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EMCH 361 Lab Report Template by hoq28342

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									  Grand Valley State University
 The Padnos School of Engineering




MODAL EMISSIONS BENCH
 EGR 450 Manufacturing Controls
         Dr. Hugh Jack




            Team:
         John Fountain
         Brent Tornga
                                            Table of Contents

Table of Contents ________________________________________________2

Executive Summary ______________________________________________3

Sample Conditioner ______________________________________________3

Emission Bench _________________________________________________4

Controls ________________________________________________________7

Conclusions ____________________________________________________8

References______________________________________________________9



      List of Figures and Tables



Figure 1 – Sample Conditioning Unit................................................................................. 3
Figure 2 – Modal Emission Bench ..................................................................................... 5
Figure 3 - OPE-325 Control Unit ....................................................................................... 5
Figure 4 - OPE-325 Control Unit ....................................................................................... 6
Figure 5 – Main Control Panel ........................................................................................... 7
Figure 6 – Main Control Panel ........................................................................................... 8
Executive Summary
    An existing emission analyzer was to be made operational by the end of the
semester. Two emissions benches were donated from General Motors Co. in the summer
of 2003. The benches have the ability to measure the concentrations of CO, NOx, CO2,
O2, HC and an incoming CO2 coming from the exhaust of an internal combustion engine.



Sample Conditioner
    The analyzer tests engine exhaust coming out of different parts of the engines
exhaust system. The conditioning unit for the analyzer performs various operations to the
gas to make it suitable for testing in the analyzer. The conditioning unit has 12 inputs for
exhaust from the engine. These inputs come from various locations along the exhaust
system. By turning on the appropriate solenoid valve, the exhaust from the
corresponding location can be run through the unit. The gas flows through the unit as
solenoids valves are opened and closed based on commands from manual toggle switches
or from the main panel on the engine bench. Figure 1 shows the sample conditioning
unit.




                             Figure 1 – Sample Conditioning Unit



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    In the conditioning unit, the exhaust from the engine first runs through a dryer that
will remove moisture, this is output to a trap so fluid is removed from the exhaust. The
liquid in the trap is flushed on command through a drain port at the back of the unit. The
exhaust can then be diverted to a pump to attain the correct pressure, or it can bypass the
pump as needed. The exhaust is then run through a second dryer and any remaining
moisture is removed. Before the exhaust is moved to the modal bench, it is run through a
series of two filters to remove any dust or ash that is present from the combustion in the
engine. The exhaust mixture is then ready for testing. The conditioning unit also has a
flow meter in line that acts as a leak check to make sure that no ambient gases
contaminate the sample. The gas flow chart for the sample conditioning unit is in the
PDF file accompanying the report.

Emission Bench
    Once the gas is ready for testing, it is connected to the mix sample input port on the
back of the engine bench. The engine bench has the ability to test for the concentration
of six different gasses. Each analyzer requires a zero gas and a span gas for calibration.
For our test purposes, we will be using the Horiba MPA-21 oxygen analyzer and the
OPE-325 control unit. In this analyzer, nitrogen is used as a reference gas that must be
continuously sent into the analyzer. The input signal from the analyzer is output as
percent oxygen in units of 0-1mA on the meter of the control unit. The unit has three
input ranges, 0-5% oxygen (range 1), 0-10% oxygen (range 2), and 0-25% oxygen (range
3). So for example, on the second range, an output of 0.9mA would correspond to a
value of 90% of the range, or 9% oxygen. Figure 2 shows a picture of the modal
emission bench.




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                              Figure 2 – Modal Emission Bench
    In this case, our zero gas was pure nitrogen ran from a pressurized tank. The span
gas used was shop air. The first step to calibration was to allow only the zero gas to be
ran through the analyzer. To do this the zero button was pushed on the front of the
bench. This enacted the correct solenoids to allow the flow of the nitrogen through the
analyzer. The analyzer was zeroed by adjusting the zero potentiometer on the oxygen
analyzer controller. The pressure for the nitrogen is controlled by valves on the front of
the unit. The pressure for the nitrogen should be 15psi for the zero gas and 10 psi for the
reference gas. Figure 3 shows the regulator controls for the nitrogen. The OPE-325
control unit is shown in Figure 4.




