What is the thermal conductivity of a perfect heat insulator ?
What is the thermal conductivity of a perfect heat insulator ?
A. Zero
B. One
C. ∞
D. Between 0 and ∞
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The overall heat transfer co-efficient for a shell and tube heat exchanger for clean surfaces is U0 = 400 W/m2.K. The fouling factor after one year of operation is found to be hd0 = 2000 W/m2.K. The overall heat transfer co-efficient at this time is _____________________?
The overall heat transfer co-efficient for a shell and tube heat exchanger for clean surfaces is U0 = 400 W/m2.K. The fouling factor after one year of operation is found to be hd0 = 2000 W/m2.K. The overall heat transfer co-efficient at this time is _____________________?A. 1200 W/m2.K
B. 894 W/m2.K
C. 333 W/m2.K
D. 287 W/m2.KRadiation heat losses from satisfactorily insulated high pressure boiler may be about _____________ percent?
Radiation heat losses from satisfactorily insulated high pressure boiler may be about _____________ percent?A. 1
B. 7
C. 18
D. 26All analogy equations connecting friction factor and heat transfer co-efficient apply only to ___________________?
All analogy equations connecting friction factor and heat transfer co-efficient apply only to ___________________?A. Wall or skin friction
B. Form friction
C. Both A. and B.
D. Turbulent flowIn a single effect evaporator, the economy is________________?
In a single effect evaporator, the economy is________________?A. 1
B. < 1
C. > 1
D. None of theseWhich of the following is generally considered as opaque surface towards radiations ?
Which of the following is generally considered as opaque surface towards radiations ?A. Gases
B. Solids
C. Liquids
D. Both B. and C.In case of a multipass shell and tube heat exchanger, providing a baffle on the shell side ______________ the heat transfer rate?
In case of a multipass shell and tube heat exchanger, providing a baffle on the shell side ______________ the heat transfer rate?A. Increases
B. Decreases
C. Does not affect
D. May increase or decrease, depends on the type of baffle