20 th international conference on efficiency, cost, optimization, simulation and environmental...

20th International Conferenceon Efficiency, Cost, Optimization, Simulation and

Environmental Impact of Energy SystemsPadova, Italy, 25-28 June 2007

ECOSECOS20072007

Guidelines to develop software for thermoeconomic analysis of

energy systems

César Torres, Antonio Valero and Erika Perez

Centro de Investigación de Recursos y Consumos Energéticos

University of Zaragoza (SPAIN)

June 26, 2007 Guidelines to develop software for thermoeconomic analysis 2

ECOSECOS20072007 Objectives

The main objective of this paper is to show the guidelines to develop a software for the thermoeconomic analysis of energy systems, making special emphasis on:

The thermoeconomic data model

The cost formation process of products and residues

The application to thermoeconomic diagnosis


ECOSECOS20072007 Thermoeconomic Model

Economic Model

plant: ProductiveStructure…

getDeviceCost(device) : floatgetResourceCost(flow): float….

Productive Structure

plant: Stringflows: Collection <flow>devices: Collection <device> …

Flow

Id: NumberfromDevice: DevicetoDevice: Devicetype: TypeOfFlow…

Device

Id: Numbername: Stringtype: TypeOfDeviceFuel: Collection<Flow>Product:Collection<Flow>…

1..m

1..n

Thermodynamic Model

getExergy(flow) : float….

plant: ProductiveStructure…


ECOSECOS20072007 Productive and Dissipative Components

An energy system has two types of components: Productive components

Dissipative components

Productive components provide: Functional Products

Resources (Fuel) to other process

Residues and waste disposals

Dissipative components are required to: Reduce or eliminate the environment impact of residues and wastes

Maintain the operation conditions of the system, from a physical and/or a legal point of view

Improve the efficiency of the system


ECOSECOS20072007 Productive Structure

Nr Device Fuel Product Type

1 Combustor E5 E2–E1 P

2 Compressor E6 E1–E0 P

3 Turbine E2–E3 E6+E7 P

4 HRSG E3–E4 E8 P

5 Stack E4 E9 D


ECOSECOS20072007 The Fuel-Product Table

The productive diagram is a graphic representation of the thermoeconomic model of the plant. The inputs of a component are its resources

The outputs of a component are its products

The Fuel Product table is the adjacency matrix of the productive graph

F0 F1 … Fj … Fn

P0 E01 … E0j … E0n

P1 E10 E11 … E1j … E1n

… … … … … … …

Pi Ei0 Ei1 … Eij … Ein

… … … … … … …

Pn En0 En1 … Enj … Enn

Represents the production of the i-th component

becomes fuel of the j-th component

Represents the external

resources

Represents the system outputs


ECOSECOS20072007 The Fuel Product Table (II)

The productive graph and its Fuel Product table can be applied to: Thermoeconomic Optimization (TFA)

Thermoeconomic Diagnosis

Identify the cost formation process of product and residues

Analyze different aggregation level of a system

The FP table can be built automatically from the information provided by the productive structure of the system. Valero and Torres proposed in 1988 an algorithm based on the Exergy Cost Theory.


ECOSECOS20072007 FP Table Builder

ProductiveStructure

BuildIncidenceMatrices

BuildIncidenceMatrices

FlowExergyValues

Compute

Compute

Compute

Compute

Compute

FP Table


TAESS Intro Pannel


TAESS Data Input


TAESS General data 1


TAESS FP Table


TAESS FP Diagram


ECOSECOS20072007 The Cost Model

The exergy costing rules can be written as:

The cost of product is equal to the cost of the resources required to obtain it, plus the cost of the residues generated:

The cost of each flow making up the product is proportional to its exergy:

[exergy cost (kW)]

[exergoeconomic cost (€/h)]

The cost of the external resources is known:


ECOSECOS20072007 Residue Cost Distribution

The cost of a residue must be allocated to one or several productive components:

To determine the values of Cri we must define

the distribution cost ratios (RCD) as:

Therefore, the cost of the residues allocated to each productive unit, is given by:

The Residue Cost Distribution ratios represent the portion of the cost of the residue dissipated in the r-th component which has been generated in the i-th productive component.

