SUCCESSFUL CONVERSION TO NON-ODS REFRIGERATION

CASE STUDIES

SUCCESSFUL CONVERSION TO NON-ODS REFRIGERATION

THE NEW ZEALAND EXPERIENCE

August 1995

UNEP Industry & Environment OzonAction Programme

SUCCESSFUL CONVERSION TO NON-ODS REFRIGERATIONTHE NEW ZEALAND EXPERIENCE

1

ACKNOWLEDGEMENTS

This document was written jointly by Dr Nevin Amos from the Meat Industry Research Instituteof New Zealand (Inc) (MIRINZ) and by Alan Baldwin and Roger Keedwell of the New ZealandDairy Research Institute, for UNEP Industry and Environment Office.

For the first case study reported our thanks go to Wattie Frozen Foods Ltd, Feilding, NewZealand, for allowing their site to be used for the case study; Chilltech Refrigeration andElectrical Specialists, Palmerston North, New Zealand, for performing the conversion; and theNew Zealand Foundation for Research, Science and Technology who funded the conversion.

DISCLAIMER

The United Nations Environment Programme, Industry and Environment office and itsemployees, and the reviewers of this document and their employees do not endorse theperformance, worker safety or environmental acceptability of any of the technical optionsdecsribed in this document.

While the information contained herein is believed to be accurate, it is of necessity presentedin a summary and general fashion. The decision to implement one of the alternatives presentedin this document is a complex one that requires careful consideration of a wide range ofsituation-specific parameters, many of which may not be addressed by this document.Responsibility for this decision and all of its resulting impacts rests exclusively with theindividual or entity choosing to implement the alternative.

The United Nations Environment Programme, Industry and Environment office and itsemployees, and the reviewers of this document and their employees do not make any warrantyor representation, express or implied, with repsect to its accuracy, completeness or utility; nordo they assume any liability for events resulting from the use of, or reliance upon, anyinformation, material, or procedure described herein, including but not limited to any claimsregarding health, safety, environmental effects, efficacy, performance, or cost made by thesource of the information.

The lists of vendors made provided in this document are not comprehensive. Mention of anycompany, association, or product in this document is for information purposes only and does notconstitute recommendations of any such company, association of product, express or implied,by UNEP, Industry and Environment office, and its employees, and the reviewers of thisdocument and their employees

UNEP Industry and Environment Office, January 1995


2

TABLE OF CONTENTS

Acknowledgements

Disclaimer

Introduction

Case Study I - Cold store conversion to R507

Case Study II - Farm vat refrigerant replacement

Appendix A - Conversions undertaken within New Zealand


3

INTRODUCTION

Mounting scientific evidence has implicated chlorofluorocarbons (CFCs), hydrofluorocarbons(HCFCs), halons and methyl bromide in the depletion of the stratospheric ozone layer of theEarth’s atmosphere, which protects animal and plant life from the damaging effects ofultraviolet radiation. In September 1987, nations concerned about this crisis signed theMontreal Protocol, a landmark agreement that identified the major ozone depleting substances(ODSs) and established a timetable for their eventual phase-out. Under the Montreal Protocol,ODS production and consumption are to be reduced and ultimately eliminated through thedevelopment of chemical substitutes and the use of alternative manufacturing processes,recycling, recovery and reclaiming procedures.

The Multilateral Fund was established in 1991 to assist developing countries that are Partiesto the Montreal Protocol in their conversion to ODS alternative technologies. As one of theFund's Implementing Agencies, UNEP is assigned the responsibility of conducting research,gathering data, and providing a clearinghouse function. One of the clearinghouse service UNEPprovides to meet the information needs of developing countries is a series of sectoral casestudies that provide recent and specific information on industry's successful changeover to non-ODS technologies and substances.

As one of the significant ODS consumption sectors, refrigeration has been using CFCs asrefrigerants since their introduction by DuPont in the 1920s. They have been widely used indomestic refrigerators, air conditioning, commercial refrigeration systems, cold storage, foodprocessing and mobile air conditioning. Countries with a large reliance on agricultural exports,such as many developing countries, have been using CFC refrigeration technologies toguarantee the cold chain from production through to the market, to ensure product quality.Measures need to be put in place to ensure that developing countries have the appropriatetechnology, and expertise to maintain these cold chains, with the upcoming phase-out of CFCrefrigerants.

