Heat and Mass Transfer The ratio of the energy absorbed by the body to total energy falling on it is called Absorptivity Emissivity Absorptive power Emissive power Absorptivity Emissivity Absorptive power Emissive power 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/2.3 (T₁ - T₂) log (r₂/r₁) Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer If the energy radiated per second per sq. cm. of the surface for wave lengths lying between λ, and λ + dλ is represented by (eλ.dλ), then eλ is called Absorptive power None of these Emissive power Emissivity Absorptive power None of these Emissive power Emissivity ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer According to Prevost theory of heat exchange All bodies above absolute zero emit radiation Heat transfer by radiation requires no medium 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 All bodies above absolute zero emit radiation Heat transfer by radiation requires no medium 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 ANSWER DOWNLOAD EXAMIANS APP
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 Both convection and conduction Conduction Convection Radiation Both convection and conduction Conduction Convection Radiation ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Sensible heat is the heat required to Change liquid into vapour Change vapour into liquid Convert water into steam and superheat it Increase the temperature of a liquid of vapour Change liquid into vapour Change vapour into liquid Convert water into steam and superheat it Increase the temperature of a liquid of vapour ANSWER DOWNLOAD EXAMIANS APP
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