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During the combustion of straw, the formation of deposition, which destines to furnace erosion and exerts great influence on safety operation, on heating surface is affected by many factors. The paper studies the influence of speed and amount of air. According to the test: the air speed affects the sedimentary quantity of fly ash and the deposition position; the air amount affects the fuel combustion...
The decomposition of sulfur hexafluoride (SF6) in overheated electric equipment at different temperature in low humidity was simulated in the study. SF6 is very stable and not significantly decomposed at 200°C, 250°C and 300°C. SF6 is significantly decomposed at 350°C. SF6 is more easily to be decomposed and decomposed more rapidly at higher temperature.
Steam pipelines play an important role in industrial enterprises. They joint the heat producer and users, and constitute the energy transmission networks. The total cost on steam pipelines include the expense of steel and heat insulator, converted expense of heat loss, and construction cost. This study develops a mathematical model of total cost on steam pipelines with golden section algorithm. The...
Heat release analysis in diesel engines is a powerful method to investigate the combustion process and engine performance. The aim of this study is to simulate the heat release rate during combustion using the measured in-cylinder pressure based on thermodynamic principles. After determining the submodels such as mass and composition, gas and fuel properties, heat of combustion, heat loss to the walls,...
This paper designed and described a Helmholtz-type valveless self-excited pulse combustor with continuous fuel and air supply. Its structure is similar to the conventional Helmholtz type's, but valves are not used. The operational characteristics of the Helmholtz-type valveless self-excited pulse combustor was investigated by the experiment. The effects of the excess air ratio, tailpipe length and...
The technology of horizontal-tube falling film evaporation is widely used in low temperature multi-effect distillation evaporators. The heat transfer coefficient of it depends on many factors, such as steam velocity, sprinkle density, evaporation temperature, etc. In the engineering design of evaporator, much smaller sprinkle density may led to "dry points on tube", while much bigger sprinkle...
Laminar natural convection arising from horizontal rectangle cylinder to its concentric cylindrical enclosure is numerically studied. The Rayleigh number is varied in the range of 103≤Ra≤106. According to the form of isotherms and the streamline patterns, the basic features of flow and heat transfer for four rectangle cylinders with different aspect ratios are reported. And the local and average Nusselt...
In this paper, two typical Chinese coals were selected to investigate the pulverized coal combustion characteristic and their pore structure evolution in oxy-fuel combustion and conventional air combustion environment with a drop tube furnace (DTF). Results show that the burn-off rate of pulverized coal in O2/CO2 mixtures is lower than that in O2/N2 environment with equivalent oxygen concentration...
Pyrolysis of a single biomass particle is numerically studied using a one-dimensional model which assumes virgin material decomposes through three parallel reactions to light gases, tar and char. In contrast to most past studies in which the heat of pyrolysis is assumed to be endothermic throughout the process, this paper presents a new method of calculating the pyrolysis heat in the simulation of...
Aiming at the aircraft fuel system which adopts the technology of vapor cycle cooling system, and uses the fuel as a kind of effective cold source of condensers and other heat exchangers, this paper established the mathematical models of the fuel system and major components. On the basis of Simulink software platform, the simulation module of fuel system was established by developing the S-functions...
Abstract-Simultaneous transport of heat and moisture by conjugate natural convection in an enclosure with a solid wall and two free ports is investigated numerically. Moist air motions are driven by the external temperature and concentration differences imposed across enclosures with different ambient moisture conditions. The Prandtl number and Schmidt number used are 0.7 and 0.6 respectively. The...
The reaction of a Chinese bituminous coal PDS with Fe2O3 was investigated by such experimental means as thermogravimetric (TGA) coupled with Fourier transform infrared spectroscopy (FTIR) and TGA-difference thermal analysis (DTA) with focus on the effect of the heating rate. It was found that the reaction of PDS with Fe2O3 displayed three-staged reaction characteristics, and a higher heating rate...
In order to accurately know the temperature field around a fixed anchorage and the heat loss of buried pipe we used the numerical simulation technology to simulate the temperature field in fixed anchorage of buried heating pipes, then, we got the intuitive temperature distribution figure and the size of heat loss. The simulation results indicate the necessity of effective insulation measures for fixed...
Groundwater source heat pump system has great impact on the temperature of groundwater for a long-term. According to the continuity equations, motion equations and energy equations of fluid cylindrical coordinate system and the boundary conditions of pumping production and injection well, the forced convection in turbulent flows model of smooth cylinder has been established. Consider three ways of...
This paper presents a steady-state simulation study of oxy-fuel gas cycle power plant with CO2 amine absorption process using process software Aspen HYSYS™. The oxy-fuel gas cycle power plant studied was decomposed to four units: the air separation unit (ASU), the gas turbine cycle, the heat recovery steam generator (HRSG) and the CO2 capture process. Based on the steady-state simulations, the energy...
According to the basic law of energy conservation and conversion, the energy consumption evaluation indexes of two basic research objects in oil-gas gathering and transferring system, i.e. stations and pipelines, are established. On the basis of that, the energy consumption evaluation indexes for the whole system are obtained through mean weighted method. Then heat loss rate and pressure loss rate...
Low temperature thermal treatment of poly chlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/PCDFs) in fly ash from commercial-scale medical waste incinerator (MWI) was studied experimentally using a quartz tubular heating system. Experiments were carried out in nitrogen atmosphere at different temperatures, i.e. 250, 300, 350, and 400°C, for two heating times (45 and 90 min)....
The pyrolysis of cornstalk was studied by using Pyris-ITGA thermogravimetric apparatus with the heating rates of 20, 40, 60, 80, 100K/min and final temperature of 1073 K. Through the analysis of TG and DTG, the results show that the pyrolysis process of cornstalk includes four steps: drying, pre-pyrolysis, mainpyrolysis and carbonization; As the heating rate increased, both the maximum pyrolysis rate...
The maximum principal stress, von Mises equivalent stress, equivalent creep strain in dissimilar welded joints between martensitic heat-resistant steel (T91) and bainitic heat-resistant steel (G102) are simulated by FEM under the conditions of 833K and inner pressure of 28MPa. The results show that the maximum principal stress and von Mises equivalent stress are quit high in the vicinity of weld/G102...
In this paper, changes of thermal conductivity of paraffin mixtures joined different percentages of aluminum, copper, silicon powder were stuPdied. Feasibility of adding these three kinds of powders into paraffin to enhance paraffin's thermal properties was studied, as well as the influence of different addictives on paraffin's phase-change temperature and latent heat. The results showed that adding...
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