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Substitutes for Potent Greenhouse Gases

3 Application of HFC substances and possible alternatives

HFC (HydroFluoroCarbons) is the name for various substances, which have been produced by placing a number of fluoride atoms on hydrocarbons. However, some hydrogen atoms will be left in the molecule. The most common HFC substances are:

Substance

Chemical
Formula

Boiling
point (C)

GWP
(100 yr)

Atmospheric
life time (yr)

HFC-23

CHF3

-82.1

11700

264

HFC-32

CH2F2

-51.7

650

5.6

HFC-125

C2HF5

-48.4

2800

32.6

HFC-134a

CH2FCF3

-26.5

1300

14.6

HFC-143a

CF3CH3

-47.5

3800

48.3

HFC-152a

C2H4F2

-24.2

140

1.5

HFC-227ea

C3HF7

-17.3

2900

36.5

The indication R-134a which is commonly used, means R for Refrigerant. The indication HFA-134a, which corresponds to HFC-134a, is also used. HFC substances are often used in refrigerant mixtures, which are provided with the R- 400 or the R-500 serial number. In annex A an overview of refrigerants and refrigerant mixtures is provided.

The HFC substances are used in Denmark mainly as refrigerants in refrigerators and as blowing agent of polyurethane foam. The HFC substances are also used for a number of minor purposes, for instance as propellant agent in special aerosol cans. Abroad, HFCs are used for special fire extinguishing purposes.

This chapter is divided in sections according to main consumption areas. In section 3.1 the refrigeration industry is discussed and the chapter is further divided, e.g. for domestic refrigerators and freezers, commercial refrigerators etc.

3.1 Refrigeration industry

The refrigeration industry in Denmark is of significant importance and includes companies such as Danfoss, Sabroe, Gram, Vestfrost, Caravell, Elcold and Gramkow.

About 15,000 people are employed within the refrigeration industry, which has an annual turnover of more than 15 billion DKK. Thus, it is an industry of major importance to Danish economy and employment.

The refrigeration industry produces a large number of products covering a wide spectrum. From mass-produced refrigerators and freezers to industrial refrigeration plants, produced by Sabroe Refrigeration, one of the worlds leading manufacturers of such. In addition, various components for refrigeration plants produced by Danfoss, one of the worlds leading manufacturer of refrigeration components. Also minor refrigeration companies, assembling commercial refrigeration systems in supermarkets, could be mentioned.

This chapter is divided according to main products. Paragraph 3.1.1 describes domestic refrigerators and freezers. In this chapter both the consumption of HFC, used as refrigerant in refrigerators and the consumption of HFC as blowing agent of insulating foam in the cabinets are mentioned, as these areas of consumption are closely related.

3.1.1 Domestic refrigerators and freezers

There are 6 Danish manufacturers of refrigerators and freezers, i.e. the companies of Vestfrost, Gram, Caravell, Derby, Frigor and Elcold. Annually, these companies produce app. 1.5 million units and most of them are exported. App. 1 million units are household refrigerators and almost half a million units are commercial refrigerators.

The annual sales in Denmark of domestic refrigerators and freezers has for years ranged between 250,000 and 300,000 units, among which a significant number of refrigerators are imported from Germany, Italy and Sweden in particular.

An estimated 5.000 people are employed within the production of refrigerators, freezers and components. Obviously, this industry is very important to Danish economy and employment.


Until 1993, domestic refrigerators and freezers were produced with CFC substances in the cooling circuit and in the insulation foam. App. 100 - 200 gram of CFC-12 was used in the cooling circuit and app. 500 gram of CFC-11 was used in the insulation foam.

In the following years the refrigeration industry went through a rather turbulent period due to a number of technologies being introduced as substitutes for CFC. At first, HCFC substitutes were used in replacement of CFC-11 in the insulating foam.
Danfoss developed compressors that could use HFC-134a as refrigerant.
These technologies were introduced by Danish and foreign manufacturers of refrigerators in replacement of the CFC technology. From an environmental point of view the advantage was significant. The Danish manufacturers of refrigerators were some of the first deliverers of non-CFC refrigerators, which made them competitive on the European markets where restrictions on CFCs in refrigerators had been introduced. As a result of this, the production at Vestfrost in 1994 was more than 700,000 units.
After that time, demands also appeared to the phasing-out of HCFC substances. Some companies introduced HFC-134a as blowing agent of the insulating foam. This was additional environmental progress compared to previous methods, as the refrigerators were now completely nondependent on any form of ozone depleting substances.

The environmental organisations started to question the environmental impact of the HFC substances. Certainly, the HFCs are not depleting the
ozone layer, however they are potent greenhouse substances which will contribute to an increased greenhouse effect when released in the atmosphere. Thus, finding alternatives to the HFCs would be advantageous.

It should be mentioned that the CFC and the HCFC substances are potent greenhouse gases as well.

In 1992, Greenpeace Germany joined forces with the previous East German producer of refrigerators, FORON, and produced a refrigerator (called "Greenfreeze") operating on a refrigerant mixture of propane and butane. The mixture had pressure and temperature conditions, corresponding to CFC-12, and the system was provided with a CFC-12 compressor. The entire system worked satisfactorily. By these means Greenpeace contributed effectively in breaking down a psychological barrier against the use of a flammable refrigerant.

Danfoss started up development of compressors running on the hydrocarbon isobutane, and German manufacturers of refrigerators, among others Bosch/Siemens, started to use these compressors. Shortly after, 35 types of refrigerators using isobutane as refrigerant were introduced by Electrolux. Thus, a comprehensive selection of refrigerators using isobutane as refrigerant was available.

At the same time it was discovered that the hydrocarbon cyclopentane could be used advantageously as blowing agent for polyurethane foam in refrigerators. This discovery was used in some German refrigerators and in many Electrolux factories. Both isobutane and cyclopentane have a very small direct impact on the greenhouse effect compared with the HFC substances. The GWP value of these hydrocarbons is app. 3, whereas HFC-134a accounts for a GWP value of 1300 (time frame = 100 years, GWP for CO2 = 1).

After this an avalanche started to slide, which in a few months forced the German refrigeration industry to convert to hydrocarbons. Also foreign manufacturers, who wanted to sell refrigerators in Germany, were forced to deliver refrigerators with hydrocarbon technology. This step was necessary, if they wanted to contribute to the selection of goods in warehouses and consumers magazines. More than 95% of the new refrigerators on the German market use hydrocarbons in the cooling system and as blowing agent for the insulating foam.

