ABSTRACTS

AMMONIA REFRIGERATION RISK ASSESSMENT, PROBABILITY AND FREQUENCY
Anders Lindborg
Ammonia Partnership AB, Nyponv. 24, 260 40 Viken, Sweden.

The incidence of accidents and fatalities involving ammonia refrigeration is extraordinarily low compared to other risks in society. There is a general unawareness of this, with society pronouncing ammonia, with its heavy, pungent smell, as both dangerous and frightening. This paper explains why ammonia far exceeds its reputation. When designers and users of ammonia for refrigeration, heat pumps and ORC processes consider all safety codes, standard and legal regulations they conclude that ammonia is a safe and profitable refrigerant.
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MODERNIZATION OF AMMONIA REFRIGERATING SYSTEMS IN VIEW OF RELIABILITY, SAFETY, ENERGY CONSUMPTION AND ENVIRONMENTAL ISSUES
Gert J. Koster
Grasso International B.V.,
‘s-Hertogenbosch, The Netherlands

The recent developments in the world economy made me re-think about modernization of ammonia refrigerating systems. Most modernization requires investments at moments that the production is not growing. At the same time we can choose to upgrade an installation in view of efficiency and safety with limited costs. For that reason a more actual view is given on what can be done to increase efficiency, reliability and safety of existing refrigerating plants.
Although the issue efficiency very much is related to the basic design of the plant, it also is very much influenced by maintenance of the installation.
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LOW CHARGE CHILLERS BASED ON MICROCHANNEL HXs: OPPORTUNITY FOR EXPANDING USE OF AMMONIA
Pega Hrnjak
Professor and Co-Director, Air Conditioning and Refrigeration Center,
University of Illinois, Urbana Champaign,
President, Creative Thermal Solutions

This article discusses the charge reduction options in ammonia systems in general and in smaller, low charge chillers in particular. The focus is on charge reduction in heat exchangers, especially microchannel, but information is provided about new development in compressor technologies, specifically, the first hermetic scroll compressor. Data for void fraction of ammonia flow in microchannels is presented along with the data for an air cooled condenser and system. This paper also presents the excellent opportunities of using ammonia compared to other refrigerants in microchannels.
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MAKING THE CASE FOR HEAT PUMPS WITH AMMONIA AND CARBON DIOXIDE
Andy Pearson
Star Refrigeration Ltd.,
Thornliebank, Glasgow, G46 8JW, UK

The use of a Perkins cycle device to raise the quality of available heat in order to increase its value is almost as old as the cycle itself. This paper explains the different ways in which such devices are configured and sets out the reasons why they are gaining increased attention at the moment. The particular opportunities offered by the unusual properties of ammonia and carbon dioxide are explored and the prospects for the long term adoption of this technology are considered.
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SEMI HERMETIC AND HERMETIC AMMONIA COMPRESSOR PACKAGES
Nelson Mugabi
Mayekawa Mfg. Co.Ltd.,
2000 Tatsuzawa, Moriya, Ibaraki, 302-0118, Japan.

Not only environmental concerns that make ammonia, one of the oldest refrigerants in industrial use so attractive among old and new users, its excellent thermal properties also enables design and installation of systems with high COPs as compared to HFCs. The main disadvantage of ammonia, however, is toxicity, smell and flammability. For this reason, most ammonia refrigeration systems are of indirect type using secondary refrigerants.
There is, therefore, a need for systems with reduced refrigerant charge in order to increase safety and reliability of ammonia refrigeration systems. Miscible oil, compact heat exchangers, electronic expansion valves and semi hermetic compressors have been developed and as a result systems with drastically reduced refrigerant charge have been introduced into the market.
This paper reports on the development of semi hermetic ammonia compressor packages coupled with interior permanent magnet motors.
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2010-2020: A NEW DECADE OF CHANGES IN REFRIGERATION AND A/C,
VARIOUS APPROACHES TO ACHIEVING A LOW CLIMATE IMPACT
Lambert Kuijpers
Technische Universiteit, Eindhoven, NL
Co-chair UNEP Technology and Economic Assessment Panel
Co-chair UNEP TOC Refrigeration, AC and Heat Pumps
Lead Author IPCC WG III Fourth Assessment Report

