Liquid foam is a dense packing of gas bubbles in a small amount of liquid containing surfactants or other surface-active macromolecules, which is one of the highly organized materials and possesses hallmark rheologica...Liquid foam is a dense packing of gas bubbles in a small amount of liquid containing surfactants or other surface-active macromolecules, which is one of the highly organized materials and possesses hallmark rheological behaviour of soft matters. Forced foam drainage is the flow of constantly inputted liquid through the network of interstitial channels between bubbles under actions of gravity and capil-larity. This process involves two mechanisms: minimal viscous flow dissipation of liquid and minimal surface energy of bubbles. For constant surfactant solution, viscous dissipation usually varies with gravity. This work reports simulations of 2D forced foam drainage with narrow input in a Hele-Shaw cell under 8 different gravities, g, ranging from 9.8 to 0 ms?2. The spread of liquid both vertical due to gravity action, and horizontal due to capillary suction, is recorded over time. Positions of drainage wave fronts in both directions with time are found to be well described in the power law form, and the exponents are 0.536+5.29×10-3g and 0.479?7.27×10-3g, respectively, while the sum is close to a constant of 1.015 which is independent of gravity. For g=9.8 ms-2, the calculated exponents are in good agreement with experimental results by Hutzler et al. and Wang.展开更多
The velocity field in a single Plateau border（PB） of the aluminum foam in the drainage process is studied using a mathematical model for the flow inside a microchannel.We show that the liquid/gas interface mobility ...The velocity field in a single Plateau border（PB） of the aluminum foam in the drainage process is studied using a mathematical model for the flow inside a microchannel.We show that the liquid/gas interface mobility characterized by the Newtonian surface viscosity has a substantial effect on the velocity inside the single PB.With the same liquid/gas interfacial mobility and the same radius of the curvature,the maximum velocity inside an exterior PB is about 6～8 times as large as that inside an interior PB.We also find a critical value of the interfacial mobility in the interior PB.For the values greater and less than this critical value,the effects of the film thickness on the velocity in the PB show opposite tendencies.Based on the multiscale methodology,with the coupling between the microscale and the macroscale and the results obtained from the microscopical model,a simplified macroscopical drainage model is presented for the aluminum foams.The comparisons among the computational results obtained from the present model,the experimental data quoted in the literature,and the results of the classical drainage equation show a reasonable agreement.The computational results reveal that the liquid holdup of the foams is strongly dependent on the value of the mobility and the bubble radius.展开更多
Liquid foam is a dense random packing of gas or liquid bubbles in a small amount of immiscible liquid containing surfactants. The liquid within the Plateau borders, although small in volume, causes considerable diffic...Liquid foam is a dense random packing of gas or liquid bubbles in a small amount of immiscible liquid containing surfactants. The liquid within the Plateau borders, although small in volume, causes considerable difficulties to the investigation of the spatial structure and physical properties of foams, and the situation becomes even more com-plicated as the fluid flows. To solve these problems, a discrete model of two-dimensional liquid foams on the bubble scale is proposed in this work. The bubble surface is represented with finite number of nodes, and the liquid within Plateau borders is discretized into lattice particles. The gas in bubbles is treated as ideal gas at constant temperatures. This model is tested by choosing an arbitrary shape bubble as the initial condition. This then automatically evolves into a cir-cular shape, which indicates that the surface energy minimum routine is obeyed without calling external controlling con-ditions. Without inserting liquid particle among the bubble channels, periodic ordered and disordered dry foams are both simulated, and the fine foam structures are developed. Wet foams are also simulated by inserting fluid among bubble channels. The calculated coordination number, as a function of liquid fractions, agrees well with the standard values.展开更多
The foam fractionation of nisin from its fermentation broth was studied.Two types of devices consisting of a rubber piston and a foam riser were developed to enhance foam drainage.The separation performance of these t...The foam fractionation of nisin from its fermentation broth was studied.Two types of devices consisting of a rubber piston and a foam riser were developed to enhance foam drainage.The separation performance of these two devices was investigated.Experimental results indicated that the second device could significantly reduce the liquid fraction of the foam leaving the column,εout,leading to a higher enrichment of the out-flow stream.As its mounting height increased from 0 to 15 cm,εout declined from 7.07‰ to 6.13 ‰ and the maximum nisin activity in the foamate could reach 39.6 IU/μL.The slight increase in nisin inactivation rate indicated the applicability of this method in the recovery and concentration of proteins.Finally,the mechanism of the process was primarily explained by invoking recent work on pneumatic foams.This research provides a basis for the design of multistage draining foam fractionator which could potentially be an effective separation equipment.展开更多
