Lab Equipment Report

This report covers three equipment on which experiments were performed. The list contains:

Level Control Trainer

Flow Control Trainer

Double Pipe Heat Exchanger

Level Control Trainer

Objective:

To control the shift of set-point of the flow rate via continuous PI-control.

Apparatus:

The equipment being handled was GUNT Level Control Trainer.

A transparent plastic tube serves as level holding tank.

To avoid spill it is equipped with an overflow pipe leading directly back to the supply

tank.

The outlet hand valve (HV1), mentioned number 3 in the diagram, allows to change the

level tanks drain rate and to cause disturbances.

A pump inside the water reservoir conveys the water through all the circuit.

A pneumatic control valve driven by compressed air serves as the actuator in the control

circuit.

It is supplied via the pressure regulator unit which is mounted on the side of the frame

indicated as number 7. It controls the air pressure.

A tank with an inspection glass serves as the supply reservoir tank.

The water level in the cylinder is determined by a pressure transmitter which allows

further processing of the measurement value by outputting a standardized signal.

The controller displays the ongoing live results.

The equipment is connected to the computer where the data can be recorded and we can

change variables and parameters also.

Procedure:

Procedure was followed step by step as explained in the equipment manual.

Start Up:

1. Ensured at start that drain valves are closed and the water level in the tank is sufficient.

2. Ensured the positioning of air and water inlet valves.

3. Turned on the equipment from the main supply button.

4. Waited for few seconds to make the system come to equilibrium.

5. The software also detected the respective equipment and main window appeared.

Typical Settings:

1. Opened HV1 to 40

2. Completely opened HV2

3. Closed HV3

4. Completely opened HV4

5. Set controller mode to continuous automatic mode

6. Set Kp (Gain) value to 2.0

7. Set Tn (Reset Time ) to 0.3 min

8. Set Tv (Rate Time) to 0.0 min

9. Put value of w1 (set point 1) to 200 mm

10. Put value of w2 (set point 2) to 400 mm

After setting these values:

1. Switched on pump

2. Set w1 to 200mm

3. Waited until the liquid level became stable.

4. Recorded the data with the help of software and observed the graph.

5. Changed the set point to 400 mm.

6. Observed the change in level and controller repositioned to maintain the level.

7. Let the system to get stable and recorded the values.

8. Introduced another change by setting the value to 550 mm.

9. Again observed the change

10. Recorded the value

11. Introduced disturbance by decreasing the set point to 300 mm.

12. Noted the values and observed the change in level and controller action.

Shut Down:

1. Closed the water flow by turning off the pump.

2. Set the valve positions back to zero.

3. Closed the air supply to the pneumatic controller.

4. Turned off the main power supply.

5. Exit the software.

Observations & Results:

As we can see in the graph below, W, the red line was set value, we set it to a constant

value of 200 mm, to maintain this level the controller acted spontaneously and tried to

maintain the level. In about 2 minutes time the reading gets stable as blue line coincides

with red one.

The again a change was introduced by changing the level to 400mm. The controller

opened in the response and maintained the level in less than a minute time.

Next change was to a higher level of 550 mm, after initial fluctuation, the system gets

stabilized immediately, with lower value of Y.

The final change was to drop down the value to 300 mm. The controller responded

accordingly and the system gets stable in less than 2 minutes time and stayed in perfect

equilibrium for next 10 minutes until the end of experiment.

Analysis & Conclusion:

The controller spontaneously reacts to the shift of set-point.

The controller signal (y) was fluctuating in the start. This shows that the Kp value

(GAIN) could be set to a little lower value than 2.0

The X value showed that there is no remaining control deviation as the lines were

perfectly coinciding with each other.

The controllers response time is faster than that of the system so the flow can be adjusted

accordingly.

The response time was quick; it means the control strategy was good enough for this

system.

Appendix:

Flow Control Trainer

Objective:

To control a shift of set-point of the flow rate via step PI-control

Equipment:

The equipment is GUNT Flow Control Trainer.

The variable to be controlled is the flow rate in the system.

A sump tank is provided as the water reservoir which contains a submerged pump.

A variable area glass flowmeter displays the flow rate.

An electromagnetic flow meter is provided to monitor flow value.

A hand operated valve with a scale allows regulation of the water flow through the pipe

system and to cause disturbances.

An electrically operated control valve serves as the actuator in the control circuit.

A tank with an inspection glass serves as the supply tank.

The flow rate in the pipe system is determined by a magnetic-inductive flowmeter which

allows further electronic processing of the measurement value.

The equipment is connected to the computer where we can process the recorded data and

variations and settings can be introduced also.

Procedure:

Procedure was followed step by step as explained in the equipment manual.

Start Up:

1. Ensured at start that drain valves are closed and the water level in the tank is sufficient.

2. Ensured the positioning of valves.

3. Turned on the equipment from the main supply button.

4. Waited for few seconds to make the system come to equilibrium.

5. The software also detected the respective equipment and main window appeared.

Typical Settings:

1. Completely opened the hand valve, HV1

2. Set HV2 to 30 opening

3. Set controller mode to Step, Automatic mode

4. Set value of Kp (Gain) / (Xp = 1/Kp) to 5.0 / 0.2

5. Set Tn (Reset Time ) to 0.05 min

6. Set Tv (Rate Time) to 0.0 min

7. Put value of w1 (set point 1) to 600 Ltr/min

After putting these values, carried on the experiment by:

8. Switched on pump.

9. Set w1 to 600 ltr/h and waited until the value of flow rate has reached a state of stability.

10. After stability changed the value to 1000 ltr/h to get new set of data and observed the

action of controller.

