Query: A dynamic model for thermoelectric generator applied in waste heat recovery

Candidate papers:

abstract: Thermoelectric devices can provide clean energy conversion and are environmentally friendly. However, few studies have been conducted to understand the dynamic characteristics of (thermoelectric generators) TEGs. The stability of output performance plays a very important role in TEG. Based on the thermoelectric effect and heat transfer theory, a dynamic model for waste heat recovery in a general TEG was developed to asses the influence of heat reservoir and heat sink. The validity of the theoretical model was demonstrated by experiments and it was found that the model prediction agrees well with the experimental results. The dynamic response characteristics, such as hot and cold semiconductor surface temperatures, maximum output power and system efficiency, were studied using this dynamic model. The results showed that enhancing heat dissipation on cold side is the crucial to improve the output performance of TEG, and that the fluctuation of hot reservoir leads to rapid change of output power generated by TEG, which is dangerous to electric devices. The dynamic model proposed in the present study can be used in the design and operation analysis of TEGs.
author_names: Xiaolong Gou

Suwen Yang

Heng Xiao

Qiang Ou
title: A dynamic model for thermoelectric generator applied in waste heat recovery
year: 2013

abstract: Abstract Waste heat recovery using a thermoelectric generator (TEG) is a promising approach for vehicle original equipment manufacturers to reduce fuel consumption and lower CO2 emissions. A TEG can convert otherwise wasted thermal energy from engines to electricity directly for use in the vehicle systems. This paper focuses on the development of a dynamic model of TEG system designed for vehicle waste heat recovery, which is made up of counter flow heat exchangers (HXRs) and commercial thermoelectric modules (TEMs) The model is built from thermoelectric materials into a TEM and then into a TEG system. Compared to other TEG models, the tuning and validation process of the proposed model is more complete. Experiments are done on both a TEM test rig and a heavy duty diesel engine, which is equipped with a prototype TEG on the exhaust gas recirculation (EGR) path. Simulations of steady state operating points as well as the response to typical engine cycle test show good agreement with experimental data. A TEG installed upstream of the after treatment system in a heavy duty truck has been modelled to predict the temperatures and power output in a dynamic driving cycle. The simulation results of temperatures show the model can be used as a basis to develop a control system for dynamic operation to ensure safety operation of TEG and efficient operation of the after treatment system. A comparison of power output of the systems under different scenarios underlines the importance of integration of TEM with HXRs. Based on the simulation results, around 20% average power output increase can be expected by optimizing the thermal contact conductance and the heat transfer coefficient of hot side HXR.
author_names: Song Lan

Zhijia Yang

Rui Chen

Richard K Stobart
title: A dynamic model for thermoelectric generator applied to vehicle waste heat recovery
year: 2018

abstract: The use of thermal energy dissipated from technical processes is an important step on the way towards a more sustainable society. Due to new working fluids and materials, available technologies like the thermal Organic Rankine Cycle or the Thermoelectric Generator are reaching efficiency levels making them also feasible economically. Currently, the decision on one of the existing technologies, the system design, and the applied control strategy is mainly based on rules of thumb. To foster an unbiased approach, in this contribution scalable dynamic simulation models described with the component based modeling language Modelica are proposed. A realistic example shows how these models can be used to comparatively evaluate different system layouts for efficiency and profitability.
author_names: Felix Felgner

Lukas Exel

Georg Frey
title: Model based design and validation of waste heat recovery systems
venue: 2012 IEEE International Energy Conference and Exhibition (ENERGYCON)
year: 2012

abstract: Thermoelectric generator technology,due to its several kinds of advantages,especially its promising applications to recover waste heat,has become a noticeable researcher direction.Thermoelectric technology involves three basic effects,which lead to the temperature distribution being difficult to solve.In order to explore operation law which makes thermoelectric generator have a bigger output power,a mathematical model based on thermoelectric principle and heat transfer theory has been built and was used to solve the temperature distribution of thermoelectric generator.The performance characteristics of thermoelectric generator in different operation conditions have been gained in the objective function of output power by simulating.By the comparison,it is found that reinforcing the heat transfer capability is an effective approach and the water is superior to the air for the cooling effect.The results can provide meaningful guidelines for optimizing operation conditions and improving output power of thermoelectric generator.
author_names: Gou Xiaolong
title: Simulation on Performance of Thermoelectric Generator Applied in Waste Heat Recovery
year: 2012

