24 Questions
What is the main consequence of a higher compression ratio in an engine?
More power can be provided
What is the primary cause of knocking in an engine?
Ignition of the fuel mixture before the spark plug fires
What is the first law of thermodynamics also known as?
The law of conservation of energy
What is the result of transforming thermal energy into ordered work?
Going against the second law of thermodynamics
What is the purpose of blending branched alkanes with fuel?
To improve the fuel's resistance to knocking
What is the main limitation of increasing the compression ratio in an engine?
Knocking
What is the result of the second law of thermodynamics?
Entropy of the universe is increasing
What is the relationship between the compression ratio and power output in an engine?
Higher compression ratio results in more power
What is the energy required to break the C-H bond?
410
Which fuel has the highest Lower Heating Value?
Biodiesel
What is the main difference between the Lower Heating Value and the Higher Heating Value?
The state of the product of water
Which of the following fuels has the highest energy density?
Liquified Natural Gas (LNG)
What is the bond energy of O=O?
494
Which of the following fuels is a type of alternative fuel?
Ethanol
What is the Higher Heating Value of Hydrogen?
61,013
Which of the following fuels has the lowest Lower Heating Value?
Compressed Natural Gas (CNG)
What is the primary function of a fuel?
To generate energy
How do fuels generate energy?
Through chemical reactions
What determines the energy value of a fuel?
The calorific value of the fuel
What is the relationship between the First and Second Laws of Thermodynamics and energy production from fuels?
The First Law states that energy cannot be created or destroyed, while the Second Law states that energy cannot be converted from one form to another with 100% efficiency
What is the purpose of the octane number?
To measure the tendency of a fuel to cause engine knocking
What is the classification of fuels based on their physical state?
Solid, liquid, and gas
What is the term for a reactant that limits the whole chemical reaction?
Limiting reactant
What is the significance of the 0.19 moles of oxygen used in combustion?
It is the amount of oxygen that limits the whole chemical reaction
Study Notes
Fuels and Energy Relationships
- A fuel is a substance that can be used as a source of power.
- Fuels can be classified into:
- Solid fuels
- Liquid fuels
- C–H (hydrocarbon) fuels
Calorific Values of Fuels
- Calorific values are the energy values of fuels.
- The Lower Heating Value is calculated with the product of water being in vapor form.
- The Higher Heating Value is calculated with the product of water being in liquid form.
- Examples of calorific values of different fuels:
- Biodiesel: 119,550 - 127,960
- Propane (LPG): 84,250 - 91,420
- Compressed Natural Gas (CNG): 20,160 - 22,453
- Liquified Natural Gas (LNG): 21,240 - 23,726
- Ethanol: 76,330 - 84,560
- Methanol: 57,250 - 65,200
- Hydrogen: 51,585 - 61,013
Octane Number and Engine Knocking
- Octane number is a measure of a fuel's resistance to knocking.
- Knocking is a rapid pinging or knocking sound that comes from an engine when it is pushed to produce a lot of power quickly.
- Knocking can result in a loss of power, inefficiency, and fractures in the top surface of the piston.
Thermodynamics and Energy Production
- The First Law of Thermodynamics: Energy is conserved and transformed from one form to another.
- The Second Law of Thermodynamics: The entropy of the universe is increasing.
- The relationship between the First and Second Laws of Thermodynamics and energy production from fuels.
This quiz covers the basics of fuels and energy, including definitions and types of fuels. Students will learn about the relationships between fuels and energy.
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