11. Changed the value of flow rate to different flow rate value to observe the control action.

12. Noted the data and observed the change in flow rate and its control by the controller

action.

Shut Down:

1. Closed the water flow by turning off the pump.

2. Set the valve positions back to zero.

3. Turned off the main power supply.

4. Exit the software.

Observations & Results:

Data Table was generated with software as follows.

FLOW CONTROL TRAINER

Data Start

X W Y KP TN TV

l/h l/h l/h min min

09:30:26 600.6175 600.0000 75.8623 5.0000 0.0500

09:30:46 600.2500 600.0000 44.1164 5.0000 0.0500

09:31:06 600.8625 600.0000 54.1171 5.0000 0.0500

09:31:26 600.4950 600.0000 51.6301 5.0000 0.0500

09:31:46 600.1023 600.0000 19.4621 5.0000 0.0500

09:31:06 600.0041 600.0000 41.8835 5.0000 0.0500

09:32:26 1004.5375 1000.0000 26.3702 5.0000 0.0500

09:32:46 1004.6600 1000.0000 37.5774 5.0000 0.0500

09:33:06 1003.4350 1000.0000 49.4129 5.0000 0.0500

09:33:26 1003.8025 1000.0000 38.3236 5.0000 0.0500

09:33:46 1002.3125 1000.0000 48.1240 5.0000 0.0500

09:34:06 1001.0055 1000.0000 51.3912 5.0000 0.0500

09:34:26 1000.0023 1000.0000 16.3535 5.0000 0.0500

09:34:46 1000.0021 1000.0000 43.6480 5.0000 0.0500

Data End

Analysis & Conclusion:

The controller spontaneously reacts to the shift of set-point, but the controller signal only

rises slowly.

The reaction was faster using some bigger Kp (Kp = 1/Xp) value (GAIN). The

fluctuations are due to higher value of gain which is changing also.

The Tn value (RESET TIME) ensures that there is no remaining control deviation.

The control quality is acceptable for this system as it stabilizes the system to the values of

600 & 1000 ltr/hr in less than 2 minutes time with little variations.

0

200

400

600

800

1000

1200

9:29:31 9:30:14 9:30:58 9:31:41 9:32:24 9:33:07 9:33:50 9:34:34 9:35:17

W

Y

Double Pipe (Tubular) Heat Exchanger

Objective:

Comparison of Parallel Flow and Counter and representation of temperature curves.

Apparatus:

Apparatus is GUNT WL 110 Heat Exchanger with service unit.

1 Base plate 7 Couplings

2 Connecting block 8 Bolts

3 Right housing half 9 Regulator valve for hot water

(V1) 4 Tank cover 10 Regulator valve for cold water

(V2) 5 Left housing section

6 Control and display panel

WL 110.01 Tubular Heat Exchanger:

Fig A : WL 110.01 with base plate

Figure above shows the WL 110.01 Tubular Heat Exchanger with base plate.

The tubular heat exchanger consists of two double tubes.

In the double tubes, the transparent outer tube allows the stainless steel inner tube to be

seen.

Two separate areas are created, the tube area (inside the inner tube) and the shell

(between the inner tube and the outer tube).

Both the tube areas and the shells of the two double tubes are connected in series.

Cold and hot water flow along the inner tubes either in the same direction (parallel flow)

or in opposite directions (counter flow).

Procedure:

Start Up:

Attached the tubular heat exchanger on the service unit.

Connected the plug for the hot water temperature (TI2).

Connected the plug for the cold water temperature (TI5).

Connected the hoses for hot water into the corresponding connections on the tubular heat

exchanger.

Connected the hoses for cold water into the corresponding connections. Turned on the

PC also and started the GUNT software.

Operation:

Turned on the power supply switch.

Checked the water level in the hot water tank.

Opened the regulator valve for cold water V2 and the regulator valve for hot water V1.

Started the pump.

Set the desired hot water set point SP(T7 ) on the controller to 70 C.

Set the desired cold water flow rate using the regulator valve V2 and the desired hot

water flow rate using the regulator valve V1.

Turned on the heater.

Recorded the data values until equilibrium.

The water temperature T7 is no longer rising.

The measured values only change slightly.

The heat flow values Qh and Qc are similar.

Repeated the process for both counter and parallel flow arrangements.

Shut Down:

When the experiment is complete, first turn off the heater.

Then stopped the pump.

Closed the valves V1 and V2.

Close the cold water feed at the cold water mains.

Turned off the main power supply button.

Observations & Results:

Values were noted down once stabilized.

Values of km was noted down from measured values from the software.

was noted from measured value file or can be calculated as: = . .

Where, =

ln(

) and = 3 4, = 1 6

Experiment Run

#

Flow

Direction

,

Ltr/min

SP

(T7)

oC

T1

oC

T3

oC

T4

oC

T6

oC

km

kW/(m2K)

kW

1

1 PF 1.4 70 65 50.3 9.2 21.9 1.30 1.29

2 CF 1.4 70 68 53.1 12.7 25.1 1.28 1.25

Conclusion & Analysis:

The temperature profiles were observed during the experiment. The difference between

the efficiency of heat exchange in parallel and counter mode was observed and it was

quite clear also.

Temperature of cold stream rise more sharply in counter flow as compared to parallel

flow due to higher heat transfer rate.

Gradient of heat transfer remains constant for counter flow.

Appendix:

Counter Flow Profile:

Parallel Flow Profile:

0

10

20

30

40

50

60

70

80

Tem

pe

ratu

re

Counter Current Flow

Hot Fluid

Cold Fluid

0

10

20

30

40

50

60

70

Tem

pe

ratu

re

Parallel Flow

Hot Fluid

Cold Fluid