  In this work, we investigate the thermoelectric properties of a hybrid
junction realised coupling surface states of a three-dimensional topological
insulator with a conventional $s$-wave superconductor. We focus on the
ballistic devices and study the quasiparticle flow, carrying both electric and
thermal currents, adopting a scattering matrix approach based on conventional
Blonder-Tinkham-Klapwijk formalism. We calculate the cooling efficiency of the
junction as a function of the microscopic parameters of the normal region (i.e.
the chemical potential etc.). The cooling power increases when moving from a
regime of Andreev specular-reflection to a regime where Andreev
retro-reflection dominates. Differently from the case of a conventional N/S
interface, we can achieve efficient cooling of the normal region, without
including any explicit impurity scattering at the interface, to increase normal
reflection.
