Hydrocarbon Technology. the Use of Hydrocarbons as Foaming A

8/14/2019 Hydrocarbon Technology. the Use of Hydrocarbons as Foaming A

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HydrocarbonTechnology

The Use of Hydrocarbons

as Foaming Agents andRefrigerants in HouseholdRefrigeration

Dr. Peter BazGTZ - CFC - Phase-Out Projects

Dr. Klaus MeyersenAdvisor to GTZ - CFC -

Phase-Out Projects

Dirk LegatisHEAT / Household Energy

Appropriate Technologies

Eschborn, 1996


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BMZ Bundesministerium fr wirtschaftliche Zusammenarbeitund Entwicklung

Deutsche Gesellschaft fr Technische Zusammenarbeit

For the full or partial reproduction of anything published in this yearbookproper acknowledgement should be made to the original source. Anyopinions expressed herein are entirely those of the authors.

4. Edition 05.02.96You may download this document directly from our GTZ BBS(Phone++49-6196-797396, up to 14.400 baud), Area "GTZ" or order it [email protected] via Internet.


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Contents

1. Editorial 12. Aims of the GTZ-CFC-Phase-Out-Support 53. The Status of Hydrocarbon Technology 114. The 12 Advantages of Hydrocarbon Technology 155. Hydrocarbons as Refrigerant in Domestic Refrigerators 256. The Use of Natural Refrigerants 507. History of HC Refrigerants 698. The Development of ODP/GWP Free Appliances in Europe UsingHydrocarbon Technology 1329. Natural Fluid Based Refrigeration 15110. GTZ-Layout China Project 22311. Application Form Hydrocarbon Technology 23912. Application Form Cyclopentan Technology 25913. GTZ Hydrocarbon Technology Information Service 279

List of On-line available Files in the Hydrocarbon Technology Mailbox279Literature Database 292

14. GTZ Know-How Cooperation Partners 356dkk 358

Foron 367Henneke 377Liebherr 403Plasttechnik Greiz 407

Index 425


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GTZ Yearbook 1995 Editorial 1

1. Editorial

Since the beginning of 1994, also the start of the GTZ projects to supportthe CFC-phase out, the Hydrocarbon Technology gained further ground.We hope to have contributed to this development with our support, which isrendered by GTZ under contract of the Bundesministerium frZusammenarbeit (BMZ).

The Hydrocarbon Technology is now an acknowledged and widelysupported technology within the Multilateral Fund. Yet compared to other,already firmly established CFC-substitutes, hydrocarbons need still furtherpublic support, especially in their function as refrigerants: there are still large

information gaps, there are still many questions and there are still somedoubts about this ecologically most favourable technology.

It is our hope, that with this first technically oriented publication, the "GTZYearbook 96" we may help to dissolve as many open questions as possible.This Yearbook 96 is aimed primarily at the decision seeking person inarticle-5-countries in industry as well as in governmental organisation,dealing with the CFC-substitute topic and looking for up-to-date information.

We hope that this Yearbook may contribute towards decisions in favour ofadapting the Hydrocarbon Technology as a CFC-substitute.

GTZ is co-operating with the Multilateral Fund Secretariat, the Worldbank,the other Implementing Agencies of the Montreal Protocol, as well as withenvironmental agencies, like USEPA, and federal aid agencies, such as theSwiss Development Cooperation, to assist on the technical aspects ofHydrocarbon Technology. Our main effort is to secure the technical supportof the German industry who is most experienced in this technology.

Another important aspect of this GTZ support is the dissemination of therelevant know-how to article-5-countries. GTZ maintains e.g. an on-linedatabank on Hydrocarbon Technology, of which this Yearbook is an excerpt

so to say, since all this information published here is a fraction of theinformation available via electronic means. With this hydrocarboninformation service we hope to supplement the official technical informationand documentation of the fund through UNEP.


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GTZ Yearbook 1995 MF Status 2

Earlier this year we published a special issue of GTZs "Akzente", also onHydrocarbon Technology, which "tells the stories of the hydrocarbonpioneers", in Germany, China and India, highlighting their decisions and

experiences. This was widely distributed, further copies are available onrequest from GTZ.

We kindly ask for reactions to these publications. We particularly ask forsuggestions towards improvements for the next issue, a GTZ Yearbook 96.

Thanks in advance for your support.

Dr. Peter Baz

Dr. Klaus Meyersen

Dirk Legatis


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GTZ Yearbook 1995 Addresses 3

Contact Addresses:

Dr. Peter StrmerGTZ CFC-Phase-Out-Projects

Deutsche Gesellschaft fr Technische Zusammenarbeit GmbHDag-Hammarskjld-Weg 1-5Postfach 51 80D 65760 EschbornT 0049 -6196 - 79 3198/ F - 73 52/ Modem 73 96

Dr. Klaus Meyersen

Advisor/ Co-ordinator to GTZ CFC-Phase-Out-ProjectsCorporateProcessModerationThe Other Art to consultAugustusbogen / Kstrich 59D 55116 MainzT 0049-6131-9954-91/ F -92E-Mail 101526,[email protected]

Dirk LegatisHEAT Ltd./ Household Energy Appropriate TechnologiesLimburger Strasse 29D 61479 GlashttenT 0049 - 6174 - 96 40 77/ F - 61 209E-Mail 100102,[email protected]

All can be reached via e-mail: [email protected]


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GTZ Yearbook 1995 GTZ-Aims 5

2. Aims of the GTZ-CFC-Phase-Out-Support

Dr. Peter BazGTZ CFC-Phase-Out-Projects

Dr. Klaus MeyersenAdvisor and Co-ordinator to GTZ CFC-Phase-Out-Projects

____________________________________________________

1Focus on Hydrocarbon Technology

GTZ has chosen to promote hydrocarbon technology within the frameworkof the Multilateral Fund in the belief that this technology, which has no lobby(unlike the other, more chemically-oriented substitutes supported by largechemical companies), needs and deserves public money and support as theenvironmentally most friendly form of CFC-phase-out in the domesticrefrigeration sector.

By financially promoting the use of natural gases, and through its support forForon, a company in Eastern Germany, Greenpeace Germany in 1990 hasadopted a form of positive intervention that is rather unconventional for anenvironmental organisation. By actively promoting a new technology and co-

operating with the industry, Greenpeace has demonstrated economicforesight in its endeavours to preserve and protect the environment. Thistriggered the world-wide movement towards hydrocarbons.

Keen environmental awareness on the part of the German public hashelped to set the global politico-economic stage for implementing CFC- andFC-free solutions. Similarly, the German industry has been quick to convert,thus achieving - and signalling to the world - cutting-edge technicalcompetence marked by skilfulness, composure and also a willingness tomake this know-how available to other countries.

Consequently, a spate of new ideas and activities aimed at protecting theozone layer have emerged and now need to be interlaced with the technicaland scientific competence that has been gained in the course of conversionto produce a premier package of "hydrocarbon technology". The GTZsupport will co-operate and contribute toward that goal.


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Considering the dynamic situation in Europe, the refrigerating equipmentsector suggests itself as a suitable and important field for hydrocarbonsubstitution, one for which Germanys established hydrocarbon technology

provides an inexpensive, forward-looking alternative to CFCs and FCs.That technology, however, has not yet been transferred sufficiently toarticle-5 countries. Thus, a know-how and technology transfer program forsubstitution technologies of German origin needed to be established as partof this GTZ project and know-how was made available to China and India in94/95 to be continued on a worldwide basis for 1995/97.

2The Concrete Objectives of the GTZ-CFC Phase-Out-ProjectThe conversion of refrigerator industries in article-5-countries, seems still tobe hindered by the limited access to know-how on appropriate technical alternatives, machinery and equipment experiences with substitute refrigerants and refrigerator production financial implications of the conversion marketability of ODS free products how to find financial and technical help where to find assistance.

At the same time, it is in our opinion necessary to avoid, that: refrigerant industries select those CFC substitutes who contribute to

global warming and have less than optimal effects on the energy efficiency of

refrigerators; the dependency of developing countries on the import of refrigerants and

equipment increases.

