ECS_Midterm

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ChrisC
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66132
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ECS_Midterm
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2011-02-13 19:07:05
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Energy Conversion Systems
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Energy Conversion Systems
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  1. Money in bank:Purchasing goods/services is the same as ___________ to Work
    Energy
  2. Which of the following is a unit of power.
    i) kJ
    ii) kW
    iii) kWh
    kW
  3. True or false: Hydrogen is no a primary energy source?
    True
  4. What characteristic is common between thermal and light energy?
    Both are electromagnetic waves
  5. Energy can neither be created nor destroyed. So what law prevents us from recycling energy?
    i) Law of conservation
    ii) First law of thermodynamics
    iii) Third law of thermodynamics
    Third law of thermodynamics
  6. What is the given definition of work? (3 prts)
    • Ability to do work.
    • Can not be created or destroyed.
    • Total amount of energy in the world is constant.
  7. Name the seven forms of energy.
    • Mechanical (Kinetic, Potential)
    • Chemical
    • Thermal
    • Electrical
    • Nuclear (Fission, Fusion)
    • Light (Electromagnetic)
    • Sound
  8. What are the components of an energy conversion system?
    • 1. Source of energy
    • 2. Conversion devices
    • 3. Transportation
    • 4. Storage
    • 5. End use
  9. What three things are necessary for the formation of fossil fuels?
    • 1. High Pressure
    • 2. High Temperature.
    • 3. Long Time (>100 Million Years)
  10. Give the stages of formation of coal.
    Dead Plants ---> Pear ---> Lignite ---> Bituminous Coal ---> Anthracite
  11. What are the following definitions:
    1) Capable of synthesizing organic molecules from inorganic precursors and storing biochemical energy ("Self Feeding").
    2) Obtain energy from feeding on organisms ("Consumer").
    3) Eat plants, usually autotrophs.
    4) Eat meat, usually herbivores.
    • 1) Autotroph
    • 2) Heterotroph
    • 3) Herbivore
    • 4) Carnivore
  12. What is the photosynthesis reaction?
    6CO2 + 6H2O + sun(400 - 700 nm) ---> C6H12O6 + 6CO2
  13. What interesting emissions phenomena does biomass have?
    It is carbon neutral.
  14. What are the food energy conversion equations (4)?
    • 1. Food Intake = Assimilation + Excretion
    • 2. Assimilation = Gross Production = Net production (Formation of new tissue) + Respiration (Maintenance)
    • 3. Assimilation Efficiency = Assimilation/Ingestion(Food Intake)
    • 4. Net Production Efficiency = NPP/GPP.
  15. What is the cellular respiration conversion equation?
    • C6H12O6 --> 6CO2 + 6H2O + energy
    • where energy is trapped by ATP (Adenosine Triphosphate)
  16. What is the definition of food calorie (Cal)
    • 1 Cal = 1000 cal = 4.2 KJ
    • Heat required to heat 1 kg (1L) of water by 1 degree.
  17. What is Global Warming Potential (GWP)?
    Measure of how much a gas contributes to global warming with respect to CO2
  18. What are three ways nature may fix global warming?
    • 1) Higher temp may increase vegetation in polar regions which would absorb more CO2.
    • 2) Kind of vegetation may change leading to more CO2 absorption.
    • 3) Rising ocean may absorb more CO2, but this is a slow process.
  19. When did Canada sign Kyoto Protocol?
    • Signed in 1998, and ratified in 2002 for 6%(against 1990).
    • Note that amount required was only 5%.
  20. What are the three things that countries can do to "lower emissions"?
    • 1) Emission trading (Carbon market)
    • 2) Clean development mechanism
    • 3) Joint implementation
  21. What are the components of the Kaya Equation of emission?
    • Emission intensity, population, GDP per capita, energy per GDP
    • CO2 = (CO2/E)(E/GDP)(GDP/POP)(POP)
  22. What does BASIC stand for?
    The fastest developing countries in the world: Brazil, South Africa, India, China
  23. What are the important conferences of parties (COP)?
    • COP 3 - Kyoto, Japan (1997)
    • COP 15 - Copenhagen, Denmark (2009)
    • COP 16 - Cancun, Mexico (2010)
  24. What does UFNCCC stand for?
    United Nations Framework Convention on Climate Change
  25. What effects the finite rate of combustion?
    • 1) Fluid mechanics (mixing)
    • 2) Heat transfer
    • 3) Chemical reaction rates
  26. What are the three types of combustible fuels?
    • 1) Gas combustion (Easy)
    • 2) Liquid combustion (Fuel must vaporize first)
    • 3) Solid combustion (Determined by carbon combustion)
  27. What are the requirements for combustion (3Ts)?
    • 1) Time
    • 2) Temperature (T > Tign)
    • 3) Turbulence (mixing)
  28. What are the components of solid fuel?
    • 1) Ash
    • 2) Moisture
    • 3) Volatiles
    • 4) Char
  29. What are the steps of solid fuel combustion?
    • 1) Drying and heating (3s)
    • 2) Volatile release (12s)
    • 3) Ignition (25s)
    • 4) Secondary fragmentation (100s)
  30. What are the two types of volatilzation?
    • 1) Volatile burns close to the surface (O2 is readily available, and VM release is moderate).
    • 2) Volatile burns away from the surface (O2 is limited, and VM release is fast).
  31. What is the char burning process and equation?
    • 1) O2 diffuses to the surface of the particle.
    • 2) The O2 reacts with C to form CO or CO2

