GATE-CH-1992-5-c-ht-2mark

To initiate boiling of a liquid, the temperature of the heated surface, if smooth will be ––––- than for a commercial or a roughened surface.

• higher

• lower

GATE-CH-1999-1-14-ht-1mark

As the difference between the wall temperature and bulk temperature increases, the boiling heat transfer coefficient

• continues to increase

• continues to decrease

• goes through a minimum

• goes through a maximum

GATE-CH-2005-14-ht-1mark

An electrically heated element is submerged in a pool of water at its saturation temperature. As the temperature of the element increases, the maximum heat transfer coefficient is observed

• in the free convection regime

• between nucleate boiling and partial nucleate boiling mixed with unstable film boiling regimes

• in the incipient nucleate boiling regime

• in the stable film boiling regime without significant radiation effects

GATE-CH-2013-17-ht-1mark

In a pool boiling experiment, the following phenomena were observed.

• [P.] Natural convection
• [Q.] Film boiling
• [R.] Transition boiling
• [S.] Nucleate boiling

What was the CORRECT sequence of their occurrence?

• P, Q, R, S

• S, R, Q, P

• Q, R, P, S

• P, S, R, Q

GATE-CH-2017-41-ht-2mark

In nucleate boiling, the pressure inside a bubble is higher than the pressure of the surrounding liquid. Assuming that both the liquid and vapor are saturated, the temperature of the liquid will always be

• at 100^oC

• lower than the temperature of the vapor

• equal to the temperature of the vapor

• higher than the temperature of the vapor