Exclusive interview with Alexander Cohr Pachai, Johnson Controls

By Sabine Lobnig, Oct 21, 2011, 09:35 5 minute reading

At the 23rd IIR International Congress of Refrigeration ammonia21.com spoke to Alexander Cohr Pachai, Technology Manager of Industrial Refrigeration at Johnson Controls about the benefits, payback period and future uses of heat pumps using natural refrigerants, in particular ammonia.

ammonia21.com: You presented a paper at the 23rd IIR International Congress of Refrigeration on “Heat pumps using natural refrigerants for optimising efficiency and minimising environmental impact”. Could you tell us about the added value of installing an ammonia heat pump and what you see as its unique benefits?
Alexander Cohr Pachai: Until recently nobody has really been thinking about the heat that is emitted by a normal refrigeration system. The condenser side emits the cooling capacity in addition to which there is the power input you put into the compressor, all of which is lost as waste heat. In the past energy has been too cheap for people to bother about collecting this waste heat. Now with the new ammonia heat pump you can evaporate at 30°C – 40°C and then you can boost the heat up to a valuable temperature for cleaning processes, such as for in slaughter houses for example, where you need to clean very effectively using 90°C water to remove bacteria. You can produce this hot water to be used at night by running the ammonia heat pump during the day. 
We need to rethink the way we use energy now because the energy prises have risen dramatically. It is worth investing in heat pumps, and the payback time is relatively short in many cases if the alternative is a gas or oil boiler. It is good for business, and is not only a technology for being green. Heat pumps with ammonia can also produce warmer water than a lot of other alternatives as it doesn’t suffer from chemical breakdown – ammonia is very stable, making it appropriate for such purposes.
ammonia21.com: Which industries have you have identified as good candidates for ammonia heat pump installations and what payback period can be expected?
Alexander Cohr Pachai: We have been looking at different solutions to recover energy from gas process plants where for example hydrogen and other gases are dealt with. These plants produce quite a lot of heat over the year and could actually sell the heat if they raised the temperature to produce hot water. Using an ammonia heat pump such plants could boost temperatures to 70°C, which is high enough for the gas processing plant to sell the heat to a district heating installation. The gas plant would have payback period of about 0.9 years. This is a rough calculation as there are lots of factors you have to know and to take into consideration, such as loading and unloading, and the data we collected so far were not very detailed.
We are now looking into two projects in Denmark that could use ammonia heat pumps and feed the heat into a district heating system, and also into a few breweries in the Middle East, where a lot of hot water is used to clean bottles.
ammonia21.com: You mention district heating. There is an ammonia heat pump installation that harnesses the background heat from ambient seawater to supply hot water to a district heating installation in Drammen, in Norway? Do you know of any other such installations?
Alexander Cohr Pachai: In Denmark we had a systems using the sea water vapour as working fluid in Augustenborg, Denmark. I don’t know if it is still in operation. To my knowledge there are no others doing it in the same way as in Drammen, but in Denmark we have about 700 small district heating plants where an ammonia heat pump would fit very well because you can then take advantage of the low energy tariffs at certain times of day. There is a huge potential and we are starting to investigate the possibilities. We have tested the ammonia heat pump unit, so we know it works. We will launch the product  at the end of this year.
ammonia21.com: There is considerable interest in the Middle East in district cooling as a solution to tackling rising energy demand. What is the potential for ammonia heat pump installations in this region?
Alexander Cohr Pachai: District Cooling is already big in Finland and in Stockholm in Sweden, so we know how it works and have already supplied a lot of the equipment. With regard to the Middle East, we have yet to come across any interesting district heating/cooling projects that could benefit from an ammonia heat pump.
ammonia21.com: Can you tell us a little more about the potential for ammonia heat pumps in breweries?
Alexander Cohr Pachai: A lot of breweries have cooling towers emitting a lot of heat and water, and this heat can of course be recovered and put into a heat pump. Water at 30°C is not very useful, which is why it is regarded as waste, but in the future it could be used as the energy source for heat pumps. This is particularly simple if the cooling load coincides with the heating load, otherwise you have to think more carefully about how collect the heat and combine it with needs.
ammonia21.com: What are the strategic challenges regarding achieving greater market penetration of ammonia heat pumps?
Alexander Cohr Pachai: The biggest challenge is to convince the customer because many customers are sceptical of the short payback times and say ‘you’re pulling our leg’! Of course with better quality data we can improve the accuracy of our payback time calculations. However, we have well developed calculation models that people can use themselves. Perhaps they can use them to convince themselves that such installations are a good idea.
Psychology is still the biggest barrier facing the implementation of natural refrigerants.
ammonia21.com: We have recently reported on a lack of trained ammonia technicians to fill demand, in particular in the US, do you see this is as a particularly pressing problem that needs to be addressed?
Alexander Cohr Pachai: The biggest threat for natural refrigerants is accidents, and we need to avoid them by ensuring we have well trained personnel. Unfortunately accidents happen, but then again they also occur with fluorinated refrigerants. For example there was an incident in Korea not so long ago, so accidents can happen with any refrigerant.


By Sabine Lobnig

Oct 21, 2011, 09:35

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