Heat pipe with fins thermal analysis

Heat Pipe with Fins Thermal Analysis
Daniel Leon
Department of Mechanical Engineering and Materials Science
Swanson School of Engineering, University of Pittsburgh
DBL10@pitt.edu
(724) 914-1574
Content:
A. Memo & Supporting Document
 Introduction, problem statement, and supporting analysis to be used in conjunction with simulation guidelines
B. Simulation Guidelines
 Step-by-step conditional modeling and simulation of given problem
C. Resource 1 - Example Problem (Motorcycle Engline Cylinder)
 Verification for analysis of heat pipe (from textbook)
D. Resource 2 – Glycol and Convective Heat Transfer Study
 Used to determine fluid properties in convection
E. Resource 3 – Stainless Steel Grade AISI 321
 Used to determine thermal conductivity

MEMO TO: Dr. David Schmidt, PhD
FROM: Daniel Leon
DATE: December 11, 2018
SUBJECT: Senior Design Project Simulation Component Substitute for Engineering Simulation in
Design Certificate Achievement
The following document serves as the introduction, problem statement, and supporting analysis for the
MEMS 1121 original simulation problem submitted. This document should be used complimentarily with
the PowerPoint guidelines of simulation. As emphasized in lecture, the simulation strategy is ineffective
unless the fundamental theory behind the problem (mechanics, thermodynamics, vibrations, etc.) is
understood. The submission of this document, as well as the simulation guidelines and pertinent CAD
files, will act as a substitute for the Engineering Simulation in Design Certificate requirement listed below…
This problem uses a finned-tube heat exchanger as an example of improved heat transfer through the use
of extended surfaces. Total heat transfer rate is compared on a pipe with and without equally spaced
annular fins. The hand calculation of these answers is compared with simulation results using “Heat Pipe
with Fins.igs” and ANSYS Steady-State Thermal Analysis. Problem construction and verification was
derived from Example 3.10 in Fundamentals of Heat and Mass Transfer, 7th
Edition (Bergman, et. Al).
The results from hand calculations show a theoretical total heat transfer value of 16.81 kW for the heat
pipe with annular fins and 15.28 kW without annular fins. When simulated in ANSYS Steady-State
Thermal, total heat transfer values were found to be 18.93 kW (with fins, 12% error from theoretical) and
15.28 kW (without fins, 0% error from theoretical). Mesh sizing is a possible source of error resulting in
variance found in the simulated vs. theoretical answers and should be explored further.

Introduction
A heat exchanger is a device that allows heat from a fluid (a liquid or a gas) to pass to a second
fluid (another liquid or gas) without the two fluids having to mix together or come into direct
contact. The essential principle of a heat exchanger is that it transfers the heat without
transferring the fluid that carries the heat. They are widely used in space heating, refrigeration,
air conditioning, power stations, chemical plants, petrochemical plants, petroleum refineries,
natural-gas processing, and sewage treatment.
Finned tube heat exchangers have tubes with extended outer surface area (“fins”) to enhance
the heat transfer rate by increasing the effective heat transfer surface area between the tubes
and surrounding fluid. The fluid surrounding the finned tubes may be process fluid or air.

Problem Statement
The heat pipe of a finned-tube heat exchanger is constructed of AISI 321 annealed, stainless steel
(DN 80 mm STD). Consider a length of 0.6m, which under normal operating conditions the outer
surface of the pipe is at a temperature of 87°C. The pipe is exposed to liquid glycol at 30°C and a
convective heat transfer coefficient of 1600 W/(m^2*°C). Annular fins are integrally cast with
the pipe to increase heat transfer to the surroundings. Consider ten such fins, which are of
thickness 10mm, length 20mm, and equally spaced. What is the increase in heat transfer due to
the fins?
Assumptions
1. Steady-state conditions.
2. One-dimensional radial conduction in fins.
3. Constant properties.
4. Negligible radiation exchange with surroundings.
5. Uniform convection coefficient over outer surface (with or without fins).

Thermal Analysis
MEMS 1121: Term 1, Week X
Heat Pipe with Fins

Define a Steady-State Thermal Analysis Template

Verify unit assignment – Metric (kg, m, s, °C, A, N, V)

Add “Steel Stainless” (Thermal Materials) to Engineering Data

Define Thermal Conductivity – 16.1 W/(m*°C)

Define a Body Sizing Control – 5mm

Define Material Properties– Steel Stainless

Define Prescribed Surface Temp – 87°C

Define Convection – 30 °C, 1600 W/(m^2*°C)

Create Solution – Reaction Probe (Surface Integral of Heat Transfer)
Heat transfer rate
with fins

