Elasto-thermoelectric non-linear, fully coupled, and dynamic finite element analysis of pulsed thermoelectrics. (25th August 2016)

• Record Type: Journal Article
• Authors: Pérez-Aparicio, J.L.; Palma, R.; Moreno-Navarro, P.
• Is Part Of: Applied thermal engineering. Volume 107(2016:Aug.)
• Page Start: 398
• Page End: 409
• Publication Date: 2016-08-25
• Subjects: Pulsed thermoelectric materials -- Joule, Peltier, Thomson -- Thermal stresses -- Dynamic analytical solution -- Optimal intensity -- Stress distributions; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2016.05.114
• Languages: English
• ISSNs: 1359-4311

Abstract

Highlights: High pulse gains cannot be applied: limits in reachable overcooling and stress. Non-thermoelectric parts are fundamental for thermal dynamics, stress calculations. Stress distributions are complex, tend to concentrate in corners at all instants. Max stresses occur at end of pulse and predominant component is the vertical. A pulse threshold variable with TE length exists so that any time can be applied. Abstract: This paper presents a numerical study on the influence of pulsed electric signals applied to the overcooling of thermoelectric devices. To this end, an experimental setup taken from the literature and a commercial cell are simulated using a complete, specially developed research finite element code. The electro-thermal coupling is extended to include the elastic field, demonstrating that the increment of cooling can produce mechanical failure. Numerical results are developed and the variation of overcooling versus pulse gain and versus duration is validated towards a new analytical expression and the experimental data. The issue of optimal intensity at steady-state is also newly developed. Thermal and mechanical trends are presented using constant and variable (with temperature) material properties for a single thermoelement. While some of the first trends are similar to those of published works, others are different or directly new, all closer to those of the experiments. The mechanical results have not been thoroughly studied until recently. The three-dimensional finite element mesh includes non-thermoelectric materials that are fundamental for the current study. Distribution of stresses during steady and transient states are shown inside the thermoelement, for five components and for the combined Tresca stress. Concentrations at corners of the lower side appear close to the cold face. Due to these concentrations, 27-node isoparametric, quadratic brick elements are used. It is shown that the mechanical field is an important factor in the design of pulsed thermoelectrics, since for practical applications the stress levels are close or slightly above the admissible limits.