The accurate prediction of the droplet size distribution(DSD)in liquid–liquid turbulent dispersions is of fundamental importance in many industrial applications and it requires suitable kernels in the population bala...The accurate prediction of the droplet size distribution(DSD)in liquid–liquid turbulent dispersions is of fundamental importance in many industrial applications and it requires suitable kernels in the population balance model.When a surfactant is included in liquid–liquid dispersions,the droplet breakup behavior will change as an effect of the reduction of the interfacial tension.Moreover,also the dynamic interfacial tension may be different with respect to the static,due to the fact that the surfactant may be easily desorbed from the droplet surface,generating additional disruptive stresses.In this work,the performance of five breakup kernels from the literature is assessed,to investigate their ability to predict the time evolution of the DSD and of the mean Sauter diameter,when different surfactants are employed.Simulations are performed with the Quadrature Method of Moments for the solution of the population balance model coupled with the two-fluid model implemented in the compressible Two Phase Euler Foam solver of the open-source computational fluid dynamics(CFD)code Open FOAM v.2.2.x.The time evolution of the mean Sauter diameter predicted by these kernels is validated against experimental data for six test cases referring to a stirred tank with different types of surfactants(Tween 20 and PVA 88%)at different concentrations operating under different stirrer rates.Our results show that for the dispersion containing Tween 20 additional stress is generated,the multifractal breakup kernel properly predicts the DSD evolution,whereas two other kernels predict too fast breakup of droplets covered by adsorbed PVA.Kernels derived originally for bubbles completely fail.展开更多
Steady-state model of a high-temperature solid oxide fuel cell （SOFC） is considered, which refers to constant chemical potentials of incoming hydrogen fuel and oxidant. Lowering of the cell voltage below its reversi...Steady-state model of a high-temperature solid oxide fuel cell （SOFC） is considered, which refers to constant chemical potentials of incoming hydrogen fuel and oxidant. Lowering of the cell voltage below its reversible value is attributed to polarizations and imperfect conversions of reactions. An imperfect power formula summarizes the effect of transport laws, irreversible polarizations and efficiency of power yield. Reversible electrochemical theory is extended to the case with dissipative chemical reactions; this case includes systems with incomplete conversions, characterized by ＂reduced affinities＂ and an idle run voltage. Efficiency drop is linked with thermodynamic and electrochemical irreversibilities expressed in terms of polarizations （activation, concentration and ohmic）. Effect of incomplete conversions is modeled by assuming that substrates can be remained after the reaction and that side reactions may occur. Optimum and feasibility conditions are discussed for basic input parameters of the cell. Calculations of maximum power show that the data differ for power generated and consumed and depend on current intensity, number of mass transfer units, polarizations, electrode surface area, average chemical rate, etc.. These data provide bounds for SOFC energy generators, which are more exact and informative than reversible bounds for electrochemical transformation.展开更多
In this study,the controlled nucleation and growth of gold nanoparticles(GNPs)were investigated using a self-repelled mist in a liquid chemical reaction environment.An electrospray-based chemical reduction method was ...In this study,the controlled nucleation and growth of gold nanoparticles(GNPs)were investigated using a self-repelled mist in a liquid chemical reaction environment.An electrospray-based chemical reduction method was conducted in the aqueous region and at room temperature to synthesize the polymeric-stabilized gold nanoparticles.The electrospray technique was used to atomize a hydrogen tetrachloraurate(III)(HAuCl4)precursor solution into electrostatically charged droplets.The atomized droplets were dispersed in an aqueous reaction bath containing L-ascorbic acid as a reducing agent and polyvinylpyrrolidone(PVP)as a stabilizer.The effect of the electrospray parameters,specifically the flow rate and electrospray droplet size,as well as the reaction conditions such as the concentration of reactants,pH,and stabilizer(PVP),were investigated.The mean diameter of the GNPs increased from around 4 to 9 nm with an increase in the electrospray flow rate,droplet size,and current passing through the electrospray jet.Spherical and monodispersed GNPs were synthesized at a relatively high flow rate of 2 mL/h and a moderate concentration of 2 mM of precursor solution.The smallest-sized GNP with a high monodispersity was obtained in the reaction bath at a high pH of 10.5 and in the presence of PVP.It is expected that continuous and mass production of the engineered GNPs and other noble metal nanoparticles could be established for scaling up nanoparticle production via the proposed electrospray-based chemical reduction method.展开更多
