ABSTRACTS

THE FUTURE OF REFRIGERATION
Ronald P. Vallort, ASHRAE President
Ron Vallort and Associates
502 Forest Mews Drive, Oak Brook, IL, USA

Engineers, technicians, and food scientists have continually sought to safeguard food’s wholesomeness. While technology has made significant contributions to this end, it will have to make even greater strides in the future. Concerns for the environment, energy conservation and food safety now drive the technical community. The people of the future need: refrigeration equipment that is earth friendly both in emissions and energy consumption, cogeneration applications that will provide additional energy and lower cost refrigerated storage facilities that have both a low initial cost and a technological match with the location’s infrastructure. Engineers, scientists and technicians have a pressing mission ahead of them to advance the arts of refrigeration and HVAC in a way that will benefit both the earth and its inhabitants.
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Importance of Natural Refrigerants in Safeguarding Climate System
and Ensuring the Sustainable Development
Rajendra Shende, Head of OzonAction Programme, UNEP DTIE,
Tour Mirabeau, 39-43, quai Andre Citroen, 75739 Paris Cedex 15, France
Fax: +33-1-44371474; e-mail: rmshende@unep.fr

In my talk today, I would like to focus on the role of refrigeration in the human development, the way refrigeration and air conditioning industry has responded to the challenges of the climate change and ozone layer depletion and how the industry and the governments could further contribute to sustainable development through the technology innovation and appropriate policies.
We are at extremely vibrant and guessing moments of the 21st century. I am not only talking about the soaring oil prices and the exploding thirst for energy in emerging developing countries like China and India, but also the fast accelerating concentration of Green House gases in the atmosphere that has no historical parallel in last million years of the human existence. The threat to our climate system is now real and the consequences could be devastating. A majority of the scientist’s around the world have arrived at this consensus through the reports of more than 2000 scientists of the Intergovernmental Panel on Climate change. There is near agreement, which is rare in case of international politics, among the leaders of the developed and developing countries that climate change is the most looming threat to civilisation today apart from terrorism and viral diseases. There is agreement that actions are needed.
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AMMONIA – YESTERDAY, TODAY AND FOREVER
S Forbes Pearson
Star Refrigeration Ltd, Thornliebank Industrial Estate,
Glasgow G46 8JW, United Kingdom
Fax: 0044 141 638 8111, email: star@star-ref.co.uk

Ammonia is a unique substance by virtue of its excellent thermodynamic properties as a refrigerant and the benefits it bring to the environment.
The reason ammonia has continued in use to the present day lies in its thermodynamic properties. It is instructive to compare properties of ammonia with those of R-134a, the only single component HFC in common use today, water, which is a theoretically ideal environmentally friendly refrigerant, and propane, which is a flammable hydrocarbon having properties otherwise rather similar to ammonia. From Table 1 it can be seen that water is very difficult to use as a refrigerant because of the enormous swept volume required. R-134a is significantly worse than ammonia and propane in terms of required swept volume but is not impracticable. Coefficients of performance taken from the 1997 ASHRAE Handbook Fundamentals show that there is not much to choose between the three practical refrigerants but ammonia is the best. Ammonia would tend to appear even better in a comparison of coefficients of system performance because its transport and heat transfer properties are better. The only refrigerant having significant global warming potential is R-134a.
It seems clear that ammonia will continue to be used as a refrigerant for the foreseeable future. Future applications of ammonia and the scale of its use compared to other refrigerants are not so clear. For small, fully-sealed, systems there would seem to be no point in using ammonia, which is not a good electrical insulator and which, by reason of its relatively low mass flow, would not provide good motor cooling. Such systems will probably use hydrocarbons where national and local regulations permit and halocarbons where they do not.
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Ammonia Refrigeration Systems – the Necessity,
Risks and 150 years of Operation.
Anders Lindborg
Ammonia Partnership AB, Nyponv. 24, 260 40 Viken, Sweden
Tel +46 42 238155, Fax +46 42 238170, alg@ammoniapartnership.se

The picture of the future use of ammonia refrigeration is light when modern codes and standards are used to full extend. However there are still many old doubtful systems in operation even in devel-oped countries. These shall be looked after by experts and improved if required. In many cases it may also be necessary to carry out replacements or close down systems. The developing world is strongly depending on ammonia refrigeration and will need knowledge and economical support to improve safe operation. The community cannot afford leaks which are observed by neighbours. The media will keep us informed, when there is a leak on one side of the Atlantic Ocean, the other side will get the smell next day.

