Applied Mechanics and Materials Vols. 170-173

Abstract: Hydrodynamic for 2D vibrated fluidized bed was studied with large particle glass beads of average diameters are less than 1.5mm.The effect of the vibration strength, the static bed height and the particle diameter on the critical fluidization velocity was analyzed. The results show that the critical fluidization velocity decreases with the increase of the vibration strength, and increases with increases of the static bed height and particle diameter. The effect of vibration on critical fluidization velocity was more significant than decrease the bed height and particle diameter. The empirical correlation equations to predict the critical fluidization velocity was established, and the results of the prediction were compared with the experimental data, the error is in range of ±10%. The results can provide important meaning on theory and instructing practice for developing the new drying technology with high drying efficiency and low dissipation of energy.

Abstract: large eddy simulation cooperated with a physical fractional-step method is applied to simulate steady flow around a nested type fixed-cone valve; and the equations are solved with the finite volume method. The free fluid surface is simulated by the VOF method. The pressure contours and vorticity magnitude are obtained. The modeling results conform to physical law, and show that the large eddy simulation theory has powerful capacity in simulation of microstructures of turbulent flows, and the function of the nested type fixed-cone valve for energy dissipating is good.

Abstract: The ground settlement caused by high-rise buildings is prominent increasingly with the rapid development of city construction, and will have negative influence on the surrounding gas pipelines. In this paper, an on-site monitoring system for settlement and stress-strain of buried gas pipeline is established, located in the neighboring area of Shanghai Center Tower, which is being built and will be the tallest building in china. The continuous online, real-time monitoring of stress changes and pipeline settlement can be realized. With the system of GPRS automatically data acquisition and wireless remote transmissions are achieved. Field test testify the effectiveness of the system, also shows that significant settlement and strain exist in the test pipe, and long-time monitoring and analysis is needed

Abstract: The paper builds up the model for exergy analysis of vapor compression refrigeration. According to the exergy analysis, it appears exergy loss degree of the main units in the system, and points out the way of reducing exergy loss and the approach utilizing energy rationally, and proceeds with exergy loss compare with aiming at that if condenser in surplus heat recycling. Conclusion is that adopting surplus heat recycling can reduce exergy loss. Furthermore, it analyzes exergy loss to a actual refrigeration aiming at temperature regulation, and provides the theory reference for improvement and optimization of the system.

Abstract: An air-air energy exchanger (AAEE) has been introduced in the literature as a novel energy recovery system that transfers heat and moisture between the ventilation and exhaust air. In this paper, the application of an AAEE in a HVAC system is investigated. The paper discusses the dependency of AAEE performance on ventilation air and indoor and outdoor air conditions, it describes how to control the AAEE in different operating conditions (summer and winter). The suited meteorological conditions of the AAEE in buildings are given. Based on the humidity and temperature data of the typical meteorological year in Xiamen, the temperature distribution statistics throughout the year is studied and the air enthalpy difference is calculated. Combining with the demand of the indoor air conditioning parameters, the applicable hours of different types of AAEE, such as total heat and sensible heat, in Xiamen are analyzed. It is shown that the lower we intend to get the temperature and relative humidity, the more space there will be for the AAEE to work in summer. In winter, for the sensible heat AAEE, the higher indoor temperature we design, the more hours it works, the greater space we will have for heat recovery. But for the total heat AAEE, it will be used longer as the indoor temperature and relative humidity are designed higher. The study results show that the AAEE can be energy-saving and reduce indoor air pollution of modern buildings, improve indoor work and living environment. The result can provide basic principle and referenced data for product improvement and air-conditioning system design.

Abstract: Method of CFD was adopted to carry out two-dimensional numerical simulations for internal natural ventilation process of a standard triple-span workshop in iron and steel enterprises with3 different layouts of heat resources. Flow states and relevant parameters of air-fluid in the workshop were obtained to come up with theoretical basis for design, optimization and process layout of natural ventilation in workshops.

Abstract: Ground coupled heat pump has become an attractively alternative way to cool and heat buildings in China, however, in practice their operation and effect especially on the performance of heat exchanger are unsatisfied. In this paper, the influence of buried tube depth and operational mode on heat exchange performance were studied by experiment. The experimental results showed that intermittent operation mode will help to improve energy efficiency of buried tube,and improve the host operating efficiency. In the operation, buried tube will produce inevitably cold and heat accumulation effect in surronding rock mass, and result in water temperature of buried tube oulet rising (summer) or decreasing(winter), cooling temperature of the condenser (summer) increasing, evaporation temperature of evaporator decreasing (winter), then the operating efficiency of host machine in the actual operation would be decreased. It is suggested that ground source heat pump system with auxiliary cold/hot equipment should be considered in practice.

Abstract: Cascade Rankine power cycle is suitable for cold recovery in a CCHP system which uses LNG as the primary energy. It has the advantages of low operating pressure and high energy efficiency. Exergy analysis of a typical cascade ethylene-propane Rankine power cycle is conducted. The results show that the exergy losses mainly occur in the low temperature part of the cycle. The exergy loss in the LNG-ethylene heat exchanger could reach about 46% of the total exergy loss. Therefore, the reduction of the exergy losses in the low temperature is important for the improvement of the performance of cascade power cycle.

Abstract: The subway is the major means of transportation in Beijing, and it also takes huge energy consumption. Now the consumption of a subway station is 9500 kWh every day, and the proportion of the air-conditioning system energy dissipation is about 64%, in which, a big part of that can be saved down to save and make full use of the energy. The key to the air-conditioning system energy saving is to put forward reasonable energy-saving schemes and feasible method. In this paper, with a subway station in Beijing as a test location，the measurement and data analysis are carried out, and the schemes put forward for energy conservation and emission reduction in subway air- conditioning system.

Abstract: It introduces solar water heating system briefly, states the feasibility and necessity of the application of this system in severe cold region, analyzes the advantages of flat plate solar water heating system and people’s misunderstandings and finally indicates the applicability and prospects of this system in severe cold region.