The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Yafang Cheng - One of the best experts on this subject based on the ideXlab platform.
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Technical note: Influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies
Atmospheric Chemistry and Physics, 2018Co-Authors: Uwe Kuhn, Hannah Meusel, Markus Ammann, Min Shao, Ulrich Pöschl, Yafang ChengAbstract:Abstract. Coated-wall flow tube reactors are frequently used to investigate gas uptake and heterogeneous or multiphase reaction kinetics under laminar flow conditions. Coating surface roughness may potentially distort the laminar flow pattern, induce Turbulence and introduce uncertainties in the calculated uptake coefficient based on molecular diffusion assumptions (e.g., Brown/Cooney–Kim–Davis (CKD)/Knopf–Poschl–Shiraiwa (KPS) methods), which has not been fully resolved in earlier studies. Here, we investigate the influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies. According to laminar boundary theory and considering the specific flow conditions in a coated-wall flow tube, we derive and propose a critical height δc to evaluate Turbulence effects in the design and analysis of coated-wall flow tube experiments. If a geometric coating thickness δg is larger than δc, the roughness elements of the coating may cause Local Turbulence and result in overestimation of the real uptake coefficient (γ). We further develop modified CKD/KPS methods (i.e., CKD-LT/KPS-LT) to account for roughness-induced Local Turbulence effects. By combination of the original methods and their modified versions, the maximum error range of γCKD (derived with the CKD method) or γKPS (derived with the KPS method) can be quantified and finally γ can be constrained. When Turbulence is generated, γCKD or γKPS can bear large difference compared to γ. Their difference becomes smaller for gas reactants with lower uptake (i.e., smaller γ) and/or for a smaller ratio of the geometric coating thickness to the flow tube radius (δg ∕ R0). On the other hand, the critical height δc can also be adjusted by optimizing flow tube configurations and operating conditions (i.e., tube diameter, length, and flow velocity), to ensure not only unaffected laminar flow patterns but also other specific requirements for an individual flow tube experiment. We use coating thickness values from previous coated-wall flow tube studies to assess potential roughness effects using the δc criterion. In most studies, the coating thickness was sufficiently small to avoid complications, but some may have been influenced by surface roughness and Local Turbulence effects.
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Technical Note: Influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies
2017Co-Authors: Uwe Kuhn, Hannah Meusel, Markus Ammann, Min Shao, Ulrich Pöschl, Yafang ChengAbstract:Abstract. Coated-wall flow tube reactors are frequently used to investigate gas uptake and heterogeneous or multiphase reaction kinetics under laminar flow conditions. Coating surface roughness may potentially distort the laminar flow pattern, induce Turbulence and introduce uncertainties in the calculated uptake coefficient based on molecular diffusion assumptions (e.g., Brown/CKD/KPS methods), which hasn't been sufficiently addressed in previous applications. Here we investigate the influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies. According to laminar boundary theory and considering the specific flow conditions in a coated-wall flow tube, we suggest using a critical height δc to evaluate Turbulence effects in the design and analysis of coated-wall flow tube experiments. When a coating thickness εmax is larger than δc, the roughness elements of the coating may cause Local Turbulence and result in overestimation of the real uptake coefficient (γ). We collect εmax values in previous coated-wall flow tube studies and evaluate their roughness effects using the criterion of δc. In most cases, the roughness doesn't generate Turbulence and has negligible effects. When Turbulence is generated, the calculated effective uptake coefficient (γeff) can bear large difference compared to the real uptake coefficient (γ). Their difference becomes less for gas reactants with lower uptake (i.e., smaller γ), or/and for a smaller ratio of the coating thickness εmax/R0 to the flow tube radius R0, (εmax/R0). On the other hand, the critical height δc can also be adjusted by optimizing flow tube configurations and operating conditions (i.e., tube diameter, length and flow velocity), to ensure not only an unaffected laminar flow pattern but also a flexible residence time of gas reactants in flow tube reactors.
