domestic refrigerators with absorption–diffusion units and heat-transfer panels

8/8/2019 Domestic refrigerators with absorptiondiffusion units and heat-transfer panels

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ELSEVIER PIE S0140-7007(96)00039-4

Int J. Refrig. Vo l. 19, No. 8, pp. 517- 521, 1996Copyright 1996 Elsevier Science Ltd and IIRPrinted in G reat Britain. All rights reserved0140-7007/96/$15.00

D o m e s t i c r e f r i g e r a t o r s w i t h a b s o r p t i o n - d i f f u s i o n u n i t sa n d h e a t - t r a n s f e r p a n e l s

G . F . S m i r n o v , M . A . B u k r a b a , T . F a t tu h a n d B . N a b u l s iO d e s s a I n s t it u t e o f L o w - T e m p e r a t u r e T e c h n i c s a n d E n e r g e ti c s , 1 /3 P e o t r V e l i k y S tr e e t,O d e s s a 2 7 0 1 0 0 , U k r a i n eR e c e i v e d 2 2 M a r c h 1 9 9 4 ; re v i s e d 2 2 F e b r u a r y 1 9 9 6

The possib il ity of essent ial increasing of ab sorp t ion -d i f fusion coo ler set refr igerat ing power by means ofseparat ing co ld t ransmission and d is t r ibu t ion processes in the inner refr igerator vo lumes f rom coldgenerat ion processes has been shown. The pro blem is so lved by using he at - t ransfer panels on the base ofheat tubes and vapor izat ion thermosiphons. The const ruct ion developed on the 'Kris tal l ' type domest iccooler basis has at tained a low tempe rature of -1 5C in the 155-1 volume at the ambient tem perature of20C and at the ambient tempe rature of 43C it was al lowed to reach - I C tempe rature wi thout usingaddi t ional heat insu lat ion . Copyrigh t 1996 Elsevier Science Ltd and I IR(Keywords: refrigerated cabinet; absorption -diffusionrefrigeratingunit; heat-transfer panel; hea t tube; evaporating thermalsiphon)

R e f r i g e r a t e u r s m e n a g e r s a g r o u p e s a b s o r b e u r s - d i f f u s e u r s e t ap a n n e a u x e c h a n g e u r s d e c h a l e u rLa poss ib i li tO es t m ont r~e d 'une augm entat ion considOrable du re ndem ent f r igor i f i que des rOf r ig~rateursabso rbeur s-d i f f useurs grhce ~ la s~parat ion des processus de gOnkrat ion e t d i s t r ibut ion du f r om dans l ' espacein t erne du r~f rig~rateur . Le prob l~me es t r~solu par u t i l isa t ion de pannea ux Ochangeurs de chaleur sur la base detubes thermiques e t de thermosyphons ~vaporateurs . Les modi f i ca t ions const ruct i ves correspondantes d 'unrOfrig~rateur m ~nager du t y pe 'Cri sta ll " ont perm is d 'obteni r une t em perature de - 15C dans un volume de 155 la v e c u n e t e m p e ra t u re d u m i l i e u a m b i a n t d e 2 0 C e t , a v e c u n e t e m p & a t u re d u m i l i e u a m b i a n t d e 4 3 C , u n etempOrature de -1 C sans calor i fugeage suppl~mentai re . Cop yrigh t 1996 Elsevier Science Ltd and I IR(Mo ts cl+s: arm oire frigorifique;groupe frigorifiqueabsorbeur diffuseur;panneau 6changeurde chaleur; ub e thermique"thermosyphon 6vaporateur)

T h e a b s o r p t i o n - d i f f u s i o n r e f r ig e r a ti n g u ni ts ( A D R U )h a v e a n u m b e r o f a d v a n t a g e s o v e r c o m p r e s s i o n o n e s:n o i se l e s s o p e r a t i o n , a b s e n c e o f m o v i n g p a r t s , e a s y a t t e n d -a n c e , p o s s i b i l i t y t o u s e v a r i o u s h e a t s o u r c e s , s u c h a se l e c t r i c c u r r e n t , k e r o s e n e , e t c .C o n s t r u c t i o n o f A D R U s c o m p r i se s r a m i fi e d s ys te m so f in t e r c o n n e c t e d l o o p s o f n a t u r a l c i r c u l a t io n . U n d e r t h ec o n d i t i o n s , w h e r e t h e d r i v i n g f o r c e o f c i r c u l a t i o n i s p r o -v i d e d b y d e n s i t y d i f f e re n t i a l , a c o m p l e x h y d r a u l i c s y s t e mw i t h p h a s e t r a n s i t i o n p r o c e s s e s i n e a c h e l e m e n t o fA D R U r e s tr i c ts t h e ra t e o f h e a t - a n d - m a s s e x c h a n g ep r o c e s s e s , w h i c h c a n a f f e c t a d v e r s e l y t h e l e v e l o f r e f r i g -e r a ti n g c a p a c it y o f A D R U s .S i m p li fi e d d i a g r a m o f a n A D R U is p r e s e n t e d i n F i g u r e1 . T h e u n i t is m a d e f r o m c a r b o n s te e l a n d c h a r g e d w i t hw a t e r - a m m o n i a m i x t ur e c o n t a i n in g 3 5 % a m m o n i a .P r e s e n t w i t h i n t h e u n i t i s i n e r t g a s h y d r o g e n a n d o p e r -a t i n g p r e s s u r e i n t h e u n i t i s 1 . 7 - 2 . 0 M P a .P r i n c ip l e o f o p e r a t i o n o f A D R U i s d e s c r i b e d b el o w .

