# Effect of Nanofluids on Boiling Heat Transfer Performance
## 3 Effects of Nanofluid Physical Properties and Heated Surface on Boiling Heat Transfer
### Effect of Nanoparticles on Boiling Heat Transfer
#### 3.1.1 Effect of Nanoparticle Types on Boiling Heat Transfer
The Zuber correlation curve and the Kindlikar correlation curve are as shown in Equations (4) and (5). \[\mathrm{q}_{\mathrm{max}}=\mathrm{K}_{\mathrm{Z}}\mathrm{h}_{\mathrm{V}}\rho_ {\mathrm{V}}[\frac{\sigma\mathrm{g}(\rho_{1}-\rho_{\mathrm{V}})}{\rho_{ \mathrm{V}}^{2}}]^{0.25}(\frac{\rho_{1}}{\rho_{1}-\rho_{\mathrm{V}}})^{0.5} \tag{4}\]  
\[\mathrm{q}_{\mathrm{max}}=\mathrm{h}_{\mathrm{IV}}\rho_{\mathrm{V}}^{0.5}[ \frac{1+\cos\beta}{16}][\frac{2}{\pi}+\frac{\pi}{4}(1+\cos\beta)\cos\phi]^{0. 5}[\sigma\mathrm{g}(\rho_{1}-\rho_{\mathrm{V}})]^{0.25} \tag{5}\]  
where \(\mathrm{q}_{\mathrm{max}}\) is the maximum heat flux, \(\mathrm{h}_{\mathrm{IV}}\) is the latent heat of vaporization, \(\rho\) is the density, \(\sigma\) is the surface tension, \(\mathrm{g}\) is the acceleration of gravity, and the subscripts \(\mathrm{l}\) and \(\mathrm{v}\) represent liquid and vapor, respectively; \(\mathrm{K}_{\mathrm{Z}}\) is the empirical constant (\(0.12\leq\mathrm{K}_{\mathrm{Z}}\leq 0.16\)). [PERSON] [110] predicted the CHF of pure liquid saturated pool boiling, taking into account fluid dynamics and nonfluid dynamic effects. \(\beta\) is the power receding contact angle and \(\phi\) is the heating surface inclination angle. The experimentally obtained CHF value, [PERSON] predicted value, [PERSON] predicted value, and the deviation between them are shown in Table 2.  
As can be seen from Table 2, the CHF of the coating formed on the heated surface after boiling on the deionized water is higher than the CHF of the nanofluid on the smooth surface, and because the separation of the nanoparticle layer is enhanced, the critical heat \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Experimental** & **Working Fluid** & \begin{tabular}{c} **CHF** \\ **(kW/m2)** \\ \end{tabular} & \
\begin{tabular}{c} **Zuber (Kw/m2)** \\ \end{tabular} &
\begin{tabular}{c} **Kandlikar** \\ **(kW/m2)** \\ \end{tabular} \\ \hline
1 & Distilled water & 1200 & 1108(\(-\)8\%) & 1205(\(+\)0.4\%) \\
2 & Fe\({}_{2}\)O\({}_{3}\)–Water & 1514 & 1108(\(-\)36\%) & 1507(\(-\)0.4\%) \\
3 & Al\({}_{2}\)O\({}_{3}\)–Water & 1542 & 1108(\(-\)39\%) & 1507(\(-\)2\%) \\
4 & CNTs–Water (0.02\%) & 1552 & 1108(\(-\)40\%) & 1507(\(-\)3\%) \\
5 & CNTs–Water (0.1\%) & 1496 & 1108(\(-\)35\%) & 1507(\(+\)0.7\%) \\
6 & Distilled water/layers of Fe\({}_{2}\)O\({}_{3}\) & 1526 & 1108(\(-\)37\%) & 1507(\(-\)1\%) \\
7 & Distilled water/layers of Al\({}_{2}\)O\({}_{3}\) & 1652 & 1108(\(-\)49\%) & 1507(\(-\)9\%) \\
8 & Distilled water/layers of CNTs & 1612 & 1108(\(-\)45\%) & 1507(\(-\)7\%) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Predictions of CHF obtained using Zuber [109] and Kandlikar [110] correlations [76]. Figure 6: Field-emission scanning electron microscopy (FESEM) pictures of applied nanoparticles, (a) ZnO; (b) Al\({}_{2}\)O\({}_{3}\), and SEM of (c) carbon nanotubes (CNTs) [80]. [PERSON] [108] and others studied the boiling heat transfer of water-based Al\({}_{2}\)O\({}_{3}\) and RGO (reduced graphene oxide) nanofluids. The volume concentration ratio of alumina nanoparticles to reduced graphene oxide was 1:1 and the solution volume concentration was 0.001%. The experimental results show that the enhancement of the critical heat flux for mixture nanoparticles reaches 473%, which is 9 times that of alumina nanoparticles and 12-47 times the graphene enhancement. The reason for this is because the deposition of alumina nanoparticles on the surface of the reduced graphene oxide greatly enhances the capillary force of the porous deposition surface. [PERSON] [111] and others studied the boiling heat transfer performance of water-based Al\({}_{2}\)O\({}_{3}\), GNs, and GONs nanofluids on the surface of the heating wire at a volume concentration of 0.001%. The results show that the CHF of Al\({}_{2}\)O\({}_{3}\), GNs, and GONs nanofluids increased by 152%, 84%, and 179%, respectively, compared to deionized water. The authors point out that the CHF enhancement cannot be explained simply by surface wettability and capillary action of nanoparticle deposits.