i

jr

s

r

i


ECOSECOS20072007 Costing Equations

The unit production cost could be obtained by solving the following system of lineal equations:

is a (n x n) matrix whose elements are the unit consumption values, defined as:

is a (n x n) matrix whose elements are the ratios of the residues generated per production unit:

is a (n x 1) vector whose elements are the cost of the external resources consumed in each component per production unit:


ECOSECOS20072007 Cost Decomposition

The unit exergy cost of the product could be decomposed into two parts:

represents the unit production cost due to irreversibilities of the components:

represents the unit production cost due to the residues:

1 1,5 2 2,5 3

Combustor

Compressor

Gas Turbine

HRSG

Stack Irreversibility

Residues


ECOSECOS20072007 Cost Decomposition Activity Diagram

FP Table Build

ResidueCost

DistributionRatios

Compute

Build Compute

Compute

Compute

Compute

Compute

Compute


ECOSECOS20072007 Themoeconomic Analysis Sequence Diagram

FPR model

Thermoeconomic Analysis

FP Builder Productive Structure Thermodynamic Model Economic Model

buildFP(state)getStructure()

getExergies(state)

getResourcesCost()

FP tableproductive structure

exergies

resource cost


TAESS Matrix RP


TAESS Cost Analysis Report


TAESS Cost Formation Graph


ECOSECOS20072007 Thermoeconomic Diagnosis

It is based on the comparison of two thermodynamic states

Obtains a set of common indexes for every component of the system, whose could be used in combination with other parameters to provide useful information for the plant operation.

Relates the variation of the irreversibilities and resources consumption to the variation of the efficiency of each component.

The objective of the thermoeconomic diagnosis is the location and quantification of the anomalies causing the reduction of the system efficiency.


ECOSECOS20072007 Malfunction and Dysfunction

The irreversibility increase of a component could be decomposed into two contributions: The irreversibility increase due to a variation of the efficiency of the

component itself (MALFUNCTION).

The variation of the production objective of the component due to the malfunctions of others components (DYSFUNCTION)

The sum of the malfunctions caused by a component is called MALFUNCTION COST:

DFji represents the irreversibility increase of the component j-th caused by a malfunction in the i-th component

DFk0 represents the irreversibility increase of the component k-th caused by a variation of the outputs (final products or residues)


ECOSECOS20072007 The Fuel Impact Formula

There are two approaches to allocate the fuel impact of a system

The cost of the internal malfunctions are valuated by the production cost and they include the residues variation effect.

The costs of the internal malfunctions are valuated by the production cost due only to irreversibilities. The cost of the residues variation is considered as another contribution to the fuel impact.


ECOSECOS20072007

Compute

Thermoeconomic Diagnosis Activity Diagram

FPR Modelfor Reference

State

Build

Compute

FPR Modelfor Current

State

Compute


TAESS Diagnosis


TAESS Diagnosis Report


TAESS Irreversibility Analysis Graph


TAESS Fuel Impact Analysis Graph


ECOSECOS20072007 Productive and Dissipative Structures

It has been shown there is not only a productive structure but a dissipative structure

The dissipative structure describes how the process of residues and wastes formation is. It could be as complex as the productive one.

The productive and dissipative structures are not independent but they are interrelated. A malfunction in a component cause both an increase of the irreversibilities of the components and an increase of the residues.

Therefore, to make a correct thermoeconomic diagnosis we must define both good productive and dissipative structures.


ECOSECOS20072007

This paper should be understood as a functional description for developing software for thermoeconomic analysis of energy systems.

It includes the following new contributions: A FP table builder algorithm.

A cost decomposition methodology.

Fuel Impact analysis of residues and wastes

From now on the problem of thermoeconomic diagnosis should not be to compute cost indexes but analyzing the results.

A demo program, called TAESS, is available from the authors at http://www.exergoecology.com to illustrate the ideas presented in the paper.

Conclusions

http://www.exergoecology.com/

http://www.exergoecology.com/


Exergoeconomics web page

20th International Conferenceon Efficiency, Cost, Optimization, Simulation and

Environmental Impact of Energy SystemsPadova, Italy, 25-28 June 2007

ECOSECOS20072007

Thank you very much for your attention

20 th international conference on efficiency, cost, optimization, simulation and environmental...

Documents

n pipi e i0 e i1 e ij

pnpn e n0 e n1 e nj

p 2compressore6e6 e

n p1p1 e

thermoeconomic analysis6

thermoeconomic analysis7

ecos2007 guidelines

thermoeconomic data