gestão de energia: 2013/2014 introduction & review of thermodynamics class # 1 prof. tânia...
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Gestão de Energia: 2013/2014
Introduction&
Review of ThermodynamicsClass # 1
Prof. Tânia [email protected]
Docentes
• Tânia Sousa– [email protected]
• Carla Silva– [email protected]
• Carlos Silva– [email protected]
• André Pina– [email protected]
Avaliação
• Exame (50%) com nota mínima 9.5 val.• Avaliação Contínua (50%)
– Trabalhos feitos por grupos de 2/3 alunos
– Os trabalhos começam nas aulas e são para terminar em casa
– A avaliação é feita nas aulas e com os trabalhos
• Trazer um portátil por grupo para as aulas práticas
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.
Gestão de Energia: ConteúdoSemana Teóricas Práticas
21-02-2014 Apresentação. Revisões Termodinâmica
28-02-2014 Balanço Energético Português Exercícios
07-03-2014 Energia Primária Final e e Útil. Diagramas de Sankey Transições Energéticas. Análise da Eficiência de Sistemas Energéticos
Trabalho I (B.E.N)
14-03-2014 Modelos analíticos para a análise energética de sistemas: diagramas de blocos
Trabalho II (Sankey)
21-03-2014Eficiência Energética na Indústria. Regulamento da eficiência energética na indústria (SGCIE).
Exercícios
28-03-2014Eficiência Energética nos edifícios.Regulamentos de eficiência energética nos edifícios.
Trabalho III
04-04-2014 Modelos Input-Output Exercícios
11-04-2014Energia e EconomiaMétodos de contabilização da electricidade primária.
Trabalho IV (Input-Output)
18-04-2014 FÉRIAS FÉRIAS
25-04-2014 FERIADO FERIADO
02-05-2014 Análise Ciclo de Vida Exercícios
09-05-2014 Eficiência energética nos Transportes. Regulamento da eficiência energética nos Transportes
Exercícios
14-05-2014 Auditorias Energéticas Trabalho V (Tranportes)
23-05-2014 Modelação Oferta e Procura de Energia Visita a um Laboratório Tagus Park
30-05-2014 Revisões. Exercícios
4ª feira à tarde 4ª feira manhã e à tarde
Course Contents Thermodynamics
• Energy and Entropy Balances for Closed & Open Systems
• Thermodynamic Cycles: power cycle, heat pump & refrigerator cycle
• 1st Pratical Class (exercises)
• Bibliography– “Fundamental of Engineering Thermodynamics”
Shapiro & Moran
Course Contents – T2
• The Portuguese Energetic Balance:– Supply, Conversion & Demand
– Energy CarriersBALANÇO ENERGÉTICO
tep Total de Carvão Total de PetróleoGás Natural
(*)
Gases o Outros
Derivados
Total de Eectricidade
CalorResíduos
IndustriaisRenováveisSem Hídrica
TOTAL GERAL
2008 4 = 1 a 3 22= 15 + 21 23 30 = 24 a 29 36 = 31 a 35 37 38 46 = 39 a 4547=4+22+23+30+36+37
+38+46
IMPORTAÇÕES 1. 2 327 219 16 608 384 4 163 167 923 984 24 022 754
PRODUÇÃO DOMÉSTICA 2. 1 142 338 39 800 3 190 679 4 372 817
VARIAÇÃO DE "STOCKS" 3. - 223 603 315 673 5 960 - 837 97 193
SAÍDAS 4. 24 949 3 680 661 112 918 17 634 3 836 162 CONSUMO DE ENERGIA PRIMÁRIA
5. 2 525 873 12 612 050 4 157 207 1 953 404 39 800 3 173 882 24 462 216
PARA NOVAS FORMAS DE ENERGIA
6. 2 444 703 1 079 137 2 597 143 -2 810 996 -1 472 450 1 120 1 367 391 3 206 048
CONSUMO DO SECTOR ENERGÉTICO
7. 475 376 56 103 605 301 270 736 3 1 407 519
CONSUMO COMO MATÉRIA PRIMA 1 275 842 1 275 842
DISPONÍVEL PARA CONSUMO FINAL
8. 81 170 9 781 695 1 503 961 4 159 099 1 201 714 38 680 1 806 488 18 572 807
ACERTOS 9. 9 851 - 47 340 - 1 382 12 279 - 38 580
CONSUMO FINAL 10. 71 319 9 829 035 1 505 343 4 159 087 1 201 714 38 680 1 806 209 18 611 387
AGRICULTURA E PESCAS 10.1 358 801 3 359 87 218 2 366 21 451 765
INDÚSTRIAS EXTRACTIVAS 10.2 66 103 8 444 49 882 30 844 4 155 277 INDÚSTRIAS TRANSFORMADORAS
