Advanced Materials Research Vols. 538-541

Abstract: We used the industrial gas waste heat as the heat source of low-temperature floor radiant heating system to save energy and protect our environment, which is the thing that predecessors didn’t do. So we designed heat exchangers, which are the key parts of them, and accurately calculated their heat transfer area by using the method of ε-NTU. Through temperature drop and pressure of the gas changed, we compared their variable quantity, and draw the conclusion that improving the temperature and pressure can reduce it effectively. Using this technology, we can save 30000 tons of anthracite into a heating season , which is worth ￥24,000,000 or so, in the resident sub-district ,whose heating building area of 10000 m2, so the practical application of it has very well prospect, and the research based on it has strong economic significance and social significance.

Abstract: Failure cause analysis was carried out on tee joint crack of boiler platen superheater header (12Cr1MoV) of subcritical power station applying microanalysis, mechanical properties test, chemical composition analysis, metallography examination and SEM observation etc. Results indicated that the tee joint crack originated at the original defects, connected with reheat cracks during propagation and led to leakage finally. The improper structure, the original welding defects, overhigh welding heat input, and excessive welding residual stress resulted in the leakage failure.

Abstract: In range of high pressure, the performance of two stage compression cycle with an expander (TSCE+IC) is better than the two stage cycle with an intercooler (TSCC+IC). In the cycle (TSCE+IC), the optimum discharge temperature is 42°C and the highest COP is 3.3, in the cycle (TSCC+IC), the optimum discharge temperature is 50°C and the highest COP is 3.07. In the cycle (TSCC+IC), the optimum intermediate pressure is 5.8MPa and the highest COP is 3.08, in the cycle (TSCE+IC), the optimum intermediate pressure is 6.2MPa and the highest COP is 3.33. With increasing of evaporating temperature or decreasing outlet temperature of gas cooler, the performance of cycle (TSCE+IC) or cycle (TSCC+IC) is an increasing trend. Under the same conditions, expander cycle performance superior to the throttle valve performance. Some fundamental data were obtained for improving cycle performance and developing the products of CO2 refrigeration air condition and heat pumps.

Abstract: The effect of heat input on toughness of coarse-grained heat-affected zone of an ultra low carbon acicular ferrite steel were investigated when the welding was conducted with high heat input. Microstructural observations, energy dispersive X-ray spectroscopy analyses were conducted using optical microscopy, scanning electron microscopy and transmission electron microscopy, respectively. The microstructures of coarse-grained heat-affected zone consist of predominantly bainitic microstructure and a small proportion of acicular ferrite grains. The bainitic microstructures become coarsened with increasing heat input. The impact toughness of coarse-grained heat-affected zone remained at a higher level when the heat input ranged from 42 to 55 kJ/cm. It became not stable and dropped to a lower level when the heat input increased to 110150 kJ/cm. The enhancement in impact toughness was attributable to the MnS precipitation on the pre-formed Ti oxides as well as the formation of intragranular ferrite. When specimens were welded with higher heat input, the deterioration of impact toughness was caused by the coarsening of austenite grains.

Abstract: The technology of spontaneous heating is a new method of deicing and melting snow.It puts electrical conductor into asphalt concrete.After electrical conductor sending out heat,temperature of pavement will be increased.Untill temperature is higher than freezing point,ice and snow will be melted.According to theory of heating,a model of finite element is designed.Based on ANSYS,temperature field of pavement layer and temperature distribution of pavement surface,ascending rule of temperature,warm-up time,affection of deicing and snow-melting are researched.Finally,curved line and analyzed result of deicing and melting snow are received.The result can demonstrate the feasibility of technology of spontaneous heating to deice and melt snow on airport pavement.

Abstract: With the heightened concern for energy consumption and environment conservation, the interest on fuel cell HEV (hybrid electric vehicle) has been greatly increased. In this study, a numerical model for the cooling system of batteries was constructed. Using the constructed analysis model, the material of the cartridge and the cartridge width were checked for improving the performance of the cooling system of batteries. The performance was changed by using different cartridge material, and the cartridge width also has an effect to the performance of the cooling system of batteries as shown in the analysis results. The constructed model and method can be used to investigate the performance of the cooling system of batteries.

Abstract: A hybrid power composed of fuel cell and MH-Ni battery has become a good strategy for HEV, but the battery cooling system can not be easily optimized because of many important parameters. In this study, the parameter studies have been carried out for checking the effects of the parameters. The candidated parameters in this study were the diameter of the outlets and the distance between the outlets. The analysis results show that the diameter and the distance have the effects expressed by a 2nd order function form. The analysis model and the results in this study make a basis for optimizing the battery cooling system.

Abstract: The effect of varying heat inputs (20, 100, 200 kJ/cm) on the microstructures and toughness of the simulated coarse-grained heat-affected zone of a Nb-Ti microalloyed pipeline steel were investigated utilizing optical and electron microscope. Results showed that the impact toughness of the coarse-grained heat-affected zone maintained a higher level at the heat input of 20 and 100 kJ/cm, whereas it dropped to a much lower level at the heat input of 200 kJ/cm. The good toughness was attributed to the grain refinement and the homogenous distribution of fine and elongated martensite/austenite constituents. The deterioration of toughness for high heat input simulated welding was mainly caused by the coarse bainitic microstructure and massive martensite/austenite constituents.

Abstract: Using simulating and field experiment to analyze the influence of secondary cooling scheme for wide slab on the quality of blank, to find the theory for quality defect, develop new methods for better qualityblank, and try to make a way to improve quality level of blank.

Abstract: A hybrid power composed of the fuel cell and MH-Ni battery has become a good strategy for HEV, but the performance of the battery cooling systems can not be easily adjusted. In this study, heat flux of the batteries and mass flow rate of cooling air have been investigated to improve the performance of a battery cooling system. As shown in the results, the error of root mean square has been decreased under the condition of decreasing heat flux of the batteries, and the performance of the battery cooling system has been improved with increasing the mass flow rate of cooling air. The analysis model developed in this study can be widly used to find out an optimal battery cooling system in the future work.