N o m i n a l h e a t l o a d a m o u n t i n g t o 1 1 2 W is a p p l ie d t o t h eg e n e r a t o r 1 a n d w a t e r - a m m o n i a s o l u ti o n b o il s. A m m o -n i a v a p o u r a s c e n d s b y v a p o u r l i n e 2 t o t h e c o n d e n s e r 3

w h e r e i t is c o n d e n s e d a n d l iq u i d a m m o n i a e n t e rs t h ee v a p o r a t o r 5 b y th e l in e 4. I n t h e e v a p o r a t o r , a m m o n i a ise v a p o r a t e d a n d d i ff us e s i n to h y d r o g e n - a m m o n i a m i x o fl o w a m m o n i a c o n t e n t . O w i n g t o t h e s e p r o c e s s e s r e f r i g -e r a t i n g e f fe c t i n A D R U i s a c h i e ve d .C o o l ed v a p o u r - g a s h y d r o g e n - a m m o n i a m i x o f h ig ha m m o n i a c o n t e n t e n t e r s t he r e c e i v e r 6 a n d t h e n a s c e n d sb y c o i le d a b s o r b e r 7 t o t h e e v a p o r a t o r 5 . F l o w o f v a p o u r -g a s h y d r o g e n - a m m o n i a m i x i s i n d u c e d b y b u y o a n c yf o r c e d u e t o d e n s i t y d i f f e r e n c e i n c o n n e c t i o n w i t h v a r i e dc o n c e n t r a t i o n o f a m m o n i a . B r o u g h t t o th e t o p p a r to f th e a b s o r b e r f r o m t h e g e n e r a t o r 1 b y t h e l in e 8 d u et o a c t i o n o f t h e r m o c o m p r e s s o r o p e r a t i n g a c c o r d i n g t ov a p o u r li f t p a t t e r n is a w e a k w a t e r - a m m o n i a s o l ut io nw h i c h f lo w s d o w n t h r o u g h c o i l e d a b s o r b e r 7 a n d a b s o r b sa m m o n i a f r o m th e v a p o u r - g a s h y d r o g e n - a m m o n i a m i xw h i c h a s c e n d s o p p o s i t e t o s o l u t i o n f l o w . A s a r e s u l t ,w a t e r - a m m o n i a s o l ut io n o f h i gh a m m o n i a c o n c e n t r a -t i o n is f o r m e d a n d b r o u g h t t o t h e g e n e r a t o r 1.O u t e r t u b u l a r s u r f a c e s o f t h e e v a p o r a t o r 5 a n da b s o r b e r 7 i n c l u d e d i n t h e i n v e s t i g a t e d u n i t h a v e n of in s . O v e r a l l l e n g t h o f t h e a b s o r b e r i s 6 . 5 m , o u t s i d e

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5 1 8 G.F. Smi rnov et a l .

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Inne r su r face o f r e f r ige ra t ion cab ine t (m 2)H e a t - t r a n s f e r c o e ff ic i en t ( W m - 2 K - 1H e a t - t r a n s f e r p a n e l a r e a ( m 2 )E n v i r o n m e n t a l t e m p e r a t u r e ( C )Tempera tu re i n p l anes A, B , C ( C)

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ha,b,c,d,eT

A v e r a g e t e m p e r a t u r e i n s i d e t h ere f r ige ra t ion cab ine t ( C)Al t i t ude o f t he r e f r ige ra tion ca b ine t (m)G e o m e t r y d i m e n s i o n ( m )T i m e o f w o r k (h )

d i a m e t e r o f t h e t u b e is 1 8 m m . A s e v i d e n c e d b yexpe r imen ta l i nves t iga t ions , such absorbe r ensure s r e l i -a b l e o p e r a ti o n o f A D R U a t a m b i e n t t em p e r a tu r e s u p t o45C. Ev ap ora to r t ube i s e ll i p ti c in c ross - sec t ion . O ve ra l ll eng th o f t he e vap ora to r i s 1 .7 m and i t s a rea i s 0 .14 m 2 .I t i s know n tha t f ins a re r equ i red fo r e f fec tive pe r -f o r m a n c e o f a n o r d in a r y - d e s i g n e d e v a p o r a t o r . H o w e v e r ,f i nn ing g ives r i se t o t empera tu re va r i a t i ons ove r t hei n si d e s p a ce o f A D R U a n d u s a b l e s p ac e is b l o c k e d u p .Ap pl i ca t ion o f hea t - t r ansfe r p ane l a l lows be t t e r so lu t iono f t h is p r o b l e m p r o v i d e d t h a t r e li a b le t h e r m a l c o n t a c tb e t w e e n s u r f a c es o f p a n e l a n d e v a p o r a t o r is a c h ie v e d .The condense r 3 i s de s igned wi th f i ns o f ove ra l l hea texchang ing a rea o f 0 .30 m 2 .S i nc e th e l o w r e f r ig e r a ti n g p o w e r o f d o m e s t ic A D R U sr a is e s t h e p r o b l e m o f ju d i c i o u s u s e o f e n e r g y r e s o u r c e s ine a c h e le m e n t o f th e u n i t, t h e A D R U c o n s t r u c t i o n isp rov ided wi th ga s and l i qu id hea t exchange rs , f i nnedcons t ruc t ions o f cond ense r and a bso rbe r , which s ign if i-can t ly compl i ca t e s t he un i t s manufac tu r ing p rocess .T a k i n g i n t o c o n s i d e r a t i o n t h e a f o r e s a i d f e a t u r e s o fADRUs i t seems necessa ry to i nves t iga t e t he poss ib i l i t yo f r a is i n g t h e r a te o f p r o ce s s e s i n A D R U s a n d i n c re a s in gthe i r r e f r ige ra t ing capac i ty ma te r i a l l y by sepa ra t ing theprocesse s o f the t r ansfe r o f r e f r ige ra t ion and d i s t r i bu t ionin r e f r ige ra to r ' s i n t e rna l spaces f rom re f r ige ra t ion gen-e ra t ing p rocesse s . An e f fec tive app roac h to so lu t ion o f

