Development of a New Heat Exchanger for the Super Cooling (HESC) to Enhance the Performance of the Heat Pump System for the Living Space by the Natural Energy

Development of a New Heat Exchanger for the Super Cooling (HESC) to Enhance the Performance of the

Heat Pump System for the Living Space by the Natural Energy

Song,Heon*

*2 1BMFA Nat ur alEne r gyDe ve l opme nt ( ar c hi l i e u@hot mai l . c om)

자연에너지를 이용한 생활공간 냉난방용 열펌프의 성능향상을 위한 과냉 촉진 신개념 열교환기(HESC) 개발

송 헌*

*2 1BMFA 자연에너지 개발( ar c hi l i e u@hot mai l . c om)

Abst r act

과냉 촉진을 위한 새로운 열교환기( HESC) 가 생활공간의 냉난방을 위한 공기-물 열펌프의 성능계수 향상을 위해 본 연구에서 개발되었으며 그 효과를 실험적으로 분석하였다.이 열교환기( HESC) 는 여러 단계의 셀과 튜 브로 구성되어 있으며,열펌프 시스템의 응축기와 증발기 사이에 장착되었다.실험 조건으로,외기온은 7° C에서 -17° C,입구 물 온도는 7∼10° C 그리고 제 2열전달매체로서 물의 질량 유동율은 시간당 100에서 300ℓ로 변화 를 주었다.본 실험에서 이 열교환기가 장착된 열펌프의 압축기에서의 냉매 입⋅출구 사이의 온도 차이는 열교환 기가 장착되지 않은 열펌프보다 15° C 높았다.이에 따라 이 열교환기가 장착된 열펌프 시스템은 외기온 -10° C 에서 COP가 0. 8증가하였다.따라서 이 공기-물 열펌프 시스템은 최근 한국에서 실용화되고 있는 고비용이 요구 되는 지열 열펌프 시스템을 대체하여 생활공간을 위한 냉난방 시스템으로서 중요한 역할을 할 수 있을 것으로 사료된다.

Ke ywor ds:과냉 촉진 열교환기( He a tExc ha nge rf o rt heSupe rCo o l i ng( HESC) ) ,생활공간( Li vi ngSpa c e ) ,자연에너지 ( Nat ur alEne r gy) ,공기-물 열펌프 시스템( Ai r -t o-Wat e rHe atPumpSys t e m) ,성능계수( COP) [논문] 한국태양에너지학회 논문집

Journal of the Korean Solar Energy Society

Vol. 31, No. 6, 2011 IS S N 1 5 9 8 - 6 4 1 1

투고일자 :2011년 9월 14일,심사일자 :2011년 9월 17일,게재확정일자 :2011년 12월 12일

교신저자 :송헌( ar chi l i eu@hot mai l . com)

Nomencl at ur e

Q˙

gain :heatgainofthenew system circuitwithHESC (㎉/hr) Q˙

EVA,gc :heatabsorbedfrom evaporatorinthegeneral circuitwithoutHESC (㎉/hr) Q˙

comp :powerconsumptionof compressor(㎉/hr) ΔQ˙

HESC :heatgainincreasedbythe HESC (㎉/hr)

Q˙

Loss :theotherheatlossfrom the heatpumpsystem (㎉/hr) qLoss :heatlossperunitmassof

refrigerant(㎉/㎏) G˙

0 :massflow rateofrefrigerant (㎏/hr)

Δh :enthalpydifferencebetween twoconditions(㎉/㎏) COPgain :COP ofnew circuitwith

HESC

COPgc :COP ofthegeneralcircuit withoutHESC

ΔCOPHESC :COP increasedbyHESC Ev.i :Inletofevaporator Ev.o :Outletofevaporator S.i :InletofshellinHESC or

By-pass

S.o :OutletofshellinHESC or By-pass

Cm.i :Inletofcompressor Cm.o :Outletofcompressor Cd.i :Inletofcondenser Cd.o :Outletofcondenser T.i :InletoftubeinHESC or

By-pass

T.o :OutletoftubeinHESC or By-pass

Ex.i :Inletofexpansionvalve Ex.o :Outletofexpansionvalve

1.I nt r oduct i on

Thehumanbe i ngshavebe e nf ac e dwi t h t hedoubl edi f f i c ul t i e soft hehi ghoi lpr i c e s

ande nvi r onme nt alpol l ut i onc aus e dby t he f os s i lf ue l .

