INTRODUCTION
It is well known that man had always been trying to fined something new to achieve a new aims 80% of total electricity produced in the world is hydral while remaining 20% is produced from nuclear, thermal, solar, Geothermal energy and from magneto hydro dynamic power generation.
MHD power generation is a new system of electric power generation which is said to be of high efficiency and low pollution. In advanced countries MHD generator are widely used but in developing countries like India it is still under construction. This construction work is in progress at Tiruchirapalli in Tamilnadu unders joint efforts of BARC (Bhabha Atomic Research Centre), BHEL, Associated cement corporation and Russian technologists.
As its name implies, magneto-hydro-dynamic (MHD) is concerned with the flow of conducting fluid in presence of magnetic and electric field. This fluid may be gas at elevated temperature or liquid metal like sodium or potassium. A MHD generator is a device for converting heat energy of fuel directly into electric energy without a conventional electric generator. The basic difference between conventional generator and MHD generator is in the nature of conductor.
PRINCIPLE OF MHD POWER GENERATION
The principle of MHD generation is simple, discovered by faraday when an electric conductor moves across a magnetic field, a emf. Is induced in it, which produced an electric current. This is the principle of the conventional generator also, where the conductors consists of copper strips. In MHD generator the solid conductors are replaced by a gaseous conductor; i.e. an ionized gas. If such gas is passed at high velocity through a powerful magnetic field, i.e. suppose we have a charged particle (having charge q) moving at a high velocity ‘V’ towards right and a perpendicular magnetic field is applied. A magnetic force ‘F’ acts on the charged particle. Show in fig. A Positively charged particles as forced upward and negatively charged particle is forced downward.
The positive ions would be accelerated towards the upper plate P, and negative ions would be accelerated towards the plate P2 . If the P1 and P2 are externally connected through a resistance, a current would flow through the resistance. Thus gas energy directly converted into electrical energy. This is the principle of MHD generator. A MHD conversion is known as direct energy conversion because it produced electricity directly from heat source without the necessity of the additional stage of steam generation as in a steam power plant.