By the start of the new decade CFCs will have been phased out in all developing countries. The focus will then shift to avoiding the emissions of CFCs and halons from existing banks in equipment and from stockpiles; although the Montreal Protocol does not control emissions, policymakers have asked for analyses on the climate impacts of emissions from banks to be conducted in 2009. The coming decade will also result in HCFC phase-out. Where it is currently well underway in developed countries and will be completed over the next years, the phase-out will start in developing countries with an agreed management plan. Here it should result in at least 35% reduction from the 2009-2010 HCFC baseline by the year 2020. If available and applicable, substitution of HCFCs should preferably be to low GWP alternatives and policy has directed substitution plans to be subject to environmental considerations including climate; for the first time ever. All this will occur together with the necessary change from HFC-134a to low GWP alternatives in mobile AC in many countries starting in 2011. This regulation has already spurred the development of low GWP HFCs or HFOs (such as HFC-1234yf and -1234ze) and further developments can be expected for more refrigeration and AC sub-sectors. At the same time the reduction in consumption of HFCs as well as a reduction of their emissions will be discussed more generally under both the Montreal and the Kyoto Protocol, where the latter controls the emissions via the “Kyoto basket”. 2009 will be the year when this issue will be taken up; it could lead to unexpected outcomes by the end of 2009, at the time the Copenhagen Climate Conference will take place. In summary, a number of developments will be set in motion in the year 2009, which will give new impetus to the application of low GWP refrigerants, where natural refrigerants including ammonia will have to play a role. This paper will give an overview of the interlinkages of the issues at stake and will attempt to give an outlook for future developments.
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AMMONIA SAFETY BY DESIGN AND MAINTENANCE
Alexander C. Pachai
Johnson Controls Denmark,
Christian X’s Vej 201, 8270 Hoejbjerg, Denmark

In recent years the awareness about safety has increased for many reasons. This had lead to a lot of discussions on how to increase the safety. It all starts with design followed by good practice during installation followed by careful maintenance. There are obligations to be understood by both the contract but also by the user and owner of the system. Standards do not always fully meet all requirements and you can say that just fulfilling what standards and laws say is not always good enough.
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THE SEPARATE AND COMBINED USE OF AMMONIA AND CARBON DIOXIDE IN REFRIGERATION SYSTEMS,
PART 1: AMMONIA AND CO2/NH3 CASCADE SYSTEMS
Klaas Visser
KAV Consulting Pty Ltd,
PO Box 1146, Kangaroo Flat Vic 3555 Australia

Ammonia refrigeration systems are widely used in many primary industrial food processing industries like livestock conversion plants, fish and coffee processing facilities, vegetable freezing plants, malting plants and breweries, ice cream plants, etc.
Ammonia with its excellent thermodynamic and physical properties has enjoyed a continuous use now for almost one and a half centuries and popularity has not been materially effected by the advent of the CFC’s in the early 1930’s, soon to be followed by HCFC’s.
CO2 on the other hand, was a popular refrigerant for about 60 years from the 1870’s onward, but its decline started with the arrival of CFC’s. Svariegaard (1996) showed that the last CO2 plants were built for mainly marine applications around the late 1950’s. See Figure 1.
In this paper evidence is presented that two stage ammonia refrigeration systems applied to industrial freezing and cold storage facilities are more energy efficient than CO2/NH3 cascade systems at evaporating temperatures of about –380C and higher. Below about –380C evaporating temperature CO2/NH3 cascade refrigeration systems for the same duty are more energy efficient.
It is also shown, that in the case of two stage refrigeration plants with significant high stage and AC cooling loads being serviced from the same control plant, a CO2/NH3 cascade system with DX CO2 for chilling and AC cooling loads is about 5% more energy efficient than a two stage ammonia system using glycol as a secondary refrigerant.
The use of Ammonia heat pumps as a third stage added to a two stage ammonia plant or CO2 ammonia cascade system is discussed and calculated performance figures are presented.

