Flow boiling heat transfer coefficient and pressure drop in minichannels with artificial activation cavities by direct metal laser sintering

Abstract

In the present paper, flow boiling heat transfer characteristics of minichannel heat sinks with and without artificial activation cavities by Direct Metal Laser Sintering (DMLS) are experimentally investigated. Scanning Electron Micrograph (SEM) is used to characterize the heat sinks and found that artificial activation cavities can be effectively manufactured by DMLS. Flow visualization was performed using a high-speed video camera and found that a series of columnar bubbles were appeared at higher frequencies in the heat sinks with artificial activation cavity in comparison with heat sink without artificial activation cavities. And the average heat transfer coefficients of DMLS-2#, DMLS-3#, DMLS-4#, DMLS-5# (minichannel with artificial activation cavities) are 2.62, 2.27, 2.03, 2.34 times that of DMLS-1# (minichannel without artificial activation cavities) under the same conditions, respectively. The pressure drop for different heat sinks increases with the heat flux increasing at low heat flux conditions, and the pressure fluctuated intensively at high heat flux conditions. Meanwhile, Double Factors Variance Analysis is introduced to analyze the influence of the design parameters on heat transfer. Overall, artificial activation cavities qualitatively designed for enhancing heat transfer in minichannel heat sink by DMLS have achieved the expectation results.