  The effects of nonequilibrium ionization are explicitly taken into account in
a numerical model which describes colliding stellar winds (CSW) in massive
binary sytems. This new model is used to analyze the most recent X-ray spectra
of the WR+OB binary system WR 147. The basic result is that it can adequately
reproduce the observed X-ray emission (spectral shape, observed flux) but some
adjustment in the stellar wind parameters is required. Namely, (i) the stellar
wind velocities must be higher by a factor of 1.4 - 1.6; (ii) the mass loss
must be reduced by a factor of ~ 2. The reduction factor for the mass loss is
well within the uncertainties for this parameter in massive stars, but given
the fact that the orbital parameters (e.g., inclination angle and eccentricity)
are not well constrained for WR 147, even smaller corrections to the mass loss
might be sufficient. Only CSW models with nonequilibrium ionization and equal
(or nearly equal) electron and ion postshock temperature are successful.
Therefore, the analysis of the X-ray spectra of WR 147 provides evidence that
the CSW shocks in this object must be collisionless.