We need to produce information to the community about ammonia, build up confidence and never let our neighbour smell the ammonia. If we promise ourselves this the future for ammonia refrigera-tion is bright. Modern society cannot afford to live without ammonia refrigeration.
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CHARGE MINIMIZATION IN AMMONIA REFRIGERATION SYSTEMS
Pega Hrnjak
Professor and Co-Director Air Conditioning and Refrigeration Center
University of Illinois, Urbana Champaign
1206 W. Green St., Urbana, IL 61801, USA
Fax: + 1 217-333-1942, e-mail: pega@uiuc.edu

This paper presented analysis of the potentials for charge reduction in ammonia systems and strategies to achieve that objective. Besides addressing secondary loops and cascades and ways to reduce liquid quantity in the vessels, focus was on the heat exchangers. Besides spray evaporators, plate and microchannel heat exchangers are identified as the most rational approaches.Specifically, the objective of this work was to show the benefits of using microchannel heat exchangers for ammonia. Charge reduction and excellent ratios of heat transfer to volume, mass and surface area, are demonstrated.An ammonia chiller was constructed and charge, heat transfer, and pressure drop measurements were taken for two types of condensers: a serpentine flat macro tube and a parallel flow microchannel tube. Overall condenser performance was quantified in terms of heat capacity, refrigerant and air side pressure drops, U values, and refrigerant inventory. The charge per condenser capacity ratios of the two condensers are an average of 76 % less for the microchannel. The experimental microchannel chiller has an 18 g system charge per kW evaporator capacity at similar conditions to the chiller ratings. The other smallest commercially available air-cooled ammonia chillers all have ratios greater than 100 g/kW.The void fraction correlations applied to ammonia gives total condenser charge predictions with an average error of 9-12 %. This paper also presented new data for void fraction of ammonia in microchannel tubes.
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Heat Pump Systems with Ammonia as Refrigerant
Hermann Halozan
Institute of Thermal Engineering, Graz University of Technology
Inffeldgasse 25 / B, A-8010 Graz, Austria
Phone: +43 316 873-7303 (Fax: -7305)
E-mail: halozan@iwt.tu-graz.ac.at

Heat pumps offer the possibility of reducing energy consumption significantly, mainly in the building sector, but also in industry. The second law of thermodynamics shows the advantages: While a condensing boiler can reach a primary energy ratio (PER) of at best 105 % (i.e. the boiler efficiency ?B; the theoretical maximum would be 110 %, based on the lower calorific value), heat pumps achieve 200 % and more. Presently about 150 million heat pumps with a thermal output of 1800 TWh/a are in operation world-wide, reducing CO2 emission by about 0.18 Gt/a. The potential for reducing CO2 emissions assuming a 30 % share in the building sector using technology presently available is about 6 % of the total world-wide CO2 emission of 24 Gt/a. With future technologies up to 16 % seem possible. Therefore, heat pumps are one of the key technologies for energy conservation and reducing CO2 emissions.
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AMMONIA IN SMALL CAPACITY HEAT PUMP AND REFRIGERATION SYSTEMS
Bjorn Palm,
Royal Institute of Technology,
S 100 44, Stockholm, Sweden
Phone: +46 8 790 74 53, fax: +46 8 20 41 61, e-mail: bpalm@energy.kth.se

Ammonia has so far been used primarily in large size systems, e.g. industrial and commercial refrigeration plants. For small capacities, halogenated hydrocarbon systems have totally dominated the market. As focus is directed towards natural refrigerants, due to the ODP and GWP of the halogenated hydrocarbons, it is of interest to investigate the possibilities and possible advantages, and perhaps disadvantages, of using ammonia also in small capacity systems.This paper reports on the initial phase of an investigation concerning the possibilities of designing a small capacity (<10 kW) heat pump or refrigeration system using ammonia as refrigerant. The investigation includes a market search for suitable components. The system is designed to mimic typical domestic heat pumps on the Swedish market. In the design, special attention is paid to minimization of the refrigerant charge and material compatibility.
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WATER CHILLERS WITH AMMONIA FOR BUILDING SERVICESANDY PEARSON
Star Refrigeration Ltd,
Thornliebank Industrial Estate, Glasgow, G46 8JW, UK
Fax: +44 141 638 8111, e-mail: apearson@star-ref.co.uk