As a producer of agricultural products for export to distant markets, New Zealand is similar tomany developing countries in that it relies heavily on refrigeration for the storage andpreservation of such products. Large numbers of CFC- and HCFC-based refrigeration systemsare used in the food processing industries within New Zealand (Table 1). As a signatory of boththe Montreal Protocol and its subsequent amendments in London and Copenhagen, NewZealand is committed to phasing out new CFC-based refrigeration systems by 1 January 1996.Following on from the CFC phase-out, hydrochlorofluorocarbons (HCFCs) will also be phasedout in New Zealand by 2015.

Industries within New Zealand using CFC-based systems have the options of relying on storedCFC supplies until the end of the useful life of the refrigeration system, converting the CFC-based system to an alternative non-ozone depleting refrigerant, or replacing the existing systemwith a new system using an acceptable refrigerant.


4

In general, reliance on stored or recycled CFC refrigerant is viable only for small hermeticsystems, which usually operate for many years free of problems, have small refrigerant chargesand are typically difficult to retrofit with non-CFC refrigerants. Most larger systems use openor semi-hermetic compressors. These are more difficult to seal and consequently are morelikely to leak. Thus, reliance on stored or recycled CFC refrigerant is less attractive for thesesystems, as stocks are expected to quickly become depleted.

Conversion to some of the most favoured alternatives requires that the original CFC charge bepresent when flushing oil from the system. Problems may be encountered if conversion is lefttoo late and the system suffers catastrophic failure, resulting in total loss of the CFC refrigerantcharge.

Conversion from the existing CFC-based refrigerant to an alternative non-ozone depletingrefrigerant is the most viable long term solution for CFC-based refrigeration systems notnearing the end of their useful life. In general, systems under 15 years old, that use open orsemi-hermetic compressors are considered retrofittable. Table 1 lists the number of CFC andHCFC systems within the food processing industries in New Zealand in 1994. A largeproportion of these systems could be retrofitted with non-ozone depleting alternatives. Thosethat were considered to be not retrofittable either were more than 15 years old, in which casethe CFC could be converted to an alternative refrigerant at the same time as the system isreplaced, or contain hermetic compressors.

Table 1. CFC and HCFC usage in New Zealand food processing industries (as surveyedby The Meat Industry Research Institute of New Zealand Inc. (MIRINZ), 1994)

Food Sector CFC-R12 R502 R22

No of Total % No of Total % No. of Total %

systems mass systems mass (t) systems mass (t)

(t)

1 1 1

Processing

Meat 700 15 70 400 25 84 940 100 74

processing

Fish 400 8 77 450 31 95 400 77 69

processing

Beer & wine 170 2 45 20 1 100 200 14 92

Processed 680 8 64 600 32 89 700 34 95

foods


5

Cold chain

Horticultural 100 8 69 0 0 0 350 22 100

cool storage

Cold storage 1100 8 100 140 9 100 50 17 81

& transport

Dairy 14000 136 - 0 0 - 360 36 -2

Outlets

Supermarket 2400 83 85 700 53 72 540 76 100

s

Wholesale

fruit & vege

markets

Other retail

600 19 76 25 <1 0 190 15 0

44000 51 16 8000 13 20 4000 25 55

1. Percentage retrofittable, based on a 15 year operating life and excluding all systems with hermetic

compressors

2. Figures supplied by the New Zealand Dairy Research Institute

The case studies that follow describe the conversion of two operational CFC-based systems tonon-CFC alternatives. The first outlines the conversion of a vegetable cold store R502refrigeration system to R507, the second describes the conversion of an R12 dairy milk vat toa Du Pont HCFC ternary blend. The objectives for both of these case studies were to determineif recommended retrofit procedures were adequate and to assess the change in systemperformance after retrofitting. Results obtained from these case studies should be readilytransferrable to countries where operating conditions are similar to those found in New Zealand(temperate climate with average daily max/min temperatures of about 25/10 in summer and15/0 in winter). For countries with different operating conditions, whilst the retrofit procedureswould still be the same, changes in operating performance after retrofitting may be different dueto differences in operating temperatures and pressures.

In addition to the case studies, known conversions undertaken to date within New Zealand arelisted in the Annex.


6

CASE STUDY ICOLD STORE CONVERSION TO R507 GOES SMOOTHLY

BackgroundNew Zealand relies heavily on refrigeration for storing and transporting it’s agriculturalproducts to world markets. Food industry refrigeration systems range from small hermeticsystems, providing less than 1 kW of refrigeration capacity, to large industrial systems,providing hundreds of times that capacity.