The rapid industrial and economic development runs on fossil fuel and other energy sources.Limited oil reserves,environmental issues,and high transportation costs lead towards carbon unbiased renewable and sustainable...The rapid industrial and economic development runs on fossil fuel and other energy sources.Limited oil reserves,environmental issues,and high transportation costs lead towards carbon unbiased renewable and sustainable fuel.Compared to other carbon-based fuels,biodiesel is attracted worldwide as a biofuel for the reduction of global dependence on fossil fuels and the greenhouse effect.During biodiesel production,approximately 10%of glycerol is formed in the transesterification process in a biodiesel plant.The ditching of crude glycerol is important as it contains salt,free fatty acids,and methanol that cause contamination of soil and creates environmental challenges for researchers.However,the excessive cost of crude glycerol refining and market capacity encourage the biodiesel industries for developing a new idea for utilising and produced extra sources of income and treat biodiesel waste.This review focuses on the significance of crude glycerol in the value-added utilisation and conversion to bioethanol by a fermentation process and describes the opportunities of glycerol in various applications.展开更多
Seepage or loss of the mix-water from the drilling muds into the porous and permeable formations is a common problem during drilling operation.The drilling mud design requires a good knowledge of sealing integrity and...Seepage or loss of the mix-water from the drilling muds into the porous and permeable formations is a common problem during drilling operation.The drilling mud design requires a good knowledge of sealing integrity and all the factors influencing the mud to bridge through fractures or pore throat of exposed rocks.Loss circulation materials(LCMs)are commonly introduced into the drilling mud to prevent or minimize filtrate loss.This study investigates silica nanoparticle(SNP)derived from rice husk(RH)termed RH-SNP using the wet-milling method as an LCM inwater-based mud(WBM).The impact of the RH-SNP in the enhancement of rheology and filtrate loss control properties of WBM was studied.Subsequently,the sealing integrity of the RH-SNP in a 1 mm and 2 mm simulated fracture for 7 min was determined using a stainless-steel slotted filter disk.The performance of the developed RH-SNP was compared with the widely applied nutshell.The synthesized RH-SNP at amount of 2.0 wt% significantly enhanced the yield point and plastic viscosity of the WBM by 75% and 386%,respectively,and minimized the fluid loss of the WBM by 47% at 80°F.The enhancement is due to the particles ability to spread and interact efficiently with the WBM.With the use of 1 mm and 2 mm simulated fracture for 7 min,the mud loss volume of the base mud reduced by 50%,66.7%,86%,and 90%(for 1 mm)and 40%,65.7%,77.1%,and 80%(for 2 mm)with the inclusion of 0.5 wt%,1.0 wt%,1.5 wt%,and 2.0 wt% of RH-SNP,respectively.Overall,the results showed that RH-SNP enhanced the seal integrity of the drilling mud and was more resistant to deformation compared to the nutshell.The findings of this study can help for better understanding of the application of RH-SNP as a loss circulation agent owing to its superior ability to seal fractured formation compared with the often used nutshell.展开更多
In this paper, the flow patterns observed in horizontal Couette-Taylor flow（CTF） were correlated using dimensionless numbers. The analysis of the results showed that the structure of the flow was an outcome of inter...In this paper, the flow patterns observed in horizontal Couette-Taylor flow（CTF） were correlated using dimensionless numbers. The analysis of the results showed that the structure of the flow was an outcome of interaction between fluid inertia related to axial and rotational flows and gravitation. Therefore, the flow structures were correlated using axial and angular Reynolds numbers, and Archimedes number for the given value of gas-to-liquid flow ratio. Finally, the correlation for the prediction of the transition to the flow regime observed at high rotational speeds was proposed. The comparison with experiments carried out in the vertical CTF from the literature showed that this correlation can also be useful in the case of vertical flow.展开更多