However, many people feared that an explosion accident might happen in some of the refrigerators due to the explosive mixture of hydrocarbons and air, which might appear in the cabinet. The danger that a spark from thermostat, door contact or lamp might ignite such explosive mixtures was imagined and debated.

This problem was solved by placing various potential spark-generating components outside the cabinet and to take preventive measures against any refrigerant leakage inside the cabinet.

At present, more than 20 million years of operation have been registered in Germany. According to available sources of information no accident has been registered so far.

Some people believe that the safety condition of the refrigerators has improved. Still, some people store lighter gas (for lighter refilling) in refrigerators. Unfortunately, this has caused explosion accidents in some old refrigerators where gas leaking from the gas dispenser was ignited by the thermostat or by the door contact.

In addition, people were worried about the perspectives of increased electricity consumption after the new types of refrigerators had been introduced. This might have increased the contribution to the greenhouse effect caused by an increased CO2 emission from fossil fuels utilized at power plants. Also this anxiety proved non-relevant. The energy efficiency of the new hydrocarbon-based refrigerators is at least as good as the efficiency of the old system based on HFC substances.

Refrigerators using isobutane as refrigerant are less noisy than refrigerators using HFC-134a, among others because of reduced pressure conditions in the compressor.

Another problem with HFC-134a is that it requires synthetic ester oil. It is very absorbent and it can be a problem that the oil sucks water from the air.

In Denmark the company Vestfrost quickly introduced hydrocarbon technology in the insulation foam and that i.a. took place with support from the Danish EPA.

In 1993-94, the Danish company A' Gramkow in Sørnderborg developed a hydrocarbon charging station also supported by the Danish EPA. The company is now among the largest manufacturers of hydrocarbon refrigerant charging equipment for refrigerators in the world.

Danfoss is one of the worlds leading manufacturers of hydrocarbon compressors for refrigerators and freezers. App. half of the production, which takes place in Flensburg, Germany, is laid out for isobutane application.

Hydrocarbon technology is making progress in Europe and certain developing countries, including Argentina and China. To achieve EU's environmental label it became a demand in 1996 that refrigerators should not contain potent greenhouse gases in the refrigerant or the insulating foam. This means in practice that hydrocarbons are necessary to obtain the label.

In 1998, Vestfrost was awarded the EU environmental label for a combined refrigerator/freezer and as far as we know it is the first refrigerator that has received the EU environmental label.

As far as we know, Vestfrost is the only Danish manufacturer who has converted to cyclopentane in the insulating foam. However, several other manufacturers have invested in equipment enabling the application of cyclopentane. For some of the other companies this means investments in factory rebuilding due to compulsory precautions against fire.

DTI Energy knows of another Danish manufacturer who has partly converted to cyclopentane.

The smaller Danish manufacturers use HFC as blowing agent for insulating foam. HFC is used because it still is less expensive than cyclopentane as it requires an increased amount of plastic when used. However, this aspect is being levelled by new plastics definitions.

Tonnes

HCFC-22

HCFC-141b

HCFC-
142b

HFC-
134a

HFC-
152a

R-404A

Insulating foam

0

0

7

264

0

 

Refrigerant



 

 

 

298

 

8

The consumption of HCFC and HFC substances (in tonnes) for the production of refrigerators and freezers in Denmark in 1997. The figures cover both domestic refrigeration units and commercial plug-in refrigerators and freezers. The figures are from 'Ozone depletion substances and certain greenhouse gases', the Danish EPA, 1998.

Vestfrost is the only Danish manufacturer who can charge isobutane on all production lines.

In September 1996, Greenpeace Denmark carried out a survey on hydrocarbon refrigerators and discovered that there are more than 108 designs in the Danish market. Several refrigerators are imported from Germany, Sweden, Slovenia and Italy. Greenpeace is currently busy carrying out a new survey and the temporary results show that the number of hydrocarbon refrigerators has increased to app. 271. That corresponds to app. 41% of all models in the market.

It is DTI Energy's impression that all Danish manufacturers realise that certain restrictions will be introduced in Europe as the Kyoto protocol has included HFC substances on the list of greenhouse gases that have to be reduced. The restrictions will comprise the future use of HFC substances and also that "it might become necessary to change to hydrocarbons". However, Danish manufacturers still want to produce units with HFC substances for countries demanding these and in particular for the USA, where distribution of refrigerators charged with a flammable refrigerant is not possible for the time being.

Non-HFC technology is available. In Denmark it is purely economic considerations that restrict the introduction of their use. These economic barriers mainly consist of investments in factory buildings, as rebuilding often will be necessary to secure fire-protecting areas in connection with the foaming process and charge of refrigerant. Furthermore, the investment in a hydrocarbon charging system and training of personnel will be necessary. Finally, approval of products together with accomplishment of laboratory tests for energy consumption measurements must be carried out.

It should be mentioned that new technology is being introduced in compressors. Danfoss has developed a compressor range for domestic refrigerators. These operate on isobutane and have variable speeds, which generate considerable energy savings of 30 to 40%.

The energy savings are not achieved because of the refrigerant, but rather because of the possibility of optimising control of the device. The new compressors are included in the Danfoss product range and a sales increase is expected for the next years. The price is currently somewhat higher than the price of traditional compressors.

At DTU (the Technical University of Denmark) and Aalborg University tests on a similar compressor for refrigerators have been carried out together with Danfoss and Gram. Isobutane was used as test refrigerant and also in this case energy savings of 30 - 40% were measured. In this case it was decisive to use isobutane as refrigerant, as application of HFC-134a would create a too large cooling capacity. This compressor has not yet been put into production.

Additionally, it should be mentioned that at present no hydrocarbon compressors applicable for direct current (12 V or 24 V) exist. HFC-134a is used as refrigerant in small refrigerators and freezers for trucks, yachts and other applications without main voltage. Development of direct current compressors for isobutane should be possible, but an investment from the compressor producer is necessary, which demands a market potential for these compressors.

A number of serum coolers for application in e.g. India are produced in Denmark. Sales of these coolers are co-ordinated by WHO and UNICEF, who demand the use of HFC-134a as refrigerant. A considerable number of direct current compressors are used in these coolers, which are often run by solar cells (photovoltaric).

