Multi-Physic Coupling Analysis and Structure Optimization of Vehicle Thermoelectric Refrigerators

In vehicle-mounted thermoelectric refrigerators, limited installation space and fluctuating ambient conditions make it difficult to achieve both sufficient cooling capacity and low power consumption. However, most previous studies have focused on thermoelectric materials or standalone devices rather than system-level optimization under realistic vehicle constraints. To address this issue, a three-dimensional multiphysics-coupled finite element model combined with a parametric optimization approach was developed for a vehicle-mounted thermoelectric refrigerator used in one of Dongfeng Motor’s new energy vehicle models. Based on this model, the effects of key geometric parameters, including thermoelectric leg height (l), leg width (w), and leg number (pd), as well as operating conditions, namely input voltage (U) and ambient temperature (Ta), on the overall performance of the refrigerator, including cooling capacity (Qc), coefficient of performance (COP), and interior center temperature (T), were systematically investigated. The results show that under nominal operating conditions (U = 13.5 V, Ta = 25 °C), increasing pd from low to moderate values significantly improves cooling capacity, reduces the interior temperature, and decreases power consumption. However, further increases in pd lead to diminishing improvements in cooling performance because of the heat dissipation limitation on the hot side. By comprehensively evaluating cooling performance and energy consumption, the optimal design was determined to have 322 legs, a leg width of 1.4 mm, and a leg height of 1.8 mm. Under these conditions, the refrigerator achieved a cooling capacity of 13.95 W, a power consumption of 38.4 W, a COP of 0.36, and a compartment center temperature of 10.71 °C. Compared with the conventional 254-leg module (w = 1.4 mm, l = 1.6 mm), the optimized design improved the COP by more than 45.1% and reduced power consumption by 28.8%. In addition, the results indicate that under high ambient temperature conditions, the overall system performance is mainly limited by the hot-side heat rejection capacity. Overall, this study provides an effective structural optimization approach for improving the energy efficiency of compact thermoelectric refrigerators in confined spaces and offers a useful reference for the low-power design of vehicle-mounted cooling devices.