An analytical study of the endoreversible Curzon–Ahlborn cycle for a non-linear heat transfer law

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This paper presents a finite-time thermodynamic optimization based on three different optimization criteria: Maximum Power Output (MP), Maximum Efficient Power (MEP), and Maximum Power Density (MPD), for a simplified Curzon-Ahlborn engine that was first proposed by Agrawal. The results obtained for the MP are compared with those obtained using MEP and MPD criteria. The results show that when a Newton heat transfer law is used, the efficiency values of the engine working in the MP regime are lower than the efficiency values ( τ ) obtained with the MEP and MPD regimes for all values of the parameter τ = T 2 / T 1 , where T 1 and T 2 are the hot and cold temperatures of the engine reservoirs ( T 2 < T 1 ) , respectively. However, when a Dulong-Petit heat transfer law is used, the efficiency values of the engine working at MEP are larger than those obtained with the MP and the MPD regimes for all values of τ . Notably, when 0 < τ < 0.68 , the efficiency values for the MP regime are larger than those obtained with the MPD regime. Also, when 0.68 < τ < 1 , the efficiency values for the aforementioned regimes are similar. Importantly, the parameter τ plays a crucial role in the engine performance, providing guidance during the design of real power plants.

Section: Modeling Methods and Resultssupporting

confidence: 78%

“…In accordance with the procedure followed by Agrawal [ 20 ] and repeated by Páez-Hernández et al [ 21 ], the power output can be written as:

…”

Section: Modeling Methods and Resultsmentioning

confidence: 99%

“…Following the same procedure performed by Páez-Hernández et al [ 21 ], we analyzed the engine shown in Figure 1 , but considering a Dulong-Petit heat transfer law, whichis

, where

is the thermal conductance and

is the exponent related to natural convection [ 23 ], with

at the hot isotherm and

at the cold isotherm of the cycle.…”

Section: Modeling Methods and Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Comparative Performance Analysis of a Simplified Curzon-Ahlborn Engine

Páez-Hernández

Chimal-Eguía

Ladino-Luna

et al. 2018

Self Cite

“…Of particular interest are efficiency considerations. From the seminal work of Curzon and Ahlborn [ 20 ], to recent publications concerning non-linear irreversible systems [ 21 , 22 , 23 , 24 ], stochastic fluctuations [ 25 , 26 , 27 ], thermoelectric generators [ 28 ], biological processes [ 29 ] or general realizability domains [ 30 ] a multitude of investigations were carried out.…”

Section: Introductionmentioning

confidence: 99%

Optimized Piston Motion for an Alpha-Type Stirling Engine

Masser

Khodja

Scheunert

et al. 2020

The Stirling engine is one of the most promising devices for the recovery of waste heat. Its power output can be optimized by several means, in particular by an optimized piston motion. Here, we investigate its potential performance improvements in the presence of dissipative processes. In order to ensure the possibility of a technical implementation and the simplicity of the optimization, we restrict the possible piston movements to a parametrized class of smooth piston motions. In this theoretical study the engine model is based on endoreversible thermodynamics, which allows us to incorporate non-equilibrium heat and mass transfer as well as the friction of the piston motion. The regenerator of the Stirling engine is modeled as ideal. An investigation of the impact of the individual loss mechanisms on the resulting optimized motion is carried out for a wide range of parameter values. We find that an optimization within our restricted piston motion class leads to a power gain of about 50% on average.

“…It is part of the Finite Time Thermodynamics and makes the modelling assumption that all systems can be subdivided into reversible subsystems and, potentially irreversible, interactions between these subsystems. Endoreversible models have been used in the past decades to investigate a large variety of systems [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ] with ongoing research in this field [ 24 , 25 , 26 , 27 , 28 , 29 ]. One of the advantages of Endoreversible Thermodynamics is its ability to model also transient phenomena in thermal processes [ 6 ].…”

Section: Introductionmentioning

confidence: 99%

Performance Features of a Stationary Stochastic Novikov Engine

Schwalbe

Hoffmann

2018

Abstract:In this article a Novikov engine with fluctuating hot heat bath temperature is presented. Based on this model, the performance measure maximum expected power as well as the corresponding efficiency and entropy production rate is investigated for four different stationary distributions: continuous uniform, normal, triangle, quadratic, and Pareto. It is found that the performance measures increase monotonously with increasing expectation value and increasing standard deviation of the distributions. Additionally, we show that the distribution has only little influence on the performance measures for small standard deviations. For larger values of the standard deviation, the performance measures in the case of the Pareto distribution are significantly different compared to the other distributions. These observations are explained by a comparison of the Taylor expansions in terms of the distributions' standard deviations. For the considered symmetric distributions, an extension of the well known Curzon-Ahlborn efficiency to a stochastic Novikov engine is given.