V1.3 US Cells - Pre-calibration & Wires Installed

The US team has completed the Pre Calibration  (Step 0 in the V2.0 Protocol Table).  I know it is not very impressive sounding to say we got through step zero, but it is an important piece of validating how the cells perform and how reliably they measure before we put in the Celani wire to test it.  Getting a clean base line, or several in this experiment, is critically important.  

The main questions we asked were: 

1. How stable and consistent are the temperatures we achieved at certain powers?  How stable is it over a long period at a constant power?
2. How much difference was there between these identically manufactured cells?
3. How much difference in temperature readings are there when heating with one wire versus the other?
4. Do the temperatures achieved validate Celani's Stefan-Boltzman estimation of calorimetry?

Repeatability and stability

To answer this question we did several calibration cycles and calculated the confidence intervals based on the variability seen, just like previous experiments.  We last did these as a practice before adding the environment shell around the cells and measured confidence intervals after about 5 tests of roughly 1/2 a watt.  Steps 5.a and 5.b in the protocol will have us recreate these while the Celani Wires are in place.

The third part of Step 0 in the protocol is holding the power constant for 16+ hours and observing how much the key measurements changed over that time.  Below is a table summarizing the results.

Table of variation of temperature rise above ambient within the cell and on the glass over 20 hours at constant power (30 second averages of ~3 second data).

Difference between cells

After some early calibration tests showing large variation between the two cells, we engineered a better temperature controlled environment that would be less susceptible to air currents in the room changing.  The measured ambient in that environment is nice and stable, 

Difference between wires

Fit to Stefan-Boltzman

We found that, in our covered apparatus, at least, the Temperature vs Power In curve did not fit well to a constant factor.  I welcome anyone else to try to see how well they can make it fit.  

The latest calibration cycle: NiCr+Ox_130430_PreCal_CellA_CellB.xls

The Calibration cycle before that before we enclosed the cells:  NiCr+Ox_130408_Vac_Calib.xls

I, also, eagerly anticipate Mathieu's data because his dual cells are in open air in a large room, so the thermal radiation will be more applicable.

We have not really come to any conclusions about the meaning of all this.  Being that the cells are very close in design to Celani's original, I do think some comparisons can be made to the repeatability and stability his cell could have been expected to demonstrate.  Thoughts?

Pictures of 400 Layer Celani Wires being installed into the US Cells.

Yesterday, after completing the calibration cycles and analysis, Malachi installed one 400 layer wire into both test cells.  The images are added to this gallery.

After some much needed maintenance and cleaning, we finally had the time for Celani wire micrographs. Also note we figured out how to display a FIGURE KEY. This image is 434L (US cell B) treated wire with a small abnormality among the fuzzy topography typical of a Celani-treated surface. 

434L treated surface (US Cell B) demonstrating, on a microscopic scale, the fragility of the oxide surface. Slight bends and manipulations easily flake off the outer surface of the wire. The entire bulk of the treated constantan is very brittle; just ask Malachi!

A closer look at the 434 treated topography. 

The material used in these images is the very ends of excess wire, as we only have room in the cell to install ~85mm of Celani wire. The absolute tips of the wires  go untreated because they are covered by the electrical contacts used to resistively heat the rest of the bulk. This is a close shot of the very end of the 477L wire that previously burnt out in US cell B, just as a reference to the differing topographies. 

A larger view of the previous shot. 

Close topography of the 360L wire installed in US cell B after the latest active wire burnout. 

Buildup abnormality on 360L. 

Odd green tint to the nichrome?

Reassembly of the passthrough flange. 

Measuring the excess length of wire unused in cells but to be imaged with the SEM later. 

Checking the passthrough impedance prior to wrapping. The brittleness of the oxide-treated Celani wire makes re-wrapping around the mica a difficult and risky process. 

Slight discoloration at the tip of the Celani wire indicates where the wire was in contact with the power lead to heat it. These ~1cm sections of the wire were analyzed in comparison to their treated counterparts on the same length with SEM images (also shown in this gallery). 

Inspecting the active wires for irregularities or damage from shipping. Additionally the ends of the wire are scraped to remove the oxide layer and establish good electrical connectivity. 

