EFFECTS OF CARBON NANOTUBE ARRAY PATTERNING ON NUCLEATE POOL BOILING
Advances in integrated circuit technology have recently been constrained by the absence of suitable, reliable and cost effective cooling solutions. The past two decades has seen significant research on pool boiling as a potential electronic cooling solution. Pool boiling is an attractive cooling option because of its unique combination of passive fluid circulation and high heat flux capability. Recent studies have shown that the introduction of carbon nanotube (CNT) arrays on a silicon surface considerably improves pool boiling heat transfer. The present experimental work considers the introduction of CNT arrays in various patterns on a chip surface. The aim is to determine the effects of array spacing on nucleate pool boiling using FC-72 (3M coolant) as working fluid. Multi-walled CNT arrays were grown on silicon substrates in various patterns using a plasma enhanced chemical vapor deposition (PECVD) system. Pool boiling curves were measured for a CNT grid pattern with 60% surface coverage and a CNT island pattern with 5% surface coverage on a silicon substrate. Key performance parameters for these surfaces were incipience superheat, nucleate boiling heat transfer coefficient, and critical heat flux (CHF). These characteristics are compared to previous results for bare silicon and a fully coated CNT surface. The results reveal that boiling heat transfer enhancement is a function of CNT surface coverage. Optimum enhancement is achieved with a fully coated silicon surface.