International Institute of Refrigeration
Ammonia Refrigeration Technology
International Conference
- Ohrid 2013 -


Making ammonia refrigeration plants safer
Andy Pearson

Star Refrigeration Ltd., Thornliebank, Glasgow, UK

The use of ammonia as a refrigerant introduces some significant hazards; toxicity, flammability, low temperatures and pressurised volatile liquid are the most obvious. It has an excellent safety record but there is undoubtedly still room for improvement. This paper reviews some anecdotes of ammonia incidents and accidents over the last twenty years and considers where the real danger came from. This is contrasted with the requirements of our existing safety codes, standards and regulations to establish whether there are any deficiencies in the current approach. Ways in which we could improve the safety record of ammonia are considered and a proposal for a new approach to refrigeration safety is outlined.

DX ammonia evaporators – flow regimes, charge and heat transfer
Predrag Hrnjak
University of Illinois (USA)

This article discusses the heat transfer and pressure drop in evaporation of ammonia. An example of an experiment with DX evaporator is presented. The evaporator was equipped with partially transparent tubes so that visualization of the flow regimes and estimation of the void fraction was done in real application, with actual oil present in the system. Visualization indicated flow regimes like at a bit lower mass flus than Zürcher at al. would predict but reasonably close. The flow is characterized with very high void fraction. These flow regime visualizations indicated that any mechanism that would spread liquid to the walls would be extremely beneficial.

Current and future trends in Ammonia refrigeration systems and control components
Niels Vestergaard

Danfoss (Denmark)

The global refrigeration industry has during several years been undergoing several changes. In particular the global environmental impact of some refrigerants, such as the ozone depletion, global warming and the greenhouse effect, has changed the industry considerable. The environmental impact is mainly focused on the synthetic refrigerants like CFC, HCFC, HFC and HFO.
Natural refrigerants, like Ammonia, Carbon Dioxide (CO2) and Hydro Carbons are not affected by environmental restrictions; however toxicity and flammability are issues that restrict the use of these refrigerants.
This paper will mainly focus on Industrial Refrigeration, and applications utilizing the natural refrigerants.

Past, present and future of ammonia as refrigerant, from a leading industrial end-user perspective
Rene van Gerwen

Unilever Engineering Services (Netherlands)

Unilever, being one of the largest fast moving consumer goods companies in the world, is one of the largest end-users of refrigeration throughout its supply chain. In view of Unilever’s Sustainable Living Plan, application of natural refrigerants is strongly encouraged. Ammonia is the preferred refrigerant in its manufacturing facilities.
Five value drivers called ’5C’, being ‘Core design, Carbon/costs, Cash, Capability & Compliance’ are defined and applied for continuous improvement of almost all processes in product manufacturing. A specific set of value drivers has been defined for ammonia refrigeration. These drivers provide an outlook for future trends, from an FMCG end-user perspective. Increased focus on standardisation, modularisation, sustainability, leveraging scale of business, competence of personnel and process safety standard compliance are identified as common trends.
In order to create a robust system across all the Unilever sites utilising ammonia refrigeration, these ‘5C’ value drivers form a consistent and integrated package attributing to value creation throughout the value chain. Global implementation of this package is structured through global and regional Communities of Practice.

Franc Kosi

University of Belgrade (Serbia)

The paper gives an overview of ammonia industrial refrigeration plants in Balkan countries. A brief chronology of the development of industrial refrigeration in the countries of the former Yugoslavia and current status of refrigeration equipment which has been dominating in the Balkan market for the last fifty years are presented. Based on personal insights of author acquired within many years of experience in the planning, designing and construction of industrial refrigeration installations, and including appropriate examples, the basic technical features of the relevant systems are given. In particular analyzed are the problems related to the renovation and reconstruction of existing ammonia installations, with special emphasis on the charging and the possibility of improving energy transformation of refrigeration systems. A short summary of suggestions for improving the existing status of ammonia refrigeration systems in the Balkan region is also stated.