I nor de rt os ol vet he s epr obl e ms ,al love r t hewor l dr e ne wabl ee ne r gypr oj e c t sar ei n pr ogr e s st ode ve l op t hes ys t e m us i ng t he al t e r nat i vee ne r gyr e s our c e s .

I n U. S. A.and Br az i l ,e t hanolde ve l ope d as a t r ans por tf ue lf r om c or n and s ugar c a nei soneoft hef a c t or st or a i s et hepr i c e s ofs ugarandani malf e e d.

I n Eur ope , J a pa n, and Sout h Kor e a , s c i e nt i s t sa r ei mme r s e di nr e al i z a t i onoft he wi ndpowe r ,s ol a rc e l l( phot ovol t a i cs ys t e m) s ys t e ms ,a ndge ot he r ma lhe a tpumps ys t e m, a nd e s pe c i a l l y t he Kor e a n Gove r nme nt pr opos e dt hena t i ona lpr ogr amsof" t hel ow c a r bon a nd hi gh gr e e n gr owt h" f or t he de ve l opme ntofr e ne wa bl ee ne r gy.

Eve n i f t he wi nd po we r a nd s o l a r c e l l s ys t e msc o ul dber e l a t i ve l ygo o dc o mpl e me nt s f o rt he na t ur a le ne r gy ut i l i z a t i o n,t he r e a r e s o medi f f i c ul t i e si nc o nve r t i ngt hes unr a ysi nt o t hec l e a na ndr e l i a bl ee ne r gy.Fo re xa mp l e ,t he e f f i c i e nc yo fs o l a rc e l li sl i mi t e dt o1 3 % a ndt he i ns t a l l a t i o nc o s to ft hes ys t e m i st o ohi gha s c o mpa r e d wi t h a i r -t o -wa t e r he a t pump s ys t e m.

I n ge ne r a l ,t h e e n e r gy s t o r a ge s ys t e m i s i ne vi t a b l e f o r t he s o l a r e ne r gy ut i l i z a t i o n . Fo r t un a t e l y,s o l a re ne r gyi ss t o r e da bu nd a nt l yi n t hea i r ,t h ee a r t ha n dt hewa t e r .Unf o r t una t e l y, ho we ve r ,t het e mp e r a t ur eva r i a t i o no ft hes o l a r e ne r gys t o r e di nt h ea i ra c c o r d i ngt ot h er e gi o ns a nds e a s o n si so neo ft het r o u b l e df a c t o r sf o rt h e r e a l i z a t i o no fs o l a re n e r gys ys t e ms .

I nc a s eo ft hea i r -t o -wa t e rh e a tp umps ys t e m

us i ngt hee ne r gys t o r e di nt hea mbi e nta i ra s

t hehe a ts o ur c e ,t hec o e f f i c i e nto fp e r f o r ma nc e

wo ul dr a pi dl yde c r e as ebe l ow -1 0° C oft he

Fi gur e1 .Ai r -t o-wat erheatpumpc i r c ui ti ns t al l edwi t hHESC andex per i ment alappar at us

ambi e ntai rt e mpe r at ur e .

I n t her e vi e w oft hel i t e r at ur e ,t os ol ve t he s epr obl e mss ol aras s i s t e dhe atpumpon ai rc ol l e c t or shasbe e nde ve l ope dai mi ngat maxi mi z i ng t hee f f i c i e nc y oft hes ol arai r c ol l e c t or ,aswe l lasmi ni mi z i ngde c r e as eof a i r -t o -wa t e rhe a tp umpp e r f o r ma nc ed uet ot he r a p i dd e c r e a s eo ft hea mbi e nta i rt e mp e r a t ur e ( Kar agi or gase tal . ,2 0 08 ) .

