Joule-Thomson expansion of d -dimensional charged AdS black holes

Abstract

Effects of the dimensionality on the Joule-Thomson expansion are discussed in detail by considering the case of d-dimensional charged AdS black holes. Specifically, we investigate three important aspects characteristic of the Joule-Thomson expansion. Namely, the Joule-Thomson coefficient, the inversion curves and the isenthalpic curves. We utilize two different approaches to derive the explicit expression of the Joule-Thomson coefficient and show that both approaches are consistent with each other. The divergent point and the zero point of the Joule-Thomson coefficient are discussed. The former is shown to reveal the information of Hawking temperature while the latter is depicted through the so-called inversion curves. Fine structures of the inversion curves are disclosed in the cases d > 4. At low pressure, the inversion temperature increases with the dimensionality d while at high pressure it decreases with d. The ratio between minimum inversion temperature Tmin and the critical temperature Tc is discussed with its explicit expression obtained for d > 4. Surprisingly, it is shown that the ratio is not always equal to 1/2 but decreases with the dimensionality d. Moreover, isenthalpic curves of d > 4 are shown to expand toward higher pressure when the dimensionality d increases.

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.…”