next message in archive
no next message in thread
previous message in archive
previous message in thread
Index of Subjects
Index of Subjects
--_000_EDE3990F6359409AB7DD4E4AFFE9C321dalca_
Content-Type: text/plain; charset="Windows-1252"
Content-Transfer-Encoding: quoted-printable
When it comes to blackbody radiation (and most things are pretty close to t=
hat if they are solid, liquid, or a dense gas) the amount of radiation that=
they emit at various wavelengths depends only on their temperature.
https://en.wikipedia.org/wiki/Black-body_radiation
When it comes to absorbing radiation, the colour does matter. In visible li=
ght, an object that looks red, does so because it absorbs all other wavelen=
gth in the visible part of the spectrum and reflects red light. An object t=
hat is black (in the visible part of the spectrum) will act a lot more like=
a blackbody (absorbing all wavelegths of visible light) while a white obje=
ct will reflect all wavelengths. The finish (matte or glossy) would also ha=
ve some effect. I expect that a black fan-like device on stove will be more=
strongly powered because the black allows it to absorb more infrared radia=
tion from the surrounding stove than a gray one, thus getting hotter.
Pat
On May 27, 2020, at 11:11 PM, N Robinson wrote:
CAUTION: The Sender of this email is not from within Dalhousie.
Re the blacking, when living in Montreal in an old house with hot water fur=
nace and radiators , I wondered at a certain point if the radiators would r=
adiate more heat if they were painted black. I couldn't find anything on t=
he net, probably because I did not know what question to ask. It was just =
a hunch, because black absorbs more heat; but this heat would be coming fro=
m the inside, so to speak...?
Still don't know but perhaps David's discovery holds the answer.
I did not paint them black and did not use my chimes to test anything.
Nancy
On Wed, May 27, 2020 at 10:44 PM David Webster <dwebster@glinx.com<mailto:d=
webster@glinx.com>> wrote:
Hi again Henk & All,
Original box found; says "Swedish Angel Chimes" on main panel: "Angel C=
himes A Product of Swedish Handicraft" on end tab.
YT, DW, Kentville
-------- 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>
Hi Henk & All, It is one of these effects which must be seen to be belie=
ved; the difference between 'black and white' (via dull grey). That Swedish=
connection may be in error. Will be on the lookout for the original packag=
e likely about 50 years old.
Dave W.
On 5/26/2020 9:13 PM, Henk Kwindt wrote:
Hi Dave and All,
I don=92t really have anything to add to your explanation but I thought it =
interesting that you have one of those =93angel carousels=94!
We have had ours for at least 40+ years, they were quite popular in The Net=
herlands in the 60s, didn=92t know they came from Sweden.
Ours is packed with other Christmas decorations so it is being placed on th=
e stove every year in Dec.
We have not used the candles to =93power=94 it for a long time.
Since we have a more modern high efficiency stove the black top is not dire=
ctly accessible so I won=92t be able to repeat your experiment.
Henk Kwindt, Cow Bay, NS.
On May 26, 2020, at 7:47 PM, David Webster <dwebster@glinx.com><mailto:dweb=
ster@glinx.com> wrote:
Hi Steve & All,
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).
The original unit, made in Sweden, was powered by candles and intended as a=
Christmas table decoration.
The fan is supported by a brass plate with three arms on each of which an a=
ngel hangs and a brass rod hanging from each angel rings a chime as it turn=
s.
I just stuck the working parts in a support made from a length of burned ou=
t oven element, bent to be stable with the filling removed from the vertica=
l end by tapping.
Just to confuse matters; note that what we call clockwise (down on the righ=
t side) is counterclockwise from the clock's viewpoint.
YT, Dave W.
On 5/26/2020 5:53 PM, Stephen Shaw wrote:
Hi Dave,
I=92m not familiar with your named device or its principle of operation, bu=
t 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 d=
evice, with parallel hot and cold junctions built into a short aluminium to=
wer, the top of which is an air-cooled heat sink. I think it cost ~$130 som=
e years ago. The =91hot' side of the Peltier junction faces down to the hot=
stove top upon which the frame rests, while the =91cold' 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 generate=
s 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 ef=
fect flattened the stove top a bit so the base of the device makes better t=
hermal contact with the Al base of the windmill, though the black-body impr=
ovement should help a bit. A better solution in my case and maybe yours wou=
ld 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 th=
e same time providing electrical insulation. It would certainly enhance hea=
t conduction to our windmill, but the compound is white, sticky and difficu=
lt to remove once applied: I would become locally unpopular if I so disfigu=
red our black stove top, so I haven=92t yet risked the experiment.
