Can a quantitative simulation of an Otto engine be accurately rendered by a simple Novikov model with heat leak?

139

Abstract:On the basis of introducing the origin and development of finite time thermodynamics (FTT), this paper reviews the progress in FTT optimization for internal combustion engine (ICE) cycles from the following four aspects: the studies on the optimum performances of air standard endoreversible (with only the irreversibility of heat resistance) and irreversible ICE cycles, including Otto, Diesel, Atkinson, Brayton, Dual, Miller, Porous Medium and Universal cycles with constant specific heats, variable specific heats, and variable specific ratio of the conventional and quantum working fluids (WFs); the studies on the optimum piston motion (OPM) trajectories of ICE cycles, including Otto and Diesel cycles with Newtonian and other heat transfer laws; the studies on the performance limits of ICE cycles with non-uniform WF with Newtonian and other heat transfer laws; as well as the studies on the performance simulation of ICE cycles. In the studies, the optimization objectives include work, power, power density, efficiency, entropy generation rate, ecological function, and so on. The further direction for the studies is explored.

Section: The Progress In Optimum Performance Studies For As Otto Cyclesmentioning

confidence: 99%

Progress in Finite Time Thermodynamic Studies for Internal Combustion Engine Cycles

Chen

Sun

2016

139

“…It was obtained by considering both P and η as fluctuating functions of the fuel ratio, φ, taken as a parametric variable. This figure is the probabilistic counterpart of the power-efficiency loop-shaped curves that are usual in thermodynamic optimization for both internal [18,26,31,35,36] and external combustion [37][38][39][40] models. These curves, which constitute a powerful optimization tool in the field of thermodynamic optimization, have the shape of a closed loop (such as the contour of a mussel), with different values for maximum power and maximum efficiency points.…”

Section: Correlations Between Heat Release and Performance Output Funmentioning

confidence: 99%

Fluctuations in the Energetic Properties of a Spark-Ignition Engine Model with Variability

Curto-Risso

Medina

Hernández

et al. 2013

We study the energetic functions obtained in a simulated spark-ignited engine that incorporates cyclic variability through a quasi-dimensional combustion model. Our analyses are focused on the effects of the fuel-air equivalence ratio of the mixture simultaneously over the cycle-to-cycle fluctuations of heat release (Q R ) and the performance outputs, such as the power (P ) and the efficiency (η). We explore the fluctuant behavior for Q R , P and η related to random variations of the basic physical parameters in an entrainment or eddy-burning combustion model. P and η show triangle shaped first return maps, while Q R exhibits a structured map, especially at intermediated fuel-air ratios. Structure disappears to a considerable extent in the case of heat release and close-to-stoichiometry fuel-air ratios. By analyzing the fractal dimension to explore the presence of correlations at different scales, we find that whereas Q R displays short-range correlations for intermediate values of the fuel ratio, both P and η are characterized by a single scaling exponent, denoting irregular fluctuations. A novel noisy loop-shaped P vs. η plot for a large number of engine cycles Entropy 2013, 15 3278 is obtained. This plot, which evidences different levels of irreversibilities as the fuel ratio changes, becomes the observed loop P vs. η curve when fluctuations are disregarded, and thus, only the mean values for efficiency and power are considered.

“…Within the context of FTT, it has been possible to elaborate detailed models of heat engines working at finite-time and with entropy production [6][7][8][9][10]. One of the applications of FTT has been in the field of thermoeconomics [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Thermoeconomic Optimization of an Irreversible Novikov Plant Model under Different Regimes of Performance

Pacheco-Paez

Angulo‐Brown

Barranco-Jiménez

2017

Abstract:The so-called Novikov power plant model has been widely used to represent some actual power plants, such as nuclear electric power generators. In the present work, a thermo-economic study of a Novikov power plant model is presented under three different regimes of performance: maximum power (MP), maximum ecological function (ME) and maximum efficient power (EP). In this study, different heat transfer laws are used: The Newton's law of cooling, the Stefan-Boltzmann radiation law, the Dulong-Petit's law and another phenomenological heat transfer law. For the thermoeconomic optimization of power plant models, a benefit function defined as the quotient of an objective function and the total economical costs is commonly employed. Usually, the total costs take into account two contributions: a cost related to the investment and another stemming from the fuel consumption. In this work, a new cost associated to the maintenance of the power plant is also considered. With these new total costs, it is shown that under the maximum ecological function regime the plant improves its economic and energetic performance in comparison with the other two regimes. The methodology used in this paper is within the context of finite-time thermodynamics.