Abstract A Carnot cycle outside a Schwarzschild black hole is investigated in detail. We propose a reversible Carnot cycle with a black hole being the cold reservoir. In our model, a Carnot engine operates between a hot reservoir with temperature T1 and a black hole with Hawking temperature TH. By naturally extending the ordinary Carnot cycle to the black hole system, we show that the thermal efficiency for a reversible process can reach the maximal efficiency 1-TH/T1. Consequently, black holes can be used to determine the thermodynamic temperature by means of the Carnot cycle. The role of the atmosphere around the black hole is discussed. We show that the thermal atmosphere provides a necessary mechanism to make the process reversible.
Received: 21 June 2008
Revised: 11 July 2008
Accepted manuscript online:
PACS:
04.70.Dy
(Quantum aspects of black holes, evaporation, thermodynamics)
Fund: Project supported by
the National Natural Science Foundation of China (Grant No
10605006), and the Scientific Research Starting Foundation for the
Returned Overseas Chinese Scholars, Ministry of Education, China,
and the Undergraduate Research Foundation
Cite this article:
Deng Xi-Hao(邓熙浩) and Gao Si-Jie(高思杰) Reversible Carnot cycle outside a black hole 2009 Chin. Phys. B 18 927
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