Heat and Mass Transfer The total radiation from a black body per second per unit area is ________ fourth power of the absolute temperature. This statement is known as Stefan Boltzmann law. Equal to Directly proportional to None of these Inversely proportional to Equal to Directly proportional to None of these Inversely proportional to 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 = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The value of Prandtl number for air is about 0.1 0.3 0.7 1.7 0.1 0.3 0.7 1.7 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The natural convection air cooled condensers are used in Water coolers Room air conditioners Domestic refrigerators All of these Water coolers Room air conditioners Domestic refrigerators All of these ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The amount of heat flow through a body by conduction is Directly proportional to the surface area of the body Directly proportional to the temperature difference on the two faces of the body All of these Dependent upon the material of the body Directly proportional to the surface area of the body Directly proportional to the temperature difference on the two faces of the body All of these Dependent upon the material of the body ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Fourier's law of heat conduction is valid for Two dimensional cases only Regular surfaces having non-uniform temperature gradients Three dimensional cases only One dimensional cases only Two dimensional cases only Regular surfaces having non-uniform temperature gradients Three dimensional cases only One dimensional cases only ANSWER DOWNLOAD EXAMIANS APP
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