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Energy Engineering

Subject : engineering
Instructions:
  • Answer 50 questions in 15 minutes.
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  • Match each statement with the correct term.
  • Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. Measure of a fuels ability to resist compression ignition - with iso- octane having an octane number of 100 and n - heptane an octane number of 0. (n - octane has an octane number of -10).






2. Bituminous coals are in the _____ - subbituminous coals in most of the west (but not Utah) - and lignites primarily in Texas and North Dakota.






3. Coal rank correlates with both hydrogen:carbon and oxygen:carbon ratio - with rank decreasing with increasing values of both ratio. ex. anthracite low ratios and lignites have high ratios






4. Not produced from any single fraction of crude in the fractionation column but rather are blends and reformates designed specifically for regional markets and specifications/regulations






5. Much lower energy density than gasoline and can be corrosive or damaging to engines and seals. Because it requires less oxygen to burn - it has slightly better engine efficiency. However - its lower energy density means a car gets considerably lower






6. Brayton Cycle






7. Constant volume combustion - isentropic and adiabatic compression and expansion - 2 stroke and 4 stroke engines use (gasoline engines)






8. Coal contributes to essentially every criteria air pollutant and to CO2 and Hg. In most cases (except CO) - coal is a major contributor.






9. Hg - As - trace other metals - no dioxins and furans






10. Good alternative to petroleum based fuels?






11. Steam Turbines (Rankine Cycle) - Gas Turbines (Brayton Cycle) - Combined Cycle (not very economically feasible) - Liquid Fuels and Other products (chemicals - Fischer Tropsh - Coal to Methanol for gasoline but less history)






12. Distillate fraction (heavier than naptha) - though it requires some additional treatment for sulfur removal -






13. Combustion rate mostly limited by heat and mass transfer rather than kinetics and is therefore much slower than in a gasoline engine - hence the constant pressure assumption - No spark plug required - glow plugs only provide local warming of system f






14. Is dominantly CH4 - but the ethane content is always >1 % and important to the fuel






15. Inlet/intake - compression - expansion/combustion/power - exhaust






16. Hard=bituminous - Brown=subbituminous/lignite






17. 100 bar inside pipelines (1/600 of normal volume) - pumping stations every 40 to 100 mi - pipelines maintained and made sure safe by pigs(devices that measure stuff to make sure nothing's wrong) distribution pipelines are lower pressure and plastic






18. Less CO2 and most other pollutants than other combustion fuels






19. Coal- fired power generation costs are roughly 50% capital and the remaining fuel and operating costs. Fuel costs have remained stable and low historically - making coal an attractive investment for power






20. Many decades and up to 100 yrs left reserves increasing due to fracking and tight gas recovery almost always seen with oil and frequently without






21. Low sulfur vs. high sulfur - bituminous used to provide most power - but switching to cleaner Wyoming subbituminous






22. More reliable than reciprocating engines because: continuous operation and fewer moving parts






23. Less efficient than either Otto or Diesel cycle at same pressure ratio/compression ratio - but in practice pressure ratio is higher leading to higher efficiencies.






24. Anthracites - bituminous coals - subbituminous coals - lignites.






25. Subbituminous much bigger because produce reflective ash






26. Fracture rock with water and other stuff - replace with sand - suck out liberated NG






27. Not very common - small particulate and SO2 and some NOx are problems for this cycle with coal






28. Measures the ability of a fuel to pressure ignite and in this regard is the opposite of the octane number.






29. Cetane numbers greater than ___ generally have no advantage over a fuel of 50. Common cetane numbers are 40-45 and 45-50 for regular and premium diesel fuels.






30. Have broader range of fuels - have higher compression ratios - nearly always super/turbo charged






31. Not too good for it. Strip mined or deep/mountain top mined






32. More expensive - heavier - and more durable/reliable than gasoline engines - Diesel cycle is less efficient than gasoline cycle at the same compression ratio - but in practice is more efficient because compression ratios are about 2x higher.






33. Fischer Tropsh synthesis






34. Contains an odorant - deliberately added so leaks will be noticed






35. Compressor stator (trailing edge points axially) - turbine stator (trailing edge has significant tangential component).






36. Are turbofans - which derive >80% of their thrust from the ducted fan rather than the high- velocity exhaust. Turbopros and other turbine- based engines also common for helicopters - ships - propeller- based aircraft - etc.






37. Refineries - which include fractionation columns - reformers - hydro crackers - catalytic crakers - cokers - reforming - and hydro treating. Know the essential role of each of these operations.;






38. Methane (70-90%) - heavier hydrocarbons (up to 20% through C4) - CO2 (up to 8% - but occasionally much higher) - H2O (usually saturated) - sometimes H2S (up to 5%) - oxygen (< 0.2%) nitrogen (up to 5%) - and other trace quantities.






39. Occurs (with a few exceptions) in the intake manifold prior to the air entering the cylinder. Air entering cylinder is a mixture of air and vaporized fuel.






40. Critical pressure (218 psi) and above - 38-39% efficient - supercritical from 45-47% efficient - materials limit max temp to 600 degC - pressure ratios up to 10 -000 because condenser reaches really low pressures






41. 2 stroke and 4 stroke - Combustion rate limited by gas - phase kinetics and is very rapid.






42. Little more than half=fuel cost - rest is transportation and distribution






43. Constant pressure combustion - isentropic and adiabatic compression and expansion






44. Brayton cycle with exhaust powering a Rankine Cycle (efficiencies of up to 60%) - possibly most economical choice - can't respond to load changes as rapidly as simple cycle






45. Higher than compression ratio in diesel or gasoline engines (note that pressure ratio is not exactly the same as a compression ratio).






46. Modern only output CO2 and no significant impact on other pollutants - Most Coal Power are old and many have significant impact on air pollution






47. 150 yrs






48. Drilling - then set up production wells with nothing above surface - production decreases exponentially with time






49. Same as Brayton cycle






50. Fuel is injected in cylinder at much higher pressures than gasoline fuel injection and through injectors designed to atomize fuel to small droplets that rapidly vaporize and burn.