A Second-Law Analysis of Air-Standard Diesel—Turbocharger–Bottoming Cycles

1993 ◽  
Vol 207 (2) ◽  
pp. 107-114 ◽  
Author(s):  
J B Woodward
Keyword(s):  
Mechanical Engineering ◽  
Constant Pressure ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Numerical Examples ◽  
Power Cycle ◽  
Second Law Analysis ◽  
Diesel Cycle

It is asserted that some of the mechanical engineering literature on power cycle analysis does not make sufficient use of the second law of thermodynamics. Advantages of second-law use are listed and then demonstrated through development by equations by which analysis of an air-standard diesel cycle can incorporate constant-pressure turbocharging and a Rankine bottoming cycle. Steps towards application to real machinery are also demonstrated. Four numerical examples are included.

Analysis of Throttle Opening Variation Impact on a Diesel Engine Performance Using Second Law of Thermodynamics

2009 ◽  
Author(s):  
B. B. Sahoo ◽  
U. K. Saha ◽  
N. Sahoo ◽  
P. Prusty
Keyword(s):  
Diesel Engine ◽  
Direct Injection ◽  
Fuel Efficiency ◽  
Engine Performance ◽  
Second Law Of Thermodynamics ◽  
Operating Conditions ◽  
Second Law ◽  
Engine Fuel ◽  
Availability Analysis ◽  
Second Law Analysis

The fuel efficiency of a modern diesel engine has decreased due to the recent revisions to emission standards. For an engine fuel economy, the engine speed is to be optimum for an exact throttle opening (TO) position. This work presents an analysis of throttle opening variation impact on a multi-cylinder, direct injection diesel engine with the aid of Second Law of thermodynamics. For this purpose, the engine is run for different throttle openings with several load and speed variations. At a steady engine loading condition, variation in the throttle openings has resulted in different engine speeds. The Second Law analysis, also called ‘Exergy’ analysis, is performed for these different engine speeds at their throttle positions. The Second Law analysis includes brake work, coolant heat transfer, exhaust losses, exergy efficiency, and airfuel ratio. The availability analysis is performed for 70%, 80%, and 90% loads of engine maximum power condition with 50%, 75%, and 100% TO variations. The data are recorded using a computerized engine test unit. Results indicate that the optimum engine operating conditions for 70%, 80% and 90% engine loads are 2000 rpm at 50% TO, 2300 rpm at 75% TO and 3250 rpm at 100% TO respectively.

Efficiency of ideal fuel cell and Carnot cycle from a fundamental perspective

2005 ◽  
Vol 219 (4) ◽  
pp. 245-254 ◽  
Author(s):  
H Hassanzadeh ◽  
S H Mansouri
Keyword(s):  
Fuel Cell ◽  
Heat Engine ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Carnot Cycle ◽  
Combustion Engines ◽  
Numerical Examples ◽  
Cell Efficiency ◽  
Electrochemical Systems ◽  
Heat Engines

In this paper, we accept the fact that fuel cell and heat engine efficiencies are both constrained by the second law of thermodynamics and neither one is able to break this law. However, we have shown that this statement does not mean the two systems should have the same maximum thermal efficiency when being fed by the same amounts of chemical reactants. The intrinsic difference between fuel cells (electrochemical systems) and heat engines (combustion engines) efficiencies is a fundamental one with regard to the conversion of chemical energy of reactions into electrical work. The sole reason has been shown to be due to the combustion irreversibility of the latter. This has led to the statement that fuel cell efficiency is not limited by the Carnot cycle. Clarity is achieved by theoretical derivations and several numerical examples.

Second Law Analysis and Synthesis of Solar Collector Systems

1981 ◽  
Vol 103 (1) ◽  
pp. 23-28 ◽  
Author(s):  
A. Bejan ◽  
D. W. Kearney ◽  
F. Kreith
Keyword(s):  
Heat Transfer ◽  
Solar Collector ◽  
Second Law Of Thermodynamics ◽  
Ambient Air ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Second Law ◽  
Second Law Analysis ◽  
Analysis And Synthesis ◽  
Minimum Heat

The second law of thermodynamics is used to analyze the potential for exergy conservation in solar collector systems. It is shown that the amount of useful energy (exergy) delivered by solar collector systems is affected by heat transfer irreversibilities occurring between the sun and the collector, between the collector and the ambient air, and inside the collector. Using as working examples an isothermal collector, a nonisothermal collector, and the design of the collector-user heat exchanger, the optimum operating conditions for minimum heat transfer irreversibility (maximum exergy delivery) are derived.

scholarly journals Thermodynamical motivation of the Polish energy policy

2011 ◽  
Vol 33 (4) ◽  
pp. 3-21 ◽  
Author(s):  
Andrzej Ziębik
Keyword(s):  
Energy Policy ◽  
High Efficiency ◽  
Second Law Of Thermodynamics ◽  
Primary Energy ◽  
Point Of View ◽  
Second Law ◽  
Special Importance ◽  
Second Law Analysis ◽  
Transmission And Distribution ◽  
Exergy Losses

