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 = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Thermal conductivity of glass wool varies from sample to sample because of variation in Porosity All of these Composition Density Porosity All of these Composition Density ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The ratio of Nusselt number and the product of Reynold's number and Prandtl number is equal to Stanton number Peclet number Biot number Grashoff number Stanton number Peclet number Biot number Grashoff number ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Kirchhoff's law states that None of these The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body The total radiation from a black body per second per unit area is directly proportional to the fourth power of the absolute temperature The wave length corresponding to the maximum energy is proportional to the absolute temperature None of these The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body The total radiation from a black body per second per unit area is directly proportional to the fourth power of the absolute temperature The wave length corresponding to the maximum energy is proportional to the absolute temperature ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Film coefficient is defined as Inside diameter of tube Film coefficient × Inside diameter Thermal conductivity Thermal conductivity Molecular diffusivity of momentum Thermal diffusivity Equivalent thickness of film Thermal conductivity Equivalent thickness of film Specific heat × Viscosity Film coefficient × Inside diameter Thermal conductivity Thermal conductivity Molecular diffusivity of momentum Thermal diffusivity Equivalent thickness of film Thermal conductivity Equivalent thickness of film Specific heat × Viscosity ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer A perfect black body is one which Absorbs heat radiations of all wave lengths falling on it Reflects all heat Is black in colour Transmits all heat radiations Absorbs heat radiations of all wave lengths falling on it Reflects all heat Is black in colour Transmits all heat radiations ANSWER DOWNLOAD EXAMIANS APP
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