In recent years several successful projects in the City of London have proved ammonia to be a viable alternative to standard chillers, particularly where there is an emphasis on reliability or energy efficiency, or where there are particular constraints such as noise or space which predicate the design of a special package. Ammonia is not, however, the correct choice for all applications. This paper addresses the design issues which need to be considered before selecting ammonia, and then provides guidelines on how best to incorporate the chillers into the building.
These systems can give significant improvements in the energy efficiency of the installation in comparison with standard chiller arrangements. However the greatest energy savings are still made when air conditioning loads are minimised and chillers are not run unnecessarily.
Further developments which would make ammonia more widespread are also discussed.
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REMARKS ON THE USE OF AMMONIA IN AIR-CONDITIONING SYSTEMS
Ivo Eiermann, Arnd Hilligweg
Nuremberg University of Applied Sciences
Department of Mechanical Engineering
Kesslerplatz 12, D-90489 Nuremberg, Germany
Arnd.Hilligweg@fh-nuernberg.de

Considering its use in HVAC chiller applications ammonia must compete with established synthetic refrigerants like e.g. R407C on the one hand and hydrocarbons like propane, iso-butane and pro-pene on the other. Here an assessment of ammonia‘s potential use in air-conditioning systems is pre-sented for selected capacities and criteria. Thermodynamical and ecological properties are compared and potential riscs are valuated regarding current European regulations. Coefficients of performance and economical aspects (Eiermann, 2004) are discussed.
Depending on application and installation site the combination of refrigerant and chiller must be valuated individually and in detail. We suggest that this should be done following the order of this article. Future use of ammonia as a refrigerant in HVAC applications depends on industry’s ability to offer chillers genuinely designed for the specific demands of this particular installation situation.
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ENERGY PERFORMANCES USING AMMONIA AS REFRIGERANT
IN A LARGE SUPERMARKET
Assaad Zoughaib, Denis Clodic
Ecole des Mines de Paris, Center for Energy and Processes
60, boulevard Saint-Michel – F 75272 Paris Cedex 06
Fax +33 1 46 34 24 91, e-mail: assaad.zoughaib@ensmp.fr

Commercial refrigeration systems for large and medium size supermarkets are known as highly emissive systems. Typically the emissions range from 15 up to 30 % of the refrigerant charge per year. Those high emission rates are related to the large number of fittings, expansion valves, and poorly accessible refrigerant lines implying difficult leak tightness control. Moreover, oil return may be difficult, specially for large supermarkets, leading to possible significant oil flush coming back to the compressors, leading to compressor failures, and emissions during servicing [1].
In order to limit refrigerant emissions, indirect systems are seen as a key option in order to lower the refrigerant charge and to avoid any refrigerant emissions in the sales area. Indirect systems also allow broadening the refrigerant choice but, one significant issue remains: are these systems as efficient as direct expansion systems?
In this paper, performances measurement of ammonia indirect systems operating in a large supermarket are presented. A comparison with typical direct expansion systems shows that energy efficiency of both systems are in the same order of magnitude.
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Limited Charge Shell and Tube Ammonia Spray Evaporator
with Enhanced Tubes for Thermal Storage System
Z. H. Ayub(a), M.-C. Chyu(b), A. H. Ayub(c)
(a)Isotherm, Inc., 7401 Commercial Blvd., East
Arlington, Texas 76001, USA
Fax: 817-472-5878; e-mail: zahid@iso-therm.com
(b)Department of Mechanical Engineering, Texas Tech University
Lubbock, Texas 79409, USA
(c)Rose-Hulman Institute of Technology, Mechanical Engineering Department
5500 Wabash Ave, Terra Haute, IN 47803, USA

A low charge ammonia spray evaporator was designed for a process cooling application at a chemical plant. At off-peak hours the chilled water is stored in a 2,500 m3 insulated tank that is part of a thermal storage system to reduce peak demand. With the existing chillers the water temperature was at its best never lower than 4.4?C. Therefore, the minimum storage tank temperature achieved was between 5.6-7.2?C.
Design requirement was to cool water to 2.2?C without risking tube freeze-up. To meet this requirement a shell and tube spray evaporator was proposed, designed and fabricated. Doubly enhanced carbon steel tubes were employed. Field results showed good correlation with the design criterion. Spray evaporators work effectively if the feed ratio is appropriate and that no section of the bundle is starved of liquid refrigerant. With this in mind appropriate refrigerant distribution system was designed. A comparative study is presented here to show various aspects of spray evaporator versus a flooded evaporator of equal capacity. Field results showed exceptional performance under different seasonal conditions. Water outlet temperature as low as 0.6?C has been recorded and there are confirmed reports of storage tank temperature as low as 1.7?C.
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Module welded Plate Heat Exchanger within the NH3 Refrigeration circuit
– effective technique for using at flooded and dry expansion applications
Wolfgang Dietrich
thermowave GmbH, Eichenweg 4, D-06536 Berga, Germany
Fax: +49 (0) 34651 418-13, w.dietrich@thermowave.de, www.thermowave.de