10.3 71 319 1 085 788 1 027 157 1 340 009 1 154 293 38 680 615 382 5 332 628
CONSTRUÇÃO E OBRAS PÚBLICAS
10.4 576 210 5 063 50 490 21 631 784
TRANSPORTES 10.5 6 680 176 6 659 46 677 3 452 6 736 964
SECTOR DOMÉSTICO 10.6 552 680 300 190 1 157 672 1 180 750 3 191 292
SERVIÇOS 10.7 509 277 154 471 1 427 139 14 211 6 579 2 111 677
Course Contents – T2
• 2nd Pratical Class & 1st assignment – Each group analyses the PEB for a specific year and
compares it with 2012 (bring the computer)
• Learning Outcomes:– Be able to retrieve information from the Energetic
Balance of a country/region
– Compute electricity production efficiencies and other 1st law efficiencies for the country level
• Bibliography: – Chap. 2 “Balanço Energético Nacional -
Metodologia de Elaboração, Evolução da Estrutura e do Consumo Energético Primário”, Ramos, A.
– Chap. 2 “Energy Economics”, Bhattacharyya.
• From Primary Energy to Energy Services at different scales
Course Contents - T3
IAASA - Global Energy Assessment 2012
Course Contents - T3
Grubler, A. “Energy Transitions”
Energy Transition Energy Transition biomass to coal coal to oil
• World and national patterns of energy use• Energy Transitions
Course Contents - T3
• Sankey diagrams for different scales
• 1st and 2nd Law Efficiencies
Course Contents – T3• 2nd Pratical Class & 1st assignment
– Each group draws the Sankey diagram using e-Sankey for the PEB for a specific year for Portugal
• Learning outcomes:– Understand concepts of primary, final & useful energy
– Historical perspective on world energy use & transitions
– Use Sankey diagrams to analyse energy systems
– Understand 1st and 2nd law efficiencies
• Bibliography: – Cap. 2 da sebenta “Gestão de Energia”, Águas, M.
– Chapter 1 & 16 GEA, IAASA
– Cullen and Alwood “The efficient use of energy: Tracing the global flow of energy”, Energy Policy 2010.
• Block Diagrams Energy Analysis
• 3th Practical Class– Exercises
• Learning Outcomes– Compute the energy intensity of a product or service,
i.e., the total energy required to produce it
– Compute the impact of efficiency measures on the specific energy consumption
• Bibliography: – Cap. 5 da sebenta “Gestão de Energia”, Águas, M.
Course Contents – T4
• Energy use in industry
• SGCIE: Energy efficiency in industry
• 4th Practical Class & 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 Contents – T5
• Learning Outcomes– Apply & understand the SGCIE legislation
• Bibliography: – DL n.º 71/2008; Despachos nº 17449/2008 &
17313/2008
– Chap. 6 “Energy Efficiency and the Demand for Energy Services” Danny Harvey
Course Contents – T5
Course Contents – T6
• Energy use in Buildings– Factors controlling energy use in buildings
– Techniques to reduce energy use:
Course Contents – T6
• RCCTE & RSECE: Energy efficiency in buildings• 5th Practical Class
– Exercises
• Learning Outcomes– Learn about strategies to reduce energy use in buildings
and their impact
– Apply & understand the RCCTE & RSECE
• Bibliography:– Chap. 4 “Energy Efficiency and the Demand for Energy
Services” Danny Harvey
– Decreto-lei n.º 118/2013
Course Contents - T7
• IO Analysis at the Macroeconomic scale• Computation of Direct and Indirect Effects of
changes in Demand• 6th Pratical Class & 4th assignment
– Each group computes energy demand scenarios for a country for 2 & 5 & 10 years based on changes in the economic structure & compares with reality
• Application of this methodology to Block Diagrams Analysis
• Bibliography: – Chap. 5 “Ecological Economics”, Common & Stagl.
