Accepted Manuscript Numerical simulation of heat transfer enhancement in a plate-fin heat exchanger using a new type of vortex generators Mohammad Samadifar, Davood Toghraie PII: DOI: Reference:
S1359-4311(17)36306-8 https://doi.org/10.1016/j.applthermaleng.2018.01.062 ATE 11716
To appear in:
Applied Thermal Engineering
Received Date: Revised Date: Accepted Date:
29 September 2017 28 November 2017 18 January 2018
Please cite this article as: M. Samadifar, D. Toghraie, Numerical simulation of heat transfer enhancement in a platefin heat exchanger using a new type of vortex generators, Applied Thermal Engineering (2018), doi: https://doi.org/ 10.1016/j.applthermaleng.2018.01.062
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Numerical simulation of heat transfer enhancement in a plate-fin heat exchanger using a new type of vortex generators Mohammad Samadifar1, Davood Toghraie1* 1
Department of Mechanical Engineering, Khomeinishahr Branch, Islamic Azad University, Khomeinishahr, Iran
*
Corresponding author: Davood Toghraie, Department of Mechanical Engineering, Islamic Azad University, Khomeinishahr Branch, Khomeinishahr 84175-119, Iran. Email:
[email protected]
Abstract In this work, the effect of different vortex generators on fin-plate heat exchanger performance with a triangular channel cross-section is examined. The analysis is done using finite volume method. The effects of vortex generators in a channel are investigated by consideration of channel temperature and heat transfer coefficient. Six different vortex generators including a simple rectangular vortex generator (SRW), rectangular trapezius vortex generator (RTW), angular rectangular vortex generator (ARW), Wishbone vortex generators (WW), intended vortex generator (IVG) and wavy vortex generator (WVG) have been investigated. The observations suggest that simple rectangular vortex generator increases the heat transfer of finplate heat exchanger more than other models. This vortex generator increases heat transfer in the heat exchanger by 7%. However, vortex generators increase the pressure drop in heat exchanger. In addition, by increasing the height of the vortex generators the heat transfer rate is increased and the best angle of attack for the installation of vortex generator is 45 o. Keywords: Heat exchanger, Fin-plate, Vortex generator, Heat transfer, Performance.
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1. Introduction Heat transfer enhancement is required in industries. Different techniques such as fins, ribs, dimpled surfaces and protruding surfaces that generate vortices are used for heat transfer enhancement. There are two different methods for heat transfer enhancement: Active methods and passive methods. Using vortex generators for heat transfer enhancement is a passive method. The enhancement of heat transfer by using vortex generator arrays is the subject of growing importance in industrial applications; the studies carried out in order to cover the enhancement in heat transfer by using of vortex generators in all applications and the effect of configurations for heat exchangers. He et al. [1] studied the heat-transfer enhancement by punched winglet-type vortex generator arrays in fin-and-tube heat exchangers. They concluded that the vortex generator arrays generate more vortices and the vortices influence each other which weaken the swirling movement of the fluid, especially for the continuous small winglet array. Habchi et al. [2] investigated enhancing heat transfer in vortex generator-type multifunctional heat exchangers. They showed that the vortex generator arrays greatly enhance the heat transfer with a small increase in the pressure drop. Delac et al. [3] investigated the heat transfer enhancement in a fin and tube heat exchanger using vortex generators. They found that in the range of this study, the variation of these parameters can result in the increase of heat transfer but with a penalty of pressure drop. Xia et al. [4] simulated the heat transfer enhancement by longitudinal vortex generators in dimple heat exchangers. They found that the thermal performance of the longitudinal vortex generators is higher than that of the dimple cases with similar flow characteristics. Aliabadi et al. [5] studied performance of a plate-fin heat exchanger with vortex-generator channels. They found that heat transfer coefficient and pressure drop values enhance as the wings height, longitudinal wings
2