The lecture at beginning starts to gives a summary of the principle in fundamental working of the screwed respectively the Laser welded plate heat exchanger (PHE).
After having discussed the advantages of the PHE in comparison to other types of heat exchanger, the special adaptations for using applications of the PHE in the commercial and industrial refrigeration will be described.
Then the authors will mention the facts which have to be considered at the material selection depending on the purpose of the PHE within the refrigeration circuit.
The lecture will be focused on the description and valuation of the used PHE as a flooded or DX evaporator under consideration of its particularities and its limits of application.
The use of the module welded PHE as a DX evaporator within NH3 circuits of higher heat loads will be reflected closely. The whole lecture is based on our own investigations as well as practical experiences.
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ON THE DESIGN OF VERTICAL RISERS FROM AMMONIA
RECIRCULATION TYPE EVAPORATORS
H. T. HAUKAS
Consulting engineer, Lingavegen 225,
N-5630 Strandebarm, Norway
Fax: +4756559402 e-mail: hthaukas@2i.net

Design criteria for vertical risers carrying two-phase ammonia flow include minimized pressure drop at stable flow conditions and prevention of flow and pressure oscillations, particularly at re-duced load. Estimates for optimum vapour velocities with respect to pressure drop in vertical up-ward two-phase flow are available. A method to calculate the magnitude of the vertical pressure gradient is proposed. While these velocities may serve as design criterion for high riser systems (e.g. 4-5 m) at moderate evaporation temperatures, lower velocities should be applied in low tem-perature systems with less riser heights, due to greater relative significance of the other pressure drop components in the riser system.
At low and moderate vapour velocities, the liquid transport in vertical risers will be intermittent and, under certain circumstances, cause flow and pressure pulsations. This may become a major problem when pulsations in riser and evaporator interact and exacerbate instability, possibly bring-ing the entire sub-system into heavy oscillations. Annular flow in the riser will minimize the risk of oscillations and the requisite conditions to achieve annular flow are discussed.
At optimum vapour velocities, the flow will be well within the annular flow regime in most cases, with low risk of flow oscillations. For evaporators working over a wide capacity range, double ris-ers should be applied to keep vapour velocity above the lower limit for annular flow.
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The Design of a Test Rig to Measure the Internal Boiling Heat Transfer Coefficient
and Pressure Drop for Ammonia in a Horizontal Tube and also Pressure Drop
in 1800 Return Bends at Low Heat Fluxes
Cotter D J(a), Missenden J F(b), Nasralla M(c), Maidment G(b)
(a)Star Refrigeration Ltd, Derby, UK, Wincanton Close, Ascot Drive, DE24 8NB, UK
(b) London South Bank University, London, UK,
(c) Alfa Laval, Camberley, UK,.
Fax: +44-1332 –757289, e-mail: dcotter@star-ref.co.uk

It has been identified in a previous paper (Cotter and Missenden, 2004), that there is a lack of knowledge about the calculation of the internal heat transfer coefficient for ammonia boiling in the tubes of an ammonia air cooler. Zurcher et al (1999) found by measurement that this internal heat transfer coefficient ranged from 5 to 58 kW/m2K, for mass fluxes of 20-140 kg/m2s. A wide scatter of results existed at the lower heat fluxes and vapour fractions. In ammonia air coolers the internal boiling heat transfer coefficients had low heat fluxes of up to 2.5 kW/m2 with mass fluxes ranging from 19-70 kg/m2s. Test rigs to date have only been capable of measuring accurately the higher heat fluxes of 8 kW/m2 and above with low vapour fractions.
This paper outlines the design principles and calculated accuracies of an ammonia test rig that is being built to measure the internal heat transfer coefficient of ammonia boiling in plain horizontal tubes. It will be capable of measuring low heat fluxes 1.5-2.5 kW/m2 with mass fluxes ranging from 15-80 kg/m2s. The test rig has a second test section that is designed for measuring pressure drop in 1800 return bends. This part of the test rig also allows for flow visualisation of boiling ammonia.
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CARBON DIOXIDE AS REFRIGERANT: WHY, AND WHEN BENEFICIAL
Gert J. Koster (M.Sc.)
Grasso International B.V.
P.O. Box 343, 5201 AH s-Hertogenbosch,
The Netherlands
Fax: +31 (0)73 6203960, e-mail: gkoster@grasso.nl

