Thursday 25/04/2019 Weekly blog update

updates since last week: I have included another temperature sensor to monitor the cool side of the engine and updated my labview code. This allows for calculating the temperature difference which provides interesting insight into the engines performance.


Also, I have ran some tests with the engine to observe how my labview code is performing. All my sensors are operating as they should and are providing good data. Most importantly, I am able to accurately capture a given stirling cycle data (see below).


From my early tests there were two issues that needed addressing. Firstly, I needed to ensure that I am using the correct SI units for my calculations. My graph above shows volume in cubic centimetre vs pressure in kilo pascals. This has been updated to volume in cubic meters and pressure in pascals.

The second issue was the implementation of the greens theorem formula for polygon area calculation. The results were widely inconsistent. As a result I am using a different approach. I am dividing the polygon into two curves, an upper and a lower. I do this by selecting the smallest volume value in my array of PV data, and including all the following values up to the highest, then allocating this as my lower curve. Everything left then forms my upper curve in ascending order. Then I enter both curves into a subvi which calculates the area under each curve by performing the following function (see below).


Labview implementation:



In the following week I will be improving different aspects of my code if needed and fine tuning all the processes. Then I intend to complete the testing phase which should only take a few hours, during which, data will be extracted for analysis and presentation. 


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