3.1.2 Commercial refrigerators and freezers

The same companies which produce domestic refrigerators and freezers (Vestfrost, Gram, Caravell, Derby, Frigor and Elcold) account for a considerable production of commercial refrigerators and freezers. In particular, ice cream freezers and can coolers for retail shops are in question, but to a small extent refrigerators for hotels, restaurants, bakeries etc.

The production method of bottle coolers and ice cream freezers is almost the same as for domestic refrigerators. The insulating foam is produced in the same way as mentioned above. Vestfrost uses cyclopentan and the other parts use HFC.

Until now, no compressors for isobutane for commercial refrigerators have been available in the appropriate size.

In co-operation with Vestfrost, Caravell and DTI Energy, Danfoss is developing a new compressor concept for isobutane as refrigerant and with variable speed. These compressors are adjustable to most commercial refrigeration units.

The first experiences show that the compressors function satisfactorily. This project is subsidised by means of the CO2 scheme under the Danish Energy Agency. 40 can coolers and 50 ice-cream freezers will be produced for testing in retail shops. In addition, a number of prototypes will be tested.

It should be mentioned that in Great Britain several units, using hydrocarbons as refrigerant, have been produced. Compressors for CFC-12 or HFC-134 have been used, in addition with a hydrocarbon mixture of propane/butane, having the same pressure/temperature conditions. Among others, Elstar has produced wine and beer coolers with hydrocarbons as refrigerant. This company has erected thousands of such coolers and solely uses hydrocarbons as refrigerant.

According to present standard specification the amount of flammable refrigerants is limited to 150 g. It is estimated that most commercial refrigerators and freezers will have a refrigerant charge smaller than this.

3.1.3 Commercial refrigeration systems

Commercial refrigeration systems are systems that e.g. are used for cooling purposes in supermarkets, speciality shops, hotels and restaurants and computer rooms. They can also be smaller refrigeration systems for industry.

Typical commercial refrigeration systems are for instance used in supermarkets, where direct cooling has been used so far. The cooling compressors are placed in a machine room separated from the place of cooling.

Refrigerant is transmitted in long tubes into the retail shop, where evaporation takes place in the heat exchangers of refrigerators and freezers inside the shop. The refrigeration gas is sucked back to the compressors.

This principle occurs in numerous variations and sizes, from small bakery shops or butcher shops to computer offices, from hotels and restaurants to very large warehouses with more than 50 refrigeration systems.

In section 3.1.7 air conditioning systems are described, however it should be mentioned that there is no distinct difference between commercial refrigeration systems and air conditioning systems. Systems with several refrigeration locations, including air conditioning, are often seen.

Previously, CFC or HCFC based refrigerants like R-502, HCFC-22 and CFC-12 were used. In recent years many systems have been changed to HFC based refrigerants like HFC-134a or R-404a. New systems, built in recent years, are charged with HFC refrigerants as well.

In Denmark and abroad some new systems have been built recently. See more information later in this section.

HCFC-22

R-404a

Other HFCs

600

102

66

Consumption of HCFC and HFC substances in commercial systems in 1997 in tonnes (Ozone layer depleting substances and certain greenhouse gases, Danish EPA, 1998). It must be specified that consumption is classified as 'Refrigerant (other areas)' which is evaluated to be mainly commercial cooling and air-conditioning systems.
In addition, 54 tonnes of HFC-134a is used as 'refrigerant (other areas)'. The 66 tonnes of 'Other HFCs' are 26 tonnes R-401A, 14 tonnes R-407C, 10 tonnes R-402A and 16 tonnes other HFCs.


The commercial refrigeration area is the most heterogeneous one within the refrigeration industry. A large number of enterprises are involved in selling and installing refrigeration systems. The refrigeration systems are composed of standard components provided for the purpose. Tubing is often quite extensive, earlier resulting in a significant rate of leakage per year, i.e. 20 -25% of the refrigerant charge.

AKB (Authorized Refrigeration Installers Association) has contributed considerably to quality improvement by securing that the systems remain tight. Nobody knows the exact leakage rate but AKB has prepared a policy about reducing the rate. However, there are limits to how tight the systems can become and that is especially the case for direct cooling in i.a. supermarkets.

On the other hand, if indirect cooling is applied, then refrigerant filling and leakage rates can be reduced drastically.


There are many commercial refrigeration systems and therefore their commercial value is considerable. Still many old systems are operating on CFC refrigerants because a change to HFC based refrigerant would be a cost out of proportion with their age. Mainly, the newer refrigeration systems have been changed to HFC refrigerants.

It has been attempted to convert one particular system to propane, however the conclusion was that changing a CFC/HCFC or HFC system to propane is not realistic, as the required information for approval by the National Inspection of Labour in Denmark is seldom easily obtained.

Thus, it would be reasonable to continue operation with the existing systems but take appropriate precautions for leak proofness. When ready for scrapping, recovery of refrigerant is necessary for further treatment at the KMO (Danish refrigeration industry's recovery and recycling scheme) for purification and reclamation or sending to destruction.

KMO is a voluntary arrangement within the refrigeration trade and has been supported by the Danish EPA.

Natural refrigerants are substances that are already included in nature's own cycle, for instance ammonia, hydrocarbons, CO2, water and air.

Systems for natural refrigerants to be used in supermarkets have been built in Denmark and abroad. Either ammonia or hydrocarbons are used as refrigerant. As these are not permitted in the shop itself, indirect cooling must be used, i.e. a secondary refrigerant (brine).

For many years, secondary refrigerants have been used in certain refrigeration systems, among others in water/glycol mixtures or water/saline mixtures. Recently, it has been mentioned that ice slurry or CO2 under high pressure could be used. Systems with indirect cooling are more expensive that systems with direct cooling as investments have to be made in an extra pump and a heat exchanger. In return, there will be less refrigerant leakage down to app. 5% per year. Refrigerant charge is also much smaller than for corresponding direct systems.

In Sweden, there are demands for using indirect cooling. According to Svensk Kylnorm indirect cooling has to be applied if the refrigerant charge in the primary refrigerant system exceeds 30 kg. If the charged amount is between 10 and 30 kg the system has to be partly indirect which in practice means that the refrigeration of cold stores will be indirect while the refrigeration of freezers will be direct.

The Danish Energy Agency and the Danish EPA have financially supported the construction of a new refrigeration system at Schou-Epa (now called Kvickly), which is the biggest supermarket in Roskilde near Copenhagen. An ammonia refrigeration plant is used, placed in a container on the roof of the building. A water/saline mixture is cooled in the ammonia refrigeration system, which is then pumped into the shop at two temperature levels to allow cooling or freezing.

