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Same Operating Conditions (same + operating_condition)
Selected AbstractsAssessment of fire protection performance of water mist applied in exhaust ducts for semiconductor fabrication processFIRE AND MATERIALS, Issue 5 2005Yi-Liang Shu Abstract Fume exhaust pipes used in semiconductor facilities underwent a series of fire tests to evaluate the performance of a water mist system. The parameters considered were the amount of water that the mist nozzles used, the air flow velocity, the fire intensity and the water mist system operating pressure. In order to make a performance comparison, tests were also performed with a standard sprinkler system. The base case served as a reference and applied a single water mist nozzle (100 bar operating pressure, 7.3 l/min water volume flux and 200 µm mean droplet size) installed in the pipe (60 cm in diameter) subjected to a 350°C air flow with an average velocity of 2 m/s. In such a case, the temperature in the hot flow dropped sharply as the water mist nozzle was activated and reached a 60°C saturation point. Under the same operating conditions, four mist nozzles were applied, and made no further contribution to reducing the fire temperature compared with the case using only a single nozzle. Similar fire protection performances to that in the base case were still retained when the exhaust flow velocity increased to 3 m/s and the inlet air temperature was increased to 500°C due to a stronger input fire scenario, respectively. Changing to a water mist system produced a better performance than a standard sprinkler. With regard to the effect of operating pressure of water mist system, a higher operating pressure can have a better performance. The results above indicate that the droplet size in a water-related fire protection system plays a critical role. Copyright © 2005 John Wiley & Sons, Ltd. [source] The performance analysis of a two-stage transcritical CO2 cooling cycle with various gas cooler pressuresINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2008Arif Emre Özgür Abstract A theoretical analysis of a two-stage transcritical CO2 cooling cycle is presented. The effect of a two-stage cycle with intercooling process on the system coefficient of cooling performance is presented for various gas cooler pressures. However, the performance comparison between one-stage and two-stage cycles is presented for same operating conditions. Gas cooler pressure, compressor isentropic efficiency, gas cooler efficiency, intercooling quantity and refrigerant outlet temperature from the gas cooler are used as variable parameters in the analysis. It is concluded that the performance of the two-stage transcritical CO2 cycle is approximately 30% higher than that of the one-stage transcritical CO2 cycle. Hence, the two-stage compression and intercooling processes can be assumed as valuable applications to improve the transcritical CO2 cycle performance. Copyright © 2008 John Wiley & Sons, Ltd. [source] Theoretical and experimental comparison of the performance of a single-stage heat transformer operating with water/lithium bromide and water/CarrolÔINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 8 2002W. Rivera This paper compares under the same operating conditions, the theoretical and experimental performance of a single-stage heat transformer operating with the water/lithium bromide and the water/CarrolÔ mixtures, where CarrolÔ is a mixture of lithium bromide and ethylene glycol [(CH2OH)2] in the ratio 1:4.5 by weight patented by Carrier Corp. Flow ratios, gross temperature lifts, useful heat, and coefficients of performance are plotted for the heat transformer against temperatures and solution concentrations. Because the water/CarrolÔ mixture has higher solubility than water/lithium bromide and high experimental values were obtained for the gross temperature lift, it seems to be a better alternative mixture to be used in absorption heat transformers. Copyright © 2002 John Wiley & Sons, Ltd. [source] Preparation of sorbitol from D -glucose hydrogenation in gas,liquid,solid three-phase flow airlift loop reactorJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 4 2004Jian-Ping Wen Abstract A new process for D -glucose hydrogenation in 50 wt% aqueous solution, into sorbitol in a 1.5 m3 gas,liquid,solid three-phase flow airlift loop reactor (ALR) over Raney Nickel catalysts has been developed. Five main factors affecting the reaction time and molar yield to sorbitol, including reaction temperature (TR), reaction pressure (PR), pH, hydrogen gas flowrate (Qg) and content of active hydrogen, were investigated and optimized. The average reaction time and molar yield were 70 min and 98.6% under the optimum operating conditions, respectively. The efficiencies of preparation of sorbitol between the gas,liquid,solid three-phase flow ALR and stirred tank reactor (STR) under the same operating conditions were compared. Copyright © 2004 Society of Chemical Industry [source] Four beds pressure swing adsorption for hydrogen purification: Case of humid feed and activated carbon bedsAICHE JOURNAL, Issue 9 2009Ana M. Ribeiro