GTZ will try to give as concrete and as direct support in these areas aspossible.The very first concrete objective of GTZs CFC project was to quicklyconvert a production line for household refrigerators at a major Chinesefactory. Then to arrange and accompany consultancy services and

conversion expertise for other interested enterprises, putting them in aposition to make well-founded decisions and to submit relevant applicationsto the Multilateral Fund of the Montreal Protocol.

The first phase 1994/95 is geared to industry support. In the second phase1995/97 GTZ objectives will likely also address the repair sector. It probablywould be very worthwhile to help refrigerator repair companies convert their


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service package. Since a lot of experience is accumulating in Germany inthe meantime, we will look for leading repair enterprises as models,hopefully using their demonstration and, hence, multiplier functions and

correspondingly broad potential impact. Preparations for that kind ofassistance could be made this year in the form of, say, market audits andstructural analyses.

3Direct Concrete Bilateral Support Based on Practical ExperienceAccording to the MP, Germany - like all donor countries - may spend up to20% of its donation on direct bilateral projects between Article-5 countriesand Germany. These projects, however, must follow the rules of the MFexactly and must be approved by the Executive Committee of theMultilateral Fund. They offer the chance of very direct, fast and cost-

effective support which, we believe, is all very helpful in protecting theozone layer. With the development of this promising hydrocarbontechnology in Germany, the German government wants to take theadditional responsibility of introducing this technology where it is yetunknown - hopefully with the support of all available German resources.

The most essential principle of the GTZ phase-out support is, that thisassistance and guidance is given only through experienced personnel whohas personally experienced the process of factory conversion toHydrocarbon Technology.Since the beginning of 1994, Germany has been pursuing this possibilitythrough two GTZ model projects, one in China in close cooperation with theUS Environmental Protection Agency (USEPA) and one in India incooperation with the Swiss Development Cooperation (SDC).

The China ProjectThe China Project, the conversion of one factory line of Haier Qingdao wasa straightforward industry-to-industry supported project, with Liebherr/Germany acting as the general contractor; this project was done incooperation with USEPA. The Executive Committee of the Multilateral Fundapproved this project in March 95; the cyclopentan foaming was going inproduction in summer 95; the isobutan refrigerant part, which is funded byUS bilateral funds, will follow in fall 95. The project is labelled as ademonstration project by the secretariat of the Multilateral Fund.

The Indian ProjectThe Indian Project will have an interim test phase, during which two of thefour leading Indian companies will examine the implications of their decision


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for a given refrigerant. This is extremely important for them - as it is for allother companies in a similar situation - since these companies have theirown compressor manufacturing. Therefore to them choosing the refrigerant

is a much bigger and much more far-reaching management decision, sincechoosing 134a definitely means starting from scratch with a newcompressor design, whereas with hydrocarbon blends or even isobutanthere is a good chance that the already existing parts and modules of theold CFC-line of compressors can be used. With Swiss and German support,two Indian companies will construct cyclopentan pilot plants, since they areconfident of this aspect of hydrocarbon technology. The aim is to use theresulting cyclopentan-foamed prototypes to test and optimise - with the helpof German industrial partners - three refrigerant alternatives: isobutan,blends of propane/ butane and 134a. These efforts will be supported withinthe framework of a large nation-wide Indian project on hydrocarbon

technology involving the Ministries of the Environment and the Departmentof Explosives, official institutions such as the Indian Institute of Technology(IIT) and the National Chemical Laboratories (NCL) to procure all relevantfacts on hydrocarbon technology under "article-5-country" conditions. Thefindings will be made available to Indian industry in due course. And it is thehope of SDC and GTZ that this Indian project will have numerous andpositive ramifications in many article-5 countries.

Support to be continued 96/97With the recognition and success of these two projects in China and India,the German Federal Ministry for Economic Cooperation and Development(BMZ) is considering starting another 2-year project this fall 95 - again on alimited financial basis - to extend support for this type of technicalhydrocarbon technology also to other article-5 countries during the earlyplanning stages as well as in the implementation phase.

4On-Line Information Service on Hydrocarbon TechnologyIn addition to these projects, actively pursued in the field, GTZ hasestablished a small on-line information service, which will be furthersupplemented and constantly up-dated as long as there is a demand for it.This information service will try to give prompt answers to all relevantquestions that may arise concerning hydrocarbon technology. Anyone mayfile a request; the information given will be public domain; and no copyrightsare involved but the pledge to quote the sources when published further. Atpresent this service can be accessed in two ways: through direct modemsupport by dialling the GTZ-CFC-Phase-Out-Project in Eschborn/ Frankfurt/Germany via (49)-6196-79-7396 or by Internet E-mail via GTZ-GATE-


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3. The Status of Hydrocarbon Technology

Dr. Klaus MeyersenAdvisor and Co-ordinator to GTZ CFC-Phase-Out-Projects____________________________________________________________

1Thesituation vis--vis hydrocarbon technology in the Multilateral Fund andby the Executive Committee:

Acceptance Now for Both: Cyclopentan and IsobutanGTZ / Germany and USEPA / USA have initiated the very first "full

hydrocarbon project," with cyclopentan foaming and (!) isobutan as therefrigerant, in a bilateral project approved by the Executive Committee ofthe Multilateral Fund in the March 1995 meeting. It had been given thestatus of a "demonstration project" by the Multilateral Fund Secretariat. Withthis acceptance of the isobutan refrigerant (cyclopentan for foaming wasalready approved in the middle of 1994 and is now in fact the "worldtechnical standard"), hydrocarbon technology has now been accepted in fullby the MF and the World Bank, UNDP, UNIDO, UNEP as implementingagencies.

In this March 95 meeting the ExCom adopted for the first time a method of

setting priorities for projects to cope with the fact that there were at this timetwice as many project requests as money available to the MF.

In working out the method of setting priorities the ExCom "recognised that insome domestic refrigeration projects using hydrocarbon technologies thereare significant costs related to the provision of safety equipment and agreedthat in calculating the cost-effectiveness of such projects, the safety-relatedcosts should be identified and deducted from the total cost before the cost-effectiveness calculations are made. These costs would, however, beconsidered in determining the level of project costs and funding."(exactwording; UNEP/OlL.Pro/ExCom/16/20/ page 8)

This made hydrocarbon technology a preferred technology in a sense, sincein future it will allow the extra cost involved for the safety - due to itsflammability - of this otherwise environmentally most favourable technology,to be deducted from the incremental cost calculation when compared withother technologies (and then added to the project costs for funding when


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the project is approved; the Juliy ExCom-Meeting is said to have limitedthese safety costs to 35%).

Thanks to close cooperation with the US in this joint project, these decisionsaccomplished the GTZ objective of bringing to this new technology full MFattention and approval.

2The consequences for projects already approved in earlier meetings:

A Later Switch to Isobutan is PossibleAs a consequence of these decisions, there is now an opportunity for acountry or a company to change to isobutan / cyclopentan without going

back to the MF for approval if there are projects already approved - but notyet implemented - on "non-isobutan" and/ or "non-cyclopentan" technology.This is valid provided that the project stays within the approved incrementalcosts and that a corporate "partner" experienced in factory conversion tohydrocarbons is found and can act as advisor and supervisor in projectexecution.

GTZ provides this as standard support in their own bilateral projects, rightdown to the "approval stamp" of the German TV (the German FederalAgency for Safe Technology) which can certify safety in Article-5 countriesaccording to German safety standards.

GTZ is at present arranging close cooperation with the World Bank andother implementing agencies to further support all projects in which such aswitch to hydrocarbons is requested by a country / company. Worldbankrequires only "notification" of an intended switch.

We believe that allowing this switch to hydrocarbon technology is indeedvery important, since otherwise responsible countries with the goodintention of an early CFC phase-out would be excluded from using state-of-the-art technology.

