Journal of Scientific & Industri al Research Vol. 60, July 200 I , pp 591-600

Domestic Refrigerators: Field Studies and Energy Efficiency Improvement

M Siddhartha Bhatt

Central Power Research Institute, Energy Rcscn rch Centre, Sreckariyam, Tri vandrum 695 0 17. Kcrala. India

E-mail: mshhau (.trluas.net: msbhalll a yahoo.co.in

Received: 16 October 2000: accepted: 26 March 200 I

The paper reports the studies on eva luation of energy indices of domestic refrigerators of 165 L capacity in India. The specific energy consumption varies between 3.23 and 4. 19 kWh/y/L for single door manual defrost units and between 3.H4 and 4.7X kWh/y/L for double door auto defrost unit s. The major technical areas in a moderni zati on programme arc the usc of alternat ive' to HCFC 22. the introduction of more etTi cient control s and better insulation. Though energy efficient and eco- fricndly domc:-ti c refrigerators arc cost-e!Tcctivc. forces driving technology upgradation such as energy label ing, minimum efficiency standard ' and incentives to industries arc essential to bri ng about renovation in the domestic refrigerator technology.

Introduction

Bansal and Kruger 1 have defined a domestic re­

frigerator as a cabinet or any part or a cabinet that is

des igned for the refri gerated storage of food above 0 "C. has a source of refrigerati on and is intended for house­

ho ld use. Domesti c refri gerators in India and other South

Asian countries form one of the important e lectrica l loads segment in a hou sehold and account for I 0 to 70 per

cent of the allotted domes ti c e lectrica l energy.

The two main issues confronting the re frige rator manufacturers meet the standards of eco-fri endliness and

energy efficiency. In thi s background , a need was fe lt

for rigorous evalu ation of do mestic refrigerators to es­tabli sh base line data on energy consumpti on and its sen­

sitivity to va ri ab les such as age of the machine, ambi ent

temperature and pos iti on of the the rmos tati c contro ll e r.

Domestic refri gerators, in fndi a, are being marketed in various sizes and configurations. The most commonl y used refrigerators are the conventional 165 L single door units with an integra l freezer compartment (29 to 37 L). Compressor motor units of I /8 HP (94 W ) are used as the actuating energy source.

Of late, doubl e door fros t-free refrigerators of 165

L are be ing marke ted . These contain resistance heate rs and blowers to prevent frost formation on the coo les t porti on of the evaporator.

The refri gerant indu stry still uses HCFC 22 as the

work ing fluid though it is slowly g iving way to HCFC 134a.

Evaluation of re fri gerators, si ng le door, as v\'e ll as

doub le door frost-free re fri gerators of 165 L was unde r­

taken. Domes ti c refri gerators of othe r sizes and capaci­ti es were diffi cult to find for conduct in g the con tro lled

ex periments as most of the users had e ithe r one of the

above. A field test set-up was prepared and the energy consumption of the refri ge rators was eva luated.

Bansal and McG ii F have eva luated household re­

frigerators us ing diffe rent testing s tandard s such as In­

te rnation al Standards (ISO), American Nati onal Stan­

dards (ANSI), Japanese Industrial Standards (JIS ). Aus­

tra lian -New Zealand Standards (A ZS) and Chinese ati onal Standards (C S). As pe r ISO the testing pa­

ramete rs are as fo ll ows:

( i ) Ambient temperature: 25/32 ± 0.5 "C

( i i) Re lati ve humidity: 45-75 pe r cent

( iii ) Door opening: No.

(iv) Fresh food zone temperature: 5 "C

A detailed compari son of the va rious s tandard s has

led to convers ion factors for convers ion o f energy data from one standard to another.

