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Fischer-Tropsch synthesis (FTS) is a highly exothermic reaction with challenging heat transfer is... more Fischer-Tropsch synthesis (FTS) is a highly exothermic reaction with challenging heat transfer issues. Enhanced heat transfer has been realized by using microfibrous entrapped catalysts (MFEC) to perform FTS in fixed bed reactors. Pseudo-homogeneous thermal conductivities greater than 9 W/m-K have been obtained using MFEC made from highly conductive copper fibers. Much larger tubes can be used for FTS using Cu-MFEC than is possible using packed beds of extrudates. 2D (r,z) Simulations and recent experiments indicate that tubes as large as 100 mm ID can safely be used for this highly exothermic reaction without danger of runaway. The pseudo-homogeneous thermal conductivity of MFEC made from copper, nickel or stainless steel without flow correlates with the electrical conduction through the sintered metal matrix in terms of a junction factor. In flowing conditions the pseudo-homogeneous thermal conductivity increases linearly with the Reynolds number. This behavior is investigated by ...
Highly exothermic and highly endothermic reactions require catalyst beds with good heat transfer ... more Highly exothermic and highly endothermic reactions require catalyst beds with good heat transfer characteristics. A novel structured catalyst, Microfibrous Entrapped Catalyst Structure (MFEC) made of highly thermal conductive metals can significantly improve heat transfer efficiency, compared with traditional packed beds (PB). Firstly, the thermal parameters of metal MFEC were determined experimentally. In a stagnant N2 gas test, the radial effective thermal conductivity of Cu MFEC is 56-fold of that of alumina PB, while the inside wall heat transfer coefficient is 10 times of that of alumina PB. Compared to PB, even made of pure copper particles, conductive metal MFEC also provides much more effective thermal conductivity and higher inside wall heat transfer coefficient in a flowing gas test. In addition, an application of Cu MFEC in Fischer-Tropsch Synthesis (FTS), demonstrated the improvement of temperature distribution inside the catalyst bed and the increase of product selectiv...
Microfibrous Entrapped Catalyst (MFEC) made of copper has radial effective thermal conductivity 9... more Microfibrous Entrapped Catalyst (MFEC) made of copper has radial effective thermal conductivity 9.05W/m-K in stagnant gas, which is fifty six times of that of alumina PB, 0.16 W/m-K, while the inside wall heat transfer coefficient of it is 235W/m2-K, ten times of that of alumina PB, 22.7W/m2-K. Therefore, the intra-bed heat transfer of fixed bed reactor can be greatly enhanced by using Cu MFEC as catalyst support. To avoid the copper poison from tradition method, a novel method to load catalyst into MFEC structure was developed by entrapping pre-manufacture catalyst particle into sintered fiber mesh. This method promises a high potential for the application of Cu MFEC in many heterogeneous highly exothermic or highly endothermic reactions, such as hydrogenation, stream reforming, partial oxidation and so on. The application of this catalyst structure in Fischer-Tropsch Synthesis is a good example. The new catalyst loading method makes Co/Al2O3catalyst totally copper free, which is a...
1st International Energy Conversion Engineering Conference (IECEC), 2003
ABSTRACT Understanding flow through microfibrous sintered materials is important for design of de... more ABSTRACT Understanding flow through microfibrous sintered materials is important for design of devices such as Stirling engine regenerators that employ microfibrous materials. A recent theoretical advance, the "Porous Media Permeability Equation"1,2 describes the permeability of porous materials over the entire range of possible bed voidages. In this model the form drag parameter is the ratio of viscous form drag to viscous friction losses for a homogeneous material, which only depends on bed voidage. Previously, prediction of the permeability of high voidage materials has been done by correlating experimental data with bed voidage, but this new design equation accurately predicts the pressure drop versus face velocity relationship for any bed voidage when the shape factor and angle of flow paths are known.
40th International Conference on Environmental Systems, 2010
SAE Technical Paper Series, 1999
International Journal of Heat and Mass Transfer, 2013
ABSTRACT A modified resistance network model, the junction factor model, is developed to predict ... more ABSTRACT A modified resistance network model, the junction factor model, is developed to predict the effective thermal conductivity of sintered microfibrous materials (MFM) made of conductive metals. It contains two characteristic variables: metal volume fraction (y) and junction factor (ϕ). The junction factor representing the fibers’ connection quality can be easily determined by the measurement of electrical resistance, so this model provides a practical and convenient method to estimate the effective thermal conductivity of sintered MFM. Moreover, various methods to improve the junction factor and the effective thermal conductivity of copper MFM are investigated. High sintering temperatures and long sintering times increase both the junction factor and effective thermal conductivity of MFM. Electroplating and impregnation methods were also employed to enhance the junction conductivity. Electroplating provides a significant improvement in the junction factor and the effective thermal conductivity of the media.
