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

View solution

Q. The phenomenon of stable film boiling is referred to as

View solution

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

View solution

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

View solution

Q. 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

View solution

Q. Fritz criterion is given by

View solution

Q. 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.

View solution

Q. 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

View solution

Q. The heat flux in nucleate boiling varies in accordance with

View solution

Q. In nucleate pool boiling, the heat flux depends on

View solution

Q. Identify the wrong statement with respect to boiling heat transfer?

View solution

Q. 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 * 10⁶ J/kg
σ = 0.0585 N/m

View solution

Q. 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
σ = 0.0533 N/m

View solution

Q. Condensation refers to a change from the

View solution

Q. Condensation process is very common in

(i) Boilers
(ii) Condensers
(iii) Evaporators

Identify the correct statements

View solution

Q. The convective coefficients for condensation usually lie in the range

View solution

Q. Drop wise condensation usually occurs on

View solution

Q. Consider the following statements:

(i) If a condensing liquid does not wet a surface, then drop wise condensation will not take place on it
(ii) Drop wise condensation gives a higher transfer rate than film wise condensation
(iii) Reynolds number of condensing liquid is based on its mass flow rate
(iv) Suitable coating or vapor additive is used to promote film wise condensation

Identify the correct statement

View solution

Q. Depending upon the behavior of condensate up on the cooled surface, the condensation process are classified into how many distinct modes?

View solution

Q. A plate condenser was designed to be kept vertical. How would the condensation coefficient be effected if due to site constraints, it has to be kept at 60 degree to the horizontal?

View solution