Oil is cooled by spraying a mist of the hot liquid through cool air at \(T_{\infty}=27^{\circ} \mathrm{C}\). Two droplets, each of diameter \(D=100 \mu \mathrm{m}\) and temperature \(250^{\circ} \mathrm{C}\), suddenly collide and coalesce into a single droplet. Determine the heat transfer rate from the oil to the air before and after coalescence of the droplets. The velocity of the droplets is \(V=5 \mathrm{~m} / \mathrm{s}\).