Advanced Materials Research Vols. 732-733

Abstract: CAES (Compressed Air Energy Storage) is an energy storage method which preserves electric energy in the form of air pressure potential energy. As the storage space, the internal air pressure of air reservoir significantly affects the performance of the CAES system. Based on a thorough study of variable pressure air reservoir of CAES, this paper puts forward a thermodynamic modeling method which could be perfectly applied in air pressure and temperature variation analysis. Modeling parameters are fitted by serving Huntorf power plant in Germany as reference case; results show that the obtained pressure curves match the actual curves, which in turn demonstrate the high accuracy of the model presented. By comparing different pressures under several working conditions, it is clear that alternately air releasing and air inflation effectively reduce throttling loss and the energy consumption of compressor, also system efficiency is improved.

Abstract: Optimum working conditions of 11 working fluids under different heat source temperatures in an organic Rankine cycle were systematically investigated. Cycle efficiency of each fluid was compared at their optimal operating conditions were then analyzed. R141b appears to be the best choice when the heat source temperature is around 200oC. Heptane is suggested the suitable working fluids for the ORC system when the heat source is 300oC.

Abstract: In order to solve the ill-posed problem in 3D acoustic temperature field reconstruction, the paper proposed a new modified singular value decomposition (SVD) method.According to their reliability ,singular values were divided into three parts and got various degree of modification respectively. To verify the performance of the new algorithm based on the modified SVD method,two model temperature fields were reconstructed when the signal-to-noise ratio (SNR) of sound flight-time data was 50dB , 40dB and 30dB respectively.And the results were compared with those based on routine Truncated singular value decomposition (TSVD) and Tikhonov methods. Simulation results show that the new algorithm has higher precision, better anti-noise ability than the routine methods and it is more suitable for the complex temperature fields reconstruction, thus it is expected to be used for temperature field reconstruction on-line.

Abstract: The distributions of exergy dissipation in a 1000MW coal-fired power plant under different operation conditions were analyzed. Mass and energy balance models of different components were constructed to determine the thermodynamic properties of each stream. A variant of exergy analysis, the proposed equivalent specific fuel consumption (ESFC) analysis, were conducted to determine the additional specific fuel consumptions (ASFC) of individual component and, therefore, to obtain the characteristic of its temporal and spatial distribution. The off-design modeling of main components was established. The methodology and results of analysis in this paper can be taken as valuable guidance for the optimal design and operation of thermal power plants and for the improvement and retrofits for more cost-effective and environmental-friendly power plants.

Abstract: Based on experimental studies, this paper discusses the variation tendencies of three non-dimensional parameters including Ja, Bo and Pr which consist of various operational parameters and characteristic parameters, and then analyses their effects on heat transfer performance of closed-loop pulsating heat pipes (PHPs) at startup stage and steady operation stage. Results indicate that at startup stage, the values of Ja and Bo increase over time as a whole, while the values of Pr decrease; at steady operation stage, the values of three parameters all fluctuate within a narrow range. The results also show that heat transfer is due mainly to the exchange of latent heat under the experimental conditions.

Abstract: A tangentially fired boiler with twin furnace is tested to analyze the effect of such factors as primary air velocity,air distribution mode, over fired air,oxygen content on NOx and boiler efficiency during boiler combustion adjustment,providing reference for boiler operation optimization and reducing NOx emissions.

Abstract: Influences of void ratio of glass fiber cloth, conductivity of glass fiber cloth, number of of insulation layer and emissivity of aluminium foil on apparent heat conductivity of vacuum heat insulation oil pipe are calculated based on the experiment plat in master machinery plant of Liaohe Petroleum Exploration Bureau. The results show that apparent heat conductivity of vacuum heat insulation oil pipe is inverse ratio to void ratio of glass fiber cloth, and is proportional to conductivity of glass fiber cloth and emissivity of aluminium foil. At vacuum condition, 6 layers is appropriate.

Abstract: With a long natural cooling time after a shutdown of steam turbine restricting its available coefficient, this paper presented the analysis and application of a forced cooling process to sub-critical steam turbine. The radiating mechanism of natural cooling was analyzed theoretically, and the required amount of cooling air was calculated for a WH 600MW steam turbine. Moreover, the cooling rate with no life loss principle was determined by the method of quantitative calculation and numerical analysis, together with safety analysis. The research discussed the control strategy of practical application according with steam turbine characteristic and applied to operation, which provided theoretical guidance for the optimization of cooling condition.

Abstract: The technology of downstream vibrated bed dryer with high temperature flue gas has been applied successfully by CPI Mengdong Energy Group Co., LTD for the large scale upgrading of Baiyinhua lignite. It is very necessary to study the drying process of a single lignite particle by high temperature flue gas. Based on finite volume method, the numerical simulation was applied in the lignite drying process and the mathematical model for the drying process of a single spherical lignite particle with high temperature flue gas was developed. Here, the lignite particle was divided into dry region and wet region by water evaporation interface. To accelerate convergence and make stable domain larger and truncation error smaller in the solution process, Crank-Nicolson six-point difference iteration method was used to solve the model.

Abstract: In order to understand the characteristics of fire whirls in the inclined shaft with corner gap, large eddy simulations (LES) of thermal flow field in a 9-meter-high inclined shaft were employed. In the inclined shaft, the conrner gap is 0.3m and 0.7m in width, and the inclination angle is 5°, 30°, 45°, 50° and 55° from the vertical orientation axes respectively. It is found that a whirling flow field could be formed under proper inclination angles and corner gap width. Rotational axis of fire whirls in the inclined shaft would have same inclination angles with the shaft. Similar to the case of fire whirls in a vertical shaft, the width of corner gap of inclined shaft also influences the whirling motion of the flame. In this paper, for the same fire and inclination angle, the 0.3-meter-wide corner gap is easier to form stable fire whirls than the 0.7-meter-wide corner gap. By comparison with buoyancy, the slightly greater Coriolis force was found above a height 3m for inclined fire whirls when the width of croner gap is 0.3m, however, the Coriolis force acts only on the lower part of the shaft when the width of croner gap is 0.7m.