practical 2

 CP5065 Introduction to Chemical Product Design

Practical 2 – Air Lift Pump Challenge

Due to the resurgence of COVID-19 in Singapore, the originally planned air-lift pump challenge has to be changed. This practical has to be carried out at the home of one of the team members.

For this hands-on activity, the roles and responsibilities of each member must be designed and listed down. Discuss and appoint members to the following roles:

1. Team leader: Ensure all the procedures are executed

2. Experimenter: Set up and carry out the hands-on part of the experiment

3. Timekeeper: Record the time, tabulate data and plot graphs

4. Blogger: Consolidate and type the documentation in the blog (1 to 2 members)

All members are to jointly work on the discussion

1. Experimental Setup

The experimenter will set up the apparatus as per Figure 1 below.

Figure 1: Experimental Setup

For the small segment of hose, you can make one yourself (see photo instructions below)

 

2. Experiment Details

Experiment 1

Referring to the Figure 2 below, find a way to fix the U-shape tube to be 10cm from the base of the jug (i.e. b = 10cm). You can also ask your family members to hold the tube for you. Prepare an accurate way to measure the volume of water for the determination of the flowrate.

Adjust the length of the tubing inside the U-shape tube. Such that a is 2cm.  Slide the hose segment (refer to Figure 1) up or down so that the PVC tube does not dislodge from the U-shape tube and does not have any kink.

Turn on the air pump and determine the pump flowrate rate. Repeat the test 3 times and average the timing

Repeat the experiment with different values of a from 2 to 10 cm. Tabulate your findings using the worksheet enclosed

Figure 2 Positioning of the tube

Experiment 2

Referring to Figure 2 again, with a fixed at 2 cm, adjust b to 12 cm. Measure the pump flowrate. Repeat the experiment with different values of b from 12 to 20 cm. Tabulate your findings using the worksheet enclosed.

For the experiment, have someone to video record a segment of the experiment. The video should capture the laptop screen with members with camera switched on MS Teams. The picture below explains the requirement better.

3. Experiment Worksheet

Experiment 1

b = 10cm

a (cm)	X (cm)	Flowrate (ml/s)			Average Flowrate (ml/s)
		Run 1	Run 2	Run 3
2	6.4	2.60	3.26	3.96	3.27
4	11.0	8.01	3.70	6.97	6.23
6	9.0	7.45	5.00	4.57	5.67
8	7.0	2.78	3.06	3.67	3.17
10	5.0	1.32	1.37	1.41	1.37

Flowrate is volume of water collected/transferred divided by time taken

Experiment 2

a = 2cm

b (cm)	Y (cm)	Flowrate (ml/s)			Average Flowrate (ml/s)
		Run 1	Run 2	Run 3
10*	13.0	10.1	11.60	11.71	11.14
12	11.0	5.84	6.92	6.58	6.45
14	9.0	2.47	2.29	2.53	2.43
16	7.0	0.0	0.0	0.0	0.0
18	5.0	0.0	0.0	0.0	0.0
20	3.0	0.0	0.0	0.0	0.0

Flowrate is volume of water collected/transferred divided by time taken

*This is the same setting as the first run in experiment1. You do not need to repeat it. Just record the results will do.

4. Questions & Tasks

1. Plot tube length X versus pump flowrate. (X is the distance from the surface of the water to the tip of the air outlet tube). Draw at least one conclusion from the graph.

The greater the distance from the surface of the water to the tip of the air outlet tube ,the higher the pump flowrate.

2. Plot tube length Y versus pump flowrate. (Y is the distance from the surface of the water to the tip of the U-shape tube that is submerged in water). Draw at least one conclusion from the graph. The greater the distance between the tip of the U-tube and water surface, the greater the pump flowrate.

3. Summarise the learning, observations and reflection in about 150 to 200 words.

4. Explain how you measure the volume of water accurately for the determination of the flowrate?

Mark a specific volume (e.g. 100ml), and measure the time taken for the water lvl to hit the specific volume and divide the volume by time taken to find flowrate.

5. How is the liquid flowrate of an air-lift pump related to the air flowrate? Explain your reasoning.

When the air flowrate is high,the pressure produced will be high and liquid flowrate will increase.

6. Do you think pump cavitation can happen in an air-lift pump? Explain.

Yes ,when flowrate is small,it will cause NPSHR=NPSHA,therefore pump cavitation will happened.However,when flowrate is high,NPSHA will higher than NPSHR,the pump cavitation will be avoided.

7. What is the flow regime that is most suitable for lifting water in an air-lift pump? Explain.

Flow regime in experiment 1. which fixed b=10cm.This is because the pressure outside is change a little bit   ,and the flowrate affected but it has the minimum flowrate and will no occur the situation like experiment 2 which does not have any flowrate when b is very big.

8. What is one assumption about the water level that has to be made? Explain.

5. Submission

The worksheet, graphs, answers to questions, discussion and reflection should all be captured in the Blog together with photo(s) and video(s) by 28 May 2021, 11:59pm. MS Excel should be used for plotting the graphs.