CHE 330 FA22

Draining Tank Project

Overview: You will be evaluating the volumetric flow rate out of a draining tank. One tank will

drain with a short piece of tubing, the other with a long piece of tubing attached to the spout.

Is there a difference in the drainage rate? Why or why not?

Pre-lab TopHat question: Guess which container will drain faster. Is it the one with the longer

outlet tubing or the one with the shorter piece of tubing? (there is no right or wrong answer at

this point, but you must guess before doing the experiment and refer back to your initial guess

in the evaluation.)

Experiment description: There are 2 identical tanks filled

with water to the 4 or 5 L mark. The tubing inner

diameter (ID) is 3/16 inch ID. Distances between tank

markings and the outlet of the tubing are shown below.

Both tanks are filled to the 5 L mark. At the start of the

experiment, both valves are opened at the same time.

The time to drain 1.00 L of water is recorded, along with

the actual volume drained. Which tank drains faster?

Instructor gathered measurements: These

measurements were gathered by the instructional team.

Vertical distance between 3L and 5L line on tank: 6.7 cm

Vertical distance between 4L and 5L line on tank: 3.4 cm

Vertical distance from 3L line to end of short tube: 17.5 cm

Time to drain 1.00 L (sec)

Trial 1

Trial 2

Trial 3

Vertical distance from 3L line to end of long tube: 134.5 cm

Each tank was drained of 1.00L of water three times. The data for each tank is shown in the

table below.

sections

Short tube tank

39.28

38.40

39.72

Long tube tank

35.56

35.59

34.76

Analysis overview:

1. Starting from the Engineering Bernoulli equation, simplify the equation for each tank.

You may neglect friction losses for the first pass. 2. Do calculations that support your results of which tank drains more quickly. You will

likely have to make some assumptions. Clearly list all assumptions. Calculate the outlet

velocity and outlet flow rate from each tank. Do these calculations for the point where

there are 5 L in the tank and for when there are 4 L in the tank to obtain a max and min

velocities and flow rates for each tank. Average the flow rate to estimate a time to

drain the tank.

3.

Calculate the time to drain 1L of water analytically. (unsteady state mass balance)

4. Calculate the velocity of the water surface inside the tank as the tank drains from 5L to

4L. What is the ratio of velocity at the surface to velocity out of the drain? Is it

reasonable to assume the surface velocity is zero in comparison to the exit velocity?

5. Compare your calculated flowrate to your measured flowrate. Remember that your

measured flowrate is an average. Do the calculated and measured flowrates show the

same result of which drains faster?

6.

Do the flowrates calculated match theoretically calculated flow rates?

7. Using your measured flowrates, calculate the friction losses occurring in each tank.

8. Friction losses generally are a function of velocity. Do your losses show this?

9. If flow rates do not match, and friction losses in the tubing itself are minimal, where else

could losses happen to slow down flow?

Deliverables

Summary: Description of the experiment, initial expectation (pre-lab), actual results

(which tank drained faster), and summary of analysis that supports the results obtained

(why did this tank drain faster). (~1/2 page)

Calculations:

O

Diagram. Draw a diagram of the experiment including all variables. Show all

necessary known parameters in a table (diameters, heights, etc).

O Knowns and assumptions: Clearly list all knowns and all assumptions used.

O Results and Analysis summary. Show experimental data and theoretical

calculated values in a table for each tank. Make sure to include outlet velocity,

outlet flow rate, and time to drain 1L. For theoretical calculations, also include

the min, max, and average velocity and flow rate for the range studied. For

experimental include the vertical velocity of the water surface in the tank. Show

the friction losses that might account for the differences from theoretical non-

friction calculations.

o Analysis and Calculations. Show clearly labelled calculations for the information

in the results and analysis summary table. These may be handwritten. Make

sure all assumptions are clearly listed.

Conclusion. Describe clearly how the analysis supports your observations.

a. What is the ratio of velocity at the surface to velocity out of the drain? Is it

reasonable to assume the surface velocity is zero in comparison to the exit

velocity?

b. Compare your calculated flowrate to your measured flowrate. Do the calculated

and measured flowrates show the same conclusion of which tank drains faster? C. Do the calculated flowrates match theoretical flowrates? If not, what could be

the reason?

d.

Compare your estimated friction losses for each tank. Friction losses generally

are a function of velocity. Do your losses show this?

e. If friction losses in the tubing itself are minimal, where else could losses happen

to slow down flow?

Learning Community Participation. You are allowed, and encouraged, to discuss and

work with your learning community on this project. However, you are not allowed to

copy someone else's work. Please identify who you worked with on this project. This is

purely for informational purposes and will not affect your grade.

People you worked with on this project

Name

Grading Rubric

/10

Part of your learning community? (yes or

no)

Satisfactory

(70-90 %)

Summary: Description of Parts are missing. It's there but

the experiment, initial

parts may be

expectation, actual

results, and summary of

poorly written.

analysis that supports

the results obtained.

(~1/2 page)

Calculations

Clear diagram

/4

Poor (<70%)

Exemplary

(90-100%)

Clearly and well

written and no

more than 1

page

Clear drawing

with caption

describing the

drawing.

Variables are

clearly labelled. Clear list of known

parameters and data

given

/8

Assumptions clearly listed

_/8

Results summary.

Well formatted table of

calculated results from

theory and experiment

/10

Analysis and calculations.

Clear and accurate

calculations

Total

/20

Conclusion.

Clearly written

conclusion of the

analysis

/20

__/70

includes units, all

known variables

and given data

are included,

Assumptions

used are clearly

stated and are

correct

Easy to read

table, includes

units, includes

table title, all

requested data is

included.

Clear and correct

calculations

Clearly written

conclusion of

the analysis