Charged torus-like black holes as heat engines

Hanwen Feng,Yuchen Huang,Wei Hong,Jun Tao

Figure 6. Efficiency of the charged torus-like black hole calculated with the numerical method. Here we set the circle origin at Vo = 110 and Po = 20, the charge Q = 20.0 and radius R = 10.0. The efficiency equals to 0.587 226 when N = 500.