Based on the Protocol of Montreal and later the Kyoto Protocol, increasingly sharper legislation on synthetic refrigerants made that alternatives have been developed and that techniques from almost a century old are reviving.
On the other hand, the natural refrigerant ammonia is also subject to increased legislative restrictions because of its hazardous effects to humans at reasonably low concentrations in air. For all refrigerants it applies that it is strived for reduced refrigerant content. So far, this is mainly achieved by applying secondary refrigerants like water, glycols, brine and other substances for the transport of the cold generated. From an energy consumption point of view, the energy consumption of these systems is 15 to 30 % higher than systems where the primary refrigerant also is used for the transport of the cold generated.
Application of CO2 as primary or secondary refrigerant also causes an increased energy consumption compared to an all ammonia system, but for a well designed system, the increase is limited to 5 to 10 %.
Based on studies and practical experience, it is shown and demonstrated (by calculation) under what circumstances CO2 as primary refrigerant in a cascade system with preferably ammonia, and when CO2 as secondary refrigerant can be applied with the lowest operational costs, including costs for defrosting of aircoolers, if needed.
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CO2 USED AS LOW TEMPERATURE REFRIGERANT IN AMMONIA-CO2 CASCADE SYSTEMS
N. P. Vestergaard
Danfoss Industrial Refrigeration A/S, Stormosevej 10, DK-8361 Hasselager, Denmark
Telephone: +45 87 38 96 19
E-mail: npv.dkacd@danfoss.com

The refrigeration industry is facing many new challenges. The global environmental threats, such as the ozone depletion, global warming and the green house effect, are all challenges that the refrigeration industry is facing. CFC, HCFC and HFC are all synthetic refrigerants, which are affected by the international agreement laid down in the Montreal Protocol, and later on the Kyoto Protocol to reduce these environmental threats.
Ammonia is a natural substance, not affected by these restrictions. It is a well-proven and effective refrigerant with more than 100 years of experience, and within industrial refrigeration it is the most dominant refrigerant. Even if it is well-proven and effective, there are still applications where it is difficult to use due to its toxicity or less effectiveness at low temperatures.
In a number of countries, in particular in Europe, it has become more difficult to install refrigeration systems with large ammonia charges, due to safety reasons. This together with the doubts about continuous availability of the halocarbon refrigerants has led to a renewed interest in CO2 (carbon dioxide).
This paper will focus on CO2 used as refrigerant in sub critical industrial cascade systems, and how CO2’s unique properties affect the design and maintenance of these systems.
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AMMONIA REFRIGERATION SYSTEM WITH CO2 AS A SECONDARY REFRIGERANT
M. Ono, K. Kawamura , N. Mugabi
Mayekawa Mfg. Co.Ltd., 2000 Tatsuzawa,
Moriya, Ibaraki, 302-0118, Japan.
Fax: +81-297-48-5170, e-mail: mn-nelson@mayekawa.co.jp

Ammonia is one of the oldest refrigerants in industrial use today. It is a natural refrigerant with excellent thermal properties. Most ammonia refrigeration systems, however, are of indirect type using secondary refrigerants. This is because of the flammable and toxic nature of ammonia. Most of the secondary refrigerants have poor heat transfer characteristics and high pressure losses at low temperatures thus offering low system COPs.
Carbon dioxide is being promoted as a secondary refrigerant. This is because carbon dioxide is a natural refrigerant (ODP=0, GWP=1), non toxic, inflammable and has good transport properties which results in low pressure losses in the pipes. The COP of the system, therefore, can be improved.
The system is easy to maintain since it does not require secondary refrigerant concentration, PH and corrosion control.
This paper reports on the development of an ammonia refrigeration system using carbon dioxide as a secondary refrigerant. The system was applied in a storage room and test results are reported.
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COLD STORAGE WAREHOUSE, USING DIRECT EXPANSION AMMONIA REFRIGERANT
Ray Clarke
ISECO Consulting Services Pty Ltd
723 Burwood Road, 3123 Hawthorn East, Australia
Fax: +61 3 9882 7339, ray@iseco.com.au

