Name five requirements when regarding fuels
- Storage (volume requirements)
- energy density
- distribution logistics
- compatability for the engine
- Ignition behaviour
- flammability
- emission behaiviour
- long term stability
Briefly explain how the overall energy consumption has developed over the years
- 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
What is meant by the term crude oil? Are there any regional differences?
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)
Briefly explain the refining process of crude oil. Name two chemical and physical processes respectively
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
What types of molecular structures can basically be distinguished?
- molecular chaines: Alkanes C-C, Alkenes C–C, Alkynes C—C
- molecular rings: Naphthenes, Aromatics
Name three different types of fossil fuels. Briefly explain their properties. What are they used for?
- 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
Explain the term heating value / calorific value
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
Explain why there is no single distillation point but a distillation curve for many fuels
mixture of about 200 HC-compounds -> no single distillation point, but distillation curve
- destillation depends on season (mean ambient temp.)
Draw a diagram of a typical distillation curve. Label the axes!
Fuels F40
Explain how the chemical structure of any component affects the ignition behavior
- 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
Name three alternative fuels
Biofuels: - ethanol - bio gas E-Fuels: - hydrogen - synthetic fuels