pitch, and transverse wings pitch decrease and the wings width, channel length, and wings attack angle increase. Li et al. [6] simulated the flow and heat transfer of fin-and-tube heat exchanger with longitudinal vortex generators. They observed that the delta winglet with angle of attack of 45o has the best overall performance than the other angles of attack in delta winglets configurations. Wang et al. [7] investigated the semi-dimple vortex generator for fin-and-tube heat exchangers. They found that the friction factors for the opposite air flow operation is lower than that of normal operation, especially in low Reynolds number region. Sinha et al. [8] investigated enhancement of heat transfer in a fin-tube heat exchanger using rectangular winglet type vortex generators. They found that significant improvement in the heat transfer performance due to the nozzle-like flow passages created by the winglet pair and the region behind the circular tube which promote accelerating flow. Aliabadi et al. [9] studied the vortex-generator fitted in tubular heat exchangers with dilute Cu–Water nanofluid flow. They concluded that that the winglets-width ratio, winglets-pitch ratio, and winglets-length ratio have strong effects on the heat transfer and pressure drop. Song et al. [10] obtained a relationship between secondary flow intensity and heat transfer intensity in a heat exchanger with vortex generators. Datta et al. [11] investigated the heat transfer in microchannel using inclined longitudinal vortex generator. They found that the size of vortices in a microchannel increases with increase in both Re and LVG angle with respect to the axial direction. Ahmed et al. [12] simulated turbulent heat transfer and nanofluid flow in a triangular duct with vortex generators. They observed high heat transfer and low pressure drop by using nanofluid and vortex-generator simultaneously. Li et al. [13] investigated the application of vortex generators to heat transfer enhancement of a pin-fin heat sink. They concluded that the heat transfer of the heat sink is higher when the vortex generators are installed against the middle of the heat sink on both sides of it. Song et al. [14] investigated
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the effect of geometric size of curved delta winglet vortex generators and tube pitch on heat transfer characteristics of fin-tube heat exchanger. They found that the change of fin pitch has less effect on Colburn factor while friction factor is obviously affected by the change of fin pitch. Wijayanta et al. [15] studied heat transfer enhancement of internal flow by inserting punched delta winglet vortex generators with various attack angles. Their results revealed that the punched delta winglet vortex generators in a tube provided considerably higher heat transfer coefficient than the tube without the insert through pressure loss was also increased. Esmaeilzadeh et al. [16] compared the simple and curved trapezoidal longitudinal vortex generators for optimum flow characteristics and heat transfer augmentation in a heat exchanger. Their results showed that curved trapezoidal winglet pair has a lower pressure drop and a better overall performance compared to trapezoidal winglet pair. In this work, the effect of different vortex generators on fin-plate heat exchanger performance with a triangular channel cross-section is examined. The analysis is done using finite volume method. The effects of vortex generators in channel are investigated. Six different vortex generators have been investigated.
2- Governing equations, geometry and boundary conditions 2-1 Governing equations The governing equations include continuity, momentum and energy equations in Cartesian coordinate are defined as follow [17, 18]. The second order discretization [19] has been used for all parameters. The k SST turbulence model (Shear stress transport k ) has been used for modeling the turbulent flow. These equations are defined such as follow: Continuity equation: 4
ui 0 X i
(1)
Momentum equation: P ui u j X j X i X j
u u j 2 u ij i i X j X i 3 X j
u /i u / j X j
(2)
Energy equation:
ui E P X i X j
Cpt Prt
T ui i j X j
0 eff
(3)
eff is the deviation stress tensor which is defined
In the above equation, E is the total energy, ij as follow,
E CpT ( P / ) u 2 / 2
ij
eff
eff
(4)
u j ui 2 ui ij eff X X 3 X i j j
(5)
The transport equation for shear stress transport model of k is as follow,
k ui X i X j
k k X j
k ui X i X j
Gk Yk Sk
X j
(6)
G Y D S
(7)
Where, G k is the turbulent kinetic energy caused by average velocity gradients and G is the indicator of this term from .