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8 ~ ~ 4 o o ~ 1 20F i g u r e 1 S i m p l i f i e d d i a g r a m o f A D R U : 1 - g e n e r a t o r ; 2 - v a p o u r -c a r r y i n g l i n e ; 3 - c o n d e n s e r ; 4 - l i q u i d a m m o n i a l i n e; 5 - e v a p o r a t o r ;6 - r e c e i v e r t a n k ; 7 - a b s o r b e r ; 8 - w e a k s o l u t i o n l i n e ; 9 - r e f r i g e r a t i o nc a b i n e t ; l 0 - p o i n t s o f i n s t a l l a t i o n o f t e m p e r a t u r e t r a n s d u c e r s , ( 1 ) - ( 6 )- n o s o f t e m p e r a t u r e t r a n s d u c e r sF i g u r e 1 S c h e m a s i m p l i f i d d e G F A D : 1 - g ~ n d r a t e u r ; 2 - c o n d u i t e d ev a p e u r ; 3 - c o n d e n s e u r ; 4 - c o n d u i t e d ' a m m o n i a q u e l i q u i d e ; 5 -d v a p o r a t e u r ; 6 - c u v e d u c o l l e c t e u r ; 7 - a b s o r b e u r ; 8 - c o n d u i t e d es o l u t i o n f a i b l e ; 9 - a r m o i r e f r i g o r i f i q u e ; 1 0 - e n d r o i t s d ' i n s t a l l a t i o n d e st r a n s f o r m a t e u r s t h e r m i q u e s ; ( 1 ) . . . . . ( 6 ) - n u m ~ r o s d e s t r a n s f o r m a t e u r st h e r m i q u e s

t h i s p rob lem i s conce rn ed wi th app l i ca t ion o f hea t -t r a n s f e r p a n e l s b a s e d o n h e a t t u b e s o r e v a p o r a t i n gt h e r m a l s i p h o n s, w h i c h i n v o l v e d th e p r o b l e m o f h e a t-eng inee r ing des ign ing o f r e f r ige ra t ion c ab ine t s wi th hea t -t r a n s f e r p a n e l s a n d A D R U s .Survey of the subjectT h e a p p l i c a ti o n o f h e a t- t r a n s fe r p a n e l s b a s e d o n h e a ttubes and the rm a l s iphons , wh ich a ll ow jud ic iousred i s t r i bu t ion o f hea t f luxes , needs subs t an t i a t i on .Thus , i n re f . 1 t he r e f rige ra t ing ch amb er eva pora to r i sthe rma l ly con nec ted w i th a me ta l shee t made in t he fo rmof r ad i a to r . In t he l a t e r de s ign o f i c e gene ra to r 2 use i sma de o f a hea t t ube , which runs f rom the f r eez ingchamber t o t he coo led f r e sh p roduc t s chamber . In r e f . 3c o n n e c t e d t h e r m a l l y t o A D R U b r a n c h e s a r e h e a t -t r ansfe r dev ice s , whe re phase t r ans i t i on p rocesse s t akep lace , whi l e t he hea t - t r ansfe r dev ice s themse lves fo rm thewa l l s o f t he r e f r ige ra t ion cab ine t .A se t o f expe r imen ta l i nves t iga t ions i n to app l i ca t iono f h e a t- t r a n s fe r p a n e ls c o n n e c t e d w i t h e v a p o r a t o r s o fADRUs has been ca r r i ed ou t i n t he Sc i en t i f i c andP r o d u c t i o n A s s o c i a t i o n o f A p p l i e d M e c h a n i c s 4. T h ere su l t s o f t hose i nves t iga t ions have been adop ted inproduc t ion and domes t i c r e f r ige ra to r s t ype 'Kr i s t a l l 'w i t h A D R U a n d h e a t - t r a n s f e r p a n e l s b r o u g h t t o a f u l l -sca l e p roduc t ion l eve l a t one o f t he r e f r ige ra to r -p roduc ing fac to r i e s .A l o n g w i t h t h e p r o b l e m o f j u d i c i o u s u s e o f r ef r ig e r a -t i on , t he re ex i s ts a p rob le m of s imul t aneo us ly i nc rea s ingthe usab le space and re f r ige ra t ing e f fec t . Unde r cond i -t i ons o f la rge - scal e p rodu c t ion o f r e f r ige ra t ion cab ine t so f a ce r ta in s t an da rd s ize wi th i nc rea sed in t e rna l usab les p a c e, t h e s e p r o b l e m s c a n b e i m p r o v e d b y u s in g t w o o rt h r ee A D R U s i n s t e a d o f o n e . D e p e n d i n g o n t h e s ta n d a r ds iz es o f r ef r ig e r a ti o n c a b i n e t s a n d A D R U s t h is a p p r o a c hcan be implemented by d i f f e ren t de s ign ing me thods . Agood des ign fo r r e f r ige ra t ion cab ine t s o f sma l l s t anda rds i z e i s p r o v i d e d b y m o u n t i n g t h e a d d e d A D R U b e h i n dthe ma in un i t i n pa ra ll e l t o t he l a t te r . T he dep th o f t hecab ine t , i n t h i s c a se , wi l l be i nc rea sed by 0 .10m maxi -m u m . C o n f i g u r a t i o n o f b o t h A D R U s m u s t a ll o w ef fe c-t i ve implem enta t ion o f t he rma l i nsu l a t i on , a s show n fo re x a m p l e i n Figure 2a.The u se o f hea t - tr ansfe r pane l s ma kes i t poss ib l e t on e w l y s ol v e t h e p r o b l e m o f A D R U ' s a p p l i c a ti o n i n th econs t ru c t ion o f ches t - t ype re fr ige ra t ion cab ine t s . I f t here f r ige ra tion cab ine t i s o f t he ches t t ype , i t is exped ien t t oa r range the un i t s i n t he p l ane pa ra l le l t o t he r ea r w a l l o fthe ches t , a s shown in Figure 2b.Such a r rangement o f t he un i ts p ro mo te s be t t e r d i st r ibu-t i on o f evapora to r su r faces ove r t he r e f r ige ra tion cab ine tspace and fac i li ta tes designing of a comm on h eat - t ransferpane l. In such a ca se the pane l ma y be des igned bo th w i th