Uwe Kuhn - One of the best experts on this subject based on the ideXlab platform.
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Technical note: Influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies
Atmospheric Chemistry and Physics, 2018Co-Authors: Uwe Kuhn, Hannah Meusel, Markus Ammann, Min Shao, Ulrich Pöschl, Yafang ChengAbstract:Abstract. Coated-wall flow tube reactors are frequently used to investigate gas uptake and heterogeneous or multiphase reaction kinetics under laminar flow conditions. Coating surface roughness may potentially distort the laminar flow pattern, induce Turbulence and introduce uncertainties in the calculated uptake coefficient based on molecular diffusion assumptions (e.g., Brown/Cooney–Kim–Davis (CKD)/Knopf–Poschl–Shiraiwa (KPS) methods), which has not been fully resolved in earlier studies. Here, we investigate the influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies. According to laminar boundary theory and considering the specific flow conditions in a coated-wall flow tube, we derive and propose a critical height δc to evaluate Turbulence effects in the design and analysis of coated-wall flow tube experiments. If a geometric coating thickness δg is larger than δc, the roughness elements of the coating may cause Local Turbulence and result in overestimation of the real uptake coefficient (γ). We further develop modified CKD/KPS methods (i.e., CKD-LT/KPS-LT) to account for roughness-induced Local Turbulence effects. By combination of the original methods and their modified versions, the maximum error range of γCKD (derived with the CKD method) or γKPS (derived with the KPS method) can be quantified and finally γ can be constrained. When Turbulence is generated, γCKD or γKPS can bear large difference compared to γ. Their difference becomes smaller for gas reactants with lower uptake (i.e., smaller γ) and/or for a smaller ratio of the geometric coating thickness to the flow tube radius (δg ∕ R0). On the other hand, the critical height δc can also be adjusted by optimizing flow tube configurations and operating conditions (i.e., tube diameter, length, and flow velocity), to ensure not only unaffected laminar flow patterns but also other specific requirements for an individual flow tube experiment. We use coating thickness values from previous coated-wall flow tube studies to assess potential roughness effects using the δc criterion. In most studies, the coating thickness was sufficiently small to avoid complications, but some may have been influenced by surface roughness and Local Turbulence effects.
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Technical Note: Influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies
2017Co-Authors: Uwe Kuhn, Hannah Meusel, Markus Ammann, Min Shao, Ulrich Pöschl, Yafang ChengAbstract:Abstract. Coated-wall flow tube reactors are frequently used to investigate gas uptake and heterogeneous or multiphase reaction kinetics under laminar flow conditions. Coating surface roughness may potentially distort the laminar flow pattern, induce Turbulence and introduce uncertainties in the calculated uptake coefficient based on molecular diffusion assumptions (e.g., Brown/CKD/KPS methods), which hasn't been sufficiently addressed in previous applications. Here we investigate the influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies. According to laminar boundary theory and considering the specific flow conditions in a coated-wall flow tube, we suggest using a critical height δc to evaluate Turbulence effects in the design and analysis of coated-wall flow tube experiments. When a coating thickness εmax is larger than δc, the roughness elements of the coating may cause Local Turbulence and result in overestimation of the real uptake coefficient (γ). We collect εmax values in previous coated-wall flow tube studies and evaluate their roughness effects using the criterion of δc. In most cases, the roughness doesn't generate Turbulence and has negligible effects. When Turbulence is generated, the calculated effective uptake coefficient (γeff) can bear large difference compared to the real uptake coefficient (γ). Their difference becomes less for gas reactants with lower uptake (i.e., smaller γ), or/and for a smaller ratio of the coating thickness εmax/R0 to the flow tube radius R0, (εmax/R0). On the other hand, the critical height δc can also be adjusted by optimizing flow tube configurations and operating conditions (i.e., tube diameter, length and flow velocity), to ensure not only an unaffected laminar flow pattern but also a flexible residence time of gas reactants in flow tube reactors.
