The Stefan-Boltzman constant depends on the Surface None of these Temperature Medium TRUE ANSWER : ? YOUR ANSWER : ?
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 tempeature follows __________ law. Logarithmic Parabolic Linear Hyperbolic TRUE ANSWER : ? YOUR ANSWER : ?
For a counter current heat exchanger with Tih = 80°C, T°c = 60°C, T°h = 50°C and Tic = 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 dT/dZ = 0 d²T/dZ² > 0 d²T/dZ² = 0 d²T/dZ² < 0 TRUE ANSWER : ? YOUR ANSWER : ?
Reason for operating an evaporator in multiple effect is to secure Both A and B Decreased steam consumption Increased steam economy Increased capacity TRUE ANSWER : ? YOUR ANSWER : ?
Which of the following is directly concerned with the heat transfer? Grashoff number Sherwood number Strouhal number Euler number TRUE ANSWER : ? YOUR ANSWER : ?
Double pipe heat exchangers are preferably useful, when Requirement of heat transfer area is low A corrosive liquid is to be heated Overall heat transfer co-efficient is very high High viscosity liquid is to be cooled TRUE ANSWER : ? YOUR ANSWER : ?
A long iron rod initially at a temperature of 20°C has one end dipped in boiling water (100°C) at time, t = 0. The curved surface of the rod is insulated so that heat conduction is one dimensional in the axial direction. The temperature at a distance 100 mm from the dipped end becomes 40°C at time, t = 200 s. The same temperature is achieved at a distance of 200 mm from the dipped end at time t = 800 s t = 356 s t = 400 s t = 283 s TRUE ANSWER : ? YOUR ANSWER : ?
Steady state one dimensional heat flow by conduction as given by Fourier's low does not assume that Material is anisotropic There is no internal heat generation Constant temperature gradient exists Boundary surfaces are isothermal TRUE ANSWER : ? YOUR ANSWER : ?
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. 10 minutes 40 minutes 5 minutes 20 minutes TRUE ANSWER : ? YOUR ANSWER : ?