International Journal on “Technical and Physical Problems of Engineering” (IJTPE) Published by International Organization of IOTPE ISSN 2077-3528 IJTPE Journal www.iotpe.com ijtpe@iotpe.com December 2013 Issue 17 Volume 5 Number 4 Pages 113-117 113 THERMOELECTRIC ELEMENT ASSIGNED AS ELECTRICGENERATOR FROM WASTE HEAT G. Kavei 1 A.A. Khakpour 2 A. Hadifakoor 1 S. Nikbin 1 A. Kavei 3 1. Material and Energy Research Centre, Tehran, Iran g-kavei@merc.ac.ir, aidin.hadifakoor@gmail.com, saeedn1986@gmail.com 2. Tehran Branch, Islamic Azad University, Tehran, Iran, ali_kh134@yahoo.com 3. Department of Chemistry, Imperial College London, UK, a.kavei13@imperial.ac.uk Abstract- The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice-versa. A thermoelectric device creates a voltage when temperature differ on side respect to next side. At the atomic scale, the temperature gradient causes charge carriers in the material to diffuse from the hot side to the cold side. In this case, electricity generated as a measure or change of the temperature difference of hot and cold sides of the thermoelement. The investigation involved using waste heat as input source. For this purpose, 72 bismuth telluride thermoelectric modules were used for energy conversion. The number of modules and their arrangement were delicate to select, where the power generated at the expense of temperature differences appeared between two sides of thermoelement. The 100 W generator was tested on chimneys, which outlet the hot gases to the atmosphere. Many of the design features, e.g. heat sink and fin designs were changed during this development as more information was obtained. The involved parameters of the generator are considered. Keywords: Thermoelectric, Electric Generator, Waste Heat, Thermoelement. I. INTRODUCTION Most of the energy we use today comes from coal, oil, and natural gas. They are fossil fuels. They take millions of years to form. We can’t make more quickly. They are nonrenewable. A good way to save energy is by not wasting it. Broad societal needs have focused attention on technologies that can reduce ozone depletion, greenhouse gas emissions, and fossil fuel usage. Electrical power, are increasingly being seen as having the potential to make important contributions to reducing CO 2 and greenhouse gas emissions and providing cleaner forms of energy. Solid-state systems with more familiar mechanical are the providers of electrical power generation, such as air conditioners, refrigerators and turbine engines. These classes have complementary regimes in which they can provide clean energy performance [1-2]. Conventional metallic thermocouples are made from metal or metal alloys. They generate small voltages, typically tens of microvolts per degree temperature difference by the Seebeck effect. Thermoelectric power generator offers several distinct advantages over other technologies [3-5]: They are extremely reliable (typically exceed 100,000 Hours of steady-state operation). Silent in operation since they have no mechanical moving parts and require. Considerably less maintenance; They are simple, compact and safe; They have very small size and virtually weightless; They are capable of operating at elevated temperatures; They are suited for small-scale and remote applications Typical of rural power supply, where there is limited or no electricity; They are environmentally friendly; They are not position-dependent; and They are flexible power sources. The major drawback of thermoelectric power generator is their relatively low conversion efficiency (typically ~5% [6]). This has been a major cause in restricting their use in electrical power generation of specialized fields with extensive applications where reliability is a priority and cost is not considered. Applications over the past decade included industrial instruments, military, medical and aerospace [3, 6], and for portable or remote power generation [7]. However, in recent years, an increasing concern of environmental issues of emissions, in particular global warming has resulted in extensive research into unconventional technologies of generating electrical power and thermo- electric power generation has emerged as a promising alternative green technology. Vast quantities of waste heat are discharged into the earth’s environment much of it at temperatures which are too low to recover using conventional electrical power generators. Thermoelectric power generation (also known as thermoelectricity) offers a promising technology in the direct conversion of low- grade thermal energy, such as waste-heat energy, into electrical power [8].