PART 2: SUB– AND TRANSCRITICAL CO2 SYSTEMS
Klaas Visser
KAV Consulting Pty Ltd,
PO Box 1146, Kangaroo Flat Vic 3555 Australia

Carbon Dioxide was widely used in all manner of refrigeration systems for cooling, chilling and freezing for about 60 years from the mid 1870’s onward, but its decline started with the arrival of CFC’s in the 1930’s.
In this paper, it is shown that carbon dioxide used as a refrigerant in both office and hospital air conditioning cooling and heating, and industrial refrigeration applications offers the potential to save considerable amounts of energy when used as a standard refrigerant in a system capable of running in both subcritical and transcritical mode, and attendant CO2 emissions and cooling water.
The high pressure and low critical point characteristics allow CO2 to be used in the sub-critical mode at a low condensing temperatures within 3 to 50C of the ambient air used for condenser cooling. Above the low critical point of 31.1 (73.83 bara) transcritical operation is a distinct advantage, as it becomes possible to extract heat at a gliding temperature from the transcritical compressor discharge. In many applications where simultaneous heating and cooling is part of the process, cooling and a lot of heating may be extracted from the same source. This reduces energy and cooling water consumption and attendant CO2 emissions. There are also some capital cost offsets.
Using USA department of Energy and Australian Greenhouse Office data for energy consumption for buildings in the USA and Australia, this study shows that CO2 cooling has the potential to reduce primary energy consumption, combined cooling water consumption at the power stations and cooled buildings, and CO2 greenhouse gas emissions by about 40 to 50%, 40 to 50% and 45% to 55% respectively in the existing building stock when coupled with a 25% reduction in duct air velocity and greater savings when implemented in new buildings. Incorporation of energy recovery from exhaust air and economizing cycles will produce additional reductions in all areas. The absence of cooling towers entirely eliminates the danger of legionella disease and because CO2 is used as a refrigerant, there is no chance of HFC fugitive gases escaping into the environment.
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A NEW GENERATION OF AMMONIA UNIT COOLERS
S. Filippini, U. Merlo
LU-VE SpA, 21040 Uboldo, Varese, Italy

LUVE has recently carried out several tests on cooler behaviour with the aim of understanding frost formation better and improving product efficiency.
Traditionally, the main design criteria for NH3 coolers have been:
1. capacity
2. air flow
3. surface
4. fin spacing
5. cooler configuration (i.e. cubic, dual discharge, fast freezer, blow through, draw through,…)
Point 5 is normally linked to the type of application and is not the subject of this analysis.
The focus of LUVE R&D activity concentrated mainly on points 1 and 3. In fact for a certain capacity (and fin spacing) a minimum surface is very often specified. Is that the correct approach? We are not sure; in fact with a given minimum surface there is the intention to have a product which can have a certain performance during its real operating time (i.e. during frost formation).
However the cooler configuration (coil geometry, number of rows, fin shape, air velocity, proper combination of fan with coil…) are crucial parameters characterizing product performance; it is clear for example that a unit with too many rows may actually have poor performance during frosting, if the fan cannot ensure proper air quantity while operating.
Therefore our target was clear: EFFICIENCY!! That means making products which have the highest possible efficiency in real working conditions. Thanks to the use of Computational Fluid Dynamics Software and extensive testing in the LU-VE laboratory, a new generation of coil geometry was developed, aimed at performing well under frost formation with proper use of the finned surface. The surface has several turbulators for perfect aerodynamic configuration. Particular attention was paid to their definitions and a micro-photographic evaluation of frost formation on finned turbulators was made clearly showing frost growth on finned surface.
This paper describes in detail the CFD software analysis, test ring, testing activity and the results of this important development.
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SELECTING EVAPORATIVE CONDENSERS FOR OPTIMUM SYSTEM EFFICIENCY
Rob Vandenboer
Evapco Europe NV,
Industriezone Oost 4010, B-3700 Tongeren, Belgium

The cost and availability of energy has become a major issue for large power consumers all over the world. As a result of the change of pace in the power generation and distribution business and the threat of significantly higher costs, there is a greater emphasis on optimizing system efficiency in Air-Conditioning, Industrial Process and Industrial Refrigeration applications.
This paper will review the relationship between the compressor and evaporative condenser in an ammonia refrigeration system in terms of system operation and energy consumption. In addition, examples will be provided to demonstrate how system efficiency can be optimized by increasing the heat transfer surface area of the condenser and by developing the proper method of operating the condenser and compressor to reduce total energy consumption.
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PROPERTIES AND OTHER ASPECTS OF AQUEOUS AMMONIA SOLUTIONS FOR INDIRECT REFRIGERATION SYSTEMS
Ake Melinder
Dept. of Energy Technology, School of Industrial Engineering and Management
Royal Institute of Technology, KTH, S-10044 Stockholm, Sweden