New Zealand has followed the world trend towards using man-made chlorofluorocarbon (CFC)and hydrochlorofluorocarbon (HCFC) refrigerants in many of its refrigeration systems.Although a number of large industrial refrigeration systems operate on non-fluorinatedalternatives such as ammonia, a large proportion of systems in food processing industries useR502 in low temperature freezing and cold storage applications. In 1994 the Meat IndustryResearch Institute of New Zealand (MIRINZ) surveyed New Zealand food processing industries(excluding dairy operations) and found that in total they use about 200 tonnes of R502 (46 ODPtonnes) (Table 1). Most of the R502 tonnage is used in the meat and fish processing industriesand in supermarkets. It is estimated that more than 70% of these systems can be retrofittedwith an non-ozone depleting alternative refrigerant. The remaining 30% of systems are eitherhermetically sealed or are too old to make retrofitting economic.

MIRINZ undertook a conversion of a vegetable cold store R502 refrigeration system to the non-ozone depleting R507 in October 1994, at Wattie Frozen Foods Ltd, Feilding, New Zealand.This conversion was done to test whether the refrigerant manufacturer’s retrofit guidelines andthe performance of the alternative refrigerant were satisfactory under New Zealand conditions.This case study reports the results obtained from that conversion. The results obtained fromthis work should be readily transferrable to developing countries.

EquipmentThe plant retrofitted in this trial was built in 1978, and was operating on a vegetable cold storerunning at -18 C air temperature. The system incorporated two Muller-McAlpine evaporators

o

(model MUA4400), each fitted with three 180 W fans. The compressor was a Bitzer 6H, fittedwith a 15 kW motor, and it had undergone a major overhaul two years previous to the retrofit.Although the plant was 17 years old, the compressor overhaul meant that the compressor wasequivalent to being 2 years old; hence it met the retrofit requirement of being less than 15 yearsold. The system used an evaporative condenser. To monitor the system performance before andafter the retrofit, the system was instrumented with temperature, pressure, flow and powertransducers to measure system characteristics (Figure 1).

Refrigerant selectionThe criteria for selection of the refrigerant to be used were that it should be non-ozonedepleting, it should be able to be retrofitted into an existing R502 system, and it should becommercially available. Table 2 lists the refrigerants available commercially in New Zealandas R502 replacements at the time of the conversion. The alternatives included hydrochloro-


7

fluorocarbons (HCFCs), like R22, hydrofluorocarbons (HFCs), and blends containing HCFCsand/or HFC refrigerants.

R22 has been used in New Zealand in a number of new installations as an alternative to R502.However, it, along with other HCFC refrigerants, will begin to be phased-out in New Zealandas early as the year 2000, and phase-out will be complete by 2015. Thus it was not seen as along-term solution. Refrigerant blends containing HCFC refrigerants will also be phased-outin New Zealand, so they too were not considered as viable long-term replacements.

Figure 1: Schematic diagram of the refrigeration system and the measurement positions usedduring the retrofit.


9

Table 2. R502 substituts refrigerants available commercially in New Zealand(Chadderton et al., 1994)

Refrigerant R502 R402A R403B R404A R407B R507

Trade name 502 Suva® Isceon® Suva®H Klea® AZ50HP80 69L P62 61

Chemical type CFC HCFC HCFC HFC HFC HFCazeo- zeotrope zeotrope zeotrope zeotrope azeo-

trope1

2

trope

ODP 0.23 0.03 0.03 0.00 0.00 0.00

GWP (direct) 3.74 0.63 4.09 1.00 0.70 0.96

Boiling point -46 -49 -50 -47 -47 -46( C)o

Temperature 0.0 1.6 — 0.5 3.0 0.0glide ( C)

o 3

Capacity 1.00 1.03 1.14 1.02 1.04 1.08ratio

4

Efficiency 1.00 0.98 1.00 0.97 0.96 0.95ratio

4

Discharge 0 0 -2 -7.4 -5 -8temp. ( C)

o 4

Recommended MO AB x 1 MO EO x 3 EO x 3 EO x 3oil

5

Refrigerant 1.0 1.5 1.5 1.5 1.5 1.5cost (ratio)

6

1. Azeotropes are mixtures whose boiling point and hence composition do not change as vapour isgenerated on boiling.

2. Zeotropes are mixtures whose boiling point and composition change as vapour is generated onboiling.

3. Temperature glide is the difference in boiling point between the onset and completion of evaporationfor zeotropic mixtures.

