Theory of convective droplet vaporization with unsteady heat transfer in the circulating liquid phase

Prakash, Shiva; Sirignano, William A.

doi:10.1016/0017-9310(80)90113-1

Cited by 158 publications

(28 citation statements)

References 2 publications

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“…pressure. The estimation of the system state can be made by applying the Antoine equation ( Ref 14,18,19), which is given by:…”

Section: Droplet Formation Evaporation and Combustion Of Ethanol Somentioning

confidence: 99%

“…Particle breakup is modeled using the Blob method (Ref 16,18) for disperse droplets and the ETAP method (Ref 18) for disperse solids, taking into account the Weber (Eq 7) and Reynolds number (Eq 5) of each particle. In the Blob method, it is assumed that a detailed description of the atomization and breakup processes within the primary breakup zone of the spray is not required.…”

Section: Process Modeling and Boundary Conditionsmentioning

confidence: 99%

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Modeling of Combustion as well as Heat, Mass, and Momentum Transfer During Thermal Spraying by HVOF and HVSFS

et al. 2009

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In thermal spray technologies and coating industries, increasing research and development efforts have been made in recent years toward submicron and nanostructured layers on different materials and components, promising large potentials in functional and structural coating properties. These potentials have been encouraging researchers to aim for an improved understanding and optimization of the highvelocity oxide fuel (HVOF) system to be able to improve process control, and thus, control coating properties and enable better applications for submicron and nanostructured coatings. Moreover, on the experimental side, new thermal spray technologies have been developed in order to process nanopowders, i.e., mainly suspension-based technologies like suspension plasma spraying or high-velocity suspension flame spraying (HVSFS). HVSFS is a suitable processing method for submicron and nanoscaled particles to achieve dense surface layers in supersonic mode with a refined final structure, which is the prerequisite for improved or even superior mechanical and physical properties. However, theoretical understanding of the chemical and thermodynamic phenomena occurring in the HVOF and HVSFS reacting flow field, which is necessary for process modeling, is a challenging, multidisciplinary issue. In this study, the combustion processes as well as the heat-, mass-, and momentum interactions between the flame, the suspension droplets (including vaporization), and the solid spray particles are analyzed, taking into account both the HVOF and HVSFS spray processes. The processes are modeled and numerical simulation experiments are described. Thereby, the models are giving a detailed description of the relevant set of parameters describing the complete spraying process in the combustion chamber and expansion nozzle, respectively. Simulation results can be applied for improved process control as well as torch design, e.g., adaptation of combustion chamber design to the trajectories and dwell time of spray particles for heat transfer optimization.

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“…pressure. The estimation of the system state can be made by applying the Antoine equation ( Ref 14,18,19), which is given by:…”

Section: Droplet Formation Evaporation and Combustion Of Ethanol Somentioning

confidence: 99%

Section: Process Modeling and Boundary Conditionsmentioning

confidence: 99%

Modeling of Combustion as well as Heat, Mass, and Momentum Transfer During Thermal Spraying by HVOF and HVSFS

et al. 2009

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“…Nevertheless, almost all the studies in the convective case have neglected droplet deformation, that is, considered effectively the limit of small Weber numbers (i.e., strong surface tension). Under this restriction, analytical studies [9,10] have been based on a boundary-layer analysis at the front surface of the droplet, which typically leads to gasification/combustion times inversely proportional to the square root of a suitably defined diffusion coefficient. Account for nonsmall, but finite values, of the Weber number has been taken in the numerical study by Deng et al [13] and has been found to result in an increase in the overall vaporization rate due to deformation.…”

Section: Introductionmentioning

confidence: 99%

Ignition and combustion of fuel pockets moving in an oxidizing atmosphere

Daou¹

1998

Combustion and Flame

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“…It is known that, in the case of convective heat supply to such a drop, heat is transferred from the surface of the drop into its inside due to the heat conduction of the material of the drop and, probably, due to the convection. In this case, the infl uence of the circulation of the liquid inside the drop on the heat and mass transfer in it, which is signifi cant for multicomponent liquids, is a problem that remains to be solved [4]. In [5], the boundaries of applicability of the Maxwell theory to small drops were discussed, because the rate of evaporation of these drops is limited by not the diffusion but the rate of emission of molecules from their surface.…”

mentioning

confidence: 98%

“…The heat supplied to the drop due to the convective heat fl ow, the infrared radiation, and the microwave radiation is calculated as 4 …”

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confidence: 99%

Heat and Mass Exchange of a Drop of a Solution Subjected to a Combined Energy Action Under Conditions of Deepening of the Evaporation Zone

Akulich

2016

J Eng Phys Thermophy

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A model of the heat and mass exchange in the evaporation of drops moving in the carrying gas phase of a solution subjected to the combined energy action of a convective heat fl ow and electromagnetic infrared and microwave radiations under conditions where the size of the drops changes at the low-temperature stage of their evaporation and the evaporation zone deepens at the high-temperature stage of the evaporation process has been formulated. Kinetic dependences and features of the movement of the evaporation boundary in the process of dehydration of the indicated drops have been determined. Keywords: heat and moisture transfer, kinetics and dynamics of mass transfer, mass exchange of a drop of a solution.Introduction. The heat and mass transfer taking place in disperse systems gas-liquid particles, used in different industries, determines the effi ciency of many production processes, including the dispersion dehydration of solutions [1-3]. However, the interrelation of the structural, mechanical, physicochemical, heat transfer, and mass transfer effects in the indicated processes is not completely understood.The high-temperature dehydration of dispersed solutions can be simulated on the basis of the equations of transfer in each phase of a solution with regard for its thermophysical characteristics and the coeffi cient of heat and mass transfer in it. However, since the heat and mass exchange in a dispersed solution infl uences the formation of the structure of dry particles in it, the dehydration of drops of this solution is fairly diffi cult to simulate from the physical and mathematical standpoints. A characteristic feature of the drying of drops of a solution or a suspension is the formation, at a defi nite stage of the process, of a solid-phase structure or a crust on their surface [2]. Moisture is transferred though this crust to the surface of a drop, with the result that its porous structure is deformed. The low-temperature stage of dehydration of a drop is completed when the moisture content in it decreases and the dry structure of its solid phase is formed. The structure of a dehydrated particle and its shape and size are determined by the physical properties of the material of the particle, the conditions of its dispersion, and the heat and mass transfer in it. The processes of heat and mass exchange of drops of solutions subjected to the spray drying under the action of a convective heat fl ow are well understood. As already noted, the formation of a crust on the surface of a drop of a solution has been detected and, in [2], this physical phenomenon was described mathematically.The heat and mass transfer in drops of solutions and suspensions and the structure formation in them under the combined energy action of a convective heat fl ow, an infrared (IR) radiation, and a microwave (MW) radiation are less understood. It is known that, in the case of convective heat supply to such a drop, heat is transferred from the surface of the drop into its inside due to the heat conduction of the material of the ...

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Theory of convective droplet vaporization with unsteady heat transfer in the circulating liquid phase

Cited by 158 publications

References 2 publications

Modeling of Combustion as well as Heat, Mass, and Momentum Transfer During Thermal Spraying by HVOF and HVSFS

Modeling of Combustion as well as Heat, Mass, and Momentum Transfer During Thermal Spraying by HVOF and HVSFS

Ignition and combustion of fuel pockets moving in an oxidizing atmosphere

Heat and Mass Exchange of a Drop of a Solution Subjected to a Combined Energy Action Under Conditions of Deepening of the Evaporation Zone

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