Numerical Study of Heat Transfer Enhancement of Internal Flow Using Double-Sided Delta-Winglet Tape Insert
Abstract
:1. Introduction
2. Physical Model
3. Numerical Technique
4. Results and Discussion
4.1. Verification of the Numerical Results
4.2. Effect of Attack Angle on Heat Transfer Characteristic
4.3. Effect of Attack Angle on Fluid Flow Characteristic
4.4. Thermal Performance Factor
4.5. Comparison of Obtained Results with the Experimental Results
5. Conclusions
- The Nusselt number (Nu), friction factor (f), and thermal performance factor (η) of the PDWVGs with various attack angles are found to be higher than those of the smooth tube. As the attack angle increases, Nu, f, and η also increase.
- The highest increase in the Nusselt number and friction factor, respectively, was found to be up to 269% and 10.1 times higher than those of the smooth tube. These results have been sufficiently confirmed through experiments.
- It was revealed that the thermal performance factor approaches a value of 1.1.
- The heat transfer mechanism was clearly elucidated using the streamline and temperature distribution at the cross sections.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
Nomenclature
c | chord length of the delta-wing [m] |
Cp | specific heat capacity at a constant pressure [J/kg⋅K] |
d | diameter of inner tube [m] |
D | diameter of outer tube [m] |
f | friction factor |
h | average convective heat transfer coefficient of the plain tube (W/m2⋅K) |
k | thermal conductivity [W/m·K] |
keff | effective thermal conductivity [W/m·K] |
L | length of the inner tube [m] |
Nu | average Nusselt number |
p | pitch of the delta-wing [m] |
Pr | Prandtl number |
Re | Reynolds number |
t | thickness of the aluminum strip [m] |
T | temperature [K] |
u | velocity of hot water in the inner tube [m/s] |
w | width of the delta-wing [m] |
W | width of the aluminum strip [m] |
Greek symbols | |
α | angle of attack [°] |
αP | pressure drop across the inner tube [Pa] |
η | thermal performance factor |
μ | dynamic viscosity [kg/m·s] |
ρ | density of hot water [kg/m3] |
Subscripts | |
i | inner |
o | outer |
p | plain tube |
t | tube with T-Ws |
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Parameter | Unit | Value |
---|---|---|
Inner tube | ||
| mm mm mm | 14.3 15.8 2110 |
Outer tube | ||
| mm mm mm | 24.3 25.4 2110 |
Fluid | Temperature [K] | cp [kJ/kg⋅K] | ρ [kg/m3] | μ [kg/m⋅s] | k [W/m⋅K] | Pr |
---|---|---|---|---|---|---|
Hot water | 333.15 | 4.185 | 983.3 | 4.67(10–4) | 0.654 | 2.99 |
Cold water | 300.15 | 4.178 | 997 | 8.52(10–4) | 0.613 | 5.81 |
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Wijayanta, A.T.; Aziz, M.; Kariya, K.; Miyara, A. Numerical Study of Heat Transfer Enhancement of Internal Flow Using Double-Sided Delta-Winglet Tape Insert. Energies 2018, 11, 3170. https://doi.org/10.3390/en11113170
Wijayanta AT, Aziz M, Kariya K, Miyara A. Numerical Study of Heat Transfer Enhancement of Internal Flow Using Double-Sided Delta-Winglet Tape Insert. Energies. 2018; 11(11):3170. https://doi.org/10.3390/en11113170
Chicago/Turabian StyleWijayanta, Agung Tri, Muhammad Aziz, Keishi Kariya, and Akio Miyara. 2018. "Numerical Study of Heat Transfer Enhancement of Internal Flow Using Double-Sided Delta-Winglet Tape Insert" Energies 11, no. 11: 3170. https://doi.org/10.3390/en11113170