abstract: Waste heat recovery, using thermoelectric power technology, is a promising approach to reduce fuel consumption and CO2 emissions on passenger cars. However, possible application requires optimizing heat exchangers and defining adequate thermoelectric materials to improve efficiency. A dynamic model has been developed to investigate the application of a thermoelectric generator (TEG) for waste heat recovery in an automotive engine exhaust. The converted electrical energy is used to charge a 12 V battery. The model evaluates the amount of recovered energy over a prescribed drive cycle. It also evaluates the effect of system integration on the TEG performances, such as fuel consumption, temperatures downstream of the TEG and the relative counter pressure. Experiments are done on both a thermoelectric module (TEM) test rig and a diesel engine test rig equipped with a TEG prototype. Simulations of steady operating points show good agreement with experimental data. The results show a maximum power of 42 W generated by the TEG, with a maximum power of 1.5 W per module (corresponding to TEM hot side temperature of 671 K and TEM cold side temperature of 354 K) At the end of the duty cycle, the energy recovered by the vehicle battery is around 27 kJ (7.5 Wh) The engine counter pressure exceeds 30 mbar when the mass flow rate is higher than 36 g s 1. The simulation results of temperatures, pressures, and output power show that the model can be used as a basis to develop a TEG with high performance that ensure safety operation of the engine and the after treatment system.
author_names: A Nour Eddine

H Sara

David Chalet

Xavier Faure

Luc Aixala

M Cormerais
title: Modeling and Simulation of a Thermoelectric Generator Using Bismuth Telluride for Waste Heat Recovery in Automotive Diesel Engines
venue: Journal of Electronic Materials
year: 2019

abstract: A numerical model has been developed to simulate coupled thermal and electrical energy transfer processes in a thermoelectric generator (TEG) designed for automotive waste heat recovery systems. This model is capable of computing the overall heat transferred, the electrical power output, and the associated pressure drop for given inlet conditions of the exhaust gas and the available TEG volume. Multiple filled skutterudites and conventional bismuth telluride are considered for thermoelectric modules (TEMs) for conversion of waste heat from exhaust into usable electrical power. Heat transfer between the hot exhaust gas and the hot side of the TEMs is enhanced with the use of a plate fin heat exchanger integrated within the TEG and using liquid coolant on the cold side. The TEG is discretized along the exhaust flow direction using a finite volume method. Each control volume is modeled as a thermal resistance network which consists of integrated submodels including a heat exchanger and a thermoelectric device. The pressure drop along the TEG is calculated using standard pressure loss correlations and viscous drag models. The model is validated to preserve global energy balances and is applied to analyze a prototype TEG with data provided by General Motors. Detailed results are provided for local and global heat transfer and electric power generation. In the companion paper, the model is then applied to consider various TEG topologies using skutterudite and bismuth telluride TEMs.
author_names: B N Sharma

G Naresh Babu

A Akhil
title: Thermoelectric Generators for Automotive Waste Heat Recovery Systems Part I: Numerical Modeling and Baseline Model Analysis
year: 2017

abstract: Abstract In order to face with the increasing EU restrictions on CO2 emissions from light duty vehicles, concepts such as the engines downsizing, stop/start systems as well as more costly full hybrid solutions and Waste Heat Recovery (WHR) technologies have been proposed in the last years by OEMs. WHR technologies include Thermo Electric Generator (TEG) Organic Rankine Cycle (ORC) and Electric Turbo Compound (ETC) that have been practically implemented on few heavy duty applications but have not been proved yet as effective and affordable solutions for passenger cars. The paper deals with the analysis of opportunities and challenges of TEG and ETC technologies for a compact car, powered by a turbocharged SI engine. Specifically, the benefits achievable by TEG and ETC have been investigated by simulation analyses carried out by a dynamic engine vehicle model, validated against steady state and transient experimental data. The in cylinder processes and friction losses of the engine are modeled by a black box scalable parametric approach while grey box dynamic models are applied for intake/exhaust manifolds and turbocharger. The TEG model is based on existing and commercial thermoelectric materials, specifically Bi2Te3. The simulations have been carried out considering standard driving cycles (i.e. NEDC, WLTC) and the results evidence that significant improvement of fuel economy and CO2 reduction can be achieved by suitable management and configuration of the WHR systems, depending on engine speed and load and auxiliaries demand.
author_names: Ivan Arsie