                                Figure 3 – Pressure regulators




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                                                              Panel Meter (0-1mA)


                         Zero                                     Span




                                                            Power


                                Figure 4 - OPE-325 Control Unit


    After the analyzer was zeroed, the span button was pushed which diverted to flow of
the pure nitrogen, and allowed the span gas to be run through the analyzer. For this
experiment, since we used shop air, we used the third range, and set the span to
approximately 0.9mA. This value corresponds to what the expected oxygen content of
the shop air would be, approximately 22.5% oxygen. The flow rate for the oxygen is
controlled by a valve above the control unit, and should be set to 10 CFH. At GM, they
would use a self made mix of nitrogen and oxygen for their span gas. This mixture
would be of approximately the same oxygen content of ambient air, but was more precise
for setting the span. It was also useful since this was a “pure air”, which was free from
things that may contaminate the analyzer.
    After the bench has been calibrated, the sample button is pushed on the control panel
to change the flow to allow the sample input to be run through the analyzer. We once
again used shop air for this test to make sure that it would match up with the span
settings. The resulting amount of oxygen was 90.4%. This is a discrepancy of only
0.4%. This error more than likely is because of some small amount of a different gas in

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the piping system for the sample gas before our sample was introduced. The sample gas
flow control is located to the left of the flow chart on the front of the unit and should be
set to no less than 10 CFH.
    It is important to note that the 0-1mA output is also available on the back of the
control unit. In addition to 0-1mA, outputs for 0-10mV, 0-100mV, and 0-5V are
available on the back of the unit. A complete manual for the oxygen analyzer was
included in appendix D. A complete gas flow chart is in the PDF file accompanying the
report.

Controls
    The controls of the emissions bench are set up in a way so that the entire bench can
be controlled from the front panel. The bench uses a Modicon 884 PLC to control the
unit. The PLC has a total of fifteen cards, ten output cards and five input cards. One of
the input cards and one of the output cards are to be connected to a cell computer that
would be able to collect data, change the range, and output to the printers on the unit.
Since this computer was not included with the unit, we manually controlled the range
selection and solenoid valves.




                                 Figure 5 – Main Control Panel


    The different analyzers are selected by pressing the appropriate button on the control
panel. The panel has buttons to run the zero gas, span gas, sample, flush the traps and


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purge the system. The panel layout is shown in figure 5. Each of the buttons also has a
lamp that is enacted when the button is pushed, the lamp indicates that it is active and is
used in the ladder logic as such. With this unit, all of the lamps for the left most bank of
buttons are not working so the ladder logic that uses these lamps as inputs will not work.
Also the valve that controls the flow of the sample is not functional so it will be
activated manually. A complete Wiring diagram is attached in appendix A.




                                Figure 6 – Main Control Panel




Conclusions
    The modal emissions bench appears to work correctly. The lights for the function
buttons on the control panel are not working. This could cause problems with the ladder
logic as these lights are used to determine what has been pushed. To get the bench into
full operating mode for testing more gasses, span gasses with known contents need to be
acquired.   If the bench will ever be used for collecting data it would be a good idea to
hook up a cell computer for data acquisition. The computer could be hooked up through
the PLC as the cell computer was, or it could be connected directly to the back of the
control units to collect real time data. A simple LabView program could be used for data
acquisition from the back of the analyzer panel.


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References

1   “Instruction Manual for Horiba Model MPA-21 Oxygen Analyzer”
2   “Instruction Manual for Horiba Analyzer Control Units Models OPE-325”
3   General Motors Corporation, Chevrolet Motor Division. Modal Emission Bench
    Manuals.




Special Thanks to:


Bob Bero – Grand Valley State University
Gregory Green – General Motors
Alfred Ferszt – General Motors
Don Dennis – Horiba U.S.A.




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