Thermodynamic properties of difluoromethane (HFC-32) are expressed in a 35-termcrossover equation of state. This equation of state is effective at pressures up to 35MPa,densities up to 1450 kg.m-3, and temperatures fr...Thermodynamic properties of difluoromethane (HFC-32) are expressed in a 35-termcrossover equation of state. This equation of state is effective at pressures up to 35MPa,densities up to 1450 kg.m-3, and temperatures from 150 K to 480 K, respectively. Equations for Helmholtz energy, Gibbs energy, internal energy, enthalpy, entropy, isochoric heatcapacity, isobaric heat capacity, speed of sound, and second virial coefficient of HFC-32 arepresented. Independent equations are also included for vapor pressure and saturated liquiddensity as function of temperature.展开更多
The paper reports the measurements of the thermal conductivity of gaseous HFC32 over the temperature range 254.51K to 341.76K near the saturation line. The thermal conductivities were measured in a transient hot-wire ...The paper reports the measurements of the thermal conductivity of gaseous HFC32 over the temperature range 254.51K to 341.76K near the saturation line. The thermal conductivities were measured in a transient hot-wire instrument employing two anodized tantalum wires as the heat source with an uncertainty of 1%. The resuilts were correlated as a function of temperature for engineering use.展开更多
The specific heat capacities of HFC152a/HFC32(92%/8% wt) mixture in liquid phase used in the refrigerator as an alternative for CFC12 are determined and 32 values of heat capacity are reported in this paper.The puriti...The specific heat capacities of HFC152a/HFC32(92%/8% wt) mixture in liquid phase used in the refrigerator as an alternative for CFC12 are determined and 32 values of heat capacity are reported in this paper.The purities of HFC152a and HFC32 are all 99.95%.The flow apparatus for measuring heat capacities of liquid phase compounds and their mixtures under the pressure up to 12 MPa,and at temperatures from 26OK to 47OK was built by the authors.展开更多
The speed of sound of the gaseous difluoromethane (HFC-32) and trifluoroiodomethane(CF3I) are measured with a cylindrical, variable-path acoustic interferometer operating at156.252 kHz. Temperatures ranged from 273.15...The speed of sound of the gaseous difluoromethane (HFC-32) and trifluoroiodomethane(CF3I) are measured with a cylindrical, variable-path acoustic interferometer operating at156.252 kHz. Temperatures ranged from 273.15 K to 333.15 K for both and pressures rangedfrom 48 kPa to 390 kPa for HFC-32 and from 58 to 276 kPa for CF3I, respectively Theuncertainty of the speed of sound was less than ±0.1%. The ideal-gas heat capacity atconstant pressure and the second acoustic virial coefficients for HFC-32 and CF3I werealso determined over the temperature range from the speed of sound measurements. Theideal-gas heat capacities at constant pressure and second virial coefficients calculated fromthese speed of sound measurements for both were compared with results from the literaturedetermined from PVT measurements and from speed of sound measurements, respectively.The uncertainty of the ideal-gas heat capacities at constant pressure were estimated to beless than ±1%.展开更多
文摘Thermodynamic properties of difluoromethane (HFC-32) are expressed in a 35-termcrossover equation of state. This equation of state is effective at pressures up to 35MPa,densities up to 1450 kg.m-3, and temperatures from 150 K to 480 K, respectively. Equations for Helmholtz energy, Gibbs energy, internal energy, enthalpy, entropy, isochoric heatcapacity, isobaric heat capacity, speed of sound, and second virial coefficient of HFC-32 arepresented. Independent equations are also included for vapor pressure and saturated liquiddensity as function of temperature.
文摘The paper reports the measurements of the thermal conductivity of gaseous HFC32 over the temperature range 254.51K to 341.76K near the saturation line. The thermal conductivities were measured in a transient hot-wire instrument employing two anodized tantalum wires as the heat source with an uncertainty of 1%. The resuilts were correlated as a function of temperature for engineering use.
文摘The specific heat capacities of HFC152a/HFC32(92%/8% wt) mixture in liquid phase used in the refrigerator as an alternative for CFC12 are determined and 32 values of heat capacity are reported in this paper.The purities of HFC152a and HFC32 are all 99.95%.The flow apparatus for measuring heat capacities of liquid phase compounds and their mixtures under the pressure up to 12 MPa,and at temperatures from 26OK to 47OK was built by the authors.
文摘The speed of sound of the gaseous difluoromethane (HFC-32) and trifluoroiodomethane(CF3I) are measured with a cylindrical, variable-path acoustic interferometer operating at156.252 kHz. Temperatures ranged from 273.15 K to 333.15 K for both and pressures rangedfrom 48 kPa to 390 kPa for HFC-32 and from 58 to 276 kPa for CF3I, respectively Theuncertainty of the speed of sound was less than ±0.1%. The ideal-gas heat capacity atconstant pressure and the second acoustic virial coefficients for HFC-32 and CF3I werealso determined over the temperature range from the speed of sound measurements. Theideal-gas heat capacities at constant pressure and second virial coefficients calculated fromthese speed of sound measurements for both were compared with results from the literaturedetermined from PVT measurements and from speed of sound measurements, respectively.The uncertainty of the ideal-gas heat capacities at constant pressure were estimated to beless than ±1%.