Regenerate Solution – Reaction Probe
Heat transfer rate
without fins

may adversely influence overall thermal performance. An effective circuit resistance may
again be obtained, where, with the contact resistance,
(3.109)
It is readily shown that the corresponding overall surface efficiency is
(3.110a)
where
(3.110b)
In manufacturing, care must be taken to render Rt,c Ӷ Rt,f.
EXAMPLE 3.10
The engine cylinder of a motorcycle is constructed of 2024-T6 aluminum alloy and is of
height H ϭ 0.15 m and outside diameter D ϭ 50 mm. Under typical operating conditions
the outer surface of the cylinder is at a temperature of 500 K and is exposed to ambient air
at 300 K, with a convection coefficient of 50 W/m2
⅐K. Annular fins are integrally cast with
the cylinder to increase heat transfer to the surroundings. Consider five such fins, which are
of thickness t ϭ 6 mm, length L ϭ 20 mm, and equally spaced. What is the increase in heat
transfer due to use of the fins?
SOLUTION
Known: Operating conditions of a finned motorcycle cylinder.
Find: Increase in heat transfer associated with using fins.
Schematic:
Assumptions:
1. Steady-state conditions.
2. One-dimensional radial conduction in fins.
3. Constant properties.
H = 0.15 m
S
t = 6 mm
Tb = 500 K
T∞ = 300 K
h = 50 W/m2•K
Air
Engine cylinder
cross section
(2024 T6 Al alloy)
r1 = 25 mm
L = 20 mm
r2 = 45 mm
C1 ϭ 1 ϩ ␩fhAf (RЉt,c/Ac,b)
ho(c) ϭ 1 Ϫ
NAf
At
΂1Ϫ
hf
C1
΃
Rt,o(c) ϭ
␪b
qt
ϭ 1
ho(c)hAt
172 Chapter 3 ᭿ One-Dimensional, Steady-State Conduction
CH003.qxd 2/24/11 12:26 PM Page 172
www.FluidMechanics.ir

4. Negligible radiation exchange with surroundings.
5. Uniform convection coefficient over outer surface (with or without fins).
Properties: Table A.1, 2024-T6 aluminum (T ϭ 400 K): k ϭ 186 W/m ⅐K.
Analysis: With the fins in place, the heat transfer rate is given by Equation 3.106
where Af ϭ 2␲(r2
2c Ϫ r2
1) ϭ 2␲[(0.048 m)2
Ϫ (0.025 m)2
] ϭ 0.0105 m2
and, from Equa-
tion 3.104, At ϭ NAƒ ϩ 2␲r1(H Ϫ Nt) ϭ 0.0527 m2
ϩ 2␲(0.025 m) [0.15 m Ϫ 0.03 m] ϭ
0.0716 m2
. With r2c/r1 ϭ 1.92, Lc ϭ 0.023 m, Ap ϭ 1.380 ϫ 10Ϫ4
m2
, we obtain
. Hence, from Figure 3.20, the fin efficiency is ␩ƒ Ϸ 0.95.
With the fins, the total heat transfer rate is then
Without the fins, the convection heat transfer rate would be
Hence
᭠
Comments:
1. Although the fins significantly increase heat transfer from the cylinder, considerable
improvement could still be obtained by increasing the number of fins. We assess this
possibility by computing qt as a function of N, first by fixing the fin thickness at
t ϭ 6 mm and increasing the number of fins by reducing the spacing between fins. Pre-
scribing a fin clearance of 2 mm at each end of the array and a minimum fin gap of
4 mm, the maximum allowable number of fins is N ϭ H/S ϭ 0.15 m/(0.004 ϩ 0.006)
m ϭ 15. The parametric calculations yield the following variation of qt with N:
The number of fins could also be increased by reducing the fin thickness. If the fin gap
is fixed at (S Ϫ t) ϭ 4 mm and manufacturing constraints dictate a minimum allowable
fin thickness of 2 mm, up to N ϭ 25 fins may be accommodated. In this case the para-
metric calculations yield
qt(W)
1600
155 11
Number of fins, N
1400
1200
1000
800
600
t = 6 mm
7 9 13
⌬q ϭ qt Ϫ qwo ϭ 454 W
qwo ϭ h(2␲r1H)␪b ϭ 50 W/m2
⅐ K(2␲ ϫ 0.025 m ϫ 0.15 m)200 K ϭ 236 W
qt ϭ 50 W/m2
⅐ K ϫ 0.0716 m2
΄1 Ϫ 0.0527 m2
0.0716 m2
(0.05)΅200 K ϭ 690 W
L3/2
c (h/kAp)1/2
ϭ 0.15
qt ϭ hAt ΄1 Ϫ
NAf
At
(1 Ϫ ␩f)΅␪b
3.6 ᭿ Heat Transfer from Extended Surfaces 173
CH003.qxd 2/24/11 12:26 PM Page 173