592 J SCIIND RES VOL 60 JULY 200 1

Table ! -Temperatures measured in domest ic refrigerator at different control sett ings

Sl No Particul ars Control se tting of the thermostat #I #2 #3

01 No cooling load (minimum temperature) 6.6 3.2 0.4

02 No cooling load (mi nimum temperature) 4.5 0.2 -3.6

03 Door opening after I Os (top of cabinet) 11 .0 8.9 6.8

04 Door open ing after I Os (midd le of cabinet) 11 .2 8.9 6.4

OS Door opening after I Os (bottom of cabinet) 10.0 7.7 0

06 Door opening after I Os (top of cabinet) 12.8 13.4 11 .5

07 Door opening after I Os (middle of cabinet) 12.5 13.5 9.0

08 Door opening after I Os (bot tom of cabinet) 11 .0 11 .7 9.5

09 Temperature immedi ately after loading (bottom of cabinet) 12.9 15.8 5.g

10 Temperature 4 h after load ing (bottom of cab inet) I 0.4 10.8 3.5

Source: Ref 3

James et a/_ 3·4 have conducted de ta iled laboratory

tests on the perfom1ance of domestic refri gerators. Their thrust has been to establi sh temperatures ins ide the cabi­net fo r various settings of the thermostat and various door openings (Table I ). They have addressed follow­ing four queries:

(i) Would a 'spot ' c heck of a ir temperature pro­vide re liable data or would the temperature have to be monitored for a minimum peri od?

(ii) Could the pos itions of maximum and mini ­mum air temperature be eas il y located in any type of refrigerato r?

(i ii ) How muc h attenti on wou ld have to be pa id to door openings, loadin g patte rn s, e tc.?

( iv) Would a 'spot ' check of product temperature prov ide reliable data?

They have concluded that 'spot ' checks of air and product temperature do not prov ide re li ab le data. The max imum and minimum temperature zone cannot be eas ily located _ Lastl y the number and length o f door openings and the quantity, temperature, and food prod­ucts within the refrigerator considerabl y a lte r the time­temperature characte ri sti cs _ Thus, it is inferred that the gross energy index (kWh/month) and the specific en­ergy consumption (SEC) (kWh/y/Liy capac ity) would be re i iable indi cators of the energy e ffic iency of domes­tic refrigerators _ Table 2 g ives the monthly energy con-

sumpti on and SEC of domestic refrigerators in the inte r­nati onal marke t.

Methodology

Sing le door manu al defros ting re frigerato rs and doubl e door auto defrost units, both of 165 L capac ity were tes ted for periods rang ing from one to two months. Digital energy meters (accuracy c lass I , resolu tion: 0.0 1

kWh, 5000 pul ses/kWh, s ing le phase, 240 V AC, 50 Hz, 0-20 A) were bu ilt into a portable test set up. The energy meter was connected be fore t' e vo ltage stab ili ze r be­cau e voltage drops lead to higher currents, which is paid for by the user. Measurement o f amb ien t temperature and relative humidity were al so taken up .

All the re frigerators tested used HCFC22. In view of the change over to eco- fri end ly r fri gerants in the near future the data presently obtai ned can be converted to apply for the other refri gerants by accurat e mathemati-

al mode ls suc h as those by Serral lac h et a/-'

The energy consumption was measured for ~0 d. The load factor (monthl y bas i ~;) was es timated as_

LF = [Energy consumpti n in 30 d] / [Rated power input x 720] .

Load fac tor is taken as an indicato r instead o f com­pressor run time because the power input can be e ither more (due to overloading of product~, excessive current, etc .) or less (due to unde r vo ltage, partial loading, etc.)