    • q = Cg/(1/Hm +1/Rc)
    • Hm is the mass transfer coefficient
    • Rc is the Arrhenius reaction rate.
  32. What is the mechanism factor
    Phi is a term in the mass transfer coefficient which is different depending on if CO or CO2 is the main product of the combustion reaction.

    • Phi = 1 when we have primarily CO2 (Low Temp)
    • Phi = 2 when we have primarily CO (High Temp)
  33. What are the two types of ignition?
    • 1) Forced ignition (uses an external source of energy).
    • 2) Self ignition (reactants are raised to there Tign).
  34. Give three types of industrial combustors.
    • 1) Pulverized coal (Fine suspension) ~1300C
    • 2) Stoaker fired (Fixed grate) ~1100C
    • 3) Fluidized bed (Semi-fluid) ~850C
  35. What are some benefits to fluidized bed boilers?
    • 1) Highly fuel flexible (Large thermal mass).
    • 2) Low acid gas emissions (mixing allows fir low temperature combustion).
  36. What are the two types of flame groupings?
    • 1) Named by mixing
    • Premixed flame - Mixed before ignition(Blue, intense)
    • Diffusion flame - Fuel is ignited and air mixes with it as it burns (Orange, Less intense)
    • 2) Name by fluid flow
    • Laminar - Longer flame
    • Turbulent - Shorter flame
  37. What are the major characteristics and issues with flames?
    • 1) Burning velocity
    • 2) Flammability limit
    • 3) Flame quenching
    • 4) Flame stabilization
    • 5) Adiabatic flame temperature
  38. What does the flame velocity depend on?
    • Fuel type
    • Air fuel ratio (Highest close to stochiometric ratio)
    • Inert gas (N2) amount
    • Ambient pressure
    • Temperature
    • Fluid dynamics of flow
  39. What effects the flammability limit?
    • 1) Type of fuel
    • LFL = 1/sum(yi/LFLi) - yi is mol fraction
    • 2) Temperature
    • As T Up, LFL down, UFL up
  40. What are the two aspects of flame quenching
    • 1) Hot gases and flames lose heat if they come in contact with a cooler surface.
    • 2) Free radicals tend to diffuse towards the surface of solid walls.
  41. Name two ways to get flame stabilization.
    • 1) Opposed jet systems
    • 2) Flame stabilization rings
  42. What is the adiabatic flame temperature equation?
    • HrTr = HpTp
    • Tp ~ Tr + fHc/Cp

