Thermoelectric generator with additively manufactured functionally graded materials

Abstract

Thermoelectric generator for converting a temperature gradient into electrical energy, comprising a plurality of thermoelectric elements arranged between a hot-side interface and a cold-side interface, characterized in that the thermoelectric elements are manufactured by additive manufacturing through three-dimensional printing and consist of functionally graded materials, wherein the material composition varies continuously or stepwise along a heat flow direction, such that a gradient of electrical conductivity, thermal conductivity and Seebeck coefficient is generated within the thermoelectric elements.

Description

Field of invention

[0001] The present invention relates to the technical field of thermoelectric energy conversion and, in particular, to a thermoelectric generator for converting a temperature gradient into electrical energy. The invention relates specifically to thermoelectric generators in which thermoelectric elements are arranged between a hot side and a cold side and generate electrical energy from a temperature difference via the Seebeck effect. Furthermore, the invention relates to thermoelectric generators with thermoelectric elements made of functionally graded materials and manufactured by additive manufacturing, in particular by three-dimensional printing. This structure allows the electrical and thermal material properties within the thermoelectric elements to be selectively varied along the direction of heat flow.The invention is particularly applicable in systems for the utilization of waste heat, for example in industrial plants, vehicles, electronic devices, energy-autonomous sensor systems and in mobile or stationary energy supply facilities. State of the art

[0002] Thermoelectric generators are devices for the direct conversion of a temperature difference into electrical energy based on the Seebeck effect. Such generators are used particularly for the utilization of waste heat in industrial plants, vehicle engines, electronic devices, and autonomous power supply systems.

[0003] Common thermoelectric generators typically consist of a multitude of thermoelectric elements made from p-type and n-type semiconductor materials, arranged between a hot and a cold side. Typical materials for such thermoelectric elements include bismuth telluride, lead telluride, skutterudite, and half-Heusler alloys.

[0004] In conventional thermoelectric modules, the thermoelectric leads generally have a homogeneous material composition along their entire length. However, this homogeneous structure leads to several technical limitations. Since a temperature gradient exists along the length of a thermoelectric element, it would be advantageous if the material properties could be locally adapted to the respective temperature ranges. With homogeneous materials, however, such adaptation is only possible to a limited extent.

[0005] Another problem is that thermomechanical stresses often occur between different material layers and contact structures in known thermoelectric generators. These stresses arise particularly during repeated heating and cooling cycles and can lead to material fatigue, microcracks, or contact degradation, thereby impairing the efficiency and lifespan of the generators.

[0006] Furthermore, many well-known manufacturing processes for thermoelectric modules are based on sintering processes, machining, or conventional manufacturing techniques, which only allow for limited precise spatial variation of the material composition within a single thermoelectric element. The production of functionally graded structures with such methods is often complex, costly, or only achievable with several separate manufacturing steps.

[0007] Approaches to improving thermoelectric performance through doping, nanostructuring, or multilayer materials have already been proposed in the scientific literature. Nevertheless, the fabrication of thermoelectric elements with continuously varying material properties along their length remains technically challenging and often only reproducible to a limited extent.

[0008] Furthermore, conventional manufacturing processes offer only limited possibilities for realizing complex geometric structures within the thermoelectric elements, which could be advantageous for targeted control of heat flow and electrical transport properties.

[0009] Against this background, there remains a need for thermoelectric generators in which the material properties of the thermoelectric elements can be specifically adapted along the temperature gradient, while simultaneously enabling flexible and efficient manufacturing of such structures. Object of the invention

[0010] The present invention is based on the objective of providing a thermoelectric generator that enables improved conversion of temperature differences into electrical energy while simultaneously reducing structural disadvantages of conventional thermoelectric generators.

[0011] In particular, a thermoelectric generator should be provided in which the material properties of the thermoelectric elements can be specifically adapted along the temperature gradient in order to improve the efficiency of the thermoelectric energy conversion.

[0012] Furthermore, a design should be created that reduces thermomechanical stresses within the thermoelectric elements, thereby enabling higher structural stability and an improved service life of the generator under repeated thermal loads.

[0013] Furthermore, a thermoelectric generator will be provided whose thermoelectric elements can be manufactured using additive manufacturing, thus enabling flexible production of complex material structures as well as targeted variation of the material composition within the thermoelectric elements. Summary of the invention

[0014] The present invention relates to a thermoelectric generator for converting a temperature gradient into electrical energy. The generator comprises a plurality of thermoelectric elements arranged between a hot side and a cold side. The thermoelectric elements consist of functionally graded materials whose material composition varies continuously or stepwise along the direction of heat flow.

[0015] The thermoelectric elements are preferably manufactured using additive manufacturing, in particular by three-dimensional printing, which allows for targeted spatial variation of the material composition and doping within the elements. The graded material structure creates a gradient in electrical conductivity, thermal conductivity, and Seebeck coefficient along the thermoelectric elements.

[0016] The structure according to the invention enables improved adaptation of the material properties to the local temperature conditions, reduces thermomechanical stresses and improves the efficiency of thermoelectric energy conversion. Detailed description of the invention

[0017] The present invention provides a thermoelectric generator designed to convert a temperature gradient into electrical energy. The generator comprises a plurality of thermoelectric elements arranged between a hot side and a cold side, which generate electrical energy through the Seebeck effect.

