Chemical Engineering Laboratory -

Transient and Steady State Behavior of Tanks in Series 

Introduction -

This is a fluid dynamics experiment involving the filling and emptying of tanks. The objectives of the experiment include:

1. Determination of the discharge coefficient of the orifice and the equivalent length of a pipe mounted at the outlet of the two tanks. 

2. Verification of the steady-state and transient (filling AND emptying) material balances for one tank.

3. Verification of the steady-state and transient (filling AND emptying) material balances for two tanks in series.

4. The effect of error in the inlet flow rates on the predicted liquid levels.

Experimental Procedure - This experiment consists of several distinct parts, and the procedure for each part is described below. 

1. Turn on PC, screen, Opto 22 system, and power to instrument panel.

2. Bring as USB drive.

3. Execute the Labview software program on the PC.

4. Answer the questions on screen.

Enter appropriate comments into the data file so that the collected data can be readily identified.

Run 1:  Discharge Coefficients for Orifice Outlet (Tank 1) and Equivalent Pipe Lengths for Outlet Pipe (Tank 2) 

Place a stopper in the outlet of each tank. Turn on the pump and fill the upper tank until the level indicator for Tank 1 indicates that the level ≅ 85%. Turn off the pump and close all valves (except Valves 1 and 2). Do the following:

1. Enter description for Run A and set the data to record every 2 seconds.

2. Start data acquisition for Run 1.

3. After several points (approximately 10 s) of constant level have been recorded on the screen, pull the stopper from the bottom of Tank 1 (the upper tank) and allow the liquid to drain into Tank 2.

4. When Tank 1 has completely drained, pull the stopper from Tank 2.

5. Stop data acquisition when the liquid level in Tank 2 is less than 5 %.

6. Repeat this procedure one more time to give a total of two runs for each tank. 

Run 2:  Transient and Steady-State Behavior of Tank 2 alone 

At the beginning of this run, Tanks 1 and 2 should be empty, the pump should be off, all valves should be closed, and the outlets should not contain stoppers. Do the following:

1. Enter description for this run and set the data to record every 20 seconds.

2. Set the flow controller for Tank 2 to automatic mode and adjust the set point as per the T.A.'s instructions.

3. Open valve 7. Make sure valve 8 is closed (i.e. no flow into Tank 1).

4. Start the data acquisition and turn on the pump simultaneously.

5. Continue data acquisition for about 5 minutes after steady state has been achieved (AND VERIFIED) in Tank 2, unless the level in either tank is above 80% (in this case, turn off the pump).

6. VERY IMPORTANT:  TO VERIFY STEADY STATE HAS BEEN REACHED MEASURE THE LIQUID FLOW RATE OUT OF TANK 2.  IF IT IS WITHIN ±5% OF THE CALCULATED FLOW RATE (from the calibration equation) THEN STEADY STATE IS VERIFIED. ALSO, MEASURE THE STEADY STATE LIQUID HEIGHT IN TANK  2 AT STEADY STATE.  This is done to check the calibration equations.

7. Turn off the pump and allow the liquid to drain from Tank 2.

8. Turn off data acquisition when the liquid level in Tank 2 is less than 2 %.

Run 3:  Transient Behavior of Tanks 1 and 2 in Series

At the beginning of this run, Tanks 1 and 2 should be empty, the pump should be off, all valves should be closed, and the outlets should not contain stoppers. Do the following:

1. Enter description for this run and set the data to record every 2 seconds.

2. Set the flow controllers to automatic mode and adjust the set point as per the T.A.'s instructions (T.A. note: flow rates should be set high so this run should not take long).

3. Open valves 7 and 8 to allow flow into both tanks.

4. Start the data acquisition and turn on the pump simultaneously.

5. When the liquid level reaches 80 % in either tank turn the pump off.  DO NOT OVERFLOW THE TANKS.

6. Turn off data acquisition when levels in both tanks are less than 2 %

Run 4:  Transient and Steady-State Behavior of Tanks 1 and 2 in Series

At the beginning of this run, Tanks 1 and 2 should be empty, the pump should be off, all valves should be closed, and the outlets should not contain stoppers. Do the following:

1. Enter description for this run and set the data to record every 20 seconds.

2. Set the flow controllers to automatic mode and adjust the set point as per the T.A.'s  instructions.

3. Open valves 7 and 8 to allow flow into both tanks.

4. Start the data acquisition and turn on the pump simultaneously.

5. Continue data acquisition for about 5 minutes after steady state has been verified, unless the level in either tank is above 80% (in this case, turn off the pump).

6. VERY IMPORTANT: TO VERIFY STEADY STATE HAS BEEN REACHED MEASURE THE LIQUID FLOW RATE OUT OF TANK 2. IF IT IS WITHIN ±5% OF THE CALCULATED FLOW RATE (from the calibration equations, Q1 + Q2) THEN STEADY STATE IS VERIFIED. ALSO, MEASURE THE STEADY STATE LIQUID HEIGHT IN BOTH TANKS AT STEADY STATE. This is done to check the calibration equations.

7. Turn off the pump and allow the liquid to drain from both tanks.

8. Turn off data acquisition when levels in both tanks are less than 2 %.

Run 5: Check discharge coefficient for orifice outlet and equivalent pipe length for outlet Pipe

Repeat Run 1 one more time, if time permits.

Shut-Down Procedure

1. Terminate all data acquisition.

2. Remove the diskette from drive A after the data has been copied to the disk.

3. Turn off the power to PC, screen, Opto 22 system, pump, and panel.

4. Close all valves.

5. CLEAN UP ANY MESS YOU MAY HAVE CREATED.

Report Requirements -

The report should include (as a minimum) the following:

1. The values of CQ and L_eff for the tank outlets. Show the figures used to get these values. Cut the data below liquid levels of 10% when finding CQ and L_eff as the data tends to be nonlinear after this point. You should state CQ and L_eff for each run and find the average value. If you do Run 5, you should also discuss the effect of temperature change on CQ and L_eff.

2. Comparison of the measured liquid level, h₂, as a function of time from Run 2 with predictions of liquid level as a function of time using the experimental values of L_eff determined from the data of Runs 1 and 5. This should include a discussion about both the transient (filling and emptying) and steady state parts of the experiment. You must show the height vs. time figure in the report. The predicted values should have error bounds based on error in the flow rate.

3. Comparison of the measured liquid levels, h, as functions of time from Run 3 with predictions of liquid levels as functions of time using the experimental values of CQ and L_eff determined from the data of Runs 1 and 5. This should include a discussion about both the filling and emptying parts of the experiment. You must show the height vs. time figures for each tank in the report. Note that Tank 1 is independent of the level in Tank 2, but the level in Tank 2 is dependent upon the level in Tank 1.  The predicted values should have error bounds based on error in the flow rates.

4. Comparison of the measured liquid levels, h, as functions of time from Run 4 with predictions of liquid levels as functions of time using the experimental values of CQ and L_eff determined from the data of Runs 1 and 5. This should include a discussion about both the transient (filling and emptying) and steady state parts of the experiment. You must show the height vs. time figures for each tank in the report. Note that Tank 1 is independent of the level in Tank 2, but the level in Tank 2 is dependent upon the level in Tank 1. The predicted values should have error bounds based on error in the flow rates.

Attachment:- Assignment.rar