Heat and Mass Transfer According to Stefan's law, the total radiation from a black body per second per unit area is proportional to T5 T2 Absolute temperature T T5 T2 Absolute temperature T ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The ratio of the thickness of thermal boundary layer to the thickness of hydrodynamic boundary layer is equal to (Prandtl number) n, where n is equal to 1 -1 =-1/3 =-2/3 1 -1 =-1/3 =-2/3 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The heat transfer by conduction through a thick cylinder (Q) is given by (where T₁ = Higher temperature, T₂ = Lower temperature, r₁ = Inside radius, r₂ = Outside radius, l = Length of cylinder, and k = Thermal conductivity) Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Film coefficient is defined as the ratio of Thickness of film of fluid to the temperature drop through the films of fluids Temperature drop through the films of fluids to the thickness of film of fluids Thickness of film of fluid to the thermal conductivity Thermal conductivity to the equivalent thickness of the film of fluid Thickness of film of fluid to the temperature drop through the films of fluids Temperature drop through the films of fluids to the thickness of film of fluids Thickness of film of fluid to the thermal conductivity Thermal conductivity to the equivalent thickness of the film of fluid ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer A grey body is one whose absorptivity Varies with temperature Does not vary with temperature and. wavelength of the incident ray Is equal to its emissivity Varies with wavelength of the incident ray Varies with temperature Does not vary with temperature and. wavelength of the incident ray Is equal to its emissivity Varies with wavelength of the incident ray ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Two long parallel surfaces each of emissivity 0.7 are maintained at different temperatures and accordingly have radiation heat exchange between them. It is desired to reduce 75% of the radiant heat transfer by inserting thin parallel shields of emissivity 1 on both sides. The number of shields should be Three Four One Two Three Four One Two ANSWER DOWNLOAD EXAMIANS APP
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