In this paper, we consider the Kerr–Sen black hole. Unlike the AdS black hole, it is actually
an exact solution for the heterotic string theory in the low energy effective field theory in four
dimensions. Starting from the black hole metric in the Boyer–Lindquist coordinates, we
calculate the maximal interior volume by introducing the advanced time. Further, we present
the rate of change of the interior volume with the advanced time on the radius of the black
hole and observe that it has a maximal value for a specific value of the radius of the black …