BHATT: DOMESTIC REFRIGERATORS 593

Table 2- Comparison of energy consumpt ion of some domestic refrigerators as per ISO

Sl no Model Model Capacity (L) Energy index SEC (kWh/y/L) (kWh/month)

Single door models

01 Hitachi (Japan) RX 717 170 15.0 1.06

02 National (Japan) NR 2 14 R 205 15.8 0.9 3

03 Gram (Europe) K 244 231 16.7 0 .87

04 Electrolux (Europe) RF 930 245 18.3 0.90

05 AEG (Europe) KS 380 330 22.9 0.83

06 Bosch-Siemens (Europe) KK 360 346 24.2 0.84

07 Gram (Europe) KK395 371 26.2 0.85

08 New Zealand unit 370 40.5 1.33

09 Australian unit 420 30.0 0.87

Double door models

10 ational (Japan ) NR 305 HVP 300 22.9 0.92

II M itsubishi (Japan) MR 3 126 3 10 24 .2 0.94

12 Toshiba (Japan) GR4156AS 410 35 .8 1.05

13 National (Japan) NR 434 TR 425 37. 1 1.05

14 Electrolux (Europe) TR 11 20 C 315 39.6 1.5 I

15 Gram (Europe) KF 355 337 45 .8 1.63

16 Whirlpool (USA) ET 17 HK XR 485 62.5 1.55

17 Westinghouse RP 423 420 28.2 0 .80

18 ational NR-B500-W 500 104.1 2.50

19 Fisher & Paykcl c 370 370 39.3 1.27

20 Fisher & Paykcl N 500 B 500 57.3 1.]7

2 1 Dual evaporator with

Lorcnz-Mcutulcr cycle Lab model 222 24.0 1.26

22 Dual evaporator with Mod

Lorenz-Meutuler cycle Lab model 222 25.5 1.34

23 Danish dual refri geration

system 486 43. 3 1.07

594 J SCI IND RES VOL 60 JULY 200 1

Tab le 3- Result s of energy consumpti on tests on single door manual defrosting domes ti c refri gerators of 165 L capac it y

Sl no Parti cul ar Age. Y

01 Refrigerator #1: Load: nil Thermostat

position: minimum Insu lati on: foam ew

02 Refri gerator #1: Load: nil Thermostat

position: maximum Insulation: foam ew

03 Refri gerator # I: Load: heavy Thermostat

position: normal lm.ul ation: foam New

04 Refri gerator# 2: Load: heavy Thermostat

position: normal Insulation : foam

05 Refri gerator #3: Load : heavy Thermostat

position: normal Insulation: glass woo l

06 Refri gerator #4: Load: heavy Thermostat

position: normal Insul at ion: foam 2

07 Refrigerator # 5: Load: medium Therm ostat

positi on : normal Insu lation: foam 4

08 Refrigerator# 6: Load: heavy 14 Thermostat

pos iti on : norm al Insulation: gl:1ss wool 4

09 Refri gerator # 7: Lo:1d: medium Thermostat

position: normal In sul ation : glas' wool 5

10 Refri gerator # 8: Load: medium Thermostat

position: normal In sul ati on: glass woo l H

II Refri ge rator# 9: Load: medium Thermostat

posi tion: normal Insul ation: glass wool X

12 Refri gerator # I 0: load: medium Thermostat

position: normal Insulation: glass wool 10

13 Refri gerator # II : Load: medi um Thermostat

position : normal Insulation: glass wool 10 (a )

14 Refri gerator # 12: Load: medium thermostat

position: normal Insulation: glass woo l 13

Note: Compressor overhaul ed 2 y back

than the nominal rated power input. A hi gh load factor can indicate e ither a high percentage of compressor run time or high power intake by the compressor motor.

Results and Discussion

The results of the tests on the sin g le door manual defrosting refrigerators are gi ven 111

Table 3. The observations are as fo llows:

LF per cent Energy under SEC (k Wh/y/L) (k Wh/month )

64.9 44.4 3.23

70.9 4!:l .5 3.S:l

67 .8 46.4 3. 37

67 .5 46.2 3.36

65 .3 44.7 3.25

67. 1 45.9 3. 34

71.5 4X.9 3.S:i

69.7 47.7 34 7

72.8 49.X 3.62

71.X 49. 1 3.57

72.8 49.8 3.62

84.2 57 .6 4. 19

72.5 49.6 3.61

83.4 57.0 4. 14

( i) Brand new units (within three months of

purchase) consume between 44.4 and 4S.5 kWh/month. The energy consumpt ion does not depend on th brand but on the part icu lar machine.

