No Arabic abstract
In this paper, we attempt to study the Joule-Thomson expansion for the regular black hole in an anti-de Sitter background, and obtain the inversion temperature and curve for the Bardeen-AdS black hole in the extended phase space. We investigate the isenthalpic and inversion curves for the Bardeen-AdS black hole in the T-P plane to find the intersection points between them are exactly the inversion points discriminating the heating process from the cooling one. And, the inversion curve for the regular(Bardeen)-AdS black hole is not closed and there is only a lower inversion curve in contrast with that of the Van der Walls fluid. Most importantly, we find the ratio between the minimum inversion and critical temperature for the regular(Bardeen)-AdS black hole is 0.536622, which is always larger than all the already-known ratios for the singular black hole. This larger ratio for the Bardeen-AdS black hole in contrast with the singular black hole may stem from the fact that there is a repulsive de Sitter core near the origin of the regular black hole.
In this paper, we study Joule-Thomson expansion for Hayward-AdS black hole in the extended phase space, and obtain a Joule-Thomson expansion formula for the black hole. We plot the inversion and isenthalpic curves in the T-P plane, and determine the cooling-heating regions. The intersection points of the isenthalpic and inversion curves are exactly the inversion points discriminating the heating process from the cooling one.
In this paper, we investigate the thermal stability and Joule-Thomson expansion of some new qusitopological black hole solutions. We first study the higher-dimensional static quasitopological black hole solutions in the presence of Born-Infeld, exponential and logarithmic nonlinear electrodynamics. The stable regions of these solutions are independent of the types of the nonlinear electrodynamics. The solutions with the horizons relating to the positive constant curvature, $k=+1$, have a larger region in thermal stability, if we choose positive quasitopological coefficients, $mu_{i}>0$. We also have a review on the power Maxwell quasitopological black hole. Then, we obtain the five-dimensional Yang-Mills quasitopological black hole solution and compare with the quasitopological Maxwell solution. For large values of the electric charge, $q$, and the Yang-Mills charge, $e$, we showed that the stable range of the Maxwell quasitopological black hole is larger than the Yang-Mills one. This is while thermal stability for small charges has the same behavior for these black holes. In the following, we obtain the thermodynamic quantities for these solutions and then study the Joule-Thomson expansion. We consider the temperature changes in an isenthalpy process during this expansion. The obtained results show that the inversion curves can divide the isenthalpic ones into two parts in the inversion pressure, $P_{i}$. For $P<P_{i}$, a cooling phenomena with positive slope happens in $T-P$ diagram, while there is a heating process with negative slope for $P>P_{i}$. As the values of the nonlinear parameter, $beta$, the electric and Yang-Mills charges decrease, the temperature goes to zero with a small slope and so the heating phenomena happens slowly.
In this paper we study Joule-Thomson $(JT)$ expansion of non-linearly charged $AdS$ black holes in Einstein-power-Yang-Mills (EPYM) gravity in $D$ dimensions. Within the framework of extended phase space thermodynamics we identify the cosmological constant as thermodynamic pressure and the black hole mass with the enthalpy and derive the Joule-Thomson coefficient $mu$. Furthermore we have presented equations for inversion curves and the exact expression for the minimum inversion temperature. We also have calculated the ratio between the minimum of inversion $T_i^{min}$ and the critical temperature $T_c$ and obtained the analytic expression for the ratio $frac{T_i^{min}}{T_c}$ that depends explicitly on the non-linearity parameter $q$ and dimension $D$. We consider the isenthalpic curves in the $T- P$ plane for different values of the fixed black hole mass and obtain heating and cooling region. Finally we have dealt with two limiting masses which characterizes the process of Joule-Thomson expansion in the $EPYM$ black holes.
If some energy conditions on the stress-energy tensor are violated, is possible construct regular black holes in General Relativity and in alternative theories of gravity. This type of solution has horizons but does not present singularities. The first regular black hole was presented by Bardeen and can be obtained from Einstein equations in the presence of an electromagnetic field. E. Ayon-Beato and A. Garcia reinterpreted the Bardeen metric as a magnetic solution of General Relativity coupled to a nonlinear electrodynamics. In this work show that the Bardeen model may also be interpreted as a solutions of Einstein equations in the presence of a electric source, whose electric field does not behaves as a Coulomb field. We analyzed the asymptotic forms of the Lagrangian for the electric case and also analyzed the energy conditions.
We investigate the thermodynamics of FRW (Friedmann-Robertson-Walker) universe in the extended phase space. We generalize the unified first law with a cosmological constant $Lambda$ by using the Misner-Sharp energy. We treat the cosmological constant as the thermodynamic pressure of the system, and derive thermodynamic equation of state $P = P(V, T)$ for the FRW universe. To clarify our general result, we present two applications of this thermodynamic equation of state, including Joule-Thomson expansions and efficiency of the Carnot heat engines. These investigations lead to physical insights of the evolution of the universe in view of thermodynamics.