Search

Abstract Single-fluid nozzles and dual-fluid nozzles are the two typical jet crushing methods used in spray dust reduction. To distinguish the atomization mechanism of single-fluid and dual-fluid nozzles and improve dust control efficiency at the coal mining faces, the atomization characteristics and dust reduction performance of the two nozzles were quantitatively compared. Results of experiments show that, as water supply pressure increased, the atomization angle of the swirl pressure nozzle reaches a maximum of 62° at 6 MPa and then decreases, but its droplet size shows an opposite trend with a minimum of 41.7 μm. The water supply pressure helps to improve the droplet size and the atomization angle of the internal mixing air–liquid nozzle, while the air supply pressure has a suppressive effect for them. When the water supply pressure is 0.2 MPa and the air supply pressure reaches 0.4 MPa, the nozzle obtains the smallest droplet size which is 10% smaller than the swirl pressure nozzle. Combined with the dust reduction experimental results, when the water consumption at the working surface is not limited, using the swirl pressure nozzle will achieve a better dust reduction effect. However, the internal mixing air–liquid nozzle can achieve better and more economical dust reduction performance in working environments where water consumption is limited.

Interior permanent magnet synchronous motor (IPMSM) is applied in automotive drive because of its high efficiency and high power density. The accurate torque control of motor, however, is still subject to further investigation and improvement. In order to improve the performance of IPMSM applied in electric vehicles, a feedback torque control method based on online parameter identification is developed in this research. In order to control the instantaneous electromagnetic torque accurately, stator resistance, rotor flux, and dq-axis inductance are identified simultaneously with a recursive least square algorithm. In this process, sinusoidal disturbance current is injected into d-axis to solve the rank-deficient problem. Furthermore, a simulation model is developed based on this torque control method. The simulation results show that the torque control method developed in this research can perform better than the torque control method based on fixed parameters. On the other hand, a test rig is developed in this research to verify the feasibility of torque control method and the effectiveness of simulation model. The measured results show that these parameters can be identified accurately with the online parameter identification method developed in this research, and the robustness of this online parameter identification method can be verified in the experiment. Furthermore, the torque control method is verified with this test rig, and the results show that the measured torque can accurately follow the torque command rapidly with little fluctuation, indicating that the method developed in this research has the features of high accuracy, high robustness and short response time.