Effects of Lovelock gravity on the Joule–Thomson expansion

Abstract

Effects of Lovelock gravity on the Joule-Thomson expansion are probed from various perspectives. The well-known Joule-Thomson coefficient is derived with both the explicit expression and intuitive image presented. Moreover, the inversion curves showing the relation between the inversion temperature and the inversion pressure are studied. It is shown that for given inversion pressure, the inversion temperature of the case α = 0 (α is the Lovelock parameter) is much lower than that of the case α = 0. And the inversion temperature tends to decrease with α, in contrast to the effect of the electric charge. It is also shown that the ratio between the minimum inversion temperature and the critical temperature decreases with α for α = 0. Furthermore, the isenthalpic curves are investigated with rich physics revealed. The intersection point between the isenthalpic curve and the inversion curve is exactly the inversion point discriminating the heating process from cooling process. It is shown that both the inversion temperature and the inversion pressure for α = 0 are much lower for the same given mass of the black hole, showing the effect of Lovelock gravity. Last but not the least, we discuss the case of uncharged Lovelock AdS black holes with interesting feature found. It is shown that the Joule-Thomson coefficient is always positive, suggesting the expansion is always in the regime of cooling process. And no inversion temperature exists, in contrast to the case Q = 0. Isenthalpic curves are also quite different since the temperature increases monotonically with the pressure when the mass is specified.

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.…”