This paper presents the design approach adopted for the expansion of a large existing cold storage complex served by a liquid recirculation ammonia refrigeration system. The expansion required the addition of new rooms equivalent to 130% of the volume of existing rooms, as well as providing a means where by the new rooms could be independently operated for either frozen or chilled product storage duty.
Project Description: The completed complex comprised a total of two existing and three new –25oC freezer storage rooms (approx 230,000m3) and an associated +4oC stock transfer annex (approx 58,500m3). The ammonia refrigeration plant capacity is 1700 kW low stage and 2500 kW high stage.
Project Expansion: Three new 43,000m3 freezer rooms were added, each serviced by two, direct expansion ammonia, air-cooling evaporators. Each is arranged for automatic ambient air defrosting.
Innovation: - The design encompasses the use of supply air duct systems with jet air diffusers; which enables the ammonia evaporators located in alcoves, to be isolated from the stored product in the room. The design had to allow each of the three rooms in the new extension to operate independently for either chilled storage +2oC or freezer storage –25oC duty. The objective of the design was to incorporate a direct expansion ammonia system, self draining oil return and ambient air defrosting.
Refrigerant Piping: For chilled product duty either half of the evaporator capacity is switched off or all evaporators operate at lower temperature differences and fan speed, depending on the room usage plan. The room then operates via the high stage compressors, providing economical energy utilization. A common sub-cooled high pressure liquid feed supplies the evaporators, sseparate dry suction piping for chilled and freezer duty return to the compressors via a suction traps located in the plant room.
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THE PAST AND PRESENT OF AMMONIA REFRIGERATING SYSTEMS IN BULGARIA
S. Ditchev, N. Angelov, H. Nikolov
University of food Technologies, 26 Maritsa Blvd., Plovdiv 4002, Bulgaria
Fax: +359 32 642 841; e-mail: sditchev@mail.bg

The paper presents a short histological reference for the ammonia refrigerating systems in Bulgaria, the new tendencies for reconstruction and building of new industrial systems, and also some energy efficient and operation project concepts of industrial ammonia refrigerating units. The main sources of non-reversible losses in ammonia refrigerating systems have been discussed.
The data presented in the paper confirm the indisputable position of ammonia refrigerating systems for the future as well.
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AMMONIA REFRIGERATION INDUSTRY IN TURKEY
Y. O. DEVRES(a), C. YILMAZ(b)
(a)Istanbul Technical University, Food Engineering Department
34469 Maslak-Istanbul / Turkey
Fax: +90 212 285 29 25, email: onur@devres.net
(b)Frigo Sogutma Sanayi ve Ticaret A. S.
Mumhane Caddesi No:61, Karakoy-Istanbul / Turkey
Fax: +90 212 293 37 72, email: cyilmaz@frigo.info

Ammonia as a working fluid in refrigeration systems is widely used in Turkey in cold stores, food processing plants and other applications. The origin of the industry bases on foreign companies established in Turkey. The pioneer technicians and engineers started to work in such foreign companies and then on established their own businesses. Since then, like a chain reaction, numerous companies are founded but only a few of them are survived. Today most of the companies are Turkish. Compressors and process control equipments are being imported, evaporators, condensers, cooling towers and heat exchangers are being built in Turkey and they are being assembled according to design parameters. In universities, education of proposed refrigeration engineers is fulfilled in Mechanical Engineering Departments’ special sections of heat processing. Education of technicians in the field is being handled by Technical or Vocational High Schools or apprenticeship in plant-training. In this study, current situation and structure of Turkish ammonia refrigeration industry is described, constraints of industry are discussed, applications in various industries are mentioned, renewal and improvement requirements of plants in Turkey are evaluated and steps in installation of an ammonia refrigeration system are outlined respect to design measures, time schedule, cash flow and etc.
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DEVELOPMENT AND DEMONSTRATION OF AN INNOVATIVE INTEGRATED
REFRIGERATION AND HVAC SYSTEM IN A RECREATIONAL COMPLEX ICE RINK
M. Poirier(1), G. Pajani(1), D. Giguere(1), W. Dilk(2)
(1) CANMET Energy Technology Centre – Varennes, Natural Resources Canada,
1615 Lionel-Boulet, P.O. Box 4800, Varennes, QC, J3X 1S6, Canada
(2) CIMCO Refrigeration, Division of Toromont Industries Ltd.,
5909 – 83rd Street, Edmonton, AB, T6E 4Y3, Canada
Fax: + 1-450-652-5177, e-mail: georgi.pajani@rncan.gc.ca