Indirect systems with aqueous solution used as secondary working fluids (secondary refrigerants, brines) have long been used making it possible to minimize the charge and leakage of (primary) refrigerant. Only a few systems have in recent years been installed with aqueous solutions of ammonia although many are aware that ammonia – water has quite favorable thermophysical properties compared to other water solutions. Accurate thermo-physical property data and also a general knowledge of other secondary fluid properties are needed for choice of suitable concentration and for technical calculations of the system. An extensive research with the aim to establish reliable data for a number of aqueous solutions, incl. ammonia resulted in the IIR publication, Thermo-physical properties of liquid secondary refrigerants (Melinder, 1997). Figures show that few data were found for ammonia solutions for temperatures below 0°C except for the freezing point. Additional research to update and extend data for various fluid types and applications will result in a new publication entitled Properties of secondary working fluids for indirect systems intended to be published by IIR in 2009. Among fluid properties considered are freezing point and additive concentration, density, index of refraction, specific heat, thermal conductivity and viscosity. Polynomial equations and coefficients used in an Excel-program are an aid to determine property values and can be used for simple technical calculations. Other figures show computer program agreement with original table values and with some commercial product data. Other properties and aspects of the aqueous solutions used, such as boiling point, flash point, vapor pressure, surface tension, specific conductance and pH-value are considered. The new publication will cover corrosion and material compatibility in aqueous solution systems and environmental impact of such fluids, incl. direct toxicity and biodegradability. Hopefully this new publication will prove to be useful for industry and researchers working with ammonia - water in various applications.
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AMMONIA-WATER SOLUTION IN ICE RINKS. THE ULTIMATE BRINE?
Anders Bache, SB Kylteknik AB,. Skallakra, 430 22 Varobacka, Sweden
and
Claes Stenhede, Consultant to Alfa Laval, Via Trento 15, 37 124 Verona, Italy

This paper describes the conversion of the secondary cooling medium in an ice rink, from calcium chloride to an ammonia-water solution. The use of an ammonia-water solution, also called ammonium hydroxide or alkali, as a brine has been described elsewhere (Gibert, 2007). However, to the authors' knowledge, all previous cases have been green field installations. The present case involves an old, heavily polluted brine system and the paper reports the experience of this conversion.
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AMMONIA HEAT PUMP FOR DISTRICT HEATING AND COOLING OF AN ICE RINK
G. Eggen(a), T. Nilsen(b), O. Slettahjell(a), E. Steen(b), G. Svendsen(b)
(a) COWI AS, P.O.Box 2564 Sentrum, NO-7414 Trondheim, Norway
(b) Fosenkraft AS, P.O.Box B, NO-7159 Bjugn, Norway

In 2005, the local energy company Fosenkraft AS in Bjugn in Mid-Norway built a small district heating system for public and domestic buildings. A two stage ammonia heat pump with a heat capacity of 1 000 kW is the main energy plant, and sea water is the low temperature heat source for the heat pump. Since the head of the fjord at Bjugn is very shallow, the heat pump collects low temperature heat by means of brine that circulates through 20 km of plastic tubing buried in the seabed.
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APPLICATIONS OF schickR723® BLEND IN COMMERCIAL REFRIGERATION SYSTEMS
J. Germanus(a), S. Romer(a), D. Krauss(b)
(a) Institut fur Luft- und Kaltetechnik gGmbH, Bertolt-Brecht-Allee 20, Dresden, 01309, Germany
(b) Schick GmbH + Co. KG, Wernerstrasse 82, Stuttgart, 70469, Germany

The azeotropic blend of ammonia and dimethyl ether is an alternative to ammonia. The mixture of 60 weight% ammonia and 40 weight% dimethyl ether was designated schickR723® after the molecular weight, in accordance with the refrigerant nomenclature for inorganic refrigerants.
In comparison to pure ammonia, the blend has a lot of advantages. With the schickR723®, lower discharge temperatures of approximately 15-25 degrees are possible. The solubility of the refrigerant in conventional oils is improved. An additional characteristic of the blend is the higher heat transfer in evaporator and condenser.
The COP value of the blend is higher than the pure ammonia. Because of the low GWP value and a zero ODP value the blend is an environmentally friendly natural refrigerant.
The azeotropic refrigerant can be used in small and medium size refrigeration systems as a working fluid in a similar way to R717. Further applications of the refrigerant are provided.
The presentation shows several examples where schickR723® is used as working fluid under real working conditions with different components like compressors in refrigerating machines. The positive experiences demonstrate the advantage of the schickR723®.
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THE DEVELOPMENT OF AZEOTROPIC AMMONIA REFRIGERANT BLENDS FOR INDUSTRIAL PROCESS APPLICATIONS
N. Cox(a), V. Mazur(b), D. Colbourne(c)
(a) Earthcare Products Limited, 405 Mill Studio, Crane Mead, Ware, Herts. SG12 9PY, UK
(b) Department of Thermodynamics, Academy of Refrigeration, 1/3 Dvoryanskaya Street, 65082 Odessa, Ukraine
(c) Re-phridge, PO Box 4745, Stratford-upon-Avon Warwickshire CV37 1FE

