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

Delfino Ladino-Luna

doi:10.3390/e7010108

Abstract

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.

Highlights

In classical equilibrium thermodynamics the efficiency of a reversible thermal engine operating between two reservoirs, at temperatures T1w > T2w, is known to be: ηC= 1 − T2w T1w (1.1)Entropy 2005, 7[1]In this description the temperatures of the working substance along the isothermal branches, T1w, i = 1,2, are assumed to be the same as the corresponding reservoirs; as a consequence the processes associated with the heat transfer between the engine and the reservoirs are ignored
By taking into account the time explicitly for all the branches of the cycle in terms of thermodynamic properties, and with the heat transfer Newton's law, Gutkowics-Krusin et al.[31] have shown that the Curzon and Ahlborn-Novikov efficiency ηCAN is an upper bound for the efficiency as a function of both the ratio β and the ratio of the maximum and the minimum volume spanned by the cycle, through the quantity ln
Ladino-Luna[33] has shown that ecological function has the same form in [14] if it is taken as working substance a van der Waals gas as well as it is using an ideal gas as the working substance, in the case of Newton heat transfer law, by taking the change V → V − b, where b is a constant that depends on the system

Summary

Introduction

By taking into account the time explicitly for all the branches of the cycle in terms of thermodynamic properties, and with the heat transfer Newton's law, Gutkowics-Krusin et al.[31] have shown that the Curzon and Ahlborn-Novikov efficiency ηCAN is an upper bound for the efficiency as a function of both the ratio β and the ratio of the maximum and the minimum volume spanned by the cycle, through the quantity ln Ladino-Luna[33] has shown that ecological function has the same form in [14] if it is taken as working substance a van der Waals gas as well as it is using an ideal gas as the working substance, in the case of Newton heat transfer law, by taking the change V → V − b , where b is a constant that depends on the system.

Results

Conclusion