In a coupled separating and throttling calorimeter, 0.9. is the drynes...
Separating and throttling calorimeter:
A separating and throttling calorimeter is a device used to determine the dryness fraction of steam. It consists of two units - a separating unit and a throttling unit. The steam sample enters the separating unit, where it is separated into wet steam and water. The wet steam then enters the throttling unit, where it undergoes a throttling process.
Dryness fraction:
The dryness fraction of steam is defined as the ratio of the mass of dry steam to the total mass of the steam sample. It represents the quality of the steam, with a dryness fraction of 1 indicating completely dry steam and a dryness fraction of 0 indicating saturated water.
Given information:
In the separating unit, the dryness fraction of the steam is 0.9 (or 90%). In the throttling unit, the dryness fraction is 0.95 (or 95%).
Calculating the dryness fraction:
To determine the approximate dryness fraction of the steam sample, we can assume that the mass of the water does not change during the throttling process. Therefore, the mass of the dry steam in the throttling unit is equal to the mass of the dry steam in the separating unit.
Let's assume the mass of the steam sample entering the separating unit is 1 kg.
- In the separating unit, the dryness fraction is 0.9, which means the mass of dry steam is 0.9 kg and the mass of water is 0.1 kg.
- In the throttling unit, the mass of water remains the same at 0.1 kg.
- Therefore, the mass of the dry steam in the throttling unit is also 0.9 kg.
The total mass of the steam sample in the throttling unit is the sum of the mass of the dry steam and the mass of water, which is 0.9 kg + 0.1 kg = 1 kg.
Therefore, the dryness fraction of the steam sample is the mass of dry steam divided by the total mass of the steam sample, which is 0.9 kg / 1 kg = 0.9.
Conclusion:
The approximate value of the dryness fraction of the steam sample is 0.9. Therefore, the correct answer is option A.
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