Applied Mechanics and Materials Vols. 204-208

Abstract: Radiant floor cooling is a new energy saving air conditioning. In recent years, radiant floor cooling effect and its thermal comfort are still in the exploratory period in China. The body's comfort evaluation methods are briefly described in this paper. The indoor temperature and wall temperature of the building envelope determination method is analyzed. Nanhui Art Hall is used as object of study in this paper. Combined with the radiant floor cooling experiments, and using fanger formula calculation, the thermal comfort is calculated. Proper analysis of the results is in two aspects: the clothing thermal resistance and indoor air humidity. With the floor surface temperature below 21.56 °C, and air humidity 55% to 65%, it can meet the requirement of thermal comfort. The result will provide a helpful reference to energy-saving technologies and energy-saving equipment.

Abstract: Separation-of-variables method is one of the analytical solution methods to solve unsteady state heat conduction problems. But unsteady state conduction with heat source is an inhomogeneous problem. It can not be solved by separation-of-variables method directly. The combination of variables division method and separation-of-variables method was applied in this paper to deal with heat conduction with heat source in an infinite plate wall. The problem was divided to a steady state and inhomogeneous heat conduction problem, and an unsteady state and homogeneous heat conduction problem by variables division method. The steady state and inhomogeneous problem can be integrated directly. The unsteady state and homogeneous problem can be transformed to the problem that can be solved by separation-of-variables method directly through variable substitution. The unsteady state temperature field in the infinite plate wall was then obtained.

Abstract: When exterior wall adopts solar chimney thermal channel, natural ventilation comes into being in the thermal channel, which plays the role of reducing the heat indoor. In this article, we use FLUENT to explore the heat transfer and flow quality of the solar chimney thermal channel in Changsha area in the summer. The research mainly studies how different thermal channel widths, inlet and outlet vent heighst and solar radiation intensities can impact on ventilation effect and further concludes the rules of thermal channel flow field and ventilation rate changing of the solar chimney.

Abstract: With the growth of population and improvement of people’s life quality in our country ,the grain storage requirements are also gradually improving.This paper introduces the development of granary in different times in China,analyzed the advantages and disadvantages of the way of the grain storage and ventilation mode briefly,then introduce the current situation and prospects of the domestic low temperature grain storage.

Abstract: Appling urban untreated sewage as a cool and heat source of the heat pump air conditioning system is considered to be an effective way to develop urban sewage resource and a critical technique to serve the building energy system.Applications of technical difficulties are to solve the jam on sewage dirt to tube of heat exchanger and pipes. The multi-filter surface backwash technology is used to separate the suspended solids from the sewage and clean the dirt on the grille. By describing the filtration technique in the sewage source heat pump system to introduce the principle of operation and control process of the multi-filter surface backwash technology. By using in commercialese, the technology is proved to be feasible and reliability. These methods could serve as a reference for designing and application untreated sewage source heat pump systems.

Abstract: Roofs and walls are the main media for heat transfer for typical Malaysian buildings. In order to estimate the duration of uncomfortable periods, the environmental temperature of a building was determined over a period of time. A study of heat flux through a naturally ventilated was conducted by simulation. This study focused on heat transfer through the roof, ceiling and vertical walls. A Thermal Analysis Software was used for the modeling and analyses. A virtual test building model dimension 4m x 4m x 3m was created using conventional construction parameters for roof, ceiling, windows, door, walls and floor which meet the minimum requirement in Malaysian Standards. The results show that heat rate flux mostly peak at east wall before 12:00 hrs and west wall after 12:00 hrs. The heat rate flux through the roof is higher than that through the ceiling during daytime but lower at night as roof was the surface of most exposed to solar radiation. The proportion of heat through roof was 87% by radiation, 11% by convection and 2% by conduction. 97% of heat was transferred by radiation and 3% by conduction for ceiling and heat through wall was 88% by radiation, 8% by convection and 4% by conduction respectively.

Abstract: A new triangular Williams element with generalized degrees of freedom (GDOFs) was proposed for analysis of stress intensity factor (SIF) of mode II crack. The singular region around the crack tip was evenly divided into a series of triangular elements, which could be approximated by the improved Williams series. On the basis of the principle, the displacement of local field must be compatible with that of the global one, so that the SIF at the crack tip can be directly evaluated by one of the undetermined constants of the Williams series. Three important parameters for the triangular Williams element, including the radial scale factor, the number of subelements and the terms of the Williams series, were discussed in detail. Numerical example shows that the triangular Williams elements with GDOFs can directly calculate the mode II SIF with high accuracy and efficiency.

Abstract: Cement hydration heat temperature of the concrete could result thermal stress. Which is an important reason for the concrete structure’ cracks. The cracks could reduce the structure’ durability and structural stability. A spatial finite element model analysis on a mass concrete foundation board of a project was established using large-scale finite element analysis software. Temperature stress finite element analysis was carried on model. Numerical simulation analyzed the hydration heat of mass concrete construction phase and calculated the mass concrete’ temperature and stress distribution. Results of numerical simulation of crack control had certain guiding significance to mass concrete construction.

Abstract: It is necessary to test dynamics parameters of foundations at construction ground of large-size dynamic machine base. This paper elaborate the test technology and data processing methods on the basis of the block forced vibration test with engineering example, and test results are analyzed and discussed.

Abstract: This paper deals with the traditional stress concentration problems based on the eigenfunction expansion approach. Due to the completeness property of the eigenfunction space obtained by the previous researches, the solution of an arbitrary problem can be expressed by their linear combination. Thus the original problem is transformed into finding the combination of these eigenfuctions satisfying boundary conditions. By applying adjoint symplectic relationships of the ortho-normalization, the combination can be obtained numerically. Numerical results in tensional problems show that stress concentration appears when one of the ends of the solid is clamped. The concentration is seriously confined near the boundary of the fixed, and decrease rapidly with the distance of the boundarys.