Applied Mechanics and Materials Vols. 548-549

Abstract: The paper mainly studies the influence rules of temperature (10°C~60°C) and curing time on shear strength indexes of cohesive soil, such as cohesion and internal friction angle, which are very significant in civil engineering works as the temperature of the earth’s surface increases. Such influence plays an even more important role in the design of the ground source heat pump and the geological disposal of high-level radioactive wastes. In this paper, the triaxial unconsolidated-undrained tests on unsaturated cohesive soil samples have recently been performed. And the testing results show that the shear strength increase as temperature and curing time increase, which is a phenomenon that needs further researches. The cementation get reinforced and the change of the content of closed air caused by the temperature curing may be the key factors.

Abstract: As global energy crisis is growing, energy-saving in architecture becomes more and more important. In addition, residential lighting especially living room lighting is an important part of energy consumption. In order to create green building, this paper analyzes energy-saving status based on joint investigations across China, Japan and Korea. It has been also compared the differences about energy-saving awareness and the selections of lighting equipments. The investigation results about residential lighting energy situation are reference to make proposals on lighting energy efficiency and quality improvement.

Abstract: The paper deals with the use of MATLAB and COMSOL Multiphysics environments for solution of optimization problem regarding underground thermal processes occurring at the old mining dumps affected by subsurface endogenous fires. It gives the description of measurement system and physical setup of the experimental borehole used to provide the real measured data for the model with the aim of its verification. The optimization problem is defined and solved by proposed computational technique that uses both MATLAB and COMSOL Multiphysics with the LiveLink tool that integrates these environments. Results of the optimization help to evaluate the total or relative heat power of the mass within mining dump.

Abstract: This paper summarizes the two methods which are experimental research and numerical simulation to thermal environment of the tunnel. Then the latest developments of the thermal environment research at home and overseas are introduced. At last a simplified model of thermal environment of underground tunnel is established. Through CFD software, the radial temperature distribution of tunnel surrounding rock and the axial temperature distribution of air at winter and summer conditions are obtained which provide basis for further research on thermal environment of underground tunnel.

Abstract: Different indoor thermal environment was affected by the different supply air parameters. In this paper, the indoor temperature field and PMV value in the conditions of different supply air angles were studied to explore the influence of indoor thermal environment and human thermal comfort affected by the varied supply air angles. The experimental results showed that the average temperature of indoor air and the temperature gradient of personnel main activity area increased with increasing the supply air angel. In contrast, a relatively comfortable indoor thermal environment could be formed with the supply air angel between 0°to 15°.

Abstract: Natural conditions are conducive to the application of surface water source heat pump technology in Chongqing, and the application of open-loop surface water source heat pump system is more common than the close-loop style. Introduces the ultimate principle of the Water percolation and Water-intake directly method, and corresponding with the actual case, makes comparison and analysis to the main factors considered in the selection of water-intake methods.

Abstract: According to the existing problems of conventional air conditioning system, this paper presents a new form air-conditioning based on the principle of gravity cycle, analyze its merits and drawbacks and application area, to provide a theoretical basis for the popularization and application of the new air conditioning form.

Abstract: In order to analyze the influence of groundwater flow on ground heat exchangers with different arrangements, with a project in Nanjing the access temperature field in the multi-borehole field was simulated after the ground source heat pump system had been performed for a year. Simulation results show that the access temperature is higher in the ground surrounding the borehole than the center of the corresponding borehole, thus forming a thermal barrier surrounding the borehole. Groundwater flow helps relieve temperature imbalance owing to the imbalance of heating and cooling load. The performance of the ground heat exchangers is better in staggered arrangement than in aligned arrangement. In the borehole field, the boreholes upstream have thermal interference on those downstream. And the extent of thermal interference depends on the direction of the groundwater flow when the locations of the boreholes are fixed in the borehole field.

Abstract: Thermal stratification affects the flow in and above urban street canyons. Such thermal effect is often not noticed, and can lead to pessimistic or optimistic results of the air quality in urban street canyons under calm conditions and low wind speeds. A three-dimensional CFD model is applied to simulate the flow patterns and particle concentrations in a street canyon under different aspect ratios and ground thermal conditions. The model is validated by the experimental data found in the literature. The simulation results are used to evaluate the flow and pollutant dispersion properties in the canyon. The results show that the ground thermal conditions can significantly affect the ventilation performance of the street canyon, which improves with the increased temperature difference (ΔT) between the ambient air and the ground of the canyon. The increased ΔT enhances the buoyancy induced secondary flow in the street canyon and hence reduce the particle concentrations in the canyon, with this influence more pronounced for small street widths.

Abstract: Hydrate formation has long been a challenge for flow assurance in deepwater natural gas pipelines. Hydrates are formed when natural gas is brought into contact with water usually at low temperature and high pressure in deepwater pipelines. The pressure is relatively high in deepwater pipelines, so it is entirely possible to meet the hydrate formation conditions and pose a significant operational and security challenge. This study provides a means to ascertain the thermodynamic properties for hydrate formation in a deepwater gas pipeline. The thermodynamic properties are to be assumed between the similarity of the hydrate formation and the isothermal adsorption in a deepwater pipeline. The study aims to develop a correlation for calculating the hydrate formation pressure, temperature and fugacity of a gas mixture. The correlation is based on the gas hydrate formation temperature and pressure with and without inhibitors. This study also provides a hydrate prediction phenomena associated with gas condensation in deepwater pipelines and it will improve the ability to predict the thermodynamic properties of hydrate formation.