Fuel

Question 1

Name five requirements when regarding fuels

Answer 1

• Storage (volume requirements)
• energy density
• distribution logistics
• compatability for the engine
• Ignition behaviour
• flammability
• emission behaiviour
• long term stability

Question 2

Briefly explain how the overall energy consumption has developed over the years

Answer 2

• overall energy consumption has constantly increased over years
• the archievements in Europe are overcompensated by the massive increase in the per-capita energy consumption in the BRIC countries, outsourcing of high energy industries

Question 3

What is meant by the term crude oil? Are there any regional differences?

Answer 3

crude oil:

• made available by digging and boring, beneth earth surface
• contains a lot of impurities
• mixture of many different types of hydrocarbons-> huge regional differences-> sulfur content (sweet/sour)

Question 4

Briefly explain the refining process of crude oil. Name two chemical and physical processes respectively

Answer 4

The physical process of separating different hydrocarbons in crude oil by fractional distillation is based on the progressively higher boiling points of different chained hydrocarbons.
chem. processes (F20):
- cracking->thermal or catalyticbreaking of long HC
- Polymerisation->combining short chains to form long chains
- reforming->restructing HC to rings
- …
physical processes (F18):
- filtering
- absorption
- extraction

Question 5

What types of molecular structures can basically be distinguished?

Answer 5

• molecular chaines: Alkanes C-C, Alkenes C–C, Alkynes C—C
• molecular rings: Naphthenes, Aromatics

Question 6

Name three different types of fossil fuels. Briefly explain their properties. What are they used for?

Answer 6

• solid fuels-> high engine wear (no practical use)
• liquid fuels-> high energy density, easy to carry (mobile application, cars ,planes)
• gaseous fuels-> low volumetric energy density, low power density(LPG,H2), high storage capacity

Question 7

Explain the term heating value / calorific value

Answer 7

heating value: amount of heat which is released at the completecombustion of a unit fuel
- lower heating value Qlhv: water is contained gaseous
- higher heating value Qhhv: combustion products are cooled down->water condenses-> heat of consensation is released; Qhhv>Qlhv
Qlhv for Petrol and Diesel ca. 42000 kJ/kg

Question 8

Explain why there is no single distillation point but a distillation curve for many fuels

Answer 8

mixture of about 200 HC-compounds -> no single distillation point, but distillation curve
- destillation depends on season (mean ambient temp.)

Question 9

Draw a diagram of a typical distillation curve. Label the axes!

Answer 9

Fuels F40

Question 10

Explain how the chemical structure of any component affects the ignition behavior

Answer 10

• if the HC-molecules have a chain structure and are less branched and long
• > more fragile
• > easy ignitable
• if the HC-molecules is short chains, highly branched or aromatic
• > less ignitable

Question 11

Name three alternative fuels

Answer 11

Biofuels:
- ethanol
- bio gas
E-Fuels:
- hydrogen
- synthetic fuels