Study of Thermoelectric Generation by Motorcycle Exhaust

• Main Authors: Chen Tai Yuan, 陳岱原
• Other Authors: Kao Mu Jung
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/48t9h2

碩士 === 國立臺北科技大學 === 車輛工程系所 === 104 === The study explores installation of bismuth telluride thermoelectric generator (TEG) at the exhaust pipe of motorcycle for generation of electricity from waste heat, and designs enlargement of temperature difference between the cold and hot ends of TEG through cooling of air and water. Currently, the existing 4-stroke cycle motorcycle engines can actually achieve an effective use of fuel by about 30% only, with the rest of the 70% consumed and wasted due to heat dissipation and exhaust of waste heat. Besides, around 30% of the wasted thermal energy produced from burning of fuel emits to the atmosphere along with the exhaust gas of the engine. Therefore, the paper conducts tests, analysis and research of the ternary thermal power generator, which is composed of Te, Bi, Sb and Se. Thermoelectric generator is installed at the exhaust pipe of motorcycle for actually testing the thermal to electric energy conversion and analyzing the efficacy of thermoelectric generation via the effect of temperature difference. According to Seebeck effect and the related theories, the thermoelectric semiconductor in ternary thermal power generator enables thermal to electric energy conversion via temperature difference. For a loop formed by connecting two dissimilar metals, it is proved that when there is temperature difference between the two ends for connection, electric current will be produced in the loop, and thermo-electromotive force will exist simultaneously. Such a thermoelectric effect created by temperature difference can increase the amount of electricity generated from waste heat recovery. The study focuses on effect of temperature difference under different RPM levels and measures the related data from an experiment in order to discuss the application of enhancing waste heat recovery efficiency of motorcycle engines. For the process of experiment, thermoelectric module (TEM) is actually installed on the platform of dynamic test machine. Through air cooling and water cooling for TEG of motorcycle exhaust waste heat, the study tests the temperature difference between the cold and hot ends as well as electricity generation, and also tests the efficacy of waste heat recovery system for exhaust pipe of motorcycle. All the data acquired in experiments are further analyzed in the study. As known from the experimental results, as the temperature difference between the cold and hot ends of ternary thermoelectric module (TEM) is greater, the output power of its TEG is also increased accordingly. The study also compares the relative relationship between air cooling and water cooling of TEM towards rotational speed of engine, as well as the results of overall electricity generation efficiency and ZT value. It is known that through dissipating heat of TEG by water cooling, the temperature difference between the cold and hot ends may reach 208K; and the power of electricity generation is increased by 281.43% when compared with air cooling. When engine speed is 70 km/hr, the greatest electricity generation is 63.09 W. Experimental results show that the thermal to electric energy conversion effect of heat dissipation by water cooling is obviously better than other ways. It is hoped that the above information is referential for follow-up studies.