Estimating thermal efficiency of a self-developed capacitor discharge welding equipment through nonlinear function specification method

Abstract

This study presents a thermal analysis using a self-developed capacitor discharge welding equipment. The addressed process involves a rapid welding of the hot junction of a K-type thermocouple wire. Precise energy input must be provided to achieve an effective junction. The procedure involves solving a three-dimensional nonlinear transient heat transfer equation including phase change, facilitated by COMSOL Multiphysics® software. The Iterative Function Specification Method is employed to estimate the heat rate, solving this inverse heat conduction problem. Experiments were conducted to gather temperature data at 90 ms intervals from accessible regions within the domain. Furthermore, the elemental identification of the k-type thermocouple was accomplished using Scanning Electron Microscopy. The utilization of two thermocouples is instrumental in improving data quality and mitigating measurement uncertainties due to the problem complexity. The efficiency of the welding process is evaluated by determining the energy stored within the capacitor bank, resulting in 30%. The low efficiency is partly attributed to energy losses through light and noise. Results show close alignment between experimental data and numerical temperature. This study not only provides insights into rapid welding processes but also holds potential for various approaches within this field.