4.13. Our highly efficient plant has a nitrogen stream at 2.53 bar and 305.5 K which...

  

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4.13. Our highly efficient plant has a nitrogen stream at 2.53 bar and 305.5 K which is presently vented to the atmosphere. Management would like to use this stream to satisfy some of the heating or cooling requirements of other processes. Our old friend, Rocky Jones, has devised a black box that will produce equal amounts of a hot stream at 500 K and a cold stream at 111 K and thus satisfy simultaneously some heating and cooling requirements (see Figure P4.13). Furthermore, Rocky claims that his device will be self-sustaining because no additional heat or work need to be supplied to the device. Nitrogen 324 molc/hr 2.53 bar 305.5 K 162 mole/hr 1.01 bar 500 K BLACK BOXI 162 mole /hr 1.01 bar Figure P4.13 One of our new engineers, Barry Goldfinder, claims that he has a black-box device that will produce equal amounts of hot stream of 533 K and a cold stream of 77.7 K. His devicE will also be self-sustaining. (a) Are either (or both) of these devices possible? Explain. (b) Describe a process that will satisfy the requirements of Rocky's black box. Calculate all heat and work interactions for each device used in this process and indicate now the devices should be arranged so that no additional heat or work need be supplied by the environment. Assume that the heat capacity of nitrogen is 29.3 J/mol K, independent of temperature o pressure. 4.13. Our highly efficient plant has a nitrogen stream at 2.53 bar and 305.5 K which is presently vented to the atmosphere. Management would like to use this stream to satisfy some of the heating or cooling requirements of other processes. Our old friend, Rocky Jones, has devised a black box that will produce equal amounts of a hot stream at 500 K and a cold stream at 111 K and thus satisfy simultaneously some heating and cooling requirements (see Figure P4.13). Furthermore, Rocky claims that his device will be self-sustaining because no additional heat or work need to be supplied to the device. Nitrogen 324 molc/hr 2.53 bar 305.5 K 162 mole/hr 1.01 bar 500 K BLACK BOXI 162 mole /hr 1.01 bar Figure P4.13 One of our new engineers, Barry Goldfinder, claims that he has a black-box device that will produce equal amounts of hot stream of 533 K and a cold stream of 77.7 K. His devicE will also be self-sustaining. (a) Are either (or both) of these devices possible? Explain. (b) Describe a process that will satisfy the requirements of Rocky's black box. Calculate all heat and work interactions for each device used in this process and indicate now the devices should be arranged so that no additional heat or work need be supplied by the environment. Assume that the heat capacity of nitrogen is 29.3 J/mol K, independent of temperature o pressure.

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The second black box is not possible b In ... View the full answer