4. Comparison at -32 C evaporating, 43 C condensing, 18 C return gas.o o o

5. MO = mineral oil; EO = ester oil; AB = alkylbenzene lubricant. Recommended number of flushesindicated.

6. Compared to R502 and based on approximate cost to refrigeration service companies (March 1995).


10

R507 was selected for retrofitting because of its non-ozone depleting nature (i.e. ODP = 0), andalso because it is azeotropic. Being an azeotrope means it has constant evaporation andcondensation temperatures, at constant pressures, and refrigerant leakage will not result in theremaining refrigerant changing in composition.

Retrofit procedureThe retrofit was carried out in accordance with the refrigerant manufacturer’s (Allied Signal)recommended procedures, which involved:

� Isolating the R502 charge by pumping the system down; � Selecting a suitable polyol ester oil that is compatible with the compressor, (Mobil EAL

Arctic 32 was selected as being suitable for this system); � Removing the existing mineral oil lubricant and recording the volume of oil removed; � Recharging the compressor with the same volume of polyol ester oil as the volume of oil

removed; � Recharging the system with R502 and running the compressor for at least 24 hours. The

compressor was run for 24 hours following the first and third flushes, and for 48 hoursfollowing the second flush due to service personnel unavailability;

� Repeating the last three steps until the residual mineral oil content was below 5%; � Removing the R502 charge and recording the mass removed; � Evaluating the expansion device (most R502 expansion valves will operate satisfactorily

with R507; capillary tube systems require replacing). The systemstudied had an existingR502 expansion valve. This was not replaced and has operated satisfactorily on R507;

� Replacing the filter-dryer with one compatible with R507 (A Virginia KMP Corp., Type

VS48H filter-dry er was used); � Evacuating the system from both sides to a full vacuum of 1000 microns or less; � Checking the system for leaks, then charging the system with R507 (initially 75% by

weight of the original R502 charge, and increasing in 5% increments until the system isfully charged). The charge will typically be about 85% by weight of the original R502charge;

� Resetting the high pressure cutout to compensate for higher discharge pressures if


A measured volume of oil mixture is added to 10 volumes of methanol, mixed, and the1

residualmineral oil which forms a separate layer can be determined.

A refractometer measures the refractive index of a compound. The refractive index of a2

mineral oil-polyol ester oil mixture is highly correlated with the percentage mineral oil inthe mixture.

11

necessary (not found to be necessary in the system studied).

The retrofit ran smoothly in accordance with these recommendations. In general, three oilflushes are recommended to reduce the mineral oil concentration below 5%. However, fourflushes were required, for the system studied. This was attributed to low points in therefrigerant piping which may have impeded oil return.

During the conversion, oil samples were analysed for mineral oil content using the methodproposed by Carpenter (1982) . Additional samples were taken and rechecked with a

1

refractometer after the conversion was complete. Carpenter’s method consistently under2

predicted the mineral oil content with respect to the more accurate refractometer readings. InNew Zealand, Carpenter’s method is often used in the field by refrigeration service engineers,and if similar trends to those observed in this work occur, then some converted systems may beoperating with a mineral oil concentration higher than the recommended level (< 5%). In futureconversions, including conversions in developing countries, a refractometer should be used formore accurate results, or the acceptable mineral oil concentration should be lowered (< 3%) ifCarpenter’s method is to be used.

Results and discussionThe performance of the system retrofittedwith R507 compared favourably with that of theoriginal system running on R502. Table 3 shows mean measured system parameters before and after the conversion.

Discharge and suction pressures were slightly higher and discharge temperature and refrigerantmass flow rate were lower for the R507 system than for the R502 system. Compressorperformance increased by about 7% after the conversion. Heat exchanger performanceincreased by up to 20% which may have contributed to an improved system C.O.P.

EconomicsIn total the conversion cost US$4,500 (December 1994 prices). Refrigerant made up 58% ofthis cost; hence, small changes in refrigerant pricing will significantly influence total cost. Theextra oil change added about 5% to the conversion cost.

ConclusionsA vegetable cold store R502 refrigeration system was successfully converted to R507 over aone-week period. Recommended procedures for converting from R502 to R507 were followed


12

with no major problems. However, to reduce the mineral oil concentration below 5%, four oilflushes were needed for the system studied rather than the recommended three. The extraservice personnel time and oil associated with the fourth oil change increased the total cost byabout 5%. Oil compositional analyses raised real doubt over the accuracy of Carpenter’smethod, and if this accuracy is indeed in question some converted systems may be operatingwith mineral oil concentrations in excess of recommended levels.

