Advanced Materials Research Vols. 516-517

Abstract: The paper is focused on the present situation and the development of large-scale circulating fluidized bed (CFB) boilers. Several developed technology of CFB such as supercritical and ultra supercritical pressure CFB boilers for power plants, oxy-fuel CFB boiler for CO2 capture and high-density circulating fluidized bed gasifier for advanced IGCC/IGFC are introduced in this paper.

Abstract: The energy characterization method of friction sensitivity about high-burning rate solid propellant, which identified by 50% explosion probability was studied, and it was verified in the practical application. This method solved the problems about the conventional test methods can not be compared with similar formulations friction degree.

Abstract: A model of thermal management for cooling system of aero-piston engine was presented in this study. The models of main parts in this system were also founded. Based on the measured value of temperature and pressure in the cylinder, the heat transfer coefficient between gas-fired and the cylinder wall was calculated by using the empirical formula. A heat transfer boundary condition between fins and cooling air was determined according to various Reynolds number of the air flow. Moreover, the method of finite element analysis was utilized to calculate the temperature of cylinder block. In the specified working condition of some two-stroke piston engine used in the unmanned aerial vehicle (UAV), the calculation and analysis were made to study on the effect of aircrew speed and flight height on the cylinder block temperature, as well as the effect of cylinder block temperature on airscrew speed by the thermal management model. The calculation results show that, as the flight height rises, the cylinder block temperature increases accordingly when engine power and airscrew speeds are kept constant; however, at the same height, the higher the airscrew speed is, the lower cylinder block temperature will be. The cylinder block temperature should be kept stable by regulating the airscrew speed.

Abstract: Abstract: With the help of field experiments, a 1-D/3-D coupled simulation model between automo-tive engine cooling systems and engine cabin is established. Through these experiments and coupled simulations, the influence of engine cabin on the performance of engine cooling system and thermal flow field has been analyzed, and convective heat transfer coefficients on the engine surface which contacted with engine cabin’s thermal flow field have been summarized. These heat transfer coeffi-cients provide basic arguments for developing engine cooling system efficiently.

Abstract: Firstly, the limitation of using simplified model to design thermal generating unit controller is discussed. For the simplified model, the dynamic of the synchronous generator is neglected, and thus it is not valid in the emergency state of power systems. Secondly, the integral model of thermal generating unit is constructed, which consists of the models of boiler, turbine and synchronous generator. Compared with the simplified model, the integral model can accurately describe the rotor storage characteristic of thermal generating unit. Thirdly, a new energy balance controller is designed based on the constructed integral model. In the new controller the derivative of rotor speed is feed-forwarded, and thus the controller can respond to the energy imbalance more quickly, and the dynamic of steam pressure can be enhanced obviously. Finally, the simulation results also demonstrate the validity of the proposed controller.

Abstract: Since the molecular force and the molecular volume were ignored in the ideal gas model, and it was less accurate when the ideal gas model was used to depict characteristics of real gas under high pressure, so the real gas model was adopted and the heat transfer was considered, the dynamic variation model was set up for internal gas in the pressure vessel during loading operation. The model was solved by using the numerical simulation method of Runge-Kutta. Comparison was made between the ideal gas model and the real gas model under adiabatic and non-adiabatic conditions, it showed that under low pressure the results obtained by the two models were in good agreement, but under high pressure the deviation was enlarged, the real gas model with considering the heat transfer influenced would be more coincident with the reality.

Abstract: This paper presents a method of a new system of heating vulcanizing machine by heat transfer oil, it is a system that based on neural network of fuzzy temperature control. One one hand, compared with the traditional PI control of relative ratio, we can make a conclusion that in the heating system of fuzzy control, the heating system robustness could be enhanced. One the other hand, through the analysis of the simulation results, this programme guarantees the stability of heating system and emission the temperature fluctuation which is caused by heating plate. The last but not the least, we can take these advantages and control the system easier.

Abstract: Coal particles are supplied to drop tube furnace (DTF) with a designed shaftless screw micro feeder. The condition of individual particles in furnace, which demands small particles size (10²μm) and low flow rate for micro feeder，is desired to reaction mechanisms research. When particle size is less than 1mm, the interparticle forces such as van der Waals interactions have enormous effect on flow behavior of particles, so it is difficult to provide continuous and steady particles flow at low flow rate. In this paper, the micro feeder uses shaftless spring as its feeding element. To simulate dispersed particles flow, the feeding rate of coal particles should be decided by feeding coefficient M and is controlled by variable rotation speed of screw. The corresponding simplified model of feeding rate is presented, and interparticle forces are evaluated by the velocity coefficient . A vibrating metal rod is inserted into the middle of the shaftless screw to avoid particles agglomeration, and particle flow stability is also effectively improved. The given results show good linearity and stability of micro feeder. Moreover, the influences of the particle properties such as particle size and particle moisture content on the feeding rate are also investigated.

Abstract: Based on mass balance, energy balance and chemical equilibrium, a theoretical gasification index model for actual fuel gasified with air and air/steam was established considering the key reactions of ultimate compositions in the fuel. The model can be used to predict the gasification index, such as the syngas composition, the syngas calorific value, gasification efficiency and syngas yield. The theoretical gasification indexes of some coal and biomass were obtained by this model. The simulated results show that: For the actual fuel, the syngas calorific value for air gasification is lower than that for air/steam gasification, and the syngas calorific value from coal is lower than that from biomass, whereas the syngas yield from coal is higher than that from biomass.

Abstract: Four types of heat sources of a dynamic lithium-ion battery (LIB) during charge were studied, and temperature distributions inside the dynamic LIB caused by the four kinds of heat generation sources with different currents and temperatures during charge were simulated by using a electrochemical-thermal three-dimensional model. The ohmic heat is the largest heat resource with about 63.5% in the total heat generation during regular charge, the electrochemical reaction heat is dominant when the SOC is below around 10%, and the subsidiary reaction heat can not be ignored when the temperature in the battery is above 80°C. Current as well as ambient temperature plays a very important role in the overall thermal behaviors of the battery.