I n addi t i on,a ne w phot ovol t ai c / t he r mal he at pump s ys t e m havi ng a modi f i e d c ol l e c t or / e vapor at or has be e n de ve l ope d and nume r i c al l y s t udi e d t opr ovet hatt he he atout putoft hes ys t e m c oul dbeus e dt o pr ovi dedome s t i chotwat e rhe at i ngand/ or s pac e he at i ng ( I t o e tal . ,199 7,Xu e tal . , 20 09) .The r ear emanyc aus e sf ors e as onal pe r f or manc e de gr adat i on.I n t he he at i ng s e as on,pe r f or manc er e duc t i onsar ec aus e d by r e duc e d s ys t e m e f f i c i e nc y at l ow out door t e mpe r at ur e ,and f r os t i ng oft he

out doorc oi l . ( N. B. M.s t e f anuke tal ,1 990 ) I n t hi s s t udy,i n or de r t o s ol ve t he s e pr obl e ms ,t heHESC ( He atExc hange rf or Supe r -Cool i ng)wasde ve l ope dandadapt e d t ot heai r -t o-wat e rhe atpumps ys t e m and t he c har ac t e r i s t i c s ofpe r f or manc e oft hi s s ys t e m we r eanal yz e d.

2.Thecomposi t i onoft heai r -t o-wat er heatpump and anal ysi s oft he t her malener gybal ance

2. 1.Ai r - t o-wat erheatpumpci r cui t . The a i r -t o-wa t e r he a t pump c i r c ui t i s c ompo s e da ss ho wni nFi g.1 .I tc ons i s t e dof c ompr e s s or ,e va po r a t or ,HESC,c onde ns e r , t woe xpa ns i o nva l ve sa ndf o ur -wa yva l vet o c ha nget hedi r e c t i o noft her e f r i ge r a ntf l ow i nt hec i r c ui tf orhe a t i nga ndc o ol i ng.

I ti sdi f f e r e ntf r om t heal r e ady e xi s t e nt

he a t p ump c i r c ui t i n t ha t t he HESC wa s

Fi gur e2 ( a) .Conf i gur at i ondet ai l soft heHESC

i ns e r t e dbe t we e nt hec o nde ns e ra nde va p o r a t o r f o rt h ee xt e n s i o no ft h es u p e rh e a t i n ga n dc o o l i n g p r o c e s s .HESCi sc o mp o s e do fmul t i s t a ges he l l a ndt ube sa nds o l e no i dva l ve s .

2. 2.Descr i pt i on oft heHESC

I nor de rt opr e ve ntt heCOP de c r e as eof ai rs our c ehe atpumps ys t e m a tt hea mbi e nt t e mpe r at ur ebe l ow -1 0° C,t heHESC asa ne w he ate xc hange rwasde ve l ope di nt hi s s t udy.

As s hown i n Fi g. 3,t he COP c oul d be i nc r e as e dwi t ht hepa r tofs upe rc ool i ngand he a t i nge xt e nde dbyt heHESCi nc o n d e n s i n g p r o c e s s .I na d d i t i o n ,t h et e mpe r a t ur ede c r e as e oft hes e c ondwor ki ngf l ui daswat e rhe at e d t hr ought hec onde ns e rc oul dbec ont r ol l e d.

Thec o nf i gur a t i o nde t a i l so fHESCa ndTI C a ut o -c ont r o lf l o w c ha r tf o rt heo pe r a t i o nof HESC c o ul dbede s c r i be da sf ol l o ws :

( 1)Conf i gur at i onde t ai l soft heHESC Ass howni nFi g. 2( a) ,i nor de rt oc hange t he he ate xc hange ar e a aut omat i c al l y t he HESC was c ompos e d of3 s t age s oft he s he l landt ube st ypehe ate xc hange r .

I n or de rt oc ont r olt hef l ow di r e c t i onof t her e f r i ge r antaswor ki ngf l ui d,t wo3-way val ve s ,one2 -wa yval ve ,a ndby-pas swe r e i ns t al l e dont heHESC.

Andt oope r at et heHESC aut omat i c al l y, t heTI C aut o-c ont r olc i r c ui twasat t ac he d t ot heHESC.

( 2)Aut omat i cope r at i onoft heHESC Ass howni nFi g. 2( a) ,HESCi saki ndof s he l l -and-t ube he ate xc hange rwi t h t hr e e s he l lpas s and mul t i -t ube pas s ope r at i ng aut omat i c al l yasc ount e rf l ow mode .

