The stochastic efficiency [G. Verley et al., Nat. Commun. 5, 4721 (2014)] was introduced to evaluate the performance of energy-conversion machines in micro-scale. However, such an generally diverges when no heat is absorbed while work produced a thermodynamic cycle. As result, any statistical moments do not exist. In this study, we come up with different version definition for which always fini...

The current paper examines the application of finite-time thermodynamics in order to compare the performance between air-standard cycles, i.e. Atkinson, Diesel and Otto cycles with constant specific heats of working fluid. The effects of input temperature and compression ratio on the net output work and efficiency of the Atkinson cycle, Diesel cycle and Otto cycle are analyzed. It is assumed th...

We derive cooling rate and coefficient of performance as well their variances for a quantum Otto engine proceeding in finite-time cycle period. This machine consists two driven strokes, where the system isolated from heat reservoir undergoes unitary transformation, isochoric steps, system-bath interaction durations take away equilibrium even at respective ends stages. explicitly calculate stati...

Algebraic methods for solving time-dependent Hamiltonians are used to investigate the performance of quantum thermal machines. We thermodynamic properties an engine formed by two coupled qubits, performing Otto cycle. The interaction occurs with baths at different temperatures, while work is associated arbitrary magnetic field that varies in intensity and direction. For coupling, we consider 1D...

The performance of an air-standard Otto cycle with variation of cycle peak temperature and variable specific heats of working fluid is analyzed. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between power output and the efficiency of the cycle are derived by detailed numerical examples....

For finite-time quantum Otto heat engine with working fluid consisting of either a (i) qubit or (ii) harmonic oscillator, we show that the relative fluctuation output work is always greater than corresponding input absorbed from hot bath. As result, ratio between and receives lower bound in terms square value average efficiency engine. The saturation received quasi-static limit can be shown for...