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Assertion (A): If the heat fluxes in pool boiling over a horizontal surfaceis increased above the critical heat flux, the temperature difference between the surface and liquid decreases sharply.
Reason (R): With increasing heat flux beyond the value corresponding to the critical heat flux, a stage is reached when the rate of formation of bubbles is so high that they start to coalesce and blanket the surface with a vapour film.
Reason (R): With increasing heat flux beyond the value corresponding to the critical heat flux, a stage is reached when the rate of formation of bubbles is so high that they start to coalesce and blanket the surface with a vapour film.
- 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 'D'. Can you explain this answer?
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Assertion (A): If the heat fluxes in pool boiling over a horizontal su...
Ans. (d) The temperature difference between the surface and liquid increases
sharply.
sharply.
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Assertion (A): If the heat fluxes in pool boiling over a horizontal su...
Assertion (A): If the heat fluxes in pool boiling over a horizontal surface is increased above the critical heat flux, the temperature difference between the surface and liquid decreases sharply.
Reason (R): With increasing heat flux beyond the value corresponding to the critical heat flux, a stage is reached when the rate of formation of bubbles is so high that they start to coalesce and blanket the surface with a vapor film.
Explanation:
The process of pool boiling occurs when a liquid is heated on a surface and bubbles are formed due to the boiling of the liquid. The heat flux is the amount of heat energy transferred per unit area per unit time. The critical heat flux is the maximum heat flux that can be transferred without causing a sharp increase in the surface temperature.
When the heat flux is increased above the critical heat flux, the temperature difference between the surface and liquid decreases sharply. This is because, at the critical heat flux, the rate of heat transfer is at its maximum and any further increase in heat flux leads to the formation of a vapor film on the surface.
When the heat flux is increased beyond the critical heat flux, the rate of formation of bubbles becomes so high that they start to coalesce, meaning they merge together. As a result, the surface of the liquid is covered with a vapor film, which acts as an insulator and reduces the heat transfer between the surface and the liquid. This leads to a decrease in the temperature difference between the surface and liquid.
Conclusion:
From the above explanation, it can be concluded that both the assertion (A) and the reason (R) are true, but the reason (R) is not the correct explanation of the assertion (A). The decrease in temperature difference between the surface and liquid is not directly caused by the coalescence of bubbles, but rather by the formation of a vapor film on the surface. Therefore, option 'D' is the correct answer.
Reason (R): With increasing heat flux beyond the value corresponding to the critical heat flux, a stage is reached when the rate of formation of bubbles is so high that they start to coalesce and blanket the surface with a vapor film.
Explanation:
The process of pool boiling occurs when a liquid is heated on a surface and bubbles are formed due to the boiling of the liquid. The heat flux is the amount of heat energy transferred per unit area per unit time. The critical heat flux is the maximum heat flux that can be transferred without causing a sharp increase in the surface temperature.
When the heat flux is increased above the critical heat flux, the temperature difference between the surface and liquid decreases sharply. This is because, at the critical heat flux, the rate of heat transfer is at its maximum and any further increase in heat flux leads to the formation of a vapor film on the surface.
When the heat flux is increased beyond the critical heat flux, the rate of formation of bubbles becomes so high that they start to coalesce, meaning they merge together. As a result, the surface of the liquid is covered with a vapor film, which acts as an insulator and reduces the heat transfer between the surface and the liquid. This leads to a decrease in the temperature difference between the surface and liquid.
Conclusion:
From the above explanation, it can be concluded that both the assertion (A) and the reason (R) are true, but the reason (R) is not the correct explanation of the assertion (A). The decrease in temperature difference between the surface and liquid is not directly caused by the coalescence of bubbles, but rather by the formation of a vapor film on the surface. Therefore, option 'D' is the correct answer.
