Until now refrigerants R134a and R407c have usually been used
in rail air conditioning systems. These use fluorinated hydrocarbons (FHC and
HFHC). These types of refrigerant are significantly more environmentally
friendly than the CFC/HCFC refrigerants that were banned in the Montreal
Protocol of 1987, and have no ozone-depleting potential but still have a
considerable greenhouse effect potential and contribute towards global warming.
Against the background of worldwide efforts in climate protection, there
is heightened interest in environmental policy on the replacement of these
hydrocarbons with natural refrigerants. As these do not contribute towards
depletion of the ozone layer, unlike synthetic refrigerants, and have either no
or very little direct influence upon the greenhouse effect, they are unrivalled
in terms of climate aspects.
The use of natural refrigerants pays off in
terms of economical aspects. The refrigerants themselves are very cheap, which
has a positive effect on the running costs when initially filling a piece of
equipment and in terms of leakage loss. Natural refrigerants are also highly
efficient and they are very inexpensive to dispose of. |
The refrigerant CO2 (R744) holds top position among the natural
refrigerants under discussion in the area of mobile air conditioning. After
researching various alternatives to the currently used refrigerants, companies
in the German automobile industry for example have agreed to be the first to use
R744 (carbon dioxide) in the future in vehicle air conditioning systems.
Measures such as this can, for example, reduce the direct greenhouse
effect of an air conditioning system by a factor of 1,300 compared with R134a.
Other advantages of CO2-driven air conditioning systems are the
extremely compact dimensions of the system due to the high volumetric
refrigerating capacity of CO2, as well as the fact that the working medium CO2
enables a particularly intensive heat pump function due to its thermodynamic
properties. A fact that such air conditioning systems are already predestined
for use as heat pumps for heating purposes in the area of rail.
As one
of the pioneers of this technology, the refrigeration plant manufacturer Bock
based near Stuttgart has been involved in the development of refrigeration
compressors for the use of CO2 in refrigeration/air conditioning systems since
the start of the 1990s.
At this year's Innotrans, the company presented
the RKX radial piston compressor - an extremely compact solution for using CO2
in rail air conditioning that is already being trialled in the first trains and
has been certified for use in rail according to DIN EN 61373.
For
decades Bock Kältemaschinen GmbH has been supplying well-known train and air
conditioning system manufacturers with refrigerant compressors and is also one
of the worldwide market leaders in mobile refrigeration and air conditioning. |
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