In my opinion the MF ExCom may even have to go a step further since this"late switch" will soon be common practice: I have heard of a number ofintended project changes world-wide. The MF may then have to allow theextra costs of safety to be added to projects already approved, as they nowdo for new projects. A test case is needed for consideration and approval bythe ExCom, and GTZ is willing to support such a case. One of our


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GTZ Yearbook 1995 12 Advantages 15

4. The 12 Advantages of Hydrocarbon Technology

Opportunities for Article-5-CountriesApproved by the Multilateral FundDeveloped in GermanySupported by GTZ

A Personal Opinion

Dr. Klaus MeyersenAdvisor and Co-ordinator to GTZ CFC-Phase-Out-projects

____________________________________________________________

Monday, February 5th. 1996

PrefaceMy considerations deal mainly with the use of hydrocarbons as refrigerants(isobutane, blends of propane/butane), since I experience that thisapplication of hydrocarbons rises most of the questions. Cyclopentan as thefoaming agent I see already firmly established as the world-standardfoaming agent for the insulation of household appliances. It will thereforeonly be mentioned in passing.

I would like to point out that the aspects of hydrocarbon technologypresented here and the views expressed on this technology vis--vis theMultilateral Fund of the Montreal-real Protocol are my personal opinion.Since I am frequently asked about various aspects of hydrocarbontechnology and the present situation within the Multilateral Fund of theMontreal Protocol, I thought it might be useful to put my knowledge inwriting, and thus to take advantage of my contacts on various levels of theMontreal "scene" to pass on this information. I express my view primarily asadvisor to the Federal German Agency for Technical Cooperation (GTZ),which promotes hydrocarbon technology, but I also try to convey myobservations from and to many MF meetings and committees - such as the

Executive Committee, the OORG etc. - dealing with this technology.On one hand, the introduction of hydrocarbon technology in the domesticrefrigeration industry has gained astonishing momentum in recent months.On the other hand, large political and administrative bodies, such as theMontreal Protocol, are so slow in facilitating information flow to the"executive level" (by which I mean the level of the people actually using it!).


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So I hope - by using my semi-official contacts - to help accelerate theinformation flow within the wider scope of the Multilateral Fund and GEF upto the speed at which this new technology is gaining ground, so that the

"executive level" in article-5-countries and other countries which would liketo convert, has a chance to be informed quickly and thus to consider thistechnology as early as possible. - - - - - - -

My opinion

The HydrocarbonTechnology offersadvantageson all three levels,the global level,

the national level,the enterprise level.

1The most important aspect in introducing this technology is on the globallevel:

No Further Contribution to Global Warming

The starting point 1990 for the unbelievably rapid development of thistechnology in Germany and Europe was Greenpeaces position that onlythe environmentally most friendly technology - hydrocarbons - should beused, since 134a still has a factor 1200 over the carbon dioxide standard.So it may indeed only be a minor contribution to global warming in total,compared to other carbondioxide emission sources, it stays a signal for abetter ecological solution that became available with the hydrocarbons.

Unfortunately the Montreal Protocol is bound to support the ozoneprotection only in a narrow sense, hence will not pay for the additionalpositive effect this technology has on global warming. However, thisadvantage is well recognised by all bodies, the Multilateral Fund as well asthe Implementing Agencies and is getting their support. Although theregulations do not allow extra payment, in a way this global warmingcontribution is acknowledged in exchange for the extra costs on safety in sofar, as the costs for safety are not taken into account when compared toother technologies, but will be paid for to a certain degree.


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2The most promising facts about hydrocarbon technology however are on

the enterprise level:

The Technical Advantages will be the (!) Driving Force

There are likely more than 5 million refrigerators already produced inGermany, Europe and now also in China, without any reported accidentduring daily use. Although it was the ecological advantages that gothydrocarbons off the ground in the first place, today it is clearly the otheradvantages in regard to production and daily use which are emerging andare seen clearly now. These are hard economic facts that will interest theindustry. I am convinced that these facts will be the future driving force for

hydrocarbon technology world-wide. Facts like energy-saving, "whispering"refrigerators, readily available materials, savings in compressor design,virtually no refrigerant losses in production, extraordinary reliability of thecooling system, no fees on licences and patents, as well as the assurancethat no second conversion will be charged on the enterprises in later years,these facts will interest any manufacturer world-wide. And that will keep thistechnology moving on.

3Not fully addressed yet is the advantage on the national level:

The National Advantage of Know-How Independence

In the past this technology started with the ecological merits (Greenpeace;no global warming) which convinced the greens everywhere. Last year theeconomical advantages became obvious, which will eventually impress theindustry everywhere in the world. However this technology needs a furtherpush now. The most political argument I find still missing so far in world-wide argumentation, in particular with all the queries going on about know-how supply: the Hydrocarbon Technology leads to independence fromWestern / Northern know-how (no patents, no licenses)! This is an issue foreach company but also for the highest political level in each country, inparticular in China, India, and this will also apply to Russia and other statesbeing supported by the GEF. Governments seem to have for too longallowed themselves to stay "neutral" in the economically based strive for"chemistry base technologies". However, these technologies, hydrocarbonand ammonia, support all governments and companies in their attempts to


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lessen dependence. This technology offers the chance to adapt national"natural" solutions. Instead of being fixed to this little financial support theMF can render, instead of arguing at length about the money getting more

scarce and about the ever-changing rules and regulations which aretherefore are getting tighter, just go ahead and do it! In this public moneygame everybody seems to make fools of himself in the long run. Theselarge article-5-countries do have the means, should and could (!) easily pulltheir policy, people and other resources together and do it! By now it isproven to be simple, everybody can do it. The ever-ongoing attempts by theNorth to keep control and make profits are perfectly matched in thispsychology game by the other side due to lack of political awareness anddetermination in up-to-now know-how "dependent" countries. This to melooks like an "old" attitude, a basic reluctance to really take on responsibilityfor ones own problems. After all, everybody (!) is using the comfort of

cooling, increasingly so after 1987, the year of the MP! So, to me it seemstime has come for all of us to grow out of this behaviour of the past and startwith new thinking. Germany and Switzerland, I am certain, would be willingto assist further in any move for self-help.

4.The 12 Advantages in detail as I see them today (there may be manymore!):

Advantage 1No ozone-DepletionNo ozone-depleting effect is the prerequisite of all other cfc-substitutes

Advantage 2No Global WarmingNo global-warming effect was the starting point of the whole hydrocarbonmovement

Advantage 3No Second ConversionNo second conversion - such as the one hanging over all halogencompounds (e.g. 134a) - in the long run. 134a still contains halogens;fluorine instead of chlorine. The use of fluorine gives me, as a chemist, amore than uneasy feeling, since it is one of the most reactive of all elementsand forms the strongest acid known. Even if all living scientists were toswear that it doesnt harm the atmosphere, I would feel better if we do not


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shoot it up there. After all, yesterdays solutions often seem to create todaysproblems - as did CFCs.

Advantage 4Energy savingThere is an energy-saving effect with an optimised refrigeration system ofup to 10% over CRCs and 134a. This means a further life-long contributionnot to accelerate global warming - already a serious selling point in Europewith the newly introduced, compulsory energy labelling.

Advantage 5Quiet RefrigeratorsThe physical properties of isobutane hydrocarbon refrigerators make for

quiet, "whispering" refrigerators - an additional marketing aspect in Europe.

Advantage 6Hydrocarbons readily availableThe hydrocarbons cyclopentane and isobutane will probably (contrary toe.g. 134a) be readily available in most "Article-5 countries" and other self-relying countries as soon as there is a certain market for them, since theyinvolve no synthetic chemistry, just purification. A realistic approach onpurity demands (presently 98% pure; 99% was sought a year ago; future??%) will further ease the situation.

Advantage 7New Compressors self-madeFor companies with their own line of compressor manufacturing, thistechnology offers at least a possibility - and in most cases it is a real chance- to develop new compressors for isobutane or a propane/butane-mixture ontheir own, at relatively low cost, out of their old CFC-compressor modules,whereas 134a definitely requires a completely new design. With conversionto hydrocarbon there is in some cases a slight gain, in most cases equallevel in energy consumption compared to CFC.