[0018] In contrast to conventional thermoelectric generators, in which the thermoelectric elements consist of homogeneous materials, the thermoelectric elements according to the present invention are constructed from functionally graded materials. The material composition within the thermoelectric elements is changed continuously or stepwise along the direction of heat flow.

[0019] The thermoelectric elements are preferably manufactured using additive manufacturing, in particular by three-dimensional printing. Additive manufacturing allows for the targeted variation of material composition, doping concentration, and structural properties within the thermoelectric elements. This results in a graded material structure in which the electrical and thermal material properties can be adapted along the temperature gradient.

[0020] The use of functionally graded materials allows for improved adaptation of local material properties to the respective temperature ranges within the thermoelectric generator. Simultaneously, thermomechanical stresses between different material regions can be reduced, as the transitions between material properties are not abrupt but continuous.

[0021] Furthermore, additive manufacturing enables the production of complex internal geometries within thermoelectric elements. Such microstructured geometries can selectively influence heat flow and electrical transport, thereby improving thermoelectric energy conversion.

[0022] The thermoelectric generator according to the invention thus exhibits an improved adaptability of the material properties along the temperature gradient and enables a more efficient use of temperature differences for electrical energy generation.

[0023] The thermoelectric generator according to the invention comprises thermoelectric elements made of functionally graded materials, which are produced by additive manufacturing, in particular three-dimensional printing. The material composition within the thermoelectric elements is varied continuously or stepwise along the direction of heat flow.

[0024] This graded material structure creates a spatial gradient of electrical conductivity, thermal conductivity, and Seebeck coefficient within the thermoelectric elements. This allows the local material properties to be specifically adapted to the respective temperature ranges within the thermoelectric generator.

[0025] Additive manufacturing makes it possible to apply different material compositions layer by layer, thus creating a controlled material gradient structure within a single thermoelectric element. In this way, doping concentrations, material proportions, or structural properties can be precisely varied.

[0026] A further advantage of the solution according to the invention is that the graded material structure reduces thermal stresses between adjacent material layers, since transitions between different material properties are not abrupt but continuous. This improves the mechanical stability of the generator and increases its service life under repeated thermal loads.

[0027] Furthermore, the use of additive manufacturing technologies enables the production of complex geometric structures within thermoelectric elements. In particular, microstructured internal geometries can be created that selectively influence heat flow and electrical transport, thereby improving thermoelectric energy conversion.

[0028] By combining functionally graded materials and additive manufacturing, a thermoelectric generator is provided that enables improved adaptation of material properties along the temperature gradient, reduces thermomechanical stresses and achieves increased efficiency of thermoelectric energy conversion.

[0029] The present invention relates to a thermoelectric generator for converting a temperature gradient into electrical energy. Thermoelectric generators are used in numerous applications, in particular for utilizing waste heat in industrial processes, vehicles, electronic devices, and energy-autonomous sensor systems.

[0030] Common thermoelectric generators are generally based on thermoelectric elements made of homogeneous semiconductor materials such as bismuth telluride, lead telluride, or related alloys. These materials are typically manufactured in the form of solid p-type and n-type leads and positioned between two temperature surfaces.

[0031] A major problem with conventional thermoelectric generators is that the materials used have a uniform material composition along the entire length of the thermoelectric elements. This results in several technical disadvantages.

[0032] Firstly, thermomechanical stresses occur between different material layers and contact surfaces along thermoelectric elements due to temperature gradients, which can lead to structural degradation and reduced lifetimes. Secondly, the electrical and thermal material properties cannot be optimally matched along the temperature gradient, thus limiting the thermoelectric conversion efficiency.

[0033] Furthermore, conventional manufacturing processes for thermoelectric modules are often limited to sinter-based or mechanical manufacturing processes, which only allow for a limited targeted spatial variation of the material composition within a single thermoelectric element.

[0034] Against this background, the technical object of the present invention is to provide a thermoelectric generator that enables improved adaptation of the material properties along the temperature gradient, reduces thermomechanical stresses and at the same time allows for more efficient energy conversion.

[0035] In particular, a structure should be provided in which the material composition within the thermoelectric elements can be specifically changed without relying on complex multi-stage manufacturing processes.

Claims

[1] Thermoelectric generator for converting a temperature gradient into electrical energy, comprising a plurality of thermoelectric elements arranged between a hot-side interface and a cold-side interface, characterized by that the thermoelectric elements are manufactured using additive manufacturing by three-dimensional printing and consist of functionally graded materials, the material composition of which varies continuously or stepwise along a heat flow direction, so that a gradient of electrical conductivity, thermal conductivity and Seebeck coefficient is generated within the thermoelectric elements. [2] Thermoelectric generator according to claim 1, characterized by, that the functionally graded materials have a spatially varying doping or material composition within the thermoelectric elements, thereby adapting the local thermoelectric properties along the temperature gradient. [3] Thermoelectric generator according to claim 1 or 2, characterized by , that the thermoelectric elements comprise p-conducting and n-conducting legs arranged in an electrically serial and thermally parallel configuration, each possessing a graded material structure along its length. [4] Thermoelectric generator according to any one of the preceding claims, characterized by that the additively manufactured thermoelectric elements have microstructured internal geometries designed to control heat flow and improve thermoelectric energy conversion. [5] Thermoelectric generator according to any one of the preceding claims, characterized by that the thermoelectric elements are arranged in a modular generator structure, with several graded thermoelectric elements electrically interconnected to enable scalable energy generation from temperature gradients.