The Experts below are selected from a list of 197742 Experts worldwide ranked by ideXlab platform
Adel A Hegazy - One of the best experts on this subject based on the ideXlab platform.
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performance of flat plate solar air heaters with optimum channel geometry for constant variable Flow Operation
Energy Conversion and Management, 2000Co-Authors: Adel A HegazyAbstract:This study extends the applicability of the analytical criterion developed for estimating optimum channel geometry of conventional solar air heaters (SAHs) to other flat plate types. Assessment is made for two other basic types with Flow over the absorber and on both sides of it. Heater performance characteristics are analytically determined over a wide range of channel depth-to-length ratios (D/L) and are compared with those of the conventional type, having a Flow channel under the absorber. The effects of air mass Flow rate, emissivity of channel plates and wind heat transfer coefficient on the accuracy of the criterion are also investigated. For these two SAHs, the criterion is found to be equally valid as it predicts the optimal (D/L) ratio that yields best performance. Further, the ratio of D/L=2.5×10−3 represents the criterion simplified version for variable Flow Operation.
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optimum channel geometry for solar air heaters of conventional design and constant Flow Operation
Energy Conversion and Management, 1999Co-Authors: Adel A HegazyAbstract:Abstract The study presents a remarkably simple criterion for determining the channel optimum depth-to-length ratio ( D / L ) opt which effectively maximizes the useful energy from collectors that are designed to heat a fixed mass rate of air Flow. The engineering accuracy of the analytically derived criterion has been corroborated over a wide range of ambient variables, design parameters and operating conditions. The results demonstrate clearly the decisive role of the ( D / L ) ratio in enhancing heater performance. A poor choice of this ratio can significantly affect the thermal conversion efficiency, especially for lower specific mass rates. In contrast, decreasing the ( D / L ) ratio beyond the optimal value leads to a slight enhancement in heater efficiency. Of significance is the finding that, by choosing ( D / L ) opt , we maximize also the air temperature rise. For variable Flow Operation, however, the ratio of D / L =2.5×10 −3 is recommended as the optimal. Moreover, the reported results and discussions have provided valuable conceptual insights regarding generalization of the performance curves of conventional solar air heaters. It is found that the analytically determined channel depth parameter, in conjunction with the air specific mass rate, are quite successful in correlating the performance in general terms.
Krzysztof Gosiewski - One of the best experts on this subject based on the ideXlab platform.
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homogeneous vs catalytic combustion of lean methane air mixtures in reverse Flow reactors
Chemical Engineering Science, 2008Co-Authors: Krzysztof Gosiewski, Yurii Sh Matros, Krzysztof Warmuzinski, M Jaschik, Marek TanczykAbstract:To carry out a comparative assessment of a recently proposed idea of using thermal Flow-reversal reactors (TFRR) for mine ventilation air, the results for the catalytic Flow-reversal reactor (CFRR) investigated within the European Project (2003) are briefly presented. Next, experimental investigations of thermal combustion are presented in this paper. These consisted of the kinetic study of homogeneous combustion in the pelletized bed and in the monolith. Kinetic equations for the two cases are derived and discussed. Experimental autothermal reverse-Flow Operation in a laboratory setup was performed. Due to the high heat capacity of the wall and insulation of the pelletized bed reactor, with considerable heat losses to the surroundings, autothermal Operation was successful only in the monolithic reactor. It is finally concluded that the thermal combustion can be competitive compared with the catalytic oxidation.
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homogeneous vs catalytic combustion of lean methane air mixtures in reverse Flow reactors
Chemical Engineering Science, 2008Co-Authors: Krzysztof Gosiewski, Yurii Sh Matros, Krzysztof Warmuzinski, M Jaschik, Marek TanczykAbstract:To carry out a comparative assessment of a recently proposed idea of using thermal Flow-reversal reactors (TFRR) for mine ventilation air, the results for the catalytic Flow-reversal reactor (CFRR) investigated within the European Project (2003) are briefly presented. Next, experimental investigations of thermal combustion are presented in this paper. These consisted of the kinetic study of homogeneous combustion in the pelletized bed and in the monolith. Kinetic equations for the two cases are derived and discussed. Experimental autothermal reverse-Flow Operation in a laboratory setup was performed. Due to the high heat capacity of the wall and insulation of the pelletized bed reactor, with considerable heat losses to the surroundings, autothermal Operation was successful only in the monolithic reactor. It is finally concluded that the thermal combustion can be competitive compared with the catalytic oxidation.
Ho-ming Yeh - One of the best experts on this subject based on the ideXlab platform.
