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 = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) 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 When α is absorptivity, ρ is reflectivity and τ is transmissivity, then for a diathermanous body, α + ρ = 1 and τ = 0 α = 0, ρ = 1 and τ = 0 α = 0, ρ = 0 and τ = 1 α = 1, ρ = 0 and τ = 0 α + ρ = 1 and τ = 0 α = 0, ρ = 1 and τ = 0 α = 0, ρ = 0 and τ = 1 α = 1, ρ = 0 and τ = 0 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Thermal conductivity of solid metals with rise in temperature normally Increases Remain constant Decreases May increase or decrease depending on temperature Increases Remain constant Decreases May increase or decrease depending on temperature ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The use of heat exchangers is made in Radiators in automobile Condensers and boilers in steam plants Condensers and evaporators in refrigeration and air conditioning units All of these Radiators in automobile Condensers and boilers in steam plants Condensers and evaporators in refrigeration and air conditioning units All of these ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer A non-dimensional number generally associated with natural convection heat transfer is Grashoff number Weber number Nusselt number Prandtl number Grashoff number Weber number Nusselt number Prandtl number ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The ratio of the thickness of thermal boundary layer to the thickness of hydrodynamic boundary layer is equal to (Prandtl number) n, where n is equal to =-1/3 1 -1 =-2/3 =-1/3 1 -1 =-2/3 ANSWER DOWNLOAD EXAMIANS APP
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