Local heat transfer under an array of micro jet impingement using HFE-7000

Highlights: • Experimental and numerical study of local heat transfer on microscale is reported. • Fourteen 54 µm liquid HFE-7000 jets with standoff distance of 210 µm are used. • Jet Reynolds numbers vary from 162 to 4057 and nominal heat fluxes 10 to 80 W/cm². • Insight into the flow patterns formed due to multiple jet interactions is achieved. • The results agree well with the existing correlations for jet array impingement. -- Abstract: An experimental and numerical study was conducted to elucidate local heat transfer processes under multiple microscale jet impingements using a dielectric coolant, HFE-7000. The micro device used in this experiment was made of a 400-μm thick silicon wafer, a 210-μm thick vinyl sticker, and a 1-mm thick Pyrex substrate. Fourteen jet orifices were etched using deep reactive ion etching (DRIE) on the silicon wafer, and four 100-nm thick resistance temperature detectors (RTDs) and a heater were fabricated from titanium on the Pyrex substrate. The double-sided vinyl sticker was used to bond the layers and to form a micro fluidic channel having dimensions of 1.9 mm × 14.8 mm × 210 μm. Jet Reynolds numbers in the experimental study ranged from 162 to 4057 and nominal heat fluxes ranged from 10 W/cm² to 80 W/cm². A three-dimensional numerical model was developed to predict the jets hydrodynamics and the convection heat transfer coefficients using a turbulent flow model for the turbulent range of the flow. Good agreement was found between the numerical predictions and experiments. The numerical results also provided valuable insight into the flow patterns formed due to multiple jet interactions. Average Nusselt number and pressure drop coefficient values found in the present study correspond well with the existing correlations pertinent to jet array impingement.