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 $T_{min}$ and the critical temperature $T_c$ 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.

Comments welcome. 11pages, 5figures