Numerical Analysis for Heat Transfer Augmentation in a Circular Tube Heat Exchanger Using a Triangular Perforated Y-Shaped Insert
Abstract
:1. Introduction
2. Geometry of Insert
3. Mathematical Calculations
4. Modelling and Grid Independence Test
4.1. Mathematical Modelling
4.2. Numerical Model
4.3. Grid Independence Test (GIT)
4.4. Model Validation
5. Results
5.1. Effect on Nu
5.2. Effect on f
5.3. Effect on TPF
6. Comparison with Previous Work
7. Conclusions
- The results show that increasing Re provides better heat transmission characteristics for higher perforated inserts along with decreasing the friction factor. Furthermore, a lower range of Reynolds number gives a higher value of TPF.
- The Nu varies between 60 to 210 with an increase in PI from 0% to 30% under the range of Reynolds number between 3000 and 21,000, whereas the friction factor varies between 0.05 and 0.51 with an increase in PI from 0% to 30% under the range of Reynolds number between 3000 and 21,000.
- The maximum TPF found is 3.25 at perforation index = 30% and Re = 3000. The enhancement in heat transmission is found 5.84 times better compared to the simple plain tube.
- It has also been observed from the study that this type of insert may be useful for industrial application because it significantly augments heat transmission by more than of five times and the thermal performance is enhanced by more than three times. The present study showed better heat transmission characteristics as compared to other research in the same range of Reynolds number.
Author Contributions
Funding
Conflicts of Interest
Nomenclature
A | Area of circular pipe (m2) |
Cp | Specific heat of air (Jkg−1 K−1) |
D | Test segment diameter (m) |
f | Friction factor for rough tube |
fs | Friction factor for simple plain tube |
h | Average convective heat transfer coefficient (W m−2 K−1) |
k | Thermal conductivity of air (Wm−1 k−1) |
L | Test section length (m) |
m | Air flow rate (kgs−1) |
Nu | Nusselt number |
Nus | Nusselt number for simple plain tube |
PA | Perforated area of insert (m2) |
Pr | Prandtl number |
Q | Heat flux (W) |
Qair | Heat carried by air (W) |
Qconv | Heat transfer by convection (W) |
Re | Reynolds number |
TA | Total area of Y-shaped insert (m2) |
Tfm | Fluid mean temperature (K) |
Ti | Air temperature at inlet (K) |
To | Air temperature at outlet (K) |
Twm | Wall mean temperature (K) |
v | Velocity of air (ms−1) |
ΔP | Pressure difference (between inlet and outlet of the test segment) (Pa) |
Abbreviations | |
TPF | Thermal performance factor |
PI | Perforation index (PA/TA) |
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Boundary Condition | Values |
---|---|
Air temperature at inlet (K) | 300 |
Inlet velocity (m/sec) | 5.18, 4.44, 3.706, 2.963, 2.22, 1.48, 0.7409 |
Heat flux (W/m2) | 1000 |
Ambient Pressure (atm) | 1 |
Density (kg/m3) | 1.225 |
Specific heat (J/kg−K) | 1006.53 |
Viscosity (kg/m−s) | 1.7894 × 10−5 |
Thermal conductivity (W/m−K) | 0.0242 |
Grid Number | Nu | f | ||
---|---|---|---|---|
50, 258 | 35.87 | - | 0.1486 | - |
98, 547 | 48.27 | 0.2569 | 0.1857 | 0.2001 |
3, 54, 782 | 60.12 | 0.1971 | 0.2106 | 0.1181 |
8, 84, 704 | 62.48 | 0.0378 | 0.2302 | 0.0852 |
15, 24, 877 | 62.49 | 0.0002 | 0.2413 | 0.0459 |
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Pandey, L.; Singh, S. Numerical Analysis for Heat Transfer Augmentation in a Circular Tube Heat Exchanger Using a Triangular Perforated Y-Shaped Insert. Fluids 2021, 6, 247. https://doi.org/10.3390/fluids6070247
Pandey L, Singh S. Numerical Analysis for Heat Transfer Augmentation in a Circular Tube Heat Exchanger Using a Triangular Perforated Y-Shaped Insert. Fluids. 2021; 6(7):247. https://doi.org/10.3390/fluids6070247
Chicago/Turabian StylePandey, Lokesh, and Satyendra Singh. 2021. "Numerical Analysis for