MAGNETO HYDRO DYNAMIC POWER GENERATIONA seminar reportSubmitted in partial fulfillment of the requirements for the award of degreeof

BACHELOR OF TECHNOLOGYinELECTRICAL AND ELECTRONICS ENGINEERINGbyM Sai Vaishnav (12071A0228)ELECTRICAL & ELECTRONICS ENGINEERING DEPARTMENT

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERINGVNR Vignana Jyothi Institute of Engineering & TechnologyBachupally, Nizampet (S.O)Hyderabad-500090

VNR Vignana Jyothi Institute of Engineering & TechnologyBachupally, Nizampet (S.O),Hyderabad-500090 DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING CERTIFICATE This is Certified that the Mangneto Hydro Power Generation which is a study topic done by M Sai Vaishnav (12071A0228) in partial fulfillment for the award of the degree of Bachelor of Technology in the Department of Electrical & Electronics Engineering, during the year 2015-2016. The Seminar has been approved as it satisfies the academic requirements. Seminar Co-ordinators HOD-EEE 1. Dr. J. Bhavani Dr. K. Anuradha 2. Mrs. M. Nagajyothi

ABSTRACT

The demand for electricity is increasing at alarming rate and the demand for power is running ahead of supply. The present day methods of power generation are not much efficient & it may not be sufficient or suitable to keep pace with ever increasing demand. The recent severe energy crisis has forced the world to rethink & develop the Magneto Hydro Dynamic (MHD) type power generation which remained unthinkable for several years after its discovery. It is a unique & highly efficient method of power generation with nearly zero pollution. It is the generation of electric power directly from thermal energy utilizing the high temperature conducting plasma moving through an intense magnetic field. In advanced countries this technique is already in use but in developing countries its still under construction. Efficiency matters the most for establishing a power plant. MHD power plants have an overall efficiency of 55-60% but it can be boosted up to 80% or more by using superconducting magnets in this process. Whereas the other non-conventional methods of power generation such as solar, wind, geo-thermal, tidal have a highest efficiency not more than 35%. Hence by using MHD power generation method separately or by combined operation with thermal or nuclear plants we hope to bring down the energy crisis at a high rate.

1. INTRODUCTION We all are aware of power generation using hydel, thermal and nuclear resources. In all the systems, the potential energy or thermal energy is first converted in to mechanical energy and then the mechanical energy is converted in to electrical energy. The conversion of potential energy in to mechanical energy is considerably high (70 to 80%) but conversion of thermal energy in to mechanical energy is considerably poor (40 to 45%). In addition to this the mechanical components required for converting heat energy in to mechanical energy are large in number and considerably costly. This requires huge capital cost as well as maintenance cost also. The scientists are thinking to eliminate the mechanical system and convert thermal in to direct electrical energy for the last 50years and more. Unfortunately, no system is yet developed in large capacity (MW) to compete with conventional systems. In addition to this the efficiency of such conversion remained considerably poor(less than10%) therefore , these power generating systems are not developed on large scale. 1.1 Thermodynamic energy conversion The electricity generation process, most often, is characterized by the transition of primary or secondary energy, from thermal to mechanical and then to electricity. The production of electricity, through conventional forms or commercial of primary energy, concern only the hydroelectric and thermal power station. ). In the hydroelectric power generation, mechanical energy, in different forms (kinetic, potential and pressure) from flowing fluid, is converted into electricity with a water turbine and an alternator. The thermal power stations use some primary source (usually fossil fuels such as natural gas, oil, coal, etc., wood and biomass, municipal or industrial solid waste, nuclear fuels and more rarely geothermal energy). In the thermal power plants the thermal energy is converted into mechanical energy and from this machine the mechanical energy into electricity. It should be noted that in any conversion process one cannot fully convert the energy from one form to another, each of the steps being characterized by a conversion efficiency, a coefficient that takes into account the fraction of the energy initially available, which is converted in the desired form.

1.2 Direct Energy ConversionThe possibilities of improving significantly the conventional energy conversion processes are mainly related to technological progress. They still have small margins and for this reason the researchers have turned to the development of other systems, so called no-conventional. In the conventional conversion systems a significant loss of energy occurs in the transition from thermal to mechanical energy (thermodynamic conversion). Research is focusing its efforts on conversion processes that do not use this step. The absence of moving mechanical parts may allow the achievement of operating temperatures much higher than those typical of conventional processes, resulting therefore, at least potentially, a higher conversion efficiency. These processes are known as direct conversion, as primary and secondary energy is converted directly into electricity without the need to pass through a stage of mechanical energy [2]. The direct energy conversion methods that nowadays are taken into account in terms of industrial application are: Photovoltaic generation systems (Photovoltaic Solar Cells) Electrochemical energy conversion (Fuel Cells) Magneto hydrodynamic generation (MHD) Electro gas dynamic generation (EGD) Thermo electric power generation In the first two processes the conversion from the primary to the secondary energy form takes place avoiding the conversion in the intermediate thermal energy. The Figure 1 shows the energy conversion stages in the direct generation of electric energy.

Figure 1: Direct energy conversion stages

There are many reasons for the use of new and direct conversion schemes. These can be grouped into three important areas: efficiency, reliability, and the use of new sources of energy. It is hoped that when a processes occurs directly, rather than passing through several steps, it is likely to be more efficient. There are many ways whereby the direct energy conversion of thermal to electrical energy can be obtained.