As s hown i n Fi g. 2 ( b) ,t he r e f r i ge r ant f l owsc ont i nuous l y f r om t hec onde ns e rt o t hee vapor at ort hr ought hemul t i -t ubepas s .

On t he ot he r hand,i tf l ows f r om t he e vapor at ort o t hec ompr e s s ort hr ough t he s he l lpa s sa ndby-pa s s ,a ndt he nt hedi r e c t i o n of s he l lpas s c oul d be c hange d by t he c ont r ol( ope nandc l os e )ofV1,V2andV3.

The val ve s V1 ,V2 and V3 c oul d be

c ont r ol l e d by t he TI C aut o-c ont r olf l ow

c har tt oi nc r e as et hehe ate xc hangear e aof

t he HESC c ompos e d of 3 s t age s he at

e xc hange r .

Fi gur e2( b) .TI C aut o-c ont r olf l ow c har tf ort he HESC oper at i on.

The aut omat i c ope r at i on oft he HESC ac c or di ng t ot heambi e ntt e mpe r at ur ec an bede s c r i be dasf ol l ows :

I n c as e oft he ambi e ntt e mpe r at ur e of T

≥0 ° C,t her e f r i ge r anti nf l owsdi r e c t l y t ot hec ompr e s s ornotpas s i ngt heHESC.

I n c as e oft he ambi e ntt e mpe r at ur e of -5 ° C < T

≤0° C,t heval veV1i sope ne d t ot heby-pas sandc l os e dt ot hes he l lpas s ofH I I ,s ot her e f r i ge r antf l owsf r om t he e vapor at ort o t hec ompr e s s ort hr ough t he s he l lpas sofH I .Cons e que nt l y,t heHESC ope r at e sasonl yOne -s t ages he l l -and-t ube he ate xc hange r .

I n c as e oft he ambi e ntt e mpe r at ur e of -1 0 ° C<T

≤-5° C,t heval veV1i sope ne d t ot hes he l lpas sofH I Iandt heval veV2 i sope ne dt ot heby-pas s ,s ot her e f r i ge r ant f l ows f r om t he e vapor at or t o t he c ompr e s s ort hr ought wo-s t ages he l lpas s e s ofH IandH I I .

I nc as eoft heambi e ntt e mpe r at ur eof -15 ° C <T

≤-1 0° C,t heval veV1i s ope ne dt ot hes he l lpas sofH I I ,t heval ve

V2ope ne dt ot hes he l lpas sofH I I Iand val veV3ope ne dt ot hec ompr e s s or ,s ot he

Fi gur e3 .Theai r - t o- wat erhe atpu mpc y c l ei n s t al l edwi t h andwi t h ou tt heHESC ont h eR

p- hc h ar t

r e f r i ge r antf l owsf r om t hee vapor at ort ot he c ompr e s s or t hr ough t he 3-s t age s he l l pas s e sofH I ,H I I ,andH I I I .

Cons e que nt l y,t he HESC ope r at e s as a 3-s t ages he l l -and-t ubehe ate xc hange r .

Al loft he ope r at i ons me nt i one d above c oul dbec ont r ol l e dbyt heTI Caut o-c ont r ol f l ow c har tass howni nFi g. 2( b) .

( 3)Theai r -t o-wat e rhe atpumpc yc l eon t heR

p-hc har t

The he a tpump c yc l e i ns t a l l e d wi t h a nd wi t ho utt heHESCo nt heR

p-hc ha r ti sa s s ho wni nFi g. 3whe r et hedo t t e dl i ne①-②-

③-④ i st hee xi s t e nthe a tpumpc yc l ewi t ho ut t heHESC a ndt hes o l i dl i ne①' -②' -③' -④' i sne w a i r -t o -wa t e rhe a tpumpc yc l ei ns t a l l e d wi t ht heHESC.I nt hec o nde ns i ngpr o c e s so f

②-③,③-③'i sapa r to fs upe rc o o l i nga nd② -②'apa r to fs upe rhe a t i nge xt e nde dbyt he HESC.

