Heat Transfer — Part 2 MCQs with Explanations

Radiation is the correct answer to “View factor is important in heat transfer by”. This question is standard in competitive examination syllabi for Heat Transfer.

Conduction is the correct answer to “Thermal diffusivity is the most important in heat transfer by”. This question is standard in competitive examination syllabi for Heat Transfer.

U-tube is the correct answer to “Tube expansion allowances exist in __________ heat exchanger.”. This question is standard in competitive examination syllabi for Heat Transfer.

$$\frac{{\text{D}}}{5}$$ and D is the correct answer to “In case of a shell and tube heat exchanger, the minimum and maximum baffle spacing is respectively (where, D = inside diameter of the shell)”. This question is standard in competitive examination syllabi for Heat Transfer.

Natural convection is the correct answer to “Mode of heat transfer involved in the cooling of air cooled internal combustion engine is”. This question is standard in competitive examination syllabi for Heat Transfer.

Boiling point elevations is the correct answer to “Economy of a multiple effect evaporator is not influenced much by the”. This question is standard in competitive examination syllabi for Heat Transfer.

Reynolds number for the flow involved is < 2100 is the correct answer to “Heat transfer co-efficient equation for forced convection, Nu = 0.023 R e 0.8 . P r n , is not valid, if the value of”. This question is standard in competitive examination syllabi for Heat Transfer.

Same in either A, B or C is the correct answer to “LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counterflow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface area required is the least in the __________ flow.”. This question is standard in competitive examination syllabi for Heat Transfer.

Both A and B is the correct answer to “In evaporators, lowering the feed temperature”. This question is standard in competitive examination syllabi for Heat Transfer.

180 is the correct answer to “Latent heat absorbed by 1 lb of water at 212°F, when it is changed to steam at 212°F, may be around __________ BTU.”. This question is standard in competitive examination syllabi for Heat Transfer.

180 is the correct answer to “Sensible heat absorbed by 1 lb of water when it is heated from 32 to 212°F may be around __________ BTU.”. This question is standard in competitive examination syllabi for Heat Transfer.

Mixed convection (both free and forced) is the correct answer to “When the ratio of the Grashoff number and to the square of Reynolds number is one, the dominant mechanism of heat transfer is”. This question is standard in competitive examination syllabi for Heat Transfer.

Increases is the correct answer to “With increase in temperature, the thermal conductivity of non-metallic amorphous solids”. This question is standard in competitive examination syllabi for Heat Transfer.

Zero is the correct answer to “What is the thermal conductivity of a perfect heat insulator”. This question is standard in competitive examination syllabi for Heat Transfer.

None of these is the correct answer to “Heat transfer by radiation between two bodies at T 1 & T 2 and in an ambient temperature of T a °C depends on”. This question is standard in competitive examination syllabi for Heat Transfer.

When heat transfer area required is very low, i.e (100 - 200 ft2) is the correct answer to “Double pipe heat exchangers are used”. This question is standard in competitive examination syllabi for Heat Transfer.

All of the above is the correct answer to “Loss of heat from untagged steam pipe to the ambient air is by”. This question is standard in competitive examination syllabi for Heat Transfer.

Straight line is the correct answer to “A hot liquid is kept in a big room. The logorithm of the numerical value of the temperature difference between the liquid and the room is plotted against time. The plot will be very nearly a/an”. This question is standard in competitive examination syllabi for Heat Transfer.

Less is the correct answer to “The equivalent diameter for the annulus of a double pipe heat exchanger, whose inner pipe has fins on the outside is __________ compared to the same size pipes without fins.”. This question is standard in competitive examination syllabi for Heat Transfer.

Vertical heat exchanger with steam on shell side is the correct answer to “Steam is to be condensed in a shell and tube heat exchanger, 5 m long with a shell diameter of 1 m. Cooling water is to be used for removing the heat. Heat transfer co-efficient for the cooling water, whether on shell side or tube side is the same. The best arrangement is”. This question is standard in competitive examination syllabi for Heat Transfer.

