A. Absorb or emit
B. Refract
C. Reflect
D. Both B. & C.
Correct Answer: D. Both B. & C. ✔
Last Updated: March 03, 2019
Related MCQs
- An equipment which converts the latent or sensible heat of one fluid into the latent heat of vaporisation of another, is called a__________?
- Fresh orange juice contains 12% (by weight) solids and the rest water 90% of the fresh juice is sent to an evaporator to remove water and subsequently mixed with the remaining 10% of fresh juice. The resultant product contains 40% solids. The kg of water removed from 1 kg fresh juice is__________?
- Sensible heat absorbed by 1 lb of water when it is heated from 32 to 212°F may be around __________ BTU?
- Stefan’s block body radiation law can also be derived from __________ law?
- What is the geometric mean of two heat transfer areas A1 and A2 ?
- The ratio of velocity head to tube side return loss in case of a multipass shell and tube heat exchanger is __________?
- Which has the lowest Prandtl number ?
- In case of heat flow by conduction for a cylindrical body with an internal heat source, the nature of temperature distribution is__________?
- Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because__________?
- ‘Duhring’s plot’ is of use in__________?
- View factor is important in heat transfer by__________?
- Forced circulation evaporators are normally used for concentrating liquids having __________?
- The equation, Nst = f/2, is the __________ analogy?
- Which of the following is directly concerned with the heat transfer ?
- The thermal boundary layer at NPr > 1 ?
- Nucleate boiling is promoted __________?
- At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe ?
- 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 __________?
- Cpμ/K is termed as the __________ number?
- In a single evaporator system, the steam economy __________ by creating vacuum in the evaporator?
- In case of a super-cooled solution, which is on the verge of crystallisation, the free energy of the solution as compared to that of the solid is __________?
- Maximum heat transfer rate is obtained in __________ flow?
- Resistance to heat flow by conduction is proportional to (where, t & ρ are thickness & density of the material respectively and A = area normal to the direction of heat flow.) ?
- In a shell and tube heat exchanger, floating head is used for __________?
- Dittus-Boelter equation used for the determination of heat transfer co-efficient is valid __________?
- With increase in temperature, the total emissivity of conductors__________?
- A multiple effect evaporator as compared to a single effect evaporator of the same capacity has __________?
- Which is the best tube arrangement (in a shell and tube heat exchanger) if the fluids are clean and non-fouling ?
- “The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium”. This is __________ law?
- In a forward feed multiple effect evaporator, the pressure is __________?
- For a liquid in laminar flow through a very long tube, when the exit fluid temperature approaches the wall temperature, the equation to be used is__________?
- The non-dimensional temperature gradient in a liquid at the wall of a pipe is the __________?
- The film co-efficient between condensing vapour and metal wall increases with __________?
- With increase in temperature, the thermal conductivity of most liquids__________?
- In a shell and tube heat exchanger, putting a longitudinal baffle across the shell, forces the shell side fluid to pass __________ through the heat exchanger ?
- The driving potential for the crystal growth during crystallisation is the __________ of the solution?
- Heat flux, as defined in heat flow is analogous to __________ in electricity flow?
- Conductance is given by (where, x = thickness, A = heat flow area, K = thermal conductivity.)?
- LMTD can’t be used as such without a correction factor for the__________?
- Heat sensitive materials can be concentrated in an evaporator employing__________?
- For what value of Prandtl number, St = f/2 ?
- In a heat exchanger, the rate of heat transfer from the hot fluid to the cold fluid__________?
- Grashoff number is given by__________?
- If the thermal conductivity of a wall material is independent of temperature, the steady state temperature distribution in the very large thin plane wall having steady, uniform surface temperature follows __________ law?
- Which of the following is the most widely used heat insulating material for pipelines carrying steam ?
- Evaporator tubes are generally__________?
- In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is __________ the outlet temperature of the cold fluid?
- Critical value of the __________ number governs the transition from laminar to turbulent flow in free convection heat transfer?
- Fluid motion in the natural convection heat transfer between a solid surface and a fluid in contact with it, results from the__________?
- Reason for operating an evaporator in multiple effects is to secure __________?
- All analogy equations connecting friction factor and heat transfer co-efficient apply only to __________?