Charged AdS black hole heat engines

Starting from simple observations regarding heat flows for static black holes (or any thermodynamic system with [Formula: see text]), we get inequalities which restrict their change in energy and adiabatic curves in the [Formula: see text] plane. From these observations, we then derive an exact efficiency formula for virtually any holographic heat engine defined by a cycle in the [Formula: see text] plane, whose working substance is a static black hole. Moreover, we get an upper bound for its efficiency and show that for a certain class of black holes, this bound is universal and achieved by an “ideal gas” hole. Finally, we compute exact efficiencies for some particular and new engines.

Download Full-text

Massive gravity with Lorentz symmetry breaking: Black holes as heat engines

Modern Physics Letters A ◽

10.1142/s0217732318501778 ◽

2018 ◽

Vol 33 (31) ◽

pp. 1850177 ◽

Cited By ~ 2

Author(s):

Sharmanthie Fernando

Keyword(s):

Black Hole ◽

Symmetry Breaking ◽

Heat Engine ◽

Massive Gravity ◽

Lorentz Symmetry ◽

Extended Phase ◽

Heat Engines ◽

Static Black Hole ◽

Lorentz Symmetry Breaking ◽

Two Parameters

In extended phase space, a static black hole in massive gravity is studied as a holographic heat engine. In the massive gravity theory considered, the graviton gains a mass due to Lorentz symmetry breaking. Exact efficiency formula is obtained for a rectangle engine cycle for the black hole considered. The efficiency is computed by varying two parameters in the theory, the scalar charge Q and [Formula: see text]. The efficiency is compared with the Carnot efficiency for the heat engine. It is observed that when Q and [Formula: see text] are increased that the efficiency for the rectangle cycle increases. When compared to the Schwarzschild–AdS black hole, the efficiency for the rectangle cycle is larger for the massive gravity black hole.

Download Full-text

Black hole thermodynamics and heat engines in conformal gravity

International Journal of Modern Physics D ◽

10.1142/s0218271817501516 ◽

2017 ◽

Vol 26 (13) ◽

pp. 1750151 ◽

Cited By ~ 16

Author(s):

Hao Xu ◽

Yuan Sun ◽

Liu Zhao

Keyword(s):

Black Holes ◽

Black Hole ◽

Black Hole Thermodynamics ◽

Spherically Symmetric ◽

Conformal Gravity ◽

Extended Phase ◽

Heat Engines ◽

Equation Of States ◽

Symmetric Black Hole ◽

Black Hole Solutions

The extended phase-space thermodynamics and heat engines for static spherically symmetric black hole solutions of four-dimensional conformal gravity are studied in detail. It is argued that the equation of states (EOS) for such black holes is always branched, any continuous thermodynamical process cannot drive the system from one branch of the EOS into another branch. Meanwhile, the thermodynamical volume is bounded from above, making the black holes always super-entropic in one branch and may also be super-entropic in another branch in certain range of the temperature. The Carnot and Stirling heat engines associated to such black holes are shown to be distinct from each other. For rectangular heat engines, the efficiency always approaches zero when the rectangle becomes extremely narrow, and given the highest and lowest working temperatures fixed, there is always a maximum for the efficiency of such engines.

Download Full-text

Benchmarking black hole heat engines, I

International Journal of Modern Physics D ◽

10.1142/s0218271819500123 ◽

2018 ◽

Vol 27 (16) ◽

pp. 1950012 ◽

Cited By ~ 9

Author(s):

Avik Chakraborty ◽

Clifford V. Johnson

Keyword(s):

Black Holes ◽

Black Hole ◽

Exact Result ◽

Ideal Gas ◽

Heat Engines ◽

Gas System

We present the results of initiating a benchmarking scheme that allows for cross-comparison of the efficiencies of black holes used as working substances in heat engines. We use a circular cycle in the [Formula: see text] plane as the benchmark engine. We test it on Einstein–Maxwell, Gauss–Bonnet and Born–Infeld black holes. Also, we derive a new and surprising exact result for the efficiency of a special “ideal gas” system to which all the black holes asymptote.