Steve
On May 25, 2020, at 7:55 PM, David Webster <dwebster@glinx.com><mailto:dweb=
ster@glinx.com> wrote:
Dear All,
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.
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.
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 !
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.
Yt, DW, Kentville
--
Nancy Robinson
514-605-7186
Patrick Kelly
159 Town Road
Falmouth NS B0P 1L0
Canada
(902) 472-2322
--_000_EDE3990F6359409AB7DD4E4AFFE9C321dalca_
Content-Type: text/html; charset="Windows-1252"
Content-ID: <77797E4D0F518048872B9ED7CBB383CE@CANPRD01.PROD.OUTLOOK.COM>
Content-Transfer-Encoding: quoted-printable
<html>
<head>
<meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3DWindows-1=
252">
</head>
<body style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-lin=
e-break: after-white-space; ">
When it comes to blackbody radiation (and most things are pretty close to t=
hat if they are solid, liquid, or a dense gas) the amount of radiation that=
they
<b>emit</b> at various wavelengths depends only on their temperature.
<div><br>
</div>
<div><a href=3D"https://en.wikipedia.org/wiki/Black-body_radiation">https:/=
/en.wikipedia.org/wiki/Black-body_radiation</a></div>
<div><br>
</div>
<div>When it comes to <b>absorbing</b> radiation, the colour does matter. I=
n visible light, an object that looks red, does so because it absorbs all o=
ther wavelength in the visible part of the spectrum and reflects red light.=
An object that is black (in the
visible part of the spectrum) will act a lot more like a blackbody (absorb=
ing all wavelegths of visible light) while a white object will reflect all =
wavelengths. The finish (matte or glossy) would also have some effect. I ex=
pect that a black fan-like device
on stove will be more strongly powered because the black allows it to abso=
rb more infrared radiation from the surrounding stove than a gray one, thus=
getting hotter. </div>
<div><br>
</div>
<div>Pat</div>
<div><br>
</div>
<div> </div>
<div><br>
<div>
<div>
<div>On May 27, 2020, at 11:11 PM, N Robinson wrote:</div>
<br class=3D"Apple-interchange-newline">
<blockquote type=3D"cite">
<div><!-- START CAUTION Box Code -->
<table align=3D"center" border=3D"0" cellpadding=3D"0" cellspacing=3D"0" st=
yle=3D"padding:10px 0 10px 0" width=3D"100%">
<tbody>
<tr>
<td style=3D"line-height:0px;font-size:0px;mso-line-height-rule:exactly;">
<table align=3D"center" border=3D"0" cellpadding=3D"0" cellspacing=3D"0" st=
yle=3D"background:#707372;background-color:#707372;width:100%;border-radius=
:5px;overflow:hidden;">
<tbody>
<tr>
<td style=3D"border-top:solid 8px #fbe122;padding:4px 8px;text-align:left;v=
ertical-align:top;">
<table role=3D"presentation" border=3D"0" cellpadding=3D"0" cellspacing=3D"=
0">
<tbody>
<tr>
<td align=3D"left">
<div style=3D"font-family:Arial,sans-serif;font-size:12px;line-height:16px;=
text-align:left;color:#ffffff;">
<span style=3D"font-weight:bold;font-size:12px;">CAUTION:</span> The Sender=
of this email is not from within Dalhousie.</div>
</td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
</td>
</tr>
</tbody>
</table>
<!-- END CAUTION Box Code -->
<div>
<div dir=3D"ltr">
<div dir=3D"ltr">
<div><br>
</div>
<div>Re the blacking, when living in Montreal in an old house with hot wate=
r furnace and radiators , I wondered at a certain point if the radiators wo=
uld radiate more heat if they were painted black. I couldn't find any=
thing on the net, probably because I
did not know what question to ask. It was just a hunch, because blac=
k absorbs more heat; but this heat would be coming from the inside, so to s=
peak...?
