Efficiency Enhancement on Hybrid Power System Composed of Irreversible Solid Oxide Fuel Cell and Stirling Engine by Finite Time Thermodynamics

This paper presents the work for efficiency enhancement on a hybrid power system with an irreversible Solid Oxide Fuel Cell (SOFC) and Stirling Engine (SE) for various system design using the approach of finite-time thermodynamics. The SOFC-based cogeneration system was integrated with an SE and several heat components. The effects of design configurations using various interface components on system performance were investigated. By analyzing the SE with finite-time thermodynamics and considering multiple irreversible factors of output power given by the SOFC, the efficiency of the calculation can be more practical and accurate. In this study, the working efficiency of the proposed hybrid system was enhanced by 16.37% compared to that of the conventional system at an intermediate temperature of 873 K. The design approach proposed herein is considered an essential package for building highly efficient power systems working in the intermediate temperature range.

Quantum Finite-Time Thermodynamics: Insight from a Single Qubit Engine

Incorporating time into thermodynamics allows for addressing the tradeoff between efficiency and power. A qubit engine serves as a toy model in order to study this tradeoff from first principles, based on the quantum theory of open systems. We study the quantum origin of irreversibility, originating from heat transport, quantum friction, and thermalization in the presence of external driving. We construct various finite-time engine cycles that are based on the Otto and Carnot templates. Our analysis highlights the role of coherence and the quantum origin of entropy production.

Thermoelectric Efficiency of Silicon–Germanium Alloys in Finite-Time Thermodynamics

We analyze the efficiency in terms of a thermoelectric system of a one-dimensional Silicon–Germanium alloy. The dependency of thermal conductivity on the stoichiometry is pointed out, and the best fit of the experimental data is determined by a nonlinear regression method (NLRM). The thermoelectric efficiency of that system as function of the composition and of the effective temperature gradient is calculated as well. For three different temperatures (T=300 K, T=400 K, T=500 K), we determine the values of composition and thermal conductivity corresponding to the optimal thermoelectric energy conversion. The relationship of our approach with Finite-Time Thermodynamics is pointed out.