Advanced Materials Research Vols. 712-715

Abstract: The relationship between exergy efficiency and output acoustic power of the thermoacoustic engine microcycle model which only was accounted for the heat resistance had been analyzed using finite time thermodynamics.And through the new objective function,we obtain the optimization that not only obtain high exergy efficiency but also high output acoustic power at the same time.Optimized imperfection that we only pursue the high exergy efficiency, we obtain low output acoustic power and vice versa.We approve this conclusion by numerical calculation.The results that we obtained will be useful to optimal the design of a actual thermoacoustic engine.

Abstract: Through to investigation on present situation of the Changzhou Changrui Hotel air conditioning system energy consumption, by analysis the energy consumption, the power consumption of hotel central air-conditioning system charge 58% of the total electric, accounted for a large proportion. So we should take the necessary measures to reduce the expenses of air conditioning system energy consumption. According to the analysis of data on the survey, we put forward some particular energy-saving measures of central air-conditioning system of the hotel, including strengthening the building envelope insulation, energy saving technology of doors and windows, measures of roof energy saving, setting reasonable indoor temperature, adopting frequency control air-conditioning, reuse waste heat of the central air-conditioning, using the condensation water of central air conditioning to make-up water and reducing temperature of cooling tower , and drying the fresh air independently.

Abstract: The author studies the factors on influencing energy consumption of three kinds of common forms of external window of the winter heating and summer cooling, according to the characteristics and influencing factors of living building external window of colding and heat load in severe cold areas, using the simulation software DeST-h to a certain residential building in Changchun City as an example. It analyses the effect of energy saving characteristics of different forms of windows and the influence on building energy consumption. It provides technical reference on rational design of the external window.

Abstract: A nodal analysis method for thermodynamic analysis of Stirling engine is modified based on the check of mechanical loss and the temperature of the heater and cooler. A computational modeling for simulating the process of oscillating flow and heat transfer occurring in the P-40 four-cylinder double-acting Stirling engine has been developed, and the changing effects of different parameters such as the internal pressure, temperature, velocity, power and efficiency are obtained. Numerical simulation results show that they coincide with the testing data given by NASA. The influence of speed, working fluid and average pressure on the engine output performance is analyzed by the modified nodal analysis method. This method is a useful tool for the optimal design and operating characteristic analysis of Stirling engine.

Abstract: The overall numerical analysis of liquid bridge for high Pr number fluid and flow field of ambient air under the zero-gravity environment was carried out in the present paper. The paper used level set method of mass conservation to capture two phase interfaces. Not only the free surface deformation was considered, but also the effect of ambient gas was taken into account. Simultaneously, results of stream function in liquid bridge and ambient gas-phase were given.

Abstract: In order to improve the comprehensive mechanical properties of the steel, the heat treatment software COSMAP is used to simulate the rolling and controlled cooling of I-beam. The numerical simulation shows that: when the cooling rate is controlled at 10 °C/s around, the mechanical properties of controlled cooling can be obviously improved. The strength and hardness can be improved on the condition of ductility and toughness ensured, while the amount of residual austenite can be reduced significantly, which provide a theoretical basis for further optimization of the heat treatment process.

Abstract: A numerical model has been developed to investigate temperature field of high prandtl number liquid bridge under zero-gravity condition, and numerical simulations have been carried out. The Navier-Stokes equations coupled with the energy conservation equation on a staggered grid. In numerical calculations, we considered not only the free surface deformation but also the effects of ambient air. Overall numerical analysis of liquid bridge was carried out by level set method of mass conservation to capture two phase interfaces. Simultaneously, results of temperature field in liquid bridge and ambient gas-phase were given.

Abstract: The thermoacoustic conversion system is designed, while the position and structure parameter of stack are calculated and analysed. At the same time, the parameters of stack and the input working frequency which influence the system are researched by experiment. The results show that the center position of stack in the standing-wave tube and the length of stack have great influence on the system, and exists a best value in the same input power and frequency; Meanwhile, the pore diameter and wall thickness of stack are also exist the best values, the temperature difference at both ends of stack will be reduced if the value is too big or too small; The best working frequency of the system is migrated due to the stack, working fluid and so on.

Abstract: Before the working speed of high-speed spindle system reaches the critical speed, violent vibration which directly affects the quality of the work piece has been already discovered. To precisely study the speed at which violent vibration happens and the modes of vibration, this paper provided an order vibration approach through studying the model analysis and order of spindle system. The nature frequencies of model analysis were verified and the order of spindle system was confirmed by speed ascend experiment. The result shows that the violent vibration is caused by the manufacturing error of outer ring race of bearing and the mode of vibration mainly located on the grinding wheel which greatly affects the accuracy of spindle system. It is useful for optimizing the structure and operation procedure of high-speed spindle system.

Abstract: With the Stochastic Minus method to get the vibration signal of bridge structure based on seismic excitation. Meanwhile, in order to verify the validity of the method, we make a computer simulation to a prestressed concrete continuous beam bridge. And we point out that the method is suitable to monitor the bridge structures based on environmental vibration.