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Absorpt ion-dif fusion units and heat- transfer panels 51 9(a) (b) (c)

Figure 2 D i f f e r e n t d e s ig n v e r s i o n s o f re f r i g e r a te d c a b i n e t s w i t ha b s o r p t i o n - d i f f u s i o n r e f r i g e r a t in g u n it s : a - e c h e l o n a r r a n g e m e n t o fA D R U ; b o n e - p l an e h o r i z o n ta l a r r a n g e m e n t o f A D R U ; c o n e -p l a n e ve r ti c al a r r a n g e m e n t o f A D R U ; 1 - A D R U ; 2 - r e f ri g e ra t e dc a b i n e tF i g u r e 2 V a r i a n t e s d e r ~ a l i sa t i on d ' a r m o i r e s fr i g o r i f i q u e s a v e c G F A D :a - a r r a n g e m e n t d e G F A D e n dc h e lo n s ; b - a r r a n g e m e n t h o r i z o n t a l d eG F A D d a n s l e p l a n ; e - a r r a n g e m e n t v e r t ic a l d a n s l e p l a n d e G F A D ; 1 -G F A D ; 2 a r m o i r e f r i g o r ! fi q u e

r e f r i g e r a n t - c a r r y i n g p i p i n g f o r i n d i v i d u a l A D R U a n d w i t ha c o m m o n r e f r ig e r a n t- c a r r yi n g p i p in g d e p e n d i n g o ns p e c if i c p r o b l e m s o f r e f r i g e r a t o r e n g i n e e r in g .T h e t h e r m a l i n s u l a t io n o f t h e e v a p o r a t o r s , i n t h is c a s e ,m u s t b e a r r a n g e d s o t h a t t h e h e a t - t r a n s f e r p a n e l s s h o u l dn o t i n t e rf e r e w i t h t h e p r o c e s s o f p l a c i n g p r o d u c t s i n t ot h e c h e s t a n d t a k i n g t h e m o u t . I n a v e r t i c a l v e r s i o n o fr e f r i g e r a t io n c a b i n e t t h e A D R U m a y b e a r r a n g e d v e r t i-c a l l y i n th e s a m e p l a n e o n e a b o v e t h e o t h e r ( s ee Figure 2c).U s e o f d o u b l e d o r t r i p le d u n i t s i n o n e r e f r i g e r a t i o nc a b i n e t a s p e r t h e l a y o u t s h o w n i n Figure lc ( w i t h o u th e a t - t r a n s f e r p a n e l s ) i s i n e f fe c t i v e b e c a u s e i t l e a d s t oi r r e g u la r i t y o f t h e t e m p e r a t u r e f ie l d a n d r e d u c e s th eu s a b l e s p a c e o f th e r e f r i g e r a t i o n c h a m b e r . T o d e c r e a s es u c h i r r e g u l a r i t y i t i s a d v i s a b l e t o u s e h e a t - t r a n s f e rp a n e l s i n th e f o r m o f h e a t tu b e s o r t w o - p h a s e t h e r m a ls i p h o n s b u i lt i n t o m e t a l p a n e l s . T h e o p e r a t i n g c o n d i t i o n so f d o m e s t i c r e f r i g e r a t i o n c a b i n e ts p r e d e t e r m i n e t h e l o c a -t i o n o f t h es e h e a t - t r a n s f e r p a n e l s a l o n g t h e s id e a n d r e a rw a l l s o f t h e c a b i n e t s . I t i s e a s y t o s e e t h a t t h e t o t a l a r e a o ft h e e v a p o r a t o r c a n b e s u b s t a n t ia l l y ( b y o n e a n d a h a l f o rt w o f o l d ) i n c r e a s e d a s c o m p a r e d w i t h t h a t o f t h e k n o w ne v a p o r a t o r d e s i gn . T h e r e f o r e , in s p i te o f t h e a d d e d h e a t -t r a n s f e r p a n e l, w h i c h c r e a t e s a n a d d i t i o n a l t h e r m a l r e s is t -a n c e , t h e t o t a l h e a t f l u x r e m o v e d w i l l b e i n c r e a s e d .I t i s a c r u c i a l p r o b l e m t o r e d u c e t h e c o n t a c t ' s t h e r m a lr e s is t a nc e . T h e m a x i m u m a r e a o f c o n t a c t b e t w e e n t h eA D R U ' s e v a p o r a t o r a n d t h e h e a t - tr a n s f e r p a n e l ca n b eo b t a i n e d b y u s in g t h e e v a p o r a t o r m a d e i n t h e fo r m o f af l a t c o i l o r i e n t e d i n t h e v e r t i c a l p l a n e .T h i s p a p e r p r e s e n t s t h e e x p e r i m e n t a l r e s u l t s w h i c hc o r r o b o r a t e t h e p o s s i b i li t y i n p r i n c i p l e t o m a k e a f r e e z e r -r e f r i g e r a t o r w i t h tw o A D R U s w h e r e t h e e v a p o r a t o r s w i llp r o v i d e s e r v ic e f o r th e c o m m o n h e a t - t r a n s f e r p a n e l w i t hb u i l t - i n h e a t t u b e s .De s c r i p t i o n o f t e s t b e n c h a n d i n ve s t i g a t i o n p r o c e d u r eU s e d a s a s u b j e c t o f i n v e s t i g a t i o n w a s a r e f r i g e r a t i o nc a b i n e t t y p e ' K r i s t a l l - 4 0 1 - 1 ' o f 1 55 1 c a p a c i t y w i t h o n e o rt w o A D R U s w h o s e e v a p o r a t o r s w e r e t e st e d in t h e r m a lc o n t a c t w i t h h e a t - t r a n s f e r p a n e l s o f d i f fe r e n t d e s i g n s . I nt h e fi r st s e t o f e x p e r i m e n t s t h e e v a p o r a t o r o f A D R U w a st h e r m a l l y c o n n e c t e d w i t h a U - s h a p e h e a t t u b e c o n n e c t e dt o t h e p a n e l w h i c h f o r m e d a f r e e z i n g c h a m b e r .

