Knowledge of the temperature profile of the gases produced by the combustion of fossil fuels with... more Knowledge of the temperature profile of the gases produced by the combustion of fossil fuels with air is a desirable step in the thermal protection systems. These gases are generally associated with high temperatures and steep temperature gradients. The measurement of temperature profiles of combustion products are often hard to make using thermocouples and other immersed pyrometers because such probes may have to be immersed in inaccessible and possibly destructive media. Determination of gas temperature profiles from multi-frequency radiative measurements seems an attractive alternative. This could be accomplished by radiative heat transfer probing and the application of the principle of inversion, where inversion is the process of inferring the internal parameters of a system of outside measurements, without the interruption of the combustion system itself.This paper discusses the development of models to retrieve the temperature distribution in a flame system by remote spectral sensing. Mixed Gray-Gas models were developed to calculate water vapor and carbon dioxide standard emissivities. The evaluation of combustion system spectral radiant flux was simulated and a model was developed and successfully tested for the application of temperature inversion.
The main sources of non-luminous gas radiation in furnaces are carbon dioxide and water vapor. Ap... more The main sources of non-luminous gas radiation in furnaces are carbon dioxide and water vapor. Approximation of the standard emissivities of water vapor and of carbon dioxide by mixed gray-gas model is studied. The model developed for carbon dioxide standard emi s si vi ti es covers a range of temperature of 3DO-1BOOK and a partial-pressure-length product range of 0.01 to 10 m atm. A mixture of six gray gases was adequate to cover the whole range. For the water vapor thermal radiation two models were developed to approximate the standard water ~apor emissi~ities. In the first model water ~apor is approximated by a mixture of four gray-gases and can be used in the temperature range of 300-700K and the partial-pressure-length range of 0.01 to 2 m atm. The second model is a piece-wise one in which one gray gas is used to cover the pL range 0.5-2 m and a second gray gas covered the range of 0.05-0.5 m. The model may be used in the temperature range of 700-l500K and has an error range of -2.3 to 3.7~.
... and TAREK A. ALLAM Deparrmenr of Chemical Engineering University of New Hampshire Durham, New... more ... and TAREK A. ALLAM Deparrmenr of Chemical Engineering University of New Hampshire Durham, New Hampshire 03824-3591 ... The knowledge of the emissivities of carbon dioxide and water vapor is very important in burner design and thermal efficiency calculations. ...
Bioprocess and Biosystems Engineering, Nov 22, 2000
In the present study the oxygen mass transfer from the gas to the aqueous phase in a Three-Phase ... more In the present study the oxygen mass transfer from the gas to the aqueous phase in a Three-Phase Inverse Fluidized Bed (TPIFB) has been studied. A pilot scale TPIFB has been designed and constructed. For determination of the volumetric oxygen mass transfer coefficient the elegant dynamic method, described by Dang et al. (1977) was used. The influence of hydrodynamic parameters,
This publication contains 12 papers of which 2 appear as abstracts only. The volume is based upon... more This publication contains 12 papers of which 2 appear as abstracts only. The volume is based upon papers presented at the 89th National AIChE Meeting, August 17-20, 1980, in Portland, Oregon and the 73rd AIChE Annual Meeting, held November 16-20 1980, in Chicago, Illionois, in two solar energy sessions. Topics covered include: thermal storage; solar cells; solar generation; biomass utilization; and solar energy applications. All papers are abstracted separately.
An algorithm has been developed and tested for steady-state liquid-liquid extraction, using recta... more An algorithm has been developed and tested for steady-state liquid-liquid extraction, using rectangular coordinates. It is capable of handling common types of stagewise contact, i.e. single stage extraction, multistage cross-current, and continuous countercurrent multistage extraction. The results depend on the nature of the extraction scheme and the extent of separation desired. While equilibrium data for some systems are stored in its data bank, the present portable computer simulator (LIQEXT) has the flexibility of reading equilibrium data for other systems, as well as overriding stored data.
This publication contains 12 papers of which 2 appear as abstracts only. The volume is based upon... more This publication contains 12 papers of which 2 appear as abstracts only. The volume is based upon papers presented at the 89th National AIChE Meeting, August 17-20, 1980, in Portland, Oregon and the 73rd AIChE Annual Meeting, held November 16-20 1980, in Chicago, Illionois, in two solar energy sessions. Topics covered include: thermal storage; solar cells; solar generation; biomass utilization; and solar energy applications. All papers are abstracted separately.
International Communications in Heat and Mass Transfer, 1989
It is possible to disperse high concentrations of finely pulverized beneficiated coal in water to... more It is possible to disperse high concentrations of finely pulverized beneficiated coal in water to produce a stable coal-water slurry fuel (CWF). One of the potential applications of CWF is as a fuel in gas turbines. This represents a relatively novel, developing technology. The gas ...