Hannah Meusel - One of the best experts on this subject based on the ideXlab platform.
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Technical note: Influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies
Atmospheric Chemistry and Physics, 2018Co-Authors: Uwe Kuhn, Hannah Meusel, Markus Ammann, Min Shao, Ulrich Pöschl, Yafang ChengAbstract:Abstract. Coated-wall flow tube reactors are frequently used to investigate gas uptake and heterogeneous or multiphase reaction kinetics under laminar flow conditions. Coating surface roughness may potentially distort the laminar flow pattern, induce Turbulence and introduce uncertainties in the calculated uptake coefficient based on molecular diffusion assumptions (e.g., Brown/Cooney–Kim–Davis (CKD)/Knopf–Poschl–Shiraiwa (KPS) methods), which has not been fully resolved in earlier studies. Here, we investigate the influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies. According to laminar boundary theory and considering the specific flow conditions in a coated-wall flow tube, we derive and propose a critical height δc to evaluate Turbulence effects in the design and analysis of coated-wall flow tube experiments. If a geometric coating thickness δg is larger than δc, the roughness elements of the coating may cause Local Turbulence and result in overestimation of the real uptake coefficient (γ). We further develop modified CKD/KPS methods (i.e., CKD-LT/KPS-LT) to account for roughness-induced Local Turbulence effects. By combination of the original methods and their modified versions, the maximum error range of γCKD (derived with the CKD method) or γKPS (derived with the KPS method) can be quantified and finally γ can be constrained. When Turbulence is generated, γCKD or γKPS can bear large difference compared to γ. Their difference becomes smaller for gas reactants with lower uptake (i.e., smaller γ) and/or for a smaller ratio of the geometric coating thickness to the flow tube radius (δg ∕ R0). On the other hand, the critical height δc can also be adjusted by optimizing flow tube configurations and operating conditions (i.e., tube diameter, length, and flow velocity), to ensure not only unaffected laminar flow patterns but also other specific requirements for an individual flow tube experiment. We use coating thickness values from previous coated-wall flow tube studies to assess potential roughness effects using the δc criterion. In most studies, the coating thickness was sufficiently small to avoid complications, but some may have been influenced by surface roughness and Local Turbulence effects.
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Technical Note: Influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies
2017Co-Authors: Uwe Kuhn, Hannah Meusel, Markus Ammann, Min Shao, Ulrich Pöschl, Yafang ChengAbstract:Abstract. Coated-wall flow tube reactors are frequently used to investigate gas uptake and heterogeneous or multiphase reaction kinetics under laminar flow conditions. Coating surface roughness may potentially distort the laminar flow pattern, induce Turbulence and introduce uncertainties in the calculated uptake coefficient based on molecular diffusion assumptions (e.g., Brown/CKD/KPS methods), which hasn't been sufficiently addressed in previous applications. Here we investigate the influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies. According to laminar boundary theory and considering the specific flow conditions in a coated-wall flow tube, we suggest using a critical height δc to evaluate Turbulence effects in the design and analysis of coated-wall flow tube experiments. When a coating thickness εmax is larger than δc, the roughness elements of the coating may cause Local Turbulence and result in overestimation of the real uptake coefficient (γ). We collect εmax values in previous coated-wall flow tube studies and evaluate their roughness effects using the criterion of δc. In most cases, the roughness doesn't generate Turbulence and has negligible effects. When Turbulence is generated, the calculated effective uptake coefficient (γeff) can bear large difference compared to the real uptake coefficient (γ). Their difference becomes less for gas reactants with lower uptake (i.e., smaller γ), or/and for a smaller ratio of the coating thickness εmax/R0 to the flow tube radius R0, (εmax/R0). On the other hand, the critical height δc can also be adjusted by optimizing flow tube configurations and operating conditions (i.e., tube diameter, length and flow velocity), to ensure not only an unaffected laminar flow pattern but also a flexible residence time of gas reactants in flow tube reactors.
Min Shao - One of the best experts on this subject based on the ideXlab platform.