T h e t e m p e r a t u r e i n s i d e t h e r e f r i g e r a t i o n c a b i n e t a n dt h e e n v i r o n m e n t a l t e m p e r a t u r e w e r e c o n s t a n t l y m o n i -t o r e d . T h e t e m p e r a t u r e t r a n s d u c e r s i n t h e r e f r i g e r a t i o nc a b i n e t w e r e m o u n t e d i n t h r e e e q u a l l y s p a c e d p l a n e sp a r a l l e l t o t h e b o t t o m . T h e t e m p e r a t u r e m e a s u r e m e n te r r o r w a s n o t m o r e t h a n + / - 0 . 5 C . A l l m e a s u r e m e n t sw e r e t a k e n i n s t e a d y - s t a te c o n d i t i o n s. U s e d a s a m e a s u r -i n g i n s t ru m e n t w a s a n e l e c t r o n ic m e a s u r i n g s y s t em w h i c ha l l o w e d f o r t a k i n g m e a s u r e m e n t s f r o m 2 2 t e m p e r a t u r et r a n s d u c e r s w i t h i n 3 0 s . A s a r e s u l t o f th e m e a s u r e m e n t s( a t t h e a m b i e n t a i r t e m p e r a t u r e o f 2 0 C ) i t w a s f o u n dt h a t t h e a v e r a g e t e m p e r a t u r e i n th e f r e e z i ng c h a m b e rw a s - 1 8 C . N o a p p r e c i a b l e d if f e r en c e o f t e m p e r a t u r e sw a s o b s e r v e d i n t h e r e f r i g e r a t io n c h a m b e r b e t w e e n t h ec e n t r a l a n d l o w e r p l a n e s . T h e s e t e m p e r a t u r e s w e r ew i t h i n m i n u s 1 t o m i n u s 2 C .T h e e v a p o r a t o r c o n s t r u c t i o n o f t h r e e - d i m e n s i o n a lv e r s i o n w i t h s e p a r a t e l y l o c a t e d f r e e z i n g a n d r e f r i g e r a t i n gs e c t i o n s , a s w e l l a s t h e s m a l l c a p a c i t y o f t h e f r e e z i n gc h a m b e r t a n g i b ly i m p a i r t h e c o n s u m e r q u a l it i es o f t h a tc o n s t r u c t i o n . T h e a f o r e s a i d d i s a d v a n t a g e s c a n b ea v o i d e d b y u s in g s t o c k -p r o d u c e d A D R U s w i t h e v a p o ra -t o r s o f f la t c o n s t r u c t io n , a t t a c h e d t o w h i c h a r e h e a t t u b e sw i t h d e v e l o p e d f i n s. U s e o f v a r i o u s f o r m s o f f in o n t h eh e a t t u b e s m a k e s i t p o s s i b l e t o d e s i g n a r e f r i g e r a t i o nc a b i n e t w i t h i n c r e a s e d f r e e z in g c h a m b e r o r t o c r e a t e as in g le v o l u m e o f f r e ez i n g c a b i n e t w i t h u n i f o r m t e m p e r a -t u r e f i e l d . H o w e v e r , a s c a n b e s e e n f r o m t h e c a l c u l a t i o n sa n d e x p e r i m e n t a l d a ta , a t t h e a m b i e n t a i r t e m p e r a t u r e o f2 0 C t h e a v e r a g e t e m p e r a t u r e i n t h e r e f r i g e r a t i o n c a b in e to f t h a t c o n s t r u c t i o n w i l l n o t d r o p b e l o w m i n u s 5 C , i .e .t h e r e f r i g e r a t i o n c a b i n e t c a n n o t f u n c t i o n a s a f r e e z e r .U n d e r t h e c o n d i t i o n s o f e f fi c i en t f u l l- s c a l e p r o d u c t i o no f re f r i g e r a t io n c a b in e t s a n d A D R U s o f c e r t a i n s t a n d a r ds iz e s t h e p r o b l e m o f i n c r e a s i n g t h e u s a b l e s p a c e o f ar e f r i g e r a t i o n c a b i n e t a n d a t t h e s a m e t i m e d e c r e a s i n g t h et e m p e r a t u r e l e v e l s i n th e w o r k i n g c h a m b e r s o f t h e r e f ri g -e r a t i o n c a b i n e t , c a n b e s e t t l e d b y i n c r e a s i n g t h e n u m b e ro f un i ts o p e r a t i n g f o r o n e c o m m o n v o l u m e . S u c h a ne n g i n e e r i n g s o l u t i o n u n d e r t e m p e r a t e c l i m a t i c c o n d i -t i o n s a l lo w s f o r o b t a i n i n g a f r e e z i n g c h a m b e r i n s t e a d o fr e f r i g e r a t o r , o r a c o r r e s p o n d i n g r e f r i g e r a t o r w i t h a nA D R U , i f i t ta k e s p l a c e u n d e r t r o p i c a l c o n d it i o n s .In s t a l l a t i o n o f two u n i t s , p a r t i cu l a r ly fo r t h e r e f r i g e ra t i o ncab in e t t y p e 'K r i s t a l l ' o f 1 5 5 -1 cap ac i ty , can b e a f f ec t edwi th o u t a l t e r a t i o n s , i f o n e o f t h e u n i t s h as a f l a t - t y p ee v a p o r a t o r w h i l e in t h e o t h e r u n i t i t is o f t h r e e - d i m e n s i o n a la n d f l a t c o n s tr u c t i o n s . T h e e x p e r i e n c e o f d e s ig n i n g t h is t y p eo f f r eeze r - r e f r i g e ra to r s ex i s t s i n o u r In s t i t u t e .A n o t h e r s e t o f e x p e r i m e n t s w a s c a r r i e d o u t t o d e t e r m i n et h e e f f e c ti v e n e s s o f t h e r e f r i g e r a t i o n c a b i n e t w i t h t w oA D R U s w h o s e e v a p o r a t o r s a r e c o n n e c t e d t o h e at - tr a n s fe rp a n el s. P e r f o r m a n c e o f in d i vi d ua l u n it s o f A D R U w a sc h e c k e d a g a i n s t r e s u lt s o f t e m p e r a t u r e m e a s u r e m e n t sm a d e o n f la t e v a p o r a t o r u n i t. A r r a n g e m e n t o f t e m p e r a -t u r e t r a n s d u c e r s i s s h o w n i n Figure 1. T e m p e r a t u r et r a n s d u c e r ( a ) w a s i n s t a l le d a t t h e o u t l e t o f t h e c o n d e n s e rw h i l e ( b ) , ( c ) a n d ( d ) w e r e m o u n t e d t o t h e e v a p o r a t o r i n0 . 4 5 m i n t e r v a l s s t a r t i n g f r o m t h e i n l e t h o l e a n d ( e ) a n d ( f )w e r e p la c e d t o t h e t o p a n d b o t t o m o f t h e a b s o r b e r ,r e s p e ct i ve l y . R e s u lt s o f t e m p e r a t u r e m e a s u r e m e n t s a r es u m m a r i z e d i n Table 1. E x p e r i m e n t s s h o w t h a t A D R Ui n t e g r a t e d w i t h h e a t - t r a n s f e r p a n e l o p e r a t e s s a t i s f a c t o r i l yo v e r t h e w h o l e e x a m i n e d r a n g e o f a m b i e n t t e m p e r a t u r e s .I t is k n o w n t h a t th e t e m p e r a t u r e o f A D R U e v a p o r a t o r


