The dependence of starting materials and their initial grain sizes on the formation of gases （H2, CH4, C2H6 and C3Hs） during serpentinization was investigated by conducting hydrothermal experiments at 311℃ and 3 kb...The dependence of starting materials and their initial grain sizes on the formation of gases （H2, CH4, C2H6 and C3Hs） during serpentinization was investigated by conducting hydrothermal experiments at 311℃ and 3 kbar on olivine and peridotite with initial grain sizes ranging from 〈30 to 177 μm. Hydrocarbons （CH4, C2H6 and C3H8） were produced from reaction between dissolved CO2 in the starting fluids and HE formed during serpentinization, which were analyzed by Gas Chromatography. It was found that olivine serpentinization produced much less H2 and CH4 compared with those after peridotite alteration, while their C2H6 and C3H8 were identical. For example, for olivine with initial grain sizes of 〈30 μm, the amounts of HE and CH4 were 79.6 mmol/kg and 460 μmol/kg after 27 days, respectively. By contrast, the quantities of H2 and CH4 produced in experiment on peridotite with the same run duration were much larger, 119 mmol/kg and 1300 μmol/kg, respectively. This indicates that spinel and pyroxene in peridotite may increase the amounts of HE and hydrocarbons, possibly due to the catalytic effect of aluminum released by spinel and pyroxene during serpentinization. Moreover, the production of H2 and hydrocarbons is negatively correlated with initial grain sizes of the starting material, with smaller amounts of HE and hydrocarbons for larger initial grain sizes, indicating that the kinetics of serpentinization influences the formation of HE and hydrocarbons, possibly because of the lack of catalytic minerals for the starting material with larger grain sizes. This study suggests that olivine cannot completely represent peridotite during serpentinization, and that H2 and hydrocarbons in hydrothermal fields near the mid-ocean ridge may be produced in a very long period of serpentinization or the presence of catalytic minerals due to large grain sizes of ultramafic rocks.展开更多
Gas–liquid flow in serpentine microchannel with different surface properties exhibits drastically different flow behavior. With water and air as working fluids, the method of numerical simulation was adopted in this ...Gas–liquid flow in serpentine microchannel with different surface properties exhibits drastically different flow behavior. With water and air as working fluids, the method of numerical simulation was adopted in this paper based on CLSVOF(coupled level set and volume of fluid method) multiphase model. After verifying the reasonability of the model through experiment, by changing wall properties and Re number(Re<1500), the influences of contact angle and surface roughness on flow regime and Po number were discussed. Moreover, the difference of pressure drop between curve and straight microchannel was also calculated. Beyond that, the combined effect of curve channel and wall properties on flow resistance was analyzed. This paper finds that wall properties have great influence on gas–liquid flow in microchannels not only on flow regime but also flow characteristics. Meanwhile, the pressure drop in curve microchannels is larger than straight. It is more beneficial for fluid flowing when the straight part of microchannel is hydrophilic smooth wall and curve part is hydrophobic with large roughness.展开更多
采用CLSVOF(coupled level set and volume of fluid)方法,以空气和水为工作流体对小曲率矩形截面蛇形微通道内气液两相流动进行模拟研究。验证模型的合理性后,研究了曲率对弯通道内压降的影响,曲率及气相速度对弹状流气泡及液塞长度的...采用CLSVOF(coupled level set and volume of fluid)方法,以空气和水为工作流体对小曲率矩形截面蛇形微通道内气液两相流动进行模拟研究。验证模型的合理性后,研究了曲率对弯通道内压降的影响,曲率及气相速度对弹状流气泡及液塞长度的综合影响;同时深入分析了弯管内气液两相流动的传质特性,包括不同曲率下气泡长度的变化,弯管内液侧体积传质系数与液膜体积传质系数的比较,曲率及气相速度对液相体积传质系数的影响。同时,对比了回转弯道与直微通道传质系数的差异,发现弯微通道可以强化传质。展开更多
