Effectiveness, ntu for heat exchangers. problem 4.9-4, p351. outlet temperature and effectiveness of an exchanger. hot oil at a flow rate of 3.00 kg/s (cp = 1.92 kj/kg×k) enters an existing counterflow exchanger at 400 k and is cooled by water entering at 325 k (under pressure) and flowing at a rate of 0.70 kg/s. the overall u = 350 w/m2 ×k and a = 12.9 m2. calculate the heat transfer rate and the exit oil temperature.