2. 3.Heatbal ance and coef f i ci entof per f or mance( COP)

Thehe atbal anc eandCOPgai ne dbyt he

HESC on t hep-h di agr am ofhe atpump

c yc l ec oul dbee quat e dasf ol l ows .( Fi g.3)

( 1)He atbal anc eofhe atpumpi ns t al l e d wi t hHESC

 

  

  

 ∆ 

  

 

  

∆

 ∆

 ∆

 ∆

 





( 2)Coe f f i c i e ntofpe r f or manc e( COP) . - COP oft hene w t hehe atpumpc yc l e

i ns t al l e dwi t hHESC.



 

 ∆





  ∆

∆

 





  ∆

∆

 



∆

≅∆

∆

  ∆

∆

 ∆



I n t he e quat i on ( 1 ) ∼( 5) , Δ Q

and Δ COP

ar et hehe atgai ne dandCOP i nc r e as e dbyHESC,r e s pe c t i ve l y.

( 3)Thee f f e c toft heHESC ont heCOP As s hown i n t he e quat i ons ( 1) ∼( 5 ) ,i t waspos s i bl et oanal yz et hatt hehe atgai n andCOPoft hehe atpumps ys t e m c oul dbe i nc r e as e d by t he HESC i ns t al l e d be t we e n t hee vapor at orandt hec onde ns e r( Fi g. 1 ) . 3.Ex per i ment alequi pmentandmet hod

I n or de r t o anal yz e e xpe r i me nt al l y t he

c oe f f i c i e ntofpe r f or manc e( COP)oft hehe at pumps ys t e m i ns t al l e dwi t ht heHESC,t he e xpe r i me nt ale qui pme ntandvar i abl ef ac t or s a r epr ovi de da ss howni nFi g. 4andTabl e1 .

3. 1.Exper i ment alequi pment

Fi gur e4.Ex per i ment alequi pmentofheatpumps y s t em ( 3 PS) .

Thec i r c ui toft hea i r -t o-wat e rhe a tpump

s ys t e m and t he e xpe r i me nt al e qui pme nt

we r e c ompos e d as s hown i n Fi g.1 .15

t he r moc oupl e s ( TM-B t ype )we r e f i xe d t o

me as ur et het e mpe r at ur e satt hei nl e tand

out l e tofr e f r i ge r antand wat e rc i r c ui tas

s hown i n Fi g.1.Al loft het e mpe r at ur e s

s e ns e dbyt he r moc oupl e sc oul dber e c or de d

aut omat i c al l y on t hehybr i dr e c or de r ( Type

8H12 ,made by NEC s an-e ii ns t .Lt d i n

J APAN) . ( Fi g. 4)A wat e rf l ow me t e rwas

s e tupi nt hewat e rc i r c ui tt ome as ur et he

wat e r mas s f l ow r at e .The s uc t i on and

di s c har gepr e s s ur eoft hes c r ol lc ompr e s s or

was obs e r ve d by i ns t al l i ng hi gh and l ow

pr e s s ur egauge si nc i r c ui t .Toobs e r vet he

phas ec hanges t at eofr e f r i ge r ant ,5s i ght

gl as s e s we r e e qui ppe d i n t he r e f r i ge r ant

c i r c ui ta ndt ome a s ur et hepo we rc o ns umpt i o n

o ft hes c r o l lt ypec o mpr e s s o ro f3 PSe mpl o ye d

Var i abl e s I t e ms

Ambi e ntai r t e mp. ( ℃)

Wat e ri nl e t t e mp. ( ℃)

Wat e rf l ow r at e( l / h)

Re f r i ge r ant l ow,hi gh

pr e s s ur e ( ㎏/ ㎠)

Me as ur i ngi t e ms Te s ti nt e r val

HESC -14 ∼4 7 ∼1 0 1 0 0∼30 0 3, 1 8 Te mpe r at ur eof1 5 poi nt si nt hewat e r

andr e f r i ge r ant c i r c ui t El e c t r i cpowe r

c ons umpt i on

3 0mi n.

