Hot water (cph = 4188 j/kg·k) with a mass flow rate of 2.5 kg/s at 100°c enters a thin-walled concentric tube counterflow heat exchanger with a surface area of 23 m2 and an overall heat transfer coefficient of 1000 w/m2 ·k. cold water (cpc = 4178 j/kg·k) with a mass flow rate of 5 kg/s enters the heat exchanger at 20°c. determine (a) the heat transfer rate for the heat exchanger and (b) the outlet temperatures of the cold and hot fluids. after a period of operation, the overall heat transfer coefficient is reduced to 500 w/m2 ·k, so determine (c) the fouling factor that caused the reduction in the overall heat transfer coefficient