Numerical simulation of enhanced fluid flow characteristics in a three-stage double-stirring extraction tank was conducted with the coupling of an Eulerian multiphase flow model and a Morsi-Alexander interphase drag f...Numerical simulation of enhanced fluid flow characteristics in a three-stage double-stirring extraction tank was conducted with the coupling of an Eulerian multiphase flow model and a Morsi-Alexander interphase drag force model. Results show that the addition of a stirring device into the settler can efficiently reduce the volume fraction of out-of-phase impurity in the outlet, and accelerate the settling separation of oil-water mixture. Such addition can also effectively break down the oil-water-wrapped liquid droplets coming from the mixer, inhibit reflux from the outlet, and improve the oil-water separation. The addition of a stirring device induces ignorable power consumption compared with that by the mixer, and can thus facilitate the commercialized promotion of this novel equipment.展开更多
The paper described experimental investigation of heat transfer and single-phase pressure drop through tubes with different rotor-assembled strands inserted in the Reynolds number range of 800-9000 with lubricant as w...The paper described experimental investigation of heat transfer and single-phase pressure drop through tubes with different rotor-assembled strands inserted in the Reynolds number range of 800-9000 with lubricant as working fluid. In the experiment, fixed mounts were employed to eliminate the entrance effect. The experimental results showed that the employment of fixed mounts led to a visible bias of friction factor in the laminar regime while it could not affect the Nusselt numbers significantly. Experiment for the tube inserted with rotors-assembled strand showed remarkable improvement for heat transfer with the Nusselt number increased by 200%-225% in the laminar regime and 125%-160% in the transitional regime. Meanwhile, the friction factor increased inevitably by 200%-300% within the same range of Reynolds number. The comparison of different rotor-assembled strands in-serted tubes and plain tube showed that the heat transfer benefited from the increase of the diameter of rotor-assembled strand with the same lead and the decrease of the lead of rotor-assembled strand, so does the friction factor. Based on experimental data and thorough multivariant linear normal regression method, the correlations of average Nusselt number and friction factor are established.展开更多
The existing oil import dependence index cannot exactly measure the economic cost or scales, and it is difficult to describe the economical aspect of oil security. To measure the foreign dependence of one country'...The existing oil import dependence index cannot exactly measure the economic cost or scales, and it is difficult to describe the economical aspect of oil security. To measure the foreign dependence of one country's economy and reflect its oil economic security, this paper defines the net oil import intensity as the ratio of net oil import cost to GDP. By using Divisia Index Decomposition, the change of net oil import intensity in five industrialized countries and five newly industrialized countries during 1971—2010 is decomposed into five factors: oil price, oil intensity, oil self-sufficiency, domestic price level and exchange rate. The result shows that the dominating factors are oil price and oil intensity; moreover, the newly industrialized countries have higher net oil import intensity than industrialized countries.展开更多
The main aim of this study was to explore the effects of microwave pre-treatment on quality of kenaf seed oil by observing the changes in oil yield, oxidative stability, fatty acid components, tocopherols, antioxidant...The main aim of this study was to explore the effects of microwave pre-treatment on quality of kenaf seed oil by observing the changes in oil yield, oxidative stability, fatty acid components, tocopherols, antioxidant activities and color intensity of kenaf seed oil. Microwave pre-treatment on kenaf seeds did affect the quality of the extracted oils. Microwave pre-treatment increased the extracted oil yields significantly （P 〈 0.05）. Moreover, the roasted oils showed a significant increase in oxidative stability, antioxidant stability and colour of kenaf seed oils. In terms of fatty acids composition, microwave roasting had greater effect on oleic acids （C18：1） and linoleic acids （C18：2）, as roasting increased the oleic acid content but decreased linoleic acid. There was no significant difference in the palmitic acids （C16：0） and stearic acids （C18：0） （P 〉 0.05）. A significant decrease （P 〈 0.05） in the iodine value of the oils was found. In conclusion, kenaf seed oil roasted for 2 min had better oil quality if compared to the unroasted oil, as microwave pre-treatment improved the oil yield, oxidative stability and antioxidant activities of kenaf seed oil.展开更多
基金financially supported by the National 863 Plan(2010AA03A405and 2012AA062303)+4 种基金the National 973 Plan(2012CBA01205)the National Natural Science Foundation of China(U120227451204040)the National Science and Technology Support Program(2012BAE01B02)the Fundamental Research Funds for the Central Universities(N130702001 and N130607001)
文摘Numerical simulation of enhanced fluid flow characteristics in a three-stage double-stirring extraction tank was conducted with the coupling of an Eulerian multiphase flow model and a Morsi-Alexander interphase drag force model. Results show that the addition of a stirring device into the settler can efficiently reduce the volume fraction of out-of-phase impurity in the outlet, and accelerate the settling separation of oil-water mixture. Such addition can also effectively break down the oil-water-wrapped liquid droplets coming from the mixer, inhibit reflux from the outlet, and improve the oil-water separation. The addition of a stirring device induces ignorable power consumption compared with that by the mixer, and can thus facilitate the commercialized promotion of this novel equipment.
