Flat Miniature Heat Pipes With Micro Capillary Grooves

Flat miniature heat pipes (FMHP’s) are shown to be very promising in the cooling of electronic component systems. This investigation presents a detailed experimental and theoretical analysis on maximum heat transfer capabilities of two copper-water FMHP’s with diagonal trapezoidal micro capillary grooves and one copper-water FMHP with axial rectangular micro capillary grooves. Maximum heat flux on the evaporator wall of the 120-mm long axial grooved heat pipe, with a vapor channel cross-sectional area of approximately 1.5 × 12 mm² and rectangular grooves of dimensions 0.20 mm wide by 0.42 mm deep, exceeded 90 W/cm² in the horizontal orientation and 150 W/cm² in the vertical orientation. Theoretical prediction of the capillary limitation in the horizontal orientation agreed reasonably well with the experimental data.