[Stoves] radiant heat capture, total heat measurement

Ronald Hongsermeier rwhongser at web.de
Thu Mar 8 12:57:08 CST 2012 

Hi Frank,

I found the following article to be helpful:

http://en.wikipedia.org/wiki/Heat_transfer

additionally, the following list of subjects is found in the wikipedia 
article on Material_properties under the subheading "Thermal 
properties". I think several of these are of interest to pyroloytic 
science from a wide variety of angles: fuels, air, stove/burner 
materials, etc.

  * Autoignition temperature
    <http://en.wikipedia.org/wiki/Autoignition_temperature>
  * Binary phase diagram <http://en.wikipedia.org/wiki/Binary_phase_diagram>
  * Boiling point <http://en.wikipedia.org/wiki/Boiling_point>
  * Coefficient of thermal expansion
    <http://en.wikipedia.org/wiki/Coefficient_of_thermal_expansion>
  * Critical temperature <http://en.wikipedia.org/wiki/Critical_temperature>
  * Curie point <http://en.wikipedia.org/wiki/Curie_point>
  * Emissivity <http://en.wikipedia.org/wiki/Emissivity>
  * Eutectic point <http://en.wikipedia.org/wiki/Eutectic_point>
  * Flammability <http://en.wikipedia.org/wiki/Flammability>
  * Flash point <http://en.wikipedia.org/wiki/Flash_point>
  * Glass transition temperature
    <http://en.wikipedia.org/wiki/Glass_transition_temperature>
  * Heat of fusion <http://en.wikipedia.org/wiki/Heat_of_fusion>
  * Heat of vaporization <http://en.wikipedia.org/wiki/Heat_of_vaporization>
  * Inversion temperature
    <http://en.wikipedia.org/wiki/Inversion_temperature>
  * Melting point <http://en.wikipedia.org/wiki/Melting_point>
  * Phase diagram <http://en.wikipedia.org/wiki/Phase_diagram>
  * Pyrophoricity <http://en.wikipedia.org/wiki/Pyrophoricity>
  * Solidus <http://en.wikipedia.org/wiki/Solidus>
  * Specific heat <http://en.wikipedia.org/wiki/Specific_heat>
  * Thermal conductivity <http://en.wikipedia.org/wiki/Thermal_conductivity>
  * Thermal diffusivity <http://en.wikipedia.org/wiki/Thermal_diffusivity>
  * Thermal expansion <http://en.wikipedia.org/wiki/Thermal_expansion>
  * Seebeck coefficient <http://en.wikipedia.org/wiki/Thermopower>
  * Triple point <http://en.wikipedia.org/wiki/Triple_point>
  * Vapor Pressure <http://en.wikipedia.org/wiki/Vapor_Pressure>
  * Vicat softening point
    <http://en.wikipedia.org/wiki/Vicat_softening_point>