CANMET Energy Technology Centre – Varennes and CIMCO Refrigeration (a Canadian manufacturer) are collaborating on the demonstration of an innovative system for recreational complex ice rinks in Canada, which main objective is to reduce the total energy consumption as well as refrigerant charge and leaks by approximately 50%. This in turn will decrease greenhouse gas (GHG) emissions of these buildings by about 50%.
Strategies to reduce energy consumption and GHG emissions of these buildings include the recovery of 100% of the energy rejected at the condensers of the refrigeration system, the integration of the refrigeration system with the heating, ventilation, and air-conditioning system (HVAC), and the adaptation of the refrigeration system to obtain maximum benefits from Canadian climatic conditions by continuously adjusting the condensing temperature to minimize building energy consumption.
The comparison of the new system with the current Refrigeration and HVAC systems led to an expected reduction of GHG emissions of 76 000 ton CO2-e in year 2012 in Canada, assuming a penetration in 50% of the new installations.
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AMMONIA HEAT PUMP FOR ENERGY SAVING IN FOOD INDUSTRIAL PROCESSES:
THE CASE OF A CHEESE FACTORY
G. PANNO(*), S. AUGUANNO, A. MESSINEO, D. PANNO
Department of Energy and Environmental Researches (D.R.E.AM.),
University of Palermo, Viale delle Scienze, Palermo 90128, Italy.
Tel. (+39) 091 236129, fax: (+39) 091 484425, e-mail: panno@unipa.it

In the last few years, the consumption of energy has been the heart of many papers about future developments of refrigerating engines. The studies regard especially refrigerating systems used in industrial fields, where their operation can cause direct and indirect effects on our environment. In order to set a limit to the harms induced by the use of synthetic refrigerants and in order to follow up energy saving, it is very important to investigate new solutions. This paper reports a feasibility study on the plants of a cheese factory by means of addition of an heat pump with ammonia as refrigerant in order to recover the termic reject of two refrigerating units and to supply the required heat to pasteurize the milk. It was computed, for the new lay-out, the energy saving and the reduction of emissions of CO2 compared to previous lay-out. The results obtained demonstrate that the proposed solution enables energy saving and advantageous effects on our environment.
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CHARACTERISTICS OF THE AMMONIA TURBOCOMPRESSORS AND
POSSIBILITIES FOR APPLICATION IN THE REFRIGERATING SYSTEMS
M. SAREVSKI, I. CEREPNALKOVSKI
University “Sv. Kiril & Metodij”, Faculty of Mechanical Engineering
1000 Skopje, Karpos II b.b. P.fah.464, Macedonia
Fax: +389 2 3099 298, e-mail: milan@mf.ukim.edu.mk

The main geometrical parameters and operating characteristics of the ammonia turbocompressors are analysed. The interdependence between the centrifugal compressor stage pressure ratio, peripheral speed, Mach number, compressor capacity, impeller diameter and width, speed of rotation and ammonia thermodynamic properties are shown and discussed for various refrigerating system operating conditions. The flow phenomena in ammonia centrifugal stage flow field with high pressure ratio and high Mach number are analysed. Due to small molecular mass of the ammonia, the centrifugal stage can attain relatively low pressure ratio in conditions of high impeller peripheral speed. Therefore, the ammonia refrigerating turbocompressors are multi stage ones. An approximated predictive method for the performance characteristics of the ammonia centrifugal compressor is presented. The possibilities for application of the turbocompressors in the ammonia refrigerating systems are discussed.
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DUAL-ENERGY HEAT RECOVERY SYSTEMS USING AMMONIA/WATER MIXTURES
V. MINEA(a), F. CHIRIAC(b)
(a)Hydro-Quebec Research Institute (LTE Laboratory), 600, de la Montagne, Shawinigan, Canada
(b)University of Civil Engineering, 66, Protopopescu, Bucharest, Romania
Fax: 1-819-539-1409, e-mail: minea.vasile@lte.ireq.ca

An ammonia-water mixture can be used as an efficient working fluid in industrial-type heat recovery heat pumps and heat transformers. Several configurations of such systems are possible depending on the availability of the waste (thermal) and primary (thermal or electrical) energy sources. This paper presents a portion of both authors’ old experience in the development, design and industrial demonstration of medium-temperature ammonia/water-based, dual-energy heat recovery systems for domestic or process hot water (compression/re-sorption) and intermittent or continuous ice production (two-stage absorption). Firstly, by using reciprocating dry ammonia compressors, an industrial pilot was developed in order to produce and supply hot water to a large residential district. The system configuration, as well as the main thermodynamic and hydraulic parameters, and specific operating experiences are presented. Secondly, using medium-temperature hot water prepared with parabolic solar collectors as a main primary energy source, a two-stage, industrial-scale absorption system for ice production was built and tested in a typical temperate climate. The main characteristics of the system, refrigeration circuits and operating modes are succinctly described.
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AMMONIA ABSORPTION CHILLERS IN DISTRICT COOLING SYSTEMS
B. CERKVENIK, D. ZIHER, A. POREDOS
University of Ljubljana, Faculty of Mechanical Engineering
Askerceva 6, 1000 Ljubljana, Slovenia
Tel.: ++38614771418, e-mail: bostjan.cerkvenik@fs.uni-lj.si

