Design And Construction Of A Thermoelectric Generator

INTRODUCTION
A thermoelectric generator is a solid-state device that works similar to solar panels but converts heat, rather than sunlight, directly into electricity. A thermoelectric generator is usually made of bismuth telluride semiconductor junctions that are only several millimeters thick. This differs drastically from the bimetallic junctions that were previously used, which were much thicker. Thermoelectric generators generally do not have any moving parts, except for a fan, and can be used in a wide variety of applications to generate electricity.
In a thermoelectric generator, heat is transferred through a piece of metal such as bismuth telluride, that has a high resistance to heat and low thermal conductivity. As the heat travels through the metal, it is converted into electricity and can then be transferred to a conductor or directly to an electronic device. Generally, many thermoelectric generators are connected to each other in a series in order to generate as much electricity as possible.
Thermoelectric generators are advantageous because they allow systems to retrieve heat that is otherwise wasted in the form of exhaust or mechanical waste. Thermoelectric generators also recover heat that occurs naturally, such as the heat that geothermal vents, volcanoes, hot springs, or high-atmosphere applications produce. Generally, heat is not intentionally produced for a thermoelectric generator, as this would lead to an overall loss of electricity or other resources. Thermoelectric generators are most efficient when retrieving heat over 250 degrees Celsius.
Thermoelectric power generators consist of three major components: thermoelectric materials, thermoelectric modules and thermoelectric systems that interface with the heat source. However, this work discuses the design, construction and performance evaluation of the thermoelectric power generator.

1.1 BACKGROUND OF THE PROJECT
In the last decade, problems related to energy factors (oil crisis), ecological aspects (climatic change), electric demand (significant growth) and financial/regulatory restrictions of wholesale markets have arisen worldwide. These difficulties, far from finding effective solutions, are continuously increasing, which suggests the need of technological alternatives to ensure their solution. One of these technological alternatives is known as distributed generation (DG), and consists of generating electricity as near as possible of the consumption site, in fact like it was made in the beginnings of the electric industry, but now incorporating the advantages of the modern technology [1]. Here it is consolidated the idea of using clean nonconventional technologies of generation that use renewable energy sources (RESs) that do not cause environmental pollution, such as wind, solar (photovoltaic and thermal), hydraulic, among others.
Recently, a rising interest on thermal generation based on solid-state devices such as thermoelectric generators (TEG) has emerged as a feasible option of generation of clean energy, mainly because of the development of new semiconductor materials and of their commercial availability in the existing open markets [3-4]. TEGs allow generating electricity directly and with no moving parts from a temperature difference held across the junction of two dissimilar semiconductor materials. These devices share the major characteristics of photovoltaic (PV) systems, being their advantages the possibility of generating electricity continually while they are provided of heat and the significant reduction of costs, reaching today the sixth part of a PV system. Consequently, TEGs are presently arising as a new option inside the portfolio of renewable energy sources and are becoming serious candidates for applications in DG.
Based on the stated above, the present work proposes the application of this novel technological alternative in distributed generation systems. The development of the TEGs integrated into the distribution power grid is presented and the analysis of the dynamic performance of the device and the impact of its use in electric system are included. This work comprises the detailed modeling of TEGs and the power electronic interface with the electric system, as well as the design of the control scheme of the global system.

1.2 PROBLEM STATEMENT
The presence of moving or rotating devices in conventional electric power generators such as wind turbine, hydropower generator, gas turbine etc causes noise, tears and wears and these problems led to invention of thermoelectric generator. In thermoelectric systems there is no requirement for moving devices such as solution pumps, compressor, and valves since no working fluid is utilized in such systems. Thermoelectric generator produces an abundant clean and noiseless free energy.

1.3 AIM / OBJECTIVE OF THE PROJECT
The main aim of this project is to develop abundant cleaner noise less value effective completely different method of power generation technique for charging the battery still on utilization correct solely the need of usage, that helps to scale backs the world warming still as reduce the facility shortages, load shedding and conjointly we will transfer the transportable generating unit. during this project the conversion of waste heat into generate electricity by exploitation thermoelectric generator. The objectives are:
i. To develop an abundant cleaner and noiseless free energy.
ii. Charge the mobile battery wherever ever waste heat is obtained
iii. Maintain the warmth transfer from hot aspect to cold aspect due to uniform charging mobile battery

1.4 PURPOSE OF THE PROJECT
The purpose of this work is to have a type of generator that function similar to heat engines and are less bulky and also are less efficient than heat engines. This device converts heat energy produced from a heat source directly into electrical energy.

1.5 SCOPE OF THE PROJECT
Thermoelectric generators, also known as TEGs, are devices that convert heat energy into electric energy. These generators accomplish this task by using arrays of specialized circuits known as thermoelectric modules, each of which consists of semiconductor materials — known as p-type and n-type — sandwiched between insulating ceramic substrates. While thermoelectric generators have several benefits, they also have their downsides.

1.6 SIGNIFICANCE OF THE PROJECT
One of the greatest importance of thermoelectric generators lies in the fact that they can derive their power from heat that would otherwise just dissipate into its surroundings. Unlike the case with a standard gasoline or diesel generator, purchasing fuel for a thermoelectric generator is unnecessary, as the generator can “steal” its fuel from any device or machine that creates and releases substantial amounts of heat. These devices can include ovens, burners and furnaces, as well as machines — such as automobiles — that produce heat as a by-product of creating power for other functions, such as propulsion.
The thermoelectric modules that make up thermoelectric generators have solid-state constructions, which make the generators highly durable. “Solid-state” refers to the fact that the modules consist entirely of solid, fixed materials and do not rely on gases or vacuums. In contrast, other modules use tube construction, wherein they pass electrical currents through glass tubes filled with gasses or containing vacuums. Unlike tube modules, solid-state thermoelectric modules are robust and are not prone to cracking or shattering — even when faced with turbulent conditions.

1.7 PROBLEM OF THE PROJECT
Cost: One of the main problems of thermoelectric generators, which as of 2011 has prevented their adoption on a wider scale, lies in their cost. Single thermoelectric module capable of producing 1 watts of electrical power cost more than what it takes to produce 1W of electricity from other means.
Efficiency: most thermoelectric generators have an average efficiency of 4 per cent, which means the generators cannot pass on 96 per cent of the energy they obtain from heat sources. Thermoelectric generator will only operate efficiently when supplying electrical current to a device that has a similar electrical resistance. For example, a 100-watt thermoelectric generator could theoretically power a 100-watt light bulb efficiently but would ultimately waste energy if attempting to power a 30-watt bulb.

1.8 APPLICATIONS OF THE PROJECT
Thermoelectric technology is utilized in military, aerospace, power generation, transportation, and HVAC (heating, ventilation and air conditioning) appliances for particular targets.

1.8 ADVANTAGES OF THERMOELECTRIC GENERATOR
Thermoelectric generator (TEG) offer many advantages such as:
i. It highly reliable,
ii. Has no moving parts,
iii. It is environmentally friendly, when compared with conventional electric power generators.

1.9 PROJECT WORK ORGANISATION
The various stages involved in the development of this project have been properly put into five chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows:
Chapter one of this work is on the introduction to the study. In this chapter, the background, significance, objective, purpose, and problem of the study were discussed.
Chapter two is on literature review of this study. In this chapter, all the literature pertaining to this work was reviewed.
Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed.
Chapter four is on testing analysis. All testing that result accurate functionality was analyzed.
Chapter five is on conclusion, recommendation and references.