Liquid foam is a dense packing of gas bubbles in a small amount of surfactant solution. Liquid drains out of foams until equilibrium is reached due to the compromise between gravity and capillarity, which greatly affe...Liquid foam is a dense packing of gas bubbles in a small amount of surfactant solution. Liquid drains out of foams until equilibrium is reached due to the compromise between gravity and capillarity, which greatly affects the stability of foam. Based on a series of work on foam structure and drainage we conducted previously, this paper reports the results on coalescence of an original forced drainage wave at a low flow rate with subsequent drainage waves with higher flow rates. The evolutions of viscous energy and surface energy during the process of coalescence are theoretically analyzed.展开更多
To get a deeper understanding on the synergistic enhancement effect of low frequency artificial seismic wave on foam stability,a micro-kinetic model of enhanced foam stability under low frequency artificial seismic wa...To get a deeper understanding on the synergistic enhancement effect of low frequency artificial seismic wave on foam stability,a micro-kinetic model of enhanced foam stability under low frequency artificial seismic wave is established based on a vertical liquid film drainage model and elastic wave theory.The model is solved by non-dimensional transformation of the high order partial differential equations and a compound solution of implicit and explicit differences and is verified to be accurate.The foam film thickness,surfactant concentration distribution and drainage velocity under the action of low frequency artificial seismic wave are quantitatively analyzed.The research shows that low-frequency vibration can reduce the difference between the maximum and minimum concentrations of surfactant in the foam liquid film at the later stage of drainage,enhance the effect of Marangoni effect,and improve the stability of the foam liquid film.When the vibration frequency is close to the natural frequency of the foam liquid film,the vibration effect is the best,and the best vibration frequency is about 50 Hz.The higher the vibration acceleration,the faster the recovery rate of surfactant concentration in the foam liquid film is.The higher the vibration acceleration,the stronger the ability of Marangoni effect to delay the drainage of foam liquid film and the better the foam stability is.It is not the higher the vibration acceleration,the better.The best vibration acceleration is about 0.5 times of gravity acceleration.Reasonable vibration parameters would greatly enhance the effect of Marangoni effect.The smaller the initial concentration of surfactant,the better the vibration works in enhancing Marangoni effect.展开更多
以3-氯-2-羟基丙烷磺酸钠、油酸酰胺丙基二甲基叔胺、1,2-二溴乙烷为原料合成了甜菜碱Gemini表面活性剂(简称M-66),采用FTIR,~1H NMR,ESI-MS方法对其结构进行了表征,并测得25℃时M-66的表面张力和临界胶束浓度分别为28.22 m N/m和3.8...以3-氯-2-羟基丙烷磺酸钠、油酸酰胺丙基二甲基叔胺、1,2-二溴乙烷为原料合成了甜菜碱Gemini表面活性剂(简称M-66),采用FTIR,~1H NMR,ESI-MS方法对其结构进行了表征,并测得25℃时M-66的表面张力和临界胶束浓度分别为28.22 m N/m和3.8×10^(-6) mol/L;考察了M-66的起泡性能和综合携液性能,且与常用油田助剂椰子油脂肪酸二乙醇酰胺、十六烷基三甲基氯化铵、十二烷基硫酸钠和月桂基羟乙基咪唑啉进行了对比。实验结果表明,M-66表现出较好的起泡性能和综合携液性能;在清水、250 000 mg/L矿化度的矿化水、20%(φ)甲醇溶液、30%(φ)凝析油-水混合液的条件下,M-66携液率最高分别达89%,65%,85%,59%,表现出良好的抗盐、抗甲醇、抗凝析油性能,且与十六烷基三甲基氯化铵复配携液性能更优。展开更多
基金the National Natural Science Foundation of China (Grant No. 20336040)the Scientific Research Foundation of the State Human Resource Ministry for Returned Chinese Scholars
文摘Liquid foam is a dense packing of gas bubbles in a small amount of liquid containing surfactants or other surface-active macromolecules, which is one of the highly organized materials and possesses hallmark rheological behaviour of soft matters. Forced foam drainage is the flow of constantly inputted liquid through the network of interstitial channels between bubbles under actions of gravity and capil-larity. This process involves two mechanisms: minimal viscous flow dissipation of liquid and minimal surface energy of bubbles. For constant surfactant solution, viscous dissipation usually varies with gravity. This work reports simulations of 2D forced foam drainage with narrow input in a Hele-Shaw cell under 8 different gravities, g, ranging from 9.8 to 0 ms?2. The spread of liquid both vertical due to gravity action, and horizontal due to capillary suction, is recorded over time. Positions of drainage wave fronts in both directions with time are found to be well described in the power law form, and the exponents are 0.536+5.29×10-3g and 0.479?7.27×10-3g, respectively, while the sum is close to a constant of 1.015 which is independent of gravity. For g=9.8 ms-2, the calculated exponents are in good agreement with experimental results by Hutzler et al. and Wang.