Increase the shell side heat transfer co-efficient is the correct answer to “Baffles in the shell side of a shell and tube heat exchanger”. This question is standard in competitive examination syllabi for Heat Transfer.

2 is the correct answer to “If all the conditions and dimensions are same, then the ratio of velocity through the tubes of a double pass heat exchanger to that through the single pass heat exchanger is”. This question is standard in competitive examination syllabi for Heat Transfer.

Linear is the correct answer to “Temperature profile in steady state heat transfer is”. This question is standard in competitive examination syllabi for Heat Transfer.

165.4 is the correct answer to “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 -2 is”. This question is standard in competitive examination syllabi for Heat Transfer.

And the wall are proportional to individual resistances is the correct answer to “In case of a multipass shell and tube heat exchanger, the temperature drop in the fluid”. This question is standard in competitive examination syllabi for Heat Transfer.

70 is the correct answer to “Three material A, B and C of equal thick-nes and of thermal conductivity of 20, 40 & 60 kcal/hr. m. °C respectively are joined together. The temperature outside of A and C are 30°C and 100°C respectively. The interface between B and C will be at a temperature of __________ °C.”. This question is standard in competitive examination syllabi for Heat Transfer.

0 is the correct answer to “In a 1-1 cocurrent heat exchanger, if the tube side fluid outlet temperature is equal to the shell side fluid outlet temperature, then the LMTD is”. This question is standard in competitive examination syllabi for Heat Transfer.

Film is the correct answer to “When vaporisation takes place through a blanketting film of gas, the phenomenon is termed as __________ boiling.”. This question is standard in competitive examination syllabi for Heat Transfer.

Boiling point is the correct answer to “Boiling point elevation for a strong and concentrated solution is found by Duhring's rule, which states that at the same pressure, the boiling point of a solution is a linear function of the __________ of pure water.”. This question is standard in competitive examination syllabi for Heat Transfer.

Viscosity is the correct answer to “The type of liquor circulation system to be ' employed in evaporators (viz. natural or forced circulation) is determined mainly by the __________ of the liquid.”. This question is standard in competitive examination syllabi for Heat Transfer.

All of the above is the correct answer to “Resistance to heat flow by conduction is proportional to (where, t & $$\rho $$ are thickness & density of the material respectively and A = area normal to the direction of heat flow.)”. This question is standard in competitive examination syllabi for Heat Transfer.

Decreased capacity is the correct answer to “Increasing the liquor level in the evaporator results in the”. This question is standard in competitive examination syllabi for Heat Transfer.

12 is the correct answer to “A wall has two layers of materials A and B; each made of a different material. Both the layers have the same thickness. The thermal conductivity of materialA is twice that of B. Under the equilibrium, the temperature difference across the wall is 36°C. The temperature difference across the layer A is __________ °C.”. This question is standard in competitive examination syllabi for Heat Transfer.

< 0.75 is the correct answer to “It is not recommended to use a 1-2 shell and tube heat exchanger for a particular heat duty, whenever the LMTD correction factor is”. This question is standard in competitive examination syllabi for Heat Transfer.

Least at the outlet of the last effect is the correct answer to “In a forward feed multiple effect, the pressure build up will be”. This question is standard in competitive examination syllabi for Heat Transfer.

Remain unchanged is the correct answer to “In a co-current double pipe heat exchanger used for condensing saturated steam over the inner tube, if the entrance and exit conditions of the coolant are interchanged, then the rate of condensation will”. This question is standard in competitive examination syllabi for Heat Transfer.

Increases is the correct answer to “With increase in temperature, the thermal conductivity of a gas”. This question is standard in competitive examination syllabi for Heat Transfer.

Decreases is the correct answer to “With increase in temperature, the thermal conductivity of steel”. This question is standard in competitive examination syllabi for Heat Transfer.

Transmits is the correct answer to “A diathermaneous substance __________ the thermal radiation completely.”. This question is standard in competitive examination syllabi for Heat Transfer.

Increased economy is the correct answer to “For a cold dilute feed to produce thick viscous liquor, backward feeding as compared to forward feeding results in”. This question is standard in competitive examination syllabi for Heat Transfer.