Heat pumps and their economics
Alexander Pachai

JCI - Sabroe (Denmark)

Heat pumps have attracted a great deal of attention in different parts of the world. Energy prices are high, very high, at the moment and have been for quite a while. Energy prices have been high before, historically, but never this high and for as long as they have been over the past 5 years. This generates great pressure on production where heating and cooling make an essential part of the product price. Energy prices vary tremendously all over the world. It is therefore relevant to figure out the relationship between different price levels on electricity, oil and gas. This information can be gathered from different sources, but local high volume customers can get better prices than the ones stated in the tables available on the internet.
In the past, heat pumps were mainly used for domestic heating using different energy sources. The industrial market has many other sources than the domestic market. New products are becoming available for production of water at temperatures as high as 90°C. The Coefficient of Performance (COP) is high thus ensuring a high Return Of Investment (ROI). The price of energy is regulated in different ways in different countries. The challenge is to look at the system implementation and figure out how to get the most out of the heat pump and where it would make sense to use the technology.

Heat recovery in fish meal industry by high temperature hybrid heat pumps
Stein Nordtvedt

Institute for Energy Technology (Norway)

The fish meal industry uses large amount of heat for drying, and this paper presents results from a feasibility study of the possibilities for energy recovery by means of a hybrid heat pump. By hybrid heat pump means a vapour compression heat pump with a solution circuit. The working fluid is mixture of ammonia and water which gives many benefits where high temperatures are required and where the heat sink and heat source fluids have large temperature glides. A simulation model was developed to explore the possibilities for heat recovery using hybrid heat pumps, and results from parametric studies with simulation model are presented. The results show that hybrid heat pumps have promising capabilities for use in the fish meal industry.

Ammonia heat pump optimization through two condensers in series
Claus Madsen*, B. Pijnenburg, R. Christensen

*Danish Technological Institute (Denmark)

With a relatively large difference in temperature of water in and out of a condenser, it is possible to reduce the required area of the condenser by splitting the condenser into two sections. An alternative is to use the same area but increase the COP by lowering the condensing temperature.
This article describes the potential of splitting the condenser into two sections and under which circumstances this is possible.

Towards "environmentally sound” refrigeration as defined under the Montreal Protocol
Lambert Kuijpers

Technical University of Eindhoven (Netherlands)

Since 2009 many efforts have been undertaken internationally to study limits to HFC consumption. In that year the Montreal Protocol experienced first discussions of the so-called HFC Amendment to the Montreal Protocol, discussions which are still ongoing. In fact, the European F-gas regulation and the MAC directive were the first international HFC regulations that entered into force; the F-gas regulation has already been reviewed recently and a new proposal is currently under discussion. In 2011, in Decision XXIII/9, the Montreal Protocol Parties requested a new report on environmentally benign or friendly ODS alternatives, which was published in 2012. The beginning of 2012, a group of countries established the CCAC, the Climate and Clean Air Coalition, the efforts of which are focused on the reduction of emissions of short-lived climate gases --including HFCs-- via various initiatives, including workshops and conferences. Late in 2012, the Parties to the Montreal Protocol took Decision XXIV/7 in which they request a TEAP Task Force to produce a new report on “environmentally sound” ODS alternatives in 2013. This paper summarises main assessments environmentally acceptable alternatives, and elaborates on the refrigerant alternatives described in two recent TEAP Task Force reports, where the XXIV/7 Task Force report will be subject for discussions at the Montreal Protocol OEWG meeting in Bangkok, June 2013. Refrigerant alternatives should be “environmentally sound”, a definition probably related to refrigerant alternatives having a low GWP, which includes natural refrigerants.

Status and analysis of ammonia refrigeration technology for cold stores in China
Jianyi Zhang

Jimei University (China)

Ammonia is widely used in refrigerating plants in China, where more than 92% of cold stores have adopted it as the refrigerant. The energy efficiency of cold stores is introduced, and the status of equipment used in ammonia refrigeration plants reviewed. The author’s investigations reveal a continuing increase in the size of cold stores and progressive application of screw compressors. Based on field surveys, safety issues around ammonia refrigeration still present a challenge in China. National standards for safety and charging of ammonia systems have recently been issued to address these problems, and the measures in these standards are introduced.

