Combustion

The C-H-O Fuel Map
Thomas Reed, Biomass Energy Foundation, October 4, 2007

Stove Performance Report: Mayon Rice Hull Stove
Aprovecho research Center, July 18, 2005

INTRODUCTION:

This report serves to provide detailed performance measures of the smaller red model of the Mayon Turbo Rice Hull cooking stove including speed, fuel use, efficiency, and emissions produced. Stove performance is also considered in comparison to a laboratory open fire and the average of four similar wood burning stoves recently tested at the Aprovecho laboratory. Comments are included describing ease of use and recommendations for possible design improvement.

The Mayon Turbo stove reduces both Carbon Monoxide and Particulate Matter when compared to a carefully operated open fire. It is especially successful at reducing Particulate Matter.

RESULTS AT A GLANCE:

Dry Fuel Equivalent Calculator
Crispin and Nigel Pemberton-Pigott, October 2007

Dear Stoves Testers

See the attached Dry Fuel Equivalent Calculator drawn up for evaluation by our list readers.

There are 4 pages to the spreadsheet. The first is where a test result can be entered. If you only know the mass of damp fuel burned, the amount of charcoal remaining and the moisture content of the fuel, it should be sufficient.

Select a suitable dry fuel heat content from the chart on the right if you don’t know the figure exactly.

The first set of numbers is the actual heat value of the fuel that was offered to the pot. The second sheet is the heat value as calculated by the UCB-WBT method. The Dry Wood Equivalent figure in the UCB-WBT is not used (as previously discussed), but a different formula which can be seen in their spreadsheet by clicking on the cell.

The difference between the two output figures is calculated on the third page.

The fourth page is the two methods plotted in two different manners, the actual value of dry fuel equivalent against the UCB-WTB for a range of moisture and charcoal remaining, both as a % of wet fuel burned, then the relative value of the outputs.

You will notice, playing with the numbers, that when the heat value of the fuel is more than about 20 MJ/Kg the dry fuel equivalent has been under-reported by the UCB-WBT. Conversely, when the actual heat in the fuel is less than 20, that method over-reports the heat yielded giving the impression that the stove has not performed as well as it actually did. In the case of a fuel like rice hulls, the difference is significant. Note that the charcoal heat content should be changed for the rice hulls – see the small chart on the right of page 1.

As always, please look for errors in the calculations. Sorry about the formatting of the graphs – the cells with no or very high plus or minus values get plotted as zero, mostly in order to make the lower moisture calculations more readable.

Best regards
Crispin and Nigel Pemberton-Pigott
Waterloo
Ontario

A Report on Some Experiments with the Top-Lit Up Draft (TLUD) Stove 500k pdf
Dale Andreatta, dandreatta@sealimited.com, ETHOS January 27, 2007

Burning of wood

Rocket Stove Questions and Answers: Rocket Stove Air Supply - Primary and Secondary Air
Hugh Burnham-Slipper (UK) and Kevin Chisholm (CAN), Dean Still (Aprovecho), AD Karve (ARTI, India) November 25-26, 2006

Rocket Design (Aprovecho)

Select to Enlarge

Q.
Dear Stovers,
The fuel magazine that sticks out the side of a rocket stove is divided into two: above the shelf is where the fuel goes, and air passes under the shelf. Am I right in thinking that the fuel should be packed in as much as possible, to try and minimise the amount of air entering the stove through the fuel inlet? If so, why? My experience is that char builds up at the bottom of the elbow, so air is needed to burn the char (which in turn pyrolises the fuel), and a second air supply is required to burn the volatile gases. Any pointers would be warmly received.
Confused, Hugh.

The Fuel Composition-Conversion Diagram (pdf)
The Equivalence Ratio: The Key to Understanding Pyrolysis, Combustion and Gasification of fuels (pdf)

Basics on Combustion: Concepts and Calculations
Kanchan Rai, Nepal July 2004