Performance of 3D quantum Otto engine with partial thermalization

Abstract

We investigate the phenomenon of partial thermalization in the context of the efficiency at maximum power (EMP) for a quantum Otto engine. This engine utilizes Bose-Einstein Condensation in a cubic potential. The occurrence of partial thermalization is observed during a finite-time isochoric process, preventing the system from reaching an equilibrium state with the reservoirs and leaving it in a state of residual coherence. The engine’s performance can be evaluated based on its power output and EMP. The cubic potential is employed to induce energy excitation during the expansion and compression phases. The total energy is determined by the work done over a complete cycle. Utilizing Fourier’s law for heat conduction, we have determined that the power output is explicitly influenced by the duration of the heating and cooling strokes as well as the engine’s efficiency. Specifically, a longer stroke time and higher efficiency result in reduced power output. To calculate EMP, we optimize power by varying the compression ratio (κ), and we have found that EMP is also influenced by the isochoric heating and cooling processes. When varying the duration of the isochoric process, EMP shows a slight decrease as isochoric time increases due to entropy production. However, significant improvements in the EMP of the Otto Engine can be achieved by extending the cooling stroke time beyond the heating stroke time.