A Sound-powered Wood Stove for Cooking, Refrigeration, and Electricity
Introduction
Cooking food over open fires has been a source of several problems in developing countries such as Asia and Africa. An open fire stove not only act as a source of air pollution, but also leads to adverse health conditions in the people using it. Open stoves are still used extensively by the people in developing countries as an important domestic appliance.
In order to eradicate the problem related to open stoves, a Stove for Cooking, Refrigeration, and Electricity or SCORE technology has been implemented in several developing countries. The thermo-acoustics technology as it is called converts heat from any heating medium into sound waves that can be used for cooking, refrigerating, or for generating electricity.
Working
Generally, all open stoves used by the people in developing countries have wood as the main source of heat. Wood is the most inefficient source of fuel when burnt; ninety-three percent of its energy goes up in the smoke.
However in the SCORE system, wood is place inside a stove-like chamber that is attached to a chimney. The wood when burnt heats up compressed air which is then pumped into the chamber via a special arrangement of pipes. As the compressed air heats up inside the sealed chamber, it starts vibrating and produces sound waves. The hot air is then passed through a set of pipes that leads towards the stove’s hob. It is said that the sound of vibration generated inside the compressed chamber is hundred times the sound of a jet taking off. However, the pipes are built so strong that they do not vibrate and can take all the stress.
The generated sound waves then vibrate a diaphragm that is located at the end of the pipes. On the other side, the diaphragm is attached to a metal wire coil that is surrounded by magnets. Now, as the diaphragm vibrates, the metal wire coil also vibrates inside a magnetic field, producing around fifty vibrations per second. This vibration motion inside the magnetic field generates electricity which is taken off and converted into required voltage. The generated electricity can be used to cook food and to provide energy to various domestic appliances through an electrical socket provided in the system’s body, where the appliances can be plugged in.
In order to use SCORE as a refrigeration appliance, the compressed air is taken though pipes to a separate chamber. The sound waves expand the air in the chamber and thus cool down the temperature to provide the required refrigeration. In around two hours of working, SCORE can produce enough power to keep a fridge cold for twenty four hours.
Moreover, the smoke generated by burning the wood is taken away from the user through a chimney and released in the air, preventing it from entering user’s body. As most of the energy of the burned wood is used in generating sound waves, the amount of smoke produced is also less.
Thus, SCORE is an amazing medium for improving the lifestyle of millions of people in many developing countries by providing them not only an affordable appliance for their domestic activities but also a means for protecting their health.
Application
SCORE is a two-million pound project mainly concentrating on the needs of rural people in Africa and Asia. Each of these stoves would weigh around ten to twenty kilograms and can use fuels such as biomass, coal, wood etc. The SCORE stoves are known as “Biomass” stoves in India and have been in great demand since their launch. Envirofit, the company providing the stoves to India, has already sold fifteen thousand pieces since its launch in May of this year. The stoves will also be launched in developed countries in a modified way so as to cater to the domestic needs of urban people in an environment friendly way.
