Optimal use of energy systems and processes

In the present paper we focus on two items, Energy, and Environment. We propose to restore and extend the view of CARNOT, relative to thermomechanical systems and processes, starting from thermostatics (equilibrium thermodynamics), through what was first developed as Finite Time Thermodynamics (FTT), since the 1980s (nice radical of Chambadal – Novikov – Curzon – Ahlborn), until now. The CARNOT machine is revisited in the presence of heat transfer irreversibilities as well as internal irreversibility, and heat loss. Classical results are recovered. New bounds are developed when constraints are added; these constraints are related to useful effect, energy consumption, or machine efficiency. A new form of 'nice radical' is proposed when energy consumption is imposed. New results are proposed with different added constraints.