4/5

5 2 0 G . F . S m i r n o v et a l .

surface contrary to the temperature of evaporators ofvapour-compression refrigerating machines varies continu-ously from the minimum value to the maximum one whenno refrigerating effect is observed. Therefore, calculation ofCOP value for ADRU is arbitrary by its nature.On the other hand, no techniques for calculation ofCOP for ADRU are currently available and experi-mental data obtained for determination of this para-meter are rather particular. If guided by determinationof refrigerating capacity of ADRU from outside heatfluxes using experimental values of k F obtained by thetechnique in ref. 5, COP value for investigated ADRUsat temperatures in the refrigeration cabinet between 0and -15C will be 0.35.Used as a specimen was the refrigeration cabinet ofrefrigerator 'Kristall-404-1' of 155-1 capacity with themain ADRU having a three-dimensional and flat typeevaporator which was in contact with the freezingchamber where a U-shape heat tube was mounted. Thefreezing chamber was formed by the plates of the heattube finning. Mounted behind the main unit was theadditional unit with evaporator of fiat construction. Asystem of L-shape and U-shape heat tubes with devel-oped fins was attached to the evaporator located insidethe refrigeration cabinet in parallel to its rear wall. Thelayou t of the temperature transducers in the refrigerationcabinet under test are illustrated in Figure 3.Heat-tr ansfer panels of used versions constructed onthe basis of heat tubes are shown in Figure 4 . The heat-transfer panels are made from aluminium and ammo-nia is used as a refrigerating medium. Other designs ofheat-transfer panels more judicious than investigatedin this paper may also be used. Areas of heat-transfersurfaces of panels shown in Figure 4 are, respectively,S a = 0.64m"2, S b = 0.13m 2, S c = 0.45m 2.