Operation of the system with R507 has been without problems so far. Discharge and suctionpressures were higher, and discharge temperature and refrigerant mass flow were lower for theR507 refrigerant than for the original R502 refrigerant. Compressor performance has beenconsistent with expectations. Gains in heat exchanger performance appeared to occur, and thesemay have contributed to improved plant COP.

Table 3 Mean system operating characteristics before and after the conversion

Parameter R502 R507

Evaporator 1.67 2.01performance (kW/ C)

o

Condenser performance 1.08 1.31(kW/ C)

o

Discharge pressure 14.4 15.7(Bar, absol.)

Discharge temperature 84.7 81.3( C)o

Suction pressure (Bar, 1.89 1.95absol.)

Suction temperature 4.5 4.5( C)o

Refrigerant flow (kg/s) 0.151 0.134

Heat load removed 19.2 20.5(kW)

Compressor power use 11.6 11.4(kW)

C.O.P. 1.66 1.79


13

Industrial refrigeration users in developing countries can have confidence in using the manu-facturer’s recommended procedures for retrofits from R502 to R507. Care must be taken thatthe method used to determine the residual mineral oil concentration is accurate. Under oper-ating conditions similar to those described in this case study developing countries can expect,a similar or slightly enhanced system performance when retrofitting from R502 to R507.

ReferencesCarpenter, N.E. (1992). Retrofitting HFC-134a into existing CFC-12 systems. Int. J. Refrig.,15(6): 332-339.

Chadderton, T.; Shaw, D.; Cleland, A.C. & Carrington, G. (1994). The CFC File, Issue 2, ISSN1172-4927.

ContactsDr N.D. Amos:Research Engineer,Refrigeration and Energy Group,MIRINZ, P.O. Box 617,Hamilton,New Zealand.Ph: (64-7) 855 6159fax: (64-7) 855 3833

Refrigerant R507 SupplierAllied Signal Chemicals, P.O. Box 1052, Morristown, NJ 07962-1053, U.S.A.


14

CASE STUDY TWOFARM VAT REFRIGERANT REPLACEMENT

NEW ZEALAND DAIRY INDUSTRYBackgroundThe dairy industry in New Zealand consists of 15 supplier owned co-operative companiesprocessing the milk of 14 500 dairy farmers (1994 figures). Refrigeration equipment installedon farm vats is in some cases owned by the dairy company and in other cases owned by theindividual farmers. This equipment is used to chill the milk after harvesting in order to inhibitthe growth of microorganisms and to enable safe food products to be made. Work on farm vatrefrigeration has been undertaken by the New Zealand Dairy Research Institute (PalmerstonNorth) which is the central research organization for the New Zealand dairy industry. The workundertaken has been to test replacements for ozone depleting refrigerants in farm vat systems.Findings from these tests should be directly applicable to dairy farm vats in developingcountries.

EquipmentMilk is refrigerated in the vat by passing refrigerant through a double skin floor (evaporator).Figure 1 shows the vat floor construction in cross-section: two sheets are spot welded togetherat dimples pressed into the lower sheet to form the evaporator. The refrigeration compressoris generally of semi-hermetic design with an air-cooled condenser.

Figure 1. Cross section of vat floor.

In this work, a milk vat of 2250 L capacity, previously used, was connected to a Prestcold(Model S200) compressor. A schematic of the general arrangement of the milk vat andassociated refrigeration unit is shown inFigure 2. The vat was set up in a refrigerationworkshop. Refrigerant temperature and pressure sensors were placed in the refrigerant circuitat locations indicated in the diagram (Figure 2) and a transducer was installed to measure thepower demand (kW) of the compressor motor.


15

Figure 2. General layout of farm vat and associated refrigeration equipment.

Refrigerant SelectionThe refrigerant used in most milk vats is R12, a chlorofluorocarbon (CFC) with an ozone-depleting potential (ODP) of 1. This refrigerant will not be available after 1995 and areplacement will be required to serviceexisting installations. Options for replacement of R12were R134a or Suva® MP33.

MP33 is a refrigerant mixture supplied by the Du Pont Company, consisting of threerefrigerants (R124, R152a, R22) with an ODP of only 0.03.

The oil recommended for use with MP33 is an alkylbenzene. This oil and the blend refrigerantsare miscible with the mineral oil that has historically been used with R12. Thus a conversioncan be accomplished with a single oil change or alternatively with no oil change at all.

In contrast, R134a, a hydrofluorocarbon (HFC) refrigerant (with an ODP of 0) requires asynthetic ester oil because it is immiscible with mineral oils. With R134a, up to three ester oilchanges, with operating time in between, may be required to dilute the mineral oil to acceptableoperational limits, normally quoted as 1% residual mineral oil.