5
G k min Gk ,10 *k
(8)
u j Gk u / iu / j X i G
G t k
(9)
In the above equation, t is the turbulent cinematic viscosity and * is constant of model and the amount of α is calculated from following equation,
* 0
Ret / R
1 Ret / R
(10)
The amount of R 2.95 and α is defined as follow,
F1 ,1 (1 F1 ) ,2
(11)
i ,1 2 ,1 * ,1 *
(12)
,2
(13)
i ,2 2 * ,2 *
0.41, i 0.072, 1.0 In equations (6) and (7), the terms of and k are the effective diffusions of k and and are defined as follow, t k t
(14)
k
(15)
The terms of and k are the indicators of turbulent Prandtl number in ( k ) model and are defined as follow,
1 F1 / ,1 (1 F1 ) / ,2
k
1 F1 / k ,1 (1 F1 ) / k ,2
6
(16) (17)
t is the turbulent viscosity and is defined as,
t *
k
(18)
* is the damper of turbulent viscosity and is defined by the following equation,
*
*
* 0
Ret / R k
1 Ret / R k
(19)
* * 1.0 Ret k / , Rk 6, *0 i / 3, i 0.072 The F1 is equal with,
F1 tan(14 )
(20)
k 500 4 k 1 min max , , 2 2 D y 0.09 y y ,2
(21) (22)
1 1 k D max 2 ,1010 ,2 X j X j
In equation (21), D , the positive part is diffusion term in cross section. Y k and Y are the indicators of k and losses and according to turbulence, are defined as follow,
Yk *k
(23)
Y 2 , * & are constants
(24)
i F1i,1 (1 F1)i,2
(25)
7
D indicates the penetrating term in cross section, while S k and S are the possible conditions
of source, specifically, D is equal with,
D 2(1 F1 ) ,2
1 k X j X j
(26)
According to the previous studies about the two-equation models [20] k SST method has been used for simulation the flow and heat transfer. The model constants are summarized in table 1.
Table 1 Constant shear stress transport turbulence model (SST model) of k
k ,1 1.176
k ,2 1
,1 2
,2 1.68
1 0.31
i ,1 0.075
i ,2 0.0828
* 1
0.52
* 0.09
i 0.072
0 1.9
R 8
Rk 9
R 2.95
* 1.5
k 2
2
In this study, the following dmensionless parameters are used,
T T Tw T
X
Re
x H
(27)
U H
CP
P 1 U 2 2
Where Re is Reynolds number, C P is pressure drop coefficient, is dimensionless bulk temperature and
is dimensionless distance along the channel.
2-2 Geometry
8
The schematic of cross-flow fin-plate heat exchanger is shown in figure 1. In this heat exchanger, hot and cold fluids enter perpendicularly and exit after heat exchange with each other. In this heat exchanger, with the help of blades, channels with triangular cross-section have been created to pass the cold and warm fluids. These channels are shown in figure 1with the symbol . In this study, the effects of the vortex generator placement on the
and
blades have been investigated. With regard to the symmetry of the problem, one half of the channel, namely
, has been selected as the fluid domain. In this domain, the vortex
generator will be located on the blade
.
Fig. 1. Schematic diagram of the physical model
Six different shapes for vortex generators (shown in figure 2) include, respectively, the following: a
) Simple rectangular winglet (SRW) 9
b
) Rectangular trapezoidal winglet (RTW)
c
) Angular rectangular winglet (ARW)
d
) Wishbone winglet (WW)
e
) Intended vortex generator (IVG)
f
) Waved vortex generator (WVG)
The dimensions of the vortex generators are specified in figure 3. Dimensions are chosen so that the space occupied by all produces is equal to a square of 15mm×15mm. The height of the vortex generators is also assumed to be 5mm, in order to compare the performance of different wing geometries. The length of the channel is L=160mm and its height (AC) is 20mm. The geometry of the vortex generator generates a cut from the inside of the fluid domain (figure 4). The fluid domain is meshed with the help of hexagonal elements with a size of approximately 1mm. The grid pattern is shown in figure 4. Generally, for the sample without vortex generator, about 39000 nodes and 32000 cells were created. In models with vortex generator, for the meshing of the area around the vortex generator, pyramidal tetrahedron cells are used. The grid structure of the area surrounding the vortex generator is shown in figure 4. Due to the change in the type of element and size of the sides, the elements produced around the vortex generator are approximately eight times smaller than the other elements.
