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.
