Heat and Mass Transfer Absorptivity of a body will be equal to its emissivity At all temperatures When system is under thermal equilibrium At one particular temperature At critical temperature At all temperatures When system is under thermal equilibrium At one particular temperature At critical temperature ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Thermal diffusivity of a substance is given by (where h = Thermal diffusivity, ρ = Density of substance, S = Specific heat, and k = Thermal conductivity) h = k/ ρS h = ρS/k h = S/ρk h = kρ/S h = k/ ρS h = ρS/k h = S/ρk h = kρ/S ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer 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 = tm = (Δt1 - Δt2) loge (Δt1/Δt2) tm = loge (Δt1 - Δt2)/ Δt1/Δt2 tm = (Δt1 - Δt2)/ loge (Δt1/Δt2) tm = loge (Δt1/Δt2)/ (Δt1 - Δt2) tm = tm = (Δt1 - Δt2) loge (Δt1/Δt2) tm = loge (Δt1 - Δt2)/ Δt1/Δt2 tm = (Δt1 - Δt2)/ loge (Δt1/Δt2) tm = loge (Δt1/Δt2)/ (Δt1 - Δt2) ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Thermal conductivity of air with rise in temperature Increases Remain constant Decreases May increase or decrease depending on temperature Increases Remain constant Decreases May increase or decrease depending on temperature ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer In a shell and tube heat exchanger, baffles are provided on the shell side to Provide support for tubes Improve heat transfer All of these Prevent stagnation of shell side fluid Provide support for tubes Improve heat transfer All of these Prevent stagnation of shell side fluid ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The heat transfer from a hot body to a cold body is directly proportional to the surface area and difference of temperatures between the two bodies. This statement is called Newton's law of cooling Newton's law of heating Stefan's law First law of thermodynamics Newton's law of cooling Newton's law of heating Stefan's law First law of thermodynamics ANSWER DOWNLOAD EXAMIANS APP
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