基金Supported by the National Natural Science Foundation of Beijing （3102023） and the National Science and Technology Support Plan Project （2011BAA04B02）.
文摘The paper described experimental investigation of heat transfer and single-phase pressure drop through tubes with different rotor-assembled strands inserted in the Reynolds number range of 800-9000 with lubricant as working fluid. In the experiment, fixed mounts were employed to eliminate the entrance effect. The experimental results showed that the employment of fixed mounts led to a visible bias of friction factor in the laminar regime while it could not affect the Nusselt numbers significantly. Experiment for the tube inserted with rotors-assembled strand showed remarkable improvement for heat transfer with the Nusselt number increased by 200%-225% in the laminar regime and 125%-160% in the transitional regime. Meanwhile, the friction factor increased inevitably by 200%-300% within the same range of Reynolds number. The comparison of different rotor-assembled strands in-serted tubes and plain tube showed that the heat transfer benefited from the increase of the diameter of rotor-assembled strand with the same lead and the decrease of the lead of rotor-assembled strand, so does the friction factor. Based on experimental data and thorough multivariant linear normal regression method, the correlations of average Nusselt number and friction factor are established.
基金Supported by the National Natural Science Foundation of China(No.71273027 and No.71322306)
文摘The existing oil import dependence index cannot exactly measure the economic cost or scales, and it is difficult to describe the economical aspect of oil security. To measure the foreign dependence of one country's economy and reflect its oil economic security, this paper defines the net oil import intensity as the ratio of net oil import cost to GDP. By using Divisia Index Decomposition, the change of net oil import intensity in five industrialized countries and five newly industrialized countries during 1971—2010 is decomposed into five factors: oil price, oil intensity, oil self-sufficiency, domestic price level and exchange rate. The result shows that the dominating factors are oil price and oil intensity; moreover, the newly industrialized countries have higher net oil import intensity than industrialized countries.
文摘The main aim of this study was to explore the effects of microwave pre-treatment on quality of kenaf seed oil by observing the changes in oil yield, oxidative stability, fatty acid components, tocopherols, antioxidant activities and color intensity of kenaf seed oil. Microwave pre-treatment on kenaf seeds did affect the quality of the extracted oils. Microwave pre-treatment increased the extracted oil yields significantly （P 〈 0.05）. Moreover, the roasted oils showed a significant increase in oxidative stability, antioxidant stability and colour of kenaf seed oils. In terms of fatty acids composition, microwave roasting had greater effect on oleic acids （C18：1） and linoleic acids （C18：2）, as roasting increased the oleic acid content but decreased linoleic acid. There was no significant difference in the palmitic acids （C16：0） and stearic acids （C18：0） （P 〉 0.05）. A significant decrease （P 〈 0.05） in the iodine value of the oils was found. In conclusion, kenaf seed oil roasted for 2 min had better oil quality if compared to the unroasted oil, as microwave pre-treatment improved the oil yield, oxidative stability and antioxidant activities of kenaf seed oil.