Advantage 8Extraordinary ReliabilityThe most convincing argument, however, is the reliability of this system,which is bound to have fewer compressor failures. The close chemicalconnection between isobutane and mineral oil, which are both hydro-


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carbons, means that there is no interfering chemical interaction, which in thecase of CFC- and FC-compounds leads sooner or later to corrosion andhence to compressor failure, mostly due to moisture from high humidity. But

hydrocarbon compressors run "forever": test runs show that 4 million hourscan be conservatively expected (80,000 hours - 15 years - is the currentdesired standard and the average lifetime of refrigerators so far). This highreliability feature was probably the main reason why German industry,impatient with the problems caused by hydroscopic 134a-oils, convertedtwice within two years despite the double costs of conversion. Thissensitivity towards humidity is, of course, greatly increased in the tropical orsubtropical climates of most "Article-5 countries". This is why Germanmanufacturers publicly expressed to the MF their concern that in thesecountries 134a will result in a high failure rate and recommendedhydrocarbon technology for any company with a technical basis for

conversion to hydrocarbons.

Advantage 9Virtually no refrigerant lossesThe only disadvantage of hydrocarbons is their flammability, which requirescareful design and thorough employee and service sector training. TheEuropean refrigerator industry shows that it can be done.After all, the world has learned to live with a similar open system with gasescaping freely: the cigarette lighter. No one worries about people carryingthree cigarette lighters - the flammability potential of a householdhydrocarbon refrigerator - in pockets or handbags, where they bounce

around a lot more than a kitchen fridge does!Ironically I have the suspicion, that this only disadvantage is at the sametime a further advantage. Looking at the ODS phase-out effects ofhydrocarbons may result a considerable and additional contribution, al-though it is one of the hidden effects, more in the grey area of a guiltyconscience, not openly spoken about since it is embarrassing, none I couldfind in any official document yet: Due to the danger of flammability thesesubstances are naturally handled with utmost care. This has the effect thatthere is virtually no "losses" in the manufacturing process. On the otherhand manufacturers handling CFCs as well as 134a experienceconsiderable losses in these technological processes; I am told thatsometimes the amount purchased is 1.8 times bigger than that which finallyleaves the factories in form of the manufactured goods, the rest - another80%! -goes somewhere, likely due to the attitude, "it is harmless to me".This leads to the remark of one of the leading German manufacturers, that"the Hydrocarbon Technology forces us to work with this care we shouldalways have worked with".


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Advantage 10No extra Servicing EquipmentThe tenth advantage for using isobutane lays in the service sector and is

another economical benefit: There is no extra servicing equipmentnecessary for isobutane over CFC, whereas 134a requires a complete newsystem additionally.

Further on servicing:Although in this paper I am dealing only with the industrial sector I should atleast mention the service sector, since servicing hydrocarbons arises a lot ofworries against this technology. Handling hydrocarbons in the service fieldcan be as safe as CFC or 134a as far as the danger of accidents due to theflammability is concerned, the situation in Germany proves this.The use of hydrocarbons in the servicing sector offers another considerable

contribution to ozone protection, if one considers that in many countries,particularly in low CFC-consuming countries, the by far larger amounts ofCFC are used in the service sector and those will be saved.The usage of isobutane and/or blends as the refrigerant may by the wayopen a whole bundle of benefits in the service sector, e.g. due to therequired care in handling, for example using ready filled cartridges may inthe end make not only servicing safer, but less costly.Dealing with the service sector will be part of the GTZ projects 1996/97,since in particular in the area of retrofitting substantial amounts of CFCcould be phased out the quiet way.

Advantage 11Technically simple to adoptThis Hydrocarbon Technology is relatively simple to adopt by comparison to"Chemicals". As already mentioned, e.g. same oils, same compressor typeany factory is used to means less strain and stress on management andwork floor. This offers a whole range of tailor-made adaptations of thistechnology into the real existing situation, which is different in each factory.So, generally spoken, here is a chance for each in-house engineeringdepartment to come up with their "own" solution!

Advantage 12No Patents,No Licenses,No DependenceWhat was said about the independence this technology offers at thenational level, applies, of course, to the company level as well. Here is thechance for any company taking the lead in setting up their own technical


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development, taking the lead in the market, taking the chance to setengineering consultancy for other countries as soon as have been throughthe process themselves. A good and convincing example is Haier Qingdao,

after conversion of one of their factory lines now offers co-operation in theintroduction of Hydrocarbon Technology to any Indian company. In turnIndian industry may offer this to rest of the world in about one years time.

5The Outlook:

The Hydrocarbon Domino is Running

It is the conviction of people working actively in hydrocarbon projects thatthis technology needs another good push - now. But soon market forces willkeep it running! And that is the best that can be hoped for any ecologically-well-based technology. My plea to you is: Help to keep the hydrocarbondomino running in the right direction! Thanks.


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GTZ Yearbook 1995 Hydrocarbon Refrigerants 25

5. Hydrocarbons as Refrigerant in Domestic

Refrigerators

FORON HAUSGERTE GmbHEberhard GntherArnsfelder Strasse 4D-09518 Niederschmiedeberg

(Reprint from IIR Conference 1994 Proceedings"New Applications of Natural Working Fluidsin Refrigeration and Air Conditioning"May 10 - 13, 1994 Hanover, Germany)International Institute of Refrigeration177, Boulevard Malesherbes, F-75017 Paris (France)___________________________________________________________

1. PrefaceAfter having detected the detrimental influence of chlorinated fluorocarbons(CFC) to ozone layer, a goal-directed search for substitutes to be used incold-vapour refrigerating process has begun. However, alternativerefrigerating techniques have also got ever increasing importance. Althoughhousehold refrigerators contain only a small quantity of CFC in therefrigerating circuit, they became a topic in substitute investigations veryearly. This can be attributed, on one hand, to the widespread application -more than 60 million refrigerators are being produced per year on world-wide scale - and, on the other hand, to the fact that a refrigerator isconsidered an absolute necessity by many people thus being distinguishedby high acceptance.The idea that production of household refrigerators in countries aboundingin population such as e.g. India and China is steadily increasing and analternative to CFC has to be provided there very early also plays animportant role in this respect.


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2. Ozone Layer and Greenhouse EffectThe starting point of discussion on substituting CFC was first theconservation of the ozone layer of earth. This target is also in full

compliance with the stipulations laid down in Montreal Protocol.In the past, the knowledge consolidated to an ever increasing extent that thereduction of greenhouse effect has an equal importance. To promote thisrecognition process, organisations for environmental protection e.g.Greenpeace have made big efforts.Consequently, solutions have to be found upon selection of refrigerants thatwill prevent any depletion of ozone layer (ODP = 0) and, in addition, will notcontribute directly (GWP = 0) or only indirectly to a minimum extent to globalwarming.

3. Techniques for RefrigerationMore than 60 million household refrigerators annually produced world-widefunction according to the cold-vapour refrigerating process except 1 millionabsorbers.

In 1990, an assessment was made for Germany that the share ofhouseholds in energy consumption comes up to 25 %, among this, 8.2 %for coolers and 8.4 % for freezers.Thus, a market share of 4.15 % is obtained for both categories that shouldnot be underestimated, see figure 1.

Due to intensive development work, the energy consumption of householdrefrigerators could be halved in the period from 1975 till 1990. In the year2000, the same assessment will be made for the period from 1990 till 2000(figure 2000).

Thus, it becomes evident that the cold-vapour refrigerating technique haspassed an intensive process of accommodation. A considerable share inthis development is held by the hermetic compressor as proved by figure 3.Notwithstanding this positive tendency of development, this correspondsonly to a value of 39 % regarding the CARNOT process and to about 53 %of the efficiency of virtual comparative process upon isentropiccompression. As regards energy utilisation, producers of refrigerators andpower stations seem to be in a similar situation.A comparison of cold-vapour refrigerating installation to other refrigeratingprocesses such as absorbers, STIRLING or PELTIER processes and theabsorption process with ZEOLITH water as shown in figure 4 also illustratesthe actual energetic superiority of cold-vapour process. The energy yields


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known in applying these processes are between 12% and 31% of CARNOTprocess.