Wax molecules tend to aggregate,and form wax solid at low temperature and result in a wax deposition.Chemical wax inhibitors are introduced to prevent wax deposition.However,the performance of chemical wax inhibitors ...Wax molecules tend to aggregate,and form wax solid at low temperature and result in a wax deposition.Chemical wax inhibitors are introduced to prevent wax deposition.However,the performance of chemical wax inhibitors is temperature dependent.Computational method using Molecular Dynamics(MD)simulation is used in this research to investigate how temperature affects wax inhibition using 2,5,8,11 Tetramethyl 6 dodecyn-5,8 Diol Ethoxylate Gemini surfactant(GS)and nanoparticles silicon dioxide(NP1),tin oxide(NP2),and nickel oxide(NP3).Wax-wax interaction of H58⋯H61of n-icosane and wax-solute interaction of hydrogen atom from n-icosane wax and carbonyl oxygen atoms from GS and NPs was investigated via radial distribution function analysis(rdf).The findings revealed that GS/NPs blends have a better chance of wax inhibition than corresponding individuals.Besides that,wax-wax interaction was strongest at 288K,indicating the higher chances of wax formation at low temperature.MD simulation is a promising tool for identifying atoms responsible for the wax formation and inhibition and can be used for chemical wax inhibitor screening for different temperature.展开更多
Cellulose nanocrystal(CNC)with distinctive shape-morphology,enhanced thermal stability and dispersibility is essential for overcoming the challenges in processing polymer/CNC nanocom-posites through melt compounding a...Cellulose nanocrystal(CNC)with distinctive shape-morphology,enhanced thermal stability and dispersibility is essential for overcoming the challenges in processing polymer/CNC nanocom-posites through melt compounding at elevated temperatures.This study shows a mixed acid hy-drolysis method to produce CNC with improved thermal stability and high productivity.The use of phosphoric acid(H_(3)PO_(4)),as a mild acid,in combination with a strong acid either sulphuric acid(H_(2)SO_(4))or hydrochloric acid(HCl)leads to reduced use of strong acids and low impact on our environment.The influences of acid combination and sequence of addition on the production yield were investigated by retaining the proportion of H_(3)PO_(4)to corrosive acid(H_(2)SO_(4)and HCl)4 to 1,and solid to liquid ratio 1꞉75.This methodology has enabled to isolate CNC with higher thermal stability,dispersibility and productivity in terms of amount acid used 1 g of CNC,as compared with single acid hydrolysis.The CNC produced using the combination of H_(3)PO_(4)and HCl exhibits high thermal stability,dispersibility and rod-like shape morphology with length and width of(424±86)and(22±3)nm,respectively.Moreover,this approach has reduced H_(3)PO_(4)consumption by 54%as compared with single acid hydrolysis method for the production of same amount of CNC.展开更多
文摘The accurate prediction of the droplet size distribution(DSD)in liquid–liquid turbulent dispersions is of fundamental importance in many industrial applications and it requires suitable kernels in the population balance model.When a surfactant is included in liquid–liquid dispersions,the droplet breakup behavior will change as an effect of the reduction of the interfacial tension.Moreover,also the dynamic interfacial tension may be different with respect to the static,due to the fact that the surfactant may be easily desorbed from the droplet surface,generating additional disruptive stresses.In this work,the performance of five breakup kernels from the literature is assessed,to investigate their ability to predict the time evolution of the DSD and of the mean Sauter diameter,when different surfactants are employed.Simulations are performed with the Quadrature Method of Moments for the solution of the population balance model coupled with the two-fluid model implemented in the compressible Two Phase Euler Foam solver of the open-source computational fluid dynamics(CFD)code Open FOAM v.2.2.x.The time evolution of the mean Sauter diameter predicted by these kernels is validated against experimental data for six test cases referring to a stirred tank with different types of surfactants(Tween 20 and PVA 88%)at different concentrations operating under different stirrer rates.Our results show that for the dispersion containing Tween 20 additional stress is generated,the multifractal breakup kernel properly predicts the DSD evolution,whereas two other kernels predict too fast breakup of droplets covered by adsorbed PVA.Kernels derived originally for bubbles completely fail.
