## MCQs

Total Questions : 63 | Page 1 of 7 pages
Question 1. Kirk bride criterion is given by
1.    h = 0.0057 (Re)^0.4 [k³ p² g/δ²]^1/3
2.    h = 0.0067 (Re)^0.4 [k³ p² g/δ²]^1/3
3.    h = 0.0077 (Re)^0.4 [k³ p² g/δ²]^1/3
4.    h = 0.0087 (Re)^0.4 [k³ p² g/δ²]^1/3
Answer: Option C. -> h = 0.0077 (Re)^0.4 [k³ p² g/δ²]^1/3
Answer: (c).h = 0.0077 (Re)^0.4 [k³ p² g/δ²]^1/3
Question 2. The bubble diameter at the time of detachment from the surface can be worked out from the relation proposed by
1.    Stanton
2.    Fritz
3.    Fourier
4.    Nusselt
Question 3. Consider the following phenomena
(i) Boiling
(ii) Free convection in air
(iii) Forced convection in air
(iv) Conduction in air
Identify the correct sequence (heat transfer coefficient)
1.    3 – 4 – 1 – 2
2.    4 – 1 – 3 – 2
3.    4 – 3 – 2 – 1
4.    4 – 2 – 3 – 1
Answer: Option D. -> 4 – 2 – 3 – 1
Answer: (d).4 – 2 – 3 – 1
Question 4. For n-tubes in a vertical column of the tube bank pattern, identify the correct statement.
(Where, D is the diameter of a single tube in the bank)
1.    D e = n D
2.    D e = n² D
3.    D e = (1/n) D
4.    D e = D
Answer: Option A. -> D e = n D
Answer: (a).D e = n D
Question 5. The nucleate pool boiling is influenced by the following factors
(i) Pressure
(ii) Liquid properties
(iii) Material
Identify the correct statements
1.    1, 2 and 3
2.    2 only
3.    1 and 2
4.    2 and 3
Answer: Option A. -> 1, 2 and 3
Question 6. With increase in excess temperature, the heat flux in boiling
1.    Increases continuously
2.    Decreases and then increases
3.    Decreases, then increases and again decreases
4.    Increases, then decreases and again increases
Answer: Option D. -> Increases, then decreases and again increases
Answer: (d).Increases, then decreases and again increases
Question 7. In spite of large heat transfer coefficient in boiling liquids, fins are used advantageously when the entire surface is exposed to
1.    Film boiling
2.    Transition boiling
3.    Nucleate boiling
4.    All modes of boiling
Answer: Option D. -> All modes of boiling
Question 8. The bubble diameter at the time of detachment from the surface can be worked out from the relation proposed by Fritz and is given by
(Where, β is the angle of contact)
1.    C d β [2 σ/g (p t – p v)]
2.    C d β [2 σ/g (p t – p v)]^3/2
3.    C d β [2 σ/g (p t – p v)]^1/2
4.    C d β [2 σ/g (p t – p v)]^5/2
Answer: Option C. -> C d β [2 σ/g (p t – p v)]^1/2
Answer: (c).C d β [2 σ/g (p t – p v)]^1/2
Question 9. Heat flux increases with temperature excess beyond the Leiden-frost point due to
2.    Occurrence of subcooled boiling
3.    Vapor space become large
4.    Promotion of nucleate boiling