The "burning temperature" of a diesel engine, specifically referring to the Self-Ignition Temperature (SIT) of diesel fuel, is 210°C. This is the lowest temperature at which diesel will ignite on its own, without the need for a spark or an external flame.
Understanding Diesel's Self-Ignition Temperature (SIT)
The Self-Ignition Temperature (SIT) is a crucial property of any fuel, defining the point at which it will spontaneously combust under specific conditions. For diesel fuel, this temperature is relatively low, making it ideal for compression-ignition engines.
As per the reference:
- Self-Ignition Temperature (SIT): The lowest temperature at which a fuel (like diesel or petrol) will ignite itself in the absence of a spark or flame.
Here's a comparison of SIT for common engine fuels:
| Fuel Type | Self-Ignition Temperature (SIT) |
|---|---|
| Diesel | 210°C |
| Petrol | 247°C to 280°C |
This inherent property of diesel fuel is fundamental to how diesel engines operate.
How SIT Relates to Diesel Engines
Diesel engines are known as compression-ignition engines because they do not use spark plugs for ignition. Instead, they rely on the principle of compression to achieve the necessary temperature for fuel auto-ignition:
- Air Compression: Air is drawn into the engine cylinders and highly compressed by the piston. This compression rapidly increases the air's temperature to well above the diesel's SIT.
- Fuel Injection: Once the air temperature is high enough, diesel fuel is injected into the superheated compressed air.
- Auto-Ignition: The fuel, upon contact with the hot air, reaches its self-ignition temperature and spontaneously ignites, initiating the combustion process.
While the Self-Ignition Temperature of diesel is 210°C, it's important to note that the actual peak combustion temperatures inside an operating diesel engine cylinder are significantly higher, often reaching between 1,500°C and 2,500°C. However, 210°C is the critical threshold for the fuel to begin burning without an external ignition source.