(ii ) In a brand new unit (with in 3 months o f

purchase), operati on in the low and high thermostat positions re ·ults in consump-

BHATI: DOMESTIC REFRIGERATOR S 595

tion of 44.4 and 48 .5 kWh/month , respec­tivel y.

(iii ) Models with insulation of glass wool and PUF (polyurethane foam ) do not show any difference in their energy consumption. Rather it is the thickness and condition of the insulation that matter.

(iv) In units which are around 4 y old, ther­mostatic controls do not show appreciable difference in energy consumption for the different settings. In units of I 0 y and over, thermostatic controls are generally out of order and are working at a single point.

(v) Increase of the door openings from 15-30 d does not show any appreciable dif­ference in energy consumption of the units.

(v i) Ambi ent temperature variation tn the range of 24 to 32 ac does not show any appreciable difference in the energy con­sumption This is probably due to the fact that the refrigerant is install ed indoors where the local room temperature does not vary beyond 28 to 32 oc. Also, relati ve humidity of the ambient air from 70 to 95 per cent does not affect the energy con-

sumption seriously.

(v ii ) Loading of materials into the unit does not show any serious increase in energy consumption as compared to the unl oaded condition.

(v iii ) Units (single door) which have been used for over I 0 y without any planned main­tenance, consume 57.0-57.6 kWh/month.

(ix ) Units which have been in use fo r over I 0 y with at leas t one overhaul of compres­sor (compressor cut open and re-welded) consume only 49.6 kWh/month . There is a reduction of approxi mate ly 8.0 kWh/ month.

The monthly energy consumption (E) correlates with the period of use (t) as, E= 45.9 +0.91 (t) , where ti s in years and E is in kWh/month.

The results of the tests on the double door auto defrosting refrigerators are given in Table 4. The main observations from thi s are as follow s:

(i) The energy consumption is around 52.8-65 .7 kWh/month. This is higher than the manu al defrostin g sin gle door models because of the presence of the electrical auto defrost heater.

(ii ) Since the technology is of fairl y recent origin, old units could not be identi fied for evaluation

The high load factors in both types of refri gerators

are due to thermostats cutting out over a lower th an de­

sired te mperature and due to the power input of the com­pressor be ing hi gher than its nomin al ratin g (94 W ). In

frost free units, res istance heate rs a lso contribute to the

power input.

Energy Conservation

Thermostatic control s and insul ati on have to a large

ex tent reduced the energy consumpti on of domes ti c re­

frigerators to g ive load fac tors of 60 to 70 per cent How­ever, it can be seen that the SEC of the refrigerators stud­ied is quite hi gh (3 .25 to 4.75 kWh /y/L as compared to

a round 1.0 kWh /y/L for mode ls in the international

market). The motivati on for improv ing energy effic iency and the successful techniques are briefly described be­low.

Geller6 has stated that the SEC o f domestic refrig­

e rators call be reduced through better in sulation , energy

efficient motors, high effi c iency compressors; and larger heat exchangers. He has estimated that d uring the 15 y period between 1970 and 1985, industriali zed count ries

have been ab le to reduce the ir SEC by 30 to 70 per cent based on these measures at an ex tra capital cos t o f onl y 5 to I 5 per cent. Improv ing the energy effic iency of do­mes ti c refrigerators has thu s been cos t e ffective7 . For

example the annu al energy consumpti on for new mod­e ls of 450 L refrigerators dropped from 1990 kWh/y in 1972 to II 50 kWh/y in 1983 and furth e r down to 770 kWh/yin 1990 with an increase in capita l cost of only -to I 0 per centx

596 J SCI IND RES VOL 60 JULY 2001

Table 4- Results of energy consumption tests on double door auto defrosting domesti c refrigerators of 165 L capacit y

