PDF Publication Title:
Text from PDF Page: 019
Figure 2.4. Pareto front (x) for the simple vapour compression cycle (air conditioned application) (McLinden, 2014) 2.2.2. Chemical characteristics Chemically, the working medium has to be stable and inert, though stability has to be reasonable – the refrigerant has to decompose in the atmosphere in a not too long time. Moreover, absence of flammability and toxicity are ideal, as well as negligible effects on the environment (Rothlin, 2011). In order to avoid corrosive compounds, the moisture level of the system should be kept low. Furthermore, in case it existed as free water and the temperature reached levels below the freezing point of water, ice would form on the expansion device and in the evaporator, resulting in malfunctioning of the system by impeding the refrigerant to flow properly. In general, the effect of the moisture is highly dependent on the fluid in use, as the absorption potential can vary greatly (Rothlin, 2011). The refrigerant will encounter oil in the system, specifically in the compressor, and thus must be stable relatively to it (Rothlin, 2011). 2.2.3. Safety Concerning safety parameters, ASHRAE Standard 34 classifies refrigerants based on their toxicity and flammability levels. Specifically, classes A and B categorize the toxicity – namely class A identifies refrigerants for which toxicity has not been found at concentrations less than or equal to 400 ppm; class B those with evidence of toxicity at concentrations below 400 ppm. Belong to class B notably NH3. Groups 1, 2 and 3 identify a growing flammability at given conditions of temperature (21°C), pressure (101 kPa) and heat of combustion. In addition, a class named “A2L” has been introduced in order to keep into account those refrigerants with mild flammability but high ignition power and low burning velocity (Institut International du Froid, 2011). The traditional refrigerants such as R410A and R134a belong to group 1, whereas all the hydrocarbons, such as propane and propylene, belong to group 3. In group 2 R152a can be found, whereas R32 along with the majority of the new HFOs such as R1234yf and R1234ze(E) belong to group 2L. -10-PDF Image | Next generation of refrigerants for residential heat pump systems
PDF Search Title:
Next generation of refrigerants for residential heat pump systemsOriginal File Name Searched:
MartinaLonghini_ThesisReport.pdfDIY PDF Search: Google It | Yahoo | Bing
CO2 Organic Rankine Cycle Experimenter Platform The supercritical CO2 phase change system is both a heat pump and organic rankine cycle which can be used for those purposes and as a supercritical extractor for advanced subcritical and supercritical extraction technology. Uses include producing nanoparticles, precious metal CO2 extraction, lithium battery recycling, and other applications... More Info
Heat Pumps CO2 ORC Heat Pump System Platform More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)