Real Thermoelectric Generator Research Articles

Evaluation method for assessing heat transfer enhancement effect on performance improvement of thermoelectric generator systems

The total power output of a thermoelectric generator system can be increased by enhancing the heat transfer performance of its hot-side heat exchanger. However, heat transfer enhancement is usually accompanied by the consumption of additional pump power. Therefore, it is unclear whether the net power output, that is, the difference between the total power output and the pump power, increases. Developing a comprehensive evaluation method based on the net power output is necessary to determine the heat transfer enhancement effect on performance improvement of the system. In this paper, the concept of net power ratio which integrates the total power output and the pump power consumption was proposed to evaluate the heat transfer enhancement effect on the performance improvement of a thermoelectric generator system. Based on a ring-shaped thermoelectric generator, the analytical solution of the net power ratio was theoretically derived. Compared with the numerical and experimental methods, the proposed net power ratio in a thermoelectric generator system is convenient and time-saving with adequate accuracy for engineering applications. Moreover, the application of net power ratio in a real thermoelectric generator system was investigated by case studies. Results show that both the inlet fluid temperature and the mass flow rate affect the net power ratio. When using net power ratio to evaluate the performance improvement of a thermoelectric generator system, net power should also be considered to obtain optimal working conditions for a thermoelectric generator system.

Thermal performance of two heat exchangers for thermoelectric generators

The thermal performance of a heat exchanger is important for the potential application in an integrated solar cell/module and thermoelectric generator (TEG) system. Usually, the thermal performance of a heat exchanger for TEGs is analysed by using 1D heat conduction theory which ignores the detailed phenomena associated with thermo-hydraulics. In this paper, thermal and momentum transports in two different heat exchangers are simulated by means of a steady-state, 3D turbulent flow k-ε model with a heat conduction module under various flow rates. In order to simulate the actual working conditions of the heat exchangers, a hot block with an electric heater is included in the model. The TEG module is simplified by using a 1D heat conduction theory, so its thermal performance is equivalent to a real TEG. Natural convection effects on the outside surfaces of the computational domains are considered. Computational models and methods used are validated under transient thermal and electrical experimental conditions of a TEG. The two heat exchangers designed in this paper have better thermal performance than an existing heat exchanger for TEGs. More importantly, the fin heat exchanger is more compact and efficient than the tube heat exchanger.

New Configurations of Micro Plate-Fin Heat Sink to Reduce Coolant Pumping Power

The thermal resistance of heat exchangers has a strong influence on the electric power produced by a thermoelectric generator (TEG). In this work, a real TEG device is applied to three configurations of micro plate-fin heat sink. The distance between certain microchannels is varied to find the optimum heat sink configuration. The particular focus of this study is to reduce the coolant mass flow rate by considering the thermal resistances of the heat sinks and, thereby, to reduce the coolant pumping power in the system. The three-dimensional governing equations for the fluid flow and the heat transfer are solved using the finite-volume method for a wide range of pressure drop laminar flows along the heat sink. The temperature and the mass flow rate distribution in the heat sink are discussed. The results, which are in good agreement with previous computational studies, show that using suggested heat sink configurations reduces the coolant pumping power in the system.

Thermoelectric properties and efficiency measurements under large temperature differences

The maximum efficiency of a thermoelectric generator is determined by the material's dimensionless figure of merit ZT. Real thermoelectric material properties are highly temperature dependent and are often measured individually using multiple measurement tools on different samples. As a result, reported ZT values have large uncertainties. In this work we present an experimental technique that eliminates some of these uncertainties. We measure the Seebeck coefficient, electrical conductivity, and thermal conductivity of a single element or leg, as well as the conversion efficiency, under a large temperature difference of 2-160 degrees C. The advantages of this technique include (1) the thermoelectric leg is mounted only once and all measurements are in the same direction and (2) the measured properties are corroborated by efficiency measurements. The directly measured power and efficiency are compared to the values calculated from the measured properties and agree within 0.4% and 2%, respectively. The realistic testing conditions of this technique make it ideal for material characterization prior to implementation in a real thermoelectric generator.

Thermodynamic Analysis of Waste-Heat Thermoelectric Generators

A thermodynamic analysis of a real waste-heat thermoelectric generator is investigated. The thermoelectric generator is considered as a heat engine cycle process with internal irreversibilities. The efficiency of the thermoelectric generator is expressed in terms of two non-dimensional parameters which are to be optimized. A finite-time thermodynamic analysis is used to optimize the temperatures of the hot and cold junctions of the real thermoelectric generator. A comparison between ideal and real waste-heat thermoelectric generators is demonstrated.

System Modelling and Controller designed for Thermoelectric Generator using a First Order Plus Dead Time

This paper discusses the design, implementations and verification of Thermoelectric generator (TEG) modules using a first order plus dead time (FOPDT) in a Matlab/Simulink™ program. The models proposed in this paper were designed to improve the thermoelectric generator performance under the condition of the inlet fuel control system with performed load connections. The tuning for the proportionalintegral-derivative (PID) controller was done with Dahlin synthesis tuning and Quarter decay ration tuning formulas. The comparisons result of simulations model from real TEG machine were examined and analysed against controller from simulation model to study the TEG system.