A multi-process coupling study of secondary injection effect on combustion characteristics of a vibration thermoelectric combustor

This paper presents an unconventional type of energy converter referred to as a vibrating thermoelectric combustor. The vibrating thermoelectric combustor harnesses mechanical vibrations to directly convert the thermal energy generated from fuel combustion into electrical energy. Additionally, this study investigates the influence of a secondary injection strategy on the combustion of gasoline vibrating thermoelectric combustors. However, due to the unconventional thermoelectric coupling and vibration, traditional methods for simulating combustion present significant challenges. Therefore, this study proposes a novel multidimensional coupled model that incorporates motion, mixing, and combustion while utilizing iterative algorithms for solving the model. The results demonstrate that the fluctuation of the secondary injection proportion affects the vibration of the vibrational thermoelectric combustor, compression ratio, thereby altering the vibration speed, and initial conditions for combustion initiation. Under the condition of a secondary injection proportion of 9:1, the equivalent rotational speed of the vibrational thermoelectric combustor is 2473 rpm, the compression ratio is 8.75, the combustion efficiency is 95.4 %, and the thermal efficiency is 41.0 %. When the secondary injection proportion is adjusted to 1:9, they are respectively adjusted to 2226 rpm, 7.96, 89.0 %, and 35.0 %. Moreover, an excessively secondary injection proportion hampers the full combustion process.