It would be desirable to design an azeotropic ammonia mixture with higher pressure to avoid the disadvantages of pure ammonia. The objective is to determine the appropriate proportions for a mixture that would allow this blend to be employed for food blast freezing applications in the temperature range from - 55°C to + 50°C.
Ammonia has a high NBP and low specific heat. Low evaporating temperatures lead to sub-atmospheric operation allowing leakage of air into the system, and high compressor discharge temperatures. The selected blend overcomes these drawbacks by significantly reducing the NBP and allowing lower discharge temperatures. It will displace liquid nitrogen and carbon dioxide cryogenic freezers as well as carbon dioxide / ammonia cascade and two stage ammonia systems. The following findings were made relative to R717:
COP similar
Volumetric refrigerating effect (VRE) higher
Discharge temperature significantly lower, improving reliability
Improved heat transfer
Higher evaporating temperatures
Degradation of COP and refrigerating capacity with increasing temperature lift reduced
Patents have been filed and published and global licensees are now being sought.
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A DESIGN PROCEDURE FOR ENERGY EFFICIENT MEAT CARTON FREEZING SYSTEMS
Klaas Visser
KAV Consulting Pty Ltd,
PO Box 1146, Kangaroo Flat Vic 3555 Australia

Freezing is an attractive method of food presentation compared to other methods like salting, canning, drying, fermentation, irradiation, etc. Freezing also preserves more desirable attributes such as nutrition, taste, texture and shelf life than other methods in a relatively straight forward manner. However, freezing is a relatively costly exercise because of high purchase and operating costs. A design procedure to achieve minimum energy consumption when freezing cartons of meat is discussed by varying the time-temperature relationship. The freezing energy subsidy expressed as a percentage of nutritional energy preserved in the frozen food is given for frozen meat and some other foods at the primary production stage. It is demonstrated that an energy efficient freezer design does not necessarily require a higher capital investment and frequently less.
It is also shown that selection of the refrigeration compression plant on the basis of compressor COP is frequently poor practice in Air Blast Freezing Systems (ABFS). Rather, it is best practice to select equipment for the freezer operating conditions where the total energy input into the system is a minimum. Total energy inputs into the system are for boosters, high stage compressors, air circulating fan, liquid refrigerant pumps and some other loads like refrigerant condensers and/or cooling towers and cooling water pumps.
It is recommended that the sum of the energy consumption of the air circulating fans plus the compressor energy to remove the heat generated by the fans, does not exceed 15%.
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CHARACTERISTICS OF THE HEAT-EXCHANGE APPARATUSES OF THE CASCADE REFRIGERATION MACHINE, OPERATING ON AMMONIA, NON-AZEOTROPIC MIXTURE
Kudrat Karimov
Tashkent State Technical University,
University st., 2, 100095, Tashkent, Uzbekistan

The purpose of this theoretical investigation is comparison heat-exchange apparatuses of the cascade refrigeration machine. Heat-exchange apparatuses – condenser of the high stage and condenser-evaporator are made from bare-pipe (1-st variant of apparatuses) and pipe with transverse ring swirl strips (2-nd variant). Comparison is made at operating conditions of R170 – R290/R600a/R600 and R13 – R717 systems.
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EUROPEAN SAFETY STANDARD EN 378-2008 IN COMBINATION WITH THE GERMAN NATIONAL STANDARD VDMA 24020-1 – OPERATING REQUIREMENTS ON AMMONIA REFRIGERATION SYSTEMS
B. Schrempf
TUV SUD
80339 Munich, Germany

The new edition of the standard EN 378 – Refrigerating systems and heat pumps – Safety and environmental requirements now regulated the safety efforts for refrigerating systems with the refrigerant ammonia. This safety-standard is not only using in Europe – this standard is using in many further countries in the world. So, also for ammonia-refrigeration systems is existing an
European harmonized Standard and only for Europe.
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AMMONIA REFRIGERATION SAFETY MANAGEMENT
Mark Roxburgh
Mercury Technologies Ltd.,
Hopps Cottage, Front Street, Hart, United Kingdom, TS27 3AJ

