[NatureNS] Stove Blacking and heat transmission

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From: Henk Kwindt <hjcbatl@gmail.com>
Date: Thu, 28 May 2020 20:17:49 -0300
References: <6d20673a-3793-c7b2-dbc7-f1a8950ae32b@glinx.com>
To: "naturens@chebucto.ns.ca" <naturens@chebucto.ns.ca>
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 wood stove and spins faster as the stove 

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I couldn=E2=80=99t stay behind so dug into the Christmas box and found =
the angels in original box!
Besides the headings that you quoted it also states: Manufactured by =
Automatindustrier AB Gefle- Sweden.
Henk

> On May 27, 2020, at 10:23 AM, David Webster <dwebster@glinx.com> =
wrote:
>=20
> Hi again Henk & All,
>=20
>     Original box found; says "Swedish Angel Chimes" on main panel: =
"Angel Chimes A Product of Swedish Handicraft" on end tab.=20
> YT, DW, Kentville
>=20
> -------- Forwarded Message --------
> Subject:	Re: [NatureNS] Stove Blacking and heat transmission
> Date:	Wed, 27 May 2020 08:44:56 -0300
> From:	David Webster <dwebster@glinx.com> <mailto:dwebster@glinx.com>
> To:	naturens@chebucto.ns.ca <mailto:naturens@chebucto.ns.ca>
>=20
> Hi Henk & All,    It is one of these effects which must be seen to be =
believed; the difference between 'black and white' (via dull grey). That =
Swedish connection may be in error. Will be on the lookout for the =
original package likely about 50 years old.
>=20
> Dave W.
>=20
> On 5/26/2020 9:13 PM, Henk Kwindt wrote:
>> Hi Dave and All,
>>=20
>> I don=E2=80=99t really have anything to add to your explanation but I =
thought it interesting that you have one of those =E2=80=9Cangel =
carousels=E2=80=9D!
>> We have had ours for at least 40+ years, they were quite popular in =
The Netherlands in the 60s, didn=E2=80=99t know they came from Sweden.
>> Ours is packed with other Christmas decorations so it is being placed =
on the stove every year in Dec.
>> We have not used the candles to =E2=80=9Cpower=E2=80=9D it for a long =
time.
>> Since we have a more modern high efficiency stove the black top is =
not directly accessible so I won=E2=80=99t be able to repeat your =
experiment.
>> Henk Kwindt, Cow Bay, NS.
>>=20
>>=20
>>=20
>>> On May 26, 2020, at 7:47 PM, David Webster <dwebster@glinx.com> =
<mailto:dwebster@glinx.com> wrote:
>>>=20
>>> Hi Steve & All,
>>>=20
>>> No my mill is powered entirely by upward flow of warm air; a thin =
circular sheet of brass clipped to form eight vanes which slope downward =
to the left. This fan consequently turns near side to the left. =
(Clockwise viewed from above).
>>>=20
>>> The original unit, made in Sweden, was powered by candles and =
intended as a Christmas table decoration.
>>>=20
>>> The fan is supported by a brass plate with three arms on each of =
which an angel hangs and a brass rod hanging from each angel rings a =
chime as it turns.
>>>=20
>>> I just stuck the working parts in a support made from a length of =
burned out oven element, bent to be stable with the filling removed from =
the vertical end by tapping.
>>>=20
>>> Just to confuse matters; note that what we call clockwise (down on =
the right side) is counterclockwise from the clock's viewpoint.
>>>=20
>>> YT, Dave W.
>>>=20
>>>=20
>>> On 5/26/2020 5:53 PM, Stephen Shaw wrote:
>>>> Hi Dave,
>>>> I=E2=80=99m not familiar with your named device or its principle of =
operation, but we too have a small windmill that simply rests on top of =
our (also black) wood stove and spins faster as the stove heats up. It =
works as a Peltier device, with parallel hot and cold junctions built =
into a short aluminium tower, the top of which is an air-cooled heat =
sink. I think it cost ~$130 some years ago. The =E2=80=98hot' side of =
the Peltier junction faces down to the hot stove top upon which the =
frame rests, while the =E2=80=98cold' side is uppermost, and its heat =
sink is cooled partly by the little rotating fan and partly by =
radiation. With enough heating differential, the Peltier effect =
generates a small current which is enough to turn a small DC motor that =
carries the fan.
>>>> Is this like your device? If so, you may have simply have cleaned =
and in effect flattened the stove top a bit so the base of the device =
makes better thermal contact with the Al base of the windmill, though =
the black-body improvement should help a bit. A better solution in my =
case and maybe yours would be to apply a thin layer of heat-sink =
compound to the base of the tower. This is a messy paste based on zinc =
oxide, used standard in electronics to attach a power transistor to an =
aluminium or copper heat sink, while at the same time providing =
electrical insulation. It would certainly enhance heat conduction to our =
windmill, but the compound is white, sticky and difficult to remove once =
applied: I would become locally unpopular if I so disfigured our black =
stove top, so I haven=E2=80=99t yet risked the experiment.
>>>> Steve
>>>>=20
>>>> On May 25, 2020, at 7:55 PM, David Webster <dwebster@glinx.com> =
<mailto:dwebster@glinx.com> wrote:
>>>>> Dear All,
>>>>>=20
>>>>> I heat the house mostly with wood burned in a fireplace insert =
and,
>>>>> apart from some air circulation in under the fire box, up behind =
it and
>>>>> out over the top, most heating is radiant off of the top.
>>>>>=20
>>>>> For decades I have used a Swedish Christmas heat mill, sold for
>>>>> candles, which I adapted for stove top use, as a measure of heat =
release
>>>>> rate. In recent decades it turned less frequently and for several =
years
>>>>> not turned at all even with a brisk fire so I suspected wear and
>>>>> increased friction at pivot points.
>>>>>=20
>>>>> The stove top had become dull grey in color so to improve
>>>>> appearance I located a source of blacking last fall but it could =
be
>>>>> applied only to a cold stove so was applied to the top, on first =
recent
>>>>> warm morning this spring, and the increase in heat radiation from =
the
>>>>> top was dramatic. With just a token fire that Swedish heat mill =
was
>>>>> spinning full tilt !
>>>>>=20
>>>>> This I assume was a practical demonstration of increased radiation
>>>>> from a black surface (Black Body Radiation ?). And all along I had
>>>>> imagined that stove blacking was just for appearance.
>>>>>=20
>>>>> Yt, DW, Kentville
>>>>>=20
>>>>>=20


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