Simulation and analysis of O_(2)-CaO jet behavior with different shrouding fuel mediums in electric arc furnace steelmaking

The O_(2)-CaO jet with shrouding combustion flame demonstrates some advantages in quick melting and effective slag foaming by delivering lime powder deeply into the molten bath.Combining the discrete particle model and the eddy dissipation concept model with the detailed chemical kinetic mechanisms(GRI-Mech 3.0),computational fluid dynamics models of the O_(2)-CaO jet with different shrouding fuel mediums injection were developed.Firstly,the results of the numerical simulation were validated by the measured data of cold test for O_(2)-CaO injection.Then,the interaction between the particles and the gas jet of the O_(2)-CaO jet and the effect of shrouding fuel medium species on the fluid flow characteristics of the O_(2)-CaO jet were analyzed.Results show that the CaO particles can be effectively heated by the shrouding high-temperature combustion flame and compared with the O_(2)-CaO jet without shrouding gas,the potential core length was increased about 2.5,3.3 and 4.3 times by the shrouding flame generated from CO,CH_(4) and C_(3)H_(8).And with shrouding CH_(4) and C_(3)H_(8) injection,the CaO particles can be clustered together in a long distance,which would be helpful to improve the utilization efficiency of CaO particles.

Constraints on cosmic-ray boosted dark matter in CDEX-10

Dark matter(DM)direct detection experiments have been setting strong limits on the DM-nucleon scattering cross section at the DM mass above a few GeV,but leave large parameter spaces unexplored in the low mass region.DM is likely to be scattered and boosted by relativistic cosmic rays in the expanding universe if it can generate nuclear recoils in direct detection experiments to offer observable signals.Since low energy threshold detectors using Germanium have provided good constraints on ordinary halo GeV-scale DM,it is necessary to re-analyze102.8 kgxday data in the CDEX-10 experiment assuming that DM is boosted by cosmic rays.For the DM mass range 1 keV<m_(χ)<1 MeV and the effective distance within 1 kpc,we reach an almost flat floor limit at8.32×10^(-30) cm^(2) for the spin-independent DM-nucleon scattering cross section,at a 90%confidence level.The CDEX-10 result is able to close the gap unambiguously in the parameter space between the MiniBooNE and XENON IT constraints,which were partially hindered by the Earth attenuation effect.We also quantitatively calculate the expected neutrino floor on searching for CRBDM in future direct detection experiments using Germanium.