In the steam thermal cracking of naphtha,the hydrocarbon stream flows inside tubular reactors and is exposed to flames of a series of burners in the firebox.In this paper,a full three-dimensional computational fluid d...In the steam thermal cracking of naphtha,the hydrocarbon stream flows inside tubular reactors and is exposed to flames of a series of burners in the firebox.In this paper,a full three-dimensional computational fluid dynamics(CFD)model was developed to investigate the process variables in the firebox and reactor coil of an industrial naphtha furnace.This comprehensive CFD model consists of a standard k-εturbulence model accompanied by a molecular kinetic reaction for cracking,detailed combustion model,and radiative properties.In order to improve the steam cracking performance,the model is solved using a proposed iterative algorithm.With respect to temperature,product yield and specially propylene-toethylene ratio(P/E),the simulation results agreed well with industrial data obtained from a mega olefin plant of a petrochemical complex.The deviation of P/E results from industrial data was less than 2%.The obtained velocity,temperature,and concentration profiles were used to investigate the residence time,coking rate,coke concentration,and some other findings.The coke concentration at coil exit was1.9×10^(-3)%(mass)and the residence time is calculated to be 0.29 s.The results can be used as a scientific guide for process engineers.展开更多
As telecommunication and RF power electronics applications continue to push the envelope of waste heat dissipation, more and more, we see a need for active thermal control employing forced air electronic cooling fans ...As telecommunication and RF power electronics applications continue to push the envelope of waste heat dissipation, more and more, we see a need for active thermal control employing forced air electronic cooling fans in unison with pumped fluid loops in order to meet temperature and performance requirements. This research paper presents results of applying Computational Fluid Dynamics (CFD) commercial industry STAR-CCM+ software for heat transfer and fluid flow simulation of a novel heat exchanger/cold plate fabricated from k-core high thermal conductivity material in order to realize thermal control system hardware design for very much applications to very large power density (~1 kW/m2) electronics packaging scenarios. Trade studies involving different heat exchanger/cold plate materials, as well as vari- ous fault scenarios within a mock-up of a typical electronics system, are used to illustrate the upper bounds placed on the convective heat transfer coefficient. Agreement between our present findings and previous research in the field of electronics cooling is presented herein.展开更多
This paper reports a study on the role of fluid flow pattern and dynamic pressure on the permeate flux through a micro filtration membrane in laboratory scale.For this purpose,a dead-end membrane cell equipped with a ...This paper reports a study on the role of fluid flow pattern and dynamic pressure on the permeate flux through a micro filtration membrane in laboratory scale.For this purpose,a dead-end membrane cell equipped with a marine type impeller was used.The impeller was set to rotate in the clockwise and counter clockwise directions with the same angular velocities in order to illustrate the effect of rotation direction on permeate flux.Consequently, permeate fluxes were measured at various impeller rotational speeds.The computational fluid dynamics（CFD）predicted dynamic pressure was related to the fluxes obtained in the experiments.Using the CFD modeling,it is proven that the change in dynamic pressure upon the membrane surface has direct effect on the permeate flux.展开更多
基金the support of Bandar-eImam petrochemical company(BIPC),Iran。
文摘In the steam thermal cracking of naphtha,the hydrocarbon stream flows inside tubular reactors and is exposed to flames of a series of burners in the firebox.In this paper,a full three-dimensional computational fluid dynamics(CFD)model was developed to investigate the process variables in the firebox and reactor coil of an industrial naphtha furnace.This comprehensive CFD model consists of a standard k-εturbulence model accompanied by a molecular kinetic reaction for cracking,detailed combustion model,and radiative properties.In order to improve the steam cracking performance,the model is solved using a proposed iterative algorithm.With respect to temperature,product yield and specially propylene-toethylene ratio(P/E),the simulation results agreed well with industrial data obtained from a mega olefin plant of a petrochemical complex.The deviation of P/E results from industrial data was less than 2%.The obtained velocity,temperature,and concentration profiles were used to investigate the residence time,coking rate,coke concentration,and some other findings.The coke concentration at coil exit was1.9×10^(-3)%(mass)and the residence time is calculated to be 0.29 s.The results can be used as a scientific guide for process engineers.
文摘As telecommunication and RF power electronics applications continue to push the envelope of waste heat dissipation, more and more, we see a need for active thermal control employing forced air electronic cooling fans in unison with pumped fluid loops in order to meet temperature and performance requirements. This research paper presents results of applying Computational Fluid Dynamics (CFD) commercial industry STAR-CCM+ software for heat transfer and fluid flow simulation of a novel heat exchanger/cold plate fabricated from k-core high thermal conductivity material in order to realize thermal control system hardware design for very much applications to very large power density (~1 kW/m2) electronics packaging scenarios. Trade studies involving different heat exchanger/cold plate materials, as well as vari- ous fault scenarios within a mock-up of a typical electronics system, are used to illustrate the upper bounds placed on the convective heat transfer coefficient. Agreement between our present findings and previous research in the field of electronics cooling is presented herein.
文摘This paper reports a study on the role of fluid flow pattern and dynamic pressure on the permeate flux through a micro filtration membrane in laboratory scale.For this purpose,a dead-end membrane cell equipped with a marine type impeller was used.The impeller was set to rotate in the clockwise and counter clockwise directions with the same angular velocities in order to illustrate the effect of rotation direction on permeate flux.Consequently, permeate fluxes were measured at various impeller rotational speeds.The computational fluid dynamics（CFD）predicted dynamic pressure was related to the fluxes obtained in the experiments.Using the CFD modeling,it is proven that the change in dynamic pressure upon the membrane surface has direct effect on the permeate flux.
