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Assertion (A): The air standard efficiency of the diesel cycle decreases as the load is increased Reason (R): With increase of load, cut-off ratio increases.
- a)Both A and R are individually true and R is the correct explanation of A
- b)Both A and R are individually true but R is not the correct explanation of A
- c)A is true but R is false
- d)A is false but R is true
Correct answer is option 'A'. Can you explain this answer?
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Assertion (A): The air standard efficiency of the diesel cycle decreas...
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Assertion (A): The air standard efficiency of the diesel cycle decreas...
Air standard efficiency of the diesel cycle
The air standard efficiency of the diesel cycle is a measure of the efficiency of an idealized diesel engine. It represents the ratio of the net work output of the engine to the energy input from the fuel. The higher the air standard efficiency, the more efficient the engine is.
Effect of load on air standard efficiency
The load on an engine refers to the amount of work it is required to perform. As the load on a diesel engine increases, the air standard efficiency of the diesel cycle typically decreases. This can be attributed to the following reasons:
1. Increased heat loss: As the load on the engine increases, the combustion process becomes more intense, leading to higher temperatures. This results in increased heat transfer to the engine components and surroundings, causing additional heat losses. The increased heat loss reduces the net work output of the engine and lowers its efficiency.
2. Increase in compression ratio: With an increase in load, the cut-off ratio also increases. The cut-off ratio is the ratio of the cylinder volume at the end of compression to the cylinder volume at the end of expansion. As the cut-off ratio increases, the compression ratio of the engine also increases. A higher compression ratio leads to higher peak temperatures during combustion, which in turn increases heat losses and reduces efficiency.
3. Incomplete combustion: At higher loads, there may not be sufficient time for complete combustion of the fuel-air mixture due to the shorter combustion duration. This results in incomplete combustion and higher levels of unburned fuel being expelled from the engine. The presence of unburned fuel reduces the efficiency of the engine.
Explanation of Reason (R)
The reason given in statement R is correct and supports the assertion (A). As the load on the diesel engine increases, the cut-off ratio also increases. This is because a higher load requires a larger expansion ratio, which is achieved by increasing the cut-off ratio. The increase in cut-off ratio is necessary to extract more work from the expanding gases and compensate for the increased load. However, as explained earlier, the increase in cut-off ratio also leads to higher compression ratio, increased heat losses, and incomplete combustion, resulting in a decrease in the air standard efficiency of the diesel cycle.
Therefore, both assertion (A) and reason (R) are individually true, and reason (R) is the correct explanation of assertion (A).
The air standard efficiency of the diesel cycle is a measure of the efficiency of an idealized diesel engine. It represents the ratio of the net work output of the engine to the energy input from the fuel. The higher the air standard efficiency, the more efficient the engine is.
Effect of load on air standard efficiency
The load on an engine refers to the amount of work it is required to perform. As the load on a diesel engine increases, the air standard efficiency of the diesel cycle typically decreases. This can be attributed to the following reasons:
1. Increased heat loss: As the load on the engine increases, the combustion process becomes more intense, leading to higher temperatures. This results in increased heat transfer to the engine components and surroundings, causing additional heat losses. The increased heat loss reduces the net work output of the engine and lowers its efficiency.
2. Increase in compression ratio: With an increase in load, the cut-off ratio also increases. The cut-off ratio is the ratio of the cylinder volume at the end of compression to the cylinder volume at the end of expansion. As the cut-off ratio increases, the compression ratio of the engine also increases. A higher compression ratio leads to higher peak temperatures during combustion, which in turn increases heat losses and reduces efficiency.
3. Incomplete combustion: At higher loads, there may not be sufficient time for complete combustion of the fuel-air mixture due to the shorter combustion duration. This results in incomplete combustion and higher levels of unburned fuel being expelled from the engine. The presence of unburned fuel reduces the efficiency of the engine.
Explanation of Reason (R)
The reason given in statement R is correct and supports the assertion (A). As the load on the diesel engine increases, the cut-off ratio also increases. This is because a higher load requires a larger expansion ratio, which is achieved by increasing the cut-off ratio. The increase in cut-off ratio is necessary to extract more work from the expanding gases and compensate for the increased load. However, as explained earlier, the increase in cut-off ratio also leads to higher compression ratio, increased heat losses, and incomplete combustion, resulting in a decrease in the air standard efficiency of the diesel cycle.
Therefore, both assertion (A) and reason (R) are individually true, and reason (R) is the correct explanation of assertion (A).
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Assertion (A): The air standard efficiency of the diesel cycle decreases as the load is increased Reason (R): With increase of load, cut-off ratio increases.a)Both A and R are individually true and R is the correct explanation of Ab)Both A and R are individually true but R is not the correct explanation of Ac)A is true but R is falsed)A is false but R is trueCorrect answer is option 'A'. Can you explain this answer?
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ample number of questions to practice Assertion (A): The air standard efficiency of the diesel cycle decreases as the load is increased Reason (R): With increase of load, cut-off ratio increases.a)Both A and R are individually true and R is the correct explanation of Ab)Both A and R are individually true but R is not the correct explanation of Ac)A is true but R is falsed)A is false but R is trueCorrect answer is option 'A'. Can you explain this answer? tests, examples and also practice Mechanical Engineering tests.
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