Advanced Materials Research Vols. 354-355

Abstract: In order to make full use of small current grounding system transient information and to improve the accuracy of fault line selection, a method based on wavelet transformation was proposed. On the basis of wavelets transformation theory and its characteristics, a proper wavelet function was chosen up to take wavelet transform to collected fault data, and then to get the fault line according to the modulus maxima theory. The MATLAB simulation results show the effectiveness of the proposed techniques on improving the accuracy of fault line selection.

Abstract: Experimental research on resistance and heat transfer properties of corrugated plate air-cooled heat exchanger under the condition of variable air and hot water flow rates has been conducted. The pressure drop and convection heat transfer coefficient correlation expressions both the air side and hot water side are acquired, where the Reynolds number for air side ranges from 401 to 6602 and the Reynolds number for water side ranges from 2536 to 19301 are adaptable.

Abstract: This paper presents the effect of over-voltage damage on contamination surface of porcelain insulator due to impulse high voltage connects in series with high voltage alternating current (HVAC) which studied by using rotating wheel dip test. This method is artificially accelerated ageing at short period and mostly resemble real application of insulator. To evaluate this effect, the frequency of leakage current (LC) waveform has been analyzed by fast Fourier transform. The results of the experiment showed that effect of HVAC series with impulse excitation voltage created a LC like as transient state which it is highest amplitude peak values of LC flow on the specimen surface. The partial discharge on specimen surface suddenly occurs after excite by both excitation voltage at few number of cycles and increasing depends on number of cycles.

Abstract: Analyzed the iso-pressure approximate model used in laser propagation in gas medium and pointed out its disadvantage under complex border conditions. The weakly compressible fluid model was developed which was based on the Mach uniform method introduced by Peter Wesseling. Using the weakly compressible fluid model and scalar wave equation, a numerical study was carried out for the gas thermal effects on laser propagating in a closed tube full-filled with air. The far-field beam shape at different time were obtained and compared with the experiment ones. It is shown that the weakly compressible fluid model could be well adapted for problems with complex border conditions, acute than the compressible fluid model or the iso-pressure approximate model.

Abstract: An internally circulating fluidized bed (ICFB) was applied to investigate the behavior of refuse derived fuels (RDF) incineration. The temperature distribution along bed height was measured by the thermocouple and the pollutant emissions in the flue gas were measured by Fourier transform infrared spectrometry Gasmet DX-3000. In the tests the concentrations of the species CO CO2 HCl N2O SO2 were measured online. The experimental results showed that the RDF could combust steadily in the fluidized bed. The concentrations of the CO HCl N2O in flue gas were higher than the values of national environmental standards.

Abstract: Thermomagnetic convection of air in a porous cubic enclosure with an electric coil inclined around the X axis is numerically investigated under zerogravity environment. The porous cubic enclosure is heated isothermally from left-hand side vertical wall and cooled isothermally from opposing wall while the other four walls are thermally insulated. The governing equations in primitive variables are discretized by the finite-volume method and solved by the SIMPLE algorithm. The results show that the overall heat transfer is enhanced gradually with the increase of magnetic force number and Darcy number. The resulted convection is symmetrical in terms of the inclination angle at xeuler =45 when the range of inclination angle is from 0 to 90 .

Abstract: This paper presented an analysis for the couette flow of a generalized Oldroyd-B fluid within an infinite cylinder subject to a time-dependent shear stress with the influence of the internal constantly decelerated pressure gradient. The exact solutions are established by means of the combine of the sequential fractional derivatives Laplace transform and finite Hankel transform and presented by integral and series form in terms of the Mittag-Leffler function. Moreover, the effects of various parameters are analyzed in detail by graphical illustrations.

Abstract: A new clean-up technology for sedimentation basins is proposed in this paper adopting the stir-separation principle in which a clean-up bench for the analog sedimentation basin is designed according to the similarity principle and the flow field inside the tank is studied with the PIV experimental method. The results indicate that the mixture coefficient of the jet is 0.7 under different jet pressures, the fluid boundary sprayed from the combining tube of the jet is a straight line, the angle of the jet outflow is the same as that of the jet and the flow velocity of water is less than 0.1m/s in the area more than 1m away from the spouting tube. Meanwhile, the axial velocities of the jet from the jet at different Res are also measured and the semi-empirical formula is regressed.

Abstract: Numerical computations were carried out for theromagnetic convection of air in a square enclosure under both magnetising and gravitational fields. Scalar magnetic potential method was used to calculate magnetic field. The governing equations in primitive variables were discretized by the finite-volume method and solved by the SIMPLE algorithm. The flow and temperature fields for the air natural convection were presented and the local and mean Nusselt numbers on the walls were calculated and compared. The results show that the magnetic force has significant effect on the flow field and heat transfer in a square enclosure, the average Nusselt number respects the trend of decrease first and then increase when the magnetic force number increases.

Abstract: The essay introduces principles, forms and characteristics of the soil source heat pump system, explores applicability problems of the soil source heat pump system in cold areas, raises several ways to improve technology problems in the actual running of the soil source heat pump, briefly analyzes from the economic perspective in an combination of relevant materials, and points out that the soil source heat pump has certain applicability in cold areas.