Energy conservation in ammonia refrigeration system installed for meat processing unit in india
Anil Gulanikar

Dag-Tech Refrigeration (India)
In this paper we have elaborated the renewal and improvement carried out in ammonia refrigeration plant installed for a meat processing units in India from energy conservation perspective. We selected two out of four refrigeration systems installed in one meat processing unit for revamping as they were 15 year old. Plant consist of reciprocating compressors, atmospheric condensers, inefficient air cooling units (ACU), and was manually operated without any automation. The discharge pressures were high due to presence of air in the system. The approach/ methodology selected was, formulation of design parameters, introduce automatic compressor capacity control system, replace existing overdesigned compressor jacket cooling pumps, install air purger, replace existing inefficient atmospheric condensers by S & T condensers, replace old inefficient ACU by efficient ACU, install controls to minimize manual operation and educate manpower for safe/efficient plant operation. Designed and installed heat recovery system using compressor discharge gas and using 85°C waste fluids from rendering plant to generate hot water. As all above revamping work to be executed without any production loss, we meticulously planned and executed all above in about four years. Similar activities were successfully carried out in two others meat processing units simultaneously for the same group. The plant is running successfully for last two years. Key achievements were , only 15 out 22 No. compressors were required to operate during peak load, 57% reduction achieved in ACU fan motor installed kW , replacement of 20 No. overdesigned jacket cooling pump achieved 114,624 kW/year energy saving and saved 98,000 lit/year furnace oil due to heat recovery.

Use and misuse of standards in refrigeration
Gert Koster

GEA Refrigeration (Netherlands)

This paper is intended as an introduction to the workshop on use and misuse of standards for commercial reasons. It shows how standardization is organized, what the benefits of standardization can be and what threats can occur in unguarded moments.
INTRODUCTION: Worldwide standards are developed and used for many purposes and applications. It may have been started by agreements on length and weight. These agreements were of local interest in order to be “sure” that on the market place you got delivered the right amount of goods. From this time as example the measure “foot” is known, as if all feet are alike. Normally it was referred to the length of the foot of the king. So, the value could change when the king was succeeded with confusion all over.
Internally in companies and organizations standards are used not only to prevent and/or avoid repetitive work, but also to reduce the risk of making mistakes. By applying standards, in many cases it also results in cost reduction in design and manufacturing.
In after-sales service and maintenance it also has advantages because of the interchangeability of parts.
In daily life, we also see the advantage in having standards for e.g. electrical power supply and the physical dimensions of electrical sockets, traffic signs, etc. During the years the purpose of standards has changed. Some 40 years ago, standards were mainly dealing with dimensioning of e.g. construction elements. Apart from these types of standards, now standards are setting the objectives to be met with regard to safety and safeguarding the environment. The latter in the broadest sense of the word; directly and indirectly by setting a standard for e.g. efficiency and energy consumption. This paper deals with the organization how standards are being set up, how they are approved and how the industry can participate in this and to create awareness of possible misuse of standards.

Ammonia chillers in different industrial plants in Switzerland
Jan Boone

Mayekawa Europe (Belgium)

This paper presents the results of operation of CHILLERS with natural refrigerants in Switzerland. PLANT 1 - NH3-chiller is designed to produce 367 kW chilled ethylene glycol/water at -2/-6˚C with an evaporating temperature of -9˚C. The plant started in the fruit-season 2012 and operated approx. 3716 hrs at an overall COP of 4 to 5.
PLANT 2 uses 2 piston compressors to produce 500kW chilled water at 6°C and 350kW glycol-water at -3°C in a coldstore by using NH3 direct expansion type chillers. The plant was started in 2010 and operated approx. 18000 hrs at an overall COP of 3~4.5.
PLANT 3 - NH3 chillers use piston compressors to produce 250kW cooling in a fruit cold storage plant with ethylene glycol at -7°C by using combined plate in shell evaporators. The plant started in 2011 and operated approx. 16000 hrs at an overall COP of 2.9.

