Thermodynamics and combustion modeling

Modeling fluid phase phenomena blends the conservation equations of continuum mechanics with the property equations of thermodynamics. The thermodynamic contribution becomes especially important when the phenomena involve chemical reactions as they do in combustion systems. The successful study of combustion processes requires (1) the availability of accurate thermodynamic properties for both the reactants and the products of reaction and (2) the computational capabilities to use the properties. A discussion is given of some aspects of the problem of estimating accurate thermodynamic properties both for reactants and products of reaction. Also, some examples of the use of thermodynamic properties for modeling chemically reacting systems are presented. These examples include one-dimensional flow systems and the internal combustion engine

Local heat flux measurement technique for internal combustion engines

The heat transfer from the combustion gases to the cylinder wall affects the efficiency, emissions and power output of an internal combustion engine. Measuring the heat transfer requires a heat flux sensor inside the combustion chamber that has a short response time and is able to withstand the harsh conditions during combustion. In this work, a suitable sensor is introduced and the measured wall temperature, heat flux and convection coefficient are compared to those measured with a commercial sensor. It was found that both sensors measure the same convection coefficient, but a different wall temperature and heat flux. This is because the presence of the sensor in the combustion chamber wall affects these quantities. A method is proposed to cancel this effect and calculate the actual heat flux through the cylinder wall

Analisis Exergy pada Combustion Chamber Pembangkit Listrik Tenaga Gas Uap (PLTGU) Teluk Lembu 30 MW

Combustion chamber is one of the main components in the Combined Cycle Power plant (CCPP) that serves as a supplier of heat energy. Then by the system, the thermal energy will be converted into other forms. Combustion chamber is a major cause of irreversibility in the system. Usually, the performance of a component is evaluated by using the first law of thermodynamics (conservation of energy). However, the first law of thermodynamics only assess the quantity of energy consumption. Therefore, exergy analysis is used (based on the second law of thermodynamics is about the entropy changes) which can be studied more deeply about the quality of an energy (energy available; exergy). The aim of this study is to analysze exergy destruction of combustion chamber on Combined Cycle Power Plant (CCPP) 30 MW Teluk Lembu. Exergy analysis on combustion chamber resulting the exergy destruction is 36.46 MW and exergy efficiency is 63.29%

Analysis of Internal Combustion Engine Thermodynamic Using the Second Law of Thermodynamics

The paper presents the research work done by various authors who have done research in the application of the second law of thermodynamics in analysis of the internal combustion engine and in analysis of the thermodynamics of the combustion process in an engine cylinder in spark- and compression-ignition engines. For several decades now, various authors have been trying to optimize processes in the internal combustion engine, where energy degradations occurs during combustion. It is essential to get a better insight and understanding of the sources for this energy degradation to avoid or diminish them, striving to achieve higher efficiencies of internal combustion engines as the most effective heat engine. One of the most suitable ways in research of energy degradation is application of the second law of thermodynamics in analysis of the process in internal combustion engines. Through the application of the second law of thermodynamics in analysis of the combustion process, the connection between all thermodynamic data with enthropy was achieved. By applying the numerical simulations in modeling the ICE engine processes together with the analysis by the second law of thermodynamics, we get a very potent tool for better insight and optimization of spark- and compression-ignition engines achieving lower fuel consumption and lower emissions

Stagnation Hugoniot Analysis for Steady Combustion Waves in Propulsion Systems

The combustion mode in a steady-flow propulsion system has a strong influence on the overall efficiency of the system. To evaluate the relative merits of different modes, we propose that it is most appropriate to keep the upstream stagnation state fixed and the wave stationary within the combustor. Because of the variable wave speed and upstream stagnation state, the conventional Hugoniot analysis of combustion waves is inappropriate for this purpose. To remedy this situation, we propose a new formulation of the analysis of stationary combustion waves for a fixed initial stagnation state, which we call the stagnation Hugoniot. For a given stagnation enthalpy, we find that stationary detonation waves generate a higher entropy rise than deflagration waves. The combustion process generating the lowest entropy increment is found to be constant-pressure combustion. These results clearly demonstrate that the minimum entropy property of detonations derived from the conventional Hugoniot analysis does not imply superior performance in all propulsion systems. This finding reconciles previous analysis of flowpath performance analysis of detonation-based ramjets with the thermodynamic cycle analysis of detonation-based propulsion systems. We conclude that the thermodynamic analysis of propulsion systems based on stationary detonation waves must be formulated differently than for propagating waves, and the two situations lead to very different results

UConnRCMPy: Python-based data analysis for rapid compression machines

The ignition delay of a fuel/air mixture is an important quantity in designing combustion devices, and these data are also used to validate chemical kinetic models for combustion. One of the typical experimental devices used to measure the ignition delay is called a Rapid Compression Machine (RCM). This paper presents UConnRCMPy, an open-source Python package to process experimental data from the RCM at the University of Connecticut. Given an experimental measurement, UConnRCMPy computes the thermodynamic conditions in the reaction chamber of the RCM during an experiment along with the ignition delay. UConnRCMPy implements an extensible framework, so that alternative experimental data formats can be incorporated easily. In this way, UConnRCMPy improves the consistency of RCM data processing and enables the community to reproduce data analysis procedures.Comment: 8 pages, 3 figures, presented at the 10th US National Combustion Meetin