-17 ∼7 7 ∼1 0 1 0 0∼30 0 3, 1 8

By-pas s -14 ∼4 7 ∼1 0 1 0 0∼30 0 3, 2 0 -17 ∼7 7 ∼1 0 1 0 0∼30 0 3, 2 0

Tabl e1 .Combi nat i onofv ar i abl esandmeas ur i ngi t ems

i nt hi ss ys t e m,t hewat tme t e r ( VI P,V3t ype madei nI t al y)ast hee ne r gyanal yz e rwas e mpl oye d.

3. 2.Exper i ment almet hod

Toanal yz et hec oe f f i c i e ntofpe r f or manc e ( COP) of t he ai r -t o-wat e r he at pump s ys t e m,t hevar i abl e sandme as ur i ngi t e ms c oul dbec ombi ne dass howni nTabl e1.

4.Resul t sanddi scussi on

4. 1.TheHESC ef f ectont hei nl etand out l ett emper at ur e ofr ef r i ger ant ci r cul at i ngi nt hemai noft heheat pumpci r cui t .

Fi gu r e5 .I n l e tan dou t l etr ef r i ge r an tt empe r a t ur eofmai nof t h eh e atpu mpc i r c ui t .

Ass ho wni nFi g. 5 ,t het e mp e r a t ur ed i f f e r e nc e b e t we e nt h es u c t i o na n dd i s c h a r geo fc o mpr e s s o r wa s1 3 5 ° Cwhe nt her e f r i ge r a ntp a s s e dt hr o ugh t he HESC att he ambi e ntt e mpe r at ur e of -6 ° C,andi nc as eofby-pas s( notpas s i ng t hr oughHESC)t het e mpe r at ur edi f f e r e nc e be t we e nt hes uc t i o ndi s c ha r geofc o mpr e s s o r was12 0° C atambi e ntt e mpe r at ur eof-6 ° C.

The r e f or e ,t hee f f e c toft heHESC ont he i nc r e a s eo fc o mpr e s s o rdi s c ha r get e mpe r a t ur e was1 5° C.

Att heambi e ntt e mpe r at ur eof-6° C,t he t e mpe r a t ur edi f f e r e nc ebe t we e nt hei nl e ta nd o ut l e to fc o nde ns e rwa s9 2 ° Ci nt her e f r i ge r a nt c i r c ui tpas s i ng t hr ough t he HESC.Unde r t hes amec ondi t i on,howe ve r ,t hatwas7 2° C i n t he r e f r i ge r antc i r c ui tpas s i ng t hr ough by-pas s .

The r e f or e ,t hee f f e c toft heHESC ont he t e mpe r at ur ei nc r e as eofwas20° C.

The s e r e s ul t s s howe d t hatt he COP of t heai rt owat e rhe atpumps ys t e m c oul dbe i nc r e as e dbyt heHESC.

4. 2.Wat ert emper at ur evar i at i onwi t h t hewat ermassf l ow r at e

Fi g. 6s howst het e mpe r at ur evar i at i onof

t hewat e rhe at e dbyc onde ns e roft hehe at

pumps ys t e m ac c or di ngt ot hewat e rmas s

f l ow r at e .

Ass hown i n Fi g. 6 ,i n c as eoft hei nl e t wat e rt e mpe r at ur eof15° C,t het e mpe r at ur e of t he wat e r he at e d by t he c onde ns e r de c r e as e dc ur ve dl ywi t ht hei nc r e as eoft he wat e rmas sf l ow r at e .

The wat e rt e mpe r at ur e de c r e as e d f r om 58 ° C t o 2 7° C whe n t hewat e rmas sf l ow r at ei nc r e as e df r om 100 ℓ/ hrt o400 ℓ/ hr . Cons e que nt l y,t he t e mpe r at ur e var i at i on oft hewat e rhe at e dbyt hec onde ns e rc oul d bec ont r ol l e dbyt hewat e rmas sf l ow r at e .

Fi gur e6 .Wat ert emper at ur ev ar i at i onwi t ht hewat ermas s f l ow r at e

4. 3.HESC ef f ecton t heCOP ofheat pumpsyst em

Fi gur e 7 .HESC ef f ec ton t he COP oft he heatpump s y s t em wi t ht heambi entt emper at ur ev ar i at i on.

