Applied Mechanics and Materials Vols. 170-173

Abstract: Under mechanical extraction in a fire room, a quasi-steady state will be eventually formed based on a two-layer zone concept. Heat loss through solid boundaries is a key factor which determines the temperature of smoke layer at quasi-steady state and will be discussed in this paper. A simplified model on heat loss of smoke layer is proposed. Calculation is performed and results are plotted. It is indicated that the ratio of heat loss through solid boundaries to the convective part of fire power, χ, varies under different exhaust rates and heat release rates of the fire. Heat loss of smoke layer through solid boundaries should be considered and calculated using heat transfer theory, instead of taking as a constant part of convective heat release rates of the fire.

Abstract: To evaluate the effect of a converging injector geometry, volumetric flow rate and gallant content on the pressure drop, the velocity and viscosity fields, the governing equations of the steady, incompressible, isothermal, laminar flow of a Power-Law, shear-thinning gel propellant in a converging injector were formulated, discretized and solved. A SIMPLEC numerical algorithm was applied for the solution of the flow field. The results indicate that the mean apparent viscosity decreases with increasing the volumetric flow rate and increasing the gallant content results in an increase in the viscosity. The results indicate also that the convergence angle can produce additional decrease in the mean apparent viscosity of the fluid. The mean apparent viscosity decreases significantly with increasing the convergence angle of the injector, and its value is limited by the Newtonian viscosity η_∞. The effect of the convergence angle on the mean apparent viscosity is more significant than the effect of the volumetric flow rate and the gallant content on the mean apparent viscosity. Additional decreasing the viscosity results in increasing the pressure drop with increasing convergence angle. It is important to injector design that the viscosity decreasing and the pressure drop increasing are took into account together.

Abstract: In order to achieve the target of controlling SO₂ emissions in fumes in a short period of time in China, it is necessary to develop a SO₂ on-line monitoring system (CEMS) that is suitable for China. To monitor total emissions of SO₂ in fumes, the concentration of SO₂ in the fumes and fumes flow rate must be monitored simultaneously. To monitor fumes flow rate, first we must monitor its average flow velocity, this is a major technical problem need to solve in the SO₂ CEMS. By means of study on velocity field constant in flue, An advanced method for monitoring average flow velocity of fume by mean of velocity field constant is presented, meanwhile an innovative device has been developed to detect velocity field constants automatically, which has resolved the technical difficulty in automated monitoring of fume average velocity in the flue. Through experiment and testing, the monitoring method researched is correct, structure of detecting device is reasonable, its monitoring results are stable and reliable.

Abstract: The heat output for borehole heat exchangers due to the variation of U-tube diameter was theoretically analyzed using the steady heat conduction model of a hollow cylinder. In the present model, except of the U-tube diameter, the other influencing factors on the heat output, such as the heat transfer coefficient inside U-tube, tube thickness and thermal conductivity, have been taken into account.

Abstract: The courtyard sunspace was built up according to courtyard characteristics of rural residence in Qingdao, A mathematical model was established for courtyard sunspace solar house based on its heat transfer mechanism, and the relationships of sunspace ventilation opening area, courtyard sunspace temperature and indoor ventilation quantity was analyzed. The results showed that temperature of courtyard sunspace will decease with increasing ventilation opening area of courtyard sunspace and lead to decrease the indoor ventilation quantity, which will provide theoretical basis for ventilation opening design of courtyard sunspace.

Abstract: “Hanging and Top-Down” (HTD) Method of ventilation shaft construction Technology will be described in this paper. Using this method, the shield pass a more shallow ventilation shaft pit quickly just close beneath it, the tuyeres between the tunnel structure and the base slab of ventilation shaft pit are constructed later using a technology similar to “top-down method”, and the tuyeres hang at the base slab of the pit, no dewatering adopted during the construction. This paper will also address efforts at solving the problems the technology encountered, especially the method to control the deformation of tunnel structure.

Abstract: Experimental research on the characteristics of co-combustion coal and combustible gas has been carried out. The influence of nozzle position and combustible gas reburning ratio on N₂O and NO removal rate were carried out at CFB experimental platform. It is found that N₂O removal rate achieved a maximum value when the reburning gas was injected into furnace from nozzle C with a height-diameter ratio of 8.3, and the NO removal rate is about 50%; When the combustible gas were injected into furnace from nozzle C, the N₂O removal rate kept increasing with the increase of reburning ratio (R_m), which can reach 99% when the Rm value is 10.5%. In addition, the NO removal rate is increasd after the first reduction with the increase of R_m, when the rate is about 39% with Rm is 10.5%.

Abstract: Abstract. The separate condensing Linder refrigerator by using mixed-refrigerant with pre-cooling cycle in 120K temperature rang is proposed and the experimental device is established, then the corresponding experiments are conducted. The results show that the best ratio of ternary refrigerants(R23/R14/R740) is 0.63:0.28:0.09, the refrigerating temperature of the unimproved system without heat loads is 150 K, but the refrigerating temperature of the segregation Linder refrigerator system without heat loads is 120 K.

Abstract: The author analyzed the natural ventilation effective pressure differential and Pressure Differences Pascal Hours (PDPH) according to the meteorological parameters in the five region of Shandong province, for example, Weifang, Chengshantou, Longkou, Yanzhou and Jinan. Through a simulation for one typical building, the hours of effective ventilation in the room of Different location in this building and natural ventilation potential data is received

Abstract: In order to solve the ‘condensation heat excess’ problem for protective underground engineering, a new condensation heat processing schema was proposed, which is based on the theoretical analysis results that the condensation heat should be transferred to the exotic environment. The main idea of the proposal is utilizing exhaust air of the ventilation system and applying evaporative heat transferring mode.