The foregoing calculations are based on the assumption that h is not affected by a
reduction in the fin gap. The assumption is reasonable as long as there is no interaction
between boundary layers that develop on the opposing surfaces of adjoining fins. Note
that, since NAf ӷ 2␲r1(H – Nt) for the prescribed conditions, qt increases nearly lin-
early with increasing N.
2. The Models/Extended Surfaces option in the Advanced section of IHT provides ready-
to-solve models for straight, pin, and circular fins, as well as for fin arrays. The models
include the efficiency relations of Figures 3.19 and 3.20 and Table 3.5.
EXAMPLE 3.11
In Example 1.5, we saw that to generate an electrical power of P ϭ 9 W, the temperature of
the PEM fuel cell had to be maintained at Tc Ϸ 56.4ЊC, which required removal of 11.25 W
from the fuel cell and a cooling air velocity of V ϭ 9.4 m/s for Tȍ ϭ 25ЊC. To provide
these convective conditions, the fuel cell is centered in a 50 mm ϫ 26 mm rectangular duct,
with 10-mm gaps between the exterior of the 50 mm ϫ 50 mm ϫ 6 mm fuel cell and the
top and bottom of the well-insulated duct wall. A small fan, powered by the fuel cell, is
used to circulate the cooling air. Inspection of a particular fan vendor’s data sheets suggests
that the ratio of the fan power consumption to the fan’s volumetric flow rate is
for the range
H H
W
Wc
tc
Lc
Fuel cell
Duct
Without
finned
heat sink
W
Wc
tb
Lf
tf
a
Lc
Duct
With
finned
heat sink
Air Air
T∞, f
Fuel cell
•
᭙T∞, f
•
᭙
10Ϫ4
Յ᭙˙
f Յ10Ϫ2
m3
/s.Pf /᭙˙f ϭ C ϭ 1000 W/(m3
/s)
qt(W)
3000
255 15
Number of fins, N
2500
2000
1500
1000
500
(S – t) = 4 mm
10 20
174 Chapter 3 ᭿ One-Dimensional, Steady-State Conduction
CH003.qxd 2/24/11 12:26 PM Page 174

237
Int. J. Nanosci. Nanotechnol., Vol. 10, No. 4, Dec. 2014, pp. 237-244
Investigation of Heat Transfer Coefficient of Ethylene
Glycol/ Graphenenanofluid in Turbulent Flow Regime
A. Ghozatloo1,2
, M. Shariaty-Niasar2
and A.M. Rashidi1
1. Faculty member of Research Institute of Petroleum Industry (RIPI), West blvd. Azadi Sport Complex,
Tehran, I.R.Iran
2. Transport phenomena and Nanotechnology Laboratory, Department of Chemical Engineering, College of
Eng., University of Tehran, Tehran, I.R.Iran
(*) Corresponding author: ghozatlooa@ripi.ir
(Received: 04Feb. 2014 and Accepted: 26 Oct. 2014)
Abstract:
In the present work, graphene was synthesized by chemical vapor deposition (CVD) method. The structure of
graphene was then confirmed by X-Ray diffraction (XRD) and scanning electron microscope (TEM) images.
After that, mixed acid method (H2SO4/HNO3) was used to make the structure of synthesized
graphenehydrophilic. In this method, carboxylate and hydroxide groups were linked to the edges of
graphenenano sheets. The hydrophilic graphene was added to ethylene glycol (EG) with the concentrations
of 0.100, 0.125, and 0.150 wt%, and the mixtures were sonicated at 60°C for 3hours to prepare the ethylene
glycol/ graphenenano fluid. The thermal conductivity of samples was measured by KD2, while
thermophysical properties of were estimated by valid theoretical equations. Then heat transfer coefficient of
the samples was measured by using a straight pipe under constant heat flux and a turbulent flow regime.
According to the obtained results, thermal conductivity and heat transfer coefficient increased by 21.2% and
42.4%, respectively, only by the addition of 0.15wt % of graphene in to ethylene glycol. Also thermal
conductivity and heat transfer coefficient were improved by increasing the temperature and concentration of
graphene.
Keywords: Graphene, nanofluid, Ethylene glycol, Thermal conductivity, Heat transfer coefficient, Turbulent
flow.
1. INTRODUCTION
Nanofluids (NFs) are stable suspensions, which are
made by uniform dispersion of nanoparticles (NPs)
in fluids [1]. The thermal conductivity of NFs is
significantly higher than conventional fluids due to
the stability, particle size, and higher conductivity
[2]. Therefore, application of NFs in heat
exchangers is so suitable [3]. In chemical
processes, one of the most important devices
related to energy and heat transfer is heat
exchanger. The poor heat transfer properties of
employed fluids (such as water, mineral oil, and
ethylene glycol (EG)) are obstacles for using
different types of heat exchangers. Efforts have
been done to enhance heat transfer, reduce the heat
transfer time, minimize size of heat exchangers,
finally increase energy and fuel efficiencies. EG
has been used widely as the cooling fluid and anti-
freezing agent in heat exchangers and thus
improving its thermal properties that are of a great
importance [4]. Since nano particles (metallic,
nonmetallic, and carbon structures) have thermal
conductivity higher than that of fluids, when they

