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 = (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) tm = loge (Δt1 - Δt2)/ Δt1/Δt2 tm = tm = (Δt1 - Δt2) loge (Δt1/Δt2) tm = loge (Δt1/Δt2)/ (Δt1 - Δt2) ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The emissivity for a black body is 0.75 1 0.5 0.75 1 0.5 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Heat is transferred by all three modes of transfer, viz. conduction, convection and radiation in Boiler Steam condenser Refrigerator condenser coils Electric heater Boiler Steam condenser Refrigerator condenser coils Electric heater ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Log mean temperature difference in case of counter flow compared to parallel flow will be Less Depends on other factors Same More Less Depends on other factors Same More ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Moisture would find its way into insulation by vapour pressure unless it is prevented by High thickness of insulation A vapour seal High vapour pressure Less thermal conductivity insulator High thickness of insulation A vapour seal High vapour pressure Less thermal conductivity insulator ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer A designer chooses the values of fluid flow rates and specific heats in such a manner that the heat capacities of the two fluids are equal. A hot fluid enters the counter flow heat exchanger at 100°C and leaves at 60°C. A cold fluid enters the heat exchanger at 40°C. The mean temperature difference between the two fluids is 20°C 66.7°C 40°C 60°C 20°C 66.7°C 40°C 60°C ANSWER DOWNLOAD EXAMIANS APP
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