[Stoves] Inner color of combustion chamber?

[Dean Still]

Hi G,

Just wondering if black on the inside of a metal combustion chamber and
silver on the outside is a beneficial combination.

Best,

Dean

On Sat, Apr 25, 2015 at 4:34 PM, Bamboo Science Group <
greg at bamboosciencegroup.com> wrote:

> Dean
> Emissivity varies with different metals and their oxides. A refractory
> metals like Tungsten or Niobium are wicked expensive. So are you asking
> about a coating on a ceramic substrate or an actual metal ( alloy)?
> G
>
>
>
>
>
> Sent from my iPad
>
> On Apr 25, 2015, at 6:36 PM, Dean Still <deankstill at gmail.com> wrote:
>
> Hi All,
>
> We were wondering if an inner refractory metal black wall would absorb the
> IR (get very hot) and then emit back into
> the fire. The outside of the metal wall would be shiny and then not emit
> very much into the stove body?
>
> Best,
>
> Dean
>
> On Fri, Apr 24, 2015 at 3:12 PM, Bamboo Science Group <
> greg at bamboosciencegroup.com> wrote:
>
>> Dean
>> Great topic
>> When I was designing solar thermal panels for INCO in 1979, we used a
>> coating (selective) process (chrome oxide spinel that had a alpha (
>> absorptivity) of 0.9 and and epsilon ( emissivity) of 0.04) on stainless
>> steel that allowed it to perform at parity with a black oxide on copper (
>> fin and tube).  The parity was achieved despite the overwhelmingly superior
>> conductance of copper versus s/s.
>> The high alpha allows absorption of the short wave solar radiation and
>> the low epsilon slows the longer wave radiation emission in this flat plate
>> solar collector application. These "selective" surfaces have cavernous
>> surface area structure, utilizing the peaks and valleys of the coating to
>> slow down the emissivity of the longer wave radiation.
>>
>> So you want an low emissivity coating for your refractory material to
>> reduce ( inhibit) the black body radiation. SERI could certainly help out
>> in this area as they are acquainted with high-temperature selective
>> coatings for their work on concentrating collectors.
>>
>> Sent from my iPad
>>
>> > On Apr 24, 2015, at 5:07 PM, Dean Still <deankstill at gmail.com> wrote:
>> >
>> > Hi All,
>> >
>> > At the Aprovecho weekly meeting we were discussing how to improve
>> performance in a Rocket stove. We were wondering about radiation.
>> >
>> > Would temperatures rise if the inside of the refractory metal
>> combustion chamber was black and the outside shiny?
>> >
>> > Best,
>> >
>> > Dean
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