Heat Transfer The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by Roughening the surface Giving the surface a mirror finish Painting the surface white (with aluminium paint) Painting the surface black Roughening the surface Giving the surface a mirror finish Painting the surface white (with aluminium paint) Painting the surface black ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer Radiator of an automobile engine is a __________ type of heat exchanger. Cross-current Counter-current Direct contact Co-current Cross-current Counter-current Direct contact Co-current ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer While the total emissivity of a perfect black body is unity, the same for a real body is 1 between 0 and 1 0 >1 1 between 0 and 1 0 >1 ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer For gases, the thermal conductivity increases with temperature rise. For liquids, with increase in concentration, its thermal conductivity generally Remains unchanged Increases Decreases Increases exponentially Remains unchanged Increases Decreases Increases exponentially ANSWER DOWNLOAD EXAMIANS APP
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 Increase Decrease First decrease and then increase First increase and then decrease Increase Decrease First decrease and then increase First increase and then decrease ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer The thermal efficiency of a reversible heat engine operating between two given thermal reservoirs is 0.4. The device is used either as a refrigerator or as a heat pump between the same reservoirs. Then the coefficient of performance as a refrigerator (COP)R and the co-efficient of performance as a heat pump (COP)HP are (COP)R = (COP)HP = 2.5 (COP)R = 1.5; (COP)HP = 2.5 (COP)R = 2.5; (COP)HP = 1.5 (COP)R = (COP)HP = 0.6 (COP)R = (COP)HP = 2.5 (COP)R = 1.5; (COP)HP = 2.5 (COP)R = 2.5; (COP)HP = 1.5 (COP)R = (COP)HP = 0.6 ANSWER DOWNLOAD EXAMIANS APP
EXAMIANS