Heat Transfer For a given ambient air temperature with increase in the thickness of insulation of a hot cylinderical pipe, the rate of heat loss from the surface would First increase and then decrease First decrease and then increase Increase Decrease First increase and then decrease First decrease and then increase Increase Decrease ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer Nusselt number is the ratio of the Temperature difference to the temperature gradient at the wall Temperature gradient of the wall to that across the entire pipe Heat flux at the wall to that across the entire pipe None of these Temperature difference to the temperature gradient at the wall Temperature gradient of the wall to that across the entire pipe Heat flux at the wall to that across the entire pipe None of these ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer A metal ball of radius 0.1 m at a uniform temperature of 90°C is left in air at 30°C. The density and the specific heat of the metal are 3000 kg/m³ and 0.4 kJ/kg.K respectively. The heat transfer co-efficient is 50 W/m².K Neglecting the temperature gradients inside the ball, the time taken (in hours) for the ball to cool to 60°C is 555 55.5 0.15 0.55 555 55.5 0.15 0.55 ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer A composite flat wall of a furnace is made of two materials 'A' and 'B'. The thermal conductivity of 'A' is twice of that of material 'B', while the thickness of layer of 'A' is half that of B. If the temperature at the two sides of the wall are 400 and 1200°K, then the temperature drop (in °K) across the layer of material 'A' is 160 125 133 150 160 125 133 150 ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer In which mode of heat transfer, the Biot number is important? Forced convection Transient heat conduction Natural convection Radiation Forced convection Transient heat conduction Natural convection Radiation ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer In case of a multipass shell and tube heat exchanger, providing a baffle on the shell side __________ the heat transfer rate. Decreases May increase or decrease, depends on the type of baffle Does not affect Increases Decreases May increase or decrease, depends on the type of baffle Does not affect Increases ANSWER DOWNLOAD EXAMIANS APP
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