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Fig 2. Six different shapes for vortex generators a) SRW, b) RTW, c) ARW, d) WW, e) IVG, f) WVG
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a Fig.3 The dimensions of the vortex generators (mm) a) SRW, b) RTW, c) ARW, d) WW, e) IVG, f) WVG
12
Fig. 4 meshing area around vortex generator
2-3 Boundary conditions The triangular ABC section is selected as the inlet (Figure 5). According to the Reynolds number equation, the inlet velocity is considered to be U =146m/s to make the Reynolds number equal to Re=200. The fluid inlet temperature is also considered to be 300K. At the
, the boundary
condition of symmetry has been created (Figure 5). The boundary condition of symmetry is applied both to fluid velocity and to fluid temperature. The cross section
is considered as
the fluid outlet (Figure 5). At this point, it is assumed that the fluid pressure is constant and equal to the atmospheric pressure. In sections
and
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the no-slip boundary condition and
constant temperature have been applied. Wall temperature Tw=500K is assumed. The two conditions are also applied to vortex generators.
Fig. 5 Boundary conditions
2-4 Thermophysical properties of working fluids
Thermophysical properties of working fluid (Air) are given in table 2. Table 2. Thermophysical properties of fluid (Air) Cp (J/kg K)
ρ (kg/m3)
k (W/m K)
μ (kg/m.s)
1006.43
1.225
0.0242
1.789 10-5
14
2-5 Validation Figure 6 compares the temperature diagram versus distance along the heat exchanger channel with Ref. [21]. The diagram shows that there is a good agreement between the results of this model and the Ref. [21]. Based on both graphs, the bulk temperature of the channel is increasing from inlet to outlet. As the end of channel, the temperature difference between the fluid and the wall decreases and the heat transfer is reduced. The outlet bulk temperature of the channel is 0.85 [21] and outlet bulk temperature of this model is equal to 0.862. So, the maximum difference is about 1.3%.
Fig. 6 Comparison of the balk temperature versus the distance from the channel inlet and the Ref. [21]
3- Results and Discussion Figure 7 shows the effect of vortex generators on the bulk temperature versus distance from the channel inlet. Temperature variations in the channel with different vortex generators are compared with the channel without any vortex generators. Results show that, all vortex 15
generators enhance the heat transfer. According to this diagram, the simple rectangular vortex generator causes the greatest increase in heat transfer.
Fig. 7 the effect of vortex generators on the bulk temperature versus distance from the channel inlet
Figure 8 shows the effect of vortex generators on the local Nusselt number. All vortex generators increased the heat transfer coefficient and, consequently, the Nusselt number. Maximum heat transfer was observed in the channel with a SRW. Based on this diagram, the use of a RTW or ARW the local Nusselt number at some points, but ultimately increased the overall heat transfer of the channel.
