TOOLS
Tools for CO2 H
aving identified a high demand for relevant tools early on, Refco
18
now offers suitable solutions. The tools presented also cover some transcritical refrigeration systems and are a must for refrigeration technicians. They are optimally designed for requirements in the field and feature the highest levels of reliability, precision, and safety. R744 is a highly popular alternative refrigerant and there has been a striking increase in the number of new refrigeration systems using R744. Carbon dioxide as a refrigerant is considered to be environmentally friendly as it has a very low global warming potential (GWP) of 1, and an ozone depletion potential (ODP)
of zero. The availability of CO2 is ensured from natural sources and by technological advances in recovery from process gases. However, it has clearly different thermodynamic properties than the refrigerants primarily used up to now.
The resulting higher system requirements include: ■ High pressures up to 150 bar. ■ Greatly increasing pressures at moderately increasing temperatures. This requires a high strength of the components and appropriate safety measures. The system must be secured against bursting components.
■ Very high pressures on the low-pressure side of 35-50 bar.
■ The system environment requires CO2
sensors
for monitoring the CO2 concentration in the ambient
air.
■ Due to the small change in volume during condensation, the component design can be smaller.
is under discussion not only in refrigeration technology, but in the context of climate change as well. CO2
Future prospects of CO2 CO2
is considered to
be environmentally friendly in the refrigeration sector. However, CO2
emitted from
burning fossil fuels is thought to be an indicator of greenhouse gas emissions by humans in
the climate debate. The CO2 concentration in atmospheric air shows that we have an impact on the climate. The average concentrations of CO2
in the past 100 years from 300 ppm to 400 ppm. CO2
stems mainly from by- products of industrial processes, but comes also from natural sources. Unlike the components of synthetic refrigerants, CO2
is
present everywhere in the air. If every refrigeration technician could draw CO2
fill it into refrigeration cycles, or if refrigeration equipment could autonomously recover leaked CO2
from the air, the
transportation of refrigerants would become obsolete and there would be no additional emission of greenhouse gases. The relevant technologies exist, but their cost-effectiveness must be proven.
The installation and maintenance of R744
from the air and
Refco is introducing new equipment for R744 (carbon dioxide) based refrigeration systems.
refrigeration systems poses various special challenges for refrigeration technicians: ■ The refrigerant has very high pressures at moderate temperatures.
■ Components suitable for high pressures and CO2
must be selected. ■ The uncontrolled
decompression to atmospheric pressure leads to the formation of dry ice (solid carbon dioxide) that can block refrigeration cycles and cause cold burns.
■ CO2
is an inert gas and high concentrations can lead to asphyxiation.
■ An alarm system is required to detect high CO2
during installation and maintenance.
have risen When working with CO2 , the
refrigerant has the advantage that at low concentrations below 5000 ppm it is neither poisonous nor dangerous. Studies have shown only that concentrations above 1500 ppm lead to a slight reduction of cognitive performance. However, excessively high concentrations of CO2
can cause asphyxiation. These concentrations are several times more than the MWC level of 5000 ppm (MWC: maximum workplace concentration). Compliance with the relevant limits can be reliably monitored today with reasonably priced measuring equipment.
Properties of the tools The Refco product portfolio
concentrations
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