One would like to find preheat 2 tons / h of a solution with a specific heat capacity of 3.35 kJ / kg * K from 15 C to 70 C using hot water. The water temperature drops from 95 C to 35 C. Heat thru coefficient U = 700 W/m2 * K. Calculate the heat surface and consider the heat exchanger should be with the flow or countercurrent.