| Main knowledge bank page |
Recent additions |
Recent changes |
What links here |
Categories |
Category cloud How-to guides | Organisation profiles | Project profiles | |||||||||||||||
Indian Chulha technology since 1983
Improved cookstove (chulha) technology in India has undergone swift changes during the last decade. The improved chulha program, a 'minimum needs programme' of the Government of India, is basically for rural women, and aims to improve their living conditions and create awareness about the saving of big-fuel. It builds on the development work which has taken place in many parts of India over a much larger period. The program, started in December 1983, is supported by 17 Technical Backup Units (TBU), established in various states of the country, for development of appropriate models of improved chulhas, based primarily on studies of actual cooking needs of the region or groups of users. The programme now has more than 40 different types of improved stoves. At the time of launching most of the models used for field propagation had dampers and baffles. [top] [end]Mud stovesThe originally recommended, improved, two-pot, mud stove had a chimney and was fitted with dampers and baffles. Dampers are thin metallic plates, and in a twopot mud stove with chimney the front damper is put across the mouth of the fire-box. It regulates the intake of primary air for the combustion process and controls its cooling effect on the stove. The 'chimney damper' is put across the flue passage between the second pot hole and chimney pipe. It controls the flow of hot gases out through the chimney. The dampers thus play an important role in achieving higher thermal efficiency. As a result of experience, improved chulhas with dampers were rejected by the users for the following reasons:
Failure to use the dampers or incorrect use results in uncontrolled and excessive intake of air and outlet of hot gases due to the 'chimney draught' and so in turn leads to loss of useful heat, and waste of fuel.
However, baffles are easily damaged during the course of repairs by the users. Surveys over the years have revealed that the majority of users are unable to maintain the designed form of the baffle, which becomes ineffective or detrimental to stove performance. The foregoing description of 'improved' chulhas with dampers and baffles indicates how technologies from the laboratory may not work under field conditions. The two components which could enhance thermal efficiency were not accepted by the users for practical reasons. If such improved chulhas were to survive, development of 'darnperless' models became a necessity.
The improved chulha became not only simpler to make but also cheaper. Since 1989, the Government of India, under its National Programme on Improved Chulhas, has approved only damperless models for field propagation. [top] [end]Improved chulhas with ceramic liningsThe important parameters which determine the thermal efficiency of a chimneyless improved chulha are: design dimensions of the firebox, secondary-pot holes and flue passages. Most village stove makers and users are unable to maintain the designed size and shape of these components to the close tolerances needed.The solution to this problem was the use of pottery (ceramic) linings which can be pre-fabricated at the village level and built into the mud stove bodies when installed in the kitchen. These can be carefully designed and accurately made, and are more resistant to wear.
[top] [end]'Unified' models of improved chulhasNew and more appropriate models of improved chulhas were developed to meet regional cooking needs. By 1990, the Government of India had approved more than 40 models for field propagation. A close study of various models indicated that although there were differences in designs to suit local tastes, most of the models had similar working principles.Despite the different cooking needs and habits of rural masses in India, the traditional cooking methods are basically the same. To simplify the choice of most appropriate stove for promotion by field workers and to help production, it was felt necessary to reduce the overall numbers of models. Thus. the concept of a 'Unified' model was created.
[top] [end]Chimneyless chulhasThe chimney, is an important component of an improved chulha as it extracts the products of combustion from the kitchen space and also creates a natural drought in the fire-box to provide the air needed for combustion.
A chimneyless stove needs a completely different design to give optimum combustion and heat transfer, particularly in the combustion chamber and by addition of a grate. Some models have provision for a second pot hole for recovery of exhaust heat. In practise in the field the heat utilization may equal that of a stove with a chimney and smoke emission levels may be within safe limits. Chimneyless stoves are simpler, cheaper and easier to make and use, and so are promoted by the government and the TBUs. Reproduced from GLOW, Vol 18, Dec 1995, a publication of the Asia Regional Cookstove Program [top] [end]Contents: Boiling Point 37: Household energy in emergency situations
| |||||||||||||||
Page created:
15 August 2007; Last edited:
15 August 2007; Version: 0 | |||||||||||||||
Pagename: IndianChulhaTechnologySince1983 @HEDON: APGA | |||||||||||||||
