Applied Mechanics and Materials Vols. 353-356

Abstract: Checking the global and local stability of cooling towers during construction is very important to construction safety and reasonable construction process. On the basis of existing researches and by combining the checking method of global and local stability of cooling towers in operation period given in the present design code, this paper presents a method with implementation steps to check the global and local stability of cooling towers during construction. The method is verified to be simple and effective by a cooling tower example. The example analysis indicates that the global stability of cooling towers decreases with the construction height and achieves the minimum when the topmost layer is just built, though it increases bit when all concrete layers reach the design strength. The local stability of cooling towers during construction is poor in the range of 1/5 to 3/5 tower height and should be paid great attention during construction.

Abstract: There is highly relevant between thermal comfort and air quality in indoor spaces. Temperature, wind speed, and other related conditions are crucial to workplace and living environment. The commercial software of Solidworks Flow Simulation is applied to conduct a three-dimensional office environment model in this paper. The numerical simulation according to flow field characteristic analyzes different air controlling in varied closed partition. Through the two convergence conditions, MRT and OT, get the air characteristics of the grid and to calculate the PMV and to predict the PPD using the software. Therefore, designers can acquire more adequate information of thermal comfort, wind speed and temperature in preliminary design stage via the efficient simulation process.

Abstract: The fire smoke flow prediction software developed successfully was applied to simulate a simple building. The effect of different wall structures on the fire smoke flow properties were compared under the condition of same thermal resistance of external wall. Heat absorption of wall has a cooling effect on indoor air in fire process. Wall with external insulation has the most significant cooling effect on indoor air, and that with internal insulation has the weakest. The effect of intermediate insulation is close to external insulation and that of bilateral insulation close to internal insulation. Room temperature and smoke concentration of internal insulation are both higher markedly than of external insulation. The effect of intermediate insulation is close to external insulation and bilateral insulation close to internal insulation. External insulation added to the closure helps to cool indoor air in the fire process. Intermediate insulation should be chosen to add to the inner wall when needed because of the uncertainty of fire location.

Abstract: in order to study the piston wind and its effect on the thermal environment and velocity field in island subway station platform with full-height non-enclosed screen doors, a number of field measurements were taken at the platform of century station of metro line 2 in Shenyang from Oct. 2012 to Mar. 2013. The test results show that the full-height non-enclosed screen doors enhances the heat transfer between the platform and the tunnel, the effect of piston wind increases the average temperature of platform by 0.7°C-1.4°C. Meanwhile, the full-height non-enclosed screen doors prevent the piston wind from entering into the platform effectively. The wind speed of the platform fluctuates between 0.25~0.52m/s when no train enters or leaves the platform, increasing slightly under the effect of the outdoor wind velocity. When one-way train goes into and out of the site, the maximum wind speed reaches up to 2.2m/s at the working area of platform. While, the wind speed of the stair section shows cyclical shocks between 1.2m/s ~ 1.7m/s with the amplitude attenuates gradually.The two-way train caused the the maximum wind speed up to 2m/s with the duration of 220s.

Abstract: The air ventilation rates defined in Standard STN EN 15 251:2007 present air change rate in which the objective benefit of proper selection of ventilation system and air distribution scheme is lost (erased) in relation to IAQ [1,2]. With help of sensory evaluation in research the total minimum ventilation rate was estimated. It was reason how to determine major boundary condition (air quantity = air ventilation rate) for minimizing of responsibility size of air quantity (quantitative component of ventilation) and maximize the impact of the choice of distribution scheme and the distribution element (qualitative component of ventilation) for transfer and distribution of pollutants in research. The total air ventilation rate for next experimental measurements was established as the intersection of three air ventilation rates according to research harmonogram. This air ventilation rate was necessary to supply to occupant to experimental classroom and also as input value to CFD simulations.

Abstract: A seamless prism light guide made of polymethyl methacrylate (PMMA) is introduced in this paper. The light-transporting efficiency and light-distributing character is analyzed. As comparative sample, the optical characters of an opalescent PMMA light guide are also introduced in this paper. Experiments show that the guide has high light-transporting efficiency that makes high illuminance at the end of the guide. The light-transporting efficiency of the seamless guide is nearly two times higher than that of the opalescent PMMA light guide.

Abstract: The terminal device (VAVBOX) is the key part in variable air volume (VAV) air conditioning system, by which we can adjust air output, compensate indoor load change, keep room temperature to be constant. The control effect of VAV system depends largely on the performance of terminal device and the coordination between terminal device and the whole system. In this paper, BAS - 3520 DDC produced by Advantech corporation is used to design VAV air conditioning pressure independent terminal controller. Experiments show that the terminal controller based on DDC can well satisfy the system control requirement, the transition time and overshoot of the indoor temperature achieve good improvement. At the same time , with Webaccess introduced, VAV BOX operation condition can be monitored by host computer, what makes the daily management of the VAV BOX more intelligent.

Abstract: Good indoor air quality is the basic requirement of people's production and life, so it becomes more and more important and urgent to improve the air quality of the anatomy laboratory. According to the specific characteristics of the anatomy laboratory, the paper simulates the distribution of the velocity field, the formaldehyde concentration field and the air age of five ventilation modes by using the standard k-ε two equation model. The research will get a more effective ventilation model by comparing the simulation results. Then the simulation parameters will be adjusted based on the experimental results, it shows that the measured results are correspondent with the re-simulated results, and the error is also within the acceptable range. It is further to verify that the simulation method is feasible, and the conclusions obtained on this basis are acceptable.

Abstract: For hot water heating direct return system, the common hydraulic calculation method in engineering design is constant temperature drop method,which is calculated from the farthest riser loop. Due to the limit of the minimum pipe size, the method is usually difficult to achieve the hydraulic balance for every riser loop, and it needs the utilization of valves to meet the need. In this paper, through a calculation example, it has explained that every riser loop is very easy to achieve hydraulic balance without the utilization of valves when the system is calculated from the nearest riser loop. Besides, the calculation order of this method has been given.

Abstract: Make an analysis and points out that the engineering conditions of variable speed working condition of water pump in line with the proportionality law are as follows: non-back-pressure system, all parallel pumps changing speed synchronously (including a single variable speed pump system) and fixed pipeline characteristic curve. Energy saving effect analysis of variable speed pumps should be based on the energy consumption comparison of the pump variable speed control to other flow control methods in conditions of achieving the same flow, but not to the design working condition.