Yuyu Xu

Permanent Magnet Type Eddy Current Heater Based on Cylindrical Halbach Array for Reducing Oil's Viscosity

The eddy current, Joule heat and input electrical power of a permanent magnet type eddy current heater based on cylindrical Halbach arrays to reduce the viscosity of crude oil in oil wells were analysed and studied by means of a three-dimensional finite-element method. The results show that when Halbach arrays generate a 0.9 T sinusoidal static field and the annulus conductor is copper, the Joule heat is about 575 W/m for a relative translational motion of 0.5 m/s in direction. The thermal efficiency of the heater is about 77.6%.

End effect of liquid metal magnetohydrodynamic generator in wave energy direct conversion system

The influence of end effect on electromotive force, induced magnetic field and flow loss of the reciprocating liquid metal magnetohydrodynamic (LMMHD) generator was investigated. The 3D numerical simulation was done firstly, then the electromagnetic and flow performances predicted from quasi-2D and 3D analyses were compared and three end influence coefficients quantifying end effect were defined. Factors influencing end effect were analyzed and new method to suppress the end effect was proposed in the end. The study shows that the end gradient of the external magnetic field and end leakage current are main causes of the end effect in the LMMHD generator. The velocity in MHD channel and end gradient of the applied magnetic field are two key factors affecting the end effect greatly. The integration of insulating vane and low end gradient of the applied magnetic field can effectively suppress the end current and decrease energy losses.

Design Study on a Large Force Superconducting Linear Driver

A tubular superconducting linear driver with a conduction-cooled opposite-poles solenoid superconducting magnet and a DC resistive coil that can generate a large axial force was presented in this paper. Design and analysis of a demonstration tubular superconducting linear driver were conducted. The results show that the tubular superconducting linear driver is able to generate an axial force of 10 kN with stroke of 0.25 m.

Analytical Study on End Effect of Liquid Metal MHD Generator

End effect causes much energy loss in MHD power generator duo to the external magnetic field in the end region of the effective MHD channel. It is effective to lessen the end loss using a tapered magnetic field and a tapered flow channel outside the electrode. An analysis in theory has been given first, and then some numerical simulations have been carried out. The results show that even without a uniform magnetic field in all channels, the influence of end effect has been weakened greatly with no return-path current and little eddy current when using a trapezoidal magnetic field and a trapezoidal geometry of flow channel.

Study on Oil Separation and Recovery from Oil- Contaminated Seawater by MHD Method

A new method for oil separation and recovery from oil-contaminated seawater, based on electromagnetic force in an MHD flow train, was studied in IEECAS since 2002. The oilcontaminated seawater has two typical cases: one is oil-spill floating on offing, other is oil droplets mixed well with seawater. The MHD flow trains for oil separation to both cases above were designed and investigated in IEECAS. For the first case, a te est fa ac cil li ity y a as s we ell l a as s a m mo od del l s sh hip p c comprisin ng a permane ent t ma ag gn net t, , a an n MH HD c cha an nnel and d a a s se epar rating g t tank k was s bui ildu up. . Oil recovery rate of 72 kg/h with the containing water ratio less than 5% was obtained with the MHD channels section of 29X40mm2, magnetic field of 0.8T, working current of about 13A in experiment.Dem mons st trati ion experi im me ent was suc cce ess sf ful lly car rried d out t, wh hic ch p pro ov ve es t tha at t t the e M MHD oil l spi il ll r rec cover ry m meth hod i is ef ffec cti ive to o s sol lve th he s sea aw water r poll lution w wit th oil-spill floating on offing. For the second case, an MHD oil droplets mixture separation experiment w was jo oi in ntly c cond duc cte ed in 2006 b by IEECAS and FMSKU. Using a mixture of artificial seawater and simulation particles, the experimental results show that the separation ratio increases as current increasing at a constant magnetic field, particle diameter and flow rate. A perfect separation can be reached when the particle diameter is smaller, and a separation ratio of 99.45% has been reached in the experiment when the diameter is 0.5mm at the working current of 2A and magnetic field of 10T.