A system has been established to conduct the experimental study of dynamic characteristics of shell-and-tube heat exchangers. Through experimental methods, an experimental study has been performed of the dynamic chara...
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A system has been established to conduct the experimental study of dynamic characteristics of shell-and-tube heat exchangers. Through experimental methods, an experimental study has been performed of the dynamic characteristics of heat exchangers with continuous spiral baffle plates, which have water and oil to serve as heat exchange working media. With the inlet flow disturbance representing equal percentage flow rate characteristics, studied were the dynamic responses to water and oil temperature at the outlet in four modes of flow rate disturbance. In the meantime, the effect of fluid disturbing quantity on the temperature rise at heat exchanger inlet and outlet at a certain Re number was also studied with a correlation equation between the temperature rise at the inlet and outlet of the heat exchanger and fluid disturbing quantity being obtained. The tests show that the dynamic response to the temperature of a liquid-liquid heat exchange system needs a comparatively long time. It has been found through the study that under a disturbance with a positive or negative flow rate, the change of temperature at the inlet and outlet of spiral-baffle plate heat exchangers assumes a linear relationship and the variation curve featuring temperature rise at the inlet and outlet has a symmetric feature at a positive or negative flow rate disturbance. A finite-difference numerical forecast model and artificial neural network one have been established respectively to dynamically forecast the outlet temperature at the heat exchanger oil side. The forecast results are in good agreement with the test values. The forecast results obtained from the neural network is better than those from the numerical simulation with the absolute value of the deviation being less than 1.3%, indicating that artificial neural network has a definite merit for engineering reference and applications when performing the discrimination of complicated systems.
Dioxins, emanating from the waste incineration, constitutes an organic pollutant that poses considerable risks to human health and environment. In this study, the corn straw char (CSC) and oak char (OC) derived from t...
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Biomass energy is renewable and rich in the world, providing a solution for the shortage in fossil fuel and serious environmental pollution. Proposing efficient utilization method of biomass waste demands urgent atten...
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An investigation was conducted of the flow distribution characteristics of distribution header water-wall tubes under a supercritical pressure for a home-made 600 MW once-through boiler. The test parameters can be lis...
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An investigation was conducted of the flow distribution characteristics of distribution header water-wall tubes under a supercritical pressure for a home-made 600 MW once-through boiler. The test parameters can be listed as follows: pressure p=23-25 MPa, mass flow rate G=400-1200 kg/(m2·s), working medium temperature t=10-400°C. An experimental study has been conducted of the impact of working medium pressure, mass flow rate and working medium temperature on the vertical water-wall tube flow distribution characteristics of the distribution header. The test results show that with an increase in mass flow rate, the uniformity of flow distribution among the vertical water-wall tubes could be enhanced. The non-uniformity of flow distribution will undergo a step increase near the quasi-critical points. Moreover, with an increasing pressure, the above-mentioned step increase will become weaker. By employing a discrete model of the parallel-connected branch tubes of the distribution header, the flow distribution among the distribution header vertical water-wall tubes was calculated and the calculation results are in good agreement with the test ones.
In this paper, a new numerical procedure is proposed for the steady flow of a viscous, incompressible fluid based on SIMPLER algorithm on a non-orthogonal non-staggered grid, together with Cartesian velocity component...
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In this paper, a new numerical procedure is proposed for the steady flow of a viscous, incompressible fluid based on SIMPLER algorithm on a non-orthogonal non-staggered grid, together with Cartesian velocity components as dependent variables in the momentum equations. The main feature of the algorithm is that the pressure and pressure correction equations are obtained by explicitly treating pressure cross-derivatives terms in interface contravariant velocities. A collocated arrangement of variables is introduced on numerical grids, and the cell face velocities are calculated by the momentum interpolation. It is proved that this algorithm can be effectively used to simulate fluid flow and heat transfer in complex geometry, by the validation calculation of flow inside branching channel.
The non-uniform distribution of reactants, pressure, temperature, and reaction rate, in a scaled-up proton exchange membrane fuel cell (PEMFC) can lead to different catalyst degradation rate, impacting the long-term p...
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This study is dedicated to solving the problems of low energy utilization and low yield in the conventional photocatalytic CO2 reduction process. In this work, a novel concentrated solar (light) reactor was establishe...
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The clean and efficient utilization of biomass waste for hydrogen production conforms to social development in the future. In this work, hydrogen production from supercritical water gasification (SCWG) of fir bark (FB...
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This study reconstructed the 3D structure for the gas diffusion layer (GDL) of proton exchange membrane fuel cells (PEMFCs) using the micro-CT technique and investigated the dynamic behavior of droplets inside the mul...
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The hydrophobicity of CeO2 surfaces is examined here. Since wettability measurements are extremely sensitive to experimental conditions, we propose a general approach to obtain contact angles between water and ceria s...
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