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Varamon Heat and Pressure Test 2023-08-02 20:20 of the Li.U Lab Model v3

Another Heat And Pressure Test Of The Updated Li.U Lab Model V3 From The GREC Sustainable Groups Joint Project at Linköping University


The collaborative efforts of three candidate groups at Linköping University Mechanical Engineering during the spring term of 2023 led to the construction of the GREC LabModel version 3, an achievement for empirical research. Subsequent preparations during the summer of 2023 paved the way for empirical testing to relate theoretical understanding and earlier simulations to real-world observations.
After fitting a tight peripherial cork-rubber gasket in July 2023 a pressure test was done. With the Lab Model closed system in equilibrium with all its inner surfaces at ambient temperature 19°C (292K) and the Stepper Motor revolving its Work Generating Volume (WGV) at 2 Hz (120 RPM) the closed system was pressurised by blowing in a plastic tube. This test was logged by the Li.U software simultaneously recording 4 pressure sensors strategically positioned in 4 different locations in cardinal directions around the LabModel v3. The four pressure graphs from the sensors follow each other so well that they almost completely overlap. The simultaneous pressure rise and fall throughout the entire LabModel v3 volume, even while the Revolving-Shutter is in motion, reinforced the distinction between the pressure and the flow phenomena. The graph also shows the grade of a Lab Model leak in two instances.

Conclusion: Notably, the uniform pressure values recorded by the pressure sensors added a new layer of significance to the experiment's outcomes.
These observations aligned closely with both earlier simulations and established thermodynamic theory, providing a strong basis for the reliability of the LabModel v3 as a research tool.
It is important to recognize that while these findings may present challenges to those unfamiliar with thermodynamics or flow mechanics, they hold profound implications demonstrating that pressure acts consistently across the entire closed system volume, even in the dynamic presence of the moving Revolving-Shutter.
In essence, this experiment stands as a cornerstone in the pursuit of understanding the pressure and flow dynamics of the LabModel v3, serving as a testament to it's capabilities and the dedication of GREC project. As the realms of theory and reality continue to converge through empirical investigation, this LabModel v3 will provide valuable insights that will undoubtedly shape the future of sustainable energy science, mechanical engineering, thermodynamics, fluid dynamics and related disciplines.
The pressure test shows that the Lab Model v3 revolving it's Work Generating Volume (WGV) at 2 Hz does not affect the pressure distribution. (And finally the Li.U LabModel v3 now appears to be without disturbing friction and also fairly tight.

The above pressure test led to a following revolving heat and pressure test on July 17, 2023. This following heat and pressure test was successful in demonstrating the heat transfer functionality of the system. Despite some limitations in the test setup, including a lower than expected revolution speed due to interference with the stepper motor control, the experiment provided valuable insights.
The recorded data from the pressure sensors revealed that the pressure inside the Work Generating Volume (WGV) and the "dead volume" remained consistent and identical to the total Lab Model V3 volume. This observation suggests that at the tested revolution speed, pressure changes were effectively distributed throughout the system.
The temperature gradient across the Lab Model V3 was maintained, with a temperature difference (ΔT) of 55°C between the warm and cold sides. Despite this gradient, the pressure graphs of different positions within the Lab Model V3 closely followed each other, even overlapping, indicating a consistent pressure distribution regardless of local WGV temperature variation.
It is worth noting that there was a small leak in the GREC system, which have affected the test results. This leak is expected to be addressed by better sealing of the shaft in future tests.
Conclusion: This heat and pressure test proves the heat transport to and from the Work Generating Volume. Despite some challenges and limitations in the test setup, the successful heat and pressure test of the Lab Model V3 provides valuable insights into the behavior of the GREC concept. The consistent pressure distribution and the understanding of the LabModel's operation contribute to the ongoing research of this technology.

