Amended FRW universe: thermodynamics and heat engine

Abstract

AbstractThermodynamics of non-flat Amended Friedmann–Robertson–Walker (AFRW) universe with cosmological constant as thermodynamic pressure is studied. The unified first law of thermodynamics, the Clausius relation and the gravity equations yield entropy on the dynamic apparent horizon. Temperature, volume, pressure, enthalpy, Gibb’s free energy and Helmholtz’s free energies, and specific heat capacity with constant pressure of the universe are calculated in terms of surface area of dynamic apparent horizon. The study shows a non-negative Joule–Thomson coefficient, indicating the cooling nature of the AFRW universe. Inversion pressure and inversion temperature are expressed in terms of the surface area of the apparent horizon. Finally, the thermodynamical AFRW universe is considered as a heat engine. Work done for the Carnot engine is derived with maximum efficiency, and a new engine is also considered for which the work done, and its efficiency are calculated for AFRW universe.