The project is carried out by Sabroe + Sarby in co-operation with DTI Energy. The system replaces more than 30 old CFC or HCFC-based refrigeration systems and energy savings amount to app. 35%.

However, energy savings in relation to a new, parallel coupled HFC refrigeration system would be insignificant and perhaps it would have a somewhat greater energy consumption.

Refrigeration systems, using ice slurry (a pumpable mixture of water, alcohol and ice, resembling thin sorbet ice) have been tested abroad. Ice slurry is a secondary refrigerant, which advantageously can be used for refrigeration purposes of up to 0/C.

Some of these plants exist in Germany, Norway and England. However, this technology does not seem to be fully developed, as some teething problems have appeared.

Commercially accessible German and Canadian ice slurry generators are now on the market. The generator functions by means of ice that is generated inside a vertical or horizontal cylinder. Afterwards a mechanical scraper scrapes off the ice. The generators are rather expensive.

DTI Energy has developed a new principle for ice slurry generators without mechanical scrapers. Pumping the ice through a traditional heat exchanger with a special surface coating generates ice slurry. The generator has been developed with financial support from the Danish EPA, and at the moment tests are being carried out at DTI Energy in co-operation with Sabroe Refrigeration.

A new "Ice Slurry Centre" has been founded and various companies are involved in the project including Sabroe, Grundfos, tt-coil, Swep, Texaco, Georg Fischer, Hans Buch, Sunwell and Institute for Applied Chemistry, DTU. DTI Energy is involved in all development activities and carries out secretariat functions and administration of the centre.

The main objective of the centre is to develop and produce components for ice slurry. Knowledge and competence are transferred through the centre to products, thus ensuring functionality of the products and optimum interplay between them. The following products are to be developed: ice slurry generator, equipment for measuring ice concentration, pumps, pipe systems and valves, heat exchangers, storage equipment etc.

The centre is supported by the Danish Agency for Development of Industry and Trade and a user group is also connected, comprising FDB (the Danish Co-operative Union), the Danish Meat Research Institute and the Danish Fishermen's Association.

Ice slurry is expected to become important to future refrigeration systems with indirect cooling in commercial refrigeration systems. Ice slurry will probably also be used for new refrigeration purposes such as direct contact freezing.

Pressurised CO2 can advantageously be used as refrigerant for freezing applications. Laboratory tests have been carried out in Denmark and systems exist abroad that use the same principle.

In the Programme for Natural Refrigerants (included in the Cleaner Technology Programme) DTI Energy is currently carrying out 2 subprojects called "Introduction of ammonia in smaller refrigeration systems" and "Information to the Danish refrigeration trade concerning the use of ammonia in smaller refrigeration systems".

The objective of the subprojects is to investigate and clarify problems in connection with the use of ammonia in small and smaller split-plants, to give advice and assign methods for plant design and to ensure that know-how is passed on to the refrigeration trade and realised in practice.

The projects include market research; description of fields of application and types of application; the preparation of safety measures, dimensioning rules, service and maintenance procedures; problem analyses regarding plant components, pipes and assembling methods; the development of laboratory equipment and tests with the same; construction and measurements carried out on demonstration plants, and reporting and participation in one-day conferences and seminars. The projects also include the formulation of a course programme and the preparation of information and instruction material.

The experimental work connected with the laboratory has become more extensive than planned. So far it has revealed that the problems against expectation not only have to do with the materials and assembly methods of the pipe system, but also in making the components operate satisfactorily with regard to refrigeration technology and acceptably with regard to energy consumption.

DTI Energy has carried out a demonstration project that was financially supported by the Danish Energy Agency. The objective of the project was to develop and demonstrate an ammonia based refrigeration plant for milk cooling at farms with reduced energy consumption and environmental impact.

In February 1998, the cooling system was put into operation at an ecological farm and it has functioned satisfactorily for 7 months. The complete installation comprises a system for cooling and storing milk as well as facilities for milk pre-cooling, drinking water heating, cooling accumulation and the utilisation of the condenser heat for preheating domestic water. Measurements have shown that the consumption of energy due to a low compressor efficiency was higher than expected, but lower than in connection with previous systems. Using ammonia and ice water as brine means that there will be no halogen-containing refrigerant leak detrimental to the environment. The plan is to change to an improved compressor. That will reduce energy consumption further.

Experience has been gained from the project that gives rise to believe that the concept can be developed to a competitive product programme. The project should be followed by new activities ensuring that the experience gained combined with innovation and new experiences from abroad are utilised for product development of future milk cooling systems in agriculture with environmental refrigerants and low energy consumption.

Various projects are being planned including a project about solely using natural refrigerants at a large city hotel.

In the course of the past couple of years, app. 75 new cold storage plants using hydrocarbons as refrigerants have been built in Sweden. They are based on a concept developed by Bonus Energi AB. An example is a new supermarket with a cooling system utilising hydrocarbons. The cooling capacity is 240 kW (for cooling) and 140 kW (for freezing). 7 semi-hermetic compressors are used. The refrigerants are a mixture of propane and ethane (Care 50") and the charge is 35 kg. As secondary refrigerants propylene glycol (for cooling) and CO2 (for freezing) are used. Bonus Energi AB was taken over by Sabroe A/S and the concept is now being marketed throughout Scandinavia, in Germany and the UK. Appendix E contains a reference list of the hydrocarbon cooling plants that have been erected by Bonus Energi AB. Linde AG in Germany has a similar concept.

It is now possible to purchase compressors for propane or propene. Bitzer compressors are used in the Bonus plants. In addition, AirCon A/S sells corresponding compressors from Dorin.

So far, no larger commercial cooling systems with hydrocarbons as refrigerants have been installed in Denmark, although several project reports have concluded that according to current Danish legislation there should be nothing against using hydrocarbons as refrigerant.

One of the reasons might be that in a discussion paper called "Without cooling most things get too hot" published by AKB in 1998, Mr. Flemming Jørgensen from Danfoss A/S warns against using hydrocarbons. FJ i.a. writes: 'Within our trade in general we do not have enough know-ledge or experience and our education and not least supplementary education of the service sector must be supplemented with knowledge, rules, legislation and ordinary common sense when using and handling hydrocarbon-based refrigeration systems'.

