Power-Optimal Control of a Stirling Engine’s Frictional Piston Motion

Abstract

The power output of Stirling engines can be optimized by several means. In this study, the focus is on potential performance improvements that can be achieved by optimizing the piston motion of an alpha-Stirling engine in the presence of dissipative processes, in particular mechanical friction. We use a low-effort endoreversible Stirling engine model, which allows for the incorporation of finite heat and mass transfer as well as the friction caused by the piston motion. Instead of performing a parameterization of the piston motion and optimizing these parameters, we here use an indirect iterative gradient method that is based on Pontryagin’s maximum principle. For the varying friction coefficient, the optimization results are compared to both, a harmonic piston motion and optimization results found in a previous study, where a parameterized piston motion had been used. Thus we show how much performance can be improved by using the more sophisticated and numerically more expensive iterative gradient method.

Four-Objective Optimization for an Irreversible Porous Medium Cycle with Linear Variation in Working Fluid’s Specific Heat

“…Finite time thermodynamics (FTT) [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ] has been made significant progress in the research of thermal cycles and processes, including optimal configurations [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ] and optimal performances [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. The FTT studies of internal combustion engine cycles mostly focus on the following factors [ 33 ]: the effects of different loss models such as heat transfer loss (HTL) [ 34 ], friction loss (FL) [ 35 ] and internal irreversibility loss (IIL) [ 36 ] on the performances of cycles; the effects of power output ( ) and thermal efficiency ( ) [ 37 ], efficient power ( ) [ 38 ], ecological function ( ) [ 39 ], power density ( ) [ 40 ] and other ob...…”

Finite-Time Thermodynamic Modeling and Analysis of Seawater Acidification Process in Electrochemical Acidification Cell

“…Ni et al [ 19 , 20 ] established the electrochemical models of the solid oxide steam electrolysis cell and investigated the influences of parameters on the energy and exergy efficiency of the process. Finite-time thermodynamics (FTT) [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ] have been applied for modeling and performance optimizations of various thermodynamic, chemical, and economic processes, devices, and cycles since 1975. Sieniutycz et al [ 31 , 32 , 33 , 34 , 35 ] established the physical model of the unsteady state of the multistage electrochemical systems of fuel cells, and analyzed the influence of irreversible losses on the performance of the cell.…”