Heat and Mass Transfer If the temperature of a solid surface changes form 27°C to 627°C, then its emissive power changes in the ratio of 9 81 3 270 9 81 3 270 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 Thermal conductivity to the equivalent thickness of the film of fluid Thickness of film of fluid to the thermal conductivity 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 Thermal conductivity to the equivalent thickness of the film of fluid Thickness of film of fluid to the thermal conductivity ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Thermal diffusivity is a All of these Function of temperature Physical property of a substance Dimensionless parameter All of these Function of temperature Physical property of a substance Dimensionless parameter ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer A designer chooses the values of fluid flow rates and specific heats in such a manner that the heat capacities of the two fluids are equal. A hot fluid enters the counter flow heat exchanger at 100°C and leaves at 60°C. A cold fluid enters the heat exchanger at 40°C. The mean temperature difference between the two fluids is 60°C 20°C 66.7°C 40°C 60°C 20°C 66.7°C 40°C 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 = [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)] ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Cork is a good insulator because it has Atoms colliding frequency Free electrons Low density Porous body Atoms colliding frequency Free electrons Low density Porous body ANSWER DOWNLOAD EXAMIANS APP
EXAMIANS