Endogenous and Exogenous Exergy Destruction in Thermal Systems

2006 ◽  
Author(s):  
George Tsatsaronis ◽  
Solange O. Kelly ◽  
Tatiana V. Morosuk
Keyword(s):  
Exergy Analysis ◽  
System Optimization ◽  
Energy System ◽  
General Concept ◽  
System Component ◽  
Thermal System ◽  
Exergy Destruction ◽  
Thermal Systems ◽  
System Components ◽  
Refrigeration Machine

One of the roles of exergy analysis is to provide thermal system designers and operators with information useful for the system optimization. An exergy analysis identifies the sources of thermodynamic inefficiencies by evaluating the exergy destruction within each system component. However, care must be taken when using the total exergy destruction within a component to reach conclusions regarding the optimization of the overall energy system. The reason is that the total exergy destruction occurring in a component is not due exclusively to that component but is also caused by the inefficiencies within the remaining system components. The endogenous exergy destruction within a component is defined as that part of the component's exergy destruction that is independent of any change in the exergy destruction within the remaining components. The part of the component's exergy destruction which depends upon the changes of the exergy destruction within the other components is defined as the exogenous exergy destruction. It is apparent that the sum of endogenous and exogenous exergy destruction is equal to the total exergy destruction within the component being considered. Knowledge of the exogenous and endogenous exergy destruction for the most important components can further assist the engineer in deciding whether an adjustment in that component or in the structure of the system (i.e. in the remaining components) is required to improve the overall system. The paper presents the general concept of endogenous and exogenous exergy destruction. Using a graphical approach, the endogenous and exogenous exergy destruction of a simple gas turbine process and simple refrigeration machine are investigated.

Enhancement of Simple Gas Turbine System and Cogeneration Power Plant Using Dual Fueling of Combustion Chamber: Based on Endogenous and Exogenous Exergy Destruction Concepts

2010 ◽  
Author(s):  
Nayyer Razmara ◽  
Rahim Khoshbakhti Saray
Keyword(s):  
Power Plant ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Exergy Analysis ◽  
Combustion Process ◽  
System Optimization ◽  
General Concept ◽  
System Component ◽  
Exergy Destruction ◽  
Dual Fueling

Exergy analysis provides useful information about the system optimization. An exergy analysis identifies the sources of thermodynamic inefficiencies by evaluating the exergy destruction within each system component. Splitting the exergy destruction into endogenous/exogenous parts represents a new development in the exergy analysis of energy conversion systems. The present work is an attempt to investigate the combustion process in a simple gas turbine and a cogeneration power plant based on the general concept of endogenous and exogenous exergy destruction. Therefore, using a graphical approach, the advanced exergy analysis is applied to both cycles with different fuels such as methane and diesel. Also, dual-fueling of combustion chamber is investigated based on the aforementioned approach in which 90% substitution of methane fuel for diesel one is considered. It is found that, in both cycles the combustion chamber has the largest value of the endogenous exergy destruction. The exergetic efficiency of combustion chamber increases when methane fuel is substituted for diesel fuel. Therefore, cycles efficiencies have been enhanced when fuel is substituted for diesel one. The results obtained here may provide some useful information for the optimal design and performance improvement of these cycles.

scholarly journals Advanced Exergy Analysis in the Dynamic Framework for Assessing Building Thermal Systems

Entropy ◽  
2019 ◽  
Vol 22 (1) ◽  
pp. 32 ◽  
Author(s):  
Ana Picallo-Perez ◽  
José M Sala ◽  
George Tsatsaronis ◽  
Saeed Sayadi
Keyword(s):  
Exergy Analysis ◽  
Energy System ◽  
Building Energy ◽  
Hot Water ◽  
Exergy Destruction ◽  
Dynamic Calculation ◽  
Thermal Systems ◽  
Dynamic Framework ◽  
Building Energy System ◽  
First Time