4. Selection of RefrigerantsThe question applied in this subtitle means: What was the reason forFORON to leave the internationally traced way to apply the refrigerant R134a as substitute for R 12 and to stake on hydrocarbons in 1992? Theanswer has two aspects.First of all, our company, as former East German monopolist, was in adesolate economic situation due to the reunification. Therefore, it was easierfor us, as compared to our competitors, to absorb ideas coming fromoutside i.e. from Greenpeace and the Dortmund Institute of Hygiene and touse hydrocarbons as refrigerant. As outlined by Prof. Kruse at a hearing

session in the German Bundestag, hydrocarbons were simply forgottenwhen searching for substitutes.Another reason to be stated here quite frankly was that FORON made useof the better technological solution implying hydrocarbons as refrigerant tostand out against the market as confirmed later on. The decisive criterion,however, was the sudden confrontation with a refrigerant featuring almostno difference to R 12 regarding its thermodynamic properties although wehad already learned to accept refrigerant R 134a due to comprehensiveinvestigations.

That is to say, reason stood at the beginning.

Figure 5 shows the family tree of fluorine and chlorine derivatives ofhydrocarbons. Consequently, only pure hydrocarbons meet therequirements to prevent ozone-layer depletion and to have no direct globalwarming potential.

Upon searching for a suitable hydrocarbon, the following criteria wereagreed upon:

equal or similar specific refrigerating capacity as compared toR 12

equal or better COP for the comparative process of a virtualcold-vapourrefrigerating installation.

Figure 6 contains a juxtaposition of the coefficients of performancepertaining to the comparative process of a virtual cold-vapour refrigeratinginstallation referred to R 12 for CECOMAF-LBP test conditions and field-experienced application conditions in refrigerators. The energetic benefits of


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the mix R 600a/R 290 and R 600a in contrast to R 12 and, in particular, R134a become clearly evident.In figure 7, a comparison of specific cooling capacity is shown, again

referred to R 12.Here, the best coincidence with R 12 has been obtained for the mix ofpropane/isobutan with a ratio of 50/50. For isobutan, a considerablecorrection of working volume has to be effected. For proving thethermodynamic properties of different refrigerants, theoretical investigationswere carried out by means of provided simulation programs on hermeticrefrigerant compressors over a wide range of applications. Figure 8 shows acomparison for refrigerants R 12, R 290/R 600a and R 600a.

Here, the essential proof could be furnished that equal or even bettercoefficients of performance are achieved when using hydrocarbons as

refrigerants as compared to the refrigerants R 12 or R 134a. The differentload moments can be compensated by appropriate motor corrections.These theoretical investigations were confirmed by experiments underselected conditions. The results are summarised in figures 9, 10, 11 and 12.

The following can be derived from considerations made with regard torefrigerant selection:

The existing compressor design versions are generally appropriate forhydrocarbons.

Upon exact motor allocation, energetic improvements can be achieved in

contrast to R 12 and R 134a. An R 12 substitute with hydrocarbon as single-fluid refrigerant does not

exist. The double-fluid refrigerant R 290/R 600a with 50 per cent by weight

each corresponds approximately to R 12 as regards its cooling capacity. For achieving equal cooling capacity as to R 12 and the use of isobutan,

corrections of working volume will be required.

The possible application of mineral oils has turned out to be a benefit forhydrocarbons, however, with a higher viscosity class than R 12 since thereis a very intensive solubility of refrigerant in oil considerably decreasingviscosity.


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Another benefit implies the essential thermal relief of compressor shown infigures 11 and 12. This instance has advantageous influences on servicelife, particularly under high ambient temperatures as found in many

emergent countries.Even for other applications e.g. heat pump, this thermal benefit is utilisedwhen using hydrocarbons, in particular, for elevating the condensationtemperature.

5. Energetic Efficiency of RefrigeratorsThe better energetic properties of refrigerant mix R 290/R 600a proven oncompressor shall be transferred to the refrigerator and shall bring about anequally good energetic behaviour there.Whereas no modifications on refrigerating installation were required

between R 12 and R 134a (except compressor), slight detail changes had tobe implemented in the cooling circuit when using R 290/R 600a. This refersparticularly to evaporator and capillary tube.Figure 13 shows selected refrigerators using R 12 and hydrocarbons asrefrigerant.Energy consumption of refrigerators was reduced up to 19%, in somecases, an equal value as compared to R 12 could be reached "only".After FORON started manufacture of first refrigerators with refrigerants onworld-wide scale on March 15, 1993 a lot of experience could be acquiredleading to the fact that pure isobutan has been applied as refrigerant in ourcompany since March 1994.


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Two reasons can be identified for this:

The vapour-pressure curve included in figure 14 clearly shows the smaller

mechanical load for refrigerant R 600a. This will bring about considerableacoustic benefits with equal energetic behaviour. This benefit, however, hasto be purchased by comprehensive modifications to be made oncompressor. The required working volume for a definite cooling capacity isapproximately double as high as shown in figure 4.

Due to the tendency towards essential improvement of heat insulation,compressors with ever smaller cooling capacities are required for newseries of household refrigerators built. Thus, working volumes smaller than2 cm are prevailing for the refrigerant mix R 290/R 600a which can only beimplemented hardly. Necessary doubling of working volume for isobutan is

the appropriate way out here.

The trend towards isobutan, however, may also result in a revival of theintensive discussion held in Europe in the middle of the eighties about theapplication of rotating piston compressors in household refrigerators.Essential disadvantages such as internal leakproofness and coolingcapacity limit at 100 W are influenced to a considerable extent.

6. Demands made on Technical SafetyHydrocarbons figure among the group of flammable refrigerants. Use ofsuch refrigerants in household refrigerators calls for clear answers toquestions regarding safety during manufacture, transportation, purposefulapplication and servicing of such appliances. Such questions have to beanswered very carefully because an entire branch was upset by them.Since there were no clearly defined stipulations during development ofrefrigerators, maximum safety demands were elaborated. In such technicalsafety regulations as e.g. DIN EN 2711, the statement is made fortransporting and storing flammable or caustic fluids and gases that single-shell metallic compounds such as pipes, bins etc. perfectly joined with eachother by welding, soldering or other equivalent techniques are technicallyleakproof.Irrespectively of the mass of hazardous substances, there is no danger areaoutside these components. This could have been applied for refrigeratorswith hermetically tight cooling circuit (state of the art of gas engineering).The safety concept made out together with Bavarian and SaxonEngineering Control Associations and taken as a basis in the FORONcompany, however, starts from the fact that leakages might be possible.


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The following requirements were consequently derived:

Fundamental requirement

The appliances have to be designed so that fire and explosion hazards dueto refrigerant mix with air even as consequence of unfit or carelessmanipulations are prevented as far as this can be implemented.

Demands made on appliance design.

The components of refrigerant circuit have to be designed, arranged andfastened so that protection against leakages due to mechanicaldamages even due to unfit or careless manipulations is ensured as faras possible.

Refrigerant-carrying components should not be used as spacers whenerecting the appliances.

Dead spaces in the outside area of appliance shall be avoided upondesigning the appliance.

Protective covers for electric equipment (e.g. thermostat and light push-button) serving for stabilisation of permitted refrigerant-air concentrationparameters have to be designed and fastened so that they can bedislocated only by means of tools. Protection against accidental contactand/or water can also be ensured by means of these protective covers.

Demands made on electric equipment Interior of appliance:Electric equipment (possible ignition sources) should not be arranged in theinterior of appliance. Such equipment should also not be introduced in theinterior.Exception:

The electric devices are conceived for use in potentially explosive areas ofzone 2 as per DIN VDE 0165.

Minimum demand regarding type of protection: IP 54.

Exterior of applianceElectric equipment can be installed in the exterior of appliance after havingproved that a refrigerant concentration of 0.5 lower explosion limit is notexceeded in immediate vicinity of their switching contacts upon leakages inthe cooling system.

