I think that Jim Jetter used a bomb calorimeter in his TLUD tests. Dean
On Sun, Nov 4, 2012 at 2:59 AM, Crispin Pemberton-Pigott < [email protected]> wrote: > Dear Paul > > >What is important is > > the quality of the control of the amount of primary air that can > > enter. VERY WELL DONE. > > The stove is quite airtight on the controllers. > > On another related topic for TLUD's: > > Have you decided on a favourite value for the heat of combustion from the > gases developed from a wood fire in the TLUD's? If you have a wood at 18.4 > MJ/kg dry and you have (say) 20% char left at the end, what would you > consider the heat value per missing kg? Obviously it is not the same as the > initial wood. > > So I wanted to explore this with you. Let's set the moisture at 15% to be > typical of air-dried hot-country fuel wood. > > Starting with an LHV for the dry wood, the net heat LHV is 15.25 MJ/kg. If > there is 200 g of char remaining, and we treat it as being the same as > regular hardwood charcoal, we can assign a heat value of 29.5 * 0.2 = 5.9 > MJ > for the remaining char. > > What remains as heat available is 9.35 MJ. This is from 800 g of missing > fuel so the energy average per missing gram is 9.35/0.8 = 11.69 MK/kg or > 11.69 Joules per gram. > > Do you agree with this approach? > > What it means is that if you put a char-making stove on a scale and run it > you have a value of heat per g missing from the scale. The missing mass is > moisture, wood gas and some of the carbon (about 1/2). > > Using this approach you can determine the net thermal efficiency of the > flame-to-pot+water. As the amount of char remaining is variable and not > known until after the test is completed, it is hard to know what the > performance is during the test but that is a detail. > > You can determine if the thermal efficiency has been improved should you > make changes to the stove body. > > For those who like details, the heat value of the char is usually unknown. > It would have to be homogenised and a sample tested in a bomb calorimeter > to > know what it is exactly. As Penn Taylor pointed out, the value can range > from about 12 to 33 MJ/kg so the real value is going to vary from test to > test. > > Regards > Crispin > > > > _______________________________________________ > Stoves mailing list > > to Send a Message to the list, use the email address > [email protected] > > 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/ > >
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