A. Re and Pr
B. Re and Gr
C. Pr and Gr
D. Re and Sc
Correct Answer: Re and Pr ✔
Last Updated: March 03, 2019
Related MCQs
- In a shell and tube type heat exchanger, the floating tube bundle heat arrangement is used__________?
- The Stefan-Boltzmann constant depends on the__________?
- For large heat transfer area requirement, shell and tube heat exchanger is preferred, because it__________?
- A body cools down from 75°C to 70°C in 10 minutes. It will cool down from 70° C to 65° C in __________ minutes?
- Electro-magnetic spectrum range, which is important for radiation varies from __________ microns?
- In a gas-liquid shell and tube heat exchanger, the__________?
- In a shell and tube heat exchanger, square pitch compared to triangular pitch__________?
- Planck’s distribution law is valid for __________ bodies?
- Steam trap is used to__________?
- LMTD for counter-flow and parallel flow heat exchanger will be the same, when the__________?
- Vent pipes are provided in a condenser to __________?
- The advantage of using a 1 – 2 shell and tube heat exchanger over a 1 – 1 shell and tube heat exchanger is__________?
- The equation, Nst = (f/2)/[1 + 5 (Npr – 1) √(f/2)], corresponds to __________ analogy?
- Open pan evaporators are preferred to be used, when the solution to be concentrated is__________?
- When warm and cold liquids are mixed, the heat transfer is mainly by__________?
- At constant temperature, the thermal conductivities of gases __________ with rise in pressure?
- A single pass air heater is connected to a two pass unit. For the air flow rate and other conditions remaining the same, the film heat transfer co-efficient for air will vary in the ratio of__________?
- It is not preferable to use superheated steam in evaporators, because of its very__________?
- __________ heat exchanger is used for chilling oil to be dewaxed?
- If heat transfer rate varies with the time, it is termed as__________?
- 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__________?
- The absorptivity of a body is equal to its emissivity __________?
- A perfect black body is a perfect __________ of radiation?
- jH factor for heat transfer depends upon the __________ number?
- The actual temperature drop across the heating surface of an evaporator depends on the__________?
- Heat transfer by conduction in the turbulent core of a fluid flowing through a heated pipe is negligible, if the value of Prandtl number is__________?
- Indirect contact heat exchangers are preferred over direct contact heat exchangers, because__________?
- Which of the following has the lowest overall heat transfer co-efficient ?
- Forced circulation evaporators are useful for the concentration of viscous, salting and scale forming liquors. Which of the following is a forced circulation evaporator ?
- The absorptivity of a grey body at a given temperature __________ with increasing wavelength of radiation?
- In case of heat transfer by conduction in a hollow cylinder, __________ mean area is used to calculate the heat transfer rate?
- The characteristic dimensionless groups for heat transfer to a fluid flowing through a pipe in laminar flow are__________?
- One kilogram of water at 0°C is changed to superheated steam of one atm pressure and 300° C. The major heat consumption in the process will be to__________?
- A sphere of radius ‘R1’ is enclosed in a sphere of radius ‘R2’. The view (or shape) factor for radiative heat transfer of the outer sphere with respect to the inner sphere is __________?
- Solid angle subtended by the finite surface at the radiating element is__________?
- Corrosiveness of steam condensate is due to the presence of__________?
- Minimum recommended baffle spacing in a shell and tube heat exchanger is about (where, D = shell diameter)?
- Tube expansion allowances exist in __________ heat exchanger?
- Multiple effect evaporation accounts for__________?
- A black body does not __________ radiation?
- 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__________?