A new design of foam spray nozzle used for precise dust control in underground coal mines

In order to improve the utilization rate of foam,an arc jet nozzle was designed for precise dust control.Through theoretical analysis,the different demands of foam were compared amongst arc jets,flat jets and full cone jets when the dust source was covered identically by foam.It is proved that foam consumption was least when an arc jet was used.Foam production capability of an arc jet nozzle under different conditions was investigated through experiments.The results show that with the gas liquid ratio(GLR)increasing,the spray state of an arc jet nozzle presents successively water jet,foam jet and mist.Under a reasonable working condition range of foam production and a fixed GLR,foam production quantity increases at first,and then decreases with the increase of liquid supply quantity.When the inner diameter of the nozzle is 14 mm,the best GLR is 30 and the optimum liquid supply quantity is0.375 m^3/h.The results of field experiments show that the total dust and respirable dust suppression efficiency of arc jet nozzles is 85.8%and 82.6%respectively,which are 1.39 and 1.37 times higher than the full cone nozzles and 1.20 and 1.19 times higher than the fiat nozzles.

On the trajectory of nonturbulent liquid jets in subsonic crossflows at different density ratios

Numerical simulations using volume of fluid(VOF)method are performed to study the impact of liquid-to-gas density ratio on the trajectory of nonturbulent liquid jets in gaseous crossflows.In this paper,large eddy simulation(LES)turbulence model is coupled with the VOF method to describe the turbulence effects accurately.In addition,dynamic adaptive mesh refinement method with two refinement levels is applied to refine the size of the cells located at gas-liquid interface.Density ratio is changed from 10 to 5000 while other nondimensional numbers are kept constant.Large density ratios are considered in this paper since they are common in many practical applications such as solution precursor/suspension plasma sprays.Our simulations show that the penetration height,especially in the farfield,increases as the density ratio increases.A general correlation for the jet trajectory,which can be used for a wide range of density ratios,is developed based on our simulation results.

Synthesis of In_2S_3 thin films by spray pyrolysis from precursors with different[S]/[In] ratios

Indium sulfide （InzS3） thin films were prepared by chemical spray pyrolysis technique from solutions with different [S]/[In] ratios on glass substrates at a constant temperature of 250 ~C. Thin films were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, atomic force microscopy （AFM）, energy disper- sive X-ray spectroscopy （EDS）, Raman spectroscopy and optical transmittance spectroscopy. All samples exhibit a polycrystalline structure with a preferential orientation along （0, 0, 12）. A good stoichiometry was attained for all samples. The morphology of thin film surfaces, as seen by SEM, was dense and no cracks or pinholes were ob- served. Raman spectroscopy analysis shows active modes belonging to j3-1naS3 phase. The optical transmittance in the visible range is higher than 60% and the band gap energy slightly increases with the sulfur to indium ratio, attaining a value of 2.63 eV for [S]/[In] ： 4.5.

Multi-Component Model of Diesel Sprays Under High Injection Pressure

The combustion efficiency of a diesel engine depends not only on spray characteristics but also on fuel-air mixing characteristics. Based on the original spray model, a new spray model is established in this paper to accurately predict the diesel spray, and then a multi-component evaporation model is added into it. The model takes the influence of component concentration gradient and species on its evaporation rate in the liquid phase into account. This paper studies the spray characteristics(spray penetration, spray angle and spray morphology) and fuel-air mixing characteristics(spray area, spray volume and air entrainment mass) using the spray model, and the results are compared with the experimental results. The comparison shows that the simulated spray penetration and spray angle are close to the experimental results with the average deviations less than 3%. Moreover, this paper studies the spray area, spray volume and air entrainment using empirical formula under different conditions. And the maximum deviations of the spray volume, spray area and air entrainment mass are less than 5% as compared with the test values. Overall, this spray model can predict the diesel spray characteristics and fuel-air mixing characteristics under high injection pressure accurately.