Industrial & Engineering Chemistry Research, 2014
Industrial & Engineering Chemistry Research, 2013
Applied Catalysis A: General, 2012
Fischer-Tropsch synthesis (FTS) is a highly exothermic reaction with challenging heat transfer is... more Fischer-Tropsch synthesis (FTS) is a highly exothermic reaction with challenging heat transfer issues. Enhanced heat transfer has been realized by using microfibrous entrapped catalysts (MFEC) to perform FTS in fixed bed reactors. Pseudo-homogeneous thermal conductivities greater than 9 W/m-K have been obtained using MFEC made from highly conductive copper fibers. Much larger tubes can be used for FTS using Cu-MFEC than is possible using packed beds of extrudates. 2D (r,z) Simulations and recent experiments indicate that tubes as large as 100 mm ID can safely be used for this highly exothermic reaction without danger of runaway. The pseudo-homogeneous thermal conductivity of MFEC made from copper, nickel or stainless steel without flow correlates with the electrical conduction through the sintered metal matrix in terms of a junction factor. In flowing conditions the pseudo-homogeneous thermal conductivity increases linearly with the Reynolds number. This behavior is investigated by ...
Highly exothermic and highly endothermic reactions require catalyst beds with good heat transfer ... more Highly exothermic and highly endothermic reactions require catalyst beds with good heat transfer characteristics. A novel structured catalyst, Microfibrous Entrapped Catalyst Structure (MFEC) made of highly thermal conductive metals can significantly improve heat transfer efficiency, compared with traditional packed beds (PB). Firstly, the thermal parameters of metal MFEC were determined experimentally. In a stagnant N2 gas test, the radial effective thermal conductivity of Cu MFEC is 56-fold of that of alumina PB, while the inside wall heat transfer coefficient is 10 times of that of alumina PB. Compared to PB, even made of pure copper particles, conductive metal MFEC also provides much more effective thermal conductivity and higher inside wall heat transfer coefficient in a flowing gas test. In addition, an application of Cu MFEC in Fischer-Tropsch Synthesis (FTS), demonstrated the improvement of temperature distribution inside the catalyst bed and the increase of product selectiv...
Microfibrous Entrapped Catalyst (MFEC) made of copper has radial effective thermal conductivity 9... more Microfibrous Entrapped Catalyst (MFEC) made of copper has radial effective thermal conductivity 9.05W/m-K in stagnant gas, which is fifty six times of that of alumina PB, 0.16 W/m-K, while the inside wall heat transfer coefficient of it is 235W/m2-K, ten times of that of alumina PB, 22.7W/m2-K. Therefore, the intra-bed heat transfer of fixed bed reactor can be greatly enhanced by using Cu MFEC as catalyst support. To avoid the copper poison from tradition method, a novel method to load catalyst into MFEC structure was developed by entrapping pre-manufacture catalyst particle into sintered fiber mesh. This method promises a high potential for the application of Cu MFEC in many heterogeneous highly exothermic or highly endothermic reactions, such as hydrogenation, stream reforming, partial oxidation and so on. The application of this catalyst structure in Fischer-Tropsch Synthesis is a good example. The new catalyst loading method makes Co/Al2O3catalyst totally copper free, which is a...
1st International Energy Conversion Engineering Conference (IECEC), 2003
ABSTRACT Understanding flow through microfibrous sintered materials is important for design of de... more ABSTRACT Understanding flow through microfibrous sintered materials is important for design of devices such as Stirling engine regenerators that employ microfibrous materials. A recent theoretical advance, the "Porous Media Permeability Equation"1,2 describes the permeability of porous materials over the entire range of possible bed voidages. In this model the form drag parameter is the ratio of viscous form drag to viscous friction losses for a homogeneous material, which only depends on bed voidage. Previously, prediction of the permeability of high voidage materials has been done by correlating experimental data with bed voidage, but this new design equation accurately predicts the pressure drop versus face velocity relationship for any bed voidage when the shape factor and angle of flow paths are known.
40th International Conference on Environmental Systems, 2010
SAE Technical Paper Series, 1999
International Journal of Heat and Mass Transfer, 2013
ABSTRACT A modified resistance network model, the junction factor model, is developed to predict ... more ABSTRACT A modified resistance network model, the junction factor model, is developed to predict the effective thermal conductivity of sintered microfibrous materials (MFM) made of conductive metals. It contains two characteristic variables: metal volume fraction (y) and junction factor (ϕ). The junction factor representing the fibers’ connection quality can be easily determined by the measurement of electrical resistance, so this model provides a practical and convenient method to estimate the effective thermal conductivity of sintered MFM. Moreover, various methods to improve the junction factor and the effective thermal conductivity of copper MFM are investigated. High sintering temperatures and long sintering times increase both the junction factor and effective thermal conductivity of MFM. Electroplating and impregnation methods were also employed to enhance the junction conductivity. Electroplating provides a significant improvement in the junction factor and the effective thermal conductivity of the media.
Industrial & Engineering Chemistry Research, 2014
Industrial & Engineering Chemistry Research, 2013
Applied Catalysis A: General, 2012