Instability control of two-phase flow in microchannel heat exchangers

Due to the integration and miniaturization of electronic components, the cooling requirement of microelectronic devices increases rapidly. The microchannel heat sink has been widely considered as one of the most promising solutions to meet cooling demand due to its advantages of high surface area-to-volume ratio, large convective heat transfer coefficient (HTC), and compact structure compared with a macrochannel one. Compared with a single-phase liquid flow, flow boiling in microchannel heat sinks has advantages of higher HTC, lower coolant flow rate, and more uniform wall temperature, which makes flow boiling in microchannels promising to meet the heat dissipation requirement in many fields, including aerospace, microelectronics, advanced energy and power systems, etc. However, the instability of the two-phase flow in the microchannel heat exchanger becomes the most important obstacle for its application. To solve this fundamental problem, different methods were carried out and reported. All of the cutting-edge control technologies in this field are reviewed in this chapter. These methods were compared and discussed, with research trends summarized. Finally, as an example, an experimental study on the instability of two-phase flow in a microchannel heat exchanger was reported.