Simulation Analysis of Tilted Polyhedron-Shaped Thermoelectric Elements

Abstract

The generation of thermoelectricity is considered as a promising approach to harness the waste heat generated in industries, automobiles, gas fields, and other man-made processes. The waste heat can be converted to electricity via a thermoelectric (TE) generator. In this light, the generator performance depends on the geometric configuration of its constituent elements as well as their material properties. Our previous work reported TE behaviors for modules consisting of parallelogram-shaped elements because elements with tilted laminate structures provide increased mechanical stability and efficient heat transferring ability from the hot surface to the cold surface. Here, we study TE elements in the shape of a polyhedron that is obtained by mechanically truncating the edges of a parallelogram element in order to further enhance the generator performance and reduce TE material usage. The TE performance of the modules consisting of these polyhedron elements is numerically simulated by using the finite-volume method. The output power, voltage, and current of the polyhedral TE module are greater than those of the parallelogram-element module. The polyhedron shape positively affects heat transfer and the flow of electric charges in the light of increasing the efficiency of conversion from heat to electricity. By varying the shape of the truncated portions, we determine the optimal shape that enables homogeneous heat flux distribution and slow diffusion of thermal energy to obtain the better efficiency of conversion of heat into electricity. We believe that the findings of our study can significantly contribute to the designing policy in TE generation.

Performance Analysis of Thermoelectric Modules Using Polyhedron Elements

“…the shortest path. 7) Here the length of this fast route is changed with the module configuration. The thermal diffusion in module is therefore largely affected by the length of the path and thus influencing TE performance.…”

Performance Analysis of Thermoelectric Modules Consisting of Square Truncated Pyramid Elements Under Constant Heat Flux

“…Shapes of thermoelectric (TE) elements (1)(2)(3)(4)(5)(6)(7)(8) and interesting structures of TE modules (TEM) (9)(10)(11)(12) based on heat flow analysis have been recently proposed. The traditional Π-type TE elements are sandwiched between two flat substrates with a heat supplier and a heat receiver, and the thermal heat, introduced from the higher temperature side, transfers to the lower temperature side through TE elements.…”

“…Some portions of this transferring heat are converted to electricity in the TE material. In addition to the improvement of the performances of the materials, the optimized TE elements design techniques, using three-dimensional simulations along with simultaneous derivative equations, (4)(5)(6)(7)(8) predict a larger conversion efficiency for the TEM. Varying its length, a segmented TE element was optimized for the best performance (1) .…”

Thermoelectric performance using counter-flowing thermal fluids

“…In essence, TE generation requires a sufficient temperature difference, ∆T, between hot and cold surfaces of TEGs to induce an electromotive force (EMF), and a high ∆T leads to a high EMF, which is attributed to EMF is the sum of the product of the relative Seebeck coefficient and the temperature difference for all p-type and n-type TE elements connected in serial [9], moreover, we had clarified that the homogeneous heat flux throughout a TEG is indispensable to enhance TE performance that is due to the geometry-dependent thermal diffusion becomes uniform [10,11]. Thus as a result, a pair of counter-flowing hot and cold fluids, as shown in Figure 1 (a), should give rise to a better TE conversion on module, where a high ∆T can be facilitated by the hot fluid, and a homogeneous heat flux can be obtained when the hot fluid is cooled and the cold fluid is heated at the same time by exchanging the heat through the conduction of solid TE module in the process of the thermal fluids flow in the opposite, as depicted in Figure 1 This study continued to model a three-dimension (3D) TE module whose surfaces are covered by the counter-flowing hot and cold fluids, and conducted a numerical simulation using finite-volume method in a commercial software environment, Fluent, to clarify the change of module performance with the flow rate of thermal fluids, where fluid dynamics and TE conversion are carried out synchronously, and then the effects of temperature difference and flow rate on TE performance are compared, which illuminates that the regulation of flow rate should be more effective in improving performance of TE module.…”