Phase Change Material Particles and Their Application in Heat Transfer Fluids - Low-cost Nanomaterials: Toward Greener and More Efficient Energy Applications - page 471

Fig. 18 Correlation function
of the scattered light for the
12 vol% water in FC-72
nanoemulsion fluids.
Measurements taken by a
Photocor-Complex DLS
instrument [ 15 ]

0.4

Water-in-FC72
T=25 o C

0.3

0.2

0.1

0

10 -7 10 -6 10 -5 0.0001 0.001 0.01

Delay Time (s)

Fig. 19 Relative thermal
conductivity of FC-72
nanoemulsion fluids versus
water volume concentration.
The effective thermal
conductivity estimated from
the effective medium theory
for spherical particles is
shown for comparison [ 15 ]

Weight Fraction (%)

0 1 2 3 4 5 6 7 8

100

Experiment
Effective Medium Theory

80

Water-in-FC72

60

40

G=65 MW/m 2 K

20

15 M W/m 2 K

0

0 5 10 15

Volume Fraction (%)

When the water nanodroplets do not undergo solid-liquid phase change, the
specific heat of the water in FC-72 nanoemulsion fluids follows the simple mixture
rule:

C nanoemulsion ¼ 1 ffi U ð Þ c oil þ UC water ð 10 Þ

where U represents the concentration of the ''water'' phase. The specific heat of
the pure FC-72 and water in FC-72 nanoemulsion fluids are measured using a
Differential Scanning Calorimetry (DSC). The specific heat of FC-72 and water-in-
FC-72 nanoemulsion fluids is measured using a TA-CC100 DSC. The measured
and calculated heat capacities of the water in FC-72 nanoemulsion fluids are