<br>
</div>
<div><br>
</div>
<div>Still don't know but perhaps David's discovery holds the answer.</div>
<div><br>
</div>
<div>I did not paint them black and did not use my chimes to test anything.=
<br>
</div>
<div><br>
</div>
<div>Nancy<br>
</div>
</div>
<br>
<div class=3D"gmail_quote">
<div dir=3D"ltr" class=3D"gmail_attr">On Wed, May 27, 2020 at 10:44 PM Davi=
d Webster <<a href=3D"mailto:dwebster@glinx.com" target=3D"_blank">dwebs=
ter@glinx.com</a>> wrote:<br>
</div>
<blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-=
left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<p>Hi again Henk & All,<br>
</p>
<div> Original box found; says "Swedish Angel Chimes=
" on main panel: "Angel Chimes A Product of Swedish Handicraft&qu=
ot; on end tab.
<br>
</div>
<div>YT, DW, Kentville<br>
</div>
<div><br>
-------- Forwarded Message --------
<table cellspacing=3D"0" cellpadding=3D"0" border=3D"0">
<tbody>
<tr>
<th valign=3D"BASELINE" nowrap=3D"" align=3D"RIGHT">Subject: </th>
<td>Re: [NatureNS] Stove Blacking and heat transmission</td>
</tr>
<tr>
<th valign=3D"BASELINE" nowrap=3D"" align=3D"RIGHT">Date: </th>
<td>Wed, 27 May 2020 08:44:56 -0300</td>
</tr>
<tr>
<th valign=3D"BASELINE" nowrap=3D"" align=3D"RIGHT">From: </th>
<td>David Webster <a href=3D"mailto:dwebster@glinx.com" target=3D"_blank">&=
lt;dwebster@glinx.com></a></td>
</tr>
<tr>
<th valign=3D"BASELINE" nowrap=3D"" align=3D"RIGHT">To: </th>
<td><a href=3D"mailto:naturens@chebucto.ns.ca" target=3D"_blank">naturens@c=
hebucto.ns.ca</a></td>
</tr>
</tbody>
</table>
<br>
<br>
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.<br>
<br>
Dave W.<br>
<br>
On 5/26/2020 9:13 PM, Henk Kwindt wrote:<br>
<blockquote type=3D"cite">Hi Dave and All,<br>
<br>
I don=92t really have anything to add to your explanation but I thought it =
interesting that you have one of those =93angel carousels=94!<br>
We have had ours for at least 40+ years, they were quite popular in The=
Netherlands in the 60s, didn=92t know they came from Sweden.<br>
Ours is packed with other Christmas decorations so it is being placed on th=
e stove every year in Dec.<br>
We have not used the candles to =93power=94 it for a long time.<br>
Since we have a more modern high efficiency stove the black top is not dire=
ctly accessible so I won=92t be able to repeat your experiment.<br>
Henk Kwindt, Cow Bay, NS.<br>
<br>
<br>
<br>
<blockquote type=3D"cite">On May 26, 2020, at 7:47 PM, David Webster <a hre=
f=3D"mailto:dwebster@glinx.com" target=3D"_blank">
<dwebster@glinx.com></a> wrote:<br>
<br>
Hi Steve & All,<br>
<br>
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).<br>
<br>
The original unit, made in Sweden, was powered by candles and intended as a=
Christmas table decoration.<br>
<br>
The fan is supported by a brass plate with three arms on each of which an a=
ngel hangs and a brass rod hanging from each angel rings a chime as it turn=
s.<br>
<br>
I just stuck the working parts in a support made from a length of burned ou=
t oven element, bent to be stable with the filling removed from the vertica=
l end by tapping.<br>
<br>
Just to confuse matters; note that what we call clockwise (down on the righ=
t side) is counterclockwise from the clock's viewpoint.<br>
<br>
YT, Dave W.<br>
<br>
<br>
On 5/26/2020 5:53 PM, Stephen Shaw wrote:<br>
<blockquote type=3D"cite">Hi Dave,<br>
I=92m not familiar with your named device or its principle of operation, bu=
t 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 d=
evice, with parallel hot and cold
junctions built into a short aluminium tower, the top of which is an air-c=
ooled heat sink. I think it cost ~$130 some years ago. The =91hot' side of =
the Peltier junction faces down to the hot stove top upon which the frame r=
ests, while the =91cold' side is uppermost,
and its heat sink is cooled partly by the little rotating fan and partly b=
y 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.<br>
Is this like your device? If so, you may have simply have cleaned and in ef=
fect flattened the stove top a bit so the base of the device makes better t=
hermal contact with the Al base of the windmill, though the black-body impr=
ovement 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 zin=
c oxide, used standard in electronics to attach a power transistor to an al=
uminium or copper heat sink, while
at the same time providing electrical insulation. It would certainly enhan=
ce heat conduction to our windmill, but the compound is white, sticky and d=
ifficult to remove once applied: I would become locally unpopular if I so d=