16
10 No VG SRW RTW ARW WW IVG WVG
Nu
8
6
4
2
1
2
3
4
5
6
7
8
X Fig. 8 The effect of vortex generators on the local Nusselt number
It is worth noting that, at X=1, the Nusselt number for channels with vortex generator has the greatest difference compared to the channel without vortex generator. This is precisely the region where vortexes are formed. After that, with a drop in the Nusselt number, the heat transfer coefficient of all the channels approached a constant value. However, in some channels (such as a channel with a RTW), the heat transfer coefficient is more than the simple channel along the whole length of the channel. It can be said that the major part of heat transfer occurs in the regions where the vortexes are present. The flow in the channel is uniform in areas far from the vortex generators, reducing the heat transfer coefficient. Figure 9 shows the pressure drop coefficient versus distance from the channel inlet. According to figure 9, all types of vortex
17
generators in the channel increase the pressure drop. The formation of vortexes causes the flow to diverge from its main path, which is the main contributor to the increased pressure drop in the channel with the vortex generator. According to this figure, pressure drop is maximum in the channel with RTW. In fact, the greater is the effect of the vortex generator on the heat transfer, the greater is the pressure drop. 7
6
5
CP
4
3 SRW RTW ARW WW IVG WVG No VG
2
1
0
0
2
4
6
8
10
X Fig. 9 Pressure drop coefficient versus distance from the channel inlet
A coefficient known as the performance evaluation criterion (PEC) is used to simultaneously examine the increase in heat transfer and pressure drop. The performance evaluation criterion (PEC) parameter is defined as follows [18],
18
(28)
3.5
Nu f PEC Nu 0 f 0 Where Nu is average Nusselt number and f is average friction factor. The index
0
also represents
a simple channel without a vortex generator. A greater PEC values means the system is more economical. The PEC for various vortex generators is shown in table 3. This table shows that the rectangular vortex generator with a PEC of 1.444 has the best performance and is the most efficient vortex generator.
Table 3 PEC values for various vortex generators PEC
Vortex generator type
1.44
SRW
1.14
RTW
0.97
IRW
1.04
WW
1.4
IVG
1.24
WVG
Since the SRW had the best PEC, a SWR with a length of 16 mm and a height of 5 mm with the angles of attack of 0°, 15°, 30°, 45°, 60°, 75°, and 90° are studied here. As can be seen in figure 10, vortex generators at all angles increased the average bulk temperature along the channel and thereby enhanced the heat transfer. Even though a vortex generator with a zero angle of attack does not generate any vortexes, it has a positive effect on heat transfer. The reason is that, 19
although there are no vortexes present, the vortex generator acts like a fin, increasing the heat transfer surface. The diagram clearly shows that maximum heat transfer corresponds to the channel with the vortex generator with an angle of 45°. As angle of attack deviates from 45°, the channel output temperature decreases.
Fig. 10 the effect of angles of attack on the bulk temperature versus distance from the channel inlet for a simple rectangular vortex generator (SWR)
Figure 11 shows the effect of a SWR with different angles of attack on the Nusselt number in the channel. The diagram shows that the vortex generator with an angle of attack of 45° brings about the highest increase in the Nusselt number and the heat transfer coefficient. The heat transfer coefficient for a channel without vortex generators and a channel with zero vortex generators is 20
approximately the same. The lowest convective heat transfer coefficient is observed in the channel with a 90° vortex generator. In this vortex generator, the greatest heat transfer occurs at the entrance of the channel and before reaching the vortex generator.
Fig. 11 Effect of a SWR with different angles of attack on the Nusselt number in the channel
It is worth noting that in channels with 90°, 75°, and 60° vortex generators, the Nusselt number and the local heat transfer coefficient are greatest at the beginning of the channel. But as distance from the location of the vortex generator increases, the heat transfer in the three channels drops sharply. In fact, the effect of the vortex generator on the flow is lifted at higher angles of attack, reducing the life of generated vortexes. This is due to the fact that longitudinal component of the 21
vortex generator decreases with increasing the angle of attack. While selecting the angle of attack for a vortex generator, it should be noted that the near-zero angles of attack reduce the likelihood of generation of a vortex in the flow, while the angles of attack of close to 90° create vortexes that disappear faster away from the vortex generator location. For the geometry considered in this section, the 45° angle of attack yielded the best performance and is selected as the best angle of attack. Figure 12 shows the temperature at the channel outlet. This figure suggests that the best angle of attack for a vortex generator is between 40° to 45°, confirming the descriptions in the previous section. Reduced angle of attack of the vortex generator reduces the number of vortexes, reducing the effects of the vortex generator in enhancing the heat transfer. The diagram also shows that increase in the angle of attack of the vortex generator reduces its heat transfer enhancement effect. It should be noted that the vortex generator increases the heat transfer through two independent mechanisms. The first mechanism is the generation of vortexes, which increases the heat transfer coefficient. The second mechanism is similar to the function of a fin, which increases the heat transfer surface. By increasing the angle of attack more than 45°, the vortex generator has a weaker performance, which reduces the heat transfer.
