# HW3 - for an extended period of time The heat exchanger...

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ME 426 Homework #3 14.10.2008 1. Following the lecture note on the u -NTU method, show that, for the case of C c < C h , )] 1 ( exp[ 1 )] 1 ( exp[ 1 * * * C NTU C C NTU - - - - - - = ε 2. A shell-and-tube exchanger (two shells, four tube passes) is used to heat 10,000 kg/h of pressurized water from 35 to 120ºC with 5,000 kg/h pressurized water entering the exchanger at 300ºC. If the overall heat transfer coefficient is 1500 W/m 2 ºC, determine the required heat exchanger area using both LMTD and u -NTU methods. 3. A counterflow, concentric tube heat exchanger used for engine cooling has been in service
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Unformatted text preview: for an extended period of time. The heat exchanger surface area of the exchanger is 5 m 2 , and the design value of the overall convection coefficient is 38 W/m 2 ºC. During a test run, engine oil flowing at 0.1 kg/s is cooled from 110ºC to 66ºC by water supplied at a temperature of 25ºC and a flow rate of 0.2 kg/s. Determine whether fouling has occurred during the service period. If so, calculate the fouling factor, R ” f (m 2 K/W)....
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