The compatibility of MP33 with different lubricating oils is a distinct advantage whenretrofitting. Accordingly MP33 was selected for further investigations; there were, however,two major concerns to be addressed in replacing R12 with MP33:

(1) There should be no reduction in chilling rate as a consequence of the change,otherwise milk quality could be jeopardized;


16

(2) As the mixture is not an azeotrope, the higher pressure refrigerant in the blend[R22, a hydrochloroflurocarbon (HCFC)] was expected to leak preferentially, whichwould alter the ratio of the constituents. When the refrigerant is topped up after aleak, the composition will not be fully corrected, which could have a detrimentaleffect on refrigeration performance.

Retrofit ProcedureThe performance of the cooling system was determined by recording the time required to pull down the

temperature of a measured quantity of water from 21 to 5°C. (Because of the value of the raw material, tests on

farm vats are generally carried out on water rather than milk.)

Initially two tests were carried out on the vat running with refrigerant R12. The R12 was thendrawn off into a refrigerant storage cylinder. At this stage, the mineral oil in the compressorsump could have been drained and replaced with alkylbenzene oil but in these performancetrials the mineral oil was retained. The refrigerant drier in the liquid line was replaced witha type recommended for MP33 (solid core type) and the system was charged with MP33. Theexpansion valve was not replaced or adjusted prior to start-up of the equipment. The chillingperformance on the blend was then assessed using the same procedure as detailed above.

After two tests of the performance of the MP33 as supplied, the effects of refrigerant leakagewere investigated. Half the charge was leaked out of the system, the system was recharged andthe refrigeration performance was determined. This leakage and recharge procedure wascarried out three times. Gas chromatography was used to determine the proportions of theleaked refrigerant gases in samples taken from the collection cylinder; these data, combinedwith the masses of the leaked and recharge gases, were used to calculate the composition of thegas in the refrigerant circuit.

Results and DiscussionAs the leak trials progressed, the proportion of R22 in the system reduced steadily and theproportion of R124 increased (see Table 1). A final sample taken from the liquid in therefrigerant receiver showed proportionsof components in the liquid were similar to thecalculated figures for the system (liquid and gas).


17

Table 1. Blend refrigerant component mass ratios

Component mass ratio (%)

R22 R152a R124 Total

As supplied by Du Pont 36 24 40 100

Refrigerant after 33.4 24.8 41.9 101.1in system recharge

1

1

after 31.7 25.0 43.3 100 recharge

2

after 31.0 24.8 44.2 100 recharge

3

Liquid in refrigerant 30.3 24.1 46.5 100.9receiver after thirdrecharge

2

. By calculation�

The results of the performance tests are set out in Table 2. The efficiency (COP) of therefrigeration system with the blend was slightly higher than that of the system operating on R12.The COP was also improved after the system leaks; however, the performance was measuredat slightly lower ambient air temperatures, in which case the compressor would have had aslightly lower pressure to work against.

Correcting the refrigeration capacity for ambient temperature variations, showed that thecapacity on the blend was slightly higher than that on R12; after the first leak and recharge, theperformance fell to just below that of R12; after the third leak and recharge, the blend capacitywas reduced slightly more to about 2% below that of R12.


18

Table 2. Refrigeration performance data for R12 and MP33.

Test R12 Blend Blend

Test number 1 2 1 2 1 2 3

Air 25.5 26.6 23.6 26.4 22.0 21.5 23.5temperature(°C)

COP 2.38 2.32 2.48 2.40 2.56 2.59 2.52

Refrigeration 5.96 5.95 6.04 6.01 5.89 5.88 5.82Capacity(kW)

1

Adjusted, based on compressor performance data, to an ambient temperature of 24°C.1

Careful selection of materials for the components of refrigeration systems, such as bearings,motor windings, piping circuit components and lubricating oil is required to ensure thecompatibility of the various materials under actual operating conditions. It is critical thelubricant be formulated to ensure a long compressor life if the system is to be reliable. TheMP33 and the alkylbenzene oil are compatible with the mineral oil and existing systemcomponents.

Only a single oil change is required with MP33 because of its tolerance of mineral oil. Therefrigerant drier should be changed but the expansion valve and other system components canbe retained. Thus there are significant reductions in technician time a t conversion, which haseconomic advantages (discussed below). The converted vat has been shown to have a chillingperformance as good as that with the ozone-depleting R12. In addition, the performance hasbeen demonstrated not to be significantly affected by leaks, which change thecomposition of theblend. Three leaks were simulated and it is considered unlikely that three such events wouldoccur in the lifetime of a converted vat.

