The oil in an engine is cooled by air in a cross-flow heat exchanger where both fluids are unmixed. Atmospheric air enters at \(10^{\circ} \mathrm{C}\) and \(0.5 \mathrm{~kg} / \mathrm{s}\). Oil at \(0.02 \mathrm{~kg} / \mathrm{s}\) enters at \(90^{\circ} \mathrm{C}\) and flows through a tube of \(10-\mathrm{mm}\) diameter. Assuming fully developed flow and constant wall heat flux, estimate the oil-side heat transfer coefficient. If the overall convection coefficient is \(60 \mathrm{~W} / \mathrm{m}^{2} \cdot \mathrm{K}\) and the total heat transfer area is \(1 \mathrm{~m}^{2}\), determine the effectiveness. What is the exit temperature of the oil?