Figure captions:

Fig.S1 S1a: nanofluid image for Fe3O4 in PEG at x1=0.3995×10-2. S1b: nanofluid image for Fe3O4 nanoparticles coated with oleic acid - PEG with PEG: oleic acid ratio of 1:1at different volume fractions of Fe3O4.

Fig. S2S2a: Shear stress versus shear rate for PEG-oleic acid solution with PEG mole fraction of 0.44446. S2b: Shear viscosity versus shear rate for PEG-oleic acid solution with PEG mole fraction of 0.44446.

Fig. S3 S3a: Shear stress versus shear rate for nanofluid of Fe3O4 nanoparticles coated with oleic acid dispersed in PEG (PEG: oleic acid ratio of 1:1) at φ1=0.301%, different magnetic field and T=298.15 K. S3b: Shear viscosity versus shear rate for nanofluid of Fe3O4 nanoparticles coated with oleic acid dispersed in PEG (PEG: oleic acid ratio of 1:1) at φ1=0.301%, different magnetic field and T=298.15 K.

Fig. S4 S4a: Shear stress versus shear rate for nanofluid of Fe3O4 nanoparticles coated with oleic acid dispersed in PEG (PEG: oleic acid ratio of 1:1) at φ1=1.502%, different magnetic field and T=298.15 K. S4b: Shear viscosity versus shear rate for nanofluid of Fe3O4 nanoparticles coated with oleic acid dispersed in PEG (PEG: oleic acid ratio of 1:1) at φ1=1.502%, different magnetic field and T=298.15 K.

Fig. S5 S5a: Shear stress versus shear rate for nanofluid of Fe3O4 nanoparticles coated with oleic acid dispersed in PEG (PEG: oleic acid ratio of 1:1) at φ1=4.440%, different magnetic field and T=298.15 K. S5b: Shear viscosity versus shear rate for nanofluid of Fe3O4 nanoparticles coated with oleic acid dispersed in PEG (PEG: oleic acid ratio of 1:1) at φ1=4.440%, different magnetic field and T=298.15 K.

Fig. S6 S6a: Shear stress versus shear rate for nanofluid of Fe3O4 nanoparticles coated with oleic acid dispersed in PEG (PEG: oleic acid ratio of 1:1) at φ1=6.483%, different magnetic field and T=310.15 K. S6b: Shear viscosity versus shear rate for nanofluid of Fe3O4 nanoparticles coated with oleic acid dispersed in PEG (PEG: oleic acid ratio of 1:1) at φ1=6.483%, different magnetic field and T=310.15 K.

Fig. S7 S7a: Shear stress versus shear rate for nanofluid of Fe3O4 nanoparticles coated with oleic acid dispersed in PEG (PEG: oleic acid ratio of 1:1) at φ1=6.483%, different magnetic field and T=323.15 K. S7b: Shear viscosity versus shear rate for nanofluid of Fe3O4 nanoparticles coated with oleic acid dispersed in PEG (PEG: oleic acid ratio of 1:1) at φ1=6.483%, different magnetic field and T=323.15 K.

Fig. S8Experimental and calculated isentropic compressibility, κs, plotted against mole fraction of Fe3O4 nanoparticle, x1, or PEG, x2, for nanofluids of Fe3O4 – PEG and Fe3O4 coated with oleic acid– PEG (PEG: oleic acid ratio of 1:1) and PEG-oleic acid solution at different temperatures.

S1a

S1b

Fig. S1

S2a

S2b

Fig. S2

S3a

S3b

Fig. S3

S4a

S4b

Fig. S4

S5a

S5b

Fig. S5

S6a

S6b

Fig. S6

S7a

S7b

Fig. S7

Fig. S8

Eyring-NRTL-Carreau-Yasuda model used in this work is as follow

(S1a)

, . (S1b)

In above relations V1and V2 are the molar volume of Fe3O4nanoparticles and PEG, respectively; η1and η2 are the viscosity of Fe3O4nanoparticles and PEG, respectively; is high shear rate viscosity,φI is the volume fraction of component I, equal to in which xI is the mole fraction of component I. T is temperature and R is the universal constant of gases. a12, b12, a21, b21, a, n and λ are empirical parameters of Eyring-NRTL-Carreau-Yasuda model. Subscripts 1 and 2 stand for Fe3O4nanoparticles and PEG molecules, respectively. α is the non randomness factor which was set to 0.2 in this work. Viscosity of Fe3O4nanoparticles is treated as an adjustable parameter and set to 1000 for obtaining good result.

Eyring-mNRF-Carreau-Yasuda model is as following equation

(S2a)

,(S2b)

, ,(S2c)

where approximates the ratio of the molar volume of the PEG and Fe3O4nanoparticles; and ; ,, , a, n and λ are the parameters of Eyring-mNRF-Carreau-Yasuda model. Z is the nonrandom factor which was set to 8 in this work.

The Krieger-Dougherty-Carreau-Yasuda model is as follow

(S3)

where is the maximum particle volume fraction and is the intrinsic viscosity. These quantities along with a, n and λ were set as empirical parameters in this work.

Table S1

Parameters of Eyring-NRTL-Carreau-Yasuda, Eyring-mNRF-Carreau-Yasuda and Krieger-Dougherty-Carreau-Yasuda models along with absolute average relative deviation, AARD,a and standard deviation, σ, b obtained from fitting the viscosity values of Fe3O4-PEG nanofluids

Eyring-NRTL-Carreau-Yasuda model
a12 / b12 / a21 / b21 / λ / a / n / 100.AARD
(σ (Pa.s))
0.06305 / 0.3766 / 0.06305 / 0.6404 / 0.5569 / 0.1193 / -0.7828 / 9.32
(0.012)
Eyring-mNRF-Carreau-Yasuda model
/ / / / λ / a / n / 100.AARD
(σ (Pa.s))
26.54 / 0.2555 / 6.284 / 0.3691 / 1.505 / 0.1467 / -0.964 / 9.64
(0.013)
Krieger-Dougherty- Carreau-Yasuda model
/ / λ / a / n / 100.AARD
(σ (Pa.s))
0.03733 / 1.945 / 880.8 / -0.808 / 8229 / 3.89
(0.009)

a in which N is the total number of data points and Y is the number of parameters. b.

1