Boiling time effect on CHF enhancement in pool boiling of nanofluids

A comprehensive review on pool boiling of nanofluids

“…Okawa et al [75] investigated the boiling time effects on boiling heat transfer for TiO 2 /water nanofluids on the upper part of a copper block, which was mounted to the bottom of the SS test vessel (Ø160x200mm). The experimental results showed that the boiling heat transfer first decreased, then increased, and finally reached an equilibrium situation.…”

“…A possible reason for the deterioration of the boiling HTC is the increased thermal resistance between the heating surface and fluid, but this effect can be negligible because the oxide nanoparticles such as alumina, titania and silica have thermal conductivities at several orders of magnitude lower than that of the heating material [39,43,65]. Another reason for this deterioration can be attributed to a decrease in active nucleation site density caused by the decrease in contact angle (θ) between the fluid and heater surface, as observed in several studies [54,75,85]. This effect can be explained in the following equation suggested by Wang and Dhir [103]: 6 (2)…”

“…Besides, at the high particle concentrations, the surface structure can completely vary due to the nanoparticles deposition. Therefore, an increase in the surface roughness can be contributed to the generation of new nucleation cavities and the enhancement of the boiling HTC [75].…”

Boiling Heat Transfer Characteristics of Nanofluids

“…Photos of hated surface (a) before and (b) after the nucleate boiling in TiO2-water nanofluid for 3 minutes [27].…”

“…0*+9:78C&@642789 7Ö0 9\78ABó x789CD} ÞE5FGH/Na93aba`p¡' "$1 9789ìí7/CD0EÞ*0N`9 78C& 9ab0`3I02J S¤0c f 134K0Ra93789L¹# ìaeMNO;P5±b88 9 a cd 5H bS¤0QRóô078\bp¡¬ae1W b010Sb Fig. 6 Dependence of the CHF enhancement of nanoparticle-coated surface on the product of particle concentration and boiling time [27]. …”