Abstract Basing on the first and second law of thermodynamics the fundamental trends in the Polish energy policy are analysed, including the aspects of environmental protection. The thermodynamical improvement of real processes (reduction of exergy losses) is the main way leading to an improvement of the effectivity of energy consumption. If the exergy loss is economically not justified, we have to do with an error from the viewpoint of the second law analysis. The paper contains a thermodynamical analysis of the ratio of final and primary energy, as well as the analysis of the thermo-ecological cost and index of sustainable development concerning primary energy. Analyses of thermo-ecological costs concerning electricity and centralized heat production have been also carried out. The effect of increasing the share of high-efficiency cogeneration has been analyzed, too. Attention has been paid to an improved efficiency of the transmission and distribution of electricity, which is of special importance from the viewpoint of the second law analysis. The improvement of the energy effectivity in industry was analyzed on the example of physical recuperation, being of special importance from the point of view of exergy analysis.

A Second-Law Analysis of Thermoelastic Damping

1994 ◽  
Vol 61 (1) ◽  
pp. 71-76 ◽  
Author(s):  
V. K. Kinra ◽  
K. B. Milligan
Keyword(s):  
Stress Field ◽  
Heterogeneous Material ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Homogeneous Material ◽  
Thermoelastic Damping ◽  
Temperature Changes ◽  
Starting Point ◽  
Second Law Analysis ◽  
Thermoelastic Solid

In accordance with the Thomson effect (Thomson, 1853), when a thermoelastic solid is subjected to a tensile stress, it cools. Similarly, when a homogeneous material is subjected to an inhomogeneous stress field or when an heterogeneous material is subjected to any stress field (homogeneous or inhomogeneous), different parts of the material undergo different temperature changes. As a result irreversible heat conduction occurs and entropy is produced. In this paper we take the second law of thermodynamics as our starting point and develop a general theory for calculating the thermoelastic damping from the entropy produced.

Derivation of Entropy and Exergy Transport Equations, and Application to Second Law Analysis of Sugarcane Bagasse Gasification in Bubbling Fluidized Beds

2019 ◽  
Vol 142 (6) ◽  
Author(s):  
Gabriel L. Verissimo ◽  
Manuel E. Cruz ◽  
Albino J. K. Leiroz
Keyword(s):  
Sugarcane Bagasse ◽  
Fluidized Beds ◽  
Chemical Species ◽  
Second Law Of Thermodynamics ◽  
Transport Equations ◽  
Second Law ◽  
Exergy Destruction ◽  
Gasification Process ◽  
Second Law Analysis ◽  
Biomass Particles

Abstract In the present work, the transport equations for mass, momentum, energy, and chemical species as given by the Euler–Euler formulation for multiphase flows are used together with the second law of thermodynamics to derive the entropy and exergy transport equations, suitable to the study of gas-particle reactive flows, such as those observed during pyrolysis, gasification, and combustion of biomass particles. The terms of the derived equations are discussed, and the exergy destruction contributions are identified. Subsequently, a kinetic model is implemented in a computational fluid dynamics (CFD) open source code for the sugarcane bagasse gasification. Then, the derived exergy destruction terms are implemented numerically through user-defined Fortran routines. Next, the second law analysis of the gasification process of sugarcane bagasse in bubbling fluidized beds is carried out. Detailed results are obtained for the local destructions of exergy along the reactor. This information is important to help improve environmental and sustainable practices and should be of interest to both designers and operators of fluidized bed equipment.

Energy and heat

2017 ◽  
Author(s):  
Andrew Clarke
Keyword(s):  
Thermal Equilibrium ◽  
Growth And Development ◽  
Constant Pressure ◽  
Open Systems ◽  
Second Law Of Thermodynamics ◽  
Ideal Gas ◽  
Second Law ◽  
Total Entropy ◽  
Isothermal Conditions ◽  
System P

Energy is the capacity to do work and heat is the spontaneous flow of energy from one body or system to another through the random movement of atoms or molecules. The entropy of a system determines how much of its internal energy is unavailable for work under isothermal conditions, and the Gibbs energy is the energy available for work under isothermal conditions and constant pressure. The Second Law of Thermodynamics states that for any reaction to proceed spontaneously the total entropy (system plus surroundings) must increase, which is why metabolic processes release heat. All organisms are thermodynamically open systems, exchanging both energy and matter with their surroundings. They can decrease their entropy in growth and development by ensuring a greater increase in the entropy of the environment. For an ideal gas in thermal equilibrium the distribution of energy across the component atoms or molecules is described by the Maxwell-Boltzmann equation. This distribution is fixed by the temperature of the system.

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