Influence of hydrogels embedding positions on automatic adaptive cooling of hot spot in fractal microchannel heat sink

To solve the failure of electronic chips caused by local hot spot, the thermoresponsive shrinkage hydrogels are embedded into fractal microchannel heat sink to regulate mass flow rate, which brings more fluid cooling hot spot. The influence of hydrogels embedding positions on adaptive cooling in fractal microchannel heat sink is investigated by numerical simulation. The fractal microchannel heat sink embedded with hydrogels in first and secondary level branch simultaneously (SFMHS 1 + 2) and fractal microchannel heat sink embedded with hydrogels only in first level branch (SFMHS 1) are suitable for dealing with high background heat flux. And the fractal microchannel heat sink embedded with hydrogels in secondary level branch (SFMHS 2) is proper to manage low background heat flux. Moreover, SFMHS 1 + 2 has the highest pumping power, followed by SFMHS 2, while SFMHS 1 consumes the lowest pumping power. When the heat flux of hot spot is 400 W/cm(2) and the background heat flux is 25 W/cm(2), the temperature increment of hot spot in SFMHS 1 and SFMHS 2 are 5.23 K and 3.24 K lower than that of SFMHS 1 + 2, respectively. Besides, SFMHS 1 + 2 still has capability in cooling hot spot when SFMHS 1 cannot detect the hot spot or SFMHS 2 loses its ability in cooling hot spot. That is to say, the fractal microchannel heat sink embedded with hydrogels in first and secondary level branch simultaneously can deal with a wider range of heat flux.