Another curious question, In this article, we will talk about the difference between the two most commonly used fuel Petrol or Gasoline and Diesel.
Petrol and Diesel are used as fuel in IC and CI engines. It is obtained by fractional distillation of crude oil. When crude oil is heated first, LPG gas vaporizes then petrol is obtained. Petrol is a hydrocarbon which contains 4-12 carbon-carbon atoms per molecule. The common molecules found are alkanes, cycloalkanes, aromatic chains, and asphaltenes. These alkanes also are known as paraffin have the chemical formula CnH2n+2.
The alkane from pentane to octane (C5H12-C8H18) is refined to petrol while the alkane from nonane to hexadecane (C9H20-C16H34) is refined as diesel or kerosene. Diesel fuel is used in compression ignition engines while petrol (or also called gasoline) is used in spark-ignition engines.
Also Read:Pros and Cons – diesel engine vs. petrol engine
Difference between the two:
PROPERTY |
PETROL |
DIESEL |
| Chemical name | Mostly cyclic compounds like aromatics and naphthalene | Straight chain of hydrocarbons |
| Chemical formula | Ranges from C5H12-C8H18 | Ranges from C9H20-C16H34 |
| Energy content | Less compared to diesel as it is lighter. Energy content is 33.7MJ/Kg |
Up to 16% more energy content than petrol as it is denser.
Energy content is 36.7MJ/Kg |
| CO2 emission | Less proportion of carbon atoms so less CO2 emission | More proportion of carbon atoms so more CO2 emission |
| Engines | Spark-ignition engine | Compression ignition engine |
| Viscosity | Less viscous | More as compared to petrol |
| Volatility | Greater because of the additives | Less volatile |
| Boiling temperature | 350oC-2000oC | 1800oC-3600oC |
| Power | 34.6MJ/ltr
Higher RPM for petrol engines |
38.6MJ/ltr More torque in case of diesel engines |
| Calorific value | Net calorific value=44.4MJ/kg | Net calorific value=43.4MJ/kg |
| Flammability | Has high vapor pressure. Hence more flammable | Has less vapor pressure so less flammable |
| Ignition type | Self-ignition temperature is 2460oC
For combustion of this fuel, the spark plug is required |
Self-ignition temperature is 2100oC
Self-ignited because of temperature rise due to high-pressure compression. |
| Flashpoint (the minimum temperature at which fuel is available for ignition in the evaporated state) | 430oC | Ranges from 520oC-950oC |
| Fire point(temperature at which fuel tends to burn itself and stays for five seconds) | Near about 440oC | 530oC-960oC |
| Indexing | By octane number, it is the ability to resist auto-ignition. | By cetane number, combustion speed depends on this number |
| Fuel price | Price is more | Price is less |
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