22
Fig. 12 the temperature at the channel outlet
The diagram of pressure drop coefficient for the channel with the rectangular vortex generator for different angles of attack is shown in figure 13. Increase in angle of attack always increases the pressure drop. Therefore, by increasing the angle of attack of the vortex generator from zero to about 45°, both the heat transfer and the pressure drop increase. However, increase in the angle of the attack from 45° to 90°, despite reducing the heat transfer increased the pressure drop, which is not desirable.
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Fig. 13 Pressure drop coefficient for the channel with the rectangular vortex generator for different angles of attack
The PEC for various angles of attack is shown in figure 14. This figure shows that the vortex generator with an angle of attack of 30° to 60° has the best performance and is more cost effective than other cases. Given that simple rectangular vortex generator has the best performance at the angle of 45°, the performance of this vortex generator with heights of 1, 2, 3, 4, 5 and 6 mm was examined at the angle of 45°.
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Fig. 14 the PEC for various angles of attack
Figure 15 shows the effect of vortex generators height on the bulk temperature, that the heat transfer has increased for channels with higher vortex generators. As seen in these two graphs, the vortex generator does not have a significant effect on heat transfer up to a height of 3 mm. However, for a vortex generator with a height of 4 mm or more, the heat transfer is increased, and the higher the generator, the greater the heat transfer. Of course, the space available for the generator should also be taken in to consideration when selecting the height of the vortex generator.
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Fig. 15 the effect of vortex generators height on the bulk temperature
Figure 16 shows that increase in channel height increases Nusselt number and the heat transfer coefficient. The graphs suggest that a minimum height for vortex generator is required for having a significant effect on the heat transfer. To further examine this, the bulk temperature at the channel outlet is plotted in figure 17 in terms of the vortex generator height. The graph is almost smooth at first. As the height increases to 3 mm or more, the effect of the vortex generator in the heat transfer becomes more evident.
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Fig. 16 the effect of vortex generators height on the Nusselt number
Fig. 17 the bulk temperature at the channel outlet
27
As shown in figure 18, increase in the heat transfer rate increases the pressure drop. Increased height of the vortex generator reduces the fluid passage area, increasing the pressure drop. Figure 19 shows PEC for vortex generators with different heights. According to this figure, higher vortex generators perform better.
8
CP
6
4
Hw =1mm Hw=2mm Hw =3mm Hw=4mm Hw =5mm Hw =6mm no VG
2
0
0
2
4
6
8
X Fig. 18 Effect of vortex generator height on pressure drop coefficient
28
1.7 1.6 1.5 1.4
PEC
1.3 1.2 1.1 1 0.9 0.8 0.7
1
2
3
4
5
6
7
HW Fig. 19 PEC for vortex generators with different heights
Figure 20 shows the bulk temperature along the two channels, one of which has a vortex generator and the other with three vortex generators. The channel with three vortex generators caused a higher increase in fluid temperature, with each vortex generator independently increasing the heat transfer.
29
Fig. 20 the bulk temperature along the two channels: one of which has a vortex generator and the other with three vortex generators
4- Conclusion In this paper, the effect of different vortex generators on fin-plate heat exchanger performance with a triangular channel cross-section is examined. Six different vortex generators have been investigated. Following results were deduced:
The observations suggest that simple rectangular vortex generator increases heat transfer of fin-plate heat exchanger more than other models.
Simple rectangular vortex generator increases heat transfer in sample heat exchanger by 7%. 30
Increasing the height of the vortex generators increases its effect on improving the heat transfer.
The best angle of attack for the installation of vortex generator is 45 o.