238 Ghozatloo et al.
are dispersed in the fluids (NFs) result in higher
heat transfer characteristics and modify heat
transfer performance of fluids.
Graphene, a sheet with thickness of one
carbon atom, is made from carbon atoms in a
hexagonal lattice structure. The thermal
conductivity of graphene is about 5000 W/mK,
which is much higher than that of diamond (1800
W/mK) and carbon nanotubes (CNT) (3000
W/mK) [5]. All experimental results have
indicated the enhancement of thermal conductivity
by addition of NPs [6-14] also there are several
published studies on the forced convective heat
transfer coefficient of NFs, and most of them are
under the constant heat flux or constant
temperature boundary conditions at wall of tubes
and channels. The experimental results for forced
convection inside a channel show that convective
heat transfer coefficient of NFs is enhanced
compared to base fluid [15-21].The objective of
the present study is to investigate the heat transfer
characteristics (such as overall and convective heat
transfer coefficients, and Nusselt number)
graphene /EG NFs for turbulent flow in a
horizontal stainless steel shell and tube heat
exchanger.
2. EXPERIMENT
2.1. Synthesis and Characterization of
Graphene
In this research, graphene was grown over copper
foils by the CVD method. A mixture of methane
and hydrogen gas was used under atmospheric
pressure as the feed. First, copper foils were
inserted inside the reactor, and the reactor was
heated up to 1050°C by using hydrogen flow with
flowrate of 910 sccm. After 40 min, methane was
introduced to the system with flowrate of 335
sccm, and hydrogen flow was decreased to 665
sccm. The furnace, which applied to synthesize of
graphene,is represented in Figure 1.
As a result of methane decomposition,
hexagonal structures of graphene were grown over
copper foils. The reactor was cooled after 15 min
with temperature slop of 180°C/min [22]. After
cooling procedure, purification treatment was
performed. X-ray diffraction analysis of
synthesized graphene sheets has been represented
in Figure 2.
Figure 1. The furnace which applied to synthesize of
graphene
Figure 2. XRD of graphene synthesized by CVD method
According to this figure, there is a short and
wide peak at 26.5°, which is consistent with the
data in the literature [23]. It is known that copper
has a peak at 46° and rolling of carbon nanotubes
is attributed to 42° and 76.8° [24]. As it can be
seen from the figure, there is not any copper in the
system, and the graphene sheets have not been
rolled. Therefore, it can be concluded that the
obtained graphene is pure. By using Scherrer
equation [25], the crystalline size of graphene is
calculated as 2.1 nm, and when it is divided by the
distance of graphene layers (3.4 Å) [26], the
number of graphene sheets is calculated as 6.1
layers [23].

International Journal of Nanoscience and Nanotechnology 239
For studying the morphology of graphene,
TEM analysis was used (Figure 3). As indicated
from this figure, the synthesized graphene has a
disordered structure similar to a folded paper,
which is attributed to the nature of pure graphene
and its natural stability [27].
Figure 3. TEM image of graphene synthesized by CVD
method
2.2. Hydrophilic of graphene and nanofluid
preparation
Since the synthesized graphene is hydrophobic, it
precipitates rapidly in polar fluids. Thus for
increasing the stability, graphene is converted to
hydrophilic graphene oxide by using an acidic
method (a mixture of H2SO4 and HNO3 with the
ratio of 3–1 for 3 hours at 60 °C) [28]. For
checking the presence of carboxylic groups over
graphene after acidic oxidation, FTIR spectra of
GO sample was compared with that of graphene
sample.
Figure 4. FTIR spectra of a) Graphene b) Graphene
oxide
As shown in part b of Figure 4, peaks at 1218
cm-1
and 3410 cm-1
are attributed to C-O bond and
hydroxide group (OH), confirming the presence of
carboxylic group (-COOH) [29]. The existence of
peak at 1717 cm-1
indicates that during the
oxidation of graphene, some C=O group are
bonded to the edges of graphene sheets [30] and
the shift from 1735 to 1718 cm-1
reveals high
number of hydroxide groups which are bonded to
graphene [31]. Also the shift of 1574 cm-1
which is
attributed to C=O bond, to the right hand side of
1581 cm-1
indicates the presence of carboxylate
group over graphenestructure [32] and as a result it
can be concluded that a good oxidation has been
performed. After making graphene sheets,
hydrophilic nanofluid samples (GO/EG) were
prepared. Graphene powder was added with
volumetric percentages of 0.05, 0.075, and 9.1% to
EG as the base fluid and the mixture was sonicated
for 45 min at ambient temperature. Characteristics
of samples have been represented in Table 1.
Table 1. Profile samples Nano fluids graphene oxide /
ethylene glycol
Grapheneoxide (wt. %)SampleNo
0.100EG/ARG-11
0.125EG/ARG-22
0.150EG/ARG-33
2.3. Calibration of the system
The experimental set up includes test section,
pump and fluid cycling system, a shell and tube
heat exchanger, and a circulator. The test section
consists of a thin and smooth copper pipe with
length of 1 meter, and it is covered by electrical
element for providing constant heat flux. Thermal
insulator has been used over the element for
isolating the test section from the surrounding.
Five thermocouples were used with equal distances
along the copper pipe for measuring the wall
temperatures and two additional thermocouples
were used for measuring the fluid temperature in
inlet and outlet sections.
The working fluid is pumped into the system
and after heating inside the copper pipe, it flows
through the heat exchanger. The exchanger is
connected to the circulator, and thus, it makes the

