Reason for operating an evaporator in multiple effects is to secure ___________________?

For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it__________________?

A. Decreases the pressure drop

B. Decreases the outlet temperature of cooling medium

C. Increases the overall heat transfer coefficient

D. None of these

Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100°C and the inside heat transfer coefficient is „3k/l’. If the wall temperature on the outside is held at 25°C, what is the inside wall temperature in degree centigrade ?

A. 35.5

B. 43.75

C. 81.25

D. 48.25

A graph between _____________ is called Wilson plot?

A. (1/U) Vs. (1/v0.8)

B. (1/v0.8) Vs. U

C. v0.8 Vs . U

D. (1/U) Vs. (1/V)

For a laminar flow of fluid in a circular tube, ‘h1’ is the convective heat transfer co-efficient at velocity ‘V1’. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is________________?

A. 1.26 h1

B. 0.794 h1

C. 0.574 h1

D. 1.741 h1

Fouling factor for a heat exchanger is given by (where, U1 = heat transfer co-efficient of dirty surface U2 = heat transfer co-efficient of clean surface) ?

A. U1 – U2

B. 1/U1 – 1/U2

C. 1/U2 – 1/U1

D. U2 – U1