Optimal path of piston motion of irreversible Otto cycle for minimum entropy generation with radiative heat transfer law

Convective heat transfer enhancement can significantly improve the thermal efficiency in the conversion, utilization, recovery and storage of energy (in particular solar thermal). Modifying velocity field is the most direct approach to enhance convective heat transfer. However, in most cases the optimal velocity field is unknown and difficult to find even for an experienced researcher. In this paper, a predictive optimization methodology in convective heat transfer enhancement based on minimum entropy generation (MEG) principle was developed. A set of Euler’s equations were derived by the variation calculus to the Lagrange function established by governing equations, specific constraints and objective functional—total entropy generation rate. The solution of these equations resulted in the optimal velocity fields, leading to the minimum entropy generation. To validate and demonstrate the future application of this methodology to solar absorbers used to convert concentrated solar energy, the steady laminar convection heat transfer process in a two-dimensional channel with fixed heat flux boundaries was optimized for given total viscous dissipations. The numerical simulation results showed that lower value of maximum wall temperature was obtained by MEG optimization, which means cheaper and safer materials. The present work indicated that the new methodology could be a good guide in convective heat transfer enhancement design work, especially in CSP receivers.

Download Full-text

“Entransy,” and Its Lack of Content in Physics

Journal of Heat Transfer ◽

10.1115/1.4026527 ◽

2014 ◽

Vol 136 (5) ◽

Cited By ~ 49

Author(s):

Adrian Bejan

Keyword(s):

Heat Transfer ◽

Thermal Resistance ◽

Entropy Generation ◽

Solid Body ◽

Thermodynamic Temperature ◽

Entransy Dissipation ◽

Minimum Entropy ◽

Constructal Law ◽

Minimum Entropy Generation ◽

False Claim

Here, I show that “entransy” has no meaning in physics, because, at bottom, it rests on the false claim that in order to transfer heat to a solid body of thermodynamic temperature T, the heat transfer must be proportional to T. Entransy “dissipation” is a number proportional to well known measures of irreversibility such as entropy generation and lost exergy (destroyed available work). Furthermore, the “principle of entransy dissipation minimization” adds nothing to existing work based on minimum entropy generation, minimum thermal resistance, and constructal law. The broader trend illustrated by the entransy hoax is that it is becoming easy to take an existing idea, change the keywords, and publish it as new.

Download Full-text

Optimal paths of piston motion of irreversible diesel cycle for minimum entropy generation

Thermal Science ◽

10.2298/tsci110720100g ◽

2011 ◽

Vol 15 (4) ◽

pp. 975-993 ◽

Cited By ~ 9

Author(s):

Yanlin Ge ◽

Lingen Chen ◽

Fengrui Sun

Keyword(s):

Entropy Generation ◽

Minimum Entropy ◽

Piston Motion ◽

Optimal Paths ◽

Diesel Cycle ◽

Minimum Entropy Generation

Download Full-text

Genetic Algorithm-Based Optimal Design of Plate Fins Following Minimum Entropy Generation Considerations

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/095440605x31544 ◽

2005 ◽

Vol 219 (8) ◽

pp. 757-765 ◽

Cited By ~ 5

Author(s):

R. K. Jha ◽

S Chakraborty

Keyword(s):

Heat Transfer ◽

Genetic Algorithm ◽

Optimal Design ◽

Forced Convection ◽

Entropy Generation ◽

Generation Rate ◽

Entropy Generation Rate ◽

Minimum Entropy ◽

Minimum Entropy Generation ◽

Continuous Plate

This paper deals with estimation of the optimal dimensions of arrays of plate fins cooled by forced convection. The optimization is achieved by minimizing the entropy generation rate using genetic algorithm-based evolutionary computing techniques. Results are presented for staggered plate fins configuration and continuous plate fins configuration. The effects of heat transfer and fluid friction on entropy generation rate are also reported.

Download Full-text

The Equivalence of Maximum Power and Minimum Entropy Generation Rate in the Optimization of Power Plants

Journal of Energy Resources Technology ◽

10.1115/1.2792711 ◽

1996 ◽

Vol 118 (2) ◽

pp. 98-101 ◽

Cited By ~ 18

Author(s):

Adrian Bejan

Keyword(s):

Heat Transfer ◽

Power Plant ◽

Entropy Generation ◽

Heat Input ◽

Power Plants ◽

Generation Rate ◽

Entropy Generation Rate ◽

Total Entropy ◽

Minimum Entropy ◽

Minimum Entropy Generation

It is shown that to maximize the power output of a power plant is equivalent to minimizing the total entropy generation rate associated with the power plant. This equivalence is illustrated by using two of the oldest and simplest models of power plants with heat transfer irreversibilities. To calculate the total entropy generation rate correctly, one must recognize that the optimization process (e.g., the variability of the heat input) requires “room to move,” i.e., an additional, usually overlooked, contribution to the total entropy generation rate.

Download Full-text