Polytropic black hole as a heat engine

Recently we have found an asymptotically AdS solution for Einstein's equations, those of thermodynamics match those of a special case of polytropic gas (Setare and Adami in Phys Rev D 91: 084014, 2015). Here we show that a polytropic black hole can be considered as a heat engine and then we calculatework done by this system and its efficiency.