Les points saillants de la conférence IIF d'Ohrid

Résumé de quelques communications présentées à la récente conférence IIF d'Ohrid en avril 2015 sur les technologies frigorifiques à l'ammoniac et au CO2. (en anglais)
The 6th IIR conference on Ammonia and CO2 Refrigeration Technologies held in Ohrid, Macedonia, FYROM, proved highly successful. Highlights from some of the 54 papers presented were:

. A. Hafner from SINTEF (Norway) presented at the plenary session an overview* for the development possibilities during the next years to further increase the market share of CO2 refrigeration and heat pump systems such as commercial refrigeration (supermarket refrigeration, light and stand-alone units, condensing units, transport refrigeration (containers, truck and trailer units), vehicle air conditioning & heat pumping, domestic hot water heat pumps and industrial applications.
In concordance with the news on the “Growth of CO2 refrigeration”, this paper stated that CO2 ejector supported units with parallel compression do have a highest energy efficiency advantage compared to HFC-404A units, followed by a standard booster system equipped with an external mechanical subcooling system.
Other papers by A. Schroeder and J. Koehler; E.Krieri et al ; S.Minetto et al covered the performance of CO2 ejectors.
*2020 perspectives for CO2 refrigeration and heat pump systems, A. Hafner; downloadable via Fridoc: http://goo.gl/cZTk75

. Innovative applications of CO2 refrigeration has been highlighted during this conference such the utilization of the heat recovery of valuable discharge temperature of transcritical applications as described in the M. Karampour’s et al. paper* from KTH, (Sweden) in supermarket refrigeration.
A main focus of the research has been on CO2 transcritical booster system, as the emerging solution in the Swedish market, where its performance has been often compared with the conventional HFC solutions where performance comparisons have been performed.
The heat recovered is used for heating application with variation of COP of 3.5 to 5 depending of the discharge pression and cooling demands. Similar figures of COP including heat recovery have been reported in other papers of I.Colombo et al. and N.Fidorra et al.
*Review of supermarket refrigeration and heat recovery research at KTH-Sweden; downloable via Fridoc: http://goo.gl/gAvDwC

. Beer production is a sophisticated process with high energy consumption and abundant energy conversion involved. In large breweries (refrigeration capacities of several MW), electrical energy consumption for refrigeration represents a large share of it and any optimization in this area can have noticeable influence on the overall cost of production.
This is one of the reasons why ammonia is still the dominant refrigerant in large breweries.
A paper by I. Vanjur and V. Sovilj presents an analysis of refrigeration load in a large brewery located in Serbia and, as a result, several possible solutions could address high amplitude of refrigeration demands and reduce electrical energy consumption of ammonia refrigeration compressors:
- One-step cooling of wort allows reduction of peak demands on the refrigeration plant.
- Introduction of two evaporation temperatures in compressor plant – when usual practice in breweries is to have one evaporation temperature – could reduce the electrical consumption of refrigeration compressors by up to 13%.
- Floating pressure control, which aims to find optimal condensing pressure at any given time, allows reduction of electricity consumption by 10-12%.
Reducing energy consumption of ammonia refrigeration compressors in large breweries, I. Vanjur, V. Sovilj; downloadable via Fridoc: http://goo.gl/ZAVdx1