The major mode of heat transfer in industrial combustion furnaces is that of radiation. The effec... more The major mode of heat transfer in industrial combustion furnaces is that of radiation. The effects of radiative scattering are therefore of great importance in furnace design. This study investigates the behavior of both anisotropic and isotropic scattering using a computer-simulated model of a typical combustion furnaceThe furnace model employed is based on the zoning method of Hottel and the Monte-Carlo statistical approach. To study scattering effects, subroutines to simulate isotropic and anisotropic scattering have been added on to the model developed in earlier work with non-scattering mediums. Anisotropic scattering distributions studied include both forward and backward skewed profilesTo simplify the three-dimensional model, a three by four meter slab of a semi-infinite furnace is studied. Each stab is rectangular in shape, containing twelve cubical zones and incorporating a single burner. Model results are presented in the form of temperature contours and total surface heat fluxes for different scattering albedoes and profiles.
The development of a microcomputer based finite element program featuring phase change (melting a... more The development of a microcomputer based finite element program featuring phase change (melting and freezing) simulation and facilities is outlined. A closed form Galerkin finite element method derived from a delta function formulation of the latent heat discontinuity in the heat capacity versus temperature function is used within phase change elements of the solution domain. Storage reduction data structures are implemented and compared on the basis of overall program execution time. Analytical solutions for melting and freezing are used to vertify program accuracy and to explore other simulation parameters such as time step size, mesh density and start-up technique. Several ''life like'' phase change simulations are compared to the results obtained from other numerical models.
An investigation was undertaken to study the mixing of two miscible phases in coils by secondary ... more An investigation was undertaken to study the mixing of two miscible phases in coils by secondary flow and natural convection. In the absence of natural convection the Dean number was found to be a unique dynamic similarity parameter governing fluid flow and mixing in helical coils, even when the viscosities of the phases are very different. For fluids of differing densities natural convection increased the enhancements by as much as 58%. Mixing enhancement in segmented (i.e., gas partitioned) flow was typically three to four times larger than in nonsegmented flow. Various coil configurations were evaluated for enhancing the mixing. The change of coil curvature with coil length and the initial position of the interface relative to the direction of secondary flow were established as vital parameters affecting mixing.
Knowledge of the temperature profile of the gases produced by the combustion of fossil fuels with... more Knowledge of the temperature profile of the gases produced by the combustion of fossil fuels with air is a desirable step in the thermal protection systems. These gases are generally associated with high temperatures and steep temperature gradients. The measurement of temperature profiles of combustion products are often hard to make using thermocouples and other immersed pyrometers because such probes may have to be immersed in inaccessible and possibly destructive media. Determination of gas temperature profiles from multi-frequency radiative measurements seems an attractive alternative. This could be accomplished by radiative heat transfer probing and the application of the principle of inversion, where inversion is the process of inferring the internal parameters of a system of outside measurements, without the interruption of the combustion system itself.This paper discusses the development of models to retrieve the temperature distribution in a flame system by remote spectral sensing. Mixed Gray-Gas models were developed to calculate water vapor and carbon dioxide standard emissivities. The evaluation of combustion system spectral radiant flux was simulated and a model was developed and successfully tested for the application of temperature inversion.
The main sources of non-luminous gas radiation in furnaces are carbon dioxide and water vapor. Ap... more The main sources of non-luminous gas radiation in furnaces are carbon dioxide and water vapor. Approximation of the standard emissivities of water vapor and of carbon dioxide by mixed gray-gas model is studied. The model developed for carbon dioxide standard emi s si vi ti es covers a range of temperature of 3DO-1BOOK and a partial-pressure-length product range of 0.01 to 10 m atm. A mixture of six gray gases was adequate to cover the whole range. For the water vapor thermal radiation two models were developed to approximate the standard water ~apor emissi~ities. In the first model water ~apor is approximated by a mixture of four gray-gases and can be used in the temperature range of 300-700K and the partial-pressure-length range of 0.01 to 2 m atm. The second model is a piece-wise one in which one gray gas is used to cover the pL range 0.5-2 m and a second gray gas covered the range of 0.05-0.5 m. The model may be used in the temperature range of 700-l500K and has an error range of -2.3 to 3.7~.
... and TAREK A. ALLAM Deparrmenr of Chemical Engineering University of New Hampshire Durham, New... more ... and TAREK A. ALLAM Deparrmenr of Chemical Engineering University of New Hampshire Durham, New Hampshire 03824-3591 ... The knowledge of the emissivities of carbon dioxide and water vapor is very important in burner design and thermal efficiency calculations. ...