In the past years district cooling systems are getting more and more on attention. The cooling devices, usually vapor compressor chillers, are part of the district cooling system. They produce the cooling energy, which is then on a demand distributed over the district network. In several cases the absorption chillers with the working pair lithium bromide - water are used also, depending on the cost and operation analysis of the system. Their limitation is the operation above the freezing point of water, which does not allow us to store cold in a common way, in a form of ice.
In this paper the analysis of the use of ammonia absorption cooling devices in district cooling systems will be presented. The comparison between the H2O-LiBr and NH3-H2O absorption devices, as a part of a district energy system, will be made. Especially the possibility to use ammonia absorption devices over the night to storage cooling energy will be analyzed and discussed. With this advantage is their use, if compared to H2O-LiBr absorption devices, in several situations more interesting and legitimate.
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AMMONIA/DIMETHYL ETHER (R723) AS A NEW REFRIGERANT BLEND
D. KRAUSS(a), J. SCHENK(b)
(a) Schick + Co.,
Wernerstr. 28, D-70469 Stuttgart, Germany
Fax +49/711-81 491 13, e-mail SchickStuttgart@aol.com
(b)ILK Institut fur Luft- und Kaltetechnik gGmbH,
Bertolt-Brecht-Allee 20, D-01309Dresden, Germany
Fax +49/351-4081-250, e-mail werkstoffe@ilkdresden.de

The refrigerant R723 is made up of 60 mass% ammonia and 40 mass% dimethyl ether, it is environmentally-friendly (zero ODP, insignificant GWP). R723 is used in refrigeration systems as a working fluid in a similar way to R717. The pressure is almost identical but R723 has a number of interesting advantages over pure ammonia. With R723 the discharge temperature can be reduced by approximately 20 – 25 K. The solubility for mineral oils is considerably improved and can be extended the area of very low temperatures.
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THERMODYNAMIC ANALYSIS OF OPTIMUM CONDENSING TEMPERATURE OF
CASCADE-CONDENSER FOR CO2/NH3 CASCADE REFRIGERATION SYSTEMS
Tzong-Shing Lee(a), Cheng-Hao Liu(b), Tung-Wei Chen(b)
(a) Department of Air-Conditioning and Refrigeration Engineering
National Taipei University of Technology
No.1, Sec.3, Chung-Hsiao E. Rd.
Taipei 106, Taiwan
Fax: +886-2-87733713, e-mail: tslee@ntut.edu.tw

This study thermodynamically analyzed a cascade refrigeration system utilizing carbon dioxide and ammonia as refrigerants, to find the optimum condensing temperature of the cascade-condenser in which the system attained the maximum COP and the minimum exergy destruction. The results indicate that the optimum condensing temperature of the cascade condenser is -18?C under the condensing temperature of 35?C and the evaporating temperature of -50?C. The analytical results of this study are useful for the design and development of CO2/NH3 cascade refrigeration systems and related equipment.
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PERFORMANCES OF THE COMPRESSOR REFRIGERATING MACHINES WITH TWO-PHASE EJECTORS
M. SAREVSKI(a), V. SAREVSKI(b), V. SAREVSKA(b)
(a) University “Sv. Kiril & Metodij”, Faculty of Mechanical Engineering
1000 Skopje, Karpos II b.b. P.fah.464, Macedonia
(b) MZT IRI Enginering, 1000 Skopje, Pero Nakov b.b., Macedonia
Fax: +389 2 3099 298, e-mail: milan@mf.ukim.edu.mk

A new concept of energy recovery in the compressor refrigerating machines is presented, in which two-phase ejector device is introduced. Energy recovery of the high pressure and high temperature liquid refrigerant is achieved in the two-phase ejector, and the energy is used for pre-compressing of the vapor refrigerant existing the evaporator, before the compressor.
An analysis of the thermodynamic and gasdynamic parameters and performance characteristics of the ejector device, as well as innovated thermal system is realised using the calculating and optimizing procedures presented in the paper. The degree of improvement of the refrigerating machines efficiency depends on their design and operating conditions as well as on the thermodynamic properties of the refrigerant. The characteristics of the ammonia refrigerating cycle with two-phase ejector are analysed.