Sl No Part icul ar Age, Y

OJ Refri gerator# I: Load: nil thermostat position of freezer: minimum Thermostat position of refrigerator:

minimum New

02 Refrigerator# 1: Load: nil Thermostat position of freezer: maximum Thermostat position of refri gerator:

maximum New

03 Refrigerator# 1: Load: medium Thermostat position of freezer: normal Thermostat position of

refrigerato r: normal New

04 Refrigerator# 2: Load: medium Thermostat position of freezer: normal Thermostat position of

refri gerator: normal New

05 Refrigerator# 3: Load : medium Thermostat position of freezer: normal Thermostat position of refri gerator: normal New

To cite a case, the potential for energy saving

in domestic refrigerators has been analyzed consid­ering the performance of a two-door au to defrost 460 L refrigerator. The energy saving measures and the estimated reduction in energy are given in Table 5. It has been shown that the SEC can be re­duced to 80 per cent of the 1987 level (from 2.53 kWh/y!L to 0.47 kWh/y!L) .

The factors that contributed to the improvement in energy efficiency of refrigerators in the US were the statutory minimum efficiency standards, steep hike in residential energy prices and requirements

of energy labeling9

The most promising options for domestic re­frigerators are dual refrigeration system. evacuated panel insulation (hard vacuum panels about 2.5 mm thick with thin metal skins or soft vacuum panel s containing powders into multi-layer plastic skins) and multiple cooling capacity. European dual refrig­eration systems consume around 30 to 35 per cent

LF (per cent) Energy under SEC (kWh/y/L)

(k Wh/month)

58.6 52.8 3.84

62.0 55.8 4.06

60.6 54.6 3.97

65.0 58.5 4.25

730 65.7 4.78

less energy ( 1.0 kWh/y!L) than their counterparts in the US. 9

Bull ard and Radermache r10 have reviewed the emerging technologies for refri gerators and air con­ditioners . They have stated that the fo rces drivin g technological innovation in the domestic refrigera­tion sector in t e US are the National Appliance Energy Conservation Act (NAECA) of 1987 (which specified minimum energy efficiency standards), the environmental policy (particularly banning ofHCFC 22 from 1996 and statutory decline of HCFC 22 from 2030), the high peak load price of e lectrical energy, the '$ 30 million Goldm Carrot' awards to manu­facturers to produce energy efficient equipment to produce energy efficient equipment and adoption of innovations originating outside the industry 11 (e .g., scroll compressors, digital controls, fuzzy logic based controllers and all aluminum vacuum brazed panels). Table 6 gives the technologies which lead to reducing th e SEC of domestic refrigerators.9 11

BHATT : DOMESTIC REFRIGERATORS

Table 5- Saving potenti al options for a domestic refrigerator of 460L.

SINo Particu lar Energy under SEC

(kWh/month ) (kWh/y/L)

01 Basel inc ( 1987) 97.25 2.54 02 Compressor with energy

cflicicncy rati o of 3.65 8 1.92 2.13

03 Evacuated panels 43.84 1.1 4

04 More efficient fan 40.84 1.06

05 Double freeze gasket 35.58 0.93

06 Compressor with energy

efficiency ratio of 4.50 29.75 0.78

07 Double refrigerati on gasket 26.08 0.68

08 Externa l fan motor 25 .50 0.67 09 Compressor with energy effici ency

rati o of 5.00 21.92 0.57

10 Flottom mounted co ndenser 18.17 0.47

Source: Rcf.7

Table 6- Technologies which lead to reduction in SEC of domest ic refrigerators

Sl o Particul ars Time frame·

0 I Zeotropic refri gerant blends

02 New compression cyc les: Lorenz cycle. Lorcnz-Mcut7ncr cyc le. Modifi ed Lorcnz- Meutzncr cycle L

03 Linear reciprocating compressors. scro ll compressors. oil free compressors M

04 Multi-pressure expansion systems M

05 Internally !luted tu bes. ribbed tubes for evaporator and condenser I

06 Charge optimi zing through falling film cvapormors M

07 t\ir side heat transfer enhancement through more aerodynam ic fins

08 Optimized au to defros t cycles

09 Optimized low cost capill ary tubes and orifi ce pl ates with sucti on li ne heat exchangers

I 0 Vacu um panel insul ati on

II Digital, fuzzy log ic, learning based con trol with variable speed drives for compressor motors.

