| Boiling Point No. 05 - September 1983 |
A Mandal and Dr Rajendra Prasad Indian Institute of Technology, New Delhi
The following is taken from an article titled 'An Efficient Smokeless Wood Burning Stove'.
Efforts to improve the traditional methods of cooking over open fires began, in India, about a quarter of a century ago.
In 1953, Hyderabad Engineering Research Laboratories (HERL) designed a chulah which was a major improvement. This chulah is claimed to be extensively used and to save 40% of firewood compared to an open fire.
The Magan Chulah was developed in 1947 at Maganwadi, Wardha. The design accommodated the pot seats on the stove top so that their centres formed an equivalent triangle and utilised an indirect fire channel to the chimney.
In collaboration with the Research and Action Institute, Lucknow, NBO improved the Junagarh chulah whose efficency was reported as 24-72%.
The U P Water Development Corporation modified the Junagarh Chulah and though the height was found to be too low, several chulahs installed in a village worked satisfactorily.
The Gujrat chulah is a modified version of the HERL chulah. The Mada chulah design is based on the Lorena stove from Guatemala, and is being propagated in villages near Chandigarh under a Ford Foundation scheme.
Other smokeless stoves developed or being introduced in India are the Ghana, the New Nepali, and the Kathmandu chulahs.
Based on the results of these chulahs, and on experiments on open fires, a new chulah has been designed and tested at I I T. (Fig 1). The outer appearance is similar to the chulah developed at Jai Nigam, UP, though the dimensions are different and selected on the basis of experiments carried out at II T. It is a two pot chula and is made using moulds. Moulds have been introduced for constructing the firebox as well as the second pot-hole, and small pieces of cement pipes are used for providing the flue tunnels between the firebox and second pot-hole as well as between the pot-hole and chimney. At this moment wooden moulds are used, but several other materials can be tried. The moulds are shown in Fig 2. The chulah has a cement pipe chimney of 7.5 cm diameter with a smoke vent at the top. Between the second pot-hole and the chimney a heat controlling device - a cement damper - is provided to control the flue gases.
Another damper is provided in front of the fire box to control air inlet. The burning rate of fuel can be affected by suitable adjustment of the dampers. With the proper use of dampers more heat is available. The efficiency obtained is about 24%.
A major break through is the extremely simple technique of construction, which can be done to the exact dimensions required with no special skills or training needed.
This new chulah has been constructed in more than 15 houses in a labour colony near I I T. The chulah is highly acceptable to the poor people. They can clearly see a saving in their fuel. The new chulah gives an additional pot seat to cook on and at the same time saves the cook from smoke.