Fabrication and thermal performance of porous crack composite wick flattened heat pipe

• This study developed a novel porous crack composite wick flattened heat pipe.
• Phase change flattening technology was proposed to form mode I cracks and fabricate composite wick.
• Start-up performance, isothermal performance, heat transfer limit and thermal resistance were investigated.

A novel porous crack composite wick flattened heat pipe (short for PCHP) was developed for the cooling of micro chips. PCHP was fabricated from grooved-sintered wick cylindrical heat pipe (short for GSHP) by phase change flattening technology. Porous crack composite wick consisted of micro crack channels at the unbending section and porous sintered powder. Micro crack channels were mode I cracks formed during phase change flattening process. Thermal performance of PCHP such as start-up performance, isothermal performance, heat transfer limit and thermal resistance was investigated by experiments. It was found that PCHP was able to achieve its steady state in about 30 s. The maximum temperature difference between evaporation section and condensation section of PCHP was less than 0.5 °C when the input power was about 10 W. The heat transfer limit of PCHP was highest about 50 W at cooling water temperature of 50 °C compared with grooved wick flattened heat pipe (short for GHP) and sintered wick flattened heat pipe (short for SHP). The thermal resistance of PCHP was a medium value between GHP and SHP.