Solutions%20to%20Homework#7

# Solutions%20to%20Homework#7 - Assignment Solution 7...

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Assignment Solution 7 Chemical Engineering 2800 (Summer 2008) Fundamentals of Process Engineering University of Utah Dr.Mataz Alcoutlabi Problem 1 18.21, p. 555 Hot air that is used to dry pharmaceuticals is recycled in a closed loop to prevent the contamination of the moist material from atmospheric impurities. In the first conditioning step for the air, 5000 kg mol/hr at 105 kPa and 42C with a 90% relative humidity are fed to a condenser to remove some of the water picked up previously in the process. The air exits the condenser at 17C and 100 kPa containing 91 kg mol/hr of water vapor. Next, the air is heated in a heat exchanger at 90C, and then goes to the dryer. By the time the air enters the dryer, the pressure of the stream has dropped to 95 kPa and the temperature is 82C. a) How many kgmol/h water enter condenser? Data: C T B A p + - = * ln T (=) K, p* (=) mmHg A = 18.3036 B = 3816.44 C = -46.13 Given * 9 . 0 9 . 0 * p p or p p w w = = tot w w p p y = tot tot tot tot w tot w w n p p n p p n y n * 9 . 0 = = = + - = C T B A n p n tot tot w exp 9 . 0 ( 29 ( 29 - + - = 760 325 . 101 13 . 46 14 . 315 44 . 3816 3036 . 18 exp 5000 105 9 . 0 w n h kgmol n w / 74 . 350 = Condenser Heat Exchanger 90 ° C Drier 1 2 3 4 5 RH = 90% H 2 O condensate Air at 100 kPa 17 ° C 91 kg mol/hr H O 95 kPa 82 ° C Air 5000 kg mol/hr at 105 kPa

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b) What is the flow rate of condenser? Balance on H2O over condenser 0 3 2 1 = - - w w w n n n h kgmol n w / 74 . 259 91 74 . 350 2 = - = c) What is the dew point of the air in the stream entering the condenser? 3
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## This note was uploaded on 09/07/2009 for the course CHEN 2800 taught by Professor Process during the Summer '08 term at University of Utah.

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Solutions%20to%20Homework#7 - Assignment Solution 7...

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