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Technical note: Influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies
Atmospheric Chemistry and Physics, 2018Co-Authors: Uwe Kuhn, Hannah Meusel, Markus Ammann, Min Shao, Ulrich Pöschl, Yafang ChengAbstract:Abstract. Coated-wall flow tube reactors are frequently used to investigate gas uptake and heterogeneous or multiphase reaction kinetics under laminar flow conditions. Coating surface roughness may potentially distort the laminar flow pattern, induce Turbulence and introduce uncertainties in the calculated uptake coefficient based on molecular diffusion assumptions (e.g., Brown/Cooney–Kim–Davis (CKD)/Knopf–Poschl–Shiraiwa (KPS) methods), which has not been fully resolved in earlier studies. Here, we investigate the influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies. According to laminar boundary theory and considering the specific flow conditions in a coated-wall flow tube, we derive and propose a critical height δc to evaluate Turbulence effects in the design and analysis of coated-wall flow tube experiments. If a geometric coating thickness δg is larger than δc, the roughness elements of the coating may cause Local Turbulence and result in overestimation of the real uptake coefficient (γ). We further develop modified CKD/KPS methods (i.e., CKD-LT/KPS-LT) to account for roughness-induced Local Turbulence effects. By combination of the original methods and their modified versions, the maximum error range of γCKD (derived with the CKD method) or γKPS (derived with the KPS method) can be quantified and finally γ can be constrained. When Turbulence is generated, γCKD or γKPS can bear large difference compared to γ. Their difference becomes smaller for gas reactants with lower uptake (i.e., smaller γ) and/or for a smaller ratio of the geometric coating thickness to the flow tube radius (δg ∕ R0). On the other hand, the critical height δc can also be adjusted by optimizing flow tube configurations and operating conditions (i.e., tube diameter, length, and flow velocity), to ensure not only unaffected laminar flow patterns but also other specific requirements for an individual flow tube experiment. We use coating thickness values from previous coated-wall flow tube studies to assess potential roughness effects using the δc criterion. In most studies, the coating thickness was sufficiently small to avoid complications, but some may have been influenced by surface roughness and Local Turbulence effects.
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Technical Note: Influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies
2017Co-Authors: Uwe Kuhn, Hannah Meusel, Markus Ammann, Min Shao, Ulrich Pöschl, Yafang ChengAbstract:Abstract. Coated-wall flow tube reactors are frequently used to investigate gas uptake and heterogeneous or multiphase reaction kinetics under laminar flow conditions. Coating surface roughness may potentially distort the laminar flow pattern, induce Turbulence and introduce uncertainties in the calculated uptake coefficient based on molecular diffusion assumptions (e.g., Brown/CKD/KPS methods), which hasn't been sufficiently addressed in previous applications. Here we investigate the influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies. According to laminar boundary theory and considering the specific flow conditions in a coated-wall flow tube, we suggest using a critical height δc to evaluate Turbulence effects in the design and analysis of coated-wall flow tube experiments. When a coating thickness εmax is larger than δc, the roughness elements of the coating may cause Local Turbulence and result in overestimation of the real uptake coefficient (γ). We collect εmax values in previous coated-wall flow tube studies and evaluate their roughness effects using the criterion of δc. In most cases, the roughness doesn't generate Turbulence and has negligible effects. When Turbulence is generated, the calculated effective uptake coefficient (γeff) can bear large difference compared to the real uptake coefficient (γ). Their difference becomes less for gas reactants with lower uptake (i.e., smaller γ), or/and for a smaller ratio of the coating thickness εmax/R0 to the flow tube radius R0, (εmax/R0). On the other hand, the critical height δc can also be adjusted by optimizing flow tube configurations and operating conditions (i.e., tube diameter, length and flow velocity), to ensure not only an unaffected laminar flow pattern but also a flexible residence time of gas reactants in flow tube reactors.
Ulrich Pöschl - One of the best experts on this subject based on the ideXlab platform.
