Heat and Mass Transfer The heat transfer by conduction through a thick sphere is given by Q = 2πkr1 r2 (T1 - T2)/ (r2 - r1) Q = 8πkr1 r2 (T1 - T2)/ (r2 - r1) Q = 6πkr1 r2 (T1 - T2)/ (r2 - r1) Q = 4πkr1 r2 (T1 - T2)/ (r2 - r1) Q = 2πkr1 r2 (T1 - T2)/ (r2 - r1) Q = 8πkr1 r2 (T1 - T2)/ (r2 - r1) Q = 6πkr1 r2 (T1 - T2)/ (r2 - r1) Q = 4πkr1 r2 (T1 - T2)/ (r2 - r1) ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer According to Newton's law of cooling, the heat transfer from a hot body to a cold body is Either (A) or (B) Directly proportional to the difference of temperatures between the two bodies Both (A) and (B) Directly proportional to the surface area Either (A) or (B) Directly proportional to the difference of temperatures between the two bodies Both (A) and (B) Directly proportional to the surface area ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The logarithmic mean temperature difference (tm) is given by (where Δt1 and Δt2 are temperature differences between the hot and cold fluids at entrance and exit) tm = loge (Δt1/Δt2)/ (Δt1 - Δt2) tm = loge (Δt1 - Δt2)/ Δt1/Δt2 tm = tm = (Δt1 - Δt2) loge (Δt1/Δt2) tm = (Δt1 - Δt2)/ loge (Δt1/Δt2) tm = loge (Δt1/Δt2)/ (Δt1 - Δt2) tm = loge (Δt1 - Δt2)/ Δt1/Δt2 tm = tm = (Δt1 - Δt2) loge (Δt1/Δt2) tm = (Δt1 - Δt2)/ loge (Δt1/Δt2) ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The ratio of the energy absorbed by the body to total energy falling on it is called Absorptivity Emissivity Emissive power Absorptive power Absorptivity Emissivity Emissive power Absorptive power 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 = 0, ρ = 1 and τ = 0 α + ρ = 1 and τ = 0 α = 1, ρ = 0 and τ = 0 α = 0, ρ = 0 and τ = 1 α = 0, ρ = 1 and τ = 0 α + ρ = 1 and τ = 0 α = 1, ρ = 0 and τ = 0 α = 0, ρ = 0 and τ = 1 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The heat is transferred by conduction, convection and radiation in None of these Boiler furnaces Melting of ice Condensation of steam in condenser None of these Boiler furnaces Melting of ice Condensation of steam in condenser ANSWER DOWNLOAD EXAMIANS APP
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