基金Project supported by the National Natural Science Foundation of China(No.50876017)
文摘The velocity field in a single Plateau border（PB） of the aluminum foam in the drainage process is studied using a mathematical model for the flow inside a microchannel.We show that the liquid/gas interface mobility characterized by the Newtonian surface viscosity has a substantial effect on the velocity inside the single PB.With the same liquid/gas interfacial mobility and the same radius of the curvature,the maximum velocity inside an exterior PB is about 6～8 times as large as that inside an interior PB.We also find a critical value of the interfacial mobility in the interior PB.For the values greater and less than this critical value,the effects of the film thickness on the velocity in the PB show opposite tendencies.Based on the multiscale methodology,with the coupling between the microscale and the macroscale and the results obtained from the microscopical model,a simplified macroscopical drainage model is presented for the aluminum foams.The comparisons among the computational results obtained from the present model,the experimental data quoted in the literature,and the results of the classical drainage equation show a reasonable agreement.The computational results reveal that the liquid holdup of the foams is strongly dependent on the value of the mobility and the bubble radius.
文摘Liquid foam is a dense random packing of gas or liquid bubbles in a small amount of immiscible liquid containing surfactants. The liquid within the Plateau borders, although small in volume, causes considerable difficulties to the investigation of the spatial structure and physical properties of foams, and the situation becomes even more com-plicated as the fluid flows. To solve these problems, a discrete model of two-dimensional liquid foams on the bubble scale is proposed in this work. The bubble surface is represented with finite number of nodes, and the liquid within Plateau borders is discretized into lattice particles. The gas in bubbles is treated as ideal gas at constant temperatures. This model is tested by choosing an arbitrary shape bubble as the initial condition. This then automatically evolves into a cir-cular shape, which indicates that the surface energy minimum routine is obeyed without calling external controlling con-ditions. Without inserting liquid particle among the bubble channels, periodic ordered and disordered dry foams are both simulated, and the fine foam structures are developed. Wet foams are also simulated by inserting fluid among bubble channels. The calculated coordination number, as a function of liquid fractions, agrees well with the standard values.
基金supported by Natural Science Foundation of Tianjin (Grant No. 08JCZDJC25200)Natural Science Research Program of Hebei Province (Grant No. Z2008310)
文摘The foam fractionation of nisin from its fermentation broth was studied.Two types of devices consisting of a rubber piston and a foam riser were developed to enhance foam drainage.The separation performance of these two devices was investigated.Experimental results indicated that the second device could significantly reduce the liquid fraction of the foam leaving the column,εout,leading to a higher enrichment of the out-flow stream.As its mounting height increased from 0 to 15 cm,εout declined from 7.07‰ to 6.13 ‰ and the maximum nisin activity in the foamate could reach 39.6 IU/μL.The slight increase in nisin inactivation rate indicated the applicability of this method in the recovery and concentration of proteins.Finally,the mechanism of the process was primarily explained by invoking recent work on pneumatic foams.This research provides a basis for the design of multistage draining foam fractionator which could potentially be an effective separation equipment.
基金the National Natural Science Foundation of China (Grant No.20776142)
文摘Liquid foam is a dense packing of gas bubbles in a small amount of surfactant solution. Liquid drains out of foams until equilibrium is reached due to the compromise between gravity and capillarity, which greatly affects the stability of foam. Based on a series of work on foam structure and drainage we conducted previously, this paper reports the results on coalescence of an original forced drainage wave at a low flow rate with subsequent drainage waves with higher flow rates. The evolutions of viscous energy and surface energy during the process of coalescence are theoretically analyzed.
基金Supported by National Natural Science Foundation of China(51904320,51874339)The Special Fundamental Research Fund for the Central Universities(18CX02095A)。
文摘To get a deeper understanding on the synergistic enhancement effect of low frequency artificial seismic wave on foam stability,a micro-kinetic model of enhanced foam stability under low frequency artificial seismic wave is established based on a vertical liquid film drainage model and elastic wave theory.The model is solved by non-dimensional transformation of the high order partial differential equations and a compound solution of implicit and explicit differences and is verified to be accurate.The foam film thickness,surfactant concentration distribution and drainage velocity under the action of low frequency artificial seismic wave are quantitatively analyzed.The research shows that low-frequency vibration can reduce the difference between the maximum and minimum concentrations of surfactant in the foam liquid film at the later stage of drainage,enhance the effect of Marangoni effect,and improve the stability of the foam liquid film.When the vibration frequency is close to the natural frequency of the foam liquid film,the vibration effect is the best,and the best vibration frequency is about 50 Hz.The higher the vibration acceleration,the faster the recovery rate of surfactant concentration in the foam liquid film is.The higher the vibration acceleration,the stronger the ability of Marangoni effect to delay the drainage of foam liquid film and the better the foam stability is.It is not the higher the vibration acceleration,the better.The best vibration acceleration is about 0.5 times of gravity acceleration.Reasonable vibration parameters would greatly enhance the effect of Marangoni effect.The smaller the initial concentration of surfactant,the better the vibration works in enhancing Marangoni effect.
