Joule-Thomson expansion of charged Gauss-Bonnet black holes in AdS space

Abstract

Joule-Thomson expansion process is studied for charged Gauss-Bonnet black holes in AdS space. Firstly, in five-dimensional space-time, the isenthalpic curve in T − P graph is obtained and the cooling-heating region is determined. Secondly, the explicit expression of Joule-Thomson coefficient is obtained from the basic formulas of enthalpy and temperature. Our methods can also be applied to van der Waals system as well as other black hole systems. And the inversion curveT (P ) which separates the cooling region and heating region is obtained and investigated. Thirdly, interesting dependence of the inversion curves on the charge (Q) and the Gauss-Bonnet parameter (α) is revealed. InT −P graph, the cooling region decreases with charge, but increases with the Gauss-Bonnet parameter. Fourthly, by applying our methods, the Joule-Thomson expansion process for α = 0 case in four dimension is studied, where the Gauss-Bonnet AdS black hole degenerates into RN-AdS black hole. The inversion curves for van der Waals systems consist of two parts. One has positive slope, while the other has negative slope. However, for black hole systems, the slopes of the inversion curves are always positive, which seems to be a universal feature. *

Joule-Thomson expansion in AdS black holes with momentum relaxation

“…We have observed that for the case of linear axions, when they possess standard kinetic term, the inversion curve possesses only one branch, similar to what was obtained in [32][33][34][35][36][37], behavior that differs from the case of Van der Wall fluids. The net effect of the momentum relaxation mechanism, which is controlled by our coupling β, is that the inversion curve is enlarged for higher values of β.…”

“…Furthermore, we study the isenthalpic curves for c 1 = −1 and These observations are novel in the following aspects. Comparing with previous works [32][33][34][35][36][37], where only one branch was obtained, we first obtain two branches for the inversion curve, which is similar to the Van der Waals fluids case. However, the minimal inversion temperature is negative unlike the case of Van der Waals fluids.…”

“…There is only one branch of inversion curves as that studied in [32][33][34][35][36][37], which differ from the one obtained for Van der Waals fluids. As momentum increases, the curve is higher.…”

“…Respect to previous works, for the uncharged case we observe that for some values of the relevant parameters we obtained two branches, similar to what is obtained for Van der Wall fluids but with a minimum inversion temperature that takes a negative value. Moreover when constructing the isenthlapic curves we observe that the inversion point represent a minimum of the isenthalpic curve instead of a maximum as it has been typically found [32][33][34][35][36][37]. This implies that in the left side of the inversion curve, the isenthalpic process is a cooling process while it is a warming process in the right side.…”

“…The study of Joule-Thomson expansion has been generalized for several black hole solutions including arbitrary dimensional charge AdS black hole [33], Kerr-AdS black holes [34], Gauss-Bonnet AdS black holes [35], Lovelock gravity [36] and nonlinear electrodynamic gravity [37] to mention few examples.…”