Increasing Diesel Engine Output: Methods Explained

The question asks how to increase the output power of a diesel engine without changing its size or the engine's rotational speed (revolution per minute). This means we need a way to get more work done by the engine cylinders in each cycle, keeping the engine's physical dimensions and speed constant.

Analyzing the Options

Let's look at each option and see how it affects the engine's output:

1. By feeding more fuel:

   Diesel engines burn fuel by mixing it with air. For efficient combustion, there needs to be enough oxygen in the air to react with the fuel. If you simply inject more fuel without providing more air, the excess fuel won't burn completely. This leads to unburnt fuel, increased smoke, and does not effectively increase power output. The engine becomes 'fuel rich', which is inefficient.

2. By increasing flywheel size:

   The flywheel is a heavy wheel attached to the engine's crankshaft. Its primary function is to store rotational energy during the power stroke and release it during the other strokes (intake, compression, exhaust) to smooth out the engine's operation and provide inertia. A larger flywheel helps in smoother running and handling fluctuating loads, but it does not increase the engine's ability to generate power from combustion within the cylinders.

3. By heating incoming air:

   Heating air causes it to expand and become less dense. When the incoming air is heated before entering the cylinder, a smaller mass of air (and thus less oxygen) will fill the same volume. Since power output depends on how much fuel can be burned, and fuel combustion requires oxygen, reducing the amount of oxygen entering the cylinder will actually decrease the engine's potential power output. This is the opposite of what we want.

4. By supercharging:

   Supercharging involves using a compressor to force more air into the engine's cylinders than would naturally enter through atmospheric pressure alone. By supplying a greater mass of air (and oxygen) into each cylinder during the intake stroke, the engine can burn more fuel completely in each cycle. Burning more fuel leads to a more powerful combustion event, resulting in higher power output for the same engine size and speed. This process is often called 'forced induction'.

Conclusion on Increasing Diesel Engine Output

Based on the analysis of each option, supercharging is the method that effectively increases the amount of air (oxygen) available for combustion within the fixed volume and speed constraints of the engine. This allows more fuel to be burned, thereby increasing the engine's power output.

Therefore, supercharging is the correct way to increase the output of a diesel engine without altering its physical size or revolution speed.