The numerical simulation technique was employed to study the flow and heat transfer performance of the rotating cooling channel with feed chamber and impingement chamber. The discharge coefficient of the impingement h...
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The numerical simulation technique was employed to study the flow and heat transfer performance of the rotating cooling channel with feed chamber and impingement chamber. The discharge coefficient of the impingement holes and the average Nusselt number of the impingement target surface in the blade leading edge in rotating were obtained. The result shows that the Coriolis force induced by the rotation effect can change the discharge coefficient of the impingement holes. With the increase of the rotating speed, the Coriolis force effect becomes more obvious. The discharge coefficient increases with the increase of rotating Reynolds number and outflow ratio, and decreases with the increase of the inlet Reynolds number. The influence of the rotation on the average Nusselt number of the impingement target surface is not obvious. With the increase of the rotating speed, Nusselt number increases slightly only at high rotating speed.
The processing of interference fringe is the most important step in holographic interferometric technique. The interference fringe of mass diffusion were gathered and proposed, and 3 key steps in the process which red...
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The processing of interference fringe is the most important step in holographic interferometric technique. The interference fringe of mass diffusion were gathered and proposed, and 3 key steps in the process which reduce the precision mostly were improved in this paper. The improvements include the following steps: wavelet de-noise, frequency-domain wave filtering, phase unwrapping. The categories of noise were analyzed and some specific methods were used to reduce the noise. The improvements increased the precision greatly, and established a solid foundation for the using of laser holographic interferometric technique.
Based on the investigations on the influences of geometrical parameters and symmetrical plates disposal scheme on DMFC performance, a new scheme that staggered channels arrangement was presented and studied in this wo...
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Based on the investigations on the influences of geometrical parameters and symmetrical plates disposal scheme on DMFC performance, a new scheme that staggered channels arrangement was presented and studied in this work. The characteristics of fluid flow, proton transport and reaction rate distribution were well studied and contrasted to symmetrical scheme used in a cell unit. The effects of thickness of catalyst layer, backing layer and membrane on cell local average current density were investigated. After optimized design, a staggered scheme was put forward, and the higher potential output and greater limiting current density were obtained compared to the conventional symmetrical scheme. A new way to optimizing DMFC design and assembly was put forward.
In this paper, the statues and development trends of combustion research in internal combustion engines are discussed from several aspects. Some key issues in combustion of internal combustion engines are raised. The ...
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In this paper, the statues and development trends of combustion research in internal combustion engines are discussed from several aspects. Some key issues in combustion of internal combustion engines are raised. The combustion in internal combustion engines is a complex process with chemical reaction and energy conversion and there are still many aspects needed to be clarified, especially the chemical reaction mechanism and soot formation. Meanwhile, combustion diagnostic is playing an increasing role in the understanding of combustion. The motivation to deepen the research is the continuous requirement of high-efficiency and low-emission engines. Remarkable progress has been achieved in developing low-emission combustion concept like HCCI and low-temperature combustion. Alternative fuel engines become an important aspect in engine research and development. Advanced combustion technology combined with fuel control technology and after-treatment can realize the high-efficient and low-emission target.
A two-dimensional, steady-state model of a direct methanol fuel cell (DMFC) with liquid methanol feed was developed. The electrode kinetics, multi-component transport and methanol crossover phenomenon were all conside...
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A two-dimensional, steady-state model of a direct methanol fuel cell (DMFC) with liquid methanol feed was developed. The electrode kinetics, multi-component transport and methanol crossover phenomenon were all considered. The effect of channels disposal density, the influence of backing layer, catalyst layer and polymer electrolyte membrane thickness on mass transfer and cell performance was investigated. The results showed that: with the increase of channels disposal density and the increase of catalyst layer thickness, the equality of reaction rate and cell performance will elevated. The sizes of catalyst layer and membrane effect farthest, the correspondingly optimized work can increase the average current density about 131.0% and 17.8%. There are moderate optimal thickness sizes of backing layer and membrane, and the sizes should be chosen after thinking about the sizes of flow field plate and MEA.
In this paper, an experimental system for the measurement of mass diffusion coefficient using Michelson laser holographic Interferometry was designed and constructed. The experimental system include: the subsystem of ...
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In this paper, an experimental system for the measurement of mass diffusion coefficient using Michelson laser holographic Interferometry was designed and constructed. The experimental system include: the subsystem of Michelson interferometer, the diffusion cell for the mass diffusion of liquid-liquid, the subsystem of thermostatic water bath, the subsystem of image collecting and image processing. The mass diffusion coefficients of 0.33 molL-1 KCI solution with water at the temperature of 289.15 K were measured, and the result shows that the average of relative deviations is 1.30% compared with the literature values, and it verified the accuracy and reliability of the system. The mass diffusion coefficients of 0.1 molL-1 saccharose with water at 5 different temperature were measured, and the result shows that the biggest relative deviations is within 5% which verified the reliability of the system further.
