me356: Reactor parameters [part 1]

I plan to build own reactor based on work of Dr. Parkhomov.

Parts are relatively very cheap and available. First from all I want to build heater that will work for longer periods.
Heater must be driven with electronics.

I plan to build control system based on PI(D) regulation with microcontroller so it can work without any additional stuff.
Maybe I will try DC with pulse width modulation to control temperature so it can work from a different power sources.

Heater Wire: I will start with Kanthal A1 wire or hopefully I can get Super Kanthal that is able to stand even 1900°C continuously.
Heater Ceramic tube: 1x ceramic with min. 99,7% Al2O3 - ∅D = 16mm, ∅d = 12mm, L = 80mm, Tmax = 1800°C
Reactor Ceramic tube: 1x ceramic with min. 99,7% Al2O3 - ∅D = 10mm, ∅d = 5mm, L = 290mm, Tmax = 1800°C
Reactor Ceramic filings: 2x ceramic with min. 99,7% Al2O3 - ∅D = 5mm, L = 100mm, Tmax = 1800°C
Thermocouple: unknown yet, maybe R, S or B?

Do you think that diameters of 10/5mm are fine? What do you suggest?

Thank you Dr. Parkhomov for perfect work, I hope you will continue!
Sharing your findings can make our world much better.

All tests should be done in a special room made by conrate so even fire or explosion should do nothing.
I want to control and observe the process remotely, at least 50m away from the reactor.
In case that gamma or neutron radiation will occur it will be not dangerous for us.

Stage 1. building the reactor that is able to stand at least 1200°'C for long periods (at least weeks) with atmospheric pressure (without fuel). When this criterium will be fulfilled, we can go to Stage 2. All data will be logged, especially temperatures for future comparison. In this stage TC calibration and PID regulation tuning will be performed.

Stage 2. testing reactor with fuel, with 12h temperature rampup to not exceed pressure - everything will be controlled by program, so it should be perfectly reproducible.
We will use opensource tools and hardware so everybody can possibly reproduce it later with little effort.

Stage 3. long term tests with fuel, trying to achieve the highest possible COP with SSM. Improvements in the control algorithm.

Stage 4. trying to harness heat for usefull usage to achieve the highest efficiency.

Well, I think that unexpectable behavior may be:
A) explosion because of high pressure
B) excess radiation
C) melting reactor - in this case CO2 extinguisher may be helpfull.

Regarding Fuel, what Nickel powder may be the best? I believe that it should be clean. Do you think that 10um particle size will be OK?
Vale Type 255 is approx. 3um.

I have measured, that fuel for the reactor costs only approximately $0.24! Thats awesome. I have Ni + LiAlH4 from local chemist laboratory.

OK, I've checked various solutions and it seems to me, that the best solution for controlling output power may be with Solid State Relay and PWM.
Alternatively we can use triac that will cut AC phases and thus can change output power.

But I think that SSR is the easiest solution that will just work with the best latency.

I will use thermocouple K type with 1300°C Tmax because of good availability and fine parameters.

Radiation measurement tool will be most probably Gamma Scout, because interfacing is quite easy and well documented.

I am very familiar with PWM and advanced PID regulations with adaptive tuning, so it should be quite easy for me - at least this part.

I hope I can start with Stage 1 very soon.

Could somebody tell me, what sealing cement for the heating coil do you recommend?
I can't find anything beyond 1200°C.

Thanks!

I have found Silicate based cements that are able to stand 1300°C. It is used for ovens and stoves, so I think it can work.

I am struggling with Fuel Container little bit at the moment.

Quote

The AGP fuel container was a stainless steel tube slightly smaller in diameter than the bore of the reactor tube. The length was about 50 mm ( note this was eyeballed from photo) The tube was sealed by heat-resistant cement.
The tube or the sealant had three small openings. These were necessary to release the pressure from the hydrogen which is generated as the LiAlH4 decomposes when the reactor is heated.

I dont know, if the whole reactor should be sealed so hydrogen "can't escape" at all. If AGP made 3 holes in the fuel container, then there is just little bit more room for the hydrogen gas. But still it can't escape. It will be blocked by ceramic fillers from both sides.

If it was 5cm long tube then there is lot of room for the air, so ceramic fillers can't push the air out. Was the fuel container sealed somehow first from both sides (with loaded fuel) and then inserted into the reactor?

Do you think that pressure is the key factor in the process? At least before melting point of the lithium.

Why do we need fuel container if the fuel can be placed directly to the reactor ceramic tube? Is it because of easier refueling?

Wow, many thanks for sharing the info!

To not destroy thermocouples I was planning (for the future) to make calibration inside the reactor tube and outside where temperature is not so high.
With some calculations about heat transfer in the material I can get hopefully precise temperature measurement from outside of the reactor.
So very naive calculation may be temp = temp_tc2 * 2; in case that temperature will be 2x smaller than in the core.
With this thermocouple can last for very long time.

Disadvantages:
- possible increased delay in getting temp of the core.
- decreased precision with same decoder.

Good, ceramic tubes arrived, everything is OK. Quality is perfect 99,7% Al2O3 and 1800°C guaranteed. Each tube including fillers is made of this material. Price for these tubes was $23, not bad. With higher quantity it can be much cheaper.

My heater will be made of:
∅D = 15mm, ∅d = 10mm tube, I have also ∅D = 16mm, ∅d = 12mm, but first one fits fine on the reactor tube.
20AWG (0.812mm) Kanthal A1 wire, 3569.8mm length (R = 10Ω), 66-67 wraps with 50-100mm total leg length (<3% power loss)
Wire sealed with a stove cement - based on water glass, 1300°C max. temperature.

Input Voltage 230AC @ 50Hz -> Transformer 2:1
-> Solid State Relay controlled by microcontroller with fast AC PWM or Phase Angle Triac circuit.

Max. output power cca 1210W @ 110V, 11A.

I am replicating the latest version.

If everything will be fine, calibration tests will be performed this week.
I am prepared for unsuccessfull tests, it is very normal.

But I strongly believe, that in the end, it will work.

Good news, I have found that company that is producing ceramic tubes is also producing special cements from very same material. So it is designed for this stuff.
Max. temperature: 1500°C

I have also programmed reactor controller with PID.

It supports few stages:
1. Slow pre-heating procedure to configured temperature.
2. Maintaining required temperature.
3. Self Sustain mode - TODO
4. Turn off

Everything can be controlled and configured remotely in real-time. All the data are remotely transmitted and also logged.

Next update - I will be using Gamma Scout geiger counter. I am very interested if I can see any radiation.

Interfacing will be done via USB so I can get logs easily and remotely.