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Technical note: Influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies
Atmospheric Chemistry and Physics, 2018Co-Authors: Uwe Kuhn, Hannah Meusel, Markus Ammann, Min Shao, Ulrich Pöschl, Yafang ChengAbstract:Abstract. Coated-wall flow tube reactors are frequently used to investigate gas uptake and heterogeneous or multiphase reaction kinetics under laminar flow conditions. Coating surface roughness may potentially distort the laminar flow pattern, induce Turbulence and introduce uncertainties in the calculated uptake coefficient based on molecular diffusion assumptions (e.g., Brown/Cooney–Kim–Davis (CKD)/Knopf–Poschl–Shiraiwa (KPS) methods), which has not been fully resolved in earlier studies. Here, we investigate the influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies. According to laminar boundary theory and considering the specific flow conditions in a coated-wall flow tube, we derive and propose a critical height δc to evaluate Turbulence effects in the design and analysis of coated-wall flow tube experiments. If a geometric coating thickness δg is larger than δc, the roughness elements of the coating may cause Local Turbulence and result in overestimation of the real uptake coefficient (γ). We further develop modified CKD/KPS methods (i.e., CKD-LT/KPS-LT) to account for roughness-induced Local Turbulence effects. By combination of the original methods and their modified versions, the maximum error range of γCKD (derived with the CKD method) or γKPS (derived with the KPS method) can be quantified and finally γ can be constrained. When Turbulence is generated, γCKD or γKPS can bear large difference compared to γ. Their difference becomes smaller for gas reactants with lower uptake (i.e., smaller γ) and/or for a smaller ratio of the geometric coating thickness to the flow tube radius (δg ∕ R0). On the other hand, the critical height δc can also be adjusted by optimizing flow tube configurations and operating conditions (i.e., tube diameter, length, and flow velocity), to ensure not only unaffected laminar flow patterns but also other specific requirements for an individual flow tube experiment. We use coating thickness values from previous coated-wall flow tube studies to assess potential roughness effects using the δc criterion. In most studies, the coating thickness was sufficiently small to avoid complications, but some may have been influenced by surface roughness and Local Turbulence effects.
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Technical Note: Influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies
2017Co-Authors: Uwe Kuhn, Hannah Meusel, Markus Ammann, Min Shao, Ulrich Pöschl, Yafang ChengAbstract:Abstract. Coated-wall flow tube reactors are frequently used to investigate gas uptake and heterogeneous or multiphase reaction kinetics under laminar flow conditions. Coating surface roughness may potentially distort the laminar flow pattern, induce Turbulence and introduce uncertainties in the calculated uptake coefficient based on molecular diffusion assumptions (e.g., Brown/CKD/KPS methods), which hasn't been sufficiently addressed in previous applications. Here we investigate the influence of surface roughness and Local Turbulence on coated-wall flow tube experiments for gas uptake and kinetic studies. According to laminar boundary theory and considering the specific flow conditions in a coated-wall flow tube, we suggest using a critical height δc to evaluate Turbulence effects in the design and analysis of coated-wall flow tube experiments. When a coating thickness εmax is larger than δc, the roughness elements of the coating may cause Local Turbulence and result in overestimation of the real uptake coefficient (γ). We collect εmax values in previous coated-wall flow tube studies and evaluate their roughness effects using the criterion of δc. In most cases, the roughness doesn't generate Turbulence and has negligible effects. When Turbulence is generated, the calculated effective uptake coefficient (γeff) can bear large difference compared to the real uptake coefficient (γ). Their difference becomes less for gas reactants with lower uptake (i.e., smaller γ), or/and for a smaller ratio of the coating thickness εmax/R0 to the flow tube radius R0, (εmax/R0). On the other hand, the critical height δc can also be adjusted by optimizing flow tube configurations and operating conditions (i.e., tube diameter, length and flow velocity), to ensure not only an unaffected laminar flow pattern but also a flexible residence time of gas reactants in flow tube reactors.
