble: (. Vrition o teperture using therl energy storge terils (pebble nd glss piees, rok bed nd bient teperture with tie Tie (Hr. PEBBLE Fluid Tep ( GLASS PIEE Fluid Tep ( ROK 7 AM... Fluid Tep ( Tble: (b. Vrition o teperture using therl energy storge terils (brik nd ork nd bient teperture with tie Tie (Hr. BRIK Fluid Tep ( ORK Fluid Tep ( Abient Tep ( 7 AM Tble: (. Vrition o vrious therl energy storge terils (pebble nd glss piees tepertures nd bient teperture with tie Tie Abient PEBBLE GLASS PIEES (Hr. Tep ( Tep ( Tep ( 7 AM Tble: (b. Vrition o vrious therl energy storge terils (brik, rok nd ork tepertures nd bient teperture with tie Tie ROK BRIK ORK (Hr. Tep ( Tep ( Tep ( 7 AM

5 Volue, Issue (0 0-0 ISSN 7-8 Interntionl Journl o Advne Reserh nd Innovtion Tble: (. Vrition o therl energy eiieny o sensible het storge terils (pebble, glss piees nd roks with tie Tie PEBBLE GLASS PIEES ROK (Hr. E. ( % E. ( % E. ( % 7AM Tble: (b. Vrition o vrious therl energy eiieny o sensible het storge terils (brik, ork nd rok with tie Tie BRIK ORK ROK (Hr. E. ( % E. ( % E. ( % 7AM Tble: (. Vrition o het lux o vrious therl energy storge terils (Brik nd ork nd solr lux with tie Tie BRIK ORK Solr Flux (Hr. Useul Flux (W/ Useul Flux (W/ (W/ 7AM Tble: (b. Vrition o het lux o vrious therl energy storge terils (pebble, glss piees nd roks with tie Tie PEBBLE GLASS PIEES (Hr. Useul Flux(W/ Useul Flux(W/ ROK Useul Flux (W/ 7AM

6 Volue, Issue (0 0-0 ISSN 7-8 Interntionl Journl o Advne Reserh nd Innovtion Reerenes [] Dunkle RV, Rndoly pked prtile bed regenertor nd evportive oolers, Trns. Inst. o Engg. (Austrli Pge 7, 97 [] Lo, GOG, Unstedy stte het trnser between ir nd loose solids, Journls o Industril nd Engg heistry, 0 Pge 0, 98 [] R. S. Mishr, Design, developent nd tehnoeonoi evlution o hybrid solr ir heting u storge syste or spe heting nd rop drying, proeeding, eight, ntionl onerene o ehnil engineers, University o Roorkee, Pge -, 99 [] R. S. Mishr, Evlution o therl perorne o ventilting Trobe wll or porous nd nonporous Ninth, Ntionl onerene on ehnil engineering, IIT Knpur, Pge 7-8, 99 [] R. S. Mishr, Therl perorne o therl energy storge rok bed systes, interntionl onerene on dvnes in ehnil nd industril engineering, University o Roorkee, Pge -, 997 [] R. S. Mishr, Evlution o therl perorne o low ost rok bed therl energy storge syste or spe heting nd rop drying, Interntionl onerene on, Reserh nd Developent (Vision - st entury, Pge -, 999 [7] Shunn, Het trnser in liquid lowing through porous pris, Journl o het trnser, Frnkin Institute, Vol. 0,Pge 0, 99 0

a) Read over steps (1)- (4) below and sketch the path of the cycle on a P V plot on the graph below. Label all appropriate points.

a) Read over steps (1)- (4) below and sketch the path of the cycle on a P V plot on the graph below. Label all appropriate points. Prole 3: Crnot Cyle of n Idel Gs In this prole, the strting pressure P nd volue of n idel gs in stte, re given he rtio R = / > of the volues of the sttes nd is given Finlly onstnt γ = 5/3 is given You