Peanut shell,mixed with sodium carboxymethylcellulose,was gasified at a temperature of 450℃ and a pressure range from 24 to 27 MPa with the presence of different catalysts,including K2CO3,ZnCl2 and *** experimental r...
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Peanut shell,mixed with sodium carboxymethylcellulose,was gasified at a temperature of 450℃ and a pressure range from 24 to 27 MPa with the presence of different catalysts,including K2CO3,ZnCl2 and *** experimental results show that different catalysts have greatly different effects on the *** efficiency (GE),hydrogen gasification efficiency (GHE),carbon gasification efficiency (GCE),yield of hydrogen production (YH2) and potential yield of hydrogen production (YPH2) are applied to describe the catalytic *** the result of gaseous components,ZnCl2 has the highest hydrogen selectivity,K2CO3 is lower,and Raney-Ni is the lowest,but Raney-Ni is the most favorable to gasify biomass among the three catalysts,and its GE,GHE,GcE reach 126.84%,185.71%,94.24%,*** expected,hydrogen selectivity increased and CH4 reduced rapidly when the mixture of ZnCl2 and Raney-Ni is used under the same *** optimization mixture appeared when 0.2 g of ZnCl2 was added to 1 g of Raney-Ni,43.56 g·kg-1 of hydrogen production was *** addition,the catalytic mechanisms of different catalysts were analyzed,and the possible reaction pathway was brought forward,which helped to explain the experiment phenomena and results correctly.
The molten salt reactor (MSR), which is one of the generation IV reactors, can meet the demand of transmutation and breeding. The thermodynamic properties of the molten salt system like LiF-NaF-BeF2 influence the desi...
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The molten salt reactor (MSR), which is one of the generation IV reactors, can meet the demand of transmutation and breeding. The thermodynamic properties of the molten salt system like LiF-NaF-BeF2 influence the design and construction of the fuel salt and coolant in the MSR for the new generation. In this paper, the equation of state of the ternary system 15%LiF-58%NaF-27%BeF2, over the temperature range from 873.15 to 1 073.15 K at one atmosphere pressure, is described using a modified Peng-Robinson (PR) equation. The densities of the ternary system and its components are estimated by this equation directly, and compared with the experimental data. Based on the equation of state, the other thermodynamic properties such as the enthalpy, entropyand heat capacity at constant pressure are estimated by the residual function method and the fugacity coefficient method respectively. The densities calculated by PR equation are highly in agr eement with the experimental data, and the enthalpy, entropy and heat capacity evaluated by the two different methods are consistent with each other. It can be concluded that the modified PR equation can be applied to evaluate the density of the molten salt system, and it is recommended that it be used as the basis to estimate the enthalpy, entropy and heat capacity of the molten salt system.
Within the pressure range of 9-28 MPa,mass 200-500 kW/m2,experiments were performed to investigate the heat transfer to water in the inclined upward internally ribbed tube with an inclined angle of 19.5 degrees,a maxi...
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Within the pressure range of 9-28 MPa,mass 200-500 kW/m2,experiments were performed to investigate the heat transfer to water in the inclined upward internally ribbed tube with an inclined angle of 19.5 degrees,a maximum outer diameter of 38.1 mm,and a thickness of 7.5 *** on the experiments,it was found that heat transfer enhancement of the internally ribbed tube could postpone departure from nucleate boiling at the sub-critical ***,the heat transfer enhancement decreased near the critical *** supercritical pressure,the temperature difference between the wall and the fluid increased near the pseudo-critical temperature,but the increase of wall temperature was less than that of departure from nucleate boiling at sub-critical *** pressure is closer to the critical pressure,the temperature difference between the wall and the fluid increased greatly near the pseudo-critical *** transfer to supercritical water in the inclined upward internally ribbed tube was enhanced or deteriorated near the pseudo-critical temperature with the variety of ratio between the mass velocity and the heat *** the rotational flow of the internal groove reduced the effect of natural convection,the internal wall temperature of internally ribbed tube uniformly distributed along the *** maximum internal wall temperature difference of the tube along the circumference was only 10 degrees when the fluid enthalpy exceeded 2 000 J/*** the effect of acute variety of the fluid property on heat transfer,the correlation of heat transfer coefficient on the top of the internally ribbed tube was orovided.
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