This work applies the Dynamic Advanced Exergy Analysis (DAEA) to a heating and domestic hot water (DHW) facility supplied by a Stirling engine and a condensing boiler. For the first time, an advanced exergy analysis using dynamic conditions is applied to a building energy system. DAEA provides insights on the components’ exergy destruction (ED) by distinguishing the inefficiencies that can be prevented by improving the quality (avoidable ED) and the ones constrained because of technical limitations (unavoidable ED). ED is related to the inherent inefficiencies of the considered element (endogenous ED) and those coming from the interconnections (exogenous ED). That information cannot be obtained by any other approach. A dynamic calculation within the experimental facility has been performed after a component characterization driven by a new grey-box modelling technique, through TRNSYS and MATLAB. Novel solutions and terms of ED are assessed for the rational implementation of the DAEA in building energy installations. The influence of each component and their interconnections are valuated in terms of exergy destruction for further diagnosis and optimization purposes.

Advanced Exergoeconomic Evaluation and Its Application to Compression Refrigeration Machines

2007 ◽  
Author(s):  
George Tsatsaronis ◽  
Tatiana Morosuk
Keyword(s):  
Energy Conversion ◽  
Exergy Analysis ◽  
System Component ◽  
Exergy Destruction ◽  
Conversion System ◽  
Investment Cost ◽  
Energy Conversion System ◽  
The Cost ◽  
Refrigeration Machine

Splitting the exergy destruction within each component of an energy conversion system into endogenous/exogenous and unavoidable/avoidable parts enhances an exergy analysis and improves the quality of the conclusions obtained from the analysis. The potential for improving each system component is identified and priorities, according to which the design of components should be modified, are established. We call this detailed exergy analysis advanced exergy analysis. For improving the cost effectiveness of an energy conversion system, splitting the investment cost into endogenous/exogenous and unavoidable/avoidable parts is also helpful. The designer should focus on the avoidable thermodynamic inefficiencies (exergy destruction), their costs and the avoidable investment costs. The paper discusses the calculation of these costs in general and the resulting advanced exergoeconomic evaluation that is based on the avoidable endogenous and the avoidable exogenous values for exergy destruction, cost of exergy destruction and investment cost. An application of this methodology to a compression refrigeration machine is presented.

scholarly journals MODELING OF THERMAL INSTALLATIONS BASED ON THERMODYNAMIC APPROACHES

2021 ◽  
pp. 53-58
Author(s):  
V. Voloshchuk ◽  
Eu. Nikiforovich
Keyword(s):  
Exergy Analysis ◽  
Ecological Assessment ◽  
Impact Factors ◽  
Thermal Systems ◽  
Modeling Methods ◽  
Combined Application ◽  
Conversion System ◽  
System Components ◽  
Energy Conversion System ◽  
Exergetic Analysis

The most widespread approaches to the study of thermal systems involve the iterative implementation of the following steps: thermodynamics, heat and mass transfer, hydrodynamics, economics and ecology. Such methodology cannot combine economic, environmental and thermodynamic aspects from the beginning of the analysis. It does not provide information concerning not only external, but also internal, caused by thermodynamic inefficiencies of system components, impact factors on economic and ecological characteristics. Modeling methods based on the combined application of the First and Second Laws of Thermodynamics (methods of entropy and exergetic analysis), and their combination with economic and environmental assessment make it possible to identify the location, magnitude, causes, costs and environmental impact of thermodynamic inefficiencies in an energy conversion system. The paper proposes the improvement of methods for modeling thermal systems on the base of exergy analysis. It has been shown that combining exergetic, economic and ecological assessment can significantly simplify tasks of finding parameters and structure of the studied system. Examples of implementation of such studies have been presented.

scholarly journals Exergy Efficiency Optimization for Gas Turbine Based Cogeneration Systems

2013 ◽  
Author(s):  
Ana C. Ferreira ◽  
Senhorinha F. Teixeira ◽  
José C. Teixeira ◽  
Manuel L. Nunes ◽  
Luís B. Martins
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Exergy Analysis ◽  
Exergy Efficiency ◽  
Plant Performance ◽  
System Component ◽  
Inlet Temperature ◽  
Exergy Destruction ◽  
Turbine Inlet Temperature ◽  
Turbine Inlet

