Three steam distillation devices (D-1, D-2 and D-4) or one simultaneous distillation (D-3, water-diethyl ether) as well as the process of CO2-SFE (Supercritical fluid extraction) were adopted in extraction of essentia...Three steam distillation devices (D-1, D-2 and D-4) or one simultaneous distillation (D-3, water-diethyl ether) as well as the process of CO2-SFE (Supercritical fluid extraction) were adopted in extraction of essential oils from Chinese-fir (Cunninghamia lancedata (Lamb) Hook.) and the chemical components of the extracted essential oil were analyzed by Gas chromatograph-MS analyses. The results showed that the essential oil could be almost extracted out within 2 hours and the device-3 had the highest extraction efficiency. The major chemical component of the oil was cedrol. The yield of the extracted essential oils from Chinese fir decreased gradually with the increase of the distillation time. The best condition for extraction by means of CO2-SFE is 100 kg·cm?2 in pressure and 40°C in temperature for. Keywords Chinese fir - Essential oil - Cedrol - Supercritical fluid extraction CLC number S781.4 Document code A Foundation item: This paper was support by the Key Foundation Research Project (G1999016001) of China and the Japan International Cooperation AgencyBiography: HUANG Luo-hua (1957-), male, Research associate, Research Institute of Wood Industry, Chinese Academy of forestry, Beijing 100091, P. R. ChinaResponsible editor: Song Funan展开更多
A non-isothermal injection molding process for a non-Newtonian viscous pseudoplastic fluid is simulated.A conservative interface capturing technique and the flow field solving method are coupled to perform a dynamic s...A non-isothermal injection molding process for a non-Newtonian viscous pseudoplastic fluid is simulated.A conservative interface capturing technique and the flow field solving method are coupled to perform a dynamic simulation.The validity of the numerical method is verified by a benchmark problem.The melt interface evolution versus time is captured and the physical quantities such as temperature,velocity and pressure at each time step are obtained with corresponding analysis.A"frozen skin"layer with the thickness increasing versus time during the injection process is found.The fact that the"frozen skin"layer can be reduced by increasing the injection velocity is numerically verified.The fountain flow phenomenon near the melt interface is also captured.Moreover,comparisons with the non-isothermal Newtonian case show that the curvatures of the interface arcs and the pressure contours near the horizontal mid-line of the cavity for the non-Newtonian pseudoplastic case is larger than that for the Newtonian case.The velocity profiles are different at different positions for the non-Newtonian pseudoplastic case,while in the case of Newtonian flow the velocity profiles are parabolic and almost the same at different positions.展开更多
The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volu...The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volume force. The motion equation of fluid and the hydrokinetics equations of rotating pipe were described in the Cartesians coordinates. The equations showed that the solutions to hydrokinetics equations of rotating pipe in the crossed electric and magnetic electromagnetic field were highly complicated and numerical calculations were also astronomical. The pressure distribution and temperature distribution of one dimension were solved using the electromagnetic equations set. The results showed that the fluid in rotating pipe was in the asymmetrical pressure field and temperature field because it was in the energy exchange and thermo-electrical coupling course. The primary characteristic of flow course could be expressed using the proposed hydrokinetics equations.展开更多
Liquids to be broken up using a prefilming airblast atomizer are usually Newton liquids with relatively low viscosities.While in some industrial processes,such as spray drying,liquids to be atomized are high concentra...Liquids to be broken up using a prefilming airblast atomizer are usually Newton liquids with relatively low viscosities.While in some industrial processes,such as spray drying,liquids to be atomized are high concentration suspensions or non-Newtonian fluids with high viscosities.In this paper,non-Newtonian fluids with viscosity up to 4.4 Pa·s were effectively atomized using a specially designed prefilming airblast atomizer.The atomizer enabled liquid to extend to a thickness-adjustable film and forced the atomizing air stream to swirl with 30° or 45° through gas distributors with spiral slots.The liquid film was impinged by the swirling air stream resulting in the disintegration of the film into drops.Drop sizes were measured using a laser diffraction technique.An improved four-parameter mathematical model was established to relate the Sauter mean diameter of drops to the atomization conditions in terms of power dependencies on three dimensionless groups:Weber number,Ohnesorge number and air liquid mass ratio.The friction on the surface of the liquid film made by swirling air stream played an important role in the prefilming atomization at the conditions of low air velocity and low liquid viscosity.In this case,the liquid film was disintegrated into drops according to the classical wavy-sheet mechanism,thus thinner liquid films and high swirl levels of the atomizing air produced smaller drops.With the increase of the air velocity and the liquid viscosity,the effect of the friction on the prefilming atomization relatively weakened,whereas the impingement on the liquid film made by atomizing air stream in a direction normal to the liquid film and corresponding momentum transfer gradually strengthened and eventually dominated the disruption of liquid into drops,which induced that the initial thickness of the liquid film and the swirl of atomizing air stream exercised a minor influence on the drop sizes.展开更多
This paper presents experimental and numerical studies on spray painting processes by using airless spray guns for ship painting. A computational fluid dynamics code was applied to calculate the flow field and the dro...This paper presents experimental and numerical studies on spray painting processes by using airless spray guns for ship painting. A computational fluid dynamics code was applied to calculate the flow field and the droplet trajectories. Droplet size distributions and droplet velocities as necessary inlet characteristics for the simulations were experimentally obtained using a Spraytec Fraunhofer type particle sizer and laser-Doppler anemometry. Effects of shoreline winds and painting distance on the transfer efficiency and on the paint film thickness distributions on the target were numerically studied.展开更多
