A. Brick
B. Air
C. Water
D. Silver
Correct Answer: Silver ✔
Last Updated: March 03, 2019
Related MCQs
- Circulation pump is located below the evaporator to__________?
- Economy of an evaporator is influenced by the__________?
- ‘Fouling factor’ used in the design of a multipass shell and tube heat exchanger is a__________?
- At Pr > 1, conduction in an ordinary fluid flowing through a heated pipe is limited to the__________?
- Film boiling occurs at __________ pressure?
- Choose the most important factor on which the heat conducted through a wall in a unit time will depend on ?
- Thickness of thermal boundary layer is more compared to that of hydrodynamic boundary layer, when the value of Prandtl number is__________?
- Double pipe heat exchangers are preferably useful, when__________?
- With increase in the distance between the heat source and the object receiving the heat, the radiation heat transfer ?
- For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally ?
- For a counter current heat exchanger with Ti h = 80°C, T°c = 60°C, T°h = 50°C and Ti c = 30°C, and the temperature difference between the two streams being the same everywhere along Z, the direction of flow of hot fluid. The temperature profile should satisfy__________?
- Heat flux through several resistances in series in analogous to the current flowing through several__________?
- At what value of Prandtl number, the hydrodynamic and thermal boundary layers of a fluid flowing over a heated plate will be identical ?
- Heat transfer by natural convection is enhanced in system with__________?
- Reynold’s analogy states that (where, St = Stanton number f = friction factor) ?
- A dephlegmator is a__________?
- Film boiling is usually not desired in commercial equipments, because__________?
- The advantage of backward feed multiple effect evaporators over forward feed units is that__________?
- In case of a multipass shell and tube heat exchanger, providing a baffle on the shell side __________ the heat transfer rate?
- With the increase of temperature, the Col-burn jH factor__________?
- Electromagnetic radiations propagate in vacuum with a velocity of __________ metre/second?
- In a heat exchanger, floating head is provided to__________?
- Which of the following accessories is provided in the vapor line of an evaporator for removing the entrained liquid ?
- The equivalent diameter for pressure drop is __________ that for heat transfer?
- As the difference between the wall temperature and bulk temperature increases, the boiling heat transfer co-efficient ?
- Fouling factor__________?
- If the baffle spacing in a shell and tube heat exchanger increases, then the Reynolds number of the shell side fluid__________?
- The unit of heat transfer co-efficient in SI unit is__________?
- Which type of heat exchanger is preferred for heavy heat loads ?
- With increase in porosity, the thermal conductivity of a solid substance__________?
- Vacuum is generally maintained in the vapour space of an evaporator mainly to__________?
- The number of kg vaporised per kg of steam fed to the evaporator is defined as__________?
- 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?
- Which of the following is unimportant in forced convection ?
- Steam consumption in kg/hr in case of an evaporator is given by (where, C & E are capacity the economy of the evaporator respectively) ?
- Dittus-Boelter equation cannot be used for molten metals mainly due to its very low__________?
- The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K = 0.04 W/m.°K and thickness 0.16m is 10 W/m2. The temperature of the inside wall is – 5°C. The outside wall temperature is__________?
- In a multipass shell and tube heat exchanger, tube side return pressure loss is equal to __________ the velocity head?
- Heat produced when a steady state current, I passes through an electrical conductor having resistance, ‘R’ is__________?
- The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by__________?
- Fourier’s law applies to the heat transfer by__________?
- As per Kirchoff‟s law, the ratio of the total radiating power to the absorptivity of a body depends on the__________?
- When vaporisation takes place directly at the heating surface, it is called__________?
- Thermal conductivity of a conducting solid material depends upon its__________?
- Extended heat transfer surface like fins are used to increase the heat transfer rate. Fin efficiency is defined as the ratio of heat transferred across the fin surface to the theoretical heat transfer across an equal area held at the__________?
- The actual temperature drop across the heating surface in an evaporator depends on the__________?
- Heat flux is the time rate of heat transfer per unit__________?
- The steam ejector is used 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__________?
- Which of the following is generally considered as opaque surface towards radiations ?
- Fourier’s law of heat conduction applies to __________ surfaces?