Heat and Mass Transfer Depending on the radiating properties, a body will be opaque when X = 0, a + p = 1 P = 0, x = 1 and a = 0 P = 0, x = 0 and a = 1 P=1, x = 0 and a = 0 X = 0, a + p = 1 P = 0, x = 1 and a = 0 P = 0, x = 0 and a = 1 P=1, x = 0 and a = 0 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Film coefficient is defined as the ratio of 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 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 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 = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The thermal diffusivities for gases are generally Dependent on the viscosity More than those for liquids Less than those for liquids More than those for solids Dependent on the viscosity More than those for liquids Less than those for liquids More than those for solids ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer An electric cable of aluminium conductor (k = 240 W/mK) is to be insulated with rubber (k = 0.15 W/mK). The cable is to be located in air (h = 6 W/m²). The critical thickness of insulation will be 40 mm 160 mm 25 mm 800 mm 40 mm 160 mm 25 mm 800 mm ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer According to Prevost theory of heat exchange It is impossible to transfer heat from low temperature source to t high temperature source Heat transfer by radiation requires no medium All bodies above absolute zero emit radiation Heat transfer in most of the cases takes place by combination of conduction, convection and radiation It is impossible to transfer heat from low temperature source to t high temperature source Heat transfer by radiation requires no medium All bodies above absolute zero emit radiation Heat transfer in most of the cases takes place by combination of conduction, convection and radiation ANSWER DOWNLOAD EXAMIANS APP
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