Gestão de Energia: 2012/2013

Introduction

&Review of Thermodynamics

Class # 1

Prof. Tânia Sousa

taniasousa@ist.utl.pt

Docentes

• Tânia Sousa– taniasousa@ist.utl.pt

• André Pina– andre.pina@ist.utl.pt

Objectivo

1. Compreender e modelar os fluxos energéticos à escala do país, em sistemas industriais, em edifícios ou equipamentos complexos.

2. Definir acções que permitam racionalizar o uso da energia, quantificando os benefícios económicos e ambientais destas acções.

Avaliação

• Exame (50%)

• Avaliação Contínua (50%)– Trabalhos feitos por grupos de 3 alunos

– Todas (ou quase todas) as semanas são feitos trabalhos/exercícios nas aulas práticas

– Os exercícios são para entregar nas aulas

– Os trabalhos começam nas aulas e são para terminar em casa

• Portáteis?

Gestão de Energia: ConteúdoSemana Teóricas Práticas

15-02-2013 Apresentação. Revisões Termodinâmica

22-02-2013 Balanço Energético Português Exercícios

01-03-2013 Energia Primária Final e e Útil. Diagramas de Sankey Trabalho I (B.E.N)

08-03-2013Modelos analíticos para a análise energética de sistemas: diagramas de blocos

Exercícios e Trabalho II (Sankey)

15-03-2013Diagramas de blocos (cont.). Regulamento da eficiência energética na indústria (SGCIE). EROI.

Exercícios e Trabalho III (Diagrama de Blocos)

22-03-2013 Modelos Input-Output Trabalho III (Diagrama de Blocos)

29-03-2013 FÉRIAS

05-04-2013Modelos Input-Output aplicados à análise energética de sistemas

Exercícios

12-04-2013Transições Energéticas. Eficiências 2ª LeiAnálise Energética e Exergética de 150 anos em Portugal

Trabalho IV (Input-Output)

19-04-2013 Energia e Economia Exercícios

26-04-2013 Modelação da Oferta e Procura de Energia Trabalho V (LEAP)

03-05-2013 Recuperação de calor e Aquecimento Trabalho V (LEAP)

10-05-2013 Sistemas AVAC Exercícios

17-05-2013 Co-geração Exercícios

24-05-2013Regulamentos de eficiência energética nos edifícios. Passive solar and energy building design

Exercícios

Course ContentsThermodynamics

• Energy and Entropy Balances for Closed & Open Systems– Definition of the system & its boundaries

– Flows at the boundaries vs. State of the system

– Heat & Work

– Entropy Production

– Steady state vs. transient state

• Thermodynamic Cycles: power cycle, heat pump & refrigerator cycle

• 1st and 2nd Law efficiencies

• Energy Efficient Heating

• Waste Heat Recovery

• Combined Heat and Power

• Bibliography– “Fundamental of Engineering Thermodynamics” Shapiro & Moran ?

– “Energy, Management, Supply and Conservation”, Clive Beggs.

Course ContentsThermodynamics

Course Contents Portuguese Energetic Balance

• Annual energy data: – Supply, Conversion & Demand

– Efficiency of Electricity Production

– Other 1st law efficiencies

• 1st assignment – Each group analyses and compares the information of the PEB for 2011 and for other specific year

• Bibliography: – “Padronização metodológica de balanços energéticos e seu impacto no uso de indicadores”, Pedreneiras, F.

Course ContentsPrimary, Final & Useful Energy

• Definitions

• World and national patterns

• Methods to compute primary energy for renewable electricity: Physical ContentMethod & Partial Substitution Method

• The impact of the different methods on policygoals

• Bibliography: – Chapter. 2 from “Energy Economics”, Bhattacharyya.

– Cap. 2 da sebenta “Gestão de Energia”, Águas, M.

– Chapters 2 & 3 from “Energy Efficieny and the Demand for Energy Services”, Harvey, D.

