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The issue of energy co-generation using thermoelectric generators

Chmielewski A., Lubikowski K., Radkowski S., Wikary M., Mączak J.

Archiwum Motoryzacji

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2015

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Vol. 67, no. 1

3--10, 133--140

EN

The development of the renewable energy sources technologies and the energy policy emphasise the energy co-generation systems. In the automotive industry, investments are located in the development of heat pumps, Stirling engines, energy accumulators, gas turbines, piezo mats, suspensions and enfeeblements, linear motors, and other energy retrieval systems retrieving energy that is expelled in the process of the combustion of the fuel and air mixture in conventional combustion engines [1,2] and lost irretrievably. The energy co-generation systems increase efficiency in the use of the energy contained in the fuel and air mixture. Currently, there is a tendency of combination of the energy micro-cogeneration systems with other vehicle systems, e.g. motor control systems, motor power supply systems, safety systems, etc. [3-8]. One of such ways is the retrieval of heat energy thanks to thermoelectric generators (TEG) using the Seebeck effect.

PL

Rozwój technologii odnawialnych źródeł energii i polityka energetyczna kładą nacisk na systemy kogeneracji energii. W przemyśle samochodowym inwestuje się w rozwój pomp cieplnych, silników Stirlinga, akumulatorów energii, turbin gazowych, mat, zawieszeń i wyciszeń piezoelektrycznych, silników liniowych oraz innych systemów odzyskiwania energii, która, wydalana w procesie spalania mieszanki paliwowo-powietrznej w konwencjonalnych silnikach spalinowych [1,2], jest bezpowrotnie tracona. Systemy kogeneracyjne zwiększają efektywność wykorzystania energii zawartej w mieszance paliwowo-powietrznej. Aktualnie istnieje tendencja do łączenia systemów mikrokogeneracji energii wraz z innymi systemami istniejącymi w pojeździe, np. systemami sterowania silnikiem, zasilania silnika, systemami bezpieczeństwa itp. [3-8]. Do jednego z takich sposobów należy odzysk energii cieplnej dzięki termoelektrycznym generatorom (TEG – z ang. thermoelectric generators) wykorzystującym zjawisko Seebecka.

2

Temperature stability of the exhaust system using the TEG in the task of cogeneration energy

Lubikowski K., Radkowski S., Szczurowski K., Szulim P.

Zeszyty Naukowe Instytutu Pojazdów / Politechnika Warszawska

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2013

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z. 4/95

107--113

EN

Acquisition of energy from sources other than natural is discussed more and more nowadays. Many research centers deal with the issue of energy recovery and use of energy from renewable sources. Automotive industry places increasing stress on the development and implementation of solutions leading to increased energy-efficiency of vehicles. Since a combustion engine uses less than half of the energy produced in the process of fuel burning, thus thermal energy recovery and its conversion into electrical energy enjoys more and more interest. The article presents the method of controlling the flow of exhaust gases in the exhaust system of a combustion engine operating in a testbed. Measuring equipment was used for determining the respective temperatures. The publication presents an example of use of thermoelectric generators for recovering energy from the lost heat while at the same time using a system for controlling the flow exhaust fumes. The way in which the temperature of exhaust fumes affects the surface from which thermal energy is collected is demonstrated. The boundary operating conditions of TEG are also discussed.

PL

W dzisiejszych czasach mówi się coraz częściej o pozyskiwaniu energii z innych źródeł niż naturalne. Wiele ośrodków naukowo-badawczych zajmuje się problematyką odzyskiwania energii i wykorzystywania energii ze źródeł odnawialnych W środowiskach związanych z motoryzacją wiele uwagi poświęca się zagadnieniom zwiększenia efektywności energetycznej pojazdów. Ponieważ silnik spalinowy wykorzystuje mniej niż połowę energii wytwarzanej w procesie spalania, coraz większe zainteresowanie budzi problematyka odzyskiwania energii cieplnej i jej konwersja na energię elektryczną. W artykule przedstawiono regulacji przepływu strumienia spalin w układzie odprowadzania spalin w silniku spalinowym pracującym na stanowisku laboratoryjnym. Do wyznaczenia temperatur wykorzystano sprzęt pomiarowy. W publikacji przedstawiono przykład wykorzystania termoelektrycznych generatorów do odzysku energii z ciepła traconego, jednocześnie wykorzystując układ regulacji strumienia spalin. Pokazano jak wpływa temperatura spalin na powierzchnię z której odbierana jest energia cieplna. Oraz opisano cieplne warunki brzegowe pracy TEG.

3

Environmental influences on the work of the TEG in the exhaust system

Lubikowski K., Radkowski S., Rokicki K., Szczurowski K.

Zeszyty Naukowe Instytutu Pojazdów / Politechnika Warszawska

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2013

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z. 4/95

99--105

EN

Demand for energy continues to grow while non-renewable natural sources of energy are running out. Oil extraction is becoming increasingly difficult and expensive. Also other sources of energy are used, including natural gas, shale gas, solar energy and wind energy, but still the discussions about effective use of energy and its recovery are gaining importance. New systems and methods of re-use of lost energy, including thermal energy, are being developed in automotive industry. The publication presents an example of use of thermoelectric generators for recovering energy from the lost heat while at the same time using a system for controlling the flow of the exhaust fumes. A control system has significant influence on the temperature on the warm side of TEG. While knowing the temperature-related limitations of TEG’s, the temperature should be controlled in such a way so that it does not exceed 140ºC. At the same time the temperature of 200ºC is quoted by the manufacturer as the critical temperature for semi-conductor connectors.

