Heat and Mass Transfer According to Prevost theory of heat exchange Heat transfer by radiation requires no medium Heat transfer in most of the cases takes place by combination of conduction, convection and radiation All bodies above absolute zero emit radiation It is impossible to transfer heat from low temperature source to t high temperature source Heat transfer by radiation requires no medium Heat transfer in most of the cases takes place by combination of conduction, convection and radiation All bodies above absolute zero emit 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 Radiation Both convection and conduction Convection Conduction Radiation Both convection and conduction Convection Conduction 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/2.3 (T₁ - T₂) log (r₂/r₁) Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Depending on the radiating properties, a body will be white when(Where a = absorptivity, p = reflectivity, x = transmissivity) P = 0, x = 0 and a = 1 P=1, T = 0 and a = 0 P = 0, x = 1 and a = 0 X = 0, a + p = 1 P = 0, x = 0 and a = 1 P=1, T = 0 and a = 0 P = 0, x = 1 and a = 0 X = 0, a + p = 1 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Depending on the radiating properties, body will be transparent when (Where a = absorptivity, p = reflectivity, x = transmissivity) X = 0, a + p = 1 P = 0, x = 0 and a = 1 P = 0, x= 1, and a = 0 P=1, x = 0, and a = 0 X = 0, a + p = 1 P = 0, x = 0 and a = 1 P = 0, x= 1, and a = 0 P=1, x = 0, and a = 0 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Which of the following is a case of steady state heat transfer? Air preheaters I.C. engine Heating of building in winter None of these Air preheaters I.C. engine Heating of building in winter None of these ANSWER DOWNLOAD EXAMIANS APP
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