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 = tm = (Δt1 - Δt2) loge (Δt1/Δt2) tm = loge (Δt1/Δt2)/ (Δt1 - Δt2) tm = (Δt1 - Δt2)/ loge (Δt1/Δt2) tm = loge (Δt1 - Δt2)/ Δt1/Δt2 tm = tm = (Δt1 - Δt2) loge (Δt1/Δt2) tm = loge (Δt1/Δt2)/ (Δt1 - Δt2) tm = (Δt1 - Δt2)/ loge (Δt1/Δt2) ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer According to Kirchoff's law, the ratio of emissive power to absorptivity for all bodies is equal to the emissive power of a Red hot body Brilliant white polished body Black body Grey body Red hot body Brilliant white polished body Black body Grey body 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=1, T = 0 and a = 0 P = 0, x = 0 and a = 1 X = 0, a + p = 1 P = 0, x = 1 and a = 0 P=1, T = 0 and a = 0 P = 0, x = 0 and a = 1 X = 0, a + p = 1 P = 0, x = 1 and a = 0 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer According to Stefan Boltzmann law, the total radiation from a black body per second per unit area is directly proportional to the Square of the absolute temperature Absolute temperature Cube of the absolute temperature Fourth power of the absolute temperature Square of the absolute temperature Absolute temperature Cube of the absolute temperature Fourth power of the absolute temperature 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 = = 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)] ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Upto the critical radius of insulation, Added insulation will decrease heat loss Added insulation will increase heat loss Heat flux will decrease Convective heat loss will be less than conductive heat loss Added insulation will decrease heat loss Added insulation will increase heat loss Heat flux will decrease Convective heat loss will be less than conductive heat loss ANSWER DOWNLOAD EXAMIANS APP
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