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Condensation And Boiling Online Exam Quiz

Important questions about Condensation And Boiling. Condensation And Boiling MCQ questions with answers. Condensation And Boiling exam questions and answers for students and interviews.

Boiling refers to a change from the


A : a. Solid to a liquid phase

B : b. Vapor to a liquid phase

C : c. Liquid to a solid phase

D : d. Liquid to a vapor phase

The boiling process has wide-spread applications in (i) Production of steam in nuclear and steam power plants for generation and for industrial processes and space heating (ii) Absorption of heat in refrigeration and air-conditioning systems (iii) Concentration, dehydration and drying of foods and materials Identify the correct statements


A : a. 1 and 2

B : b. 2 and 3

C : c. 1, 2 and 3

D : d. 1 and 3

Maximum heat transfer rate in a modern boiler is about


A : a. 2 * 10? W/m²

B : b. 3 * 10? W/m²

C : c. 4 * 10? W/m²

D : d. 5 * 10? W/m²

Which type of boiling occurs in steam boilers employing natural convection?


A : a. Forced convection

B : b. Pool

C : c. Local

D : d. Saturated

In which type of boiling the fluid motion is induced by external means?


A : a. Pool

B : b. Local

C : c. Forced convection

D : d. Subcooled

The temperature of the liquid is below the saturation temperature and boiling takes place only in vicinity of the heated surface. This type of boiling is known as


A : a. Subcooled

B : b. Forces

C : c. Saturated

D : d. Pool

In which type of boiling the temperature of the liquid exceeds the saturation temperature?


A : a. Forced

B : b. Saturated

C : c. Pool

D : d. Saturated

The phenomenon of stable film boiling is referred to as


A : a. Nucleate effect

B : b. Boiling regimes

C : c. Leiden frost effect

D : d. Von karma effect

For water evaporating at atmospheric pressure, the burnout occurs at temperature excess slightly above


A : a. 25 K

B : b. 55 K

C : c. 75 K

D : d. 105 K

The boiling phenomenon is known to occur in how many forms?


A : a. 1

B : b. 2

C : c. 3

D : d. 4

When evaporation takes place at the liquid-vapor interface, the heat transfer is solely due to free convection and the film coefficient follows the relation


A : a. Nu = f 1 (G r) f 2 (P r)

B : b. Nu = 2 f 1 (G r) f 2 (P r)

C : c. Nu = 3 f 1 (G r) f 2 (P r)

D : d. Nu = 4 f 1 (G r) f 2 (P r)

Fritz criterion is given by


A : a. h = 1.973 (Q/A)^0.45

B : b. h = 1.973 (Q/A)^0.55

C : c. h = 1.973 (Q/A)^0.65

D : d. h = 1.973 (Q/A)^0.75

A 0.10 cm diameter and 15 cm long wire has been laid horizontally and submerged in water at atmospheric pressure. The wire has a steady state voltage drop of 14.5 V and a current of 42.5 A. Determine the heat flux of the wire. The following equation applies for water boiling on a horizontal submerged surface H = 1.54 (Q/A)^0.75 = 5.58 (d t)³ W/m² K where Q/A is the heat flux rate in W/m² and d t is the temperature difference between surface and saturation.


A : a. 1.308 * 10? W/m²

B : b. 1.308 * 10? W/m²

C : c. 1.308 * 10? W/m²

D : d. 1.308 * 10? W/m²

Natural convection heat transfer coefficients over surface of a vertical pipe and a vertical flat plate for same height. What is/are the possible reasons for this? (i) Same height (ii) Both vertical (iii) Same fluid (iv) Same fluid flow pattern Select the correct answer


A : a. 4

B : b. 1 and 2

C : c. 1

D : d. 3 and 4

The heat flux in nucleate boiling varies in accordance with


A : a. h f g

B : b. (h f g)?

C : c. 1/(h f g)²

D : d. (h f g)³

In nucleate pool boiling, the heat flux depends on


A : a. Liquid properties, material and condition of the surface

B : b. Material of the surface only

C : c. Material and roughness of the surface

D : d. Liquid properties and material of the surface

Identify the wrong statement with respect to boiling heat transfer?


A : a. The steam boilers employing natural convection have steam raised through pool boiling

B : b. Boiling occurs when a heated surface is exposed to a liquid and maintained at a temperature lower than the saturation temperature of the liquid

C : c. Leiden-frost effect refers to the phenomenon of stable film boiling

D : d. The nucleation boiling is characterized by the formation of bubbles at the nucleation sites and the resulting liquid agitation

Estimate the peak heat flux for water boiling at normal atmospheric pressure. The relevant thermo-physical properties are p f (liquid) = 958.45 kg/m³ p g (vapor) = 0.61 kg/m³ h f g = 2.25 * 10? J/kg ? = 0.0585 N/m


A : a. 1.53 * 10? W/m²

B : b. 1.53 * 10? W/m²

C : c. 1.53 * 10? W/m²

D : d. 1.53 * 10? W/m²

A 1.0 mm diameter and 300 mm long nickel wire is submerged horizontal in water at atmospheric pressure. At burnout, the wire has a current of 195 A. Calculate the voltage at burnout. The relevant thermos-physical properties are p f (fluid) = 959.52 kg/m³ p g (vapor) = 0.597 kg/m³ h f g = 2257000 J/kg ? = 0.0533 N/m


A : a. 6.15 V

B : b. 7.15 V

C : c. 8.15 V

D : d. 9.15 V

Condensation refers to a change from the


A : a. Solid to a liquid phase

B : b. Vapor to a liquid phase

C : c. Liquid to a solid phase

D : d. Liquid to a vapor phase

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