A heat engine model of a reversible computation

1990 ◽  
Vol 78 (5) ◽  
pp. 817-825 ◽  
Author(s):  
D.G. Jablonski
Keyword(s):  
Heat Engine ◽  
Reversible Computation ◽  
Engine Model

The Role of Internal Irreversibilities in the Performance and Stability of Power Plant Models Working at Maximum ϵ-Ecological Function

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Gabriel Valencia-Ortega ◽  
Sergio Levario-Medina ◽  
Marco Antonio Barranco-Jiménez
Keyword(s):  
Power Plants ◽  
Heat Engine ◽  
Combined Cycle ◽  
Ecological Function ◽  
Operating Conditions ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Engine Model ◽  
Improved Stability ◽  
The Stability

Abstract The proposal of models that account for the irreversibilities within the core engine has been the topic of interest to quantify the useful energy available during its conversion. In this work, we analyze the energetic optimization and stability (local and global) of three power plants, nuclear, combined-cycle, and simple-cycle ones, by means of the Curzon–Ahlborn heat engine model which considers a linear heat transfer law. The internal irreversibilities of the working fluid measured through the r-parameter are associated with the so-called “uncompensated Clausius heat.” In addition, the generalization of the ecological function is used to find operating conditions in three different zones, which allows to carry out a numerical analysis focused on the stability of power plants in each operation zone. We noted that not all power plants reveal stability in all the operation zones when irreversibilities are considered through the r-parameter on real-world power plants. However, an improved stability is shown in the zone limited by the maximum power output and maximum efficiency regimes.

Analysis on the Performance of a Thermoelectric Generator

1999 ◽  
Vol 122 (2) ◽  
pp. 61-63 ◽  
Author(s):  
Jincan Chen ◽  
Chih Wu
Keyword(s):  
Power Output ◽  
Physical Meaning ◽  
Design Parameter ◽  
Thermoelectric Generator ◽  
Heat Engine ◽  
Simple Expression ◽  
Maximum Efficiency ◽  
Thermoelectric Generators ◽  
Optimal Range ◽  
Engine Model

An externally and internally irreversible heat engine model of thermoelectric generators is used to analyze the so-called device-design parameter introduced by O¨zkaynak et al. The simple expression of the parameter is given and its physical meaning is expounded. Moreover, the optimal range of the parameter is determined and the problems relative to the maximum power output and maximum efficiency are discussed. Some meaningful results are obtained. [S0195-0738(00)00401-5]

scholarly journals Inertial Waves in Axisymmetric Tropical Cyclones

2020 ◽  
Vol 77 (7) ◽  
pp. 2501-2517
Author(s):  
Morgan E O’Neill ◽  
Daniel R. Chavas
Keyword(s):  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
Heat Engine ◽  
Lateral Spread ◽  
Radiative Cooling ◽  
Engine Model ◽  
Storm Dynamics ◽  
Outflow Region ◽  
Inertial Wave ◽  
The Impact

AbstractThe heat engine model of tropical cyclones describes a thermally direct overturning circulation. Outflowing air slowly subsides as radiative cooling to space balances adiabatic warming, a process that does not consume any work. However, we show here that the lateral spread of the outflow is limited by the environmental deformation radius, which at high latitudes can be rather small. In such cases, the outflowing air is radially constrained, which limits how far downward it can subside via radiative cooling alone. Some literature has invoked the possibility of “mechanical subsidence” or “forced descent” in the storm outflow region in the presence of high inertial stability, which would be a thermally indirect circulation. Mechanical subsidence in the subsiding branch of a tropical cyclone has not before been observed or characterized. A series of axisymmetric tropical cyclone simulations at different latitudes and domain sizes is conducted to study the impact of environmental inertial stability on storm dynamics. In higher-latitude storms in large axisymmetric domains, the outflow acts as a wavemaker to excite an inertial wave at the environmental inertial (Coriolis) frequency. This inertial wave periodically ventilates the core of a high-latitude storm with its own low-entropy exhaust air. The wave response is in contrast to the presumed forced descent model, and we hypothesize that this is because inertial stability provides less resistance than buoyant stability, even in highly inertially stable environments.