Therefore, it is necessary to explain if actual problems exist and if so, what the problems are by means of planning and installation of a medium size commercial cold storage plant with propane.

A demonstration project should include planning, installation and operation of a plant with 100-150 kW cooling output and with propane charge greater than 7 kg. All relevant authorities ought to be involved. A measurement programme should be carried out to determine output, operating conditions and energy consumption. Afterwards instructions concerning how to carry out the programme and who has to be asked and to whom application should be sent etc. should be prepared.
A project should also include development of a basis for qualifying (supplementary) education for refrigeration fitters and service staff.

A project proposal concerning the above has been prepared.

It must be concluded that more experience is required by means of experimental tests with commercial refrigeration systems using indirect cooling. Especially, tests with ice slurry and CO2 as secondary refrigerants are necessary.

It is important that the safety aspects are fully considered and that regulations issued by the Danish National Labour Inspection are fully observed. In that connection it is important that light is thrown on the regulations needed.

The energy efficiency of new refrigeration systems is of great importance, and the energy consumption must not exceed the consumption of new HFC refrigeration systems.

It is important that the costs of refrigeration systems using brine systems (secondary refrigeration systems) are reduced to facilitate a wider use in the future.

It should be mentioned that the application of free cooling i.e. from outside air or harbour waters also is a possibility. Such measures might reduce energy consumption for refrigeration systems during some months of the year, as outside air e.g. can directly cool a room or harbour water can directly cool process water.

Evaluation of possibilities for using natural refrigerants within commercial refrigeration:

For future refrigeration plants the following can be stated:

The plants can be designed for ammonia as well as for hydrocarbons according to the safety measures required. In public premises it will normally be possible to use indirect cooling while indirect cooling can be used in many other cases.
In the future large commercial refrigeration plants can be designed as ammonia or propane refrigeration plants using indirect cooling. Regarding fields of application large supermarkets could be mentioned.
To some extent very small commercial refrigeration systems could be systems using hydrocarbons or ammonia with direct expansion. However, it is demanded that certain safety rules and firm procedures are issued/developed. Among others, the safety rules include a maximum amount of charge, e.g. 1.5 kg (for direct expansion). Suggested field of application is small refrigeration stores and refrigeration furniture in delicatessens, etc. Direct cooling can be used in connection with storage rooms with no public access.
- The intermediate sized area is where the most important problems exist. Because of economic and safety reasons it might be a problem to build refrigeration systems using indirect cooling. Small everyday stores could be mentioned. As previously described, a number of development projects are presently in progress and they aim at developing new technology to narrow this rather grey zone area. Likewise, direct cooling can be used in connection with storage rooms with no public access.

3.1.4 Industrial refrigeration plants

Normally, industrial refrigeration plants are very large systems, which are used for process cooling within the foodstuff industry or in the chemical/biochemical industry. In Denmark, traditional ammonia refrigeration plants are used for such fields of application.

Almost all dairies, slaughterhouses and breweries make use of ammonia refrigeration plants. Sabroe Refrigeration is the leading manufacturer of industrial refrigeration plant, using mainly ammonia as refrigerant. Also Gram Refrigeration (York International) is known as supplier of industrial refrigeration systems using ammonia.

However, many industrial refrigeration plants use CFC, HCFC or HFC refrigerants, and in most cases this might have been ammonia refrigeration plants as well.

A tendency of using indirect system solutions prevails, for example in foodstuff industries, aiming to reduce refrigerant charge and to avoid ammonia outlet in areas of work etc. Hence, development of plants, using CO2 as refrigerant, will be required.

With financial support from the Danish Energy Agency, the company Sabroe Refrigeration and DTI Energy have developed a refrigeration plant, using solely water as refrigerant in the compression process. After production, the 2 MW demo plant was placed at Lego for cooling of casting machines producing plastic Lego bricks.


The efficiency of the plant is very high, and the energy consumption is app. 30% lower than for a newly optimised ammonia refrigeration plant. The plant has been fairly expensive to produce, and some years may pass before this technology is completely developed. It is expected that the Lego project will be followed by other projects involving the Danish Energy Agency.

3.1.5 Mobile refrigeration systems

Mobile refrigeration systems are refrigeration systems installed in cars, trains, aircraft, ships or integral reefer containers

Integral reefer containers
In Denmark the major field of application lies within integral reefer containers. The company Mærsk Line is the world leading carrier of refrigeration goods and has app. 40,000 cooling reefers in traffic on a global level.
Previously, integral reefer containers were quipped with a CFC-12 refrigeration system, and many old containers still use this equipment. Many new containers are changed to HFC-134a.

Since 1993, all new refrigeration systems have been installed with HFC-134a refrigeration plants. In Japan HCFC-22 is used for this purpose and in the USA substances like R- 404a and HFC-134a are used. Due to hard weather conditions at sea, the leakage rate of this type of refrigeration system is rather high.

Previously, CFC-11 was used in the insulating foam, but is now replaced by HCFC-141b.

Mærsk Container Industri A/S now produces integral reefer containers in Tinglev, Denmark, and production is considerable.

Thermo King Container Denmark A/S in Langeskov produces refrigeration systems to be installed in integral reefer containers.

Supported by the Danish EPA, DTI Energy in co-operation with industry has accomplished a survey aiming to examine the construction of future integral reefer containers.

The use of flammable refrigerants or ammonia for this purpose is problematic. At the moment, the range of natural refrigerants is thus limited to cover CO2 and possibly air as refrigerant.

In the course of the project the development of a prototype, testing CO2 as refrigerant, was suggested. Besides it is recommended to try using vacuum-insulation methods.

A Cleaner Technology project seems relevant for this area, and DTI Energy has in co-operation with industry formulated a project proposal concerning this matter.

A/C systems in cars
Previously, CFC-12 was used for this purpose, but in recent years HFC-134a has been used.

As Denmark has neither any car industry nor special hot climate conditions, no remarkable activities in connection with automotive air conditioning have been registered. However, the company A'Gramkow has produced charging equipment for the car industry. Still, in cars is an increasing area of application which might become standard equipment in the future.

In co-operation with important car manufacturers Danfoss has participated in an EU-project with the aim of developing a new type of system using CO2 as refrigerant. Danfoss has developed a new compressor for this purpose.


