Heat engines at criticality for nonlinearly charged black holes

Abstract

Within the extended phase–space thermodynamics, we study heat engines in power Yang–Mills and power Maxwell black holes at criticality, as the corresponding nonlinearity power parameters [Formula: see text] and [Formula: see text] are varied. For the computation of efficiency of such engines, starting from power Maxwell black holes, a map is proposed for carrying out the computations in power Yang–Mills theories. On comparison, the approach of efficiency of heat engines to Carnot limit in both the systems is shown to coincide when [Formula: see text], but, for [Formula: see text], Maxwell (Yang–Mills) system dominates over Yang–Mills (Maxwell). Higher values of [Formula: see text] aid in improving the approach of efficiency to Carnot limit for Maxwell heat engines. On the contrary, efficiency in Yang–Mills heat engines approaches Carnot limit faster for lower values of the power [Formula: see text].