Energy degradation can be calculated by the quantification of entropy and loss of work and is a common approach in power plant performance analysis. Information about the location, amount and sources of system deficiencies are determined by the exergy analysis, which quantifies the exergy destruction. Micro-gas turbines are prime movers that are ideally suited for cogeneration applications due to their flexibility in providing stable and reliable power. This paper presents an exergy analysis by means of a numerical simulation of a regenerative micro-gas turbine for cogeneration applications. The main objective is to study the best configuration of each system component, considering the minimization of the system irreversibilities. Each component of the system was evaluated considering the quantitative exergy balance. Subsequently the optimization procedure was applied to the mathematical model that describes the full system. The rate of irreversibility, efficiency and flaws are highlighted for each system component and for the whole system. The effect of turbine inlet temperature change on plant exergy destruction was also evaluated. The results disclose that considerable exergy destruction occurs in the combustion chamber. Also, it was revealed that the exergy efficiency is expressively dependent on the changes of the turbine inlet temperature and increases with the latter.

scholarly journals SPLITTING THE TOTAL EXERGY DESTRUCTION INTO THE ENDOGENOUS AND EXOGENOUS PARTS OF THE THERMAL PROCESSES IN A REAL INDUSTRIAL PLANT

2016 ◽  
Vol 14 (2) ◽  
pp. 199 ◽  
Author(s):  
Goran Vučković ◽  
Mića Vukić ◽  
Mirko Stojiljković ◽  
Miloš Simonović
Keyword(s):  
Steam Generator ◽  
Energy System ◽  
The Other ◽  
Industrial Plant ◽  
Thermal Processes ◽  
Exergy Destruction ◽  
Dominant Effect ◽  
System Components

The total exergy destruction occurring in a component is not only due to the component itself (endogenous exergy destruction) but is also caused by the inefficiencies of the remaining system components (exogenous exergy destruction). Hence care must be taken in using the total exergy destruction of a component for making decisions to optimize the overall energy system. In this paper, a complex industrial plant is analyzed by splitting the component’s exergy destruction into its endogenous part (the part resulting totally from the component’s irreversibilities) and its exogenous part (resulting from the irreversibilities of the other components within the system). It is observed that the steam generator has the dominant effect. From the total exergy destruction in the steam generator, 1,097.63 kW or 96.95% come from internal irreversibilities in the component, while the influence of other components on the loss of useful work in the steam generator is only 3.05%.

Advanced Exergetic Analysis is a Modern Tool for Evaluation and Optimization of Refrigeration Systems

2015 ◽  
pp. 85-105
Author(s):  
Tatiana Morosuk ◽  
George Tsatsaronis
Keyword(s):  
Practical Method ◽  
System Component ◽  
Exergy Destruction ◽  
Real Potential ◽  
The Real ◽  
Exergetic Analysis ◽  
Refrigeration Machine ◽  
Modern Tool

In the last decades an exergetic analysis became increasingly popular because this analysis identifies the location, magnitude and sources of thermodynamic inefficiencies. A conventional exergetic analysis, however, does not consider (a) the real potential for improving a system nor (b) the interactions among the components of the system. The interactions among different components of the same system can be estimated and the quality of the conclusions obtained from an exergetic evaluation can be improved, when the exergy destruction (irreversibilities) within each system component are split into endogenous/exogenous and avoidable/ unavoidable parts. We call this advanced exergetic analysis. The purpose of this chapter is to demonstrate that the advanced exergetic analysis is a practical method that allows engineers to extract useful information and conclusions and to develop ideas and solutions that cannot be suggested by other methods. In this chapter the conventional and advanced exergetic analysis are applied to an air refrigeration machine.

Exergogravimetric Design for Increased SOFC System Power Density

2013 ◽  
Author(s):  
Comas Haynes ◽  
Ryan Miller
Keyword(s):  
System Design ◽  
Exergy Analysis ◽  
Control Volume ◽  
Process Analysis ◽  
Preliminary Finding ◽  
Energy System ◽  
Specific Power ◽  
Thermal System ◽  
Component Level ◽  
Efficient System

