Van der Waals gas as working substance in a Curzon and Ahlborn-Novikov engine

Using a van der Waals gas as the working substance the so called Curzon and Ahlborn-Novikov engine is studied. It is shown that some previous results found in the literature of finite time thermodynamics can be written in a more general form, means of this gas and by taking a non linear heat transfer law. 1. Introduction In classical equilibrium thermodynamics the efficiency of a reversible thermal engine operating between two reservoirs, at temperatures