The extension of this paper for CFD simulation according our previous works [22-47] affords engineers a good option for CFD simulation. References [1] Y.L. He, H. Han, W.Q. Tao, Y.W. Zhang, Numerical study of heat-transfer enhancement by punched winglet-type vortex generator arrays in fin-and-tube heat exchangers, International Journal of Heat and Mass Transfer 55 (2012) 5449–5458 [2] Charbel Habchi, Serge Russeil, Daniel Bougeard, Jean-Luc Harion, Thierry Lemenand, Dominique Della Valle, Hassan Peerhossaini, Enhancing heat transfer in vortex generator-type multifunctional heat exchangers, Applied Thermal Engineering 38 (2012) 14-25 [3] Boris Delac, Anica Trp, Kristian Lenic, Numerical investigation of heat transfer enhancement in a fin and tubeheat exchanger using vortex generators, International Journal of Heat and Mass Transfer 78 (2014) 662–669 [4] H.H. Xia, G.H. Tang, Y. Shi, W.Q. Tao, Simulation of heat transfer enhancement by longitudinal vortex generators in dimple heat exchangers, Energy 74 (2014) 27-36 [5] M. Khoshvaght-Aliabadi, S. Zangouei, F. Hormozi, Performance of a plate-fin heat exchanger with vortex-generator channels: 3D-CFD simulation and experimental validation, International Journal of Thermal Sciences 88 (2015) 180-192 [6] Li Li, Xiaoze Du, Yuwen Zhang, Lijun Yang, Yongping Yang, Numerical simulation on flow and heat transfer of fin-and-tube heat exchanger with longitudinal vortex generators, International Journal of Thermal Sciences 92 (2015) 85-96 31
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[21] M. Gupta, K.S. Kasana, R. Vasudevan, “Heat Transfer
ugmentation in a Plate-Fin Heat
xchanger Using a Rectangular Winglet”, Heat Transfer-Asian Research, 39 (8), 2010 [22] Karimipour A. Alipour H. Akbari OA. Semiromi DT. Esfe MH., Studying the Effect of Indentation on Flow Parameters and Slow Heat Transfer of Water-Silver Nano-Fluid with Varying Volume Fraction in a Rectangular Two-Dimensional Micro Channel, Indian Journal of Science and Technology, 2016, 8, 2015 [23] Akbari OA. Karimipour A. Toghraie D. Karimipour A, Impact of ribs on flow parameters and laminar heat transfer of Water/Alumina nanofluid with different nanoparticle volume fractions in a three-dimensional rectangular microchannel, Adv Mech Eng, 2016; 7: 1–11 [24] Akbari OA. Karimipour A. Toghraie D. Safaei MR. Alipour M. Goodarzi H. and Dahari M. Investigation of Rib's Height Effect on Heat Transfer and Flow Parameters of Laminar Water- Al2O3 Nanofluid in a Two Dimensional Rib-Microchannel. Appl Math Comp, 2016, 290, 135–153 [25] Akbari OA. Toghraie D. Karimipour A. Numerical simulation of heat transfer and turbulent flow of Water nanofluids CuO in rectangular microchannel with semi attached rib. Adv Mech Eng. 2016; 8: 1–25 [26] Alipour H. Karimipour A. Safaei MR. Semiromi DT. Akbari OA., Influence of T-semi attached rib on turbulent flow and heat transfer parameters of a silver-Water nanofluid with different volume fractions in a three-dimensional trapezoidal microchannel. Physica E, 2016; 88: 60-76 [27] Nazari S. Toghraie D. Numerical simulation of heat transfer and fluid flow of Water-CuO Nanofluid in a sinusoidal channel with a porous medium. Physica E, 123; 87: 134-140
