[Stoves] radiant heat capture, total heat measurement

[Tom Miles]

Alex, Paul,

One option is to use a suction pyrometer in which you pull the hot gas past
the thermocouple in a tube. The tube limits the radiation so you get a
better picture of the true temperature. Temperatures can be about 90C (200F)
higher in the suction pyrometer than in a boiler or free air. A simple
version can be made with compressed air venture drawing air through a pipe
with a thermocouple inside it.  

Tom  

-----Original Message-----
From: stoves-bounces at lists.bioenergylists.org
[mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Alex English
Sent: Wednesday, March 14, 2012 6:18 PM
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] radiant heat capture, total heat measurement

Paul,
So this makes sense. The screen radiates away heat leaving a cooler gas
beyond.
If your thermocouple were smaller or shielded the difference would likely be
even greater because the thermocouple looses  more heat from radiation when
it is hotter.

Or are there other reasons, too?
Alex



On 14/03/2012 7:36 PM, Paul Olivier wrote:
> There are problems with what I have written below.
> Let me again.
>
> Without the dome, the probe encounters hot gases and registers a 
> temperature of 563 C.
> It turns red hot and starts emitting thermal radiation.
>
> With the dome, the probe encounter hot gases as well as thermal radiation.
> But it only registers a temperature of 500 C.
> It does not turn red hot.
> Therefore the probe does not absorb thermal radiation from the dome 
> very well.
>
> Thanks.
> Paul
>


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