Chemical and
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Material Engineering Department| TKN page | CHE322 Home | Syllabus | 1. Friction | 2. Pumps | 3. Hilsch Tube | 4. Fluid flow | 5. Viscosity | 6. Bomb Calorimetry |
The Diamond Bar plant has a nitrogen stream at 3.0 atm and 300.oK which is presently vented to the atmosphere. The management would like to use this stream to satisfy some of the heating or cooling requirements of other processes. Their engineer, James Hank, a Cal Poly graduate, has devised a process that will produce equal amounts of a hot stream at 500oK and a cold stream at 200oK and thus satisfy simultaneously some heating and cooling requirements. Furthermore, James claims that his device will be self-sustaining because no additional heat or work need be supplied to the device. The management would like an explanation of this device.
The principles behind James' device are believed to be the same as the
Hilsch Tube, which is available in our laboratory.
Operate the Hilsch tube over the widest possible range of the operating variables.
You will be measuring temperatures and flow rates. Use thermocouples for the temperature measurement. Ask Jim Rounds for the device to measure flow rates. Study the devices available so that you will know how to obtain good data.
The laboratory work is relatively easy to complete. So be certain that
you have sufficient and good data. You should make at least six, good experimental
runs at different conditions. Note the time required to reach steady state
operation. Compute the standard error in your experimental readings and
in your calculated results.
This is mostly a "think" experiment that tests your knowledge of thermodynamics. When you perform a thermodynamic analysis of a process remember:
- both the first and second laws must be followed for the process to
be theoretically possible.
- always do the first law analysis before the second law analysis.
- if you are analyzing a process and the first law is violated you must
stop at that point. So go over the first law calculations and, if possible,
uncover the error. Examine carefully any assumption that you made. Only
after the first law analysis is correct can you perform the second law analysis.
- thermodynamic efficiency, a useful concept, compares the actual performance
with the maximum theoretical performance (usually under adiabatic and reversible
conditions, where the entropy change is zero). Note that this concept can
be applied to heat pumps, heat engines, compressors and expanders.
Analyze James' device by both the first and second laws of thermodynamics. If your analysis fails, consider that there may be a typographic error. If you find one, please correct it and continue the analysis. Use the results of this analysis to support your explanation of James' device.
Analyze the Hilsch tube data to determine the thermodynamic efficiency
or some measure of the thermodynamic efficiency. You may find that this
analysis is easier to do after you have completed the design work for James'
process as shown under Design work. Note that Kyle has some information
on the Hilsch tube.
Can you design a theoretical (i.e. 100. % efficient) process that will satisfy the requirements of James' device? You have several process units that you can employ in your design. A process unit that you should not consider (it will not work) is the Joule- expansion.
Calculate all heat and work interactions for each device used in your process and indicate how the devices should be arranged so that no additional heat or work need be supplied by the environment. Calculate what happens to the process conditions if the efficiency is only 50.%. Consider the 50.% efficiency case to be your actual design
Present the results of your experimental work. Aim to provide the reader with significant information without excessive detail. Also present the efficiency data for the Hilsch tube .
Your explanation of James' device is your design work for this process. Present your design in a flow chart showing process units, process flow lines, process conditions and heat and work terms. The temperatures of the process streams for the 100.% and 50.% efficiency cases should be presented in a table.
You should have a lively discussion after the presentation of your results.
And in this report you will be able to draw several conclusions.