MAGNETO HYDRO DYNAMICS

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MAGNETO HYDRO DYNAMIC POWER GENERATION (MHD ):

MAGNETO HYDRO DYNAMIC POWER GENERATION (MHD ) PREPARED BY: MANINDER PABLA

CONTENTS:

CONTENTS INTRODUCTION PRINCIPLE VARIOUS SYSTEMS ADVANTAGES DISADVANTAGES APLLICATIONS NEED FOR FURTHER RESEARCH FUTURE PROSPECTS CONCULSION

INTRODUCTION:

INTRODUCTION Magneto hydrodynamics (MHD) (magneto fluid dynamics or hydro magnetics ) is the academic discipline which studies the dynamics of electrically conducting fluids. Examples of such fluids include plasmas, liquid metals, and salt water. The word magneto hydro dynamics (MHD) is derived from magneto- meaning magnetic field, and hydro- meaning liquid, and -dynamics meaning movement. The field of MHD was initiated by HANNES ALFVEN , for which he received the Nobel Prize in Physics in 1970

INTRODUCTION:

INTRODUCTION 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 generators are widely used but in developing countries like INDIA, it is still under construction, this construction work in in progress at TRICHI in TAMIL NADU, under the joint efforts of BARC (Bhabha atomic research center), Associated cement corporation (ACC) and Russian technologists. As its name implies, magneto hydro dynamics (MHD) is concerned with the flow of a conducting fluid in the presence of magnetic and electric field. The fluid may be gas at elevated temperatures or liquid metals like sodium or potassium.

INTRODUCTION:

INTRODUCTION An MHD generator is a device for converting heat energy of a fuel directly into electrical energy without conventional electric generator. In this system. An MHD converter system is a heat engine in which heat taken up at a higher temperature is partly converted into useful work and the remainder is rejected at a temperature. Like all heat engines, the thermal efficiency of an MHD converter is increased by supplying the heat at the highest practical temperature and rejecting it at the lowest practical temperature.

PRINCIPLES OF MHD POWER GENERATION:

PRINCIPLES OF MHD POWER GENERATION

PRINCIPLES OF MHD GENERATION:

PRINCIPLES OF MHD GENERATION The Lorentz Force Law describes the effects of a charged particle moving in a constant magnetic field. The simplest form of this law is given by the vector equation. where F is the force acting on the particle. Q is the charge of the particle, v is the velocity of the particle, and B is the magnetic field. The vector F is perpendicular to both v and B according to the right hand rule.

PRINCIPLES OF MHD POWER GENERATION:

PRINCIPLES OF MHD POWER GENERATION The electro magnetic induction principle is not limited to solid conductors. The movement of a conducting fluid through a magnetic field can also generate electrical energy. When a fluid is used for the energy conversion technique, it is called MAGNETO HYDRO DYNAMIC (MHD), energy conversion. The flow direction is right angles to the magnetic fields direction. An electromotive force (or electric voltage) is induced in the direction at right angles to both flow and field directions, as shown in the next slide.

VARIOUS MHD SYSTEMS:

VARIOUS MHD SYSTEMS The MHD systems are broadly classified into two types. OPEN CYCLE SYSTEM CLOSED CYCLE SYSTEM Seeded inert gas system Liquid metal system

OPEN CYCLE MHD SYSTEM:

OPEN CYCLE MHD SYSTEM

OPEN CYCLE SYSTEM:

OPEN CYCLE SYSTEM The fuel used maybe oil through an oil tank or gasified coal through a coal gasification plant The fuel (coal, oil or natural gas) is burnt in the combustor or combustion chamber. The hot gases from combustor is then seeded with a small amount of ionized alkali metal (cesium or potassium) to increase the electrical conductivity of the gas. The seed material, generally potassium carbonate is injected into the combustion chamber, the potassium is then ionized by the hot combustion gases at temperature of roughly 2300’ c to 2700’c.

OPEN CYCLE SYSTEM:

OPEN CYCLE SYSTEM To attain such high temperatures, the compressed air is used to burn the coal in the combustion chamber, must be adequate to at least 1100’c. A lower preheat temperature would be adequate if the air is enriched in oxygen. An alternative is used to compress oxygen alone for combustion of fuel, little or no preheating is then required. The additional cost of oxygen might be balanced by saving on the preheater. The hot pressurized working fluid living in the combustor flows through a convergent divergent nozzle. In passing through the nozzle, the random motion energy of the molecules in the hot gas is largely converted into directed, mass of energy. Thus , the gas emerges from the nozzle and enters the MHD generator unit at a high velocity.

OPEN CYCLE SYSTEM:

OPEN CYCLE SYSTEM The MHD generator is a divergent channel made of a heat resistant alloy with external water cooling. The hot gas expands through the rocket like generator surrounded by powerful magnet. During motion of the gas the + ve and – ve ions move to the electrodes and constitute an electric current. The arrangement of the electrode connection is determined by the need to reduce the losses arising from the Hall effect. By this effect, the magnetic field acts on the MHD-generated current and produces a voltage in flow direction of the working fluid.

CLOSED CYCLE SYSTEM:

CLOSED CYCLE SYSTEM Two general types of closed cycle MHD generators are being investigated. Electrical conductivity is maintained in the working fluid by ionization of a seeded material, as in open cycle system. A liquid metal provides the conductivity. The carrier is usually a chemical inert gas, all through a liquid carrier is been used with a liquid metal conductor. The working fluid is circulated in a closed loop and is heated by the combustion gases using a heat exchanger. Hence the heat sources and the working fluid are independent. The working fluid is helium or argon with cesium seeding.

CLOSED CYCLE SYSTEM:

CLOSED CYCLE SYSTEM

ADVANTAGES:

ADVANTAGES The conversion efficiency of a MHD system can be around 50% much higher compared to the most efficient steam plants. Still higher efficiencies are expected in future, around 60 – 65 %, with the improvements in experience and technology. Large amount of power is generated. It has no moving parts, so more reliable. The closed cycle system produces power, free of pollution. It has ability to reach the full power level as soon as started.

DISADVANTAGES:

DISADVANTAGES Suffers from reverse flow (short circuits) of electrons through the conducting fluids around the ends of the magnetic field. Needs very large magnets and this is a major expense. High friction and heat transfer losses. High operating temperature. Coal used as fuel poses problem of molten ash which may short circuit the electrodes. Hence, oil or natural gas are much better fuels for MHDs. Restriction on use of fuel makes the operation more expensive.

APPLICATIONS:

APPLICATIONS Power generation in space craft. Hypersonic wind tunnel experiments. Defense application.

NEED FOR FURTHER RESEARCH :

NEED FOR FURTHER RESEARCH The MHD channel operates on extreme conditions of temperature, magnetic and electric fields . So, numerous technological advancements are needed prior to commercialization of MHD systems . Search is on for better insulator and electrode materials which can with stand the electrical, thermal, mechanical and thermo-chemical stresses and corrosion .

CONCLUSION :

CONCLUSION The MHD power generation is in advanced stage today and closer to commercial utilization. Significant progress has been made in development of all critical components and sub system technologies. Coal burning MHD combined steam power plant promises significant economic and environmental advantages compared to other coal burning power generation technologies. It will not be long before the technological problem of MHD systems will be overcame and MHD system would transform itself from non- conventional to conventional energy sources.

FUTURE PROSPECTS:

FUTURE PROSPECTS It is estimated that by 2020, almost 70 % of the total electricity generated in the world will be from MHD generators. Research and development is widely being done on MHD by different countries of the world. Nations involved: USA Former USSR Japan India China Yugoslavia Australia Italy Poland

Thank you….. :

Thank you…..

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