[foodhackingbase] [incubator] Re: update on the experimental incubator testing

Wed Jun 11 14:38:16 CEST 2014

I use two big aluminum heatsinks 25x10cm, 5cm high, with two 90W peltiers 
inbetween, with lots of grey heatsink paste. Initially I used a plate of 3mm 
MDF to isolate the two heatsinks from eachother, but that started soaking 
the oil from the paste and the paste got dry and brittle. I initially used 2 
7cm fans on each heatsink. I managed to only cool 4C down. After a rebuild I 
made the inbetween plate from HPL (high pressure laminate). And put 9cm fans 
on. The fans use 2W each. I can not imagine the 4W on the inside of the box 
is responsible for the fact that it slightly heats now. I did try switching 
on only one peltier - this resulted in constant temperature. The outer 
heatsink is definitively hot.

The two heatsinks and inbetween plate are kept together by 4 nylon screws 
now. Before I used 3mm metal rods, but I feared that was the heat leak.

I ordered some 60W peltiers and will let you know if that changes stuff. It 
just feels to me the outer heatsink is too hot and should be cooled more by 
fans, and this is the problem we face. I will try getting a big room fan 
(220V) and force cooling the outer heatsink to see if that makes a 
difference.

Marcel

-----Original Message----- 
From: Frantisek Algoldor Apfelbeck
Sent: Wednesday, June 11, 2014 3:03 AM
To: experimental incubator mailing list
Cc: Sven Uckermann ; Lars Möller ; Philipp ; Food Hacking Base mailing list 
; Arnd
Subject: [incubator] Re: [foodhackingbase] update on the experimental 
incubator testing

Hi Sven and all,
thanks for the thought. Below is link to the picture of the
heating/cooling unit set up

https://foodhackingbase.org/wiki/File:Experimental_incubator_mamut_tamna_2_1_cool_box_cooling_brain_wires_800_600_faa08062014.jpg

it is the outer part but the internal system is exactly the same. More
info on the prototype is here

https://foodhackingbase.org/wiki/Experimental_Incubator/2.1_mamut_tamna

As you can see there is quite pretty decent heating sink there
(connected by thermalpaste) which is not getting too hot or cold so the
distribution of the heat/cold enhanced by the fan is I think quite
reasonable. However your note made me realized what is most likely the
actual problem which I should see straight away. It looks like that the
fan which we use to "distribute" the "cold" produced by peltier is doing
it's job but because it is basically small electric engine it is of
course producing heat. So the final drop in temperature is corresponding
to the cold produced by the peltier minus the heat produced by the fan.
It looks like that the production of the heat by the fan is quite
substantial therefore the drop in temperature is just small. I've
received word from Marcel who installed even stronger system - more
powerful peltiers and it looks like that instead of cooling he is
actually heating, is it so Marcel? That may be confirming the idea which
I mentioned above.

What I wonder is if we can somehow minimize the heat production by the
fan which seems to me we need to distribute the cold from the peltier,
or do we? We need to cool the hot side otherwise it burns but can we
leave the cold side alone? Would the dissipation of cold be sufficient?
Or shall we use some another system of air circulation or just less
powerful fan?

Thanks for any thoughts this one is quite a challenge I think.

Sincerely,

Frantisek

On 2014-06-10 15:37, Sven Uckermann wrote:
> Hi,
> the problem with cooling and heating is that the stuff inside (aka
> your cultures etc) are often water based and as such an great material
> for taking heat .. but the air as such is a good insulator so getting
> rid of the heat of the peltier while cooling seems to be your problem
> ... you might want to add some thermal mass (copper or such) to the
> "outside" of your peltier .. so it can cool more .. if both sides of
> the peltier are the same temperature this things dosn't work to great.
>
> Greetings Sven
>
> 2014-06-07 15:06 GMT+02:00 Frantisek Algoldor Apfelbeck
> <algoldor at foodhackingbase.org>:
>
>> Hi to all,
>> I've uploaded graphs of the latest Marcel's and my testing of the
>> experimental incubator:
>>
>>
> https://foodhackingbase.org/wiki/Experimental_Incubator/2.1_mamut_tamna
>> [1]
>>
>> I will play with them more later on at the moment proper legends are
>> missing and the scales of all graphs are not same which may make
>> understanding of what is the performance bit hard. Also I need to
>> add detailed description of the hardware like volume of the
>> chambers, power of the pelties etc.
>>
>> Especially Marcel's experiment shows the fine heating potential
>> hitting over 70C, still the cooling is not doing too well. My
>> heating results are satisfactory hitting around 50C for culturing
>> many fermented products which I and we here are into, cooling is
>> definitely not. I still do not know how to switch polarity of the
>> peltier so the cooling/heating would be done automatically by
>> program. I need to buy good h-bridge (ideas?) or make one or use
>> some set of relays (how to do that?). I'm looking forward for
>> comments!
>>
>> I wonder if Lars could think about what may be the issue with the
>> cooling because the Warpzone prototype is doing much better, going
>> down to around 8C at over 25C outer temperature, right?
>>
>> Many thanks for any info, I will be working on this in the next few
>> days, I just cut my hand so no field work for a while and soon I
>> will be able to type again properly :-)
>>
>> Sincerely,
>>
>> --
>> Frantisek Algoldor Apfelbeck
>>
>> biotechnologist&kvasir and hacker
>>
>> http://www.frantisekapfelbeck.org [2]
>>
>> "There is no way to peace, peace is the way." Mohandas Karamchand
>> Gandhi
>>
>> Disclaimer - there are other people who have access to this email
>> account, please be aware of that it is part of the design. For
>> "highly private communication" use algoldor at yahoo.com
>> _______________________________________________
>> foodhackingbase mailing list
>> foodhackingbase at lists.hackerspaces.org
>> http://lists.hackerspaces.org/mailman/listinfo/foodhackingbase [3]
>
>
>
> Links:
> ------
> [1] 
> https://foodhackingbase.org/wiki/Experimental_Incubator/2.1_mamut_tamna
> [2] http://www.frantisekapfelbeck.org/
> [3] http://lists.hackerspaces.org/mailman/listinfo/foodhackingbase

-- 
Frantisek Algoldor Apfelbeck

biotechnologist&kvasir and hacker

http://www.frantisekapfelbeck.org

"There is no way to peace, peace is the way." Mohandas Karamchand Gandhi

Disclaimer - there are other people who have access to this email
account, please be aware of that it is part of the design. For "highly
private communication" use algoldor at yahoo.com 