文摘Steady-state model of a high-temperature solid oxide fuel cell （SOFC） is considered, which refers to constant chemical potentials of incoming hydrogen fuel and oxidant. Lowering of the cell voltage below its reversible value is attributed to polarizations and imperfect conversions of reactions. An imperfect power formula summarizes the effect of transport laws, irreversible polarizations and efficiency of power yield. Reversible electrochemical theory is extended to the case with dissipative chemical reactions; this case includes systems with incomplete conversions, characterized by ＂reduced affinities＂ and an idle run voltage. Efficiency drop is linked with thermodynamic and electrochemical irreversibilities expressed in terms of polarizations （activation, concentration and ohmic）. Effect of incomplete conversions is modeled by assuming that substrates can be remained after the reaction and that side reactions may occur. Optimum and feasibility conditions are discussed for basic input parameters of the cell. Calculations of maximum power show that the data differ for power generated and consumed and depend on current intensity, number of mass transfer units, polarizations, electrode surface area, average chemical rate, etc.. These data provide bounds for SOFC energy generators, which are more exact and informative than reversible bounds for electrochemical transformation.
基金This paper was supported by the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20191019)the Natural Science Research Project in Colleges and Universities in Jiangsu Province of China(Grant No.19KJB470022)+1 种基金the Scientific Research Start-up Foundation funding of High-level Introduction Talents of Nanjing Institute of Technology(Grant No.YKJ201912)the Open Fund Project of the Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education of Southeast University.
文摘In this study,the controlled nucleation and growth of gold nanoparticles(GNPs)were investigated using a self-repelled mist in a liquid chemical reaction environment.An electrospray-based chemical reduction method was conducted in the aqueous region and at room temperature to synthesize the polymeric-stabilized gold nanoparticles.The electrospray technique was used to atomize a hydrogen tetrachloraurate(III)(HAuCl4)precursor solution into electrostatically charged droplets.The atomized droplets were dispersed in an aqueous reaction bath containing L-ascorbic acid as a reducing agent and polyvinylpyrrolidone(PVP)as a stabilizer.The effect of the electrospray parameters,specifically the flow rate and electrospray droplet size,as well as the reaction conditions such as the concentration of reactants,pH,and stabilizer(PVP),were investigated.The mean diameter of the GNPs increased from around 4 to 9 nm with an increase in the electrospray flow rate,droplet size,and current passing through the electrospray jet.Spherical and monodispersed GNPs were synthesized at a relatively high flow rate of 2 mL/h and a moderate concentration of 2 mM of precursor solution.The smallest-sized GNP with a high monodispersity was obtained in the reaction bath at a high pH of 10.5 and in the presence of PVP.It is expected that continuous and mass production of the engineered GNPs and other noble metal nanoparticles could be established for scaling up nanoparticle production via the proposed electrospray-based chemical reduction method.
基金Universiti Malaysia Pahang for providing financial support through higher education Malaysia’s ministry under the fundamental research grant scheme number FRGS/1/2019/STG05/UMP/01/1(UMP internal Reference no RDU1901123).
文摘The rapid industrial and economic development runs on fossil fuel and other energy sources.Limited oil reserves,environmental issues,and high transportation costs lead towards carbon unbiased renewable and sustainable fuel.Compared to other carbon-based fuels,biodiesel is attracted worldwide as a biofuel for the reduction of global dependence on fossil fuels and the greenhouse effect.During biodiesel production,approximately 10%of glycerol is formed in the transesterification process in a biodiesel plant.The ditching of crude glycerol is important as it contains salt,free fatty acids,and methanol that cause contamination of soil and creates environmental challenges for researchers.However,the excessive cost of crude glycerol refining and market capacity encourage the biodiesel industries for developing a new idea for utilising and produced extra sources of income and treat biodiesel waste.This review focuses on the significance of crude glycerol in the value-added utilisation and conversion to bioethanol by a fermentation process and describes the opportunities of glycerol in various applications.
