Layer-deepened current harmonized improvement method: An optimal electrical array configuration method for performance optimization of a thermoelectric generator

Under most operating conditions, thermoelectric generators (TEGs) produce less than the required output power, primarily due to the mismatch loss caused by the variations in the temperature differences across individual thermoelectric modules (TEMs). One effective method for reducing mismatch loss is to connect the TEMs such that each TEM can operate with a near-optimal electrical current. In this study, we propose, for the first time, the layer-deepened current harmonized improvement method (deep-CHIME) to address the mismatch loss issue in TEGs. This approach effectively reduces mismatch losses by finely adjusting the electrical currents induced in the individual TEMs to their ideal values. A theoretical model was developed by combining the thermoelectric equations and Kirchhoff's voltage and current laws to determine the optimal values of the major design parameters, namely the ratio of the electrical branches and ratio of the number of TEMs, to form the deep-CHIME configuration. Furthermore, the effect of deep-CHIME on the output power performance was substantiated by using an experimentally validated numerical model that accurately captured the thermoelectric energy conversion phenomena, including heat pumping and Joule heating. Module-by-module analyses indicated that the current flowing through each TEM approached its ideal value as the layer of the CHIME configuration deepened. Numerical results showed that a TEG with TEMs electrically connected according to a four-layer deep-CHIME configuration produced up to ∼99 % of the ideal output power, exhibiting less than 1 % mismatch loss under various engine operating conditions. Moreover, the four-layer deep-CHIME configuration improved the output power and conversion efficiency by 17.6 % and 18.4 %, respectively, compared to a conventional parallel configuration.