hth,
regards,
ron von und zu porzellanbehütung   :/

On 08.03.2012 19:30, Frank Shields wrote:
> Dear Kevin Crispin and all,
>
> So you can heat an object 'around a corner' using a mirror at 45 deg. C - if
> I understand what you are saying. You can focus heat to an object (pot)
> using light colored materials directed at an angle to do that.  Great
> experiment!
>
> Another question if you don't mind.
> Heating an iron block  cm X cm X cm in a furnace to 400 deg C and picking it
> up and placing in a liter of water at room temperature and measuring
> temperature increase of the water will give the amount of heat that
> centimeter block will hold. And can calculate the amount of wood needed to
> heat a stove body of, say 500kg (realizing heat leaves at a certain rate).
> Is there a word and  list of values for different materials of the amount of
> heat a material will hold (or required) for different temperatures? Seems
> this an important thing to know because it is the minimum biomass (joules)
> needed to bring the stove body to a temperature where the fuel will be clean
> burning.  The material type, weight and heat holding value should be a part
> of stove 'value' when comparing one to another as it's the startup and cool
> down that gives the dirtiest air.
>
> Thanks
> Frank
> Frank Shields
> 42 Hangar Way
> Watsonville,  CA  95076
> (831) 724-5244 tel
> (831) 724-3188 fax
> frank at bioCharlab.com
>
>
> PS  Kevin - see any Northern Lights last night?
>
>
>
>
>
> -----Original Message-----
> From: stoves-bounces at lists.bioenergylists.org
> [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Kevin
> Sent: Wednesday, March 07, 2012 8:32 PM
> To: Discussion of biomass cooking stoves
> Subject: Re: [Stoves] radiant heat capture, total heat measurement
>
> Dear Frank
>
> OK... basically, a surface radiates or absorbs energy as a function of its
> emissivity. A "Black Body" is such a perfect radiation and absorption
> surface. It has an Emissivity of 1.00 Good "real world absorbers" have an
> emissivity in the range of about .9 to .95, while "poor real world
> absorbers" have an emissivity in the range of about .02 to .05. These Poor
> absorbers" are thus "excellent reflectors."
>
> With this as an "opener", see further comments within your text below....
>
> ----- Original Message -----
> From: "Frank Shields"<frank at compostlab.com>
> To: "'Discussion of biomass cooking stoves'"
> <stoves at lists.bioenergylists.org>
> Sent: Wednesday, March 07, 2012 8:30 PM
> Subject: Re: [Stoves] radiant heat capture, total heat measurement
>
>
>> Dear Kevin
>>
>> That is what I was wondering. But that is then a 'new' heat source(?).
>> Correct?
> # No, it is not a "new" heat source. The mirror, perhaps having an
> emissivity of .05 would simply reflect .95 of teh radiant energy landing on
> it.
>
>   That shinny surface must be hotter than the next surface being.
>
> # It would be marginally hotter than its immediate surroundings, in that it
> reflected only 95% of teh radiant energy that fell on it.  the heat is NOT
> so much a source of "radiant heat", but rather "reflected radiant heat."
>
>> heated up by the radiant heat it then gives off. OR can you reflect heat
>> to
>> another surface without heating the surface doing the reflecting?
> # Yes, if you had a surface with 0.0 Emissivity... you would have a 100%
> efficient reflector, with no energy absorption.
>
>   Then when
>> measuring that shinny surface using an IR gun it reads low heat but the
>> surface it reflecting too will read higher heat? Is that possible?
>>
> # I did an interesting experiment as follows:
> I have a flat mirror on a wall. I have a cheap "Laser Thermometer", which
> when pointed to the wall beside the mirror reads
> : 45 degree angle: 55 F
>   90 degree angle 55 F
>
> # When pointed at teh mirror,
> 45 degree angle 55 F
> 90 degree angle 56 F
>
> #When pointed at my hand, I read 92 degrees F
> When pointed to the mirror, but with the reflected red dot hitting my hand,
> I read 60 F
> When I remove my hand from the path of teh reflected beam and the red dot
> hits teh wall, I read 57
>
> # I conclude that:
> 1: This cheap "Laser Thermometer is actually very good.
> 2: It appears to correct for the different emissivities of a mirrored
> surface, e=.05, and a wall, e=.9
> 3: It measures the surface temperature of the mirror, and not the
> temperature of teh reflected surface.
> 4: However, while it "mostly measures the mirror surface, the "reflected
> measurement" of my hand temperature was a bit above room temperature.
>
> # Perhaps others will have a different interpertation of my little test?
>
> Best wishes,
>
> Kevin
>
>
>
>> Thanks
>>
>> Frank
>>
>>
>>
>> -----Original Message-----
>> From: stoves-bounces at lists.bioenergylists.org
>> [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Kevin
>> Sent: Wednesday, March 07, 2012 1:54 PM
>> To: Discussion of biomass cooking stoves
>> Subject: Re: [Stoves] radiant heat capture, total heat measurement
>>
>> Dear Frank
>> ----- Original Message -----
>> From: "Frank Shields"<frank at compostlab.com>
>> To: "'Discussion of biomass cooking stoves'"
>> <stoves at lists.bioenergylists.org>
>> Sent: Wednesday, March 07, 2012 5:30 PM
>> Subject: Re: [Stoves] radiant heat capture, total heat measurement
>>
>>
>>> Stovers,
>>>
>>> Quick question - does radiant heat require the subject be 'n sight' of
>>> the
>>> object being heated?
>> "Radiant Heat" is basically the same as "conventional light", in that it
>> goes in straight lines, but can be reflected. A "low emissivity" surface,
>> such as polished silver, will reflect "radiant heat" to areas that cannot
>> "see teh source" directly. (Same as a mirror will reflect light "around
>> corners.")
>>
>> Best wishes,
>>
>> Kevin
>>> Thanks
>>>
>>> Frank
>>>
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: stoves-bounces at lists.bioenergylists.org
>>> [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Richard
>>> Stanley
>>> Sent: Wednesday, March 07, 2012 12:27 PM
