A. Black
B. White lead
C. Grey
D. Light cream
Related Mcqs:
- _______________ paint has the maximum absorption coefficient ?
A. Black
B. Yellow
C. White
D. Grey - If h1 = inner film co-efficient and /h2 = outer film co-efficient, then the overall heat transfer co-efficient is________________?
A. Always less than h1
B. Always between h1 and h2
C. Always higher than h2
D. Dependent on metal resistance - 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 - 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.K - The film co-efficient is decreased due to the presence of non-condensing gases in the vapors. The film co-efficient of superheated vapor as compared to that of saturated vapor is___________________?
A. More
B. Less
C. Some
D. Either more or less; depends on the nature of vapor - For turbulent flow in a tube, the heat transfer co-efficient is obtained from the Dittus- Boelter correlation. If the tube diameter is halved and the flow rate is doubled, then the heat transfer co-efficient will change by a factor of________________?
A. 1
B. 1.74
C. 6.1
D. 37 - Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by the tube length/diameter ratio, if the flow is in the _____________ zone?
A. Laminar
B. Transition
C. Both A & B
D. Highly turbulent - The inner wall of a furnace is at a temperature of 700°C. The composite wall is made of two substances, 10 and 20 cm thick with thermal conductivities of 0.05 and 0.1 W.m-1.°C- 1 respectively. The ambient air is at 30°C and the heat transfer co-efficient between the outer surface of wall and air is 20 W.m-2.°C-1. The rate of heat loss from the outer surface in W.m-2is__________________?
A. 165.4
B. 167.5
C. 172.5
D. 175 - The thermal efficiency of a reversible heat engine operating between two given thermal reservoirs is 0.4. The device is used either as a refrigerator or as a heat pump between the same reservoirs. Then the coefficient of performance as a refrigerator (COP)R and the co-efficient of performance as a heat pump (COP)HP are _______________?
A. (COP)R = (COP)HP = 0.6
B. (COP)R = 2.5; (COP)HP = 1.5
C. (COP)R = 1.5; (COP)HP = 2.5
D. (COP)R = (COP)HP = 2.5
