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Gestão de Energia: 2012/2013
Introduction
&Review of Thermodynamics
Class # 1
Prof. Tânia Sousa
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= +