  We employ an effective-field theory with correlations in order to study a
magnetocaloric effect on a triangular Ising antiferromagnet, which is
selectively diluted by non-magnetic impurities on one of the three sublattices.
Such a dilution generally relieves massive degeneracy in our system and
therefore the ground-state entropy diminishes and the magnetocaloric effect
weakens at low temperatures. However, at relatively higher temperatures we can
observe significantly enhanced negative isothermal entropy changes for the
sublattice concentration $p_{\mathrm{A}} = 0.8$.
