Characteristics of bubble behavior and enhanced heat transfer of nanofluid in microchannels under electric and magnetic co-excitation

Nanofluid boiling heat transfer in microchannels has the advantages of small size and high heat transfer efficiency, and can meet the requirements of large heat load and high structural integration. In this paper, the enhanced heat transfer characteristics experiment of nanofluids under electro-magnetic co-excitation were studied on a microchannel boiling flow experimental platform. The generation, deformation and motion mechanism of bubbles in nanofluids under electro-magnetic co-excitation were studied by high-speed photography and numerical simulation, achieving microscopic visualization of nanofluids. The experiment shows that the small bubbles are affected by the electric field force and pass through the electrode wire, and perform regular lateral reciprocating motion between the two sides of the wall. This motion of the bubbles can not only strengthen the orderly disturbance inside the fluid, but also will not disrupt the heat transfer mechanism between various media, making the heat transfer enhancement and not chaotic. Magnetic excitation causes the nanoparticles to form a magnetic coupling structure along the direction of the magnetic field, the average strengthening effect increased to 29%. When the current is applied and the electromagnetic coupling field is formed, the heat transfer effect is improved by 36%.