Modelling of heat removing from submersible motor with magnetic clutch

Аuthors

Gizatullin R. R.^1*, Peshcherenko M. P.², Peshcherenko S. N.¹

1. Perm National Research Polytechnic University, PNRPU, 29, Komsomolsky Prospekt, Perm, 614990, Russia
2. "Novomet-Perm", Perm

*e-mail: gizatullin.rr@novomet.ru

Abstract

The main method of structural reliability increase of submersible motors (SM) is their air- tightness ensuring. There are two possibilities for this. The first one consists in enclosing rotor and stator in individual sealed shells. The disadvantage of this method is gap increasing be- tween rotor and stator, and, thus, the unavoidable motor efficiency reduction. The second possibility consists in encasing the whole motor in the sealed case, and transferring rotation from the SM to the pump by the magnetic clutch.

The article suggests the technique of numerical modeling of heat removal from motor and magnetic coupling. The heat release in magnetic coupling occurs only due to the internal friction in the rotor-stator gaps, while in SM the electromagnetic losses should be accounted for also. The temperature and pressure field were computed for various cooling methods. The magnetic clutch cooling system parameters were determined. It was demonstrated that the oil pumping, necessary for the clutch bearings lubrication only, should be limited to its minimum from the MS side. The heat is removed by the borehole fluid (a water and oil mixture) from the pump side.

Moreover, with a borehole fluid effective viscosity of less than 60 Pa∙s, the supply may be no more than 3-5 m3/day. If the of the borehole fluid effective viscosity is more than 60 Pa∙s, it should be separated before pumping into the magnetic clutch, otherwise the pressure created by the liquid on the protective sleeve of the clutch will exceed 0.3 MPa, which significantly limits the selection of dielectric materials employed for making the sleeve.

Keywords:

magnetic coupling, hermetic motor, viscous oil, internal friction, heat transfer