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Li.U Lab Model 3 Pressure Test

Succesful Pressure Test Of The Updated Lab Model V3 From The Three Joint GREC Sustainable Groups Project at Linköping University


As flagged by the Linköping University Workshop the GREC Lab Model V3 was not fully assembled in time for final the project presentation. The three groups did a brave assembly after their presentation but before finishing their term. Unfortunately time was running out again and they did not achieve any results in their brief testings. After the term nilsinside AB was allowed to borrow the Linköping Lab Model during the summer season for debugging and updating in Varamon, Motala.

GREC Lab Model V3 one of four pressure sensors nilsinside AB
One of the four pressure sensors tested in the first GREC Lab Model V3 test at nilsinside AB

At nilsinside the the symptoms were analysed and systematic iterative work was done to adjust and seal the GREC LabModel v3 during June and beginning of July 2023. For every assembly it got a little bit better and the first acceptable pressure test (this one) was conducted the 11th of July 2023 using lungs and a plastic tubing.

GREC Lab Model V3 pressure test at nilsinside AB
The Green Revolution Energy Converter (GREC) Lab Model V3 with temporary plastic tubing. You may also locate the four pressure sensors.

During the first short test the LabModel v3 was operated by the Mechatronics group software "Kombinerad_kod.ino" with a WGV revolution at 2 Hz (120 RPM).

The software recorded the 4 pressure sensors simultaneously in their 4 different locations (Columns) WITHOUT any temperature difference between both of the heat conducting sides. The four graphs follow each other so well that they almost completely overlap. The Lab Model v3 finally appears to be without disturbing friction and also fairly tight.

GREC Lab Model V3 pressure test diagram
The Green Revolution Energy Converter (GREC) Lab Model V3 pressure test diagram with overlapping graphs

Ambient temperature: 19°C (292°K)
Temperature Gradient, ΔT = 0°C
Ambient pressure: 100 564 Pa
Maximum pressure in this test, P max: 115 977 Pa
Minimum pressure in this test, P min: 88 170 Pa
Pressure difference in this test, ΔP = 27 807 Pa (corresponds to an approximately 80°C heat gradient.)


• At the positions between 17 to 18 and 24 to 26 and 30 to 31 the tube is completely closed so the linear coefficient shows a small leak in the GREC. Hopefully the leak disappears when we tightly cover the shaft passage areas.
• In the position 12 - 13, 23 and 29, the variation between the values is larger. This may indicate a variation in response time which in turn may depend on sampling time in the I2C bus, software, processor frequency, sensors etc.

We will follow up by a few tests with a minor temperature gradients to see if the graphs still overlaps. It might be that they separate proportional to the revolving speed

The Technology

In thermodynamic terms the GREC is a closed system with a moving boundary where the GREC converts heat energy to kinetic energy. The GREC heats up and cools down its internal large sliced WGV efficiently, fast and repetitively, resulting in internal pressure changes.
These internal pressure changes are used by its moving boundary to generate kinetic energy. You may think of the GREC as a revolving Carnot heat engine controlled by computer logic. Please find the theoretical presentation of the GREC on this link:
GREC Theory Presentation

The GREC is a new technological solution to tackle climate change and luckily there are three groups at Linköping University this spring that thrive on the challenge of a transition to fossil free energy systems. They will construct and build the GREC Lab Model v.3 as a step in a climate positive project that will need several research projects over time...
Please feel free to call or email:

Contact information at nilsinside AB
Nils Karlberg, tel +33 608 53 15 93, theory & technical questions
Sophia Karlberg , strategy & admin questions

The GREC Project