Demands made on leakproofness of cooling system


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Particular attention is paid to the implementation of demand for ensuringleakproofness in cooling system. The following conditions have to bechecked:

constructive prerequisites (minimising nondetachable joints in coolingsystem)

technological prerequisites e.g. testing techniques including severalforced routine tests regarding leakproofness by means of highly sensitivetesting equipment

Check observation of maximum working pressures permitteddetermination of dead overpressure in the chiller at an ambienttemperature of 63C

determination of working overpressure in the appliance (suction andpressure sides) when approaching an ambient temperature

For practical implementation of this concept as well as for meeting alldemands made by Engineering Control Association (TV) or TradeSupervisory Authority for safety of appliances and manufacture, thefollowing essential modifications had to be made in contrast to R 12manufacture:

separate strength test of high-pressure and low-pressure sides ofrefrigerating installationlocation of evacuating and charging devices in a separate compartment.

For improving and permanently checking the quality of manufacture, a newcharging unit to be applied optionally for hydrocarbon mix and individualcomponents with a charging accuracy of < 1 g was installed additionallydetermining the degree of evacuation prior to the charging procedure.The results of strength test, final leakproofness inspection and electric testare recorded and acquired by computer.This sequence ensures maximum safety and excellent quality of products.

7. Servicing Household Refrigerators using Hydrocarbons asRefrigerantConstruction and mode of function of chillers comply with those ofconventional design versions using CFC refrigerants including the followingmain components: compressor, evaporator, condenser and capillary tube.All these sub-assemblies have been matched with the specific parametersof refrigerant and with the particular appliance.


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Error diagnosis is as compared to appliances using CFC refrigerants. Thismeans for the service man to proceed as carefully as hitherto known duringrepairs on sub-assemblies of refrigerant circuit.

A filter drier is installed between condenser and restrictor in order to ensurecleanliness and dryness. Constructive design, drier medium and capacityare identical with the parameters pertaining to refrigerant R 12.The charged refrigerant quantity required for the operation of chiller isreduced approximately by factor 3 due to the physical properties ofhydrocarbons and due to the measures taken for the decrease of chargedquantity i.e. the quantities of this refrigerant to be charged for householdrefrigerators will amount to about 10 - 50 g.

Since refrigerants of group 3 are concerned as per European standards,recharge of repaired chillers with volumetric feed via visual inspection

through inspection glasses cannot be applied; quite a usual procedure for R12.

Due to the application of an exactly metered recharge cartridge, thisprocedure can be eased considerably and carried out without any faults.Since there are no chemical contact reactions between R 12 andhydrocarbons, the service equipment can be used for refrigerantR 12.The simpler solution implies accomplishment of charging procedureapplying usual refrigerant filler hoses in connection with a vacuum pump,servicing aid and recharge cartridge. This is shown in figure 15. This

procedure brings a weight decrease of more than 50% as to equipment forthe service man and a cost reduction of more than 60% when purchasingthe equipment together with the benefit of volume reduction in the servicevan for equipment to be transported.Instead of this conventional solution, the charging station usually applied forrefrigerant R 12 can also be used without any problems. An additionalconnection only has to be retrofitted on the pressure gauge assembly forby-passing the charging cylinder (figure 16).Here, the same service equipment for technical servicing can be used forappliances with refrigerant R 12 as well as with hydrocarbons.Application of hydrocarbons will not require any peculiarities for thenecessary joining procedures upon replacement of the components ofrefrigerant circuit. Such usual techniques as brazing or press fitting (lockring) have stood their test in practice.Refrigerant recharge cartridges are made available by FORON as spareparts.


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8. Remarks concerning Situation in Emergent CountriesUpon selecting hydrocarbons as refrigerant, we also tried to take the

situation in emergent countries into account. According to our opinion, it isnot possible to apply new technologies exclusively in the advancedindustrial countries.Due to the physical properties of hydrocarbons, compressors andappliances can be produced according to the manufacturing techniquesknown for R 12 by means of the installations provided for R 12.Thus, the possibility will exist to apply the technique developed by FORONon a world-wide scale for the sake of environment.The refrigerant changeover can be implemented in already existing plantswithout profound modifications and without high capital expenditure. Thisrefers to the changeover of PUR foam systems to the blowing agent

cyclopentan, too. The results obtained in our company during changeover ofequipment (figure 13) can also be achieved there. This statement is alsoproved by the experience acquired by European and Asian manufacturersduring the changeover of refrigerators to hydrocarbons. The energeticimprovements thus obtained are frequently much more higher wheneffecting further accommodation of cooling installation.It should also be stressed here that the safety concepts elaborated togetherwith the Engineering Control Association are applied in respectivelymatched form.

9. Conclusion

The statements made in this paper shall furnish proof of the fact thathydrocarbons are not only a substitute for CFC and HFC in the branch ofhousehold refrigerators but also represent an excellent alternative for thesolution of such global problems as ozone-layer depletion and globalwarming. The possibility of continued use of already existing productionplants for compressors and household refrigerators without any profoundtechnological modifications is particularly profitable. The use ofhydrocarbons also gives a reply to the actually prevailing TEWI discussions.When using refrigerants without any direct global warming potential (GWP =0), the greenhouse effect can only be attributed to the energetic behaviourof appliances indirectly via CO

2output of power stations.

The output value in Germany is 0.55 kg CO2/kWh.

The application of hydrocarbons, maybe a mix of propane/isobutan or pureisobutan, will ensure improved energetic behaviour due to the substanceparameters. Practical implementation of this in connection with safetyconcepts for operating and producing refrigerators is an interesting


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engineering job. If disadvantages are detected upon TEWI investigations onrefrigerators with hydrocarbons, this will be a safe sign for the fact that aninteresting engineering job has not yet been completed successfully.


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i

year

CCopOP in W/W

1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000

0,55

0,7,7

0,0,,9

1,1

1,3

Trend of COP for hermeticprocessors

April 94 picture 3

condtions:

Q0 = 100 W, 220V/50 Hz,

CECOMAF-LBP, statically ventilated,

refrigerants: CFC, H-FC, HC (beginning 94)

Cop in W/W


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GTZ Yearbook 1995 Natural Refrigerants 51

of application. Among them are a number of "natural" substances like, forinstance, air, water, nitrogen, ammonia, hydrogen, helium, hydrocarbonsand carbon dioxide, which all have possible application in the refrigeration

technology of the future.

The ideal refrigeration or heat pump cycle for a given purpose is defined bythe boundary conditions of the application and completely independent ofthe refrigerant used. The concept of the Carnot process as the idealreference is only valid in the case of heat absorption and rejection atrigorously constant temperatures which can be closely approached byisobaric evaporation and condensation of a pure medium. In most practicalcases heat will be exchanged with finite flows of liquid or gas with a more orless pronounced temperature glide. For the temperature lift and drop bycompression or expansion the reversible adiabat is the natural ideal in most

cases. In the common case of air cooling, using ambient air or water as aheat sink, the reference cycle may look something like the heavy drawncircuit in the T-s-diagram, Fig. 1. In order to achieve an acceptableefficiency the real cycle should approach the theoretical ideal as closely aspractically possible. The possibilities are limited by the processes we areable to realise in the available types of equipment, compressors, expandersand heat exchangers, within economic limitations.

Rational compressors and expanders will operate near adiabatically sincethe surface area of their working space is much too small to provide anyappreciable heat exchange. Considerable exergy losses occur as a result of

internal friction and other irreversibilitys. Philips and Vuilleumier machinesdiffer in that they have advanced heat exchangers built into their activeworking volume, but even so they are far from achieving the desired near-isothermal processes. Liquid injection (or wet suction) is often proposed asa means of cooling in all types of compressors, but introduces additionallosses far in excess of the theoretical gain [4]. We are by no means able toproduce the arbitrary "polytropes", so popular in theoretical analysis.

Figure I - Example of the theoretical cycle for a common refrigerationapplication (thick lines 1-2-3-4-1) and the real cycle 1-2-3-4Heat exchangers (evaporators, condensers etc.) require a temperaturedifference for functioning, depending on the surface area which has to bedecided on economic criteria. The corresponding exergy loss is oftenincreased as a result of poor matching of the temperature curves of therefrigerant and outside transport medium. Gliding temperatures cancertainly be generated in gas cycles, by use of zeotropic mixtures or


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approached by staging, but it is rarely possible to get a perfect fit in heatabsorption and discharge at the same time.