EconomicsThere is usually little difference in cost between MP33 and the alternative R134a refrigerant;however, the former has lower costs for the conversion labour and materials [MP33 - US$400versus R134a - US$650 (1994)] which makes it attractive .

The MP33 itself will need to be replaced if an HCFC phase-out regime is adopted in the countryof use. However, in situations such as farm refrigeration systems, in which long equipmentlifetimes of 15-30 years are experienced, the more difficult changeover is delayed for manyyears. Thus the extra conversion costs are delayed with consequent economic benefit. On the


19

majority of farms, within the time interval gained, the compressor is likely to wear out and needreplacement, allowing conversion at that time.

Field ConversionsWith the successful outcome of the workshop trials, the decision was made to proceed with theretrofit of 10 farm vats in the field. Oil samples for analysis were taken regularly from thesevats to indicate wear or material incompatibility problems. The 10 refrigeration systems havecompleted 2_ years of normal operation without any failures or lubrication problems.

ConclusionsMP33 blend gives good refrigeration performance in a dairy farm vat system. The refrigerationsystem has been shown to be robust; blend component changes after 3 leaks and recharges havelittle impact.

MP33 is compatible with the existing mineral oil used in the refrigeration circuit. Thus the needfor a sequence of oil flushes at the time of refrigerant change over is eliminated. This is a majoradvantage in the agriculture sector in which farms are remote from service centres. Thesimplicity of an MP33 conversion, arising from its compatibility with existing oils, commendsits use in developing countries.

ContactsNew Zealand Dairy Research InstituteA J BaldwinProgramme Leader, Engineering, Technical Services Section.R W KeedwellSenior Technical Officer, Technical Services Section.New Zealand Dairy Research InstitutePrivate Bag 11 029, Palmerston North, New ZealandPhone (64 6) 350-4649Fax (64 6) 356-1476

Refrigerant SupplierDu Pont ChemicalsFluorine DivisionCustomer Service Centre, B15305Wilmington, DE 19898USAPhone (1 302) 773-0123Faxsimile (1 302) 774 1084

$33(1',; $

&219(56,216 81'(57$.(1 :,7+,1 1(: =($/$1'

