Pool Boiling Amelioration by Aqueous Dispersion of Silica Nanoparticles

Abstract

Non-metallic oxide nanofluids have recently attracted interest in pool boiling heat transfer (PBHT) studies. Research work on carbon and silica-based nanofluids is now being reported frequently by scholars. The majority of these research studies showed improvement in PBHT performance. The present study reports an investigation on the PBHT characteristics and performance of water-based silica nanofluids in the nucleate boiling region. Sonication-aided stable silica nanofluids with 0.0001, 0.001, 0.01, and 0.1 particle concentrations were prepared. The stability of nanofluids was detected and confirmed via visible light absorbance and zeta potential analyses. The PBHT performance of nanofluids was examined in a customized boiling pool with a flat heating surface. The boiling characteristics, pool boiling heat transfer coefficient (PBHTC), and critical heat flux (CHF) were analyzed. The effects of surface wettability, contact angle, and surface roughness on heat transfer performance were investigated. Bubble diameter and bubble departure frequency were estimated using experimental results. PBHTC and CHF of water have shown an increase due to the nanoparticle inclusion, where they have reached a maximum improvement of ≈1.33 times over that of the base fluid. The surface wettability of nanofluids was also enhanced due to a decrease in boiling surface contact angle from 74.1° to 48.5°. The roughness of the boiling surface was reduced up to 1.5 times compared to the base fluid, which was due to the nanoparticle deposition on the boiling surface. Such deposition reduces the active nucleation sites and increases the thermal resistance between the boiling surface and bulk fluid layer. The presence of the dispersed nanoparticles caused a lower bubble departure frequency by 2.17% and an increase in bubble diameter by 4.48%, which vigorously affects the pool boiling performance.

The Pool-Boiling-Induced Deposition of Nanoparticles as the Transient Game Changer—A Review

“…An excessive nanoparticle deposition may cause the thickening of the deposition layer, which in turn, may lead to an increase in the thermal resistance and, consequently, to the pool-boiling heat-transfer deterioration. This fact was confirmed through the experimental work conducted by the researchers Mukherjee et al [ 88 ] using silica nanofluids having different volume fractions. The authors reported that with lower concentrations of 0.0001 vol.…”

A Meta-Analysis Review: Nanoparticles as a Gateway to Optimized Boiling Surfaces

“…Other experiments [ 10 , 63 , 69 , 70 , 71 ] observed a change in the typical boiling performance of water when using nanoparticle suspensions, attributed to the deposition of nanoparticles on the heated surface forming a porous layer. The deposited porous layer was found in some cases [ 69 , 70 ] to enhance the HTC until a certain concentration of nanoparticles, and then degrade it. At low concentrations, a small amount of deposition led to an increased bubble emission frequency by providing additional nucleation sites [ 69 , 72 ].…”

Effect of Multi-Walled Carbon Nanotubes-Based Nanofluids on Marine Gas Turbine Intercooler Performance

“…Moreover, the obtained thermophysical properties were later used in the mathematical modelling of the intercooler. In terms of the physical stability of the as-prepared dispersions, it was visually determined using the photographic image capturing method [ 18 , 30 ] directly after the preparation of the nanofluids and up to 45 days.…”