It should be mentioned that in some countries hydrocarbons are used in car air conditioning systems. This is for example the case in Australia, where thousand of cars are using these refrigeration systems. Apparently, a hydrocarbon mixture is used together with conventional equipment, originally designed for CFC-12 or HFC-134a.

The possibility of fire and explosion accident occurrence in connection with application of hydrocarbons in car air conditioning systems has been debated. Hydrocarbons could be a natural choice, as several kg of hydrocarbons in the form of petrol, diesel oil and propane gas are already present in the car.

A/C systems in air planes
For many years, a cold air refrigeration system was used for cooling passenger cabins in ordinary air planes. A simple joule process is used, where air is compressed and cooled by exchange with the surroundings. Afterwards, the air expanded in a turbine, whereby it turns cold. The energy efficiency of the process is not remarkably high, but it is used in planes because of the light weight of components.

A/C systems in trains
In Germany a project concerning a cold air refrigeration system for trains has been carried out. App. 60 units have been produced for ICE trains.

3.1.6 Heat pumps

The function of heat pumps is similar to that of refrigeration systems, as heat is tapped from a source (for instance fresh air, soil, stable air, process water, etc.). At higher temperatures this is removed to a heat carrier, for example central heating water.

The following three main types of heat pumps exist in Denmark: domestic heat pumps, stable heat pumps or industrial heat pumps.

Domestic heat pumps are used for space heating and for heating of water for domestic use. In Denmark, heat pumps are almost solely used in single family houses, but in Sweden and Norway a number of very large heat pumps are connected to collective heat supplies.

In Denmark, there are about 12 manufacturers of such heat pumps, and quite a number of Japanese units are imported.

Until now artificial refrigerants have been used, however the Danish producer Lodam has developed heat pumps using propane as refrigerant. In 1997, Lodam won a competition in Holland and therefore they have to deliver 400 heat pumps utilising propane to Dutch customers. This is a break-through for Danish, environmentally friendly heat pump technology. Lodam's heat pump technology has been taken over by the Swedish company called Nibe. They will continue the production of heat pumps using propane.

Criteria have been accepted for the Nordic environment label concerning domestic heat pumps. According to these criteria no considerable greenhouse gases are allowed in the refrigerant of the heat pumps if they are to obtain the environmental label.

Like domestic heat pumps stable heat pumps are compact units utilising surplus heat from livestock. This heat is utilized for heating the house and/or for preheating of water for cleaning etc. in the stable. It is generally the same companies that install domestic heat pumps and stable heat pumps.

The Danish Energy Agency has financially supported a demonstration project on stable heat pumps.

Sabroe and Gram produce industrial heat pumps, and among other substances ammonia is used as refrigerant.

3.1.7 Air-conditioning systems

So far, no small air-conditioning systems for single family houses have been produced in Denmark, as our climate does not necessitate them in private houses. However, an increased marketing of air conditioning systems (often Japanese) in Denmark has been registered.

Previously, foreign manufacturers have used R-502 and CFC-12 and later HCFC-22 for this purpose and many foreign manufacturers are changing to HFC-based refrigerants, including HFC-134a and R-507C.

A foreign manufacturer (DeLonghi) has produced app. 60,000 air conditioning systems using propane as refrigerant.

IMI in the UK has sold plants with Care 50 (mixture of propane and butane). Models that can be mounted on walls and under ceilings are in question. The cooling output is between 2 and 10 kW.

It should be mentioned that a Danish manufacturer of dehumidifiers, Dantherm, uses HFC refrigerants.

The situation is different for large air conditioning systems in office buildings, hospitals etc. Here refrigeration systems (chillers) are installed for distributing cold water in the building. Air is cooled in heat exchangers by means of the cold water.

Various refrigeration systems are available for this purpose, and previously CFC-11 and other chemical refrigerants have been used. Ammonia is an excellent choice for this purpose and a system has been built/ installed at the main post office in Copenhagen. Furthermore, the system is equipped with a sea water heat exchange to utilise free cooling by means of cold harbour water for several months of the year, thus saving energy.

Appendix B includes a reference list of Sabroe's ammonia refrigeration plants for chillers built in Denmark in the later years. Since 1990, 114 plants have been installed in hospitals, in large office buildings, within the process cooling industry, at Copenhagen Airport, within the foodstuff industries and at shopping centres.

Appendix C includes a similar reference list from Gram Refrigeration (York International) of ammonia chillers. 35 plants have been constructed since 1993, and these are installed in hospitals, in large office building, industries etc.

Similarly, it is possible to utilise propane in chillers for air-conditioning. Bonus Energi AB has erected app. 75 plants in Sweden. Appendix E contains a reference list of the plants.

Water vapour compression technology can also be used in connection with A/C. DTI Energy is involved in mechanical water vapour compression operated by electric energy and is also involved in thermal water vapour compression utilising hot waste water to produce cold water for air-conditioning purposes. That takes place by means of ejector technology, where water is the working medium and also the refrigerant. Waste water is derived from decentralised power stations or industrial processes.

3.1.8 Cryogenic systems

The application of low temperature systems is relatively small. Refrigeration equipment is produced, which can cool laboratory tests and other equipment to very low temperatures.

Heto-Holten produces laboratory equipment, including equipment for freeze-drying and low temperature freezers (cryogenic systems) for hospitals etc.

Normally, the equipment consists of a two-step cascade refrigeration system, where the first step is an R-404a or an R-403B system. During the first step of the process, temperatures down to app. -50/C are reached. During the second step hydrocarbons are used as refrigerants, either ethane (R-170) to app. -80 to -90/C or ethene (R-1150) to app. 100 to - 120/C.

Some foreign competitors use HFC-23 at the lowest step.

It should be possible to use propane during the first step. This would hardly influence the safety aspects, as flammable refrigerants are used already. However, compressors approved for propane are required and tests need to be carried out. There are indications that this is the case. According to the Danish agent of Dorin compressors they can be used for propane.

Possibly, other Danish companies produce cryogenic systems.


3.2 Polyurethane foam

The consumption of HCFC and HFC substances for production of polyurethane foam in Denmark in 1997 appears from the following table:

 

 

HCFC-22

HCFC-141b

HCFC-142b

HFC-134a

HFC-152a

Insulation in refrigerators

0

0

7

264

0

District hearing pipes

0

0

0

0

0

Other insulation material

0

440

4

0

0

Other rigid foam

0

145

6

0

0

Jointing foam

0

0

0

44

5

Flexible polyurethane foam

0

0

0

40

10

Consumption of HCFC and HFC for production of polyurethane foam for various applications.
Consumption is stated in tonnes, and the figures have been taken from Cowi's survey: Ozone depleting substances and certain greenhouse gases 1997, Danish EPA, 1998.