7KH IROORZLQJ OLVW JLYHV 5�� DQG 5�� FRQYHUVLRQV XQGHUWDNHQ LQ WKH WKUHH PDLQ FHQWUHV ZLWKLQ 1HZ

=HDODQG XS WR 0D\ ��

$8&./$1' $5($

&RPSDQ\ &RQWDFW DGGUHVV 3KRQH�)D[ 1R� &RQWDFW SHUVRQ 5�� FRQYHUVLRQV 1XP 5�� 1XPEHU

EHU FRQYHUVLRQV GRQH

GRQH

$EE 6WDO 5HI� �� 3DUNH\ SK �� 7LP &DGHOO 5�� WR 5��$ � 5�� WR 5��

/WG� 'ULYH 0DLUDQJL ID[��

%D\ $XFNODQG

1HZ =HDODQG5�� WR 6XYD� � ��

03��

.RROLQH 5HI� �� +XLD 5RDG SK �� 6WHYH &DVWOH 5�� WR 6XYD� � 5�� WR 5��

1= /WG� 2WDKXKX ID[ �� 03��

$XFNODQG

'HVLJQ $LU �� 0D\V 5RDG SK �� -RKQ :LOOLDPV 5�� WR 6XYD� � ��

5HI� 03��2QHKXQJD ID[ ��

$XFNODQG 5�� WR 6XYD� �

03��

5�� WR 5��

7HPSULWH 5HI� 32 %2;�� SK �� 5HLG :KHDWILHOG 5�� WR 5�� 5�� WR 5��

$XJN� /WG� 0DQDNDX &LW\ ID[ ��

$XFNODQG

+DPLOO 5HI� �� )UDQFH 6W� SK �� %LOO +DPLOO 5�� WR 6XYD� ��

/WG� 6RXWK ID[ �� 03��

$XFNODQG &HQWUDO

$XFNODQG

)LQQHPRUH 8QLW $ SK �� %ULDQ +RUULFNV 5�� WR 6XYD� ��

5HI� /WG� :LOOLDP ID[ �� 03��

3LFNHULQJ 'Y�

1WK� +DUERXU

,QGXVW�3N�

$XFNODQG

:(//,1*721 $5($

&RPSDQ\ &RQWDFW 3KRQH�)D[ 1R� &RQWDFW 5�� 1XPEHU 5�� 1XPEHU GRQH

DGGUHVV SHUVRQ FRQYHUVLRQV GRQH FRQYHUVLRQV

&RZOH\ 5HI� �� 3RUW 5RDG SK �� 5�� WR ��$ �� 5�� WR 5��

6HDYLHZ ID[ ��

:HOOLQJWRQ

1HZ =HDODQG

5�� WR $=��

5�� WR 6XYD� � ��

+3��

5HIFR 5HI� 32 %R[ �� SK �� 5REHUW (YDQV 5�� WR 5��

.DURUL QR ID[

:HOOLQJWRQ

1HZ =HDODQG

+DUERXU &LW\ 32 %R[ �� SK �� 7UHYRU 5�� WR ��$ ��

5HI� 1HZODQGV QR ID[ )DUUDU

:HOOLQJWRQ

1HZ =HDODQG5�� WR 6XYD� ��

03��

:DONHU 1\ODQG 32 %R[ �� SK �� %UXFH 5�� WR 6XYD� � ��

5HI� /WG 3HWRQH ID[ �� :DONHU 03��

:HOOLQJWRQ

1HZ =HDODQG 5�� WR ��$ �

5�� WR 5��

+D\ *LEERQV 32 %R[�� SK �� &KULV 5�� WR ��$ �� 5�� WR ��$ ��

5HI� /WG 3HWRQH ID[ �� *LEERQV

:HOOLQJWRQ

1HZ =HDODQG

&+5,67&+85&+ $5($

&RPSDQ\ &RQWDFW 3KRQH�)D[ 1R� &RQWDFW 5�� FRQYHUVLRQV 1XPEHU 5�� 1XPEHU

DGGUHVV SHUVRQ GRQH FRQYHUVLRQV GRQH

$LUG\QDPL[ ��( %ULVEDQH 3K �� 5REHUW 5�� WR 5��$ �� 5�� WR �

/WG� 6W� :\DWW 6XYD� +3��

&KULVWFKXUFK

1HZ =HDODQG

ID[ ��

6QRZWHPS �� 0RQWUHDO 7HUU\ 5�� WR 5��$ � ��

/WG� 6WUHHW %DVWLRQ

&KULVWFKXUFK

1HZ =HDODQG5�� WR 6XYD� �

03��

$EE 6WDO &QU� SK �� *UDKDP 5�� WR 5��$ � 5�� WR ��

5HI� /WG 0RRUKRXVH ID[ �� *UHHQ 6XYD� +3��

$YH

DQG /LQFROQ

5RDG

&KULVWFKXUFK

1HZ =HDODQG

5�� WR 6XYD� � 5�� WR ��

03�� 5��

&RROULWH �� 6W� SK �� %UHQW %DLUG 5�� WR 5��$ � ��

5HI� /WG $VDSK 6WUHHW ID[ ��

&KULVWFKXUFK

1HZ =HDODQG

&RPPHUFLDO �� 6W� SK �� -RKQ .HOO\ 5�� WR 5��$ � 5�� WR �

5HI� $VDSK 6WUHHW ID[ �� 5��$

&KULVWFKXUFK

1HZ =HDODQG 5�� WR 6XYD� � ��

03��

$EE� 6WDO &QU SK �� *UDKDP 5�� WR ��$ � 5�� WR �

5HI� /WG 0RRUKRXVH ID[ �� *UHHQ 6XYD� +3��

$Y�

DQG /LQFROQ

5G�

&KULVWFKXUFK

1HZ =HDODQG

5�� WR �

5��

.RROLQH 5HI� �� +XWW 5G SK �� 3DXO 3DUNHV 5�� WR ��$ � 5�� WR �

1= /WG� /RZHU +XWW ID[ �� 6XYD� +3��

:HOOLQJWRQ

1HZ =HDODQG

$39 %DNHU �� 9LFWRULD 6W SK �� 1LJHO 5�� WR ��$ � 5�� WR �

1=/WG 3HWRQH ID[ �� 7XQQLFOLIIH ,VFHRQ� ��/

:HOOLQJWRQ

1HZ =HDODQG

$EE�6WDO 5HI� �� +XWW 5G SK �� )UDQN &RUU\ 5�� WR ��$ � ��

/WG 3HWRQH ID[ ��

:HOOLQJWRQ

1HZ =HDODQG

Documents

SUCCESSFUL CONVERSION TO NON-ODS REFRIGERATION