Compact subsystems are pivotal to aeronautical applications, inclusive of advanced energy concepts. Regarding size minimization, an “exergogravimetric” approach has recently begun that attempts an exergy-aided weight reduction of advanced energy systems (inclusive of fuel); and this is based upon the added design insights afforded by Second Law considerations. The chief rationale and objective are to leverage the advancements that exergoeconomics affords in the realm of cost-effective thermal system design to aid size-effective thermal system design. A conceptual solid oxide fuel cell (SOFC) system for long-duration unmanned aerial vehicle (UAV) applications has been initially modeled and simulated, inclusive of exergy analysis, and preliminary findings are discussed. Additionally, the concepts and methodologies can be extended to other advanced energy system technologies. There are project-specific and general milestones and conclusions drawn from the initial investigation. Specific to the project, a conceptual SOFC system simulation was completed via physics-based and literature-verified models along with structured language (i.e., MATLAB) numerical implementation. Specific component-level contributions to lost power potential and added mass were preliminarily resolved. Thermal exergy destruction and loss are predominant sources of unutilized specific power potential. Operational and physical degrees-of-freedom were explored, with the aid of exergy analysis, to resolve better design pathways. This included a counterintuitive preliminary finding that larger cell interconnects may facilitate smaller and more efficient system operation. Generally, exergy analyses allow a system design opportunity to gain higher resolution insights (i.e., to component- and spatial-extents) regarding inefficiencies throughout a thermal system, and this is afforded by the comprising blend of 1st Law and 2nd Law considerations. There is also an added means of accounting for 2nd Law effects. The traditional 2nd Law verification point of entropy generation being non-negative does not provide the same level of process analysis closure as does the related constraint that all processes have to account for exergy being stored, converted, destroyed or rejected through any defined control volume. This alternative 2nd Law perspective facilitates verification and validation of simulations.

scholarly journals Integrated Energy System Optimization Based on Standardized Matrix Modeling Method

2018 ◽  
Vol 8 (12) ◽  
pp. 2372 ◽  
Author(s):  
Jingchao Li ◽  
Yulong Ying ◽  
Xingdan Lou ◽  
Juanjuan Fan ◽  
Yunlongyu Chen ◽  
...  
Keyword(s):  
Energy Flow ◽  
Nonlinear Problems ◽  
System Optimization ◽  
Energy System ◽  
Optimization Method ◽  
Modeling Method ◽  
Matrix Modeling ◽  
System Components ◽  
Integrated Energy System ◽  
Energy Conversion Devices

Aiming at the optimization of an integrated energy system, a standardized matrix modeling method and optimization method for an integrated energy system is proposed. Firstly, from the perspective of system engineering, the energy flow between energy conversion devices is used as a state variable to deal with nonlinear problems caused by the introduction of scheduling factors, and a standardized matrix model of the integrated energy system is constructed. Secondly, based on the proposed model, the structural optimization (i.e., energy flow structure and equipment type), design optimization (i.e., equipment capacity and quantity), and operation optimization for the integrated energy system can be achieved. The simulation case studies have shown that the proposed integrated energy system standardized matrix modeling method and optimization method are both simple and efficient, and can be effectively used to decide the system components and their interconnections, and the technical characteristics and daily operating strategy of the system components.

Exergy Analysis of a Solar Heating System

1995 ◽  
Vol 117 (3) ◽  
pp. 249-251 ◽  
Author(s):  
Geng Liu ◽  
Y. A. Cengel ◽  
R. H. Turner
Keyword(s):  
Exergy Analysis ◽  
Energy Analysis ◽  
Second Law Of Thermodynamics ◽  
Heating System ◽  
Solar Heating ◽  
Second Law ◽  
Exergy Destruction ◽  
Thermal Systems ◽  
Heating Systems ◽  
Second Law Analysis

Exergy destruction associated with the operation of a solar heating system is evaluated numerically via an exergy cascade. As expected, exergy destruction is dominated by heat transfer across temperature differences. An energy analysis is also given for comparison of exergy cascade to energy cascade. Efficiencies based on both the first law and second law of thermodynamics are calculated for a number of components and for the system. The results show that high first-law efficiency does not mean high second-law efficiency. Therefore, the second-law analysis has been proven to be a more powerful tool in identifying the site losses. The procedure used to determine total exergy destruction and second law efficiency can be used in a conceptual design and parametric study to evaluate the performance of other solar heating systems and other thermal systems.

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