Condensation And Boiling(Heat Transfer ) Questions and Answers
Question 1. Kirk bride criterion is given by
h = 0.0057 (Re)^0.4 [k³ p² g/δ²]^1/3
h = 0.0067 (Re)^0.4 [k³ p² g/δ²]^1/3
h = 0.0077 (Re)^0.4 [k³ p² g/δ²]^1/3
h = 0.0087 (Re)^0.4 [k³ p² g/δ²]^1/3
Explanation:-
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
Stanton
Fritz
Fourier
Nusselt
Explanation:-
Answer: Option B. -> Fritz Answer: (b).Fritz
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)
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)
D e = n D
D e = n² D
D e = (1/n) D
D e = D
Explanation:-
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, 2 and 3
2 only
1 and 2
2 and 3
Explanation:-
Answer: Option A. -> 1, 2 and 3 Answer: (a).1, 2 and 3
Question 6. With increase in excess temperature, the heat flux in boiling
Increases continuously
Decreases and then increases
Decreases, then increases and again decreases
Increases, then decreases and again increases
Explanation:-
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
Film boiling
Transition boiling
Nucleate boiling
All modes of boiling
Explanation:-
Answer: Option D. -> All modes of boiling Answer: (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)
C d β [2 σ/g (p t – p v)]
C d β [2 σ/g (p t – p v)]^3/2
C d β [2 σ/g (p t – p v)]^1/2
C d β [2 σ/g (p t – p v)]^5/2
Explanation:-
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
