Thermodynamic Analysis of a Multi-Fueled Single Cylinder SI Engine

2011 ◽  
Author(s):  
M. Z. Haq ◽  
M. R. Mohiuddin
Keyword(s):  
Thermodynamic Analysis ◽  
Chemical Properties ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Si Engine ◽  
Gaseous Species ◽  
Single Cylinder ◽  
Engine Cylinder ◽  
Si Engines

The paper presents a thermodynamic analysis of a single cylinder four-stroke spark-ignition (SI) engine fuelled by four fuels namely iso-octane, methane, methanol and hydrogen. In SI engines, due to phenomena like ignition delay and finite flame speed manifested by the fuels, the heat addition process is not instantaneous, and hence ‘Weibe function’ is used to address the realistic heat release scenario of the engine. Empirical correlations are used to predict the heat loss from the engine cylinder. Physical states and chemical properties of gaseous species present inside the cylinder are determined using first and second law of thermodynamics, chemical kinetics, JANAF thermodynamic data-base and NASA polynomials. The model is implemented in FORTRAN 95 using standard numerical routines and some simulation results are validated against data available in literature. The second law of thermodynamics is applied to estimate the change of exergy i.e. the work potential or quality of the in-cylinder mixture undergoing various phases to complete the cycle. Results indicate that, around 4 to 24% of exergy initially possessed by the in-cylinder mixture is reduced during combustion and about 26 to 42% is left unused and exhausted to the atmosphere.

Thermodynamic Analysis of the CO2 Gas Removal Process

2007 ◽  
Author(s):  
Rosa-Hilda Chavez ◽  
Jazmin Cortez-Gonzalez ◽  
Javier de J. Guadarrama ◽  
Abel Hernandez-Guerrero
Keyword(s):  
Thermodynamic Analysis ◽  
Second Law Of Thermodynamics ◽  
Chemical Processes ◽  
Second Law ◽  
Equilibrium Partial Pressure ◽  
Co2 Gas ◽  
Acid Gas ◽  
Removal Process ◽  
Gas Removal ◽  
Carbon Dioxide Co2

The present paper describes the thermodynamic analysis of the carbon dioxide (CO2) gas removal process in two separated columns with absorption/stripping sections respectively. This process is characterized as mass transfer enhanced by chemical reaction, in which the presence of an alkanolamine enhances the solubility of an acid gas in the aqueous phase at a constant value of the equilibrium partial pressure. A very useful procedure for analyzing a process is by means of the Second Law of Thermodynamics. Thermodynamic analyses based on the concepts of irreversible entropy increase have frequently been suggested as pointers to sources of inefficiency in chemical processes. Furthermore, they point out where the irreversibilities of the process are located, and provide a generalized discussion from the successful application of the technique.

A Micro Combined Heat and Power Thermodynamic Analysis and Optimization

2010 ◽  
Author(s):  
Ali Gholizadeh ◽  
M. B. Shafii ◽  
M. H. Saidi
Keyword(s):  
Combustion Chamber ◽  
Entropy Production ◽  
Thermodynamic Analysis ◽  
Second Law Of Thermodynamics ◽  
Combined Heat And Power ◽  
Second Law ◽  
Entropy Production Rate ◽  
Prime Mover ◽  
Operation Condition ◽  
Laws Of Thermodynamics

In modeling and designing micro combined heat and power cycle most important point is recognition of how the cycle operates based on the first and second laws of thermodynamics simultaneously. Analyzing data obtained from thermodynamic analysis employed to optimize MCHP cycle. The data obtained from prime mover optimization has been used for basic stimulus cycle. Assumptions considered for prime mover optimization has been improved, for example in making optimum operation condition by using genetic algorithms constant pressure combustion chamber was considered. The exact value of downstream and upstream pressure changes in the combustion chamber reaction has been obtained. After extraction of the appropriate relationship for the primary stimulus cycle, data required for the overall cycle analysis identified, By using these data optimum total cycle efficiency and constructing the first and second laws of thermodynamics has been calculated for it. After reviewing Thermodynamic governing relations in each cycle and using the optimum values that the prime mover has been optimized with, other cycles have been optimized. In best performance condition of cycle, electrical efficiency was 41 percent and the overall efficiency of the cycle was 88 percent, respectively. After using the second law of thermodynamics mathematical model Second law of thermodynamics efficiency and entropy production rate was estimated. Second law of thermodynamics yield best performance against the 45.14 percent and the rate of entropy production in this case equal to 0.099 kW/K respectively.