temperature of the fluid to decrease. After that, the
fluid is collected in a reservoir for the removal of
its disturbance, and it is then pumped again into the
system, and the cycle is repeated. Figure 5
represents the schematics of the experimental
setup.
Figure 5. Experimental setup of shell & tube heat
exchanger
Calibration of the system was performed by
calculating one of base fluid properties (EG). The
aim of calibration of the system is to ensure the
correctness of the results, repeatability of the tests,
and error evaluation. Therefore, Nusselt (Nu)
number was measured and was compared with the
theoretical relations [27]. EG was flowed inside the
system by a flowrate of 0.23lit/min and Reynolds
(Re) number of 2840. The element created a heat
flux of 352.1W over the outlet surface of copper
pipe. After some time, the steady state was reached
and the inlet and outlet temperatures were
recorded. Thermophysical properties of EG was
calculated from standard tables at average
temperature ( ). The results are
represented in Table 2 [33].
The heat transferred from hot wall to the
fluid was calculated from
as 339.4W,
which is almost the same as the heat flux produced
by the element. The constant flux is calculated
from as 9368.7W/m2
. The average
temperatures of wall and fluids were calculated
from .
The calculated values for average wall and
fluid temperatures are as 35.7 and 32.2°C. The
average heat transfer coefficient is calculated from
as 2602.4W/m2
K and the Nu
number is obtained as 103.51. In turbulent flow
inside pipe, if 4.4*Re1/6
< L/D, then the flow is
fully developed [34], and the Nu number is
calculated from below equation [35] as
. By replacing the values
in this formula, the theoretical Nu number is
calculated as 115.35 which is just 10.2% different
from experimental value. This difference is
acceptable as a low error, and it confirms that the
system is calibrated in turbulent flow regime.
3. RESULTS AND DISCUSSION
3.1. Calculation of thermophysical
properties of EG/ graphenenanofluid
The thermophysical properties of nanofluids
including the density, viscosity, and heat capacity
are usually different from the base fluid, and they
have an important impact in heat transfer
coefficient. These properties are used in the
measurement of heat transfer coefficient and
therefore they are assessed before calculating the
heat transfer coefficient. For evaluation of
thermophysical properties of nanofluids usually
theoretical relations are used which are based on
the single phase fluid. This assumption is correct
by reducing the concentration of nanoparticles and
due to very low concentration of graphene in this
work, it can be used. The viscosity of suspension
with concentrations lower than 4% can be obtained
from Drew and Passma relationship:
[36]. The density of stable
nanofluid can be obtained by Pak & Cho
formula: [37]. Also the
average heat capacity of nanofluids can be
obtained from Xuan & Roetzel equation:
[38]. The
thermal conductivity of nanofluids were
measured by hot-wire method by using KD2
[39]. The thermophysical properties of
samples have been represented in Table 3.

Table 2. Thermo physical properties of EG- 32.2°C
Density (Kg/m3
)Viscosity (Kg/m.s)Specific Heat(J/Kg.K)Thermal conductivity(W/m.K)
1110.10.01522391.40.269
Table 3. Thermo physical properties of EG/G NFs- 32.2°C
samole Graphene (wt%)
Thermal
conductivity(W/m.K)
Density
(Kg/m3
)
Viscosity (cp)
Specific
Heat(J/Kg.K)
EG 0 0.253 1109.1 14.51 2427.7
Graphene 1 5000 2200 - 790.1
EG/ARG-1 0.1 0.312 1218.2 18.14 2131.9
EG/ARG-2 0.125 0.324 1250.3 19.24 2051.8
EG/ARG-3 0.15 0.338 1283.9 20.21 1969.5
According to this table, it can be concluded
that the presence of graphene in EG leads to an
increase in density, viscosity and thermal
conductivity, and a decrease in specific heat
capacity. Moreover, density and viscosity of
nanofluids are enhanced by increasing the graphene
concentration, while the heat capacity decreases. For
maximum concentration of graphene (0.15 wt%),
the density and viscosity of base fluid increased by
15.76% and 39.28%, respectively, and the heat
capacity decreased by 18.9%.
3.2. Measurement of local heat transfer
coefficient for EG/graphene nanofluid in
turbulent flow
Since the viscosity of graphene nanofluids is
higher than EG, for making a turbulent flow under
a constant Reynolds number, it is necessary to use
higher flowrates of nanofluid in comparison with
EG. For comparison, at first a constant Re number
was set for both of EG fluid and EG/
graphenenanofluid. This was reached by changing
the flowrate of fluid. By setting the flowrate of
samples, a constant Re number of 2840under
constant heat flux of 352.1 W was reached.
3.2.1. Measurement of average heat transfer
coefficient of EG/graphenenanofluid in
turbulent flow
Since it is common to use average heat transfer
coefficient for designing heat exchangers,
evaluation of this coefficient would be so useful.
The experimental values of average heat transfer
coefficient for EG/graphenenanofluid at different
temperatures are represented in Table 4.
According to Table 4, it can be seen that by
increasing the temperature and concentration, the
average heat transfer coefficient improves. For
instance at average temperature of 30°C, just by
adding 0.1 wt% of graphene, heat transfer
coefficient increases by 27.9% in turbulent flow.
One reason of such increase can be related to the
21.2% increase in thermal conductivity of
nanofluid. Furthermore, it can be observed that an
increase in temperature at higher concentrations of
graphene in EG, enhances the heat transfer rate,
because at graphene concentrations of three times
of initial concentration. As a result, the trend of
heat transfer coefficient enhancement in
EG/graphene nanofluid will be a function of
conditions, and it will increase by temperature
increase. The maximum heat transfer coefficient is
related to sample EG/ARG-3 with 2990.8W/m2
K
at 40°C.
Moreover as it can be seen from Figure 6,
although the trend of heat transfer coefficient
enhancement is similar to EG, but the enhancement
rate increases by graphene concentration. It should
be noted that the presence of graphene in EG has
more effect in enhancement of thermal
conductivity in comparison with heat transfer
coefficient, and this effect increases by increasing
graphene concentration. Also since the distance
between curves increases by temperature, thus
temperature has more significant effect in heat
transfer enhancement, which makes the application
of EG/graphenenanofluid more interesting for heat
exchangers for cooling fluids with higher
temperatures, manufactured nanoparticles,
automotive, electronic, micro scale fluidic,
biomedical and photo catalysts.

