Thermal performance and COP assessment of thermoelectric coolers using gallium and paraffin waxes as phase change materials under different pulsation durations: a comparative study
摘要
The Coefficients of Performance (COP) of thermoelectric cooler (TEC ) devices are highly affected by temperature differences. The insufficient cooling of these devices leads to heat accumulation at the hot side of the TEC devices. This leads to increased temperature differences and a decrease in COP values. However, Phase Change Materials (PCMs) have proven as a good choice in controlling the temperatures in thermal management applications. Hereby, the current study proposed the integration of high-conductivity PCMs as thermal buffers for TEC devices. We intended to investigate the thermal performance of PCM-based TEC devices under different durations of pulsation loads. The study compares the performance of a high-conductive liquid metal (Gallium) with a traditional organic paraffin (OM32) using the FEA method via COMSOL Multiphysics v6.3 software. The tested cases were composed of Bi2Te3-based TEC devices subjected to varying current pulse durations (4, 6, and 8 s) and different PCM fill heights (1.5 mm and 3 mm). The simulation results showed a superiority of gallium over OM32. A nearly isothermal hot-side temperature of the TEC devices was achieved through using gallium as PCM. Also, gallium prevented thermal spikes during current pulses due to its high thermal conductivity and its large volumetric latent heat capacity. On the other hand, when OM32 was used as a PCM in the TEC system, large temperature gradients were built due to its limited thermal conductivity. The recorded cold-side temperatures of the TEC system based on gallium were 2 to 5 K lower than the OM32 system. During the initial operation of the TEC device, gallium was able to maintain a high COP value during the steady current input. However, no noticeable difference in COP value was detected for both PCMs during the pulsation duration. But, after the pulsation duration, the OM32 system recorded a COP value higher than the gallium system by 0.1. Also, an improved COP value of gallium cases was maintained for about three times the duration compared to OM32 cases. The study shows that the TEC performance can be enhanced during the pulsation loads when gallium is used. These observations suggest that gallium can offer a compact and efficient solution for improving the TEC performance.