    • Hc - heat of combustion of fuel
    • Cp - specific heat of the products
    • f - mass ratio of products and reactants
  43. Why is the actual flame temperature lower than adiabatic?
    • 1) Combustion is not instantaneous and heat is lost to surroundings.
    • 2) Above 1650C CO2 and H2O dissociate absorbing heat.
  44. What are the types of air pollutants?
    • 1) GHGs (CO2, N2O CH4, CFC, HFC)
    • 2) Acid Rain (SO2, NO, NO2)
    • 3) Others (Hg, Pb, Cd)
    • 4) Particulates
  45. Briefly describe smog, VOC, smoke, haze
    • Smog - Ozone that forms through reaction of NOx and VOC with other chemicals, especially in sunlight.
    • VOC - Unburnt hydrocarbons.
    • Smoke - Solid + Liquid + Gas (Near source).
    • Haze - Far away from source.
  46. Give three ways which NOx forms
    • 1) Thermal NOx - Oxidation of atmospheric N2 at high temperatures (T > 1000C)
    • N2 + O2 -> 2NO
    • 2) Prompt NOx - Reaction with hydrocarbon radicals (T > 1000C)
    • 3) Fuel Nitrogen - N + O -> NO2 at all temperatures
  47. Give 5 (3 and 2) ways to control SO2 emissions.
    • In Situ
    • Low surfer fuel
    • Desulferize the fuel (coal cleaning)
    • Capture SO2 in combustion using sorbents
    • Post Combustion
    • Wet scrubbing
    • Ca/S = 1.5, produces high quality CaSO4 (gypsom), disposal of wet slurry is an issue.
    • Dry scrubbing
    • Contains untreated CaO, Ca/S =2.5
  48. Give 5 (3 and 2) ways to control NOx emissions.
    • In Situ
    • (1) Fluidized combustion --best
    • (2) Low NOx burners with staged air supply (40 -60%)
    • (3) Flue gas recirculator
    • Post Combustion
    • Selective catalytic reactor (SCR)
    • >90%, uses amonium and catalysts (Ti - oxides)
    • Selective non-catalytic reactor (SNCR)
    • Cheaper alternative, not as effective
  49. Give 4 ways to control particulates post combustion.
    • (1) Fabric filter (bag house) --best
    • (2) Electrostatic precipitator
    • (3) Cyclone
    • (4) Inertia separator
  50. GWP stands for ____________
    Global warming potential
  51. GWP depends/does not depend on life of the gas in the atmosphere.
    Depends
  52. GWP of nitrous oxide is larger/smaller than that of methane?
    Larger
  53. GHG emissions from a fluidized bed boiler is higher/lower than that in a pulverized bed boiler.
    Higher
  54. The flame inside a spark plug engine is premixed/diffusion type of flame.
    Premixed
  55. The main cause of global warming is:
    A) pollution from factories and automobiles.
    B) green house effect
    C) orbital eccentricities of earth and variations in the sun's orbit.
    B) green house effect
    (this multiple choice question has been scrambled)
  56. Green house effect is caused primarily by presence in the atmosphere of
    A) water vapor
    B) ozone-destroying aerosol sprays
    C) Carbon dioxide
    C) CO2
    (this multiple choice question has been scrambled)
  57. The typical combustion temperature in a fluidized bed combustor is about:
    850C
  58. In bioenergy conversion process respiration is:
    A) energy consumed for metabolic activities
    B) energy that is used up in developing new cells
    C) energy consumed to evaporate moisture from body
    A) metabolic activities
    (this multiple choice question has been scrambled)
  59. How many ftlb/s and Kw are in 1 hp?
    550 ftlb/s and 0.74 Kw
  60. Give three differences between Canada and US energy.
    • 1) We have much more nuclear
    • 2) We export the majority of our energy
    • 3) Most of our electricity is from Hydro (Church Hill Falls for example)
  61. What is Canadas oil, natural gas, and coal in respect to the world.
    • Oil 2.2%
    • NG 1%
    • Coal 1%
  62. How much of the worlds hydroelectricity and nuclear power does Canada generate?
    • Hydro 11.7%
    • Nuclear 3.4%
  63. Rank Canada's energy usage by sector (4)
    • 1) Transportation
    • 2) Industry
    • 3) Commercial & Public Services
    • 4) Residential
  64. What is the electricity price (c/KWh) in Halifax, Montreal, and Boston.
    • Halifax 13 (7.7)
    • Montreal 7 (4.5)
    • Boston 26 (18.5)
  65. What is the conversion efficiency of photosynthesis, IC engine, and home furnace.
    • Photosynthesis 0.3%
    • IC Engine 30-40%
    • Home Furnace 90-95%
  66. What is the assimilation efficiency of plants and animals.
    • Plants 15-50%
    • Animals 60-90%
  67. Give global warming potential of HFC, NO2, CH4, CO2
    • HFC 3800
    • NO2 300
    • CH4 70
    • CO2 1
  68. Rank the fuel leaders in CO2 emissions (7)
    • Coal
    • Oil
    • Natural Gas
    • Photovoltaic
    • Nuclear
    • Wind
    • Hydro
  69. What radiation spectrum does CO2 absorb?
    3 to 10 micron wavelength
  70. Give global warming potential of HFC, NO2, CH4, CO2
    • HFC 3800
    • NO2 300
    • CH4 70
    • CO2 1
  71. What are the highest and lowest CO2 emission intensity plants in Nova Scotia?
    • Highest - Point Tupper
    • Lowest - Tufts Cove
  72. Rank Canadas GHG emissions by industry (4)
    • 1) Industry
    • 2) Transportation
    • 3) Electricity
    • 4) Heating
  73. What are Canada's three objections to hard emissions limits?
    • 1) Major polluters like India and China have not signed on.
    • 2) It may compromise Canada's competitiveness resulting in loss of jobs.
    • 3) Should do a made in Canada solution instead (Acid rain, haze, particulates)
  74. Give four outcomes of COP 16 in Cancun Mexico (2010)
    • 1) Green climate fund
    • 2) Limit global warming to 2C
    • 3) REDD reducing emissions by deforestation and degradation
    • 4) Promote technology transfer
  75. What have non signatories like China (3), India, and Brazil done to reduce emissions?
    • China
    • 1) Increased efficiency by 20%
    • 2) Advanced nuclear and coal power
    • 3) Double renewables by 2020
    • India
    • 1) Large solar energy program
    • Brazil
    • 1) Deforestation laws
  76. Typical fuel contains how much volatile matter?
    10 to 40%
  77. Give some ignition temperatures (C).
    • Methane (700)
    • CO (650)
    • Hydrogen (580)
    • Antracite (500)
    • Coal (415)
    • Kerosene (300)
  78. When was the London fog which killed 4000 people?
    1952
  79. How is smoke intensity measured?
    Ringlemans smoke chart
  80. In combustion what happens to N2O and NOx when the temperature is increased?
    • T up
    • N2O Down
    • NOx Up

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