Figure 4

SHCs of molten salt, nanofluids with alumina NPs, bulk alumina, solid salt, and solid salt doped with alumina NPs. (a) molten-salt (solid and dash lines, measured using Q20 of TA and 7020 of EXSTAR, respectively) and nanofluids having 13-nm alumina NPs at 0.9 (red solid square), 2.7 (red solid circle), and 4.6 vol.% (red solid triangle), respectively, and nanofluids having 90-nm alumina NPs at 0.9 (blue open square), 2.7 (blue open circle), and 4.6 vol.% (blue open triangle), respectively; (b) 13-nm alumina NP (red solid square), 90-nm alumina NP (blue open square), and bulk alumina (dark solid circle) [16]; and (c) solid salt (dark dash line) and solid salt doped with 13-nm alumina NPs at 0.9 (red solid square), 2.7 (red solid circle), and 4.6 vol.% (red solid triangle), respectively, and 90-nm alumina NPs at 0.9 (blue open square), 2.7 (blue open circle), and 4.6 vol.% (blue open triangle), respectively.