Retained Heat (or Fireless) Cookers

Finned Pots as a Means of Increasing Efficiency Dale Andreatta, Ph.D., P.E., dandreatta@sealimited.com, February 13, 2009

Finned Pot

Executive Summary A pot with heat transfer fins has much greater surface area than pots with no fins. In theory, this could lead to greatly increased heat transfer to the pot for a given stove, and the pot would theoretically improve the performance of the stove under all conditions. While we often concentrate on the stove as the primary element of a cooking system, the efficiency of a stove is mainly determined by the heat transfer to the pot, and designing a better pot would be an easy way to make a more efficient stove. A variety of types of finned pots were built and tested. The best designs were separated out in the lab, using natural gas to simulate a wood flame. Several types of fins can be retrofit to existing pots. The better designs of finned pots performed well over a range of conditions using simulated stoves, and sometimes also with an actual wood burning stove modified to use natural gas to simulate a wood flame. With fins on or near the bottom of the pot the finned pots typically gave around a 1.76-fold improvement in heat transfer. If the fins were on the sides of the pot a greater than 2-fold improvement was achieved. Tests on actual stoves using wood as the fuel generally gave smaller improvements in performance, generally 1.33 or less, corresponding to a 25% or smaller reduction in fuel usage. These tests were done under a variety of conditions with a variety of stoves, including the open fire (3-stone fire). On industrial fuel stoves using kerosene or alcohol, improvements were even less, with the finned pots giving 1.2 fold improvements or smaller. In some tests the finned pot used more fuel than an unfinned pot. The reasons for this wide range of results is not known. It is not recommended that finned pots be pursued as a means of increasing the efficiency of stoves. Better results can probably be achieved with less effort by using skirts around the pot. These skirts could be attached to the pots with optimum dimensions. See attached report presented to ETHOS 2009

Anila Biomass Gassifier Stove Designed and built by Professor U.N. Ravikumar (Eng) Mysore University, India In Biochar and SCAD presented by David Friese-Greene, The Schumacher Institute, Bristol (9.88MB pdf)

Anila Stove

Combustion Cycle

The Green Pail Retained Heat Cooker
Lanny Henson, June 7, 2008
Green Pail Cooker

Hay Box/RHC: Cooking in a Basket website
Elizabeth Riddiford,Community Conservation Initiative (CCI-Kenya), June 1, 2007
Kakamenga Basket

Research Report on BACIP Wood Stoves for High Mountain Areas
Designs for Traditional Houses in the Northern Areas, Including Warm Water Facility
BUILDING AND CONSTRUCTION IMPROVEMENT PROGRAMME - BACIP
Aga Khan Planning and Building Services, Pakistan
Sjoerd Nienhuys, BACIP Programme Director, Gilgit, Pakistan, November 2000

BACIP

Foreword

The Building and Construction Improvement Programme (BACIP), operating in the Northern Areas of Pakistan, is a project under the Aga Khan Planning and Building Services, Pakistan (AKPBSP). The programme is financed by PAKSID, a collaboration between the Canadian International Development Aid (CIDA) and the Aga Khan Development Network. The BACIP Programme Director is contracted through the Netherlands International Development Co-operation Programme (DGIS). BACIP works in co-operation with other Aga Khan Development Network Institutions (AKDNI) in the Northern Areas and Chitral, Pakistan. During 1999 and 2000 some 40 staff members, consisting of architects, engineers and social workers, have been involved in the BACIP programme activities. In addition, more than 200 village-based male and female resource persons assist on a voluntary basis in the implementation of the programme.

The present programme (to end-December 2000) consists of the development and introduction of house improvements (more than 40 different types) for traditional and new houses which are useful for villages in remote areas. Technology and skills development among local entrepreneurs has been initiated to enhance the delivery of the house improvements locally. Participatory cluster and village planning is a part of the process as well and community discussions have begun for determining appropriate housing locations to avoid building in geographically hazardous areas. Parallel to these mainstream activities, attention has been given to the design of new schools. As many of the technologies being applied in the new school designs can also be applied in houses, the demonstration effect would have a high impact on the youth and future house builders.

The present report gives an overview of the different types of stoves that have been developed by BACIP. The designs are improvements upon the existing stoves in terms of durability, cost, fuel efficiency and manufacturing techniques. The designs have been repeatedly modified to suit the needs and acceptability of the people.

The BACIP stove (buchari) has been developed on the basis of the AKPBSP (formerly the Aga Khan Housing Board) buchari which was introduced about seven years ago and more than 10,000 installed in the region. The new models have been fitted with various options, such as the top-oven, improved chimney, warm water facility and various chapatti plates for making bread.

See: http://www.bioenergylists.org/stovesdoc/Nienhuys/Stoves-Research-Pakista...