Operating ammonia refrigeration systems at peak efficiency
Sergei Khoudiachov

S K Energy Consulting (Canada)

There are several ways to improve energy efficiency of ammonia refrigeration systems. To save energy, many companies invest in additional condensers, sophisticated PLC’s, and VFD’s. Unfortunately, optimization of the refrigeration plant operation is often overlooked. However, this optimization is the most cost-effective approach to save energy in ammonia industrial refrigeration. By improving the operation of ammonia systems, companies can get 10 – 20 times better return on investments compared to typical investments in energy saving equipment. This technical paper will review practical implementation of the optimized operation. Many existing refrigeration systems can save 10- 20% of the energy use by optimizing condensing pressure, suction pressure, hot gas defrosting, etc. To achieve these energy savings, limited investments are required. However, operators should work as a team with energy efficiency experts to minimize energy use of their refrigeration systems.

New developments on ammonia separation systems
Atte Aarnio

Vahterus Oy (Finland)

Vahterus is an inventor and manufacturer of fully welded Plate&Shell Heat Exchanger since 1990. Recently the company has developed two different kinds of evaporator / separating systems. The target of the developing was to reach a low ammonia charge and compact size unit combined to a safe and environment friendly construction. The first newly developed construction has been named the “Combined Evaporator”. This system performs two functions in one compact cylinder type of round shell; the evaporating section in the bottom and the droplet separating section on the top. Vahterus has its own in-house testing laboratory. It gives the possibility to run NH3 in the system producing a lot of practical testing results; furthermore we have a lot of customer experiences and test results from them. These data has been used in the development process and heat exchanger dimensioning software.
The “Combined Evaporator” was introduced in Chillventa fair 2008. The newest construction revision has been available from the beginning of 2012. Tests have shown that the operation is in line with expectations. Main benefits of using the “Combined Evaporator” are to reach as small footprint and constructional volume as possible; as small charge of ammonia as possible and the possibility to save piping, insulating and transportation charges. Another newly developed construction has been named “Vahterus External System” (“VES”). It is a new version of the two-vessel-system (evaporator + separator). “VES” works with similar technical principle as the “Combined Evaporator”, giving the possibility to minimize the size of the separator vessel and the ammonia charge.
The dimensional size of the “Combined Evaporator” is limited, so on very large duties the “VES” is preferred because it gives the opportunity to reduce the size compared to the traditional heat exchanger and separator. When using the “VES” it is now possible to have a smaller construction for larger capacity units.

Gaining “Lost Work” for a Greener Planet
Henry Bonar*, John Nuszkowski


During the refrigeration cycle – compression, condensing, expansion, and evaporation – a process that occurs during the expansion phase has become known as the lost work process. This process releases energy (flash gas) which could be captured and used to reduce the work by harnessing this energy to drive portions of refrigeration equipment.

Extended operational flexibility of trigeneration systems with ammonia water absorption chillers
Arnd Hilligweg

Nuremberg University of Applied Sciences (Germany)

In a contribution to the 2009 Ohrid Conference (Hilligweg, 2009) a short-cut method for designing trigeneration systems for steady state operation was explained. Here system modifications for non-steady state operation shall be introduced. An interesting approach to this problem was made by Lai and Hui (2010) who suggested to integrate trigeneration systems and thermal storage. However, the selected components were rather conventional: Chilled water or ice storage units. Following the demands of power, heat and cooling it shall be shown in this article that capacities can be supported by store-and-boost-components. Completing cogeneration system (IC-engine or gas turbine) and ammonia-water absorption chiller these components make operation of trigene-ration systems more flexible.

First operation data of a gas absorption heat pump at a test bench
Rupert Graf, Jose Corrales Ciganda, Simon Funk, Annett Kühn, Felix Ziegler

Technical University of Berlin (Germany)

First operation data of a test site with four parallelly operated natural gas driven absorption heat pumps (GAHP) using NH3/H20 as working pair and air as an environmental heat source will be presented. Waste heat of an indoor pool hall is used to raise the heat source temperature. The influence of the resulting high ambient air temperatures - along with additional necessary fans - on the system efficiency will be investigated. In this paper gas utilization efficiencies, auxiliary energy factors and primary energy ratios for high air inlet temperatures above 17 °C will be presented and compared to a system using ambient air as heat source. In addition the influence of the load behaviour on the gas utilization efficiency, auxiliary energy factors and primary energy ratios will be revealed.