Abstract The novelty of this manuscript is the study of purification of hydrogen from a mixture of H2/CO2/CH4/CO/N2 saturated in water vapor. Simulations results of fixed bed behavior and of an eight steps PSA process are presented using an activated carbon as adsorbent. Several operating conditions were considered, namely different feed flow rates, humid/dry feed and adiabatic/nonadiabatic operation. Simulation with single column PSA showed that a 99.9979% purity hydrogen stream could be obtained with a recovery of 71.3% and a productivity of 63.9 mol/kgads/day. The simulation of a four columns PSA predicted a decrease in H2 purity to 99.8193% for the same operating conditions, due to the impurities present in the recycled stream of the continuous multicolumn process. To increase the hydrogen purity above 99.99%, the feed time was decreased 25%. Thus, the multicolumn simulation predicted a hydrogen recovery, purity, and productivity, respectively, of 62.7%, 99.9992%, and 55.2 mol/kgads/day. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Experimental Simulation of the Reactor Section of Fluid Cokers: Comparison of FCC and Fluid Coke ParticlesTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2006Xuqi Song Abstract The hydrodynamics of fluid cokers were studied in a pressurized fully cylindrical cold model of diameter 483 mm, geometrically and dynamically scaled down by a factor of ,20 from commercial units. Differential pressure fluctuations, voidage distributions, solids momentum flux distributions and steady state gas mixing behaviour in the reactor section are compared for the same operating conditions with two kinds of particles, FCC and fluid coke. The voidage distributions and core-annular flow structures in the reactor section were similar enough that either FCC or fluid coke particles can be used for cold modelling of fluid cokers. On a étudié l'hydrodynamique d'unités de cokéfaction fluide dans une maquette froide cylindrique pressurisée de 483 mm de diamètre, géométriquement et dynamiquement réduite d'un facteur 20 par rapport à des unités commerciales. Les fluctuations de pression différentielles, les distributions de vide, les distributions de flux de moment des solides et le comportement de mélange de gaz à l'état stable dans la section du réacteur sont comparés pour les mêmes conditions opératoires avec deux sortes de particules, soient FCC et coke fluide. Les distributions de vide et les structures d'écoulement noyau-espace annulaire dans la section du réacteur sont suffisamment semblables pour que des particules de FCC ou de coke fluide puissent être utilisées pour la modélisation à froid d'unités de cokéfaction fluide. [source] Solar membrane natural gas steam-reforming process: evaluation of reactor performanceASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010M. De Falco Abstract In this work, the performance of an innovative plant for efficient hydrogen production using solar energy for the process heat duty requirements has been evaluated via a detailed 2D model. The steam-reforming reactor consists of a bundle of coaxial double tubes assembled in a shell. The annular section of each tube is the reaction zone in which Ni-based catalyst pellets are packed, whereas the inner tube is a dense Pd-based selective membrane that is able to remove hydrogen from the reaction zone. By coupling reaction and hydrogen separation, equilibrium constrains inside the reactor are circumvented and high methane conversions at relatively low temperatures are achieved. The heat needed for the steam-reforming reaction at this low operating temperature can be supplied by using a molten salt stream, heated up to 550 °C by a parabolic mirror solar plant, as heating fluid. The effects on membrane reactor performance of some operating conditions, as gas mixture residence time, reaction pressure and steam-to-carbon ratio, are assessed together with the enhancement of methane conversion with respect to the traditional process, evaluated in the range 40.5,130.9% at the same operating conditions. Moreover, owing to the use of a solar source for chemical process heat duty requirements, the greenhouse gases (GHG) reduction is estimated to be in the range 33,67%. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Cybernetic Modeling and Regulation of Metabolic Pathways in Multiple Steady States of Hybridoma CellsBIOTECHNOLOGY PROGRESS, Issue 5 2000Maria Jesus Guardia Hybridoma cells utilize a pair of complementary and partially substitutable substrates, glucose and glutamine, for growth. It has been shown that cellular metabolism shifts under different culture conditions. When those cultures at different metabolic states are switched to a continuous mode, they reach different steady states under the same operating conditions. A cybernetic model was constructed to describe the complementary and partial substitutable nature of substrate utilization. The model successfully predicted the metabolic shift and multiple steady-state behavior. The results are consistent with the experimental observation that the history of the culture affects the resulting steady state. [source] | |||||||||||||