Bioprocess and Biosystems Engineering, Nov 22, 2000
In the present study the oxygen mass transfer from the gas to the aqueous phase in a Three-Phase ... more In the present study the oxygen mass transfer from the gas to the aqueous phase in a Three-Phase Inverse Fluidized Bed (TPIFB) has been studied. A pilot scale TPIFB has been designed and constructed. For determination of the volumetric oxygen mass transfer coefficient the elegant dynamic method, described by Dang et al. (1977) was used. The influence of hydrodynamic parameters,
This publication contains 12 papers of which 2 appear as abstracts only. The volume is based upon... more This publication contains 12 papers of which 2 appear as abstracts only. The volume is based upon papers presented at the 89th National AIChE Meeting, August 17-20, 1980, in Portland, Oregon and the 73rd AIChE Annual Meeting, held November 16-20 1980, in Chicago, Illionois, in two solar energy sessions. Topics covered include: thermal storage; solar cells; solar generation; biomass utilization; and solar energy applications. All papers are abstracted separately.
An algorithm has been developed and tested for steady-state liquid-liquid extraction, using recta... more An algorithm has been developed and tested for steady-state liquid-liquid extraction, using rectangular coordinates. It is capable of handling common types of stagewise contact, i.e. single stage extraction, multistage cross-current, and continuous countercurrent multistage extraction. The results depend on the nature of the extraction scheme and the extent of separation desired. While equilibrium data for some systems are stored in its data bank, the present portable computer simulator (LIQEXT) has the flexibility of reading equilibrium data for other systems, as well as overriding stored data.
This publication contains 12 papers of which 2 appear as abstracts only. The volume is based upon... more This publication contains 12 papers of which 2 appear as abstracts only. The volume is based upon papers presented at the 89th National AIChE Meeting, August 17-20, 1980, in Portland, Oregon and the 73rd AIChE Annual Meeting, held November 16-20 1980, in Chicago, Illionois, in two solar energy sessions. Topics covered include: thermal storage; solar cells; solar generation; biomass utilization; and solar energy applications. All papers are abstracted separately.
International Communications in Heat and Mass Transfer, 1989
It is possible to disperse high concentrations of finely pulverized beneficiated coal in water to... more It is possible to disperse high concentrations of finely pulverized beneficiated coal in water to produce a stable coal-water slurry fuel (CWF). One of the potential applications of CWF is as a fuel in gas turbines. This represents a relatively novel, developing technology. The gas ...
The major mode of heat transfer in industrial combustion furnaces is that of radiation. The effec... more The major mode of heat transfer in industrial combustion furnaces is that of radiation. The effects of radiative scattering are therefore of great importance in furnace design. This study investigates the behavior of both anisotropic and isotropic scattering using a computer-simulated model of a typical combustion furnaceThe furnace model employed is based on the zoning method of Hottel and the Monte-Carlo statistical approach. To study scattering effects, subroutines to simulate isotropic and anisotropic scattering have been added on to the model developed in earlier work with non-scattering mediums. Anisotropic scattering distributions studied include both forward and backward skewed profilesTo simplify the three-dimensional model, a three by four meter slab of a semi-infinite furnace is studied. Each stab is rectangular in shape, containing twelve cubical zones and incorporating a single burner. Model results are presented in the form of temperature contours and total surface heat fluxes for different scattering albedoes and profiles.
The development of a microcomputer based finite element program featuring phase change (melting a... more The development of a microcomputer based finite element program featuring phase change (melting and freezing) simulation and facilities is outlined. A closed form Galerkin finite element method derived from a delta function formulation of the latent heat discontinuity in the heat capacity versus temperature function is used within phase change elements of the solution domain. Storage reduction data structures are implemented and compared on the basis of overall program execution time. Analytical solutions for melting and freezing are used to vertify program accuracy and to explore other simulation parameters such as time step size, mesh density and start-up technique. Several ''life like'' phase change simulations are compared to the results obtained from other numerical models.
An investigation was undertaken to study the mixing of two miscible phases in coils by secondary ... more An investigation was undertaken to study the mixing of two miscible phases in coils by secondary flow and natural convection. In the absence of natural convection the Dean number was found to be a unique dynamic similarity parameter governing fluid flow and mixing in helical coils, even when the viscosities of the phases are very different. For fluids of differing densities natural convection increased the enhancements by as much as 58%. Mixing enhancement in segmented (i.e., gas partitioned) flow was typically three to four times larger than in nonsegmented flow. Various coil configurations were evaluated for enhancing the mixing. The change of coil curvature with coil length and the initial position of the interface relative to the direction of secondary flow were established as vital parameters affecting mixing.
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