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The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe whose surface temperature remains constant is______________?
Related MCQs
Which characteristic of a fluid is not important in deciding its route in a shell and tube heat exchanger ?
What is the absorptivity of a black body?
Economy of a multiple effect evaporator is not influenced much by the__________?
Asymptotic conditions is reached, when for a fluid flowing in laminar flow through a long tube__________?
In case of evaporators, liquid entrainment results primarily due to__________?
Heat exchangers operating, when the asymptotic range is reached, ?
In counter flow compared to parallel flow, ?
Mode of heat transfer involved in the cooling of air cooled internal combustion engine is__________?
In a single effect evaporator, the economy is__________?
Small scale evaporation is done in a__________?
In a liquid-liquid heat exchanger, for the same process temperature, the ratio of the LMTD in parallel flow to the LMTD in counter flow is always__________?
Low thermal conductivity of heat insulating materials is due to its__________?
Low thermal conductivity of heat insulating materials is due to its__________?
In case of a vertical tube evaporator, with increase in the liquor level, the__________?
The rate of heat transfer is a product of overall heat transfer co-efficient, the difference in temperature and the__________?
Thermal diffusivity is given by__________?
In a forward feed multiple effect, the pressure build up will be__________?
Which of the following has the minimum absorptivity ?
Convective heat transfer, in which heat is transferred by movement of warmed matter is described by__________?
If h1 = inner film co-efficient and /h2 = outer film co-efficient, then the overall heat transfer co-efficient is__________?
In an extended surface heat exchanger, fluid having lower co-efficient__________?
The critical radius ‘r’ of insulation on a pipe is given by__________?
In an interphase heat transfer process, the equilibrium state corresponds to equality of temperature in the two phases, while the condition for equilibrium in an interphase mass transfer process is equality of__________?
A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m2.°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be__________?
Sensible heat of hot industrial flue gases cannot be recovered by a/an__________?
In case of a vertical tube evaporator, with increase in the liquor level, the __________ is increased?
The heat flux in the nucleate boiling regimes is proportional to (where, ΔT = excess temperature) ?
In a multiple effect evaporator, the effect of boiling point elevation is to__________?
Film condensation is promoted on a/an __________ surface?
In a boiling curve, the peak heat flux is called the __________ point?
In case of __________ boiling, the bubbles formed on a submerged hot surface get absorbed in the mass of the liquid?
Nusselt number (for forced convection heat transfer) is a function of the __________ number?
The separation of liquid droplets from the vapor is done by a/an __________ in the evaporators?
For the same heat transfer area and the terminal conditions, the ratio of the capacities of a single effect evaporator to a triple effect evaporator is__________?
In forced circulation, the heating element is injected__________?
According to Reynolds analogy, Stanton number is equal to (where, f = Fanning friction factor) ?
The wavelength at which the maximum monochromatic emissive power occurs for a black body, is (where, T = absolute temperature of the black body)?
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?
A dilute aqueous solution is to be concentrated in an evaporator system. High pressure steam is available. Multiple effect evaporator system is employed, because__________?
In a 1-1 concurrent heat exchanger, if the tube side fluid outlet temperature is equal to the shell side fluid outlet temperature, then the LMTD is__________?
Grashoff number, which is defined as g . β (Ts – T∞) ρ2. L3/μ2, is proportional to the ratio of buoyancy force to __________ force?
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?
Viscous & heat sensitive liquids are concentrated in __________ evaporators?
In case of surface condensers, a straight line is obtained on plotting 1/U vs. __________ on an ordinary graph paper?
Viscosity of gases __________ with increase in temperature?
During crystallisation, formation of crystal can occur in __________ solution only?
When does the heat generated by fluid friction becomes appreciable compared to the heat transferred between the fluids ?
Condensing film co-efficient for steam on horizontal tubes ranges from 5000 to 15000 Kcal/hr.m2.°C. Condensation of vapor is carried out inside the tube in a shell and tube heat exchanger, when the__________?
A cube, sphere & a thin circular plate (all having same mass and made of same material) are all heated to 300°C and allowed to cool in natural air. Which one will cool the slowest ?
A steel sphere of radius 0.1 m at 400°K is immersed in an oil at 300°K. If the centre of the sphere reaches 350°K in 20 minutes, how long will it take for a 0.05 m radius steel sphere to reach the same temperature (at the centre) under identical conditions? Assume that the conductive heat transfer co-efficient is infinitely large ?
Presence of a non-condensing gas in a condensing vapour__________?
The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe whose surface temperature remains constant is______________?
A. 1.66
B. 88.66
C. 3.66
D. Dependent on NRe only
Correct Answer:
3.66
✔
Last Updated:
March 03, 2019