308
B. Naik et al.
The Drew and Passman [13] relation is used for calculating the viscosity of
nanofluid.
μ n f = μ f (1 + 2.5φ)
(9)
By using Choi relation [14], the density of nanofluid is calculated.
ρ n f = (1 − φ)ρ f + φρ s
(10)
Xuan and Roetzel co-relation [15, 16] is used for the calculation of the heat
capacity.
C p
n f
=
(1 − φ)(ρC p ) f + φ(ρC p ) s
ρ n f
(11)
Maxwell-Garnett’s approximation equation for thermal conductivity [7]
k stationary
k f
=
k s + 2k f − 2φ
k f − k s
k s + 2k f + φ
k f − k s
(12)
The ANSYS FLUENT 17.1 was utilized in the current investigation. The program
utilizes a method dependent on the control volume hypothesis to change over
exemplary singular stage conservation conditions to mathematical conditions. The
SIMPLE semi-certain strategy for pressure connected conditions was utilized to
combine the weight and speed. The conditions were characterized at the inlet
boundary as mass flow inlet and pressure outlet for outlet boundary. The magnitude
of inlet velocity was specifically determined and velocity direction was considered as
normal to the boundary. The velocity values and the temperature values are indicated.
3 Results and Discussion
The geometry of the domains and meshing was done by ANSYS 17.1. The cut cell
method was used for meshing. The geometrical config of double pipe for CFD simulation is shown in Fig. 1a. The model was meshed by 80,340 unstructured quadrilateral
cells. The flow rates applied for the hot fluid (nanofluid) are 100, 150, 200, 250, and
300(l/h) and the cold fluid was kept constant at 90(l/h). The temperatures distributed
in the double pipe are ranged from 296 to 323 K which indicates the temperature
contour of the nanofluid is shown in Fig. 1b.
Figure 2a–c illustrates the effects of Al 2 O, SiO 2 , Fe 3 O 4 nanofluid on the heat
transfer rate Q(W ) versus flow rate (l/h) are seen. The 5% of Al 2 O 3 nanofluid is 19%
higher than that of 2% Al 2 O 3 . The 5% of SiO 2 (nanofluid) is 12% is higher than that
of 2% SiO 2 (nanofluid). The 5% of Fe 3 O 4 (nanofluid) is 3.27% is higher than that
of 2% Fe 3 O 4 (nanofluid).
B. Naik et al.
The Drew and Passman [13] relation is used for calculating the viscosity of
nanofluid.
μ n f = μ f (1 + 2.5φ)
(9)
By using Choi relation [14], the density of nanofluid is calculated.
ρ n f = (1 − φ)ρ f + φρ s
(10)
Xuan and Roetzel co-relation [15, 16] is used for the calculation of the heat
capacity.
C p
n f
=
(1 − φ)(ρC p ) f + φ(ρC p ) s
ρ n f
(11)
Maxwell-Garnett’s approximation equation for thermal conductivity [7]
k stationary
k f
=
k s + 2k f − 2φ
k f − k s
k s + 2k f + φ
k f − k s
(12)
The ANSYS FLUENT 17.1 was utilized in the current investigation. The program
utilizes a method dependent on the control volume hypothesis to change over
exemplary singular stage conservation conditions to mathematical conditions. The
SIMPLE semi-certain strategy for pressure connected conditions was utilized to
combine the weight and speed. The conditions were characterized at the inlet
boundary as mass flow inlet and pressure outlet for outlet boundary. The magnitude
of inlet velocity was specifically determined and velocity direction was considered as
normal to the boundary. The velocity values and the temperature values are indicated.
3 Results and Discussion
The geometry of the domains and meshing was done by ANSYS 17.1. The cut cell
method was used for meshing. The geometrical config of double pipe for CFD simulation is shown in Fig. 1a. The model was meshed by 80,340 unstructured quadrilateral
cells. The flow rates applied for the hot fluid (nanofluid) are 100, 150, 200, 250, and
300(l/h) and the cold fluid was kept constant at 90(l/h). The temperatures distributed
in the double pipe are ranged from 296 to 323 K which indicates the temperature
contour of the nanofluid is shown in Fig. 1b.
Figure 2a–c illustrates the effects of Al 2 O, SiO 2 , Fe 3 O 4 nanofluid on the heat
transfer rate Q(W ) versus flow rate (l/h) are seen. The 5% of Al 2 O 3 nanofluid is 19%
higher than that of 2% Al 2 O 3 . The 5% of SiO 2 (nanofluid) is 12% is higher than that
of 2% SiO 2 (nanofluid). The 5% of Fe 3 O 4 (nanofluid) is 3.27% is higher than that
of 2% Fe 3 O 4 (nanofluid).