Heat and Mass Transfer The total radiation from a black body per second per unit area is ________ fourth power of the absolute temperature. This statement is known as Stefan Boltzmann law. Equal to Directly proportional to Inversely proportional to None of these Equal to Directly proportional to Inversely proportional to None of these ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The most commonly used method for the design of duct size is the Velocity reduction method Equal friction method Static regains method Dual or double method Velocity reduction method Equal friction method Static regains method Dual or double method 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 = 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) tm = loge (Δt1/Δt2)/ (Δt1 - Δt2) tm = loge (Δt1 - Δt2)/ Δt1/Δt2 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Unit of thermal conductivity in M.K.S. units is K calm/hr °C K cal/kg m² °C K cal/hr m² °C K cal m/hr m² °C K calm/hr °C K cal/kg m² °C K cal/hr m² °C K cal m/hr m² °C ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer 40% of incident radiant energy on the surface of a thermally transparent body is reflected back. If the transmissivity of the body be 0.15, then the emissivity of surface is 0.75 0.55 0.45 0.4 0.75 0.55 0.45 0.4 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer A cube at high temperature is immersed in a constant temperature bath. It loses heat from its top, bottom and side surfaces with heat transfer coefficients of h₁, h₂ and h₃ respectively. The average heat transfer coefficient for the cube is h₁ + h₂ + h₃ 1/h₁ + 1/h₂ + 1/h₃ None of these (h₁.h₂.h₃)1/3 h₁ + h₂ + h₃ 1/h₁ + 1/h₂ + 1/h₃ None of these (h₁.h₂.h₃)1/3 ANSWER DOWNLOAD EXAMIANS APP
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