12

13

14

15

Thermoelectric coo lers

Compression heat pumps with solution ci rcuits

Absorption systems with compact heat exchangers

Diffusion absorption systems

' - I: immediate: M: medium term (5-10 yl: L: long term: over 10 y Source: Ref. 10

L

L

L

M

597

598 J SCIIND RES YOL60 JULY 2001

Turiel and Heydari 12 have considered the im­pact of a large number of design options to improve the efficiency of domestic refri gerators. These in­c lude foam insulation substitution , inc reased thick­ness of insulation , doubl e door gasket, improved

foa ms, vacuum panel insul ation , hi gh e ffi c ie ncy compressors, adaptive defrost, improvements in c ir­cul at ion fans, anti-sweat heater switch , inc reased evaporator surface hybrid evaporators, finning o f

heat transfer area, use of mixed refri gerants, im­proved expansion devices, fluid contro l valve, two compresso r systems, use of natura l convec ti o n cur­rents, optimal location of components and compact layout. They have shown that the annual energy con­sumption came down by a lmost 50 per cent from

I 000 kWh/y (base line) down to about 500 kWh/y.

Thus, it can be said that the energy conserva­tion approach is three-fold: providing inst ituti onal

motivating factors, introduction of energy effic ient technologies, and a pl anned maintenance strategy fo r equipment in use for some time. The first two are a lready discussed above. Energy efficien t tech­nolog ies have proven to reduce the SEC from 3.5 to arou nd 1.0 kWh/y/L. Energy labeling needs to ga in

importance in the Indi an domes ti c househo ld app li ­ance/product market.

Typica l areas where ene rgy can be conserved through pl anned maintenance of domestic refri gera­tors in use for a few years are as fo ll ows: 1

-'· 1 ~

(i) Inte rnal leaks (deteriorat ion in the volumet­ric effici ency) of the compressor take place after about 8 to I 0 y of serv ice. The coo ling does not get affec ted but the e nergy con­sumptio n will be hi gh. It is recommended to cut-open the hermetic unit and overhaul th e compressor.

(i i) Partial loss of refri gerant and the presence of inco nde nsibles such as a ir/nitrogen in the refri gerant circuit due to poor charging lead to lowering of cooling effect without pro­portionate reductio n in energy consumption. In such cases where cooling effect is low or inadequate and the gas must be re-charged.

(iii ) Deterioration of insul , tion of the s ides and front door leading to moisture condensati on on the door and sides causes hi gher energy consumption . Insulat ion must be re in fo rced/

replaced/revamped to prevent cooling of the outer body of the refri gerato r.

(iv) Leakage o f ch ill ed a ir due to deterioration of the door sea l can b·~ red uced by replace­ment of the doo r seal.

( v) Poor thermal response of the thermostats can be a major cause of hi gh energy consump­tio n and can be avoided by rep lacement of the thermostat by a proven o ne. Faulty th er­mostats seldom get not iced.

Planned ma intenance can resu lt in energy conse r­

vation of 8 to I 0 kWh/month or 0.5 -0.73 kW h/y/L. The SEC can be res tored to the baseline.

