Thermoelectric conversion of waste heat from IC engine-driven vehicles: A review of its application, issues, and solutions

Patowary, Rupam; Baruah, D.C.

doi:10.1002/er.4021

Cited by 30 publications

(22 citation statements)

References 65 publications

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“…Another attractive solution to harvest the energy released by exhaust gases consists on transforming it directly into electrical power avoiding moving parts and the corresponding maintenance costs. This is possible when using thermoelectric generators (TEGs), which produce electricity when there is a temperature difference across the module faces because of the Seebeck effect [2,3,17,18]. The exhaust gases heat the hot face and a cooling circuit keeps the opposite face (cold face) at as low a temperature as possible.…”

Section: Waste Heat Recovery Systemsmentioning

confidence: 99%

Efficiency improvement of vehicles using temperature controlled exhaust thermoelectric generators

Brito

Pacheco

Vieira

et al. 2020

Energy Conversion and Management

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One of the main obstacles for the use of thermoelectric generators (TEGs) in vehicles is the highly variable thermal loads typical of driving cycles. Under these conditions it will be virtually impossible for a conventional heat exchanger to avoid both thermal dilution under low thermal loads and TEG overheating under high thermal loads. The authors have been exploring an original heat exchanger concept able to address the aforementioned problems. It uses a variable conductance thermosiphon-based phase-change buffer between the heat source and the TEGs so that a nearly constant, optimized temperature is obtained regardless of operating conditions. To the best of the authors' knowledge, the thermal control feature of the system is unique among existing TEG concepts. The novelty of the present work is the actual computation of operating pressure and temperature and the corresponding vaporization and condensation rates inside the thermosiphon system during driving cycles along with the assessment of the influence of the volumes and pre-charge pressure on electrical output. The global energy and emission savings were also computed for a typical yearly driving profile. It was observed that indeed the concept has unparalleled potential for improving the efficiency of vehicles using TEGs, with around 6% fuel and CO2 emissions savings using the system. This seems a breakthrough for such light duty applications since the efficiency of conventional (passive) systems is strongly deprecated by thermal dilution under low thermal loads and the need to bypass high thermal load events to avoid overheating. On the contrary, the present concept allows the control of the hot face temperature of the TEGs even under highly variable thermal load (i.e. driving cycle) environments.

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Section: Waste Heat Recovery Systemsmentioning

confidence: 99%

Efficiency improvement of vehicles using temperature controlled exhaust thermoelectric generators

Brito

Pacheco

Vieira

et al. 2020

Energy Conversion and Management

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“…There are two types of studies on the thermoelectric generation (TEG) application, one is using it with the traditional system, and the other one is using TEG directly. For TEG traditional joint system, there are many studies on photovoltaic cell‐thermoelectric generator, thermoelectric stoves, and thermoelectric heat recovery . YangCai et al proposed two new structures of geothermal‐based organic Rankine cycle with TEG, and improved system energy efficiency effectively.…”

Section: Introductionmentioning

confidence: 99%

A cascaded thermoelectric generation system for low‐grade heat harvesting

Shen

Gou

Xu³

et al. 2020

Int J Energy Res

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Summary Thermoelectric generation (TEG) has its unique advantages in terms of distributed energy supply, low‐grade heat recovery, and clean energy technology, but its low efficiency has constrained its application and promotion seriously. In order to obtain satisfactory efficiency and realize the adaptability to different heat sources, a novel cascaded TEG system (CTEG) is proposed. According to the temperature of heat source, three types of thermoelectric modules are used in the generator system. The module arrangement, cooling medium, and mode directly affect the performance of this whole system, since that the detailed model and CFD simulation were conducted to obtain the optimal collocation. Based on the optimization modeling, a CTEG prototype was constructed. From the experimental results, the efficiency of the CTEG achieved 5.92%, which significantly improved about 21.56% compared with the TEG which only contains one stage. Moreover, the key parameters of the system were identified. The stability and the improvement of the system were discussed comprehensively. For TEG system, CTEG increase the utilization of high‐temperature heat sources, but also provides a structure for a TEG adapting to multiple temperature heat sources.

