ISRO SC/ENG 2012

1) Water is boiled at 1 x 10⁵ Pa pressure in a coffee maker equipped with an immersion-type electric heating element. The coffee maker initially contains 1 kg of water. Once boiling started, it is observed that half of the water in the coffee maker evaporated in 18 minutes. If the heat loss from the coffee maker is negligible, the power rating of the heating element is

A. 0.90 KW
B. 1.52 KW
C. 1.05 KW
D. 1.24 KW

  Get Solution

2) An adiabatic heat exchanger is used to heat cold water at 15⁰C entering at a rate of 5 kg/s by hot air at 90⁰C entering also at rate of 5 kg/s. If the exit temperature of hot air is 20⁰C, the exit temperature of cold water is

A. 27⁰C
B. 32⁰C
C. 85⁰C
D. 90⁰C

  Get Solution

3) Log Mean Area 'A' can be given as

A. (log A₂ - log_{1) / (A2 - A1)
B. (A2 - A1) / (log A2 - log1)
C. (log A2 - log1) / log (A2/A1))
D. None}

4) Nusselt number is the ratio of

A. Convective and Conductive resistances
B. Conductive and Convective resistances
C. Wall heat transfer rate to mass heat flow rate
D. Kinetic viscosity to thermal diffusivity