Ammonia as a refrigerant is an obvious choice in these times of ecological awareness. It is a natural substance and its thermodynamic properties are superior to many of the man-made alternatives. However, its hazardous nature must not be overlooked. End-users are legally and morally obliged to ensure that they have in place safety management sufficient to mitigate the risk associated with their ammonia refrigeration systems. The programme described herein outlines a number of safety management tools that will allow the risk level to be reduced to as low as is reasonably practical.
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THE USE OF STRAIN GAUGE STRESS MONITORING SYSTEMS ON AMMONIA REFRIGERATION PIPEWORK AFFECTED BY UNDERGROUND MINING SURFACE SUBSIDENCE
Jonathan E Fryer
ISECO Consulting Services Pty Ltd
723 Burwood Road, Hawthorn East, Victoria 3123 Australia

In 2008, an underground long wall coal mine was drilled approximately 200meters deep under part of an exiting turkey processing facility which uses ammonia refrigeration piping systems for process cooling and cold storage. To minimize the risk of pipe work failure due to stress induced by ground subsidence, the pipe work at this site was replaced before the mining commenced. The replacement piping design was modelled using the Whesso Pipe Stress Analysis software PSA 5 and for selected sections of piping additional pipe support displacements (to simulate ground subsidence) were added to the model. This was necessary to demonstrate compliance with The Australian Standard AS4041 –Pressure Piping.
Strain gauges were installed on 64 sections of pipe work identified as likely to experience high stress. A web based monitoring and alarm system was installed to provide early warning if predetermined trigger levels were exceeded.
The paper discusses why flexibility analysis should be carried out on ammonia refrigeration piping systems, compares the predicted stresses with actual measured stress at a number of piping locations, shows how remedial action reduced actual stresses and provides lessons learnt from strain gauge installation and monitoring at an industrial food processing facility.
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AMMONIA PLANT ENGINEERING AND CONSTRUCTION – SAFE HANDLING OF NH3 TO GUARANTEED MAXIMUM EFFICIENCY AND PLANT SAFETY
D. Krauss And M. Gehres
Schick GmbH + Co.KG,
Wernerstr. 82, D-70469 Stuttgart, Germany

A technical application for ammonia plants is for nitrogen case-hardening processes. For this technology ammonia is used as an indispensable operating fluid supplied to hardening furnaces for creating a protective atmosphere.
On one hand Ammonia is classified as a liquid that is hazardous to water and on the other hand ammonia is both poisonous and explosive under certain conditions. In regard to this fact according to ATEX (Reg. 94/9/EU) ammonia belongs to Ex-Zone 2. Our aim is to demonstrate to satisfy the highest degree of safety to support the mainly advantages of ammonia. We all know that the chemical substance ammonia is environmentally-friendly, along with this ammonia supply plants are put into practice according to a high engineering standard and take into strong consideration European and German guidelines.
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EU REFRIGERATION AND AIR CONDITIONING LEGISLATION IMPLEMENTATION IN ROMANIA - AMMONIA AS A VERY ECO-EFFICIENT REFRIGERANT ALTERNATIVE
Gratiela-Maria Tarlea
Technical University of Civil Engineering, Bd. Pache Protopopescu nr. 66, Bucharest, 021414, Romania
Vice President of the Romanian General Association of Refrigeration

This paper presents a study of the Romanian line up to the environment, refrigeration and air-conditioning EU legislation with the recommendation of using ammonia as a very eco-efficient alternative.
The establishment of a Code of Practice (CoP) in this field is part of the work presentation and a project implemented by UNIDO (The United Nation Industrial Development Organization) and one of the recognized actions required to reduce CFC, HCFC and HFC demand in the servicing sector in Romania and to introduce ammonia and other natural refrigerants as eco-efficient alternatives. Some activities above were done with the assistance from an international refrigeration consultant from the Stockholm Environment Institute (IC). ROMANIAN GENERAL ASSOCIATION FOR REFRIGERATION (AGFR) as a national consultant (NC) was responsible for requesting assistance of the IC and managing his time taking into consideration the limited time available by the IC for these activities. The NC (AGFR) worked in close collaboration with the Ministry of Environment and Sustainable Development (MESD), suppliers/distributors, and representatives from the trade and other relevant government agencies.

