Department News
Thermal Conductivity and Surface Tension of Refrigerants
Seminar Date
2000-06-15
Author
관리자
Date
2000-06-15
Views
1161
1. 제목 : Thermal Conductivity and Surface Tension of Refrigerants
2. 연사 : Professor Bernard Le Neindre
University of Paris 13
Avenue J. B. Clement
Villetaneuse 93430 France
3. 일시 : 1999년 12월 6일 (월요일) 16:30 - 17:30
4. 장소 : 신공학관 (301동) 1512호
5. 내용 :
Measurements of the thermal conductivity of alternative refrigerants performed in a coaxial cylinder apparatus, in the temperature range from 300 to 500 K and at pressures up to 500bar are presented. The measurements allow analysis of the data based on the residual concept. The transport property surface is separated into four regions the gaseous state (at P = 1.01325 bar), the dense state, the subcritical region (T < TC), and the supercritical region (T > TC). In the dilute gas region, we show that the thermal conductivity can be represented by an expression derived from the kinetic theory of gases, using potential parameters obtained from the corresponding equation of viscosity, with an accuracy of 2.5%. In the liquid range our data are compared to those obtained at Seoul National University. In the subcritical region, a strong increases of the thermal conductivity was observed when the heat flux is parallel to the interface corresponding to the liquid-gas coexistence curve. In the supercritical region, our experimental data are compared to the corresponding values calculated by the mode-mode coupling theory.
In the critical region, the concept of two-scale-factor universality was used to predict the capillary length amplitude and the surface tension amplitude near critical vapor and liquid phases. Furthermore, it was observed from experimental works, that the capillary length and the surface tension of many fluids follow power laws in reduced temperature from the triple point to the critical point, with universal exponents, respectively 0.935 and 1.26. Universal amplitudes values were derived and used to calculate the capillary length and the surface tension of refrigerants. Mean deviations between calculated and experimental data are within 3.5%, and are of the same order of magnitude that the accuracy of experimental data.
6. 문의 : 김민수 교수 (☏ 880-8362)
2. 연사 : Professor Bernard Le Neindre
University of Paris 13
Avenue J. B. Clement
Villetaneuse 93430 France
3. 일시 : 1999년 12월 6일 (월요일) 16:30 - 17:30
4. 장소 : 신공학관 (301동) 1512호
5. 내용 :
Measurements of the thermal conductivity of alternative refrigerants performed in a coaxial cylinder apparatus, in the temperature range from 300 to 500 K and at pressures up to 500bar are presented. The measurements allow analysis of the data based on the residual concept. The transport property surface is separated into four regions the gaseous state (at P = 1.01325 bar), the dense state, the subcritical region (T < TC), and the supercritical region (T > TC). In the dilute gas region, we show that the thermal conductivity can be represented by an expression derived from the kinetic theory of gases, using potential parameters obtained from the corresponding equation of viscosity, with an accuracy of 2.5%. In the liquid range our data are compared to those obtained at Seoul National University. In the subcritical region, a strong increases of the thermal conductivity was observed when the heat flux is parallel to the interface corresponding to the liquid-gas coexistence curve. In the supercritical region, our experimental data are compared to the corresponding values calculated by the mode-mode coupling theory.
In the critical region, the concept of two-scale-factor universality was used to predict the capillary length amplitude and the surface tension amplitude near critical vapor and liquid phases. Furthermore, it was observed from experimental works, that the capillary length and the surface tension of many fluids follow power laws in reduced temperature from the triple point to the critical point, with universal exponents, respectively 0.935 and 1.26. Universal amplitudes values were derived and used to calculate the capillary length and the surface tension of refrigerants. Mean deviations between calculated and experimental data are within 3.5%, and are of the same order of magnitude that the accuracy of experimental data.
6. 문의 : 김민수 교수 (☏ 880-8362)
