A heat exchanger is employed to cool oil from \(150^{\circ} \mathrm{C}\) to \(50^{\circ} \mathrm{C}\) by using ambient water. The rate of flow of water is \(4000 \mathrm{~kg} / \mathrm{hr}\). The ambient water enters the heat exchanger at \(20^{\circ} \mathrm{C}\) and exits at \(130^{\circ} \mathrm{C}\). The average specific heat of oil is \(2.5 \mathrm{~kJ} / \mathrm{kg}-\mathrm{K}\) and that of water is \(4.185 \mathrm{~kJ} / \mathrm{kg}-\mathrm{K}\). Determine the change in entropy due to the heat exchange process.