FEATURE

INCORPORATING COLD CHAIN

By eurammon

According to an analysis by the Umweltbundesamt ( German federal environmental agency ) in 2014 , refrigeration alone accounts for 14 % of Germany ’ s overall energy consumption , and is responsible for about 5 % of direct and indirect greenhouse gas emissions . In consideration of national and international climate protection goals , it is imperative that climatefriendliness in the refrigeration sector be improved . An important contribution can be made by using natural refrigerants such as R723 , which is particularly environmentally friendly with an ozone depletion potential ( ODP ) of 0 and a global warming potential ( GWP ) of 8 . It also offers great investment security for operators of refrigeration systems , since the refrigerant bans of the EU regulation on fluorinated greenhouse gases don ’ t apply to it .

Efficient for low refrigerating capacity ranges

The refrigerant ammonia dimethyl ether consists of 60 % ( by mass ) of ammonia ( R717 ) and 40 % of dimethyl ether ( RE170 ) — a propellant gas whose refrigerant properties are similar to those of isobutane . Thanks to its azeotropic boiling behaviour , the mixture can be used like a mono-refrigerant , that is , there is no concentration shift during evaporation or condensation . R723 is particularly efficient in the low capacity range up to 100kW .

The circulating volume flow rate of the vapour phase is about 150 % of that of ammonia , which means acceptable pipe cross sections and flow velocities even for lower refrigerating capacities . Also , R723 has a higher volumetric refrigerating capacity than ammonia , so it is possible to obtain considerably higher refrigeration capacities with the same quantity of R723 . In refrigerating systems tested with both ammonia and R723 , the coefficient of performance ( COP ) improved by 7 % when using the latter . Besides its energy efficiency , the azeotropic mixture also features a high

The environmentally friendly and cost-efficient refrigerant R723 convinced the foodproducing company Herrmannsdorfer Landwerkstätten .

performance coefficient and good oil solubility . “ In principle , ammoniabased cooling systems can be filled and operated with R723 . However , the individual application must always be taken into consideration — this is why the conversion should always be clarified with the individual component manufacturers ,” explains Bernd Kaltenbrunner , member of eurammon and CEO of KWN Engineering GmbH .

The energy efficiency of the azeotropic mixture is complemented by a high performance coefficient and a high level of oil solubility . A further great advantage results in the about 15K lower

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1 . Th . WITT Kältemaschinenfabrik GmbH installed a chilled-brine compact refrigeration unit , tailormade for the specific requirements of Herrmannsdorfer Landwerkstätten .