PL

Aktualnie cywilizacyjne zapotrzebowanie na energię rośnie, a nieodnawialne naturalne źródła energii nieodwracalnie się kończą. Wydobycie ropy jest coraz trudniejsze i coraz droższe. Wykorzystywane są również inne źródła energii, takie jak gaz ziemny, gaz łupkowy, energia słoneczna, energia wiatrów, jednak coraz częściej mówi się o efektywnym wykorzystaniu energii i odzysku energii. W motoryzacji powstają coraz to nowsze systemy i sposoby ponownego wykorzystania traconej energii, w tym także energii cieplnej. W publikacji przedstawiono przykład wykorzystania termoelektrycznych generatorów do odzysku energii z ciepła traconego, jednocześnie wykorzystując układ regulacji strumienia spalin. Układ regulacji wpływa znacząco na temperaturę strony ciepłej TEG. Znając ograniczenia temperaturowe TEG należy kontrolować tą temperaturę by nie przekroczyła wartości 140ºC. Jednocześnie producent podaje temperaturę 200º jako temperaturę krytyczną dla złączy półprzewodnikowych.

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Research and simulation work of TEG in cogeneration task of the exhaust system

Chmielewski A., Lubikowski K., Radkowski S., Szczurowski K.

Journal of KONES

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2013

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Vol. 20, No. 2

41--47

EN

One of the main directions of development of power transmission systems in vehicles involves improvement of energy efficiency of combustion engines, especially reduction of the loss related to waste heat in cooling and exhaust systems. The traditional role of the exhaust system is to remove exhaust gases from a combustion engine and muffle the noise created during the engine’s operation. Relevant distribution of temperatures along the entire length of the exhaust system is a very important element in such a complex structure. The examples could be the particulate solids filter or the converter which have to reach a relevant temperature to operate properly while the temperature’s growth is simultaneously restricted due to the limitations associated with the materials used. The research was conducted while using the ECOTEC 1.8 litre engine from Opel, the X18XE model. The engine was installed in a tested, in the mechatronic lab at the Faculty of Automotive and Construction Machinery Engineering (SIMR) of Warsaw University of Technology. The paper reviews the energy efficiency of TEG depending on deferent parameters of gas stream an weather conditions. This is original value of this paper. The results of the experiment are presented in the last section of the article.

5

Thermal analyses of exhaust system on combustion engine

Dybała J., Lubikowski K., Rokicki K., Szulim P., Wikary M.

Journal of KONES

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2012

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Vol. 19, No. 4

173-178

EN

Nowadays there are more and more discussions on acquisition of energy from sources other than natural sources of energy. Many scientific research centres deal with the issue of energy recovery as well as use of energy from renewable sources. The communities associated with the automotive industry devote a lot of attention to the issue of improving the energy efficiency of vehicles. Since a combustion engine uses less than half of the energy produced during the combustion process, thus the issues of recovery of thermal energy and its conversion into electrical energy evoke increasing interest. The article presents the process of examination of the temperature of the exhaust system in a car engine operating in a laboratory environment. Measuring equipment was used to the temperatures' determine. Analysis of distribution of temperatures in the exhaust system creates grounds for rational selection of the places where the thermal energy recuperation systems should be installed. At present, the possibilities of recovery of thermal energy are still seriously restricted by the properties of the materials of which the elements of the thermal energy recovery systems are made. High propensity of these elements to thermal defects is a serious problem in practical application of these materials in thermal energy recovery systems. The results obtained in an experiment serve as the basis for determining the locations where thermoelectric generators should be installed while accounting for their thermal limitations.

6

Energy scavenging in a vehicle's exhaust system

Lubikowski K., Radkowski S., Szczurowski K., Wikary M.

Journal of KONES

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2012

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Vol. 19, No. 3

253-261

EN

Present- day development of power transmission systems, especially the ones based on combustion engines, is trying to cope with the issue of improving the energy efficiency of energy processing systems. One of the directions is to use the techniques of thermal energy recovery from an engine's exhaust system. Vast part of the energy produced while burning the air- fuel mixture is lost in the cooling and exhaust systems. Research in this area was conducted by numerous teams, both abroad and in Poland, while focusing on use of Peltirea cells. The results of their research demonstrated small efficiency of these cells. In this paper, the authors have focused on modifications of the exhaust system in order to improve heat exchange between the exhaust system's elements and TEG. The research was conducted while using the ECOTEC 1.8 litre engine from Opel, the X18XE model. The engine was installed in a testbed, in the mechatronic lab at the Faculty of Automotive and Construction Machinery Engineering (SIMR) of Warsaw University of Technology. Spartan HE923 radiators were installed on the cold end of the module. The paper presents the results of the research related to interworking of TEG's with the exhaust system's heat-generating elements of various shapes. The paper reviews the energy efficiency of TEG depending on diverse parameters of gas flow. A parallel system has been assumed (controlled stream and pressure of the flowing exhaust gases without any interference as regards the speed of the of combustion engine). The factor-related experiment accounts for the influence that the pressure and temperature difference, depending on the volume and discharge of exhaust fumes, have on the efficiency of TEG for the same temperature. The results of the experiment are presented in the last section of the article.