A magnetohydrodynamic generator (MHD generator) is a magnetohydrodynamic device that transforms thermal energy and kinetic energy into electricity. MHD generators are different from traditional electric generators because they operate at high temperatures without moving parts. MHD was developed because the hot exhaust gas from an MHD generator can heat the boilers of a steam plant, increasing overall efficiency. MHD was developed as a coverage cycle to increase the efficiency of electric generation, especially when burning coal or natural gas. The MHD dynamos are the complement to the MHD propellers, which have been applied to pump liquid metals and in several experimental engines of the ships.
An MHD generator, like a conventional generator, depends on moving a conductor through a magnetic field to generate electric current. The MHD generator uses hot conductive plasma as the moving conductor. The mechanical dynamo, on the other hand, uses the movement of mechanical devices to achieve this. MHD generators are technically practical for fossil fuels, but have been surpassed by other less expensive technologies, such as combined cycles in which the exhaust of a gas turbine or a fused carbonate fuel cell heats the steam to feed one steam turbine. Natural MHD dynamos are an active area of research in plasma physics and are of great interest to the communities of geophysics and astrophysics, since the magnetic fields of the earth and the sun are produced by these natural dynamos.
History of the MHD Generation
The concept of MHD power generation was first introduced by Michael Faraday in the year 1832 in his Bakerian conference to the Royal Society. In fact, he conducted an experiment on the Waterloo Bridge in Great Britain to measure the current, from the flow of the River Thames into the Earth's magnetic field.
This experiment in a way outlined the basic concept behind the MHD generation over the years then several research papers had been conducted on this topic, and later on August 13, 1940 this concept of magneto hydrodynamic power generation, Was embedded as the most widely accepted for the conversion of thermal energy directly into electrical energy without mechanical subset.
Principle of MHD Generation
The main power generation MHD is very simple and is based on Faraday's law of electromagnetic induction, which states that when a conductor and a magnetic field moves with each other, then the voltage is induced in the conductor, which Results in the current flow through the terminals. As the name implies, the magnetic hydropneumatic dynamics generator shown in the following figure refers to the flow of a conductive fluid in the presence of magnetic and electric fields. In the conventional generator or alternator, the conductor consists of copper coils or strips, whereas in an MHD generator the hot ionized gas or conductive fluid replaces the solid conductor. A pressurized and electrically conductive fluid flows through a transverse magnetic field into a channel or conduit. The electrode pair is located on the channel walls at right angles to the magnetic field and connected through an external circuit to supply power to a load connected to it. The electrodes in the MHD generator perform the same function as the brushes in a conventional DC generator. The MHD generator develops DC power and the conversion to AC is done using an inverter.