The packets Celani ships the wires in have various information about their composition and treatment. This 477 layer treated wire was inserted into US Cell B, the control unit. 

Disassembly of the calibrated cells. 

Final assembly with the controlled air heater on it.  We have set the controller to about 30C.  It appears to be holding a constant temperature within 0.2 C.

The light weight cover over that allows access to the valves to each cell.

A view inside the air flow path.  The controlled, heated air enter into the triangle space between the cells.  From there, the air flow into the space at the head of each test cell and then along the cells, and out the back.

The ambient air sensors for each cell are shrouded in a white paper cone in order to keep any incident radiant heat from affecting the thermocouple.

Malachi fitting the shield around the cells in the vent hood.

Picture of the heater in place.

Cutting a hole for the controlled heater that will keep the air flow constant and just a little above the range of room temperatures so that a hot day won't throw the test off.

Malachi with the rough assembly ready to carefully fit the heater to and then fit around the cells.

Brief hand-sketch of the enclosure to help keep the V1.3 test cells in the USA in a constant temperature and constant air flow environment.

After some much needed maintenance and cleaning, we finally had the time for Celani wire micrographs. Also note we figured out how to display a FIGURE KEY. This image is 434L (US cell B) treated wire with a small abnormality among the fuzzy topography typical of a Celani-treated surface. 

434L treated surface (US Cell B) demonstrating, on a microscopic scale, the fragility of the oxide surface. Slight bends and manipulations easily flake off the outer surface of the wire. The entire bulk of the treated constantan is very brittle; just ask Malachi!

A closer look at the 434 treated topography. 

The material used in these images is the very ends of excess wire, as we only have room in the cell to install ~85mm of Celani wire. The absolute tips of the wires  go untreated because they are covered by the electrical contacts used to resistively heat the rest of the bulk. This is a close shot of the very end of the 477L wire that previously burnt out in US cell B, just as a reference to the differing topographies. 

A larger view of the previous shot. 

Close topography of the 360L wire installed in US cell B after the latest active wire burnout. 

Buildup abnormality on 360L. 

Odd green tint to the nichrome?

Reassembly of the passthrough flange. 

Measuring the excess length of wire unused in cells but to be imaged with the SEM later. 

Checking the passthrough impedance prior to wrapping. The brittleness of the oxide-treated Celani wire makes re-wrapping around the mica a difficult and risky process. 

Slight discoloration at the tip of the Celani wire indicates where the wire was in contact with the power lead to heat it. These ~1cm sections of the wire were analyzed in comparison to their treated counterparts on the same length with SEM images (also shown in this gallery). 

Inspecting the active wires for irregularities or damage from shipping. Additionally the ends of the wire are scraped to remove the oxide layer and establish good electrical connectivity. 

The packets Celani ships the wires in have various information about their composition and treatment. This 477 layer treated wire was inserted into US Cell B, the control unit. 

Disassembly of the calibrated cells. 

Final assembly with the controlled air heater on it.  We have set the controller to about 30C.  It appears to be holding a constant temperature within 0.2 C.

The light weight cover over that allows access to the valves to each cell.

A view inside the air flow path.  The controlled, heated air enter into the triangle space between the cells.  From there, the air flow into the space at the head of each test cell and then along the cells, and out the back.

The ambient air sensors for each cell are shrouded in a white paper cone in order to keep any incident radiant heat from affecting the thermocouple.

Malachi fitting the shield around the cells in the vent hood.

Picture of the heater in place.

Cutting a hole for the controlled heater that will keep the air flow constant and just a little above the range of room temperatures so that a hot day won't throw the test off.

Malachi with the rough assembly ready to carefully fit the heater to and then fit around the cells.

Brief hand-sketch of the enclosure to help keep the V1.3 test cells in the USA in a constant temperature and constant air flow environment.

SEM images being taken

An important part of the plan is to take SEM images of the  wire before and after.  Here you can see Wes inspecting a crack in the outer layer of the wire.  We'll publish the images soon after we get a good set.  Today, we can't figure out how to get the scale bar onto the CRT that faces the camera (we don't have the direct digitizer box).

Some days it feels like you have to build the sidewalk before you can take a walk.  We have been troubleshooting and improving the power supply control and the data collection a fair amount this week as we struggle to get data out of the experiments and verify it.