The refrigera tion cabinet was enclosed in a contro lledconfined space where the ambient temperature waspreset and maintained within the range of 20 to 45C

T a b l e 1 R e s u l t s o f t e m p e r a t u r e m e a s u r e m e n t s o v e r th e s p a c e o fA D R UT a b l e a u 1 R d s u l t a t s d e s m e s u r e s d e t e m p e r a t u r e s d a n s l e c i r c u i t d eG F A DT e m p e r a t u r e A m b i e n t t e m p e r a t u r e ,~ ' Ct r a n s d u c e r 2 0 3 2 4 3! 3 2 3 6 4 62 - 2 7 - 2 4 - 2 23 - 1 7 - 1 2 - 84 - 8 - 3 15 3 8 4 3 4 86 4 1 4 9 5 9

with variations not exceeding +/-IC. In the courseof the experiments the temperature field in the refrigera-tion cabinet and thermostatted space was continuouslymonitored. The time to reach steady-state conditionswas from 5 to 7 h. The temperature variations withineach plane did not exceed +/-0.5C. The temperaturedistribution with the height of the refrigeration cabinet inthree configurations A, B and C is illustrated in Figure 5.Within the entire range of the environmental tempera-ture the variations of the temperature with the height ofthe refrigeration cabinet did not exceed +/-0.8C,therefore to characterize the temperature field insidethe refrigeration cabinet it is possible to use thearithmetic mean value of the readings received from allthe temperature transducers mounted inside the cabinet.The relationship of the average temperature inside therefrigeration cabinet to the environmental temperature isshown in Figure 6. It can be seen that with the rise of theenvironmental temperature from 20 to 32C the averagetemperature in the refrigeration cabinet is increased from-1 5 to -10C, i.e. within that range of the environ-mental temperatures the construction under investi-gation proves to be a good refrigerator and provides acertain potential for designing a freezer on that basis.

~ A-___A7 !

i~ d vle

F i g u r e 3 S c h e m e o f a r r a n g e m e n t o f h e a t - t r a n s f e r p a n e ls , e v a p o r a t o r s a n d p o i n t s o f i n s t a l l a ti o n o f t e m p e r a t u r e t r a n s d u c e r s : 1 - m a i n A D R Ue v a p o r a t o r ; 2 - a d d i t i o n a l A D R U e v a p o r a t o r ; 3 - h e a t tu b e s ; 4 - f i n t y p e f i b b i n g h e a t - t r a n s f e r p an e l s ; 5 - t e m p e r a t u r e t r a n s d u c e r s ; 6 - A D R U ; 7 -r e f r i g e r a t e d c a b i n e t c a s in g ; 8 - r e f r i g e r a t e d c a b i n e t d o o r ; A , B , C z o n e s o f i n s t a l l at i o n o f t e m p e r a t u r e t r a n s d u c e r s ; h = 1 .0 m ; a = 0 . 2 8 m ; b = 0 . 3 5 m ;c = 0 . 3 5 m ; d = 0 . 3 8 m ; e = 0 . 0 3 m ; f = 0 . 4 1 mF i g u r e 3 S c h O n a d ' a r r a n g e m e n t d ' d v a p o r a t e u r s a v e c p a n n e a u x d e t r a n s m i s s i o n d e c h a l e u r e t e n d r o i ts d ' i n s t a ll a t i o n d e s t h e rm o c o u p le s ." I - ~ v a p o r a t e u rp r i n c i p a l d e G F A D ; 2 - d v a p o r a t e u r a d d i t i o n n e l d e G F A D ; 3 - c a l o d u c s ; 4 p a n n e a u x d e t r a n s m i s s io n d e c h a l e u r ~ n e r v u r e s - n a g e o ir e s ; 5 - t h e r m o c o u p l e ;6 - G F A D ; 7 c o r p s d e l' a r re o i re f r i g o r i f i q u e ; 8 - p o r t e d e l ' a rm o i r e f r i g o r i f i q u e ; A , B , C d e s z o n e s d ' i n s t a l l a ti o n d e s t h e r m o c o u p l e s : h = 1 , 0 re ,"a = 0 , 28 r e, " b = 0 , 35 r e ; c = 0 , 35 re ," d = 0 , 38 m ; e = O , 0 3 r e , ' f = 0 , 4 1 r e


5/5

A b s o r p t i o n - d i f f u s i o n u n i ts a n d h e a t -t ra n s f e r p a n e l s 521

( a ) ( b )

~ - - - - - - 2 1 0 - .

