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High efficiency thermoelectric generators (TEG) can recover waste heat from both industrial and private sectors. Thus, the development and deployment of TEG may represent one of the main drives for technological change and fuel substitution. This paper will present an analysis of system efficiency related to the integration of TEG into thermal energy systems, especially Combined Heat and Power production (CHP). Representative implementations of installing TEG in CHP plants to utilize waste heat, wherein electricity can be generated in situ as a by-product, will be described to show advantageous configurations for combustion systems. The feasible deployment of TEG in various CHP plants will be examined in terms of heat source temperature range, influences on CHP power specification and thermal environment, as well as potential benefits. The overall conversion efficiency improvements and economic benefits, together with the environmental impact of this deployment, will then be estimated. By using the Danish thermal energy system as a paradigm, this paper will consider the TEG application to district heating systems and power plants through the EnergyPLAN model, which has been created to design suitable energy strategies for the integration of electricity production into the overall energy system.

We discuss a novel tool based on heat flow diagrams for analyzing irreversible processes associated with thermoelectric devices and discuss some ambiguous descriptions and errors in related investigations. We consider thermoelectric generators as a paradigm of a heat engine cycle and determine the heat flow distribution by treating the one-dimensional heat transfer differential equation. Representative heat flow diagrams are used to study the influence of internal and external irreversible processes of heat conduction and Joule heat generation.

When a thermoelectric generator (TEG) and its external load circuitry are considered together as a system, the codesign and cooptimization of the electronics and the device are crucial in maximizing the system efficiency. In this paper, an accurate TEG model is proposed and implemented in a SPICE-compatible environment. This model of thermoelectric battery accounts for all temperature-dependent characteristics of the thermoelectric materials to include the nonlinear voltage, current, and electrothermal coupled effects. It is validated with simulation data from the recognized program ANSYS and experimental data from a real thermoelectric device, respectively.Within a common circuit simulator, the model can be easily connected to various electrical models of applied loads to predict and optimize the system performance. Udgivelsesdato: March When a thermoelectric generator (TEG) and its external load circuitry are considered together as a system, the codesign and cooptimization of the electronics and the device are crucial in maximizing the system efficiency. In this paper, an accurate TEG model is proposed and implemented in a SPICE-compatible environment. This model of thermoelectric battery accounts for all temperature-dependent characteristics of the thermoelectric materials to include the nonlinear voltage, current, and electrothermal coupled effects. It is validated with simulation data from the recognized program ANSYS and experimental data from a real thermoelectric device, respectively.Within a common circuit simulator, the model can be easily connected to various electrical models of applied loads to predict and optimize the system performance.

A flat wall-like thermoelectric generation system is developed for applications in exhaust heat of kilns. The design of the whole experimental setup is presented. The essential performance of the thermoelectric generation system is tested, including open-circuit voltage, output power, and system conversion efficiency. The results illustrate that, when heat source insulation is not considered, the system conversion is efficient at hot-side temperatures between 120°C and 150°C. In addition, the nonuniformity of heat transfer is found to significantly affect the power-generating ability of the system. System-level simulation is carried out using a quasi-one-dimensional numerical model that enables direct comparison with experimental results. The results of both experiment and simulation will provide a foundation to improve and optimize complex thermoelectric generation systems.

A thermoelectric generation system (TEGS) used in the practical industry of waste heat recovery consists of the fluidic heat sources, the external load circuitry, and many thermoelectric modules (TEMs) connected as a battery bank. In this paper, a system-level model is proposed to seamlessly integrate the complete fluid-thermal-electric-circuit multiphysics behaviors in a single circuit simulator using electrothermal analogy. First, a quasi one-dimension numerical model for the thermal fluids and their nonuniform temperature distribution as the boundary condition for TEMs is implemented in simulation program with integrated circuit emphasis (SPICE)-compatible environment. Second, the electric field calculation of the device-level model is upgraded to reflect the resistive behaviors of thermoelements, so that the electric connections among spatially distributed TEMs and the load circuitry can be freely combined in the simulation. Third, a hierarchical and TEM-object oriented strategy are developed to make the system modeling as well as the design scalable, flexible, and programmable. To validate the proposed system model, a TEGS, including eight TEMs is constructed. Through comparisons between simulation results and experimental data, the proposed model shows sufficient accuracy so that a straightforward cooptimization of the entire TEGS of large scale can be carried out.

This paper presents a numerical model of an exhaust heat recovery system for a high temperature polymer electrolyte membrane fuel cell (HTPEMFC) stack. The system is designed as thermoelectric generators (TEGs) sandwiched in the walls of a compact plate-fin heat exchanger. Its model is based on a finite-element approach. On each discretized segment, fluid properties, heat transfer process and TEG performance are locally calculated for higher model precision. To benefit both the system design and fabrication, the way to model TEG modules is herein reconsidered; a database of commercialized compact plate-fin heat exchangers is adopted. Then the model is validated against experimental data and the main variables are identified by means of a sensitivity analysis. Finally, the system configuration is optimized for recovering heat from the exhaust gas. The results exhibit the crucial importance of the model accuracy and the optimization on system configuration. Future studies will concentrate on heat exchanger structures.

In thermoelectric generators, the heat sources are usually fluids or flames. To simplify the co-design and co-optimization of the fluid or combustion system and the thermoelectric device, which are crucial for maximizing the system performance, a three-dimensional thermoelectric generator model is proposed and implemented in a computational fluid dynamics (CFD) simulation environment (FLUENT). This model of the thermoelectric power source accounts for all temperature dependent characteristics of the materials, and includes nonlinear fluid-thermal-electric multi-physics coupled effects. In solid regions, the heat conduction equation is solved with ohmic heating and thermoelectric source terms, and user defined scalars are used to determine the electric field produced by the Seebeck potential and electric current throughout the thermoelements. The current is solved in terms of the load value using user defined functions but not a prescribed parameter, and thus the field-circuit coupled effect is included. The model is validated by simulation data from other models and experimental data from real thermoelectric devices. Within the common CFD simulator FLUENT, the thermoelectric model can be connected to various CFD models of heat sources as a continuum domain to predict and optimize the system performance.

The 3D compact model of a thermoelectric cooler in the CFD approach is an essential technique for computationally realistic design of many industrial thermal management applications. The first objective of this paper is to develop a “black box”-like model for thermoelectric coolers as well as a method to formulate the effective material properties for the compact model based on the manufactures’ datasheets. Second, a highly detailed and physical thermoelectric cooler model is implemented to carry out virtual experiments when the cooler datasheet is not available. A number of close comparisons validate that the compact model and parameter extraction are accurate enough, and the computation time and size are significantly lower than the physical model. The compact model is also demonstrated to be helpful in evaluating the thermal system components such as an air-cooled heat sink, so that the system-level thermal management optimization is possible without complex, multi-scale computation.