Course Contents – T8
• Methods to compute primary energy for renewable electricity
• EROI
Course Contents – T8
• Learning Outcomes– Critically evaluate statistics and political goals on
the weight of renewables on primary energy mixes at the country level.
– Understand & apply the concept of EROI
• BibliographyChapter. 14 & 15 from “Energy and the Wealth of Nations”,Hall, C. & Klitgaard, K..
• 7th Practical Class– Exercises
Course Contents – T8
• Energy & Economic Growth & Environment
Course Contents – T8
• Learning Outcomes– Identify the interactions between energy use,
economic growth and environmental quality
• Bibliography:– Chap. 2 & 6 “Energy at the Crossroads” Smil, V.
Course Contents – T9
• Life Cycle Assessment
• 8th Practical Class– Exercises
• Bibliography:
CO2
Bioethanol
DDG
Bioethanol Life Cycle
• Energy use in Transports
Course Contents – T10
Course Contents – T10
• Legislation• 9th Practical Class
– Exercises
• Learning Outcomes– Learn about factors that influence energy use in
transports and strategies & technologies that reduce the energy use in and their environmental impact
– Apply & understand the legislation on transports
• Bibliography:– Chap. 5 “Energy Efficiency and the Demand for
Energy Services” Danny Harvey
Course Contents – T11
• Energy Audits– Measurements
– Mass and Energy Balances
– Equipments
• 10th Practical Class– Visita de Estudo (no Tagus Park)
Course Contents – T12
• Tools to Model the Supply and Demand of Energy
• 11th Practical Class– Exercises
• Learning Outcomes– Learn about the energy modeling softwares & their
usefulness
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
• 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 – flows at the boundaries?
Energy Balance in Closed Systems
• 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
Q
out
cycle
Q
W
in
cycle
Q
W
• Exercise (Homework)
– 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 fi i
i
VW PV
V
• Exercise (Homework)
• Exercise:
– Why is it possible that ?
– How much does the electricity of your fridge costs in a month?
Energy Balance in Closed Systems
1
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 ji j
vvdEQ W m h gz m h gz
dt
Flows at the boundaries
Mass Change = Mass Flows
, ,in i out ji j
dmm m
dt
i i i ih u p v
• Exercises– 1º Write the energy balance eq.
– 2º Identify energy flows
– 3º Simplify the eq.
– For incompressible liquids at constant pressure:
Energy Balance in Open Systems
water at 50ºC 4.182 kJ/kg.K
h c T
c
• Turbines: – Produce work as a result of gas or liquid passing
through a set of blades attached to a shaft free to rotate
Energy Balance in Open Systems
22
, ,2 2ji
in i i i out j j ji j
vvdEQ W m h gz m h gz
dt
Hydraulic Turbine Wind Turbine
Wmec from Ekin of the wind
Electricity from Epot of the water Electricity from Ekin of the wind
Wind Mill
• Turbines: – Produce work as a result of gas or liquid passing
through a set of blades attached to a shaft free to rotate
Energy Balance in Open Systems
22
, ,2 2ji
in i i i out j j ji j
vvdEQ W m h gz m h gz
dt
Hydraulic Turbine Wind Turbine
Wmec from Ekin of the wind
Electricity from Epot of the water Electricity from Ekin of the wind
Wind Mill
• Exercises– Write the energy
balance eq.
– Identify energy flows
– Simplify the eq.
• What is the energy conversion taking place?
Energy Balance in Open Systems
Castelo de Bode dam
•3 turbines
• medium water fall 80 m
•Installed power: 159 MW
•Medium annual electricity production: 390 GWh
• Exercises– Write the energy
balance eq.
