Applied Mechanics and Materials Vols. 170-173

Abstract: In the ground source heat pump (GSHP) system, the temperature around the borehole exchangers (BHEs) would continue to spread further because of the heat accumulation, in addition the groundwater advection would have an important impact on the thermal dispersion. In order to have more accurate spacing between holes for design, the definition of temperature plume distance is proposed, based on the steady-state model with groundwater advection in porous media, the approximate analytical expression of temperature plume distance was obtained, the factors affecting the temperature plume distance was analyzed by comparing to infinite line source (ILS) model.

Abstract: In this paper, the operating conditions of air-conditioning systems in Terminal building of Guilin LiangJiang International Airport were tested and analysed. This paper mainly analyzes the influence of chilled water temperature on water chiller performance and derives the relationship of COP of water chiller and chilled water temperature difference between inlet and outlet , and provides reference for operation mode’s optimization of the air-conditioning system and energy consumption reduction of the whole building.

Abstract: The temperature fields of steel tube filled concrete columns are analyzed by a nonlinear FEM model in the paper. The theoretical results are validated by relative test results, and a good agreement is obtained. Using the theoretical models, the influencing laws of temperature rising time; section perimeter; steel reinforcement ratio and sectional core area ratio on temperature field of STRC subjected to 3-side fire are further discussed. By above parametric analysis, it has been found that the effects of heating time, sectional dimension and sectional core area ratio on temperature field are significant, but steel ratio has very little effect on temperature both of steel tube and of section surface.

Abstract: Hydro-junction of Hada Mountain is in the frozen soil region, solving antifreeze to eliminate structure deformation failure is the primary problem. By experimental proof, using channel insulating and anti-freezing can effectively solve the problem of soil frost heaving, and play a very important role in improving engineering quality and prolonging engineering life. In this paper, through a freezing period of field observations, according to the site laying insulation board of different thickness has greatly effect on reducing channel frost heave and improving channel temperature, Increased substrate temperature and provide reasonable design scheme and reasonable thickness of polystyrene board for other channels in this region, thus in greatly degree can improve channel frost heave phenomenon.

Abstract: This paper introduced a design and implementation of heat exchange station control system based on PLC and industrial configuration software, including the control scheme and principle, hardware selection and software design, etc. The circulating pumps and replenishing pumps in the system can all be driven automatically by PLC and inverter. Main process parameters e.g. steam pressure and measurement temperature can all be shown on the industrial PC running configuration software, and instructions could be sent by the engineer and operator on-the-spot via the Human Machine Interface as well. The automatic pressures adjustment of steam supply of the heater by advanced PID algorithm has been realized finally. It is verified that the system is highly reliable and stable, and it greatly enhances the level of automation and pressure control accuracy of the heat exchange station and meets all the equipments running demands well.

Abstract: According to the phenomenon of insufficient utilization of the geothermal water in the heat supply system of a campus in Tianjin, an optimization retrofit scheme with cascade utilization of the geothermal water is introduced in this paper. The energy efficiency of the heat supply system was improved after the retrofit: 30% of the electricity consumption was saved and an extra building area of 120,000 m2 could also be served by the same heat supply system.

Abstract: In situ measurements on two power plants designed air-cooled condenser structure were described in this paper. Operating condition was divided into three types to test the structure system, and then obtaining the data of time-domain waveform and spectrum analysis in each condition. Cycle, frequency and vibration mode of the structure system were obtained by analyzing the data. Meanwhile, the structure was theoretically calculated using finite element program, gaining the cycle, frequency and vibration mode of the structure system. It was concluded that basic vibration mode of the structure system was space torsional vibration by comparison between theoretical values and measured values.

Abstract: Four kinds of insulation roofs of naturally ventilated rooms in Chengdu(P.R.C) were tested to evaluate the thermal performance in summer. The thermal characteristics of roofs with different construction were compared by regression analysis. The experimental results showed a strong negative correlation between the highest outdoor air temperature and the largest temperature increment. As the highest outdoor air over 29.1°C, the light green ventilated roof has the best insulation performance. Under "sunny - rain" climatic conditions in summer, the heat flux through the extruded polystyrene insulation roof was always toward outside, which is not good for cooling the structural roof at night. The heat flux of inner surface of concrete slab ventilated roof was the most sensitive with mean solar radiation, and it has the worst performance for attenuating fluctuations of solar air temperature of outdoors.

Abstract: Designed a new type of plate heat exchanger-dimpled plate heat exchanger, then conducted a three-dimensional numerical simulation on flow, heat transfer and resistance characteristics of 15 kinds of different sizes dimpled plate heat exchangers by Fluent software，obtains the impact of the dimples geometric parameters such as dimple diameter, dimple spacing, dimple height on the heat transfer and flow characteristics. The results show that in different Reynolds number, dimple diameter, dimple spacing and dimple height on the effect of the dimple plate heat transfer efficiency is quite similar, and the impact becomes increasingly evident with the Reynolds numbers increasing. The combined effect of plate heat exchanger is best when dimple diameter, dimple spacing, dimple height are separately 12mm, 21mm, 4mm in the 15 kinds of different combination dimpled plates.

Abstract: Hybrid ventilation has significant advantages in building energy-saving. We discussed the potential and influencing factors of the rational use of building hybrid ventilation systems in three typical cities, located in three different climate regions of China. We used the Adapted Comfort Standard (ACS) model and Energyplus software to analyze the hybrid ventilation efficiency. This method combines the advantages of Degree-Hours Method and Heat Balance Method, and also takes into account the wind-driven and buoyancy-driven models. Results shows that the natural ventilation potential (NVP) utilization hours of high thermal insulation buildings with temperature control ventilation can be up to 5080h in Beijing, 6195h in Nanjing and 6726h in Guangzhou, accounting for 58.0%, 70.7% and 76.8% of the full year respectively. It means that the rational use of hybrid ventilation and ventilation mode can significantly reduce building energy consumption in summer.