Advanced Materials Research Vols. 614-615

Abstract: The gas-solid multi-phase flow is measured in a 300MW down-fired bolier cold model with swirl burners by two-dimensional phase Doppler velocimetry(PDA), concluded the influence of different outer secondary air vane angles on the multi-phase flow characteristics in the furnace. For vane angles of 25°, the vertical direction average velocity is high and fluctuating velocity is low, the reach of the downward airflow is deeper, primary air and secondary air mix slowly, the horizontal direction average velocity is high and fluctuating velocity is low, solid phased particles spread slowly and mix with the rewind air weakly, this is against to the ignition of pulverized coal. For vane angles of 35°, the vertical direction average velocity decrease and decay faster, fluctuating velocity increase slightly, the horizontal direction average velocity and fluctuating velocity increased slightly, solid phased particles spread quickly and mixed with the rewind air quickly, the ignition of pulverized coal increase. For vane angles of 55°, the recirculation zone appear in the burner nozzle region, the vertical direction fluctuating velocity increase significantly, average velocity decrease and decay quickly, the downward airflow turn upwards before mixing with gas, the horizontal direction average velocity high and fluctuating velocity is higher, solid phased particles spread more quickly, mixed with the rewind air more quickly, this will erode the water wall and throat, cause the water wall slagging. Considering various factors, the best outer secondary air vane angle is 35° in the operation of boiler.

Abstract: What the paper describes is to develop the performance calculation program and it will be used in the practical unit through analyzing the thermal process in the power plant, which is on the basis of the operation performance of the power plant equipment and the analysis of the calculation method in accordance with the first law of thermodynamics. We can be analyzed through calculating and quantifying the performance of the whole boiler, the turbine, the thermodynamic system and the power plant in detail. The operation quality and the intact degree of unit equipment can be evaluated by the operation personnel according to performance data. Finally, it is going to save energy reduce consumption, and realize the goal of improving level of the unit operation.

Abstract: A flowing and heat transfer model of superheated steam has been established. Thermal calculation of high-quality wet steam injectors of Du84-54-160 and Du84-60-58 in Block Shu-1 and data analysis of part of the pipelines of SAGD-2# steam injection station have been completed with this model. The results and the actual data match very well with each other.

Abstract: Based on the heat and mass transfer theory and characteristics of the CFD software, a three-dimensional numerical simulation platform had been developed to study the thermal performance in a natural draft wet cooling tower. This platform was validated using the measured results of a running cooling tower. The flow and temperature field in the cooling tower were investigated. It is found that the water temperature and flow field can be correctly calculated using this platform. The cooling efficiency could be improved due to non-uniform fill and water distribution methods.

Abstract: As for the time-dependent behavior of the fuel heat and mass evaporation transfer progress on hot surface,consider the convective mass transfer and heat transfer, the liquid-gas two-phase flow of continuous heat transfer model was studied. By the dimensionless transform, the time-dependent behavior of the concentration distribution and the temperature field was obtained. The result of n-Heptanes evaporation transfer progress on hot surface experiment is consistent with the academic model.

Abstract: Heat transfer and flow characteristics in the microchannel cooling passages with three different types of the MTPV systems are numerically investigated. This investigation covers Reynolds number in the range of 100 to 1000 and heat flux ranged from 50kW/m² to 150kW/m². The steady, laminar flow and heat transfer equations are solved in a finite-volume method. Results such as temperature distribution, heat transfer coefficient, pressure drop and friction factor are reported. A comparison of the heat transfer coefficient and friction factor of the different microchannels are also presented. The heat transfer performance of the rod bundles microchannel is found to be much better than others. Both friction factor and heat transfer coefficient are increased as the Reynolds number increased.

Abstract: To prevent and dispose all kinds of problems occurred in the air preheaters of the large coal-fired power plants and improve the performance of the air preheaters, the representative problems of the air preheaters in Henan province was summarized with the statistical method. With specific cases, its adverse impact for boilers and auxiliary machines were analyzed. The main reasons for causing these problems were design flaws, maintain undeserved, poor blowing effect and high sulfur content in coal that can cause acid corrosion to the air preheaters. A series of countermeasures were put forward to resolve the problems.

Abstract: Flow of evaporating thin liquid film containing insoluble surfactant on a uniformally heated substrate is considered in this paper. Coupled nonlinear evolution equations for the film thickness and surfactant concentration are derived on the base of lubrication theory and reasonable boundary conditions. The flow stability of the thin liquid film has been studied using normal mode method according to the linear stability theory. The results show that the film stability is promoted by increasing the Capillary number and the surfactant Peclet number, while increasing the Marangoni number, the interface resistance number, the vapor recoil number and the evaporation number can reduce the stability of the system.

Abstract: In the current paper, under the condition of different flue gas temperatures and constant flue gas thermal power, the influence of different organic working fluids on the efficiency of sub-critical organic Rankine cycle system were studied. The efficiency and other parameters of the simple system were calculated. The results show that the efficiency of sub-critical organic Rankine cycle system could reach maximum when the parameters of the working fluids in the expander inlet are dry-saturation. Flammability, toxicity, ozone depletion and other factors of the working fluids should be considered in the organic Rankine cycles. R245fa is considered a better choice for low-temperature heat source power generation, and the efficiency of the system is about 10.2%; for the high-temperature heat source, R601a can be considered; however, due to its high flammability, novel working fluids should be further discovered for power generation.

Abstract: Numerical simulation was carried out for the ventilation performance of a Trombe wall driven by thermal pressure. The effect of heat flux, the wall width and height to the indoor ventilation were analyzed and discussed. The results show that the increase of heat flow and the height of wall cause the increase of natural ventilation rate while the increase of width cause the increase of ventilation and then deceasing.