Course ContentsSankey Diagrams

• Definition

• Application to the Portuguese Economy

• 2nd assignment– Each group draws the Sankey diagram using e-Sankey for the PEB for a specific year

Course ContentsProcess Chain Analysis (Block Diagrams)

• Computing the specific energy consumption in complex transformation systems:– Treatment and recycling operations

• 3rd assignment – Each group chooses a case study (e.g. the Secil), finds the correct data and describes the production process and computes the specific consumption

Course ContentsSGCIE

• Policies for promoting energy efficiency in industry

• Bibliography: – Cap. 5 da sebenta “Gestão de Energia”, Águas, M.

– Decreto-lei n.º 71/2008

– Despacho nº 17449/2008

– Despacho nº 17313/2008

Course ContentsEnergy Return on Energy Investment

• Definition, Importance

• Computation of EROI for different final energy forms

• Bibliography: – Chapter. 14 & 15 from “Energy and the Wealth of Nations”,Hall, C. & Klitgaard, K..

Course ContentsEnergy Analysis Methodologies: Input-Output

• Analysis at the Macroeconomic scale

• Computation of Direct and Indirect Effects of changes in Demand

• 4th assignment – Each group computes energy demand scenarios for Portugal for 2 & 5 & 10 years based on changes in the economic structure & compares with reality

• Application of this methodology Energy Process Chain Analysis

• Bibliography: – Chapter. 5 from “Ecological Economics”, Common & Stagl.

Course ContentsThe last 150 years in Portugal

• The evolution in the last 150 years– Evolution in the aggregate and specific 1st and 2nd

law efficiencies

– Energy transitions in Portugal

• Sankey diagrams of exergy

• Bibliography:– “Natural resource accounting: final exergy-to-useful work

analysis in Portugal from 1856 to 2009 ”, Serrenho, A, et al.

– “Transitions in Energy Systems” Chap. 16 of GEA

Course ContentsEconomic & Energy Modeling

• The links between Energy & Economic Growth & Environment

• Issues in the modeling of the interactions between energy and the environment

• An integrated Energy-Economic model– CITY On

– Energy Wars

• Competition between groups playing the game

Course ContentsRCCTE & RSECE

• Policies for promoting energy efficiency in buildings

• Bibliography:– Decreto-lei n.º 78/2006 (SCE)

– Decreto-lei n.º 79/2006 (RSECE)

– Decreto-lei n.º 80/2006 (RCCTE)

Energy Balance in Closed Systems

Energy Change = Heat + Work

Energy change in the system Flows at the boundaries

( )p cd U E EdEQ W

dt dt

+ += = +ɺ ɺ

• 1st Law: Energy Conservation

• U, Ec and Ep

• Energy transfer by Heat

• Energy transfer by Work

• Sign of heat and work fluxes

• Steady state vs. Transient

work

heat

• Choosing the boundaries – Flows, Thermodynamic System, Steady vs. Transient state

Energy Balance in Closed Systems

• Exercise:

Energy Balance in Closed Systems

• Thermodynamic Cycles

Energy Balance in Closed Systems

• 1st Law efficiencies– Power Cycle

– Heat Pump

– Refrigerator

Power Cycle Refrigerator &Heat Pump Cycles

cycle

in

W

Qη =

ɺ

ɺ

out

cycle

Q

Wγ =

ɺ

ɺ

in

cycle

Q

Wβ =

ɺ

ɺ

• Exercise:

– If P is constant then

– If PV is constant then

Energy Balance in Closed Systems

. .W Fdx P Adx P dV= − = − = −∫ ∫ ∫( )f iW P V V= − −

ln f

i i

i

VW PV

V= −

• Exercise:

– Energy Units conversion: 1kWh=3600kJ=3.6MJ

– Why is t possible that

– How much does the electricity of your fridge costsin a month?

Energy Balance in Closed Systems

1β >

Energy Balance in Open Systems

Energy Change = Heat + Work + Energy in Mass Flow

Enthalpy of component j

22

, ,2 2ji

in i i i out j j j

i j

vvdEQ W m h gz m h gz

dt

= + + + + − + +

∑ ∑ɺ ɺ ɺ ɺ

Flows at the boundaries

Mass Change = ΣMass Flows

, ,in i out j

i j

dmm m

dt= −∑ ∑ɺ ɺ

i i i ih u p v= +