Ass howni nFi g. 7 ,whe nt heHESC was i ns t al l e d be t we e n t he c onde ns e r and t he e vapor at or oft he he atpump c i r c ui t ,t he COPoft hes ys t e m was3 . 2att heambi e nt t e mpe r at ur eof-10 ° C,butt heCOP oft he s ys t e m not pas s i ng t he HESC was 2. 4 unde rt hes ameambi e ntc ondi t i ons .

Cons e que nt l y,t heCOP i nc r e as e dbyt he HESCwa s0 . 8 ,buta tt hea mbi e ntt e mp e r a t ur e above 4 ° C,t he COP of t he s ys t e m not pas s i ng t he HESC ( by-pas s c i r c ui t )was hi ghe rt han t hatoft he s ys t e m wi t h t he HESC.I no t he rwo r d s ,t heCOPo ft hes ys t e m wi t ht heHESC wa shi ghe rt ha nt ha to ft he s ys t e m no tp a s s i ngHESC( by-p a s sc i r c ui t ) ,a t t hea mbi e ntt e mp e r a t ur ebe l o w 4 ° C.The r e f or e , i ti sde s i r abl et oe mpl oy t heHESC i nt he c i r c ui toft he he atpump s ys t e m att he ambi e ntt e mpe r at ur ebe l ow 4° C.I nor de rt o ope r at e t he he at pump s ys t e m wi t h or wi t houtt he HESC,i twas c ompos e d of t wo-waypas s e soft heHESC andby-pas s ( Fi g. 1) .Cons e que nt l y,he atpump s ys t e m c oul dbeope r at e di nt wowaysac c or di ngt o t hea mbi e ntt e mpe r a t ur ea bo vea ndbe l o w 4 ° C.

5.Concl usi on

I n ge ne r a l ,t hee ne r gy s t o r a ges ys t e m i s i ne vi t a bl e f o r t he s o l a r e ne r gy ut i l i z a t i o n.

Fo r t una t e l ye no ugh,t hes o l a re ne r gyi ss t o r e d a bunda nt l yi nt hea i r ,t hee a r t ha ndt hewa t e r .

Unf or t unat e l y,howe ve r ,t het e mpe r at ur e var i at i onoft hes ol are ne r gys t or e di nt he ambi e ntai rac c or di ng t o t he r e gi ons and s e as onsi soneoft het r oubl e d f ac t or sf or t her e al i z at i onofs ol are ne r gys ys t e ms .

I n c as eoft hehe atpumps ys t e m us i ng

t hee ne r gys t or e di nt heambi e ntai rast he

he ats our c e ,t hepe r f or manc ewoul dr api dl y de c r e as e be l ow -1 0° C oft he ambi e ntai r t e mpe r at ur e .

I n t hi s s t udy,i n or de r t o s ol ve t he s e pr obl e ms ,t he HESC was de ve l ope d and adapt e d t o t he ai r -t o-wat e r he at pump s ys t e m a ndt heHESCe f f e c tont hi ss ys t e m wa sa na l yz e da nds umma r i z e dasf ol l ows . ( 1 )Co mpr e s s ordi s c ha r get e mpe r a t ur eo ft he

he atpump s ys t e m i ns t al l e d wi t h t he HESC was20° Chi ghe rt hant hatoft he s ys t e m wi t houtHESC ( by-pas s ) . ( 2 )Att hea mbi e ntt e mpe r a t ur eo f-1 0 ° C,t he

a i r -t o-wa t e rhe a tpumps ys t e m wi t ht he HESC c oul dbeope r a t e da tt heCOP o f t ha twa s 0 . 8 hi ghe r t ha n t ha toft he s ys t e m wi t houti t .

( 3 )Att heambi e ntt emper at ur ebel ow 4° C, t heCOPo ft hes ys t e m wi t ht heHESCwa s hi ghe rt ha nt ha to ft hes ys t e m wi t houti t , buta tt hea mbi e ntt e mpe r a t ur ea bove4 ° C t heCOPo ft hes ys t e m wi t ht heHESCwa s l o we rt ha nt ha to ft hes ys t e m wi t ho uti t . The r e f or e ,i ti sde s i r abl et oope r at et he s ys t e m wi t h t he HESC at t he ambi e nt t e mpe r at ur ebe l ow 4 ° C.

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