(c )

r - _ _ - _ _

i ~ 3 8 0 - ~

F i g u r e 4 I n v e s t i g a t e d v e r s i o n s o f h e a t - t r a n s f e r p a n e l s b a s e d o n h e a t tu b e s : a - h e a t - t r a n s f e r p a n e l w i t h U - s h a p e d h e a t t u b e ; b - h e a t - t r a n s f e r t u b ew i t h t h r e e L - s h a p e d h e a t t u b e s ; c - h e a t - t r a n s f e r p a n e l w i t h t w o L - s h a p e d h e a t t u b e s ; 1 - h e a t t u b e ; 2 - f i n n i n gF i g u r e 4 Variantes ~tudi~es de pan nea ux de transmission de chaleur sur la base de tubes thermiques: a - panneau de transmission de chaleur avec tubethermique en II; b - panneau de transmission de chaleur avec trois tubes thermiques en F; c panneau de transmission de chaleur avec deu x tubesthermiques en F; 1 - tube thermique; 2 - nervures-nageoires

Uo

.1=

- 5

- 1 0

- 1 5

+ +

-o- BI to c = 4 3 C + C

- 8 + \I

)oc = 32C

t = 2 0 C I/ o co + o , o + \ % _I I I8 10 12

T ( H )F i g u r e 5 T e m p e r a t u r e d i s t r i b u t i o n o v e r t h e h e i g h t o f r e fr i g e r a t edc a b i n e t a t d i f f e re n t a m b i e n t t e m p e r a t u r e s a s a f u n c t i o n o f w o r k t i m e : l- g e n e r a l i z i n g l i n e s ; A , B , C - s e e Figure 3F i g u r e 5 R@artition de la temperature sur la hauteur de l'armoirefrigorifiqu e en fonct ion de la durde de fonct ionne ment pour diversestemperatures ambiante s: 1 - courbes de gdn#ralisation ; A, B, C - voir lal#gende de la Figure 3

W h e n t r o p i c a l c o n d i t i o n s w e r e s i m u l a t e d i n t h e t e m -p e r a t u r e c o n t r o l l e d s p a c e , t h e a ve r a g e t e m p e r a t u r e i nt h e r e f r i g e r a t i o n c a b i n e t wa s 0 C , i . e . t h e c o n s t r u c t i o nu n d e r i n v e s t i g a ti o n d e m o n s t r a t e d s t a b le p e r f o r m a n c e i nt h e c a p a c i t y o f a r e f r i g e r a t o r u n d e r t r o p i c a l c l i m a t i cc o n d i t i o n s .C o n c l u s i o n sB y u s i n g h e a t - t r a n s f e r p a n e l s t h e p r o c e s s o f t r a n s f e r a n dd i s t r i b u t i o n o f r e f r i g e r a t i o n i n t h e i n t e r n a l s p a c e s o f t h er e fr i g er a t io n c a b i n e t w i th A D R U c a n b e s ep a r a t e d f r o mr e f r i g e r a t i o n g e n e r a t i n g p r o c e s s . T h i s a l l o ws b e t t e r c o o l -i n g wi t h i n t h e r e f r i g e r a t i o n c a b i n e t s p a c e .

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F i g u r e 6 D e p e n d e n c e o f t h e a v e r a g e t e m p e r a t u r e i n r e f r i g e ra t e dc a b i n e t f r o m a m b i e n t t e m p e r a t u r e : l - g e n e r a l i z a t i o n o f t h e e x p e r i-m e n t a l d a t aF i g u r e 6 Relation entre la temp#ratur e moye nne c lans l'armoirefrigo rifique et la temp#rature a mbian te; 1 - g#n~ralisation des donn~esexpdrimentaless u b s t a n t i a te t h e f ie ld o f e ff ec ti ve a p p l i c a ti o n o f A D R U sin des igning freez ing chambers and in creat ing domest icrefr igerators wi th those uni t s intended for service undertropical c l imat ic condi t ions , as wel l as domest ic refr ig-e r a to r s w i t h A D R U s w i t h u s ab l e v o l u m e o f 3 0 0 t o 4 0 01 .

Re f e r e n c e s1 S w e d i s h P a t e n t n o 1 7 72 0 3 , 1 2 5 B 1 5 / 1 0 , a p p l . n o . 1 06 5 0 / 5 3 o fN o v . 2 8 ( 1 9 5 3 )2 U . S . P a t e n t n o . 4 0 0 3 2 1 4 , 1 2 5 C 1 / 0 8, a p p l . n o . 6 4 5 6 2 7 o f D e c . 3 1

(1975)3 E u r . P a t e n t n o . 0 3 2 6 8 8 1 , 1 25 B 1 5 / 1 0 , 2 5 / 0 0 , B I n o . 32 ( 1 9 8 9 )4 S m i r n o v - V a s i l i e v , K . G . , C h e r n y s h o v , V . F . , D v i r n y , V . V . et al.A p p l i c a t i o n o f h e a t t u b e s a n d t h e r m a l s i p h o n s in d o m e s t i cr e f r i g e ra t o r s , t h e s i s o f p a p e r f o r S c . a n d E n g . C o n f . R e f r i g e r a -t i o n fo r N a t i o n a l E c o n o m y , L e n i n g r a d (1 9 9 1)5 C h o o k l i n , S . G . , C h u m a k , L G . L a b o r a t o r y m a n u a l f o r t h e

c o u r s e Refrigerating Machines F o o d I n d u s t r y P u b l is h e r s,M o s c o w ( 1 9 74 ) , 2 87

domestic refrigerators with absorption–diffusion units and heat-transfer panels

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