A scaling study of a combined microcombustor and heat engine system

2005 ◽  
Vol 219 (5) ◽  
pp. 371-381 ◽  
Author(s):  
R. B. Peterson
Keyword(s):  
Heat Recovery ◽  
Heat Engine ◽  
System Efficiency ◽  
Thermal Loss ◽  
Engine Model ◽  
Ideal System ◽  
Exhaust Stream ◽  
Power Point ◽  
High Degree ◽  
Loss Mechanisms

A general heat engine model is developed for determining the scaling characteristics of small combustion-driven energy systems. The model is composed of a Carnot heat engine and a combustor operating at a specified temperature dictated by the thermodynamic maximum power point. Considerations have been made for thermal conduction losses to the surroundings and heat recovery from the exhaust stream of the combustor. Modelling of the conduction heat loss is necessary due to the increased importance of this effect upon a reduction in size. This model is used to determine the ideal system efficiency as a function of characteristic length. This length is then varied from mesoscale dimensions to the microscale with the overall system efficiency being determined at each point. The scaling study provides a sense for the ultimate size limitations imposed on combustion-driven engines due to thermal loss mechanisms to the surroundings. Although a high degree of idealization is employed, this analysis shows that submillimetre engine/combustor systems appear impractical, but characteristic sizes in the range of a few millimetres are feasible, at least in regards to the thermal loss mechanisms. This study also shows that systems having a conduction parameter greater than approximately 0.5 do not benefit significantly from heat exchanger NTU values greater than 3 due to the diminishing benefits of heat recovery with larger conduction losses.

scholarly journals Finite-Time Thermoeconomic Optimization of a Solar-Driven Heat Engine Model

Entropy ◽  
2011 ◽  
Vol 13 (1) ◽  
pp. 171-183 ◽  
Author(s):  
Marco A. Barranco-Jimenez ◽  
Norma Sanchez-Salas ◽  
Fernando Angulo-Brown
Keyword(s):  
Finite Time ◽  
Heat Engine ◽  
Engine Model

scholarly journals Energetic Optimization Considering a Generalization of the Ecological Criterion in Traditional Simple-Cycle and Combined-Cycle Power Plants

2020 ◽  
Vol 45 (3) ◽  
pp. 269-290 ◽  
Author(s):  
Sergio Levario-Medina ◽  
Gabriel Valencia-Ortega ◽  
Marco Antonio Barranco-Jiménez
Keyword(s):  
Power Plants ◽  
Heat Engine ◽  
Combined Cycle ◽  
Maximum Efficiency ◽  
Type Model ◽  
Model Parameters ◽  
Energy Converter ◽  
Engine Model ◽  
Optimal Region ◽  
Energetic Performance

AbstractThe fundamental issue in the energetic performance of power plants, working both as traditional fuel engines and as combined-cycle turbines (gas-steam), lies in quantifying the internal irreversibilities which are associated with the working substance operating in cycles. The purpose of several irreversible energy converter models is to find objective thermodynamic functions that determine operation modes for real thermal engines and at the same time study the trade-off between energy losses per cycle and the useful energy. As those objective functions, we focus our attention on a generalization of the so-called ecological function in terms of an ϵ parameter that depends on the particular heat transfer law used in the irreversible heat engine model. In this work, we mathematically describe the configuration space of an irreversible Curzon–Ahlborn type model. The above allows to determine the optimal relations between the model parameters so that a power plant operates in physically accessible regions, taking into account internal irreversibilities, introduced in two different ways (additively and multiplicatively). In addition, we establish the conditions that the ϵ parameter must fulfill for the energy converter to work in an optimal region between maximum power output and maximum efficiency points.

scholarly journals Thermolytic reverse electrodialysis heat engine: model development, integration and performance analysis

2019 ◽  
Vol 189 ◽  
pp. 1-13 ◽  
Author(s):  
F. Giacalone ◽  
F. Vassallo ◽  
L. Griffin ◽  
M.C. Ferrari ◽  
G. Micale ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Model Development ◽  
Heat Engine ◽  
Reverse Electrodialysis ◽  
Engine Model ◽  
And Performance

A Novel Approach to the Teaching of Etropy Based on a Recent Single Particle Heat Engine Model

2006 ◽  
Author(s):  
W. John Dartnall ◽  
John Reizes
Keyword(s):  
Single Particle ◽  
Heat Engine ◽  
Working Fluid ◽  
Second Law ◽  
Piston Engine ◽  
New Approach ◽  
Engine Model ◽  
Mechanics Model ◽  
Heat Engines ◽  
Novel Approach

In a recently developed simple particle mechanics model in which a single particle represents the working fluid (gas) in a heat engine (exemplified by a piston engine) a new approach was outlined for the teaching of concepts to thermodynamic students. By mechanics reasoning a model was developed that demonstrates the connection between the Carnot efficiency limitation of heat engines and the Kelvin-Planck statement of Second Law requiring only the truth of the Clausius statement. In this paper the model is extended to introduce entropy. Here the particle's entropy is defined as a function of its kinetic energy and the space that it occupies that is analogous to that normally found in classical macroscopic analyses.

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