The present article deals with thermally stratified stagnation-point flow saturated in porous medium on surface of variable thickness along with more convincing and reliable surface condition termed as melting heat tr...The present article deals with thermally stratified stagnation-point flow saturated in porous medium on surface of variable thickness along with more convincing and reliable surface condition termed as melting heat transfer.Homogeneous–heterogeneous reaction and radiative effects have been further taken into account to reconnoiterproperties of heat transfer.Melting heat transfer and phenomenon of homogeneous–heterogeneous reaction have engrossed widespread utilization in purification of metals,welding process,electroslag melting,biochemical systems,catalysis and several industrial developments.Suitable transformations are utilized to attain a scheme of ordinary differential equations possessing exceedingly nonlinear nature.Homotopic process is employed to develop convergent solutions of the resulting problem.Discussion regarding velocity,thermal field and concentration distribution for several involved parameters is pivotal part.Graphical behaviors of skin friction coefficient and Nusselt number are also portrayed.Concentration of the reactants is found to depreciate as a result of strength of both heterogeneous and homogeneous reaction parameters.With existence of melting phenomenon,declining attitude of fluid temperature is observed for higher radiation parameter.展开更多
Chemical warfare agents(CWA)are stockpiled in large quantities across the globe.Agents stored in inaccessible facilities need to be destroyed rapidly without dispersing the compounds to surrounding areas.Metal-based e...Chemical warfare agents(CWA)are stockpiled in large quantities across the globe.Agents stored in inaccessible facilities need to be destroyed rapidly without dispersing the compounds to surrounding areas.Metal-based energetic formulations are used in such prompt defeat applications to rapidly decompose the CWA by generating a high temperature environment.An alternate,and possibly a more effective decomposition pathway could be provided by chemicidal action of aerosolized condensed combustion products,which typically consist of metal oxides.Toxic fumes that escape the high temperature blast zone can be neutralized by smoke generated during combustion,depending on the particle size,surface characteristics,chemical properties,and concentration of this smoke.This review considers relevant experimental and modeling studies quantifying decomposition of CWA comprising organophosphorus compounds and their surrogates on the surface of various metal oxides.Dimethyl methylphosphonate(DMMP),a sarine surrogate,was used most commonly for such experiments.Many reported efforts focused on the mechanisms of adsorption of DMMP to various metal oxides and initial reaction steps cleaving various bonds from the chemisorbed molecules.For selected oxides,these experiments were supported by quantum-mechanical calculations.In other studies,the capacity of oxide surfaces to adsorb and decompose DMMP was quantified.In most cases,porous catalysts were used although limited experimental data are available for aerosolized nonporous oxide particles.The reported experimental data applicable to scenarios involving prompt decomposition of CWA are summarized.It is noted that information is lacking describing respective heterogeneous reaction kinetics.Preliminary estimates of aerosolized smoke particle concentrations required to destroy CWA are made considering gas phase diffusion rates and reported values of the oxide capacity to decompose CWA or their surrogates.展开更多
文摘The present article deals with thermally stratified stagnation-point flow saturated in porous medium on surface of variable thickness along with more convincing and reliable surface condition termed as melting heat transfer.Homogeneous–heterogeneous reaction and radiative effects have been further taken into account to reconnoiterproperties of heat transfer.Melting heat transfer and phenomenon of homogeneous–heterogeneous reaction have engrossed widespread utilization in purification of metals,welding process,electroslag melting,biochemical systems,catalysis and several industrial developments.Suitable transformations are utilized to attain a scheme of ordinary differential equations possessing exceedingly nonlinear nature.Homotopic process is employed to develop convergent solutions of the resulting problem.Discussion regarding velocity,thermal field and concentration distribution for several involved parameters is pivotal part.Graphical behaviors of skin friction coefficient and Nusselt number are also portrayed.Concentration of the reactants is found to depreciate as a result of strength of both heterogeneous and homogeneous reaction parameters.With existence of melting phenomenon,declining attitude of fluid temperature is observed for higher radiation parameter.
基金This work was supported by the US Defense Threat Reduction Agency,DTRAGrant HDTRA1-19-1-0023.
文摘Chemical warfare agents(CWA)are stockpiled in large quantities across the globe.Agents stored in inaccessible facilities need to be destroyed rapidly without dispersing the compounds to surrounding areas.Metal-based energetic formulations are used in such prompt defeat applications to rapidly decompose the CWA by generating a high temperature environment.An alternate,and possibly a more effective decomposition pathway could be provided by chemicidal action of aerosolized condensed combustion products,which typically consist of metal oxides.Toxic fumes that escape the high temperature blast zone can be neutralized by smoke generated during combustion,depending on the particle size,surface characteristics,chemical properties,and concentration of this smoke.This review considers relevant experimental and modeling studies quantifying decomposition of CWA comprising organophosphorus compounds and their surrogates on the surface of various metal oxides.Dimethyl methylphosphonate(DMMP),a sarine surrogate,was used most commonly for such experiments.Many reported efforts focused on the mechanisms of adsorption of DMMP to various metal oxides and initial reaction steps cleaving various bonds from the chemisorbed molecules.For selected oxides,these experiments were supported by quantum-mechanical calculations.In other studies,the capacity of oxide surfaces to adsorb and decompose DMMP was quantified.In most cases,porous catalysts were used although limited experimental data are available for aerosolized nonporous oxide particles.The reported experimental data applicable to scenarios involving prompt decomposition of CWA are summarized.It is noted that information is lacking describing respective heterogeneous reaction kinetics.Preliminary estimates of aerosolized smoke particle concentrations required to destroy CWA are made considering gas phase diffusion rates and reported values of the oxide capacity to decompose CWA or their surrogates.