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“…For TEGs technology to become effective a minimum thermal conversion efficiency of 10% is required at a feasible price. This corresponds to a ZT value of more than 2 [19]. The PbTe -TAGS from TECTEG can achieve 12% conversion efficiency however, these modules can cost up to $7000 per module rated at a maximum power output of 58 W. This technology is too expensive for widespread applications in the automotive industry but can be effective for industrial uses.…”

Section: Thermoelectric Materialsmentioning

confidence: 99%

“…The average electrical power requirement for modern light duty commercial vehicles can range from 500 W to 1.5 kW depending on the electrical requirement of the vehicle and can increase up to 4 kW in for medium duty trucks. The increased demand for electrical power is met through using larger alternators, which are only ~50-60% mechanically efficient [19]. Alternators consume roughly around 1-5% of engine power thereby having a direct effect on increased fuel consumption [60].…”

Section: Positioning the Thermoelectric Generatormentioning

confidence: 99%

“…Bi2Te3 has an energy conversion efficiency of 5-7% and a ZT ~ 1 which still amongst top performing TE materials however their conversion efficiency falls rapidly at temperatures over 500 K [19]. TEGs that a are constructed solely from Bi2Te3 become expensive through the subsystems they require to operate safely by keeping the hot side temperature below 520 K, which is the temperature at which module damage occurs.…”

Section: Thermoelectric Module Selectionmentioning

confidence: 99%

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Driven by recent changes to carbon emissions legislation car manufacturers are required to come up with innovative ways of reducing fuel consumption and CO2 emissions on their vehicles. It is estimated that roughly 25% of the fossil fuel energy being burnt in the combustion process is utilized for mobility, 5% is lost in auxiliary systems, 30% lost in the coolant and 40% is lost in the form of waste heat through the exhaust and other heat radiating components [1]. A thermoelectric generator (TEG), as a waste heat recovery system, relies on the Seebeck and Peltier effects which describe how a temperature difference across two dissimilar semiconductors, metals or other materials can create an electric potential across the module. This electric potential allows current to flow which may be harvested for further use as useful power. TEGs are solid-state devices which makes for a robust and reliable system. A TEG consists out of thermoelectric modules sandwiched between a heat sink and a heat source. Heat exchangers (HXR) are used to enhance heat transfer between the heat sink and heat source. The idea for an automotive TEG is to extract heat from the exhaust flow of an internal combustion engine with the hot side HXR and rejecting heat through diverting the coolant line of the vehicle to flow through the cold side HXR. The temperature gradient that this imposes on the thermoelectric modules enables a current to flow which can be converted it into power. In this work open-cell metal foam heat exchangers are considered for the exhaust gas flow HXR due to their superior thermal capabilities, light weight, high surface area and high permeability. Additionally, this work proposes to position the TEG in the exhaust gas recirculation (EGR) path of diesel vehicle. In most modern diesel vehicles, the EGR systems are equipped with both a hot and cold side HXR, positioned on a bypass duct and controlled through an EGR valve. This is most of the infrastructure that a TEG requires for safe operation, therefor integrating these systems minimises cost and improves the financial feasibility of the system. The energy recovered by the thermoelectric generator may be used to reduce the electrical load on the alternator and thereby reduce the mechanical load from the alternator on the engine. Reducing the load on the engine is directly proportional to a reduction in fuel consumption and reduced CO2 emissions. The feasibility of implementing TEGs is limited by the thermoelectric materials' energy conversion efficiency. From an economic standpoint the implementation of TEGs is only feasible for commercialization in medium to heavy-duty diesel engines at an average reduction in overall fuel consumption of ~ 4% from implementing a TEG.

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Thermoelectric conversion of waste heat from IC engine-driven vehicles: A review of its application, issues, and solutions

Cited by 30 publications

References 65 publications

Efficiency improvement of vehicles using temperature controlled exhaust thermoelectric generators

Efficiency improvement of vehicles using temperature controlled exhaust thermoelectric generators

A cascaded thermoelectric generation system for low‐grade heat harvesting

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