Temperature Dependent Maximization Of Power And Opti- Mized Efficiency In Quantum Stirling Heat Engine

Abstract

In this thesis, we take a temperature dependent maximization of power and an optimized e ciency of quantum Stirling heat engine based on harmonic oscillators as the working medium. A quantum Stirling heat engine with an ensemble of harmonic oscillators as the working medium, studied for an isothermal operation at low temperatures limit. The power and e ciency of the heat engine are derived analytically as functions of the oscillator's frequencies. Using the optimization methods suggested by A.C Hernandez et.al, the heat engine is e ectively optimized and found to yield better working conditions in some ranges of frequency. In the low temperature limit, the gure of merit, a quantity de ned as a product of scaled power and scaled e ciency, , was found to be greater than 1 ( > 1 ) in range of 0 < ! 1:414 and less than 1 ( < 1) for all 1:414 < ! 2:042 It means that in some ranges of the ratios, it is found to work better in the optimized condition where as in other ranges it better performs under maximum power working condition. So, it is possible to switch the engine between the two scenarios.