Andrea Cricchio

Cesare Pianese

Vincenzo Ricciardi

Matteo De Cesare
title: Modeling Analysis of Waste Heat Recovery via Thermo Electric Generator and Electric Turbo Compound for CO2 Reduction in Automotive SI Engines
year: 2015

abstract: In the face of the internationally tightened requirements and regulations for CO2 emissions from the transportation sector, waste heat recovery using a thermoelectric generator (TEG) has become the most significant research interest. A vehicular TEG, converting otherwise wasted thermal energy from engines to electricity directly for use in the vehicle systems, is a promising approach for vehicle original equipment manufacturers (OEMs) to reduce fuel consumption and lower CO2 emissions. This thesis aims to explore the main challenges to be faced in the commercialization of TEGs. Based on a review of the literature, four research gaps have been identified, which are respectively: Translating the material improvements into TEG Performance, Transient behaviors of vehicular TEGs under driving cycles, Fuel saving percentage and cost benefit estimation of TEG, Bidirectional characteristic of TEM and bifunctional vehicular TEG. To directly address these research gaps, a quasi static TEM model, a dynamic TEG model, a semi empirical vehicular TEG model, and a dual model TEM model have been respectively developed and validated through experiments on both TEM test rigs and TEG engine test benches. These developed models are used as tools to investigate the performance of TEG, parameters sensitivity, and integration effects. Model based TEG control, TEG cost benefit ratio and feasibility of a bifunctional TEG are also explored based on the developed models. The simulation results show that TEG power generation is highly sensitive to the heat transfer coefficient of hot side heat exchanger and thermal contact resistance. The TEG installation position is identified as the most important integration effect. It has been found by the simulation result that the fuel saving with TEG installed upstream of the three way catalyst (TWC) is 50% higher than the fuel saving with TEG installed downstream of the TWC. The fuel saving percentage for a skutterudite vehicular TEG, which can generate around 400 600W in constant speed 120km/h, is 0.5 3.6% depending on the integration position in the exhaust line. A 3 minute faster warm up effect of engine oil can be obtained when the bifunctional TEG works in engine warm up mode with electrical current applied.
author_names: Song Lan
title: The role of thermoelectric generator in the efficient operation of vehicles
year: 2018

abstract: A thermoelectric generator (TEG) converts thermal energy into electrical energy corresponding to temperature gradient across both hot and cold surfaces with a conversion efficiency of approximately 5% In spite of the conversion efficiency, TEGs can be implemented effectively for waste heat recovery systems within the power rating of kilowatts. The insufficiency of natural resources, frequently increasing oil costs and emission regulations have become an incentive factor of the recent increased interest in TEG applications. This thesis introduces a practical implementation of the thermoelectric generator for an automotive exhaust system which has a rapid transient response to produce electrical energy from the waste heat which flows through the exhaust pipe. In addition to automotive TE power generator implementation, an H Bridge DC DC converter within the operation of maximum power point tracking method is introduced in this thesis to obtain the maximum power transfer between the thermoelectric power generator and the load. This thesis presents a transient solution to the two dimensional heat transfer equation with variant ambient temperature that determines heat transfer and electrical potential across the thermoelectric pellet. This equation is applied into a designed two dimensional heat transfer MATLAB model and a comparison of simulation and experimental results approves the accuracy of the designed model. In addition to heat transfer simulation, a dynamic large scale thermoelectric power generator simulation program is introduced in this thesis to provide data analysis of actual implementation.
author_names: Volkan Akdogan
title: Thermoelectric power generator for automotive applications
year: 2016

abstract: The US Department of Energy's National Renewable Energy Laboratory (NREL) has developed an integrated heat exchanger/thermoelectric power system analysis tool (in Matlab/Simulink environment) that simultaneously analyzes and optimizes the integrated effects of heat exchanger and thermoelectric power generator (TEPG) performance in light duty passenger (LDP) and heavy duty (HD) vehicle waste heat recovery applications. Part I of this two part paper describes the mathematical basis of this analysis approach as applied to TEPGS using single material and segmented leg thermoelectric (TE) couples. The integrated system analysis approach to heat exchanger/TEPG system performance allows NREL to simultaneously quantify the effects of important system design parameters, and heat exchanger and TEPG device design details on performance and power output in LDP and HD vehicles of interest. Part I discusses system power maximization, potential electrical power available, and cold side cooling mass flow requirements in LDP vehicle exhaust heat recovery applications. The model has been used in Part II of this technical paper to: (1) further investigate the behavior and interdependence of important thermal and TEPG system design parameters, and (2) predict potential TE system power output for a variety of thermal conditions in LDP and HD vehicles.
author_names: Terry J Hendricks

Jason A Lustbader
title: Advanced thermoelectric power system investigations for light duty and heavy duty applications. I
venue: Twenty First International Conference on Thermoelectrics, 2002. Proceedings ICT '02.
year: 2002