Reference no: EM132152992

Lab - Expansion Processes of a Perfect Gas

Assignment: Complete the lab tests according to the given requirement. Write one about 2000-2500 word report and submit it by the due time.

In the report, you need to do the following analysis.

Test A -

Draw the capacity ratio v.s. pressure graph. Discuss how well the results obtained from the lab compared with the expected results (you should find the exact heat capacity ratio yourself from library, internet or some other sources), by putting the test results and the expected results in the same graph. Explain the reasons for any difference.

The exact heat capacity ratio varies between 1.399 and 1.401 for temperature in the range of -40^o to 50^o. You may use 1.4 as the exact heat capacity ratio in your report.

Discuss why the initial expansion process can be considered adiabatic?

Test B -

Discuss

How well the result obtained compared to the expected result? Give possible reasons for any difference. The exact volumes of the large and the small vessels are 22.4 and 9.1 litres, respectively.

Comment on how the rate of change affects the temperature of the air inside the vessels.

The report will be assessed based on the following criteria:

Introduction and conclusion - This section outlines the aims of the laboratory tests and the main outcomes of the report. The purpose of the report needs to be clearly stated. In the conclusion section, the main outcomes of the laboratory test need to be summarized.

Description of the methodology - A student needs to present the methodology, describe the test procedure and explain the basic theory using their own words. It is not acceptable to copy from the lab note.

Results - This is the main part of the report. It will be assessed based on whether all relevant data are presented, how well the data are organized, how well charts and tables are presented, whether the methods for generating the data are correct and if a student show a good understanding of the fundamental theory. If a student makes fundamental mistakes, he/she will lose a significant percentage of marks.

Discussion - Based on the results obtained from the test, a student needs to discuss what are the outcomes of the tests.

Writing - The writing needs to be logical, clear, concise.

The equipment includes -

A common base plate (4)

Top plate (2)

Large vessel (3)

Small vessel (6)

Air pump (9)

Pressure sensors (P & V)

Sensor P measures the pressure inside the larger pressure vessel (3)

Sensor V measures the vacuum inside the smaller vacuum vessel (6) (Positive values for vacuum pressure)

Temperature sensors T1 and T2 inside each vessel Valves

V1 - the large vessel to atmosphere

V2 - the large vessel to the small vessel (via a large bore pipe)

V3 - the small vessel to atmosphere

V4 - pump to the large vessel (pressurize the large vessel)

V5 - needle valve connecting the large vessel to the small vessel

V6 - the large vessel to the small vessel (via needle valve V5)

V7 - pump to the small vessel (the pump draws air from the small vessel)

Test A - Determination of Heat Capacity ratio

Procedure -

1. Measure and record P_atm using a barometer.

2. Close ball valves V1 and V3 and open valve V4.

3. Pressurize the large vessel by switching on the air pump. When P reaches approximately 30 kN/m², switch off the air pump and close valve V4.

4. Wait until pressure P in the large vessel has stabilized (P will fall slightly as the vessel contents cools to room temperature).

5. Record the starting pressure P_s.

6. Open the close valve V1 very rapidly with a snap action to allow a small amount of air to escape from the vessel.

7. Record P_i. (accurate instantaneous value)

8. Allow the vessel contents to return to ambient temperature then record the final pressure P_f.

9. By repeating steps 6 to 8, the exercise can be repeated at different initial pressures in the vessel (P_f becoming P_s for the subsequent run).

Following table can be used to record the pressures.

Test B - Determination of ratio of volume using an isothermal process

Procedure -

Measure and record P_atm using a barometer.

Close ball valves V1 and V3 and Valve V5. Open valve V4.

Pressurise the large vessel by switching on the air pump. When P reaches approximately 30 kN/m², switch off the air pump and close valve V4.

Wait until pressure P in the large vessel has stabilised (Pressure will fall slightly as the vessel contents cools to room temperature).

Record the starting pressure P_s.

Ensure that needle valve V5 is fully closed then open isolating valve V6. Open needle valve V5 very slightly to allow air to leak from the large vessel to the small vessel. Adjust V5 to so that P falls slowly with no change in T₁ or T₂ (if the flow of air is too fast then T1 and T2 will change and the exercise must be repeated).

As the pressure P falls in the large vessel and the pressure rises in the small vessel, valve V5 can be opened slightly to reduce the duration of the exercise.

Allow the contents of both vessels to stabilise in pressure and temperature then record the final pressure P_f.

Repeat the exercise at four different initial pressures in the large vessel. The following table can be used to record the pressures.

Attachment:- thermal.zip