Water is used in both the hot and cold stream of a counter flow, concentric tube heat exchanger. The hot stream flows th

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Water Is Used In Both The Hot And Cold Stream Of A Counter Flow Concentric Tube Heat Exchanger The Hot Stream Flows Th 1 (103.62 KiB) Viewed 32 times

Water is used in both the hot and cold stream of a counter flow, concentric tube heat exchanger. The hot stream flows through the inside tube, of diameter 22mm, and has an inlet and outlet temperature of 80°C and 70°C, respectively, flowing at a rate of 24 litres per minute. The cold stream enters the outer tube of the exchanger at a temperature of 20°C at a rate of 12 litres per minute. The overall heat transfer coefficient of the heat exchanger is 1200 W m-2K-1. a) Sketch on a single set of axes a graph of the temperature against distance along the heat exchanger for both the hot and cold stream. [5 marks] b) Determine the amount of heat being exchanged between the hot and cold stream and the exit temperature of the cold stream. [6 marks] c) Determine the log mean temperature difference for this heat exchanger. [5 marks) d) When can the conductive resistance of the hot-cold interface in a heat exchange be neglected? [4 marks] e) Determine the length (in metres) of the heat exchanger, stating any appropriate assumptions. [5 marks] [Total 25 marks]