2. MAGNETOHYDRODYNAMIC POWER GENERATIONThe magneto hydrodynamic power generator is a device that generates electric power by means of the interaction of a moving fluid (usually ionized gas or plasma) and a magnetic field. As all direct conversion processes the MHD generators can also convert thermal energy directly into electricity without moving parts. In this way the static energy converters, with no moving mechanical part, can improve the dynamic conversion, working at temperature higher than conventional processes. The typical configuration of MHD generator is shown in Figure 2.

2.1 Principle MHD power generation process is governed by Faradays law of Electromagnetic Induction. ( i.e. when the conductor moves through a magnetic field, it generates an electric field perpendicular to the magnetic field & direction of conductor). The flow of the conducting plasma through a magnetic field at high velocity causes a voltage to be generated across the electrodes, perpendicular to both the plasma flow and the magnetic field according to Flemings Right Hand Rule.

Figure 3: Magneto Hydro Dynamic Generator(Principle) 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 intensity.The vector F is perpendicular to both v and B according to the right hand rule. 2.2 Construction Its construction is very simple. MHD generator resembles the rocket engine surrounded by enormous magnet. It has no moving parts & the actual conductors are replaced by ionized gas (plasma). The magnets used can be electromagnets or superconducting magnets. Superconducting magnets are used in the larger MHD generators to eliminate one of the large parasitic losses. As shown in figure the electrodes are placed parallel & opposite to each other. It is made to operate at very high temperature, without moving parts. Since the plasma temperature is typically over 2000 C, the duct containing the plasma must be constructed from non-conducting materials capable of withstanding this high temperature. The electrodes must of course be conducting as well as heat resistant. Because of the high temperatures, the non-conducting walls of the channel must be constructed from an exceedingly heat-resistant substance such as yttrium oxide or zirconium dioxide to retard oxidation. It can be considered as fluid dynamo similar to mechanical dynamo. The key components are Superconducting Magnets.

3. Different MHD generator designs In practice a number of issues must be considered in the implementation of a MHD generator such as Generator efficiency, Economics, and Toxic products. These issues are affected by the choice of the MHD generator design. Most popular MHD generators are the Faraday generator and the Hall generator.3.1 Faraday Generator A simple Faraday generator would consist of a wedge-shaped pipe or tube of some non-conductive material. When an electrically conductive fluid flows through the tube, in the presence of a significant perpendicular magnetic field, a charge is induced in the field, which can be drawn off as electrical power by placing the electrodes on the sides at 90 degree angles to the magnetic field. The main practical problem of a Faraday generator is that differential voltages and currents in the fluid short through the electrodes on the sides of the duct. In this generator the electrodes are sectionalized to decrease the circulation of current along the channel and through the electrodes (the Hall effect) and thereby to direct the charge carriers perpendicular to the axis of the channel, toward the electrodes and the load. The greater the Hall effect, the greater the number of sections into which the electrodes must be subdivided. In addition, each pair of electrodes must have its own load, which complicates the design of the equipment.

Figure 3.1.1: Faraday MHD Generator3.2 Hall Generator The most common answer is to overcome the problems of Faradays generator is the Hall effect to create a current that flows with the fluid. The normal scheme is to place arrays of short, vertical electrodes on the sides of the duct. The first and last electrodes in the duct supply the load. Each other electrode is shorted to an electrode on the opposite side of the duct. Losses are less than that of a Faraday generator, and voltages are higher because there is less shorting of the final induced current. However, this design has problems because the speed of the material flow requires the middle electrodes to be offset to catch the Faraday currents. As the load varies, the fluid flow speed varies, misaligning the Faraday current with its intended electrodes, and making the generator efficiency very sensitive to its load.

Figure 3.2.1: Hall MHD Generator

4. DIFFERENT MHD SYSTEMSThere are two types of Magneto Hydrodynamic generation systems. They are Open Cycle MHD system and Closed Cycle MHD system. 4.1 Open Cycle MHD System Temperature in OC MHD is about 2500C. DC Superconducting magnets of 4~6Tesla are used. Here exhaust gases are left out to atmosphere & the capacity of these plants are about 100MW.

Figure 4.1.1: Open cycle MHD Generator4.2 Close Cycle MHD Generator Here exhaust gases are again recycled & the capacities of these plants are more than 200MW. Temperature of Close cycle MHD plants is very less compared to Open cycle MHD plants. Its about 1400C. DC Superconducting magnets of 4~6Tesla are used.

Figure 4.2.1: Close cycle MHD Generator4.3 Different features of MHD Generator Plant To obtain good conducting gases, it is necessary to add cesium or potassium as seed materials and to solve the problem of corrosion. Advances in refractory material are needed. The cost of seeding increases substantially the cost of installed power. The cost of wall material is an important part of the total cost of an MHD generator. Good insulating and refractory materials working for a reasonably long time without deterioration should be found. The problem of high temperatures could be alleviated by the use of some type of non-thermal ionization. The Close cycle MHD Generators are again classified based on energy recirculating types. They are (i) Energy Re-Circulating LNG/MHD System (ii) Energy Re-Circulating Nuclear/Gas Turbine System (iii) Energy Re-Circulating Nuclear/MHD System (iv) CO2 Recovery Type MHD Power System

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