Optimization of a gas absorption heat pump system
Jose Corrales Ciganda, Rupert Graf, Annett Kühn, Felix Ziegler

Technical University of Berlin (Germany)

In the course of an energy-efficient modernization of a kindergarten in Berlin a 35 kW gas absorption heat pump using NH3/H2O as working pair has been installed in 2010. Domestic hot water production and space heating are additionally supported by a 15 m2 solar collector. The low temperature heat is supplied to the heat pump system by four 100 m long vertical ground probes.
In this paper operation data for the period 2011-2012 are presented. Gas Utilization Efficiencies (G.U.E.) are calculated and compared for different demand profiles. The comparison of measured G.U.E. values with manufacturer data revealed potential for system optimization. Based on operation analysis modifications of the control strategy and alternative hydraulic set-ups for an improved performance are presented.

Hybrid coabsorbent heat pumping cycles
Mihail-Dan Staicovici, Andrei-Marius Staicovici

S.C. Varia Energia s.r.l. (Romania)

The work presents model results of the nontruncated and simple truncated ammonia-water hybrid coabsorbent heat pumping cycles (Staicovici, 2007). The cooling cyles are run for sink temperatures of 12ºC to 42 ºC and desorber temperatures of -60 ºC to -5 ºC. The depleted heat source temperature has been considered to be by 20 ºC to 40 ºC higher than the sink source. The effectiveness with respect to the pumping and mechanical vapor compression (mvc) work consumption, , shows values ranging within several to one and two orders of magnitude higher as compared to the single-stage mvc cooling cycles. The cooling effectiveness with respect to the heat source consumption is and in case of the nontruncated cycles and simple truncated cycles, respectively. Concerning the heating cycles, these are run for heat source temperatures of 5 ºC, 37 ºC and 70 ºC. The sink source temperature ranges within -50 ºC to +50 ºC. The usefully heated fluid temperature resulted in values of 40 ºC to 140 ºC. The values of the heating cycles are quite similar to those of the cooling ones, whyle the heating effectiveness with respect to the heat source consumption is . The results are very encouraging for use of the hybrid coabsorbent cycles in heat pumping applications with high primary energy savings.

Influence of ejector performance on the overall efficiency of ammonia ejector refrigeration cycle
Krzysztof Banasiak, Armin Hafner, Anne Karin Hemmingsen

SINTEF Energi AS (Poland, Norway)

The influence of ejector performance on the overall efficiency of ammonia ejector refrigeration cycle in different operating conditions was numerically assessed and discussed. A brief review of experimental results reported in scientific literature was performed and commented, specifically with reference to limited values of ejector efficiency (up to 18%). Physically and technically based thresholds for further increment of ejector performance were presented.
Sample operation curves for the ejector layouts reported in literature as well as potential degrees of freedom for optimization of the ejector design were suggested and discussed, based on the results of numerical simulations carried out by authors’ own one-dimensional ejector model.

Exergetic analysis of refrigeration cycles operating with natural refrigerants
C. Filipoiu, A. Dobrovicescu, V.Apostol, L. Drughean

University Politehnica of Bucharest (Romania)

Comparative analysis of the design and operation of two different solutions for a supermarket cold chain located in Bucharest Romania is presented. The actual system operates with R404A in a single stage for cooling and two stages for freezing while the replacing one (alternative) considers a cascade CO2/NH3 system. The analysis is performed based on the exergy concept. The exergy analysis points out which are the exergy destructions associated to every piece of equipment and processes offering solutions for improvement. Based on the exergetic analysis an exergoeconomic optimization can be developed. The conduct of the cascade system at the variation of the operating parameters is performed.

Romania – Ammonia traditional user
Gratiela Tarlea

Technical University of Bucharest (Romania)

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.
Romania has ratified the Vienna Convention for the Preservation of Ozone Layer, the Montreal Protocol on ozone depleting substances and its Amendment adopted in London in 1993, followed by ratification of the Copenhagen and the Montreal Amendment in 2000 and 2001, respectively. In the last years, the refrigeration, air conditioning and heat pump industry made important technical progress and complied with the Montreal and Kyoto Protocols.