采用CLSVOF(coupled level set and volume of fluid)方法,以空气和水为介质对矩形截面蛇形微通道内气液两相流动进行模拟研究。验证模型的合理性后,系统地研究了表面张力,液相黏度,壁面接触角及通道截面形状对蛇形微通道内不同流型间...采用CLSVOF(coupled level set and volume of fluid)方法,以空气和水为介质对矩形截面蛇形微通道内气液两相流动进行模拟研究。验证模型的合理性后,系统地研究了表面张力,液相黏度,壁面接触角及通道截面形状对蛇形微通道内不同流型间转换界限的影响,并绘制了不同表面张力、液相黏度及接触角下的流型图。最后,将计算结果与相同当量直径不同截面微通道内两相流流型图进行对比,分析截面形状及高宽比对流型间转换界限的影响。这些基本规律为微通道的系统设计提供了一定依据。展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.4109037341121002+2 种基金41103012 and 41173069)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB06030100)also by Postdoctoral Science Foundation of China(Grant No.2015M570735)
文摘The dependence of starting materials and their initial grain sizes on the formation of gases （H2, CH4, C2H6 and C3Hs） during serpentinization was investigated by conducting hydrothermal experiments at 311℃ and 3 kbar on olivine and peridotite with initial grain sizes ranging from 〈30 to 177 μm. Hydrocarbons （CH4, C2H6 and C3H8） were produced from reaction between dissolved CO2 in the starting fluids and HE formed during serpentinization, which were analyzed by Gas Chromatography. It was found that olivine serpentinization produced much less H2 and CH4 compared with those after peridotite alteration, while their C2H6 and C3H8 were identical. For example, for olivine with initial grain sizes of 〈30 μm, the amounts of HE and CH4 were 79.6 mmol/kg and 460 μmol/kg after 27 days, respectively. By contrast, the quantities of H2 and CH4 produced in experiment on peridotite with the same run duration were much larger, 119 mmol/kg and 1300 μmol/kg, respectively. This indicates that spinel and pyroxene in peridotite may increase the amounts of HE and hydrocarbons, possibly due to the catalytic effect of aluminum released by spinel and pyroxene during serpentinization. Moreover, the production of H2 and hydrocarbons is negatively correlated with initial grain sizes of the starting material, with smaller amounts of HE and hydrocarbons for larger initial grain sizes, indicating that the kinetics of serpentinization influences the formation of HE and hydrocarbons, possibly because of the lack of catalytic minerals for the starting material with larger grain sizes. This study suggests that olivine cannot completely represent peridotite during serpentinization, and that H2 and hydrocarbons in hydrothermal fields near the mid-ocean ridge may be produced in a very long period of serpentinization or the presence of catalytic minerals due to large grain sizes of ultramafic rocks.
文摘Gas–liquid flow in serpentine microchannel with different surface properties exhibits drastically different flow behavior. With water and air as working fluids, the method of numerical simulation was adopted in this paper based on CLSVOF(coupled level set and volume of fluid method) multiphase model. After verifying the reasonability of the model through experiment, by changing wall properties and Re number(Re<1500), the influences of contact angle and surface roughness on flow regime and Po number were discussed. Moreover, the difference of pressure drop between curve and straight microchannel was also calculated. Beyond that, the combined effect of curve channel and wall properties on flow resistance was analyzed. This paper finds that wall properties have great influence on gas–liquid flow in microchannels not only on flow regime but also flow characteristics. Meanwhile, the pressure drop in curve microchannels is larger than straight. It is more beneficial for fluid flowing when the straight part of microchannel is hydrophilic smooth wall and curve part is hydrophobic with large roughness.
文摘采用CLSVOF(coupled level set and volume of fluid)方法,以空气和水为工作流体对小曲率矩形截面蛇形微通道内气液两相流动进行模拟研究。验证模型的合理性后,研究了曲率对弯通道内压降的影响,曲率及气相速度对弹状流气泡及液塞长度的综合影响;同时深入分析了弯管内气液两相流动的传质特性,包括不同曲率下气泡长度的变化,弯管内液侧体积传质系数与液膜体积传质系数的比较,曲率及气相速度对液相体积传质系数的影响。同时,对比了回转弯道与直微通道传质系数的差异,发现弯微通道可以强化传质。
文摘采用CLSVOF(coupled level set and volume of fluid)方法,以空气和水为介质对矩形截面蛇形微通道内气液两相流动进行模拟研究。验证模型的合理性后,系统地研究了表面张力,液相黏度,壁面接触角及通道截面形状对蛇形微通道内不同流型间转换界限的影响,并绘制了不同表面张力、液相黏度及接触角下的流型图。最后,将计算结果与相同当量直径不同截面微通道内两相流流型图进行对比,分析截面形状及高宽比对流型间转换界限的影响。这些基本规律为微通道的系统设计提供了一定依据。
