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 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 In regenerator type heat exchanger, heat transfer takes place by Direct mixing of hot and cold fluids A complete separation between hot and cold fluids Flow of hot and cold fluids alternately over a surface Generation of heat again and again Direct mixing of hot and cold fluids A complete separation between hot and cold fluids Flow of hot and cold fluids alternately over a surface Generation of heat again and again ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Thermal conductivity of water in general with rise in temperature May increase or decrease depending on temperature Remain constant Increases Decreases May increase or decrease depending on temperature Remain constant Increases Decreases ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Moisture would find its way into insulation by vapour pressure unless it is prevented by A vapour seal High vapour pressure Less thermal conductivity insulator High thickness of insulation A vapour seal High vapour pressure Less thermal conductivity insulator High thickness of insulation ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Depending on the radiating properties, a body will be black when (Where a = absorptivity, p = reflectivity, X = transmissivity.) P= 1, T = 0 and a = 0 X = 0, a + p = 0 P = 0, x = 1 and a = 0 P = 0, x = 0 and a = 1 P= 1, T = 0 and a = 0 X = 0, a + p = 0 P = 0, x = 1 and a = 0 P = 0, x = 0 and a = 1 ANSWER DOWNLOAD EXAMIANS APP
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