Eco-Friendly Refrigerants

The strategy towards eco-friend ly refri ge rants is two-fo ld :

(i) Use of zeotropic (non-azeotropi c) refri gerant blends (mixed refrige rants) us in g as HFC 134a!HFC I 52a, in new cyc les. Mixed refrig­erants can he lp in producing s liding tempera­ture differences in the ~vaporato r (in stead of

isothermal coolin g, as at present ) and thus better heat withdrawa l for the same surface area. These have he lped reduce the e nergy

consumption in domestic ref rigerators by I 5 per cent. 15 Use of mixed refrige rants serve the dua l purpose of eliminat ion of HCFC 22 and innovative des ign in refri gera nt techn o logy as de monstrated by Simmons et a/. 11

' Here. mix­tures of propane (R290) and butane (R600) have been used in the Lorenz-Meutzner cycle and Modified Lorenz- Meu tzner cycle for a domestic refri gerator with independent con­trol of the freezer and fre h food compart­ments. The SEC is 1.26 kWh/y/L for the

fo rmer and 1.34 kWh/y!L for th e latter. The insulation foam used in th e above is derived from HCFC 141a.

BHATI: DOMESTIC REFRIGERATORS

(ii ) Use of substitutes such as HHCFC 223, HFC 134a, and HFC 152a, in traditional cycles . Besides eco-friendliness , their spec ific energy consumption is lower by I 0 to 12 per cent than

HCFC 22.

For countries in the Indi an sub-continent the latter approach is an immediate so lution to tide over the lacuna created on account of the ban on refrig­erants with high ozone depleting capacity. In the long range the former approach will be more rewarding.

Conclusions

The mam conclusions of the stud y are as

fo llows:

(i) Single door 165 L refrigerators consume as much as 44.4-57.6 kWh/month (SEC: 3.23-4.19 kWh/y/L) . Frost-free models of the same capacity consume between 57 .8 and 65.7 kWh/month (SEC: 3.84-4.78 kWh/y/ L). The SEC is higher by almost 3 .5-times than that in industri ali zed countries that have succeeded in red ucing their SEC to be low 1.0 kWh/y/L.

(ii ) The energy consumption of the units is not brand spec ific but depe ndent on the indi­vidual unit.

(iii) Units using g lass wool and PUF (po lyure­thane foam) do not show any apprec iable difference in energy consumption. Also, the energy consumption is not sensitive to am­bient temperatures between 24 and 32 "C and relative humidity range of 70 to 95 per cent.

(iv) Brand new units do not show any difference in power input than units purchased 2 to 3 y back. However, units in use for over I 0 y and not overhauled/repaired since purchase show a marked deterioration in energy con­sumption (0.9 1 kWh/monthly of operati on higher th a n the baseline of 45.9 kWh/ month).

(v) Immediate areas for energy conservation are: re-insulation of door and sides, replacement of door gaskets, compressor overhaul by cutting open of hermetic sealing and replace­ment of piston rings; overh aul of moto r, minimi zing incondensibles (like nitrogen, moi sture and air) in the refrigerant circuit ;

optimal gas charging, replace me nt of ther­mostat, etc . These offer iucentives of e nergy conservation of around 0 .58 to 0.73 kWh/ y/L.

(v i) Thermostats strongly affec t the energy con­sumption of the refrigerators. Logic based control strategies to matc h the output of the refrigerator with the load and use of better insul at ion, offer the best incentives for cost effecti ve reducti on in energy consumption in the near future. The SEC can be reduced to around 3.5 kWh/y/L to about 1.0 kWh/ y/L

(v ii ) It is time fo r the refrigerat ion industry in the Indi an sub-continent to think in terms of energy labeling, change over to eco-friendly, energy effic ient refrigerators in the near fu­ture.

(v iii ) Incenti ve schemes to encourage ene rgy-d·­ficient refrigerators such as those prov ided by utilities in Weste rn countri es can stimu­late the industry and interest the users.

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600 J SCI IND RES VOL 60 JULY 2001

usage to new refrigerants, I I F-1 I R Commission E2 with EI. 81, 82-Melboume, Australi a ( 199611 ).

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