Operational differences between external combustion engine and internal combustion engine?

1. External combustion engine:
- In an external combustion engine, the combustion process takes place outside of the engine, typically in a separate combustion chamber or boiler.
- The heat generated from the combustion process is transferred to a working fluid, such as water or steam, which then drives the engine's pistons or turbines.
- External combustion engines are typically larger and heavier than internal combustion engines due to the additional components required for the combustion process.
- External combustion engines are often used in applications where a continuous and steady power output is required, such as in steam turbines for power generation.

2. Internal combustion engine:
- In an internal combustion engine, the combustion process takes place inside the engine's cylinders, where fuel and air are mixed and ignited to generate power.
- The heat generated from the combustion process directly drives the engine's pistons, which in turn drive the crankshaft to produce mechanical energy.
- Internal combustion engines are typically smaller and lighter than external combustion engines, making them more suitable for use in vehicles and other mobile applications.
- Internal combustion engines are able to vary their power output more easily and quickly than external combustion engines, making them more versatile for a wide range of applications.

External Combustion Engine

- Fuel combustion: Occurs outside the engine cylinders, in a separate combustion chamber.
- Heat transfer: Heat from combustion is transferred to a working fluid (e.g., steam or air), which drives the engine.
- Efficiency: Generally lower efficiency than internal combustion engines due to heat losses during transfer.
- Emissions: Cleaner than internal combustion engines because combustion occurs separately from the working fluid.

Internal Combustion Engine

- Fuel combustion: Occurs directly within the engine cylinders, creating pressure that drives the pistons.
- Heat transfer: Heat from combustion directly expands the working fluid (e.g., air-fuel mixture) within the cylinders.
- Efficiency: Generally higher efficiency than external combustion engines due to the direct transfer of heat within the cylinders.
- Emissions: Produces more emissions, including carbon monoxide, nitrogen oxides, and particulate matter, due to the direct combustion within the cylinders.

Additional Differences

- Fuel types: External combustion engines can use various fuels, including coal, oil, and gas, while internal combustion engines primarily use gasoline, diesel, or natural gas.
- Operating pressures: External combustion engines operate at lower pressures than internal combustion engines, typically around 10-20 MPa, while internal combustion engines operate at higher pressures, up to 200 MPa.
- Power density: Internal combustion engines have a higher power-to-weight ratio than external combustion engines, making them suitable for applications where space is limited.
- Applications: External combustion engines are commonly used in power plants and some industrial applications, while internal combustion engines are widely used in vehicles, including cars, trucks, and aircraft.