Download Full-text

Effects of the external string cloud on the Van der Waals-like behavior and efficiency of AdS-Schwarzschild black holes in massive gravity

Modern Physics Letters A ◽

10.1142/s021773232050203x ◽

2020 ◽

Vol 35 (24) ◽

pp. 2050203

Author(s):

M. Ghanaatian ◽

Mehdi Sadeghi ◽

Hadi Ranjbari ◽

Gh. Forozani

Keyword(s):

Phase Transition ◽

Black Holes ◽

Black Hole ◽

Van Der Waals ◽

Black Hole Entropy ◽

Five Dimensions ◽

Four Dimensions ◽

Heat Engines ◽

Cloud Parameter ◽

Extremal Black Holes

In this paper, we study AdS-Schwarzschild black holes in four and five dimensions in dRGT minimally coupled to a cloud of strings. It is observed that the entropy of the string cloud and massive terms does not affect the black hole entropy. The observations about four dimensions indicate that the massive term in the presence of external string cloud cannot exhibit Van der Waals-like behavior for AdS-Schwarzschild black holes and, therefore there is only the Hawking–Page phase transition. In contrast, in five dimensions, the graviton mass modifies this behavior through the third massive term, so that a critical behavior and second-order phase transition is deduced. Also, the Joule–Thomson effect is not observed. The black hole stability conditions are also studied in four and five dimensions and a critical value for the string cloud parameter is presented. In five dimensions a degeneracy between states for extremal black holes is investigated. After studying black holes as thermodynamic systems, we consider such systems as heat engines, and finally the efficiency of them is calculated.

Download Full-text

Thermodynamics and heat engines of black holes with Born–Infeld-type electrodynamics

Modern Physics Letters A ◽

10.1142/s0217732321501029 ◽

2021 ◽

pp. 2150102

Author(s):

Leonardo Balart ◽

Sharmanthie Fernando

Keyword(s):

Black Holes ◽

Black Hole ◽

Phase Transitions ◽

Heat Engine ◽

Nonlinear Electrodynamics ◽

Extended Phase ◽

Charged Black Holes ◽

Heat Engines ◽

Two Parameters ◽

Electrically Charged

In this paper, we have studied electrically charged black holes in a new model of nonlinear electrodynamics introduced by Kruglov in Mod. Phys. Lett. A 32, 1750201 (2017). There are two parameters for the theory and the black hole could have up to two horizons. Thermodynamics is studied in the extended phase space where the pressure is proportional to the cosmological constant. First law and the Smarr formula are derived. There are phase transitions similar to the Van der Waals liquid-gas phase transitions. Black hole is also studied as a heat engine and we have discussed how the parameters in the nonlinear electrodynamics theory affect the efficiency of the heat engine.

Download Full-text

Benchmarking black hole heat engines, II

International Journal of Modern Physics D ◽

10.1142/s0218271819500068 ◽

2018 ◽

Vol 27 (16) ◽

pp. 1950006 ◽

Cited By ~ 7

Author(s):

Avik Chakraborty ◽

Clifford V. Johnson

Keyword(s):

Black Holes ◽

Black Hole ◽

Angular Velocity ◽

Upper Bound ◽

Exact Formula ◽

Ideal Gas ◽

Static Case ◽

Rotating Black Hole ◽

Heat Engines ◽

Ads Black Holes

We extend to nonstatic black holes our benchmarking scheme that allows for cross–comparison of the efficiencies of asymptotically AdS black holes used as working substances in heat engines. We use a circular cycle in the [Formula: see text] plane as the benchmark cycle. We study Kerr black holes in four spacetime dimensions as an example. As in the static case, we find an exact formula for the benchmark efficiency in an ideal gas-like limit, which may serve as an upper bound for rotating black hole heat engines in a thermodynamic ensemble with fixed angular velocity. We use the benchmarking scheme to compare Kerr to static black holes charged under Maxwell and Born–Infeld sectors.

Download Full-text