As it appears quite an amount of HCFC is still used for foaming polyurethane foam. Especially HCFC-141b is in question. In the autumn of 1998, (according to trade sources) that lead to a shortage of the substance as several countries (including Denmark) has encountered a HCFC cap which has been laid down in the EU. Therefore, there is a limited amount to be used in the final part of 1998 and there has been a substantial price increase.

3.2.1 Insulating foam

As already mentioned in chapter 3.1.1, some amount of HCFC and HFC is used for insulation of refrigerators and freezers, and the available alternatives have already been described. Hence, this application will not be discussed in this chapter.

District heating pipes
More than half of the global production of district heating pipes takes place in Denmark by ABB, I.C. Møller, Løgstør Rør, Tarco Energy and Dansk Rørfabrik (Star Pipes).


Previously, the consumption of CFC and HCFC was considerable. Thus, approximately 820 tonnes of CNC-11 was used in 1986. Today the insulating foam is blown by means of hydrocarbons, especially cyclopentane. In addition, some district heating pipes are produced with CO2.

The Danish EPA has in co-operation with the industry obtained approval of the above mentioned type of district heating pipes for future projects by means of World Bank funding. This has contributed to a form of standardisation of pentane blown district heating pipes.


Mads Madsen from European District Heating Pipe s Association informs that Danish enterprises now deliver approximately 65% of the world production of district heating pipes. A small amount of this production takes place at subsidiary companies, e.g. in Poland.

About 1500 people are employed in district heating pipe factories in Denmark. In addition, some enterprises work with pipe laying and assembly of entire energy systems, etc. Enterprises, which are sub-contractors to district heating pipe enterprises, can also be mentioned. As can be seen, the importance to Danish economy and employment is considerable.

Insulating panels
At least two companies (D.C. System Insulation and Prepan, previously Dansystem) produce sandwich-insulating panels for cold store houses etc.

Especially HCFC is used for this production, as some panels are also produced with CO2 to which a small amount of HFC had been added for export to Sweden, who has banned the use of HCFC panels. The exact amounts of HCFC are not known at the moment, but it is expected that a large amount of the HCFCs in the column other insulation foam will be used for this purpose.

In 1986, approximately 140 tonnes of CFC-11 were used for this purpose.

Alternatively, hydrocarbons, including cyclopentane, could be used. However, a large investment in production equipment is required. Certain foreign countries produce panels with hydrocarbons. In Finland e.g. Hurre Group Oy and Makroflex Oy produce sandwich-insulating panels by means of hydrocarbons.

Another alternative is to use CO2 (water blown) foam. Compared to other solutions, the insulation efficiency is poorer.

It is to be imagined that vacuum insulation is useable for this purpose in the future. A possibility could be production of sandwich-panels with rigid polyurethane foam with open cells. Afterwards, a vacuum pump will help to keep the pressure down in the insulation material. The foam itself is produced by blowing with CO2. Major efforts are required to develop this technology.

The greatest barrier against the introduction of hydrocarbons is the large investments required for rebuilding production equipment. Relatively small manufacturers are involved and relatively large investments will be required from them.

Integral reefer containers
HCFC substances are used for production of reefer containers. The consumption of HCFC for this purpose in unknown, as it is included in the category other insulation foam in the Environmental Project No. 342. This is a relatively new production in Denmark.


The production could be changed to hydrocarbons (cyclopentane). However, some requirements were to be considered, including safety precautions for using cyclopentane as blowing agent. Furthermore, it should be considered that a possible reduction of insulation properties will change the construction of containers. Mærsk Container Industri A/S has stated that the transition to cyclopentane could lead to reduced insulating properties of up to 10%.

The greatest barrier against introduction of hydrocarbons is connected to the disadvantages caused by production stop, uncertainties about quality, security of working environment and the economical consequences hereof.

Another possibility would be to use vacuum insulation, where rigid polyethane foam with open cells are used. A project has been worked out in co-operation with DTI Energy and industry concerning this matter. Comprehensive changes in construction and production are required if switching to this technology, and examinations and tests will be needed.

Other types of insulation foam
A number of minor manufacturerss of polyurethane foam use either HCFC or HFC for a number of purposes. It might be too expensive to invest in hydrocarbon technology, as large investments in fire protection are necessary.

Alternatively, foam blown by CO2 could be used, however the insulation conditions would decrease, compared with foam, blown by HCFC or HFC. In connection with certain applications the insulation properties are not decisive. That might be in cases where the construction implies that considerable heat bridges already exist or it can be in cases where there are no greater temperature differences.
In connection with the first item it can be mentioned that industrial gates with CO2 blown polyurethane foam are produced at Nassau Doors.

Another example is foaming of insulation material at Norfrig A/S who produces cooling boxes for lorries and semi-trailers. According to Mr. Chris Ungermand, Shell Kemi A/S, water blown foam is used. They have succeeded in developing a material with the same insulating properties as when HCFC-141b was previously used. That has happened by using glass fibre reinforced barriers on the sides. In that way diffusion of COs out of the foam and diffusion of air into the foam is avoided.

The company Tectrade A/S has also developed a new type of CO2 blown foam (often called water blown foam) where a finer cell structure leads to improved insulating properties.

Many of the smallest manufacturers of insulating foam have stopped producing the foam themselves. Instead they purchase "block foam" which is then cut to suit certain purposes. Often the foam is only a smaller part of a larger complex machine.

There is one Danish manufacturer of block foam and the company is called LM Skumplast. The company has replaced HCFC-141b with hydrocarbons (isopentane) for foaming. The plant has been designed by Tectrade A/S.

3.2.2 Jointing foam

Baxenden Scandinavia A/S is manufacturer of aerosol cans with sealing foam and produce many different kinds. Previously, CFC or HCFC substances were used as propellant in these cans, but this has now been banned. In 1986 an amount between 575 and 800 tonnes of CFC and HCFC was used for this purpose.

Baxenden very soon introduced an alternative can, which used propane and butane as propellants. This system was introduced on the Scandinavian market, and since 1987 only systems operating on hydrocarbons have been used on this market.

