Transient Characteristics of Pool Boiling Heat Transfer in Nanofluids

Abstract

This study shows the transient characteristics of the pool boiling curves using nanofluid as the boiling fluid. This time-dependency is in sharp contrast to a unique steady-state pool boiling curve that is typically obtained for a pure fluid. Past researches on nanofluids have provided several interesting information about the thermal characteristics for this potentially promising cooling fluid. Results from these studies have shown some extraordinary critical heat flux (CHF) values and thermal conductivity enhancement that is yet to be explained by existing theories and correlations. The nature of the pool boiling curve for a nanofluid is dependent on the nanoparticle concentration in the base fluid. Higher concentration nanofluids show a perceptible degradation in the boiling heat transfer coefficient but have exhibited an enhanced CHF value (up to ∼80%) when compared to the CHF value of the base fluid (water). Another key observation has been in the significant deposition of nanoparticles on the heater surface. This fouling of the heater surface by nanoparticles is widely viewed as a main contributor that modifies the pool boiling curve of the base liquid. The deposition of the nanoparticles on the heater surface is dynamic and this in turn makes the nanofluid pool boiling curve exhibit transient characteristics.