Table 4. Heat transfer coefficient of EG/graphenenanofluid-Re=2840
(°C)Tave
Average heat transfer coefficient
(W/m2
.K)
Improvement than EG(%)
EG EG/ARG-1 EG/ARG-2 EG/ARG-3 EG/ARG-1 EG/ARG-2 EG/ARG-3
30 1608.4 2058.8 2190.6 2290.4 28 36.2 42.4
35 1723.2 2321.2 2407.3 2503.8 34.7 39.7 45.3
40 2033.3 2631.1 2871.0 2991.0 29.4 41.2 47.1
Figure 6. Heat transfer coefficient of EG/graphenenanofluid in various temperature
4. CONCLUSION
In this research, heat exchange coefficient of
EG/graphenenanofluid was investigated in fully
developed region of turbulent flow. Some
thermophysical properties of EG/
graphenenanofluid as well as heat transfer
coefficient was measured at different
concentrations. Thermal conductivities of
graphenenanofluid were measured by KD2 at three
concentrations of graphene. Also it was observed
that at lower temperatures, the presence of
graphene has more effect in thermal conductivity
in comparison with heat transfer coefficient, while
by increasing temperature, increase in heat transfer
coefficient is higher than thermal conductivity
enhancement. For instance by adding 0.1wt %
graphene to EG at 30°C, thermal conductivity and
heat transfer coefficient improve by 21.2 and
42.4%, respectively. Also increasing graphene
concentration affects some thermophysical
properties of EG (enhancement of density,
viscosity, and reduction of heat capacity), but
generally it improves the thermal behavior of
nanofluids. Heat transfer coefficient of
graphenenanofluid in turbulent flow and under
constant heat flux is an ascendant function of
concentration and temperature.
REFERENCES
1. France, J. L. Routbort, and S. U. S. Choi, Review and
comparison of nanofluid thermal conductivity and
heat transfer enhancements, Heat Transfer
Engineering., Vol. 29, No. 5, (2008), pp.432–460.
2. S. ZeinaliHeris, S.Gh. Etemad , M. Nasr Esfahany,
Experimental investigation of oxide nanofluids
turbulent flow convective heat transfer, International
Communications in Heat and Mass Transfer., Vol. 33,
No. 4, (2006), pp.529-535.
3. D. Wen, Y. Ding, Experimental investigation into
convective heat transfer of nanofluids at the entrance
region under turbulent flow conditions, International

