Combined cooling and power: Investigating the coupling effect between a microfluidic fuel cell and a heating chip

Microfluidic fuel cell (MFC) employs microfluidic electrolytes for reactant delivery, which is naturally suitable for combined cooling & power applications such as AI chips. However, this dual function has long been neglected in past literature. This work investigates the coupling effect between a MFC and a heating chip. The integrated system can not only remove the waste heat continuously but also leverage it to enhance electrochemical reactions, thereby improving both cooling efficiency and power output at the same time. To understand the in-depth coupling mechanism, various operation conditions are studied, including different electrolyte flow rates and heating modes. Results indicate that unlike conventional MFCs, the MFC performance under external heating is higher at lower flow rates, which is mainly benefited from the higher electrolyte temperature under this circumstance. For instance, at a constant heating power of 0.15 W/cm² and a flow rate of 100 µL/min, the MFC achieves a peak power density of 27.3 mW/cm², while it is only 16.6 at 1000 µL/min. Nevertheless, higher flow rates lead to better cooling effect, which can lower the chip temperature from 79.4°C to 54.0°C at 1000 µL/min, while it is only to 64.2°C at 100 µL/min. To improve the cooling effect of MFC at lower flow rates, both MFC scaling-up and MFC stacking have been investigated, of which the latter strategy exhibits much better performance in both cooling and power. To sum up, this work provides valuable insights into the design and optimization of microfluidic combined cooling & power system, highlighting its potential in addressing thermal & power challenges of next-generation AI chips.