>>> To: Discussion of biomass cooking stoves
>>> Subject: Re: [Stoves] radient heat capture, total heat measurement
>>>
>>> Andrew,
>>> Its the old quandry of  Brownian movement then, eh ?
>>>
>>> Still that "sense we an animals all have of "heat' and "warmth "
>>> remains well beyond degrees of temperature oer se.
>>> Something missing between science and perception that unless clarified
>>> and
>>> quantified would seem to leaves stove performance assessment abit untidy.
>>>
>>> Richard Stanley
>>> www.legacyfound.org
>>> =======
>>>
>>> On Mar 7, 2012, at 11:44 AM, ajheggie at gmail.com wrote:
>>>
>>> On Tue, 6 Mar 2012 07:47:03 -0800, Richard Stanley wrote:
>>>
>>>> If radient energy is the mother and conductive convective "heats" are
>>> added expressions of it,  then why does one rely only upon measurement of
>>> thermal heat only in these more tangible but not necessarily more
>>> influential bands of the spectrum,  as the standard  measure of cooking
>>> efficiency ?
>>>
>>> I suppose it's to do with what means we have of producing the power to do
>>> the cooking, fire is the easiest way of liberating the energy and
>>> transferring it to the cooking pot. Plants have concentrated sunlight
>>> into
>>> wood.
>>>
>>> Light can plainly be used for heating, didn't one of the ancient greeks
>>> write of the concentrated beams reflected from polished bronze shield
>>> setting fire to ships rigging?
>>>
>>>> Micro waves in themselves are not "hot" but they do a wonderful job of
>>> heating by disturbing molecules, just as the visible band of radiation we
>>> call heat, does.
>>>
>>> Presumably there was no evolutionary advantage in having an organ that
>>> can
>>> sense infra red in the same way eyes interpret light but many animals do
>>> have increased sense of warmth, snakes can hunt by it.
>>>
>>> Microwaves for cooking have only become commonplace in the last 60 years
>>> but the principle is the same as other means of heating, they selectively
>>> excite water molecules. The microwave radiation is tuned to deliver in
>>> frequencies which water molecules will accept in discrete amounts,
>>> otherwise
>>> they would just pass straight through.
>>>
>>>> My naked supposition is therefore, that beyond a normal thermometer or
>>>> one
>>> measuring just IR, one needs a more comprehensive "molecule disturbing"
>>>> measurment device
>>> A thermometer is something that reacts to change in temperature, it
>>> doesn't
>>> measure the activity of molecules but rather compares the effect the
>>> molecules have on a substance.
>>>
>>> I don't think it is possible to directly measure the state of a molecule
>>> without changing it.
>>>
>>> AJH
>>>
>>> _______________________________________________
>>> Stoves mailing list
>>>
>>> to Send a Message to the list, use the email address
>>> stoves at lists.bioenergylists.org
>>>
>>> to UNSUBSCRIBE or Change your List Settings use the web page
>>>
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists
>>> .org
>>>
>>> for more Biomass Cooking Stoves,  News and Information see our web site:
>>> http://www.bioenergylists.org/
>>>
>>>
>>>
>>> _______________________________________________
>>> Stoves mailing list
>>>
>>> to Send a Message to the list, use the email address
>>> stoves at lists.bioenergylists.org
>>>
>>> to UNSUBSCRIBE or Change your List Settings use the web page
>>>
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists
>>> .org
>>>
>>> for more Biomass Cooking Stoves,  News and Information see our web site:
>>> http://www.bioenergylists.org/
>>>
>>>
>>>
>>> _______________________________________________
>>> Stoves mailing list
>>>
>>> to Send a Message to the list, use the email address
>>> stoves at lists.bioenergylists.org
>>>
>>> to UNSUBSCRIBE or Change your List Settings use the web page
>>>
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists
>> .org
>>> for more Biomass Cooking Stoves,  News and Information see our web site:
>>> http://www.bioenergylists.org/
>>>
>>>
>>>
>>> -----
>>> No virus found in this message.
>>> Checked by AVG - www.avg.com
>>> Version: 2012.0.1913 / Virus Database: 2114/4856 - Release Date: 03/07/12
>>>
>>
>> _______________________________________________
>> Stoves mailing list
>>
>> to Send a Message to the list, use the email address
>> stoves at lists.bioenergylists.org
>>
>> to UNSUBSCRIBE or Change your List Settings use the web page
>>
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists
>> .org
>>
>> for more Biomass Cooking Stoves,  News and Information see our web site:
>> http://www.bioenergylists.org/
>>
>>
>>
>> _______________________________________________
>> Stoves mailing list
>>
>> to Send a Message to the list, use the email address
>> stoves at lists.bioenergylists.org
>>
>> to UNSUBSCRIBE or Change your List Settings use the web page
>>
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists
> .org
>> for more Biomass Cooking Stoves,  News and Information see our web site:
>> http://www.bioenergylists.org/
>>
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 2012.0.1913 / Virus Database: 2114/4856 - Release Date: 03/07/12
>>
>
> _______________________________________________
> Stoves mailing list
>
> to Send a Message to the list, use the email address
> stoves at lists.bioenergylists.org
>
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists
> .org
>
> for more Biomass Cooking Stoves,  News and Information see our web site:
> http://www.bioenergylists.org/
>
>
>
> _______________________________________________
> Stoves mailing list
>
> to Send a Message to the list, use the email address
> stoves at lists.bioenergylists.org
>
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org
>
> for more Biomass Cooking Stoves,  News and Information see our web site:
> http://www.bioenergylists.org/
>
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 10.0.1424 / Virus Database: 2113/4858 - Release Date: 03/08/12
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20120308/469bc582/attachment.html>

More information about the Stoves mailing list