160 Important Heat And Mass Transfer MCQ Question and Answer | PDF Free Download
1.Which of the following is a case of steady state heat transfer?
- AI.C. engine
- BAir preheaters
- CHeating of building in winter
- DNone of the above
2.When absorptivity (α) = 1, reflectivity (ρ) = 0 and transmissivity (τ) = 0, then the body is said to be a
- ABlack body
- BGrey body
- COpaque body
- DWhite body
6.The unit of Stefan Boltzmann constant is
- Awatt/cm3 K
- Bwatt/cm4 K
- Cwatt2/cm K⁴
- Dwatt/cm2 K⁴
7.According to Newton's law of cooling, the heat transfer from a hot body to a cold body is
- ADirectly proportional to the surface area
- BDirectly proportional to the difference of temperatures between the two bodies
- CEither (A) or (B)
- DBoth (A) and (B)
8.Fourier's law of heat conduction is valid for
- AOne dimensional cases only
- BTwo dimensional cases only
- CThree dimensional cases only
- DRegular surfaces having non-uniform temperature gradients
9.The process of heat transfer from one particle of the body to another by the actual motion of the heated particles, is called
- AConduction
- BConvection
- CRadiation
- DNone of these
10.The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles due to difference of density caused by temperature of the particle is known as
- AConduction
- BFree convection
- CForced convection
- DRadiation
14.If the energy radiated per second per sq. cm. of the surface for wave lengths lying between λ, and λ + dλ is represented by (eλ.dλ), then eλ is called
- AAbsorptive power
- BEmissive power
- CEmissivity
- DNone of these
15.The energy distribution of an ideal reflector at higher temperatures is largely in the range of
- AShorter wavelength
- BLonger wavelength
- CRemain same at all wavelengths
- DWavelength has nothing to do with it
16.In counter flow heat exchangers
- ABoth the fluids at inlet (of heat exchanger where hot fluid enters) are in their coldest state
- BBoth the fluids at inlet are in their hottest state
- CBoth the fluids at exit are in their hottest state
- DOne fluid is in hottest state and other in coldest state at inlet
17.In counter current flow heat exchanger, the logarithmic temperature difference between the fluids is ________ as compared to parallel flow heat exchanger.
- ASame
- BLess
- CGreater
- DNone of these
18.Fourier's law of heat conduction is (where Q = Amount of heat flow through the body in unit time, A = Surface area of heat flow, taken at right angles to the direction of heat flow, dT = Temperature difference on the two faces of the body, dx = Thickness of the body, through which the heat flows, taken along the direction of heat flow, and k = Thermal conductivity of the body)
- Ak. A. (dT/dx)
- Bk. A. (dx/dT)
- Ck. (dT/dx)
- Dk. (dx/dT)
19.Upto the critical radius of insulation
- AAdded insulation will increase heat loss
- BAdded insulation will decrease heat loss
- CConvective heat loss will be less than conductive heat loss
- DHeat flux will decrease
20.The product of Reynolds number and Prandtl number is known as
- AStanton number
- BBiot number
- CPeclet number
- DGrashoff number