The NC (AGFR) ensured that the work was made in close collaboration with the MESD and that due consideration was made in particular with regard to the project to initiate infrastructure to reclaim refrigerants, the review of the legislation and other relevant legislation and the training program.
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DESIGN AND SIMULATION OF AN AMMONIA ABSORPTION CHILLER FOR THE PRECOOLING OF NATURAL GAS IN A SMALL-SCALE LIQUEFACTION PLANT
A. Arteconi, C. Brandoni, S. Colasanto, G. Santori
Universita Politecnica delle Marche – Dipartimento di Energetica,
via Brecce Bianche, 1 60131 Ancona

This paper describes an ammonia absorption chiller used to precool a natural gas stream to be liquefied. This application is referred to a novel small-scale LNG (Liquefied Natural Gas) plant, whose purpose is the liquefaction of small amounts of natural gas directly on site for the final user. In order to have the economic feasibility of a LNG small scale production, it is necessary to achieve the highest energy efficiency of the liquefaction process. For this purpose an ammonia refrigeration machine is used, powered by waste heat from exhaust gases of the I.C. engine that drives the LNG plant compressor. The absorption chiller uses water-ammonia as working pair and cools the compressed natural gas stream down to –30°C.
In the paper a simulation of the ammonia absorption chiller is performed for the abovementioned application, describing its operating conditions, energy efficiency and influence on the energy balance of the whole plant.
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POTENTIALS AND LIMITATIONS OF TRIGENERATION
Arnd Hilligweg
Nuremberg University of Applied Sciences, Faculty of Mechanical Engineering
Kesslerplatz 12, D-90489 Nuremberg, Germany

In a recent study Stockinger et. al. (2007) investigated combinations of IC-engine based combined heat and power plants with single stage absorption chillers. Here a graphical method is presented which helps to easily keep records of the components’ efficiencies as well as of the users’ demands.
Technically feasible plant designs and -as the case may be- additional external energy flows are pictured in respective areas of a newly introduced effective energy trigram, an equilateral triangle with axes showing the fractions of heat, power and cooling effect.
Applying the outlined strategy in discussions between consultant and contractor helps to get a realistic view on technical options. Furthermore the suggested method ensures that the cogeneration plant will operate on exergetically sound basis without overgeneration of any effective energy, thus resulting in an ecological and economically successful operating mode.
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AMMONIA-WATER CYCLES FOR ELECTRICAL POWER GENERATION
Vaslile Minea
Hydro-Quebec Research Institute, Laboratoire des technologies de l’energie – LTE
600, avenue de la Montagne, Shawinigan, G9N 7N5, Canada

The world’s energy consumption is projected to grow 70% and the energy-related carbon dioxide emissions, to rise by more than 40% from today to 2050. In this context, industrial waste heat and geothermal energy represent alternatives aiming at reducing primary energy consumption. This paper presents a short overview of thermodynamic cycles allowing converting industrial waste heat and deep geothermal energy in electricity. The thermal calculation of a basic ammonia-water power generation cycle shows that with heat sources at temperatures as low as 120°C, this working fluid mixture is able to achieve satisfactory efficiency. The future of ammonia as natural and efficient refrigerant seems more and more promising.
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AMMONIA-WATER ABSORPTION HEAT PUMPS WITH MEMBRANE ABSORBER
C. Ghiasi(a), M. C. Marti-Calatayud(a), T. Weimer(b), F. Ziegler(a)
(a) Institut fur Energietechnik, Technische Universitat Berlin, KT2, Marchstr. 18, D-10587 Berlin, Germany
(b) Makatec Apparate GmbH, Siemensstra?e 3, D-71149 Bondorf, Germany

Today, membrane technology plays an important role in water and waste water purification systems and also in medical applications like artificial lungs and dialysis equipment. In this paper we present a project in which we try to introduce the benefits of membrane technology on ammonia-water absorption chillers.
Some major components like absorber, desorber, and rectification column may be substituted by components that use membrane contactors. These membrane contactors are made by polymers that will be easier manufactured and cheaper in price than the conventional components in an absorption chiller.
In lab scale tests the performance of membrane absorbers will be compared to that of plate absorbers and with simulation results. In this paper the test rig is presented.
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FURTHER RESULTS IN AMMONIA/WATER COABSORBENT TECHNOLOGY DISTRICT TRIGENERATION
Mihail-Dan Staicovici
S.C. Varia Energia S.R.L. & S.C. Incorporate Power-Absorption Engineering S.R.L.,
str. Mihail Eminescu, nr. 81 B, 020 072 Bucuresti, Romania