As a result of these various difficulties the real cycle will always differ veryconsiderably from the ideal. As a typical example a normal refrigerationprocess is plotted in Fig. 1, using realistic performance data for the systemcomponents. The power consumption, excluding motor and transmissionlosses, is represented as the area 1 -c-d-2-3-a-b-4-1, and is several timeslarger than theoretically required. Correspondingly the true efficiency ofcommon refrigeration and heat pump systems is very low and often in therange 10 to 30 per cent. The possibilities for further improvement areconsiderable.

While the thermophysical properties of the refrigerant have no influence onthe theoretical cycle and affect the Evans-Perkins process (some timeserroneously referred to as "reverse Rankine") only slightly through theirinfluence on the superheat and throttling loss, their effect on the otherthermodynamic losses is considerable. Most important in order to limit theheat transfer, flow resistance and compressor losses are a low molar massand suitably high pressure at working conditions. The common halocarbonsare not particularly effective in these respects. The popular comparison ofrefrigerants on the basis of their theoretical performance in the Evans-Perkins cycle can therefore be very misleading.

After a brief reference to the status of gas cycle systems, the followingpages will discuss how a few natural refrigerants, ammonia, propane andcarbon dioxide, can be used to advantage to cover the needs of mostnormal refrigeration and heat pump applications, using conventionalcompressor systems.


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Fig. 1

2. Gas Cycle MachinesSo called "cold air machines" as first introduced by Gorrie in 1844, wereused extensively during the final decades of last century and well into thisone, mainly for marine refrigeration. They were large, steam driven,reciprocating machinery, open on the suction side for direct cooling of thecargo holds, and the air was often cooled during and after the compressionby direct water spray. The compressor cooling presumably had some effect

in the large volume slow moving machines. Even so, the powerconsumption was excessive, the equipment was very bulky and spaceconsuming, and there were troubles with icing up of the system, oil fumes inthe air etc. The cold air machines were therefore quickly replaced byammonia or carbon dioxide plants as they were developed to satisfactoryreliability.

The open cycle cold air machine or heat pump may seem very attractive byits simplicity and environmental advantage, and numerous attempts havebeen made over the years to revive the idea, eliminating some of itsdrawbacks by using turbo or other high speed rotary machinery. The

problem of excessive power consumption remains, however, Fig. 2A. Thesystem is used some times for air conditioning in military aircraft, wherecompressed air is available from the jet engine and low extra weight isconsidered more important than fuel economy. It has been proposed forspecial services like cooling of deep mines by using compressed air fromthe surface to drive pumps or other mining machinery, or for sporadic


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freezing of products, using discarded aircraft turbines. None of these ideashave found any wide application.

It is clear that the open cold air system has little chance of gaining anyimportance for refrigeration or heat pumps in the normal temperature rangeunless a significant break-through should occur. This does not seem verylikely at the present time.For lower temperatures, below say 200 K, the situation is quite different.

Fig. 2a and 2b

Open transcritical cycles with counterflow heat exchangers have been usedto condense air and other "gases" for more than 100 years, and similararrangements are applicable for space cooling. Fig. 2 B. More recently highpressure closed gas cycles have been developed, using hydrogen or heliumvery effectively (Philips etc.). At high pressures, high temperature lift, usingthermal regeneration and high heat transfer gas, the problems associatedwith the open cold air machine are greatly reduced.

3. The Refrigerant RevolutionThe first halocarbon refrigerant, R-12, was introduced in the USA in the

early thirties. 20 years later the newcompounds had conquered the greaterpart of refrigeration applications the world over, starting with the smallerequipment and air conditioning, gradually penetrating into even the largeindustrial area. Ammonia only has remained the preferred choice in thelatter field.


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One may well wonder why this revolution happened so quickly at the time,in spite of many practical difficulties in the beginning. Important factors werecertainly the heavy advertising, an effective system of technical information

and well organised effort by the manufacturers to solve the variousproblems as they occurred. But I am sure an equally powerful motive forchange was the possibility to use simple and cheap construction methods,copper tubing, light screw or solder fittings, cheap automatic controlequipment. hermetic motors etc. Small leaks did not matter much since theywould not be noticed until refill became necessary, and this was a simpleand relatively cheap operation. not without interest to the service firms andrefrigerant supplier. The work could be done by people with limitedqualifications, and we ended up with a contractor industry structure and lackof professionalism which contribute strongly to the problems we are facingtoday.

Now we have to revert to systems which must be absolutely tight and staytight over their lifetime. We have to design for safety, even though somerefrigerants may be combustible or even poisonous. We will have to rebuildthe professional and responsible attitude of former days. If we manage this,we have at our disposal a series of natural, cheap and thermodynamicallyexcellent working media.

I have no doubt that practically all normal refrigeration and heat pumpneeds in the future can be adequately served by three abundantly availablenatural refrigerants: Ammonia, Propane (or hydrocarbon mixtures) and

Carbon Dioxide. This will require a concentrated effort to recover lostdevelopment during a half century of halocarbon domination. As a result wecan expect a better and more energy effective technology, free ofenvironmental problems and the monopoly of big chemical companies.

In the following we will take a brief look at some important aspects of thecandidate refrigerants mentioned. Some characteristic data are compiled inTable I in comparison with common halocarbon alternatives:4. Ammonia, the prooven RefrigerantAfter 120 years of extensive usage a tremendous amount of practicalexperience with this refrigerant exists. There is no doubt about its excellentthermodynamic and transport properties, much superior to those of anyhalocarbon. It is a well known fact that an ammonia plant always has aconsiderably better energy efficiency in practice, when compressor speed,piping dimensions and heat transfer equipment are decided on economiccriteria. Other important advantages are tolerance to normal mineral oils,low sensitivity to small amounts of water in the system, simple leak


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detection, unlimited availability and low price. All these factors contribute toits sustained popularity and wide application.

It is true that ammonia is poisonous and can burn with air, although thesedefects have often been grossly exaggerated. In reality it is 10 to 50 timesless toxic than chlorine, for instance [5]. Its lower ignition limit is as high as15,5% by volume, 3 to 7 times that of common hydrocarbons and naturalgas, and the combustion heat less than half. Experience shows thataccidents are extremely rare, be it by poisoning or explosion. A recentinvestigation indicates that fatal cases are at least as frequent withhalocarbon refrigerants [6].

An invaluable asset of ammonia is its strong, penetrating and to mostpeople unpleasant smell. Ironically enough this may be the reason for the

exaggerated fear, while it is in reality a most valuable safety factor. The gasis easily detected at a concentration as low as 5 ppm in air, and it takes a1000 times higher content before there is any real danger. The margin ofsafety is thus extremely generous and it takes very special circumstancesfor any critical situation to occur. An analysis of known cases shows thatextreme negligence and violation of elementary safety precautions areinvariably the cause.

It is very simple in principle to build an ammonia plant to any required levelof safety. The gas is much lighter than air and easily vented away, and it ishighly soluble in water. By simply placing the ammonia containing

equipment in a closed and reasonably tight compartment or box andventilate it to a safe place over the root or a built-in water reserve, any riskof external leakage dung operation can be eliminated. The ventilation can, ifneed be, be controlled by a gas sensor Distribution ot cold to the places ofusage must. of course, be done by a safe secondary refrigerant in premisesaccessible to the public, except for very small capacities. Work on ammoniaequipment for repair or service must be carried out by qualified personnel.The need to use indirect cooling is the one considerable drawback ofammonia (and other combustible refrigerants) since most available brinesare quite viscous at low temperatures, with high pumping powerrequirement and poor heat transfer. There is presently a strongdevelopment to improve on this situation, and new brands are constantlybrought on the market [7].

The objection is often heard that an ammonia plant is more expensive thanits halocarbon equivalent, and this is certainly true if it is a special one of akind installation. But there is no reason it should be that way under equal


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conditions of production. On the contrary ammonia has a number of strongpoints which can actively reduce first cost:

The optimum compressor speed is inversely proportional to the square rootof the molar mass of the refrigerant [4]. An ammonia machine needs lessthan half the swept volume of one for R-22 with the same capacity.

- The size of piping and armatures can be reduced in the same ratio

- The heat transfer area of condenser and evaporator can be reduced as aresult of the excellent heat transfer efficiency of NH3.