基金The Key Foundation Research Project (G1999016001) of China and the Japan International Cooperation Agency
文摘Three steam distillation devices (D-1, D-2 and D-4) or one simultaneous distillation (D-3, water-diethyl ether) as well as the process of CO2-SFE (Supercritical fluid extraction) were adopted in extraction of essential oils from Chinese-fir (Cunninghamia lancedata (Lamb) Hook.) and the chemical components of the extracted essential oil were analyzed by Gas chromatograph-MS analyses. The results showed that the essential oil could be almost extracted out within 2 hours and the device-3 had the highest extraction efficiency. The major chemical component of the oil was cedrol. The yield of the extracted essential oils from Chinese fir decreased gradually with the increase of the distillation time. The best condition for extraction by means of CO2-SFE is 100 kg·cm?2 in pressure and 40°C in temperature for. Keywords Chinese fir - Essential oil - Cedrol - Supercritical fluid extraction CLC number S781.4 Document code A Foundation item: This paper was support by the Key Foundation Research Project (G1999016001) of China and the Japan International Cooperation AgencyBiography: HUANG Luo-hua (1957-), male, Research associate, Research Institute of Wood Industry, Chinese Academy of forestry, Beijing 100091, P. R. ChinaResponsible editor: Song Funan
基金Supported by the National Natural Science Foundation of China（10871159） the National Basic Research Program of China（2005CB321704）
文摘A non-isothermal injection molding process for a non-Newtonian viscous pseudoplastic fluid is simulated.A conservative interface capturing technique and the flow field solving method are coupled to perform a dynamic simulation.The validity of the numerical method is verified by a benchmark problem.The melt interface evolution versus time is captured and the physical quantities such as temperature,velocity and pressure at each time step are obtained with corresponding analysis.A"frozen skin"layer with the thickness increasing versus time during the injection process is found.The fact that the"frozen skin"layer can be reduced by increasing the injection velocity is numerically verified.The fountain flow phenomenon near the melt interface is also captured.Moreover,comparisons with the non-isothermal Newtonian case show that the curvatures of the interface arcs and the pressure contours near the horizontal mid-line of the cavity for the non-Newtonian pseudoplastic case is larger than that for the Newtonian case.The velocity profiles are different at different positions for the non-Newtonian pseudoplastic case,while in the case of Newtonian flow the velocity profiles are parabolic and almost the same at different positions.
文摘The rotating pipe fluid in the crossed electric and magnetic field not only suffered the forces in the steady condition, but also suffered Coriolis force, centrifugal force because of rotation and electromagnetic volume force. The motion equation of fluid and the hydrokinetics equations of rotating pipe were described in the Cartesians coordinates. The equations showed that the solutions to hydrokinetics equations of rotating pipe in the crossed electric and magnetic electromagnetic field were highly complicated and numerical calculations were also astronomical. The pressure distribution and temperature distribution of one dimension were solved using the electromagnetic equations set. The results showed that the fluid in rotating pipe was in the asymmetrical pressure field and temperature field because it was in the energy exchange and thermo-electrical coupling course. The primary characteristic of flow course could be expressed using the proposed hydrokinetics equations.
文摘Liquids to be broken up using a prefilming airblast atomizer are usually Newton liquids with relatively low viscosities.While in some industrial processes,such as spray drying,liquids to be atomized are high concentration suspensions or non-Newtonian fluids with high viscosities.In this paper,non-Newtonian fluids with viscosity up to 4.4 Pa·s were effectively atomized using a specially designed prefilming airblast atomizer.The atomizer enabled liquid to extend to a thickness-adjustable film and forced the atomizing air stream to swirl with 30° or 45° through gas distributors with spiral slots.The liquid film was impinged by the swirling air stream resulting in the disintegration of the film into drops.Drop sizes were measured using a laser diffraction technique.An improved four-parameter mathematical model was established to relate the Sauter mean diameter of drops to the atomization conditions in terms of power dependencies on three dimensionless groups:Weber number,Ohnesorge number and air liquid mass ratio.The friction on the surface of the liquid film made by swirling air stream played an important role in the prefilming atomization at the conditions of low air velocity and low liquid viscosity.In this case,the liquid film was disintegrated into drops according to the classical wavy-sheet mechanism,thus thinner liquid films and high swirl levels of the atomizing air produced smaller drops.With the increase of the air velocity and the liquid viscosity,the effect of the friction on the prefilming atomization relatively weakened,whereas the impingement on the liquid film made by atomizing air stream in a direction normal to the liquid film and corresponding momentum transfer gradually strengthened and eventually dominated the disruption of liquid into drops,which induced that the initial thickness of the liquid film and the swirl of atomizing air stream exercised a minor influence on the drop sizes.
文摘This paper presents experimental and numerical studies on spray painting processes by using airless spray guns for ship painting. A computational fluid dynamics code was applied to calculate the flow field and the droplet trajectories. Droplet size distributions and droplet velocities as necessary inlet characteristics for the simulations were experimentally obtained using a Spraytec Fraunhofer type particle sizer and laser-Doppler anemometry. Effects of shoreline winds and painting distance on the transfer efficiency and on the paint film thickness distributions on the target were numerically studied.
