To ask an engineering question please visit our forum site at Eng-Tips.

A counterflow double-pipe heat exchanger is currenily used to heat 2.5 kg/s of water from 25°C to 65°C by cooling an oil [cp = 2.2 kj/(kg K)| from 150°C to 95°C. It is desired to 'bleed off' 0.6 kg/s of water at 45°C so that the single exchanger will be replaced by a two-exchanger arrangement which will permit this. The overall heat transfer coefficient is 400 W/(m2 K) for the single exchanger and may be taken as this same value for each of the two smaller exchangers. The same oil flow is used for the two-exchanger arrangement, except that the flow is split between the two exchangers. Determine the areas of each of the smaller exchangers and the oil flow through each. Assume that the water flows in series through the two exchangers with the bleed-off taking place between them. Assume that the two smaller exchangers have the same areas. Take cp,water 4180 J/(kg K).

please help me in solving this..i have tried my best and i have wasted 4 hours on it..plese any expert help me