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Assertion (A): If the heat fluxes in pool boiling over a horizontal surfaceis increased above the critical heat flux, the temperature difference between the surface and liquid decreases sharply.Reason (R): With increasing heat flux beyond the value corresponding to the critical heat flux, a stage is reached when the rate of formation of bubbles is so high that they start to coalesce and blanket the surface with a vapour film.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 'D'. Can you explain this answer?
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Assertion (A): If the heat fluxes in pool boiling over a horizontal surfaceis increased above the critical heat flux, the temperature difference between the surface and liquid decreases sharply.Reason (R): With increasing heat flux beyond the value corresponding to the critical heat flux, a stage is reached when the rate of formation of bubbles is so high that they start to coalesce and blanket the surface with a vapour film.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 'D'. Can you explain this answer? for Mechanical Engineering 2024 is part of Mechanical Engineering preparation. The Question and answers have been prepared according to the Mechanical Engineering exam syllabus. Information about Assertion (A): If the heat fluxes in pool boiling over a horizontal surfaceis increased above the critical heat flux, the temperature difference between the surface and liquid decreases sharply.Reason (R): With increasing heat flux beyond the value corresponding to the critical heat flux, a stage is reached when the rate of formation of bubbles is so high that they start to coalesce and blanket the surface with a vapour film.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 'D'. Can you explain this answer? covers all topics & solutions for Mechanical Engineering 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Assertion (A): If the heat fluxes in pool boiling over a horizontal surfaceis increased above the critical heat flux, the temperature difference between the surface and liquid decreases sharply.Reason (R): With increasing heat flux beyond the value corresponding to the critical heat flux, a stage is reached when the rate of formation of bubbles is so high that they start to coalesce and blanket the surface with a vapour film.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 'D'. Can you explain this answer?.
Assertion (A): If the heat fluxes in pool boiling over a horizontal surfaceis increased above the critical heat flux, the temperature difference between the surface and liquid decreases sharply.Reason (R): With increasing heat flux beyond the value corresponding to the critical heat flux, a stage is reached when the rate of formation of bubbles is so high that they start to coalesce and blanket the surface with a vapour film.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 'D'. Can you explain this answer? for Mechanical Engineering 2024 is part of Mechanical Engineering preparation. The Question and answers have been prepared according to the Mechanical Engineering exam syllabus. Information about Assertion (A): If the heat fluxes in pool boiling over a horizontal surfaceis increased above the critical heat flux, the temperature difference between the surface and liquid decreases sharply.Reason (R): With increasing heat flux beyond the value corresponding to the critical heat flux, a stage is reached when the rate of formation of bubbles is so high that they start to coalesce and blanket the surface with a vapour film.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 'D'. Can you explain this answer? covers all topics & solutions for Mechanical Engineering 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Assertion (A): If the heat fluxes in pool boiling over a horizontal surfaceis increased above the critical heat flux, the temperature difference between the surface and liquid decreases sharply.Reason (R): With increasing heat flux beyond the value corresponding to the critical heat flux, a stage is reached when the rate of formation of bubbles is so high that they start to coalesce and blanket the surface with a vapour film.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 'D'. Can you explain this answer?.
Solutions for Assertion (A): If the heat fluxes in pool boiling over a horizontal surfaceis increased above the critical heat flux, the temperature difference between the surface and liquid decreases sharply.Reason (R): With increasing heat flux beyond the value corresponding to the critical heat flux, a stage is reached when the rate of formation of bubbles is so high that they start to coalesce and blanket the surface with a vapour film.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 'D'. Can you explain this answer? in English & in Hindi are available as part of our courses for Mechanical Engineering.
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ample number of questions to practice Assertion (A): If the heat fluxes in pool boiling over a horizontal surfaceis increased above the critical heat flux, the temperature difference between the surface and liquid decreases sharply.Reason (R): With increasing heat flux beyond the value corresponding to the critical heat flux, a stage is reached when the rate of formation of bubbles is so high that they start to coalesce and blanket the surface with a vapour film.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 'D'. Can you explain this answer? tests, examples and also practice Mechanical Engineering tests.
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