Journal of Heat and Mass Transfer., Vol. 47, No. 24,
(2004), pp.5181-5188.
4. TessyTheres Baby and S Ramaprabhu, Investigation
of thermal and electrical conductivity of grapheme
based nanofluids, applied physics., Vol. 108, No.
124308, (2010), pp.1-8.
5. Chen L. and Xie H, Silicon Oil based multi walled
carbon nano tubes nano fluid with optimized thermal
conductivity enhancement, Colloids and surface A:
Physiochemical and Engineering Aspects., No. 30402,
(2009), pp.633-636.
6. X. Wang, X. Xu, S.U.S. Choi, Thermal conductivity
of nanoparticle-fluid mixture, Thermophys Heat
Transfer., Vol. 13, (1999), pp. 474–480.
7. S. Lee, S.U.S. Choi, S. Li, J.A. Eastman, Measuring
thermal conductivity of fluids containing oxide
nanoparticles, transaction of ASME, Heat Transfer.,
Vol. 121, (1999), pp.280–289.
8. S.K. Das, N. Putra, P. Thiesen, W. Roetzel,
Temperature dependence of thermal conductivity
enhancement of nanofluids, J. Heat Transfer., Vol.
125 (2003) 567–574.
9. H. Xie, J. Wang, T. Xi, F. Ai, Thermal conductivity
enhancement of suspensions containing nanosized
alumina particles, Appl. phys., Vol. 91, (2002),
pp.4568–4572.
10. H. Xie, J. Wang, T. Xi, F. Ai, Dependence of
thermal conductivity of nanoparticle-fluid mixture on
the base fluid, Mater. Sci. Lett., Vol. 21, (2002),
pp.1469–1471.
11. C.H. Li, G.P. Peterson, Experimental investigation
of temperature and volume fraction variations on the
effective thermal conductivity of nanoparticle
suspensions (nanofluids), Appl. Phys., Vol. 99,
(2006), pp.1–8.
12. J.A. Eastman, S.U.S. Choi, S. Li, W. Yu, L.J.
Thompson, Anomalously increased effective thermal
conductivities of ethylene glycol-based nanofluids
containing copper Nanoparticles, Appl. Phys. Lett.,
Vol. 78, (2001), pp.718–720.
13. S. Das, N. Putra, Temperature Dependence of
Thermal Conductivity Enhancement for Nanofluids,
Heat Transfer., Vol. 125, (2003), pp.28-36.
14. Y. Xuan, and Q. Li, Heat transfer enhancement of
nanofluids, Applied Physics., Vol. 106, (2009), pp.59-
70.
15. B.C. Pak, Y.I. Cho, Hydrodynamic and heat transfer
study of dispersed fluids with submicron metallic
oxide particles, Exp. Heat Transfer., Vol. 11, (1998),
pp.151– 170.
16. Y. Xuan, Q. Li, Investigation on convective heat
transfer and flow features of nanofluids, Heat
Transfer., Vol. 125, (2003), pp.151–155.
17. D. Wen, Y. Ding, Experimental investigation into
convective heat transfer of nanofluids at entrance
region under laminar flow conditions, Heat and Mass
Transfer., Vol. 47, (2004), pp.5181–5188.
18. Y. Yang, Z.G. Zhang, E.A. Grulke, W.B. Anderson,
G. Wu, Heat transfer properties of nanoparticle-in-
fluid dispersions (nanofluids) in laminar flow, Heat
Mass Transfer., Vol. 48, (2005), pp.1107–1116.
19. S. ZeinaliHeris, S.Gh. Etemad, M. Nasr Esfahani,
Experimental investigation of oxide nanofluids
laminar flow convective heat transfer, International
Communications Heat and Mass Transfer., Vol. 33,
(2006), pp.529–535.
20. Y. He, Y. Jin, H. Chen, Y. Ding, D. Cang, H. Lu,
Heat transfer and flow behavior of aqueous
suspensions of TiO2 nanoparticles (nanofluids)
flowing upward through a vertical pipe, Heat and
Mass Transfer., Vol. 50, (2007), pp.2272–2281.
21. H. Chen, W. Yang, Y. He, Y. Ding, L. Zhang, C.
Tan, A.A. Lapkin, D.V. Bavykin,Heat transfer and
flow behaviour of aqueous suspensions of TiO2
nanotubes (nanofluids), Powder Technol., Vol. 183,
(2008), pp.63–72.
22. Ahmad Ghozatloo, MojtabaShariaty-Niasar and Ali
MoradRashidi, Preparation of nanofluids from
functionalized Graphene by new alkaline method and
study on the thermal conductivity and stability,
International Communications in Heat and Mass
Transfer., Vol. 42, (2013), pp.89–94.
23. Hae-MiJu, Sung-Ho Choi and Seung Hun Huh, X-
ray Diffraction Patterns of Thermally-reduced
Graphenes, the Korean Physical Society., Vol. 57,
(2010), pp.1649-1652.
24. Pitamber Mahanandia, Jörg J. Schneider, Martin
Engel, Bernd Stühn, Somanahalli V. Subramanyam
and Karuna Kar Nanda, Studies towards synthesis,
evolution and alignment characteristics of dense,
millimeter long multiwalled carbon nanotube arrays,
Nanotechnol., Vol. 2, (2011), pp.293–301.
25. Hae-MiJu, Sung-Ho Choi and Seung Hun Huh, X-
ray Diffraction Patterns of Thermally-reduced
Graphenes, the Korean Physical Society., Vol. 57,
(2010), pp.1649-1652.
26.Guoxiu W., Juan Y., Park J., Xinglong G., Wang B.,
Liu H., and Yao J., Facile Synthesis and
Characterization of Graphene Nano sheets, Phys.
Chem. C., Vol. 112, (2008), pp.8192–8195.
27. Ahmad Ghozatloo, AlimoradRashidi,
MojtabaShariaty-Niassar, Convective heat transfer
enhancement of graphenenanofluids in shell and tube
heat exchanger, Experimental Thermal and Fluid
Science., Vol. 53, (2014), pp.136–141.

