Question

Lead shot is made by dropping molten lead (ρ = 10,600 kg/m3) from a drop tower. Each pellet, a sphere 2-mm in diameter, is cooled as it passes through air at 10 ºC. Assume the shot falls at its terminal velocity. The lead must be solidified from its molten state at 327 ºC to a solid state before it reaches the pool of water at the bottom of the drop tower. The enthalpy of fusion for lead is 24.5 kJ/kg. Ignoring radiation, determine the minimum required height of the drop tower (in m).

Answer 1