  As a neutron star spins down, its core density increase, changing the
relative equilibrium concentration, and causing deconfinement phase transition
as well. hadron matter are converted into quark matter in the interior, which
enhances the deviation of chemical equilibrium state. We study such deviations
and its chemical energy release.Applying to the simulation of cooling neutron
stars, we find the surface effective temperature of neutron stars is promoted
obviously. This implies that the deconfinement phase transition is able to
raise the chemical heating efficiency.
