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 Painting the surface black Giving the surface a mirror finish Painting the surface white (with aluminium paint) Roughening the surface Painting the surface black Giving the surface a mirror finish Painting the surface white (with aluminium paint) Roughening the surface ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer The Nusselt number for fully developed (both thermally and hydrodynamically) laminar flow through a circular pipe whose surface temperature remains constant is 1.66 3.66 Dependent on NRe only 88.66 1.66 3.66 Dependent on NRe only 88.66 ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer The critical radius of insulation for a spherical shell is (where, K = thermal conductivity of insulating material h0 = heat transfer coefficient at the outer surface) h0/K h0/2K 2K/h0 K/h0 h0/K h0/2K 2K/h0 K/h0 ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m².°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be Less than the steam pipe with 5 cms insulation Greater than that for uninsulated steam pipe Equal to that of the uninsulated steam pipe Less than that of the uninsulated steam pipe Less than the steam pipe with 5 cms insulation Greater than that for uninsulated steam pipe Equal to that of the uninsulated steam pipe Less than that of the uninsulated steam pipe ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer Choose the correct equation. Nu = (Re) (Pr) (St) Nu = (Re) (Pr) (Gz) Nu = (Pr)(St) Nu = (Re)(Pr) Nu = (Re) (Pr) (St) Nu = (Re) (Pr) (Gz) Nu = (Pr)(St) Nu = (Re)(Pr) ANSWER DOWNLOAD EXAMIANS APP
Heat Transfer What is the unit of thermal conductivity ? Kcal/hr.m.°C Kcal/hr.m Kcal/hr. m² °C Kcal/hr. °C Kcal/hr.m.°C Kcal/hr.m Kcal/hr. m² °C Kcal/hr. °C ANSWER DOWNLOAD EXAMIANS APP
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