isfigured our black stove top, so
I haven=92t yet risked the experiment.<br>
Steve<br>
<br>
On May 25, 2020, at 7:55 PM, David Webster <a href=3D"mailto:dwebster@glinx=
.com" target=3D"_blank">
<dwebster@glinx.com></a> wrote:<br>
<blockquote type=3D"cite">Dear All,<br>
<br>
I heat the house mostly with wood burned in a fireplace insert and,<br>
apart from some air circulation in under the fire box, up behind it and<br>
out over the top, most heating is radiant off of the top.<br>
<br>
For decades I have used a Swedish Christmas heat mill, sold for<br>
candles, which I adapted for stove top use, as a measure of heat release<br=
>
rate. In recent decades it turned less frequently and for several years<br>
not turned at all even with a brisk fire so I suspected wear and<br>
increased friction at pivot points.<br>
<br>
The stove top had become dull grey in color so to improve<br>
appearance I located a source of blacking last fall but it could be<br>
applied only to a cold stove so was applied to the top, on first recent<br>
warm morning this spring, and the increase in heat radiation from the<br>
top was dramatic. With just a token fire that Swedish heat mill was<br>
spinning full tilt !<br>
<br>
This I assume was a practical demonstration of increased radiation<br>
from a black surface (Black Body Radiation ?). And all along I had<br>
imagined that stove blacking was just for appearance.<br>
<br>
Yt, DW, Kentville<br>
<br>
<br>
</blockquote>
</blockquote>
</blockquote>
</blockquote>
</div>
</div>
</blockquote>
</div>
<br clear=3D"all">
<br>
-- <br>
<div dir=3D"ltr">
<div dir=3D"ltr">
<div>
<div dir=3D"ltr">
<div>
<div dir=3D"ltr">
<div>
<div dir=3D"ltr">
<div>
<div dir=3D"ltr">
<div>
<div>Nancy Robinson<br>
</div>
</div>
514-605-7186<br>
<br>
</div>
<div><br>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</blockquote>
</div>
<br>
<div><span class=3D"Apple-style-span" style=3D"font-size: 12px; ">
<div style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line=
-break: after-white-space; ">
<span class=3D"Apple-style-span" style=3D"border-collapse: separate; color:=
rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal;=
font-variant: normal; font-weight: normal; letter-spacing: normal; line-he=
ight: normal; orphans: 2; text-indent: 0px; text-transform: none; white-spa=
ce: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing=
: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-ef=
fect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;=
">
<div style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line=
-break: after-white-space; ">
<span class=3D"Apple-style-span" style=3D"border-collapse: separate; color:=
rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal;=
font-variant: normal; font-weight: normal; letter-spacing: normal; line-he=
ight: normal; orphans: 2; text-indent: 0px; text-transform: none; white-spa=
ce: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing=
: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-ef=
fect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;=
">
<p style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-=
left: 0px; ">
<font face=3D"Courier" size=3D"3" style=3D"font: normal normal normal 12px/=
normal Courier; "><br class=3D"Apple-interchange-newline">
Patrick Kelly</font></p>
<p style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-=
left: 0px; ">
<font face=3D"Courier" size=3D"3" style=3D"font: normal normal normal 12px/=
normal Courier; ">159 Town Road</font></p>
<p style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-=
left: 0px; ">
<font face=3D"Courier" size=3D"3" style=3D"font: normal normal normal 12px/=
normal Courier; ">Falmouth NS<span class=3D"Apple-converted-space"> <s=
pan class=3D"Apple-converted-space"> </span></span>B0P 1L0</font></p>
<p style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-=
left: 0px; ">
<font face=3D"Courier" size=3D"3" style=3D"font: normal normal normal 12px/=
normal Courier; ">Canada</font></p>
<p style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-=
left: 0px; font: normal normal normal 12px/normal Courier; min-height: 14px=
; ">
<br>
</p>
<p style=3D"margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-=
left: 0px; ">
<font face=3D"Courier" size=3D"3" style=3D"font: normal normal normal 12px/=
normal Courier; ">(902) 472-2322</font></p>
</span></div>
</span></div>
</span></div>
<br>
</div>
</div>
</body>
</html>
--_000_EDE3990F6359409AB7DD4E4AFFE9C321dalca_--
next message in archive
no next message in thread
previous message in archive
previous message in thread
Index of Subjects