Varamon Heat and Pressure Test 2023-08-02 20:20

A few measurements were recorded before returning the LabModel v3 to Linköping University. To get a better understanding of what the resulting diagram below reflects, one should consider these input conditions:

• The cork rubber gasket has changed the closed system internal air volume:
Total volume = 0.3471 l of which 69% is W.G.V = 0.2410 l and 31% can be considered "Dead Volume" = 0.1061 l
• Calculating n: Using the general gas law's empirical form p·V=n·R·T to calculate n by using the calculated volume V and recorded values for pressure p and T like n = (pV)/(RT)
Used starting values in the general gas law's empirical form pV=nRT are:
p = Ambient pressure: 98 115 Pa
V = 0.0003471 m³ (air)
n = 0.01399 [n = (pV)/(RT)]
R = 8.314
T = Ambient temperature: 20°C (293K)

GREC Lab Model V3 heat and pressure test at nilsinside AB
The Green Revolution Energy Converter (GREC) Lab Model V3 test diagram from 20230802-2020
showing the time and almost overlapping graphs from five pressure sensors at different locations:
North-East (Column blue in diagram), South-East (red in diagram), South-West (yellow),
North-West (green) and Ambient (brown). Rotation and sampling not in sync.

A split version of the Mechatronics group software "Kombinerad_kod.ino" was used resulting in a Work Generating Volume (WGV) revolution at about 3.7 Hz (222 RPM) and recorded 5 pressure sensors simultaneously. Four of the sensors were connected to different positions of the LabModel total volume and a fifth sensor recorded the ambient pressure outside the closed system as described in this link .
A temperature difference ΔT of approximately 74°C between the two heat conducting sides with 20°C at the bottom and between 90°C and 98°C at the top.
As in all tests so far the four graphs follow each other so close that they almost overlap.

Ambient temperature: 20°C (293K)
Cold side temperature: 20°C (293K)
Warm side Analogue thermometer 90°C (363K)
Warm side Digital thermometer 98°C (371K)
Estimated Temperature Gradient, ΔT = 74°C (74K)
Ambient pressure: 98 510 Pa
Maximum pressure in this test, P max: 99 658 Pa
Minimum pressure in this test, P min: 98 269 Pa
Pressure difference average in this test, ΔP = 1 388 Pa
Revolutions at approximately 3.7Hz (222 RPM)


Other factors to consider are:
• The model is not completely tight but the grade of the leak may be measured and calculated. This affects the measured values. The leak is suspected to be in the Revolving Shutter shaft roller bearing area. Hopefully not too complicated to cover.
• One heating element does not work. We have an external graphene packing as a distance between the conducting hot fins at heating elements level, so we assume that they carry almost the same amount of heat.
• The sampling is not in phase with the rotation. Sampling rate and revolving speed depends on I2C bus, the software and the Arduino processor frequency.
- The Li.U. software was split from one Arduino to two Arduinos to boost speed.
- One Arduino for collecting sensor data over I2C and presenting the logg.
- The other Arduino for turning the stepper motor certain revolutions at a certain speed and then to stop and also cut the power to the coils (to save the driver drv8825 from overheating)

• The relative humidity in Varamon was 45%, but considering that the volume in the GREC LabModel v3 had often been heated for quite long periods, we did not include this in the calculations.
Calculating the temperature of the volume in the table, it only varies by a few degrees. Both pressure and temperature (of course...) are at 1.4% of the 19% maximum possible for a temperature gradient of 74 degrees.

Conclusion: The Heat and Pressure Test 2023-08-02 20:20 proves:
More of the same which shows repeatability and that the thermodynamic laws also apply at a higher revolving speed. The leak causes the pressure to perform only a fraction but still testifies that the heat transfer to and from the WGV is working and the pressure is the same in the entire volume at each individual point in time.
- Yippee!

Future Tests

Further investigations, potentially involving sealing improvements, will provide additional insights into the Green Revolution Energy Converter behavior and performance.
• Cover the suspected leak and pump up the LabModel v3 and revolve. Start recording.
• Cover the suspected leak and revolve the LabModel v3 really slowly with a heat gradient to get a better understanding of minor leaks in relation to the heat transfer and the relation between the WGV and the dead volume.
• Cover the suspected leak and revolve the LabModel v3 with a constant heat gradient, in several sessions from slow to very fast to get a better understanding of the HTC.
Will the resulting graphs still overlap or will they separate at faster 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 and cools its internal large sliced Work Generating Volume (WGV) efficiently, rapidly and repetitively, resulting in internal pressure changes that generate volume change work.
You may think of the GREC as a revolving Carnot heat engine controlled by computer logics. Please find the theoretical presentation of the GREC on this link:
GREC Theory Presentation

The GREC is a new technical solution to tackle climate change and luckily there were technologist groups at Linköping University with the challenge of transitioning to fossil-free energy systems. They have contributed to several GREC climate-positive research projects over time.
Are you going to build the first commercial GREC? 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