The situation is different for other markets, including Germany. A maximum of 50 g flammable propellants may be stored in the cans, i.e. max. 50 g propane + butane.
Thus, it is necessary to supply an amount of HFC-134a (a 700 ml can normally contains 100 to 175 g propellant).

This derives from an agreement, made by European manufacturers, but with the exception of Scandinavia. In other parts of the world hydrocarbons are used.

Only cans with pure hydrocarbon propellants are delivered to countries, used to work with this propellant, and where safety precautions concerning ventilation etc. are kept. Accidents with hydrocarbon based cans have occurred. This has happened in cases, where safety precautions have not been kept, and where use has taken place in small rooms, where fire has been ignited by a match or a lighter.

However, this danger also consists for cans using HFC substances, as this propellant, due to the content of hydrocarbon and HFC-152a, is flammable as well.
There are 35 manufacturers in the world, and competition is hard. Thus Baxenden cannot independently decide the technological trend, but may produce cans with HFC substances to other countries than Scandinavian.

Cans with pure hydrocarbon propellants are considerable cheaper than cans with HFC substances. The propellants have different qualities, thus a price comparison alone amongst the cans is not possible. The joint foam achieves different qualities depending on the propellant.

3.2.3 Flexible polyurethane foam

In Denmark there are two large manufacturers of flexible polyurethane foam, viz. Bdr. Foltmar and K. Balling Engelsen.

The main part of production is 'water' blown, i.e. a small quantity of water is added during production. A chemical reaction between water and isocyanate will produce CO2, which is the actual blowing agent.

Some of the production has traditionally taken place using CFC-11 and later with HCFC substances as propellant. Especially soft and light quality items for the furniture industry should be mentioned.

In recent years a mixture of HFC-134a and HFC-152a has been used as propellant for this production.

Only CO2 blown foam is used in the other Nordic countries. An agreement has been made stating that foam with a density less than 23 kg/m3 should not be produced. Hence, no physical blowing agents are required.

Abroad a certain technology has been developed. Liquid CO2 is used for production of flexible polyurethane foam in these qualities, and some systems have been installed, amongst others in the USA and in Italy. The most important barrier against converting to this industry is investment in new machinery.

At least two manufacturers of the new technology should be mentioned, e.g. Canon (Italy) and Bayer (Germany).

Danish manufacturers of flexible polyurethane foam inform that there is also a barrier in connection with quality, as some quality problems with the new CO2 technology have appeared.

According to manufacturers of the above blowing technology equipment the quality of the new foam is satisfactory.

In certain countries (also in the EU) methylene chloride is used for production of flexible polyurethane foam. From a labour protection point of view this is not conceivable for application in Denmark.

3.3 Fire extinguishants

In connection with the global phase-out of Halon, a number of chemical substitutions have appeared, including one, which is based on HFC-227 (e.g. Great Lakes FM-200). These are marketed rather intensively in many countries of the world, and this has also been tried in Denmark.

However, in Denmark the use of halogenated hydrocarbons for fire extinguishing is banned. The substances Halon-1301 and Halon-1211 were excepted from this, but they are now being phased-out parallel with the CFCs etc.

Danish enterprises have developed impressive alternative technologies for fire extinguishing. Especially Inergen, which is developed by Dansk FireEater. It consists of inert gases, i.e. argon, nitrogen and some CO2. Inergen can be used for total room flooding systems in computer rooms, control rooms, power stations, engine rooms, etc.

Ginge-Kerr Danmark A/S has a similar technology called Argonite, which consists of argon and nitrogen. In addition, this company has developed a water mist technology.

The technology of using inert gases for fire extinguishing purposes has become a remarkable success, also on an international level. Foreign multinational companies, such as Wormald, is marketing Inergen.

Other alternatives for chemical fire extinguishing have been developed, such as the use of CO2 or foam for fire extinguishing purposes in engine rooms on ships or cargo vessels, improved detectors combined with manually operated fire extinguishing etc. However, giving full details on this topic is beyond the scope of this report.

This entire area has been described in detail in a report published the Danish EPA in 1995: Environmental Report No. 312: Going towards Natural Fire Exhinguishants, Experience from Danish Industry.

3.4 Propellant in aerosol cans and foghorns

The Aerosol Statutory Order, published by the Danish EPA, bans all application of HFC substances for use in aerosol cans.

The ban does not apply for medical aerosol cans or foghorns, as medical products are excluded as an exception and the publication does not regulate the contents in aerosol cans, where only gas is emitted from the can. However, a revision to include foghorns has been announced by the Danish Minister of Environment and Energy

Medical sprays
CFC-11 and CFC12 are still used as propellant in medical sprays, and especially in astma sprays. At the end of the 1980s the consumption of these products amounted to app. 29 tonnes of CFCs. The products are not manufactured in Denmark.

Alternative products have been available for many years, for instance self-inhalated astma powder. However, not all astma patients are able to inhalate themselves.

Astma sprays with HFC substances as propellant have been developed.

Foghorns
Foghorns with HFC-134a as propellant can be bought. The horn is an aerosol can provided with a plastic horn, which is able to make a loud noise.

Is is estimated that most foghorns are used by the audience at football matches, however they are also used on sailing boats as alarm horns to warn other boats.

Greenpeace Denmark has found non-HFC containing alternatives on the market. These alternatives are available in several types, where the one type uses isobutane as propellant. The other type uses compressed air, and re-loading is possible at petrol stations or by means of a hand pump.

Foghorns operating by means of an electric compressor are also available. Finally, manually driven alarm horns, which can be blown up or may be activated by means of a rubber ball, are available.

3.5 Other fields of application

There is a small consumption of HFC in special cans for cooling electronic components during repair of electronic equipment. The flow of liquid HFC cools the component that the liquid drops come into contact with.

This method enables diagnosis of a defective component. The consumption is probably modest, app. 0.5 tonnes per year. According to Naturvårdsverket in Sweden CO2 is used for this purpose, and equipment is supplied by AGA.

DTI Energy has no knowledge of other fields of application for HFC substances in Denmark.

However, it should be mentioned that in South East Asia the so-called Pushn chill beer cans were planned to be marketed. These cans are chilled by means of direct evaporation of HFC-134a in the can, whereby the beer is chilled. This subject has been addressed by the press during the summer of 1997 and European ministers of environment have opposed this application of HFC substances.

The company behind the self-chilling can has recently announced that CO2 will be used as refrigerant instead of HFC-134.


 

 

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