Heat and Mass Transfer In convection heat transfer from hot flue gases to water tube, even though flow may be turbulent, a laminar flow region (boundary layer of film) exists close to the tube. The heat transfer through this film takes place by Conduction Convection Both convection and conduction Radiation Conduction Convection Both convection and conduction Radiation ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Thermal diffusivity of a substance is given by (where h = Thermal diffusivity, ρ = Density of substance, S = Specific heat, and k = Thermal conductivity) h = ρS/k h = S/ρk h = k/ ρS h = kρ/S h = ρS/k h = S/ρk h = k/ ρS h = kρ/S ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The heat transfer from a hot body to a cold body is directly proportional to the surface area and difference of temperatures between the two bodies. This statement is called Stefan's law Newton's law of cooling First law of thermodynamics Newton's law of heating Stefan's law Newton's law of cooling First law of thermodynamics Newton's law of heating 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 20°C 60°C 66.7°C 40°C 20°C 60°C 66.7°C 40°C ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Kirchhoff's law states that 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 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 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Metals are good conductors of heat because Their atoms are relatively far apart They contain free electrons They have high density Their atoms collide frequently Their atoms are relatively far apart They contain free electrons They have high density Their atoms collide frequently ANSWER DOWNLOAD EXAMIANS APP
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