A flywheel energy storage system (FESS) uses a high speed spinning mass (rotor) to store kinetic energy. The energy is input or output by a dual-direction motor/generator. To maintain it in a high efficiency, the flywheel works within a vacuum chamber. Active magnetic bearings (AMB) utilize magnetic force to support rotor's rotating shaft without mechanical friction. It also makes the rotor more dynamically controllable.A prototype of FESS with AMBs was developed. Dynamical model is obtained and analyzed for the rotor-bearing system. Control method is determined in accord with the dynamical characteristics of the flywheel. AMB's parameters are obtained by parameter identification. Influences of the magnetic force on the nutation and procession of the flywheel rotor, and of the controller to the stability of the dynamical system were analyzed.Experiment has been undertaken. The flywheel has steadily past through its flexible critical speed and reached to the rotating speed of 28500RPM. Maximum tip speed is 450m/s. Maximum electrical discharge power reaches 40W. Discharge duration is 100 minutes.
Plasma-facilitated selective catalytic reduction(PF-SCR) was considered as a promising method to realize controlling of NO x in the lean-burn engine exhaust. But the influences of power frequency lack detailed description. Powers with frequency 50Hz, 800Hz and 10kHz were applied respectively to produce plasma in the experiments, and twostage process consisting of plasma pretreatment of the exhaust before flow over a lean NO x catalyst was studied. The results showed that 50Hz power was more efficient on NO x removal than other two power supplies according to energy density. It may be attributed to that highest voltage was supplied by 50Hz power in the three powers at the same energy density, which led to more NO and C 2 H 4 oxidation after plasma. As a result, NO 2 , more active reactant than NO, was produced more by 50Hz power. The gas components in the exit of plasma reactor were identified by GC-MS and GC, and the transforming routes of nitrogen element and carbon element were also concluded simply.
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