Modelling a Segmented Skutterudite-Based Thermoelectric Generator to Achieve Maximum Conversion Efficiency

Experimental and Theoretical Investigation of the Effect of Filler Material on the Performance of Flexible and Rigid Thermoelectric Generators

Thermoelectric generators have found many applications where the heat source can be either flat or curved. For a curved heat source, flexible thermoelectric generators are generally used. A filler material with low thermal conductivity can provide additional mechanical support to the thermoelectric module and can reduce convection and radiation losses. Herein, the effect of three different filler materials on the output performance of rigid and flexible thermoelectric generators is investigated. At first, theoretical models are derived and the experimental study validated the models. The experimental study revealed that the flexible thermoelectric modules outperformed the rigid modules; this is due to the reduction of the number of thermal junctions in the flexible modules and due to the differences in the thermal conductivities of the flexible and rigid substrates. Likewise, among TE modules without filler/with air between the TE legs, with polyurethane foam filler material, and with polydimethylsiloxane filler material, air has the lowest thermal conductivity, and therefore, the thermoelectric generator without filler generates higher output power and higher power density than when the other two filler materials are used. For the fixed temperature gradient, the highest power densities for the flexible and rigid thermoelectric generators without filler are 155 and 137.7 μW/cm² for temperature gradients of 10.8 and 10.3 °C, respectively.

A Similarity Model of the Cooling Process of Fluids during Transportation

This article presents a description of a novel method for the identification of a decrease in the temperature of a liquid medium transported by railroad tank cars. No exact analytical solution exists for this phenomenon; therefore, the authors of this article have prepared a mathematical expression for the cooling process of the transported fluid by applying a dimensional analysis, which facilitated the identification of the dimensionless criteria using the relevant dimensional parameters. A functional dependence between the criteria can be identified through a physical or numerical experiment. In this case, a database of the results from a detailed numerical model was used; however, its disadvantage is that the calculation takes much longer than in a simpler similarity model. The output of the similarity model was a function of the average temperature of the fluid at a time applicable to various alternatives in the geometrical, physical, and boundary conditions. The standard deviation of the difference between the temperatures predicted by the similarity model and those calculated by the numerical simulation Tmod − Tsim represented 4.8% relative to the simulated fluid temperature.

Analysis of the Experimental Integration of Thermoelectric Generators in Photovoltaic–Thermal Hybrid Panels

Photovoltaic–thermal panels (PVT) have been widely studied in the last years and have proved to be a technically viable and profitable solution. This work analyses the integration of a set of thermoelectric generators (TEG) inside these panels in order to obtain additional power. The thermoelectric material takes advantage of the temperature gap between the hottest part of the system, the output flow from the collector, and the cold water feeding the solar system. An experimental test bench with a PVT having integrated TEGs and the same PVT in parallel without TEGs was mounted to compare both devices. The corresponding CFD simulation was also carried out to better understand the temperature map in the arrangement. Both experimental and computational results show that the manufacture of the panel with integrated TEGs should be carefully studied before becoming a commercial product. They also gave some guidelines for the improvement of the prototype in this integrated product.