Advanced Materials Research Vols. 354-355

Abstract: In some circumstances, huge mass, if not cushioned, may pull the piston to a halt at rod side or head side at ease with a tremendous velocity causing huge impact. As a result of this issue, the boom cylinder of hydraulic excavator provides cushioning apparatus at the rod side stroke end. This paper discusses and analyses the cushioning apparatus structure of boom cylinder, and then proposes a numerical simulation model with SimulationX. It is known to us that many dynamic parameters of boom cylinder vary as mechanical structure or motion of excavator attachment changes. Thus in order to study the relationship between kinetic parameters and cushioning capability of boom cylinder, an excavator attachment model is built next. The last part of this paper is devoted to the obtained simulation results.

Abstract: The flow and heat transfer characteristics of a micro heat exchanger structure are studied with the method of contrasting experiment and Fluent numerical simulation. Considering the micro heat exchanger to meet the work requirements of conditions, there is some optimization of the structure redundancy. The optimal model of micro heat exchanger is obtained by the numerical simulation and comparative analysis on seven different kinds of micro heat exchangers.

Abstract: Coaxial nozzles are an integral part of many engineering systems where mixing of different fluid streams is required. Single noncircular nozzles have been shown to have better mixing characteristics than their axisymmetric counterparts. Therefore, a combination of such nozzles into coaxial configurations is promising. The aim of the present study is to quantitatively determine the effects of the geometry of the primary supersonic jet on the mixing characteristics with the secondary high speed subsonic jet. Measurements of pressure profiles at several positions along central axis of jets using identical facilities and nominally identical experimental conditions were done. The mixing is dominated by the vortex structures that are present in the inner shear layers. The interaction of the vortex structures govern the growth, and entrainment, and mixing of the jet. Also, the experimental results show that the radial and centerline pressure profiles through various coaxial jets has good correlation with the CFD simulation.

Abstract: Particles concentration distribution in a stirred tank with pitched blade turbine was investigated using computational fluid dynamics. The effect of the pumping mode on the turbulent flow and particles concentration distribution was studied. The turbulent solid-liquid flow in a stirred tank was simulated using a two-fluid model with standard k-ε turbulence model. The multiple reference frames approach was used to simulate impeller rotation. Results show that different pumping modes create different flow field which decide the characteristics of the mixing quality. A further detailed discussion about particles mixing at the bottom of the stirred tank was made. The computational model and the predicted results discussed here would be useful for understanding the solid-liquid mixing process.

Abstract: Abstract: The experiments were conducted by planting in the field of 2 year-old Mongolian Pine (Pinus sylvstris var. mongolica) seedlings processed with Pt mycorrhizal agents, ABT rooting powder, HRC water-absorbing agent and GRR plant development and growth regulator. The results were as follows: (1) Pt₃ and ABT had significantly increased survival rates of seedlings, which were 29.3%, 23.6% and 9.4% higher than that of controlled seedlings, respectively.; (2) Pt₃ and ABT had enhanced the growth of the fine root(<2mm), which were 34.72 and 15.18 cm longer than that of controlled seedlings; the regression analysis had showed that fine roots quantity was positively related to seedling survival rate; (3) The growth indexes of the average individuals with Pt₃, ABT and HRC were higher than those of untreated seedlings; (4) Pt₃ and ABT also effectively promoted the absorption of main nutrients such as N, P, and K in the needle of seedling.

Abstract: The biomass carbons were studied with ZnCl₂ as activating agent, methylene blue as index and its Hg adsorption experiment was conducted. The adsorption of soybean stem activated carbon for methylene blue was 149.84μg/g, and its adsorption capacity to Hg in flue gas in 4 hours was 14.57μg and penetration rate was 5.30% at the conditions of 600°C activation temperature, 90 min activation time and ZnCl₂ concentration 50%, and the mechanism was analyzed.

Abstract: in order to study and analysis on pressure distribution of pipeline system under the conditions of different power, to obtain the mutual influence degree between users. Through multi-storey residential pressure change exhaust system measured under the condition of three pressure changed board, the experimental results are compared and analyzed. The result of this paper obtains pressure of the mains and branch and branch speeds in different conditions. In six floors of 400 * 250 pressure changed type exhaust pipe system, no matter exhaust fan’s volume is high-end or low-end in any conditions can satisfy the exhaust requirements. Pipe internal pressure showed low - high – low.

Abstract: In order to obtain the thermal comfort work environment, the distribution of temperature and airflow velocity in typical computer room of school building is discussed with different supply air angles and velocities of incidence by CFD model. The calculated temperature after cooling in the room has a good agreement with the measured value. Furthermore, the distribution of temperature and airflow is uniform and the environment is comfort for working with supply air angles and velocity of incidence 45° and 60° and supply air velocity of incidence 1m/s comparing with that of other parameters. Additionally, the change of temperature becomes slow down with the increment of time and the air-conditioning has less influence on the change of temperature after about 900s with supply air angle and velocity of incidence 45°and 1m/s, respectively. The research is of great significance both in theory and practice to design air conditioning systems and evaluate the thermal comfort conditions.

Abstract: The design of heating systems with groundwater source heat pumps (GWHP) is very important for reducing their power consumption. For better design, reasonable analysis of the systems is necessary. In this paper, a dynamic exergy and exergetic cost analysis of a heating system with GWHP is performed in a whole heating season by the use of structural theory of thermoeconomics and the software of TRNSYS. The relative exergy destruction of every component and the exergetic cost of the final product of the system are obtained. The results show that the heat pump has the largest relative exergy destruction under all the working conditions. The terminal unit component has the second largest relative exergy destruction at conditions above 10% load. However, at 10% load, well water transportation component has the second largest relative exergy destruction. The unit exergetic cost of the system final product during the whole heating season is 8.51W/W, similar to the result at 75% load.

Abstract: Adopting the k-ε standard model, the CFD simulation software to simulate the indoor kitchen and toilet different row of indoor air volume air distribution in natural ventilated circumstance, by comparison results show that different row of indoor air volume changes in the rate of secondary pollution rate, and then to provide the change rule of indoor air quality protection reference basis.