Effects of thermal and electrical contact resistances on the performance of a multi-couple thermoelectric cooler with non-ideal heat dissipation

•A 3D finite element model is built for commercial bismuth telluride thermoelectric coolers (TECs).•The influence of adverse working conditions on the cooling performance of TECs is studied quantitatively.•Of all adverse factors, electrical contact resistance may cause the most severe reduction in a TEC's performance.•A phenomenon of drift of optimal current in a TEC under adverse working condition is found and discussed. The influence of adverse working conditions on the cooling performance of thermoelectric cooling chips is numerically studied in this work. A three-dimensional steady-state physical and mathematical model that considers thermoelectric coupling is developed for a commercial thermoelectric cooler (TEC) of bismuth telluride (Bi2Te3). An imaginary non-uniform temperature distribution with the variable maximum excess temperature (θm) and scale of high temperature region (ω) are used as boundary conditions for the hot end of the chip to simulate the effect of a poor heat dissipation. The electrical contact resistance Re,c (=M×re,c) and the thermal contact resistance Rk,c (=N×rk,c) are set at the interface layer of different materials with two magnifying factors (M and N) to simulate varying degrees of interfacial effects from defective contacts. The numerical results show that of all adverse factors, electrical contact resistance may cause the most severe reduction in a TEC's performance. Further studies demonstrated that M has a far greater effect on the performance curve (Qcvs.I and COPvs.I) than the other three parameters (N, θm, ω) in both Qcmax and COPmax modes. In addition, the phenomenon of drift of the optimal current is found and discussed.