Heat and Mass Transfer The concept of overall coefficient of heat transfer is used in heat transfer problems of Conduction and convection Conduction Convection Radiation Conduction and convection Conduction Convection Radiation 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 Their atoms collide frequently They have high density Their atoms are relatively far apart They contain free electrons Their atoms collide frequently They have high density ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Reynolds number (RN) is given by (where h = Film coefficient, l = Linear dimension, V = Velocity of fluid, k = Thermal conductivity, t = Temperature, ρ = Density of fluid, cp = Specific heat at constant pressure, and μ = Coefficient of absolute viscosity) RN = hl/k RN = V²/t.cp RN = ρ V l /μ RN = μ cp/k RN = hl/k RN = V²/t.cp RN = ρ V l /μ RN = μ cp/k 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 unit of Stefan Boltzmann constant is watt/cm4 °K watt2/cm °K⁴ watt/cm2 °K⁴ watt/cm3 °K watt/cm4 °K watt2/cm °K⁴ watt/cm2 °K⁴ watt/cm3 °K ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Sensible heat is the heat required to 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 Change liquid into vapour Change vapour into liquid ANSWER DOWNLOAD EXAMIANS APP
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