Previous author papers analyze the coupling of thermal power plants (e.g. Steam (Organic) Rankine Cycle (S(O)RC), or Diesel engine type), with Coabsorbent Technology (CT) for district combined cooling, heating and power (CHP, i. e. Trigeneration) production. This work presents ammonia/water further research results thereof. First, district heating with coabsorbent heat pumps coupled to S(O)RC vs. S(O)RC cogeneration heating are comparatively assessed with a simple model. Unlike usual heat pumps, coabsorbent ones can perform better than heating in cogeneration, but feasibility studies must be done for each application. Second, S(O)RC-CT vs. S(O)RC-MVC (Mech. Vap. Compress.) CHP systems are evaluated with respect to electrical power output for same cooling and heating loads, within a large range of cooling (0 to -70?C) and heating (70 to 150 ?C). Coabsorbent candidates selection found nontruncated cooling fractal be best for cooling up to -35 ?C, with relative primary energy savings and comparative electrical efficiency of (23.9 – 26.6) % and , respectively. Cooling, up to -70 ?C, and air conditioning recommend truncated fractals and quadruple-effect fractals use, respectively. Improvements include operation with low- or non-volatile absorbent working combinations. Work results encourage S(O)RC-CT trigeneration R&D. Besides known applications, CO2 mitigation for clean energy, and district electrical power distribution net cooling, saving power and paving the way of future high-temperature superconductors large scale utilization, might be considered.
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PERFORMANCE OPTIMIZATION FOR THE RESORPTION HEAT PUMP WITH TWO USEFUL HEATING EFFECTS
S. Porneala, C. Iosifescu
“Dunarea de Jos” University of Galati,
111 Domneasca Street, 800201, Galati, Romania

This paper shows the advantages for using the ammonia-water solution in a resorption heat pump and the importance of optimizing both the COP and the exergetic efficiency as a function of boiling pressure. The most important heating effect is realized through heat recovery from the absorber and from the resorber in order to prepare hot water. A second heating effect is obtained through heat recovery from the vapor at the outlet of the vapor generator VG; this second effect is smaller in value, but the water temperature is higher. The system with two heating effects is characterized by higher values for the exergetic efficiency. This solution answers to some practical application where two temperature levels for the heat are required. The study was performed for different function conditions for the plant.
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HEATING LOAD OPTIMIZATION FOR THE ABSORBER OF AN ABSORPTION HEAT TRANSFORMER
C. Iosifescu, S. Porneala,
“Dunarea de Jos” University of Galati,
111 Domneasca Street, 800201, Galati, Romania

The paper presents a study of an absorption heat transformer, with the goal to maximize the absorber heating load. The description and the mathematical model of the system are included. Conclusion of the study is that there are certain temperature differences for each heat exchanger that lead to a maximal absorber heat load. The distribution of heat transfer surfaces between the heat exchangers (considering a fixed total heat transfer surface) also influences the absorber heating load.
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STUDY OF COOLING PRODUCTION WITH A COMBINED POWER AND COOLING THERMODYNAMIC CYCLE
V. Popa(a), L. Costiuc(b)
(a) “Dunarea de Jos”University of Galati, 111 Domneasca Str., Galati, 6200, ROMANIA
(b) “Transilvania”University of Brasov, Bdul Eroilor 29, Brasov, 500036, ROMANIA

This work is an investigation of a novel concept to produce power and cooling with the energy contained in low-temperature (< 200°C), thermal resources. These resources can be obtained from non-concentrating solar thermal energy, low-grade geothermal resources, and a near infinite variety of waste heat sources. The concept under investigation uses thermal energy in a low-temperature boiler to partially boil an ammonia-water working fluid mixture. This produces an ammonia rich vapor that drives an expander. The expander’s output is mechanical power; however, under certain operating conditions its exhaust can be cold enough to use for cooling. This possibility is the main objective of this work.
An analytical study is presented which identifies expander efficiency, expander inlet conditions, and exhaust pressure as the factors determining exhaust temperature. Estimated expander efficiencies are based on a consideration of the operating conditions and a review of current technology.
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