Thermodynamic Analysis of the First Stage of Heavy Water Production

2006 ◽  
Author(s):  
R. Hilda Cha´vez ◽  
Javier de J. Guadarrama ◽  
Abel Herna´ndez-Guerrero
Keyword(s):  
Thermodynamic Analysis ◽  
Heavy Water ◽  
Second Law Of Thermodynamics ◽  
Chemical Processes ◽  
Second Law ◽  
Water Production ◽  
Entropy Increase

The present paper describes the thermodynamic analysis of the first stage of enrichment of heavy water production by the Girdler Sulfide (GS) process. A very useful procedure for analyzing a proces is by means of the Second Law of Thermodynamics. Thermodynamic analyses based on the concept of irreversible entropy increase have frequently been suggested as pointers to sources of inefficiency in chemical processes. Furthermore, this study points out where the irreversibilities of the process are located, and provides a generalized discussion from the successful application of the technique.

scholarly journals Distinguishability of non-orthogonal density matrices does not imply violations of the second law

2019 ◽  
Author(s):  
PierGianLuca Porta Mana
Keyword(s):  
Hilbert Space ◽  
Density Matrix ◽  
Thermodynamic Analysis ◽  
Second Law Of Thermodynamics ◽  
The Other ◽  
Second Law ◽  
Density Matrices ◽  
Matrix Space ◽  
Von Neumann ◽  
Quantum Thermodynamic

The hypothetical possibility of distinguishing preparations described by non-orthogonal density matrices does not necessarily imply a violation of the second law of thermodynamics, as was instead stated by von Neumann. On the other hand, such a possibility would surely mean that the particular density-matrix space (and related Hilbert space) adopted would not be adequate to describe the hypothetical new experimental facts. These points are shown by making clear the distinction between physical preparations and the density matrices which represent them, and then comparing a "quantum" thermodynamic analysis given by Peres with a "classical" one given by Jaynes.

Thermoeconomic Indicators of Air Conditioning in a River Ship to Change the Configuration of Their Thermal Insulation

2014 ◽  
Author(s):  
J. Fajardo ◽  
B. Sarria ◽  
M. Alvarez Guerra
Keyword(s):  
System Performance ◽  
Heat Load ◽  
Air Conditioning ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Cooling Load ◽  
Air Conditioning System ◽  
Object Of Study ◽  
The Cost

This work has as object of study the energy of a river ship air conditioning system performance, using fiberglass, polyurethane or rockwool as insulation. Thermoeconomics Indicators based on second law of thermodynamics which take into account the quality of the energy and the cost of the exergy were used for research. It was observed that: (i) by increasing the thickness of the insulation the irreversibilities decreased, (ii) increases in the destroyed exergy increased generation of cooling load costs and (iii) costs per unit of exergy of heat load and area for the generation of cooling load and for investment in exergetic insulation, were minors for polyurethane.

scholarly journals Application of the Second Law of Thermodynamics in Brazilian Residential Appliances towards a Rational Use of Energy

Entropy ◽  
2020 ◽  
Vol 22 (6) ◽  
pp. 616 ◽  
Author(s):  
Carlos Eduardo Keutenedjian Mady ◽  
Clara Reis Pinto ◽  
Marina Torelli Reis Martins Pereira
Keyword(s):  
Energy Efficiency ◽  
Natural Resources ◽  
Air Conditioning ◽  
Second Law Of Thermodynamics ◽  
Exergy Efficiency ◽  
Second Law ◽  
Vapor Compression ◽  
Energy Matrix ◽  
Additional Information