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[28] Sajadifar SA. Karimipour A. Toghraie D. Fluid flow and heat transfer of non-Newtonian nanofluid in a microtube considering slip velocity and temperature jump boundary conditions, European Journal of Mechanics-B/Fluids, 2017; 61: 25-32 [29] Aghanajafi A, Toghraie D. Mehmandoust B., Numerical simulation of laminar forced convection of Water-CuO nanofluid inside a triangular duct, Physica E, 2017: 85: 103-108 [30] Afrand M. Toghraie D. Karimipour A. Wongwises SA. Numerical Study of Natural Convection in a Vertical Annulus Filled with Gallium in the Presence of Magnetic Field, Journal of Magnetism and Magnetic Materials, 2017, 430: 22–28 [31] D Toghraie, Numerical thermal analysis of Water's boiling heat transfer based on a turbulent jet impingement on heated surface, Physica E, 84, 454-465, 2016 [32] S. Shareghi, D. Toghraie, Numerical Simulation of Blood Flow in Healthy Arteries by Use of the Sisko Model, Computational Thermal Sciences: An International Journal 8 (4), 2016 [33] Karimipour A. Esfe MH. Safaei MR. Semiromi DT. Jafari S. and Kazi SN. Mixed convection of Copper–Water nanofluid in a shallow inclined lid driven cavity using the lattice Boltzmann method. Physica A: Statistical Mechanics and its Applications. 2014, 402: 150-168 http://dx.doi.org/10.1007/s10973-016-5436-4. [34] Qumars Gravndyan, Omid Ali Akbari, Davood Toghraie, Ali Marzban, Ramin Mashayekhi, Reza Karimi, Farzad Pourfattah, The effect of aspect ratios of rib on the heat transfer and laminar water/TiO 2 nanofluid flow in a two-dimensional rectangular microchannel, Journal of Molecular Liquids 236, 254-265, 2017 [35] Heydari M. Toghraie D. Akbari OA. The effect of semi-attached and offset mid-truncated ribs and Water/TiO2 nanofluid on flow and heat transfer properties in a triangular microchannel. Therm Sci Eng Prog. 2017; 2: 140–150
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[36] Pourfattah F. Motamedian M. Sheikhzadeh Gh. Toghraie D. Akbari OA. The numerical investigation of angle of attack of inclined rectangular rib on the turbulent heat transfer of WaterAl2O3 nanofluid in a tube. Int J Mech Sci. 2017;131–132: 1106–1116 [37] Sarlak R. Yousefzadeh Sh. Akbari OA, Toghraie D, Sarlak S. assadi F. The investigation of simultaneous heat transfer of water/Al2O3 nanofluid in a close enclosure by applying homogeneous magnetic field. Int J Mech Sci. 2017;133:674–688 [38] Mashayekhi R. Khodabandeh E. Bahiraei M. Bahrami L. Toghraie D. Akbari OA. Application of a novel conical strip insert to improve the efficacy of water–Ag nanofluid for utilization in thermal systems: A two-phase simulation. Energ Conv Manag. 2017:151:573–586 [39] Toghraie D. Davood Abdollah MM. Pourfattah F. Akbari OA, Ruhani B. Numerical investigation of flow and heat transfer characteristics in smooth, sinusoidal and zigzag-shaped microchannel with and without nanofluid. J Therm Anal Calorim, DOI 10.1007/s10973-0176624-6 [40] P Barnoon, D Toghraie, Numerical investigation of laminar flow and heat transfer of nonNewtonian nanofluid within a porous medium, Powder Technology 325, 78-91, 2018 [41] M Parsaiemehr, F Pourfattah, OA Akbari, D Toghraie, G Sheikhzadeh, Turbulent flow and heat transfer of Water/Al2O3 nanofluid inside a rectangular ribbed channel, Physica E: Lowdimensional Systems and Nanostructures 96, 73-84, 2018 [42] Karbasifar, Bijan, M Akbari, D Toghraie, mixed convection of Water-Aluminum oxide nanofluid in an inclined lid-driven cavity containing a hot elliptical centric cylinder, International Journal of Heat and Mass Transfer 116 (1), 1237-1249, 2018 [43] H Kavusi, D Toghraie, A comprehensive study of the performance of a heat pipe by using of various nanofluids, Advanced Powder Technology 28 (11), 3074-3084, 2018
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Research highlights
Effect of different vortex generators on heat exchanger performance is examined.
The analysis is done using finite volume method.
Six different vortex generators have been investigated.
Simple rectangular vortex generator increases heat transfer more than other.
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Graphical abstract
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