These considerable savings should more than compensate for the extracost of a brine pumping system and casing.

A development on the lines described is retarded by the lack of suitablesmall ammonia compressors and control equipment in the market and thescarcity of people with practical experience of this refrigerant. In particularcost effective small hermetics are needed, although some "canned motor"type machines are already available. More suitable evaporator designs arealso required. The liquid/gas volume ratio for NH3 is very low and theproblem of correct distribution and wetting of the heat transfer surface in"dry evaporators" is correspondingly even more difficult than for thehalocarbons. Some type of flooding seems indicated.

The progress is now well under way, however, and we can expect a rapid

growth in NH3 usage in the next few years. One exception is turbomachines, where a working medium with a somewhat hither molar mass isdesirable.

5. Propane, a promising AlternativePropane and Ethylene have been used successfully as working media inlarge refrigeration plants for many years, notably in the petrochemicalprocess industry. Mixtures of hydrocarbons, adapted to the desiredtemperature glide, give excellent service in the enormous condensationtrains for natural gas. 45 years ago propane was tried in small refrigerationsystems of conventional design without any problem and with excellentperformance [4].

Propane (C3H6, R-290) has excellent thermodynamic properties, similar tothose of ammonia (or R-22 for that matter). The molar mass of 44 is idealfor turbo compressors and only about half to one third of that of its


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halocarbon competitors. Its transport properties are correspondingly better,although they do not quite match those of NH3. Propane is compatible withnormal lubricating oils and machine building materials, universally available

and low in price. Its physiological properties are comparable with those ofthe CFCs, although it has no harmful decomposition products in a fireexcept possibly CO at incomplete combustion.

The only important disadvantage of hydrocarbon refrigerants is that they arecombustible with a very low ignition concentration limit (Table I), and thisdrawback has been blown up to unreasonable proportions. As a fact theyare popular fuels available everywhere and used with simple precautionseven in private homes, caravans and small boats. With reasonably carefuldesign it must be even more simple to ensure safety in a hermetic closedrefrigeration circuit.

Inside the working system it is physically impossible to create an explosivemixture. The amount of air required would exceed by far the limits permittingof normal operation. Any risk is therefore associated with leakage to theoutside and can be eliminated by suitable enclosure and ventilation asdescribed for ammonia. Even greater care is required in repair and service,however.Propane is an obvious alternative to ammonia in ad kinds of refrigerationand heat pump application. Direct cooling is possible in small systems,when the charge is low enough to avoid any explosion risk in rooms whereleakage may occur. One advantage is that the hardware can be very similar

to CFC practice and familiar to service personnel. Propane can of course bemixed with other hydrocarbons to adjust the pressure and generate glidingtemperatures.

After years of hesitation hydrocarbon refrigerant is beginning to findapplication in household equipment. A 50/50 mixture of propane andisobutan (R-290/R-600a) is used to approach the pressure and capacitycharacteristics of R-12 [8]. It is hard to see that the small charge of typicallyless than 50 g can represent any danger, and extensive analysis andpractical testing in the USA and Germany have confirmed its safety. Also,millions of Platen/Munters refrigerators, charged with ammonia andhydrogen (!), have been used over the years without any accidents exceptan occasional "bad smell".It is hard to see why hydrocarbons cannot provide a solution for other smallequipment as well.


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In large systems using turbo machinery propane has a particular advantagein that its molar mass is near the ideal to achieve the optimal Mach numberwith an impeller tip speed adjusted to the strength capabilities of modern

materials and design. This favours a compact design with a minimumnumber of stages.

6. Carbon Dioxide, the unique RefrigerantCarbon dioxide was a commonly used refrigerant from the late 1800s andwell into our century. Due to its complete harmlessness it was the generallypreferred choice for usage on board ships, while ammonia was morecommon in stationary applications. By the advent of the "Freons" and R-12in the first place, the use of CO2 was rapidly interrupted. The main reasonfor this development was certainly the rapid loss of capacity at high cooling

water temperatures in the tropics, and not less the failure of themanufacturers to follow modern trends in CO2 compressor design towardsmore compact and price effective high speed types. Time is now ripe for are-assessment of this refrigerant for application with present daytechnology.Disregarding air and water, CO2 is certainly the refrigerant coming closestto the ideal of harmlessness to the environment [9]. With regard to personalsafety, it is at least as good as the best of halocarbons. It is non-toxic andincombustible, of course. By release from the liquid form about half willevaporate while the remainder becomes solid in the form of snow and canbe removed with broom and dustpan, or just left to sublimate. Most peopleare already familiar with the handling of "dry ice". In the case of accidentalloss of a large quantity, a good ventilation system is required in order toeliminate any risk of suffocation, in particular in spaces below ground level.In this respect the situation is the same as for any large halocarbon plant.

It is some time maintained that the high pressure of CO2 could constitute aspecial danger in the case of accidental rupture. Actually this is not so sincethe volume is so small. In the same way as the product P*V isapproximately the same for all systems with the same capacity, the sameholds for the explosion energy, regardless of the refrigerant used.

As a fact, the high pressure and correspondingly low specific volume isperhaps the greatest advantage. The pressure level is close to the optimumfor modern machine technology, as demonstrated by fields like powerengineering, oil hydraulics and other processes, where it can be chosenfreely. The Philips machine is another example, working at about 100 bar. In


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the vicinity of the critical point heat transfer is also particularly effective. Allthis makes for a very compact and cost effective design.CO2 also has a number of further advantages:

pressure close to the economically optimal level greatly reducedcompression ratio compared to conventional refrigerants completecompatibility to normal lubricants and common machine constructionmaterials easy availability everywhere, independent of any supply monopolysimple operation and service, no "recycling" required, very low Price.

One problem of this refrigerant, and in some applications an importantasset, is its relatively low critical point of 31C. With condensation wellbelow this temperature, in a cool climate or in a low stage of a cascadesystem, it works with condensation like any other refrigerant. As the criticaltemperature is approached or even exceeded, the losses by superheat and

throttling increase. It turns out, however, that in some cases this can becompensated by much improved compressor performance as a result ofvery low pressure ratio and small volume requirement. This has been amplydemonstrated by the motorcar air conditioning system, which is fullydescribed in reference I l01.

There is no doubt that CO2 can be used with similar success in other smallrefrigeration systems as well. For larger capacities it may be worth while totake measures to reduce the losses by superheat and throttling. Oneobvious way is by staged compression and expansion, Fig3. Anothertempting solution can be to recover expansion work in using a suitableengine, since the properties of CO2 make this feasible.

With a conventional refrigerant like R-12 most of the theoretical expansionwork comes from the flash gas and the P-v diagram becomes very thin, witha low mean pressure, Fig 4. For CO2 the situation is quite different, withmost of the work in the liquid phase, a high mean pressure and smallvolume requirement. An expansion aggregate becomes a cost effectiveelement in large installations, I l ll.

In some cases the characteristics of a trans critical process are particularlywell adapted to the application, when a strongly gliding temperature of heatdischarge is desired. Most heat pumps extract low temperature heat fromthe immense reservoir of the environment (air, water, rock ...) and a processwith constant temperature evaporation is therefore quite suitable rejection atessentially cons with gliding temperature 0T.


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Such a process can be at Fig. 6. In order to get a sat absorbing medium(water), of 90-100 bar or higher. Tl 0C, the discharge temperature about70-80C. This temper the discharge pressure and a 100 mW heat pump

with identical boundary conditions for the purpose. They give off the thermalenergy at a higher temperature to a finite stream of air or water with limitedheat capacity, resulting in a more or less gliding temperature. The amountof temperature change can range from a few degrees in a small directcondensation air heater, 15-20 K for normal "split units", up to 30-40 K inlarge district heating networks and even more in some industrialapplications and direct tap water heating.

Fig. 3


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Fig. 4

This causes a very considerable excess power requirement in the normaltype of cycle with condensation and heat rejection at essentially constanttemperature, Fig 5A. What one should really have is

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Hydrocarbon Technology. the Use of Hydrocarbons as Foaming A