Which of the following is/are not (an) option(s) to let a combustion engine deliver more net work? (Multiple correct an 1.Expand the air-fuel mixture slower 2. Add more fuel before combustion 3. Compress the air more 4. Expand the air less
1. Expanding the air-fuel mixture slower is not an option to let a combustion engine deliver more net work. Slowing down the expansion of the mixture would reduce the overall efficiency of the engine.
2. Adding more fuel before combustion is an option to let a combustion engine deliver more net work. Increasing the amount of fuel will lead to a more powerful combustion, resulting in increased net work output.
3. Compressing the air more is an option to let a combustion engine deliver more net work. Increasing the compression ratio allows for a higher pressure during combustion, resulting in increased net work output.
4. Expanding the air less is not an option to let a combustion engine deliver more net work. Limiting the expansion of the air would reduce the work done by the engine and decrease overall efficiency.
To let a combustion engine deliver more net work, options 1 and 4 are not applicable.
1. Expanding the air-fuel mixture slower: This option does not let the combustion engine deliver more net work. Slowing down the expansion process can actually decrease the efficiency of the engine, reducing the net work output.
4. Expanding the air less: This option also does not contribute to increasing the net work output. Expanding the air less would mean higher pressure at the end of the expansion stroke, but it does not necessarily result in more net work. It may negatively impact the engine's efficiency.
On the other hand, options 2 and 3 can potentially help increase the net work delivered by a combustion engine:
2. Adding more fuel before combustion: By injecting additional fuel, more energy is available during the combustion process, resulting in higher pressure and work output. However, this needs to be balanced with the air-fuel ratio to avoid excessive fuel consumption and emissions.
3. Compressing the air more: Increasing the compression ratio (compressing the air more) helps to raise the temperature and pressure of the air-fuel mixture before combustion. This can lead to a more efficient combustion process and higher net work output.
To determine which option(s) are not ways to let a combustion engine deliver more net work, let's analyze each possibility:
1. Expand the air-fuel mixture slower: This option helps increase the combustion duration, allowing more energy to be extracted from the fuel. Therefore, this is a valid way to enhance the net work delivered.
2. Add more fuel before combustion: Increasing the amount of fuel before combustion results in a richer mixture, which can lead to more powerful combustion and higher net work. Hence, this is also a valid approach.
3. Compress the air more: When air is compressed more before combustion, it allows for a higher pressure and temperature during combustion. This leads to a more forceful expansion, thereby delivering more net work. Therefore, compressing the air more is a valid way to increase net work.
4. Expand the air less: This option contradicts the objective of generating more net work. By expanding the air less during the combustion process, the force exerted on the engine's piston is reduced, resulting in decreased net work delivered by the engine. Thus, expanding the air less is not a viable way to increase net work.
In conclusion, option 4, "Expand the air less," is the one that is not an option to let a combustion engine deliver more net work.