28. Hye Jin Yoo, KyoungHou Kim, Santosh Kumar
Yadav, Jae Whan Cho, Effects of carbon nanotube
functionalization and annealing on crystallization and
mechanical properties of melt-spun carbon
nanotubes/poly(ethylene terephthalate) fibers,
Composites Science and Technology., Vol. 72, (2012),
pp.1834–1840.
29. Hontoria-Lucas, C., López-Peinado, A. J., López-
González, J. de D., Rojas-Cervantes, M. L., Martín-
Aranda, R. M., Study of oxygen-containing groups in
a series of graphite oxides, Physical and chemical
characterization, Carbon., Vol. 33, (1995), pp.1585-
1592.
30. C. A. Dyke and J. M. Tour, Covalent
Functionalization of Single-Walled Carbon Nanotubes
for Materials Appli-cations, Physical Chemistry., Vol.
108, No. 51, (2004), pp.11151-11159.
31. Kuznetsova, A.; Mawhinney, D. B.; Naumenko, V.;
Yates Jr, J. T.; Liu, Smalley, R.E., Chem Phys Lett.,
Vol. 12, (2000), pp.292-321.
32. Jin Zhang, Hongling Zou, Quan Qing, Yanlian
Yang, Qingwen Li, Zhongfan Liu, Xinyong Guo, and
Zuliang Du, Effect of Chemical Oxidation on the
Structure of Single-Walled Carbon Nanotubes, Phys.
Chem. B., Vol. 107, (2003), pp.3712-3718.
33. Thermophysical Properties of Matter, Appendix A,
A.6, (2004), pp.1003-1016
34. J.H. Lienhard IV, J.H. Lienhard V, A Heat Transfer
Textbook, second ed., Phlogiston Press, (2002).
35. V. Gnielinski, New equations for heat and mass
transfer in turbulent pipe and channel flow, Chem.
Eng., Vol. 16, (1976), pp.359-372.
36. Drew D.A and Passman S.L, Theory of
Multicomponent Fluids, App. Math Sci., Springer-
Verlag., Vol. 135, (1999), pp.32-45.
37. Pak, B. C., and Cho, Y. I., Hydrodynamic and heat
transfer study of dispersed fluids with submicron
metallic oxide particles, Exper Heat Trans., Vol. 11,
No. 2, (1998), pp.151-170.
38. Y. Xuan, W. Roetzel, Conceptions for heat transfer
correlation of nanofluids, Heat Mass Transfer., Vol.
43, (2000), pp.3701–3707.
39. Jyothirmayee Aravind S.S. and Ramaprabhu S.,
Graphene wrapped multiwalled carbon nanotubes
dispersed nanofluids for heat transfer applications,
Applied Physics., Vol. 112, (2012), pp.124304-1-9.

www.steeleaglemalta.com info@steeleaglemalta.com +356.21.333.190
Stainless Steel grade AISI 321
Grade 321 is a stabilized austenitic stainless steel similar to Type
304 but with a titanium addition of at least five times the carbon
content. This titanium addition reduces or prevents carbide
precipitation during welding and in 800 – 1500 °F (427 – 816 °C)
service. It also improves the elevated temperature properties of the
alloy.
Grade 321H is a modification of 321 with a higher carbon
content, to provide improved high temperature strength.
Grade 304L is more readily available in most product forms, and
so is generally used in preference to 321 if the requirement is simply
for resistance to intergranular corrosion after welding. However 304L
has lower hot strength than 321 and so is not the best choice if the
requirement is resistance to an operating environment over about
500°C.
Grade 321 provides excellent resistance to oxidation and
corrosion and possesses good creep strength. It is used primarily in
applications involving continuous and intermittent service
temperatures within the carbide precipitation range of 800 – 1500 °F
(427 – 816 °C).

www.steeleaglemalta.com info@steeleaglemalta.com +356.21.333.190
Chemical Properties
Composition
321 321H 347
(%) (%) (%)
Carbon 0.08 max. 0.04-0.10 0.08 max.
Manganese 2.00 max. 2.00 max. 2.00 max.
Phosphorus 0.045 max. 0.045 max. 0.045 max.
Sulfur 0.030 max. 0.030 max. 0.030 max.
Silicon 0.75 max. 0.75 max. 0.75 max.
Chromium 17.00 – 19.00 17.00 – 19.00 17.00 – 19.00
Nickel 9.00 – 12.00 9.00 – 12.00 9.00 – 13.00
Nitrogen 0.10 max. - -
Other Ti 0.7 max. Ti 0.7 max. Nb 1.0 max.
Mechanical Properties
Grade
Tensile Strength
(MPa) min
Yield Strength
0.2% Proof (MPa)
min
Elongation
(% in 50mm) min
Hardness
Rockwell B
(HR B) max
Brinell (HB) max
321 515 205 40 95 217
321H 515 205 40 95 217
347 515 205 40 95 201
Physical Properties
Grade
Density
(kg/m3)
Elastic
Modulus
(GPa)
Mean Coefficient of Thermal
Expansion
(μm/m/°C)
Thermal
Conductivity
(W/m.K)
Specific
Heat 0-100°
C (J/kg.K)
Electrical
Resistivity
(nΩ.m)
321 8027 193 16.6 17.2 18.6 16.1 22.2 500 720
Grade Specification Comparison
Grade UNS No
Old British
BS
GOST
Euronorm
No
Name Swedish SS Japanese JIS
321 S32100 321S31 08KH18N10T 1.4541 X6CrNiTi18-10 2337 SUS 321
321H S32109 321S51 12KH18N10T 1.4878 X10CrNiTi18-10 - SUS 321H
347 S34700 347S31 - 1.455 X6CrNiNb18-10 2338 SUS 347
Typical uses include annealing covers, high-temperature tempering equipment, diesel and heavy duty automotive
exhaust systems, firewalls, stack liners, boiler casings, welded pressure vessels, jet aircraft components, radiant
superheaters, bellows and oil refinery equipment.

Heat pipe with fins thermal analysis

Empfohlen

Empfohlen

Weitere ähnliche Inhalte

Was ist angesagt?

Was ist angesagt? (20)

Ähnlich wie Heat pipe with fins thermal analysis

Ähnlich wie Heat pipe with fins thermal analysis (20)

Kürzlich hochgeladen

Kürzlich hochgeladen (20)

Heat pipe with fins thermal analysis