Thermal conductivities of new refrigerants R125 and R32 measured by the transient hot-wire method

Abstract

Thermal conductivity measurements are reported for the new refrigerants pentafluoroethane (R125) and difluoromethane (R32), which are suggested to replace chlorodifluoroethane (R22) as components of a mixture. Transient hot-wire experiments were performed which cover both the liquid and the vapor states at temperatures and pressures ranging from t = -40 to 90°C and from p = 1 to 60 bar. Uncertainties keep within 1.6 % for liquid and 2.0 % for vapor states. The results are correlated with density and temperature. In addition, temperaturedependent correlations are presented for practical calculations for (i) saturated liquid, (ii) saturated vapor, and (iii) dilute gas (which approximately equals the vapor state at ambient pressure). Finally, the results are compared with data from the literature and also with the respective thermal conductivities of R22.

Behavior of thermal diffusion of hydrofluorocarbon HFC-32 near the critical region

“…For liquid phase the measured values are in agreement with previously published data especially with those of Wakeham et al [2], Grebenkov et al [3], Gross et al [8], Ro et al [10] and Geller et al [12] within the combined experimental error. In table 2: τ = T/Т кр -reduced temperature, ω = ρ/ ρ кр -reduced density, λ -thermal conductivity.…”

Equations for the Thermal Conductivity of R-32, R-125, R-134a, and R-143a

“…However, Kruppa and Straub [33] and Pitschmann and Straub [14] reported thermal diffusivity Grebenkov et al [7]; (∇) Gross and Song [8]; (+) Le Neindre and Garrabos [9]; (♦) Papadaki and Wakeham [10]; ( ) Ro et al [11]; ( ) Tanaka et al [12]; (×) Yata et al [13]. (10) In the conversion from the thermal diffusivity to the thermal conductivity, values of density and isobaric heat capacity are needed.…”

“…Data sets of the thermal conductivity of R-32 [4][5][6][7][8][9][10][11][12][13][14], R-125 [4,7,8,10,[12][13][14][15][16][17][18][19][20][21][22][23], R-134a [7,11,15,[24][25][26][27][28][29][30][31][32][33], and R-143a [13,14,30,34,35] considered in the present formulation are listed in Tables I to IV. Experimental data for R-32 are also shown in Fig.…”

“…Assael and Karagiannidis [4];( ) Gao et al[5]; ( ) Grebenkov et al[7]; (∇) Gross and Song[8]; (+) Le Neindre and Garrabos[9]; (♦) Papadaki and Wakeham[10];( ) Ro et al[11]; ( ) Tanaka et al[12]; (×) Yata et al[13].…”

“…)Assael and Karagiannidis[4]; ( ) Gao et al[5]; ( ) Geller and Paulaitis[6]; ( ) Grebenkov et al[7]; (∇) Gross and Song[8];…”