A. Clean and dirt free
B. Smooth clean
C. Contaminated cooling
D. Polished
Correct Answer: Contaminated cooling ✔
Last Updated: March 03, 2019
Related MCQs
- Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is__________?
- The type of liquor circulation system to be ‘ employed in evaporators (viz. natural or forced circulation) is determined mainly by the __________ of the liquid?
- For a given ambient air temperature with increase in the thickness of insulation of a hot cylindrical pipe, the rate of heat loss from the surface would ?
- In a backward feed multiple effect evaporator __________ ?
- The sum of reflectivity and absorptivity for an opaque body is equal to__________?
- Steam is routed through the tube in case of a __________ evaporator?
- Multiple effect evaporation is generally recommended, when the__________?
- 1 BTU/hr.ft.°F is equal to __________ kcal/hr. m.°C?
- A __________ surface has the maximum thermal emissivity out of the following ?
- A hollow sphere and a solid sphere of the same material and equal radii are heated to the same temperature. In this case ?
- Which of the following has the highest thermal conductivity ?
- 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__________?