– Identify energy flows
– Simplify the eq.
• Potential energy is converted into electricity and kinetical energy
Energy Balance in Open Systems
Castelo de Bode dam
•3 turbines
• medium water fall 80 m
•Installed power: 159 MW
•Medium annual electricity production: 390 GWh
• Compressors (gas) & Pumps (liquids): – Used in aircraft engines, water pumping, natural gas
transport, etc
– Increase the pressure of a gas (compressor) or move fluids or slurries (pumps) using work
Energy Balance in Open Systems
22
, ,2 2ji
in i i i out j j ji j
vvdEQ W m h gz m h gz
dt
Reciprocating Compressor
Treadle Pump
Pump water using work
Pumps
Pump water using human work
Increase in pressure of gas obtainned from decreasing volume (obtainned with work)
• Compressors (gas) & Pumps (liquids): – Used in aircraft engines, water pumping, natural gas
transport, etc
– Increase the pressure of a gas (compressor) or move fluids or slurries (pumps) using work
Energy Balance in Open Systems
22
, ,2 2ji
in i i i out j j ji j
vvdEQ W m h gz m h gz
dt
Reciprocating Compressor
Treadle Pump
Pump water using work
Pumps
Pump water using human work
Increase in pressure of gas obtainned from decreasing volume (obtainned with work)
• Exercises– 1º Write the energy balance eq.
– 2º Identify energy flows
– 3º Simplify the eq.
– Ideal gas model:
– The need to cool after compression
Energy Balance in Open Systems
4
( )
CH 2.226 kJ/kg.K
PV NRT
u u T
h c T
c
Underground storing of natural gas in Carriço
Storing Pressure: 180 bar
Storing capacity: 2 155 GWh
• Heat Exchangers: – Used in power plants, air conditioners, fridges,
liquefication of natural gas, etc
– Transfer energy between fluids at different temperatures
Energy Balance in Open Systems
22
, ,2 2ji
in i i i out j j ji j
vvdEQ W m h gz m h gz
dt
Direct Contact Heat Exchanger
Counter-flow Heat exchanger
Direct Flow Heat Exchanger
• Heat Exchangers: – Used in power plants, air conditioners, fridges,
liquefication of natural gas, etc
– Transfer energy between fluids at different temperatures
Energy Balance in Open Systems
22
, ,2 2ji
in i i i out j j ji j
vvdEQ W m h gz m h gz
dt
Direct Contact Heat Exchanger
Counter-flow Heat exchanger
Direct Flow Heat Exchanger
• Exercises (homework)– 1º Write the energy balance eq.
– 2º Identify energy flows
– 3º Simplify the eq.
• Discuss boundaries
Energy Balance in Open Systems
Liquefaction of natural gas
T=-162ºC
Decrease in volume: 1/600
• Coal power plant:
Power cycle revisited
Power Cycle Refrigerator
The state variable: Entropy
• Entropy is the state variable that gives unidirectionality to time in physical processes ocurring in isolated & adiabatic systems.– Hot coffee in a cold room gets colder and not
hotter
– Radiating energy is received by the Earth from the sun and by outer space from the earth and not the other way around.
– If the valve of the tyre is opened, air gets out and not in
Entropy Balance in Closed Systems
Entropy Change = Entropy transfer in the form of heat + entropy production
Entropy change in the system
Flows at the boundariesdS Q
dt T
• Meaning of
• 2st Law:
• >0
• In adiabatic systems…
• Entropy transfer by Heat & sign
• Steady state vs. Transient
work
heat
It is not a flow at the boundary
Not relevant for entropy balance
• 2nd Law: In an adiabatic system the entropy must not decrease
• Suppose the system is adiabatic and that T2>T1
• 2nd Law: the arrow of time
Entropy Balance in Closed Systems
1 2
1 2
0
0
dS
dt
dS dSdS Q Q
dt dt dt T T
T2 T1
1 2
1 2
0
0 0
dS
dt
dS dSdS Q Q
dt dt dt T T
T2 T1