基金Ministry of Higher Education,Malaysia and UTM for the grants used to support this research(Q.J130000.3551.07G12,R.J130000.7851.5F030,Q.J1300003551.06G68,R.J1300007351.4B545)。
文摘Seepage or loss of the mix-water from the drilling muds into the porous and permeable formations is a common problem during drilling operation.The drilling mud design requires a good knowledge of sealing integrity and all the factors influencing the mud to bridge through fractures or pore throat of exposed rocks.Loss circulation materials(LCMs)are commonly introduced into the drilling mud to prevent or minimize filtrate loss.This study investigates silica nanoparticle(SNP)derived from rice husk(RH)termed RH-SNP using the wet-milling method as an LCM inwater-based mud(WBM).The impact of the RH-SNP in the enhancement of rheology and filtrate loss control properties of WBM was studied.Subsequently,the sealing integrity of the RH-SNP in a 1 mm and 2 mm simulated fracture for 7 min was determined using a stainless-steel slotted filter disk.The performance of the developed RH-SNP was compared with the widely applied nutshell.The synthesized RH-SNP at amount of 2.0 wt% significantly enhanced the yield point and plastic viscosity of the WBM by 75% and 386%,respectively,and minimized the fluid loss of the WBM by 47% at 80°F.The enhancement is due to the particles ability to spread and interact efficiently with the WBM.With the use of 1 mm and 2 mm simulated fracture for 7 min,the mud loss volume of the base mud reduced by 50%,66.7%,86%,and 90%(for 1 mm)and 40%,65.7%,77.1%,and 80%(for 2 mm)with the inclusion of 0.5 wt%,1.0 wt%,1.5 wt%,and 2.0 wt% of RH-SNP,respectively.Overall,the results showed that RH-SNP enhanced the seal integrity of the drilling mud and was more resistant to deformation compared to the nutshell.The findings of this study can help for better understanding of the application of RH-SNP as a loss circulation agent owing to its superior ability to seal fractured formation compared with the often used nutshell.
文摘In this paper, the flow patterns observed in horizontal Couette-Taylor flow（CTF） were correlated using dimensionless numbers. The analysis of the results showed that the structure of the flow was an outcome of interaction between fluid inertia related to axial and rotational flows and gravitation. Therefore, the flow structures were correlated using axial and angular Reynolds numbers, and Archimedes number for the given value of gas-to-liquid flow ratio. Finally, the correlation for the prediction of the transition to the flow regime observed at high rotational speeds was proposed. The comparison with experiments carried out in the vertical CTF from the literature showed that this correlation can also be useful in the case of vertical flow.
基金The authors gratefully acknowledge the financial support provided by Universiti Malaysia Pahang under Internal Research grant RDU200302.
文摘Wax molecules tend to aggregate,and form wax solid at low temperature and result in a wax deposition.Chemical wax inhibitors are introduced to prevent wax deposition.However,the performance of chemical wax inhibitors is temperature dependent.Computational method using Molecular Dynamics(MD)simulation is used in this research to investigate how temperature affects wax inhibition using 2,5,8,11 Tetramethyl 6 dodecyn-5,8 Diol Ethoxylate Gemini surfactant(GS)and nanoparticles silicon dioxide(NP1),tin oxide(NP2),and nickel oxide(NP3).Wax-wax interaction of H58⋯H61of n-icosane and wax-solute interaction of hydrogen atom from n-icosane wax and carbonyl oxygen atoms from GS and NPs was investigated via radial distribution function analysis(rdf).The findings revealed that GS/NPs blends have a better chance of wax inhibition than corresponding individuals.Besides that,wax-wax interaction was strongest at 288K,indicating the higher chances of wax formation at low temperature.MD simulation is a promising tool for identifying atoms responsible for the wax formation and inhibition and can be used for chemical wax inhibitor screening for different temperature.
文摘Cellulose nanocrystal(CNC)with distinctive shape-morphology,enhanced thermal stability and dispersibility is essential for overcoming the challenges in processing polymer/CNC nanocom-posites through melt compounding at elevated temperatures.This study shows a mixed acid hy-drolysis method to produce CNC with improved thermal stability and high productivity.The use of phosphoric acid(H_(3)PO_(4)),as a mild acid,in combination with a strong acid either sulphuric acid(H_(2)SO_(4))or hydrochloric acid(HCl)leads to reduced use of strong acids and low impact on our environment.The influences of acid combination and sequence of addition on the production yield were investigated by retaining the proportion of H_(3)PO_(4)to corrosive acid(H_(2)SO_(4)and HCl)4 to 1,and solid to liquid ratio 1꞉75.This methodology has enabled to isolate CNC with higher thermal stability,dispersibility and productivity in terms of amount acid used 1 g of CNC,as compared with single acid hydrolysis.The CNC produced using the combination of H_(3)PO_(4)and HCl exhibits high thermal stability,dispersibility and rod-like shape morphology with length and width of(424±86)and(22±3)nm,respectively.Moreover,this approach has reduced H_(3)PO_(4)consumption by 54%as compared with single acid hydrolysis method for the production of same amount of CNC.
