Working fluids-important factors Physical-thermodynamic qualities -Normal boiling point(at 1,013 bar) -Vapor pressure curve-critical temperature(Tc)and pressure(Pc): Refrigeration process-process losses .Pressure level-pressure rating of components(21-23/38 bars operation pressure) .Pressure ratio-efficiencies of the compressor -Molecule weight: Heat of evaporation-mg pipe diameters Temperature in the exit of compressor -Volumetric refrigeration capacity-Ah.gas density [kJ/m3] .Gives necessary compressor volume [m] Thermo physical properties -Specific heat capacity,co [kJ/(kgK)] -Viscosity,v[mm2/s] -Thermal conductivity,[W/(mK)] ONTNU ②SINTEF Working fluids-important factors cont. 。Other factors -Chemical stability -Material compatibility(corrosion,reactions) 一Vater solubility -Miscibility with different types of oils/lubricants -Electric resistance Price and availability Environmental friendliness-safety Impact on ozone layer(ODP-Ozone Depleting Potential) -Contribution to the greenhouse effect(GWP-Globa/Warm -Toxicity,inflammability,odor etc. 回NTNU SINTEF5 Working fluids – important factors • Physical – thermodynamic qualities – Normal boiling point (at 1,013 bar) – Vapor pressure curve – critical temperature (TC) and pressure (PC): • Refrigeration process – process losses • Pressure level – pressure rating of components (21-23/38 bars operation pressure) • Pressure ratio – efficiencies of the compressor – Molecule weight: • Heat of evaporation – mR , pipe diameters • Temperature in the exit of compressor – Volumetric refrigeration capacity – Dh • gas density [kJ/m3 ] • Gives necessary compressor volume [m3 ] • Thermo physical properties – Specific heat capacity, cp [kJ/(kgK)] – Viscosity, n [mm2 /s] – Thermal conductivity, l [W/(mK)] 6 • Other factors – Chemical stability – Material compatibility (corrosion, reactions) – Water solubility – Miscibility with different types of oils / lubricants – Electric resistance • Price and availability • Environmental friendliness - safety – Impact on ozone layer (ODP - Ozone Depleting Potential) – Contribution to the greenhouse effect (GWP - Global Warming Potential) – Toxicity, inflammability, odor etc. Working fluids – important factors cont