Lots to report from the last few days
1- Difference between sensors
We learned from all the additional sensors we installed this week that our temperature control int eh room was very good at controlling the temeprature at the one point of the sensor. The other temperature sensors shows some variation throughout the day, though. At least that explains some 12 hour trends we saw during our previous runs. Going forward we will be more careful about that.
The graph below illustrates this point. The cell temps all dropped (no power applied to cell at all), while temperature where the T_ambient sensor is located stays in a tight range.
Here we see the Air temps at the top of the hood run warmer than the cell temps and the T_ambient sensor.
We were suspicious of the new, very inexpensive thermocouples we were using to read the air temps. This is what Malachi learned about them:
To gauge the accuracy of our new thermocouples we took T_A3 and submerged it into a hot water bath and boiled the water. This took place around 10:05 AM local time. The resulting temperature was 100 C (+-0.05 C).
Then, to gauge the precision we took all three ambient thermocouples (T_A1-3) and brought them to the same point. We isolated them from each other in 1 inch by 1/4" diameter individual copper tubes. These three tubes were then put in a larger copper tube with tape on the ends to restrict air flow. Then we waited and the resulting temperatures were within 0.05C of one and other. We can safely say the new thermocouples have an accuracy of +-0.05C and a precision between sensors of +-0.05C.
2 - Installing cells vertically with air flow
Per suggestions from Celani and Ed Storms and a few others on the blog, we are trying some runs with the test cells oriented vertically. The idea is that the air flow outside the cell and the convection cycles inside the cell with make the inside glass and outside glass temps more consistent and usful for indicating actual heat flow. Dr Storms would like to see us using the temperature difference across the glass as an isoperibolic calorimeter.
Much work was done. More pictures and video to come below.
3 - Repaired pass through, cracked wire support
Yesterday, as we installed fresh NiChrome wires and Bare Isotan wires into the cells, one of the copper wires glued into the passthroughs broke. It broke right up close to the pass through so we couldn't solder or attach to it. We decided to attempt a repair. We heated the passthrough with a propane torch to break down the epoxy. It worked, but it was a very stinky success and there was black gooey epoxy all over that came off only with acetone and a tiny buffer wheel. We also cracked a Macor support, but it was only a tiny piece of the corner that came off. We added a dot of epoxy where it meets the flange and called it good.
4 - AFC - Getting ready to test - Insulated stainless cell
Early test are looking promising on the air flow calorimeter. They are mostly informal, so far. We have been very busy getting the two cells mounted in the vertical apparatus, but we did manage to put together another core that will serve inside a stainless shell for inside the Air Flow Calorimeter. The one on the right will be in the calorimeter. We will insulate the stainless shell of the shell in 2 inch (5cm) of mineral wool insulation so it will require very little energy input to get up to working temperature.
Here are the details of the wire pass throughs.
5 - New wires arriving next week
In the reworking process, we decommissioned the first Celani wire we had used. We will try to take some pictures of it soon.
Next week we will receive some new Celani wires to put into these fun toys. More on that when they get here. We're hoping to have enough calibrations done to be able to pop them in and have some active runs over New Years.
6 - The Monster-Twin-Cell-Vertical-Apparatus and the Calibration Routines
Here is the groovy stuff going on right now. We just assembled and commissioned this dual cell apparatus.
Cell 1.0 - The Mica/Quartz glass cell with NiChrome on the blue power channel and Isotan wire on the red power channel.
The Macor/Pyrex cell with NiChrome on the blue power channel and Isotan wire on the red power channel.
Isn't that an intimidating mess of sensors?
The data collectors are set on this new shelf under the hood. This isolated their heat output from being directly on the cells.
The data is streaming. We are doing a 7 step up, 7 step down calibration. Both cells are at 0.5 bar and will do this calibration cycle twice. Then I will up the pressure to 1 bar and perform that calibration 6 times to get a good idea of the variability and error bars.
Happy holidays and happy data watching.
Update #2/3 (now with video)
Just in case the world did end, the EU team wanted to have a bit of fun on their last full day together in Switzerland, so, in a break from the normal schedule, they did a Mizuno type experiment.
On a serious note, we decommissioned the first EU active 360 layer Celani wire from its cell and Mathieu will be taking that back to France to, as planned, see if anything can be seen under the Scanning Electron Microscope and other tests.
After which, we drank "LA FIN DU MONDE" beer at the university bar - which is French for "The end of the world"
If tomorrow comes - we hope you can join us in our continuing journey.
Happy Christmas Everybody!