Experiment title: Heat Engine Experiment
Academic in charge of experiment:
Experiment duration: The standard scheduled time for this experiment is 90 minutes for 3 groups (A, B, C) of 6 students. Each group undertakes experiment over 30 minutes and write down the required data.
Purpose of the experiment: The laboratory session is to incorporate:
1) The practical acquisition of engine parameters and sensor data
2) Performing simple calculations and analysis on the collected data and comparing these values to theoretical predictions.
It is projected that this progression of activity would provide the ideal basis for the students to develop and understanding of the differences between the ideal and actual engine performance and behaviour.
This test is designed to provide a general indication of the performance of a 4 stroke petrol engine, and involves applying incrementally increasing loads to the engine at full throttle.
The engine will be allowed to stabilise after load is applied, and readings observed for the key engine parameters from the indicators mounted on the control console.
Assessment: This experiment will provide data for the experimental report
Requirements for Experimental Report assignment
Make sure that all sections below are covered. Some sections require you to copy and paste content from the Excel spreadsheet but remember to include relevant figures and tables in the text.
Section 1. Complete coversheet with name, student id, group no, date of experiment, summary
Section 2. Summary of Log-book experiment
Section 3. During experiment, enter experimental data in Table 1- indicate units and enter data as written directly from the console during experiment, and do not forget to include the ambient conditions (temperature, pressure and humidity).
Bring a printed version of this table to the experiment.
Add the complete raw data table to your report.
Section 4. Complete Table 2 using data from your supplied P-V diagram.
Section 5. Explain why and how various assumptions made to generate ‘ideal conditions' significantly over predict T2, T3 and T4 values.
Section 6. Explain how the knowledge of actual indicator diagram can help in explaining the significantly lower value of the overall brake thermal efficiency as compared to the ideal Otto cycle efficiency.
Section 7. Explain how this experiment has helped you to enhance your understanding of thermodynamics and highlight one aspect that you enjoyed most.
You will receive zero mark if you say this experiment has not helped you to enhance your understanding and if you enjoyed nothing.
If this is genuinely true then please see Dr Ransing ASAP.
Section 8. Include a copy of the "Calculations" tab of the Excel spreadsheet at the end of your report. Ensure all figures remain valid.
When you are finished your report, you can upload it to Blackboard either as a text-based pdf or as a word document. Remember to include your coversheet in the main document.
Tips
Section 4:
Your answer should include references to:
- Polytropic vs isentropic expansion and compression
- Difference between net work done and (Qin - Qout) forpolytropic compression and expansion.
- Use of constant Cv values at STP conditions
- The assumption that no heat is rejected during the combustion process
- 100% volumetric and combustion efficiency assumption
- Differences between idealised and real P-V diagram
Section 5:
Your answer should include:
- Energy audit with actual figures from your experiment
? Total fuel energy available [kW]
? Energy transferred to the working fluid [kW]
? Actual and theoretical indicated power [kW]
? Actual brake power [kW]
You should also refer to:
- How and why you need to calculate the polytropic compression index
- How can the following be predicted:
? Maximum temperature [K]
? Combustion efficiency
? Actual indicated power [kW]
Table 1 - Input of raw data
|
P1 (Ambient Pressure)
|
101.3
|
kPa
|
|
|
Target Torque [Nm]
|
Actual Torque [Nm]
|
RPM [1/min]
|
Inlet Temp
(T1) [ºC]
|
Exhaust Temp (T4) [ºC]
|
Volumetric Air Consumption (?a)
[L/min]
|
Fuel consumption rate (?f)
[kg/h]
|
|
1
|
0.00
|
0
|
2908
|
22.6
|
504
|
88
|
0.416
|
|
2
|
0.50
|
0.485
|
2896
|
22.6
|
504
|
86
|
0.472
|
|
3
|
1.00
|
1
|
2886
|
22.6
|
508
|
90
|
0.444
|
|
4
|
1.50
|
1.52
|
2856
|
22.6
|
511
|
99
|
0.527
|
|
5
|
2.00
|
1.985
|
2835
|
22.6
|
511
|
104
|
0.527
|
|
6
|
2.50
|
2.51
|
2800
|
22.6
|
514
|
116
|
0.499
|
|
7
|
3.00
|
2
|
2760
|
22.6
|
514
|
130
|
0.583
|
|
8
|
3.50
|
3.495
|
2671
|
22.6
|
512
|
141
|
0.638
|
|
9
|
3.60
|
3.625
|
2665
|
22.6
|
516
|
142
|
0.693
|
Table 2 - P-V Diagram derived data
Use the indicator diagram (PV diagram) supplied to obtain these values. The P-V curve will have been obtained with a target applied torque of 3.00 Nm.
Remember to add atmospheric pressure to convert gauge pressure to absolute pressure values.
|
|
Target Torque [Nm]
|
Actual Torque [Nm]
|
P1 [bar]
|
P2 [bar]
|
P3 [bar]
|
P4 [bar]
|
Indicated mean pressure [bar]
|
V3/stroke volume
|
|
7
|
3.00
|
|
|
|
|
|
|
|
Attachment:- Heat Engine Experiment.rar