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Solar oven for pasteurization?


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#1 SelfTransformingMachineElf

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Posted 02 May 2021 - 06:33 PM

I'm considering building a solar oven for pasteurization.  A typical solar oven I would expect to provide a drying experience, and staying down at 160°F would also be a bit of a design challenge.  But it sounds like a fun one!  Anyone ever tried or thought about it?


Edited by SelfTransformingMachineElf, 02 May 2021 - 06:33 PM.


#2 TVCasualty

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Posted 02 May 2021 - 08:27 PM

I've drawn up a few designs for medium to large volumes of bulk substrate involving old sliding glass doors and straw bales, but always talked myself out of actually building one.

 

That's because in order to ensure I didn't waste a day's work and a lot of substrate I'd need to incorporate a conventional pasteurization method anyway as a backup, because clouds happen. And once the Sun sets, it begins to cool back down. So if you don't get the heat you need by then and have no other way to heat things up then you're screwed. Solar-thermal type panels will still accumulate heat under cloudy skies (to a point) but not enough to pasteurize a significant volume of mass unless there are a lot of panels in use (or you're using evacuated tubes). Depending on where you're at that might be a significant problem, or not much of one at all.

 

I guess it all still ultimately depends on how much mass you're talking about pasteurizing and what your budget for solar tech is.

 

One option worth considering is evacuated-tube solar collectors. They can generate high-pressure dry steam (≥150℃) and are far more efficient under cloudy skies than flat-plate collectors.

 

Edit: It can work, but only during certain time of year, depending on the weather.


Edited by TVCasualty, 02 May 2021 - 08:33 PM.

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#3 Oldpunk

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Posted 02 May 2021 - 10:00 PM

Yeah but it gets wicked hot in a solar oven. Pasturizing in my oven I only went 170deg for 2 1/2 hrs. I think that's easily doable on a decent day. We built one at a place I worked and it was pretty easy. And I've built some homemade hot air panels and they reach around 200 deg.

I think it's a cool idea if you've got the ambition. And you could always bake actual food if you want. It was a cool experience to make something in it the first time.

#4 Oldpunk

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Posted 02 May 2021 - 10:05 PM

Honestly I think the hard part would be not overheating. You would need some active ventilation when it hit 165-170 and you gotta watch the temp tolerances on those vent fans.

#5 bezevo

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Posted 02 May 2021 - 11:10 PM

i'm guessing keeping stable 160f  temp  would be an almost impossible engineering challenge .

 

i myself considered saving energy costs by running a power cord to my neighbors  deck electric plug in for my gigantic electric hot plates for my PC's and my two electric roasters i use for pasteurizers ..................but i ruled that out  under

......i would probably  get caught clause.......

and really piss off the neighbors .

it seemed like  a good idea but it was a flawed plan .

 

BEZ



#6 pharmer

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Posted 03 May 2021 - 12:38 AM

maybe you could pair the solar oven with a solar powered fan

 

find the right balance of solar gain and moving air and might solve the problem

 

with an arduino gadget you could set the fan to turn on anytime the temp got to XXX degrees

 

of course both of these ideas are moot if your intent is to use no gadgets or electronics, but if you're trying to do something off-grid they'd get it done



#7 SelfTransformingMachineElf

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Posted 03 May 2021 - 07:09 AM

My intent isn't concerned with the use gadgets/electronics more-so than to use as little power as possible.  In fact, I'm a big gadget/tech/IoT fan.

 

Per the rest of the discussion - I do think staying COOL enough will be a bigger problem than not getting hot enough.  A few things to try.  Fan would definitely be the first.  And then if I'm really reaching too high of temperature, I could always actively provide shade.

 

I've already got plans to make a solar distiller (easy project), so I think this may be next.  Gotta make some space for it though.


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