Water flowing at the rate of 12.6 kg/s is to be cooled from 90 C to 65 C by means of an equal fl ow rate of cold water entering at 40 C. The water velocity will be such that the overall coefficient of...

Water flowing at the rate of 12.6 kg/s is to be cooled from 90C to 65C by means of an equal fl ow rate of cold water entering at 40C. The water velocity will be such that the overall coefficient of heat transfer U is 2300 W/m²
K. Calculate the heat exchanger surface area needed for each of the following arrange ments: (a) parallel flow, (b) counterflow (c) a multipass heat exchanger with the hot water making one pass through a well-baffled shell and the cold water making two tube passes through the tubes and (d) a cross-flow heat exchanger with both sides unmixed.