Which of the following property of air does not increase with rise in temperature? Thermal diffusivity Thermal conductivity Density Dynamic viscosity TRUE ANSWER : ? YOUR ANSWER : ?
Total heat is the heat required to Change vapour into liquid Change liquid into vapour Convert water into steam and superheat it Increase the temperature of a liquid or vapour TRUE ANSWER : ? YOUR ANSWER : ?
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 Radiation Forced convection Conduction Free convection TRUE ANSWER : ? YOUR ANSWER : ?
In free convection heat transfer, Nusselt number is function of Grashoff number, Prandtl number and Reynold number Prandtl number and Reynold number Grashoff number and Prandtl number Grashoff number and Reynold number TRUE ANSWER : ? YOUR ANSWER : ?
Unit of thermal conductivity in S.I. units is Option (B) and (C) above W/m °K J/m °K sec J/m² sec TRUE ANSWER : ? YOUR ANSWER : ?
In counter flow heat exchangers One fluid is in hottest state and other in coldest state at inlet Both the fluids at inlet (of heat exchanger where hot fluid enters) are in their coldest state Both the fluids at inlet are in their hottest state Both the fluids at exit are in their hottest state TRUE ANSWER : ? YOUR ANSWER : ?
Thermal conductivity of air with rise in temperature Decreases Increases May increase or decrease depending on temperature Remain constant TRUE ANSWER : ? YOUR ANSWER : ?
The logarithmic mean temperature difference (tm) is given by (where Δt1 and Δt2 are temperature differences between the hot and cold fluids at entrance and exit) tm = loge (Δt1/Δt2)/ (Δt1 - Δt2) tm = (Δt1 - Δt2)/ loge (Δt1/Δt2) tm = tm = (Δt1 - Δt2) loge (Δt1/Δt2) tm = loge (Δt1 - Δt2)/ Δt1/Δt2 TRUE ANSWER : ? YOUR ANSWER : ?
Sensible heat factor is given by (where S.H. = Sensible heat, and L.H. = Latent heat) S.H/(L.H - S.H) (L.H - S.H)/S.H (S.H + L.H) /S.H S.H/(S.H + L.H) TRUE ANSWER : ? YOUR ANSWER : ?
The expression Q = ρ AT4 is called Stefan-Boltzmann equation Fourier equation Joseph-Stefan equation Newton Reichmann equation TRUE ANSWER : ? YOUR ANSWER : ?