This article proposes the utilization of the concepts of destroyed exergy and exergy efficiency for equipment and process performance indicators that are related to the current energy planning scenario in Brazil, more specifically with energy-efficiency labelling. Several indicators associated with these concepts are discussed, including one national program that is based on labeling the energy efficiency of several residential, commercial and industrial appliances. The grades are indicated in the equipment using values from A to G. This labeling system is useful for discriminating similar technologies used for the same function; nevertheless produced by different enterprises. For this complementary analysis, two types of refrigeration methods were compared, absorption and vapor compression; however, these energy indexes alone are not sufficient parameters to select among these two technologies, because their performance indexes definition are different. To address this, our research considers the second law of thermodynamics through exergy analysis as a proper sub-index to obtain a systematic comparison between these various indicators. It is significant to highlight that seldom research studies addressed to this problem so explicitly, in an actual governmental working solution, aiming at discussing to the society the advantage of the usage of the “quality of the energy” as a complementary index to governmental and personal choices. Results indicate that it is possible to use the destroyed exergy and exergy efficiency to help select the technology that better utilizes natural resources, considering the energy matrix of the country. Appliances for water heating and air conditioning were compared from energy and exergy viewpoint, where the last gave additional information about the quality of energy conversion process, giving a completely different trend from the energy analysis alone, without the necessity to think about the energy matrix. Later this issue is addressed from both points of view. Future studies may suggest an exergy based index. The energy efficiency suggests that electrical shower (values higher than 95%) are better than gas water heaters (83% ) in using natural resources, whereas the exergy efficiency shares similar magnitudes (about 3%). A related pattern is shown for the theoretical air conditioning systems. The vapor compression systems have an energy index higher than 3, and absorption systems lower than 1. For these circumstances, the exergy efficiency shows figures nearby 30%.

Energy and Exergy Based Analyses of a Multi-Fuelled SI Engine

2013 ◽  
Author(s):  
M. Z. Haq ◽  
A. Morshed
Keyword(s):  
Alternative Fuels ◽  
Engine Speed ◽  
Burning Velocity ◽  
Spark Ignition Engine ◽  
Si Engine ◽  
Engine Cylinder ◽  
Energy And Exergy ◽  
Si Engines ◽  
Exergy Analyses ◽  
Wiebe Function

The paper presents energy and exergy based analyses of a single cylinder, four-stroke, spark ignition engine fuelled by six different fuels namely iso-octane, methane, hydrogen, methanol, ethanol and n-butanol. Wiebe function is used to predict realistic burn rates. Since the Wiebe function parameters are generally optimized for conventional fuels, the current study modifies them for different alternative fuels using available burning velocity data. Heat losses throughout the cycle have been predicted by empirical correlations. Analyses are carried out to quantify energy and exergy of the premixed fuel-air mixture inside the engine cylinder at various phases of the cycle and some results obtained from the study are validated against data available in literature. Both energy and exergy destructions are found to be dependent on the fuels and engine operating parameters. Results show that at 1000 rpm, about 34–39% of energy contained in the fuel is converted into useful work and this quantity is found to increase with engine speed. Exergies associated with exhaust are found significantly lower than the corresponding energy values for all fuels. The present study highlights the necessity of both energy and exergy analyses to probe and identify the sources of work potential losses in SI engines in various phases of the cycle.

On Thermodynamics of Gas-Turbine Cycles: Part 1—Second Law Analysis of Combined Cycles

1985 ◽  
Vol 107 (4) ◽  
pp. 880-889 ◽  
Author(s):  
M. A. El-Masri
Keyword(s):  
Energy Balance ◽  
Second Law Of Thermodynamics ◽  
Design Tool ◽  
Second Law ◽  
Balance Analysis ◽  
Temperature Constraint ◽  
Combined Cycles ◽  
Energy Balance Analysis ◽  
Energy Balance Approach

The energy-balance approach to cycle analysis has inherent limitations. These arise from the fact that the first law of thermodynamics contains no distinction between heat and work and no provision for quantifying the “quality” of heat. Thus, while producing the correct final result, energy-balance analysis is incapable on its own of locating sources of losses. Identifying and quantifying those sources can be a useful design tool, especially in developing new, more complex systems. The second law of thermodynamics, applied in the form of entropy and availability balances for components and processes, can locate and quantify the irreversibilities which cause loss of work and efficiency. Perhaps one reason that such analysis has not gained widespread engineering use may be the additional complication of having to deal with the combustion irreversibility, which introduces an added dimension to the analysis. A method of cycle analysis, believed to circumvent this added difficulty for combustion cycles, is proposed and applied to complex combined cycles with intercooling and reheat. The fuel is treated as a source of heat, which supplies potentially available work to the cycle depending on the peak temperature constraint on work extraction. The availability is then traced as it cascades through the cycle, portions of it being wasted by the various components and processes, and the balance emerging as shaft work. Linkage with the traditional first-law efficiency is thus preserved, while establishing the location, cause, and magnitude of losses. Analysis and results for combined cycles with component irreversibilities are presented. The air-standard approximation with constant properties is used for simplicity. The turbine is treated as adiabatic since the cooling losses depend on the type of technology applied, particularly at higher temperatures. A model for quantifying those losses is presented in Part 2 of this paper.

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