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Recovery of deuterium from water-isotope mixture by thermal diffusion in countercurrent-Flow flat-plate Frazier scheme with optimum plate spacing
Progress in Nuclear Energy, 2010Co-Authors: Ho-ming YehAbstract:Abstract The effect of plate spacing on the degree of recovery and production rate for deuterium recovery from water–isotope mixture in flat-plate thermal diffusion columns of countercurrent-Flow Frazier scheme with fixed Operation expense, has been investigated. The equations for estimating optimum plate spacing for maximum recovery and maximum production rate have been derived. Considerable improvement in performance is obtainable when thermal diffusion columns with optimum plate spacing are employed for Operation. The fact that countercurrent-Flow Operation is more effective than cocurrent-Flow Operation for the recovery of deuterium in a Frazier scheme, is also confirmed.
Marek Tanczyk - One of the best experts on this subject based on the ideXlab platform.
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homogeneous vs catalytic combustion of lean methane air mixtures in reverse Flow reactors
Chemical Engineering Science, 2008Co-Authors: Krzysztof Gosiewski, Yurii Sh Matros, Krzysztof Warmuzinski, M Jaschik, Marek TanczykAbstract:To carry out a comparative assessment of a recently proposed idea of using thermal Flow-reversal reactors (TFRR) for mine ventilation air, the results for the catalytic Flow-reversal reactor (CFRR) investigated within the European Project (2003) are briefly presented. Next, experimental investigations of thermal combustion are presented in this paper. These consisted of the kinetic study of homogeneous combustion in the pelletized bed and in the monolith. Kinetic equations for the two cases are derived and discussed. Experimental autothermal reverse-Flow Operation in a laboratory setup was performed. Due to the high heat capacity of the wall and insulation of the pelletized bed reactor, with considerable heat losses to the surroundings, autothermal Operation was successful only in the monolithic reactor. It is finally concluded that the thermal combustion can be competitive compared with the catalytic oxidation.
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homogeneous vs catalytic combustion of lean methane air mixtures in reverse Flow reactors
Chemical Engineering Science, 2008Co-Authors: Krzysztof Gosiewski, Yurii Sh Matros, Krzysztof Warmuzinski, M Jaschik, Marek TanczykAbstract:To carry out a comparative assessment of a recently proposed idea of using thermal Flow-reversal reactors (TFRR) for mine ventilation air, the results for the catalytic Flow-reversal reactor (CFRR) investigated within the European Project (2003) are briefly presented. Next, experimental investigations of thermal combustion are presented in this paper. These consisted of the kinetic study of homogeneous combustion in the pelletized bed and in the monolith. Kinetic equations for the two cases are derived and discussed. Experimental autothermal reverse-Flow Operation in a laboratory setup was performed. Due to the high heat capacity of the wall and insulation of the pelletized bed reactor, with considerable heat losses to the surroundings, autothermal Operation was successful only in the monolithic reactor. It is finally concluded that the thermal combustion can be competitive compared with the catalytic oxidation.
Miquel A Pericas - One of the best experts on this subject based on the ideXlab platform.
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enantioselective continuous Flow production of 3 indolylmethanamines mediated by an immobilized phosphoric acid catalyst
Chemistry: A European Journal, 2014Co-Authors: Laura Osorioplanes, Carles Rodriguezescrich, Miquel A PericasAbstract:A polystyrene-supported 1,1’-bi-2-naphthol derived phosphoric acid has been synthesized and applied in the enantioselective Friedel–Crafts reaction of indoles and sulfonylimines. The immobilized catalyst was highly active and selective, and gave rise to a broad range of 3-indolylmethanamines (19 examples) in high yields and excellent enantioselectivities (up to 98 % enantiomeric excess) after short reaction times under very convenient reaction conditions (RT in dichloromethane). Moreover, repeated recycling (14 cycles) was possible with no substantial loss in catalytic performance and the system could be adapted to a continuous-Flow Operation (6 h). Finally, the applicability of the system was further confirmed by rapid access to a library of compounds with three points of diversity in a single continuous-Flow experiment that involved sequential pumping of different substrate combinations.
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asymmetric α amination of aldehydes catalyzed by ps diphenylprolinol silyl ethers remediation of catalyst deactivation for continuous Flow Operation
ChemInform, 2013Co-Authors: Xinyuan Fan, Sonia Sayalero, Miquel A PericasAbstract:The newly synthesized polystyrene supported diphenylprolinol silyl ether is used as a highly active catalyst for the enantioselective α-amination of aldehydes.
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asymmetric α amination of aldehydes catalyzed by ps diphenylprolinol silyl ethers remediation of catalyst deactivation for continuous Flow Operation
Advanced Synthesis & Catalysis, 2012Co-Authors: Xinyuan Fan, Sonia Sayalero, Miquel A PericasAbstract:Polystyrene (PS)-supported diphenylprolinol silyl ethers have been developed as highly active catalysts for the enantioselective α-amination of aldehydes. Understanding the mechanism of catalyst deactivation has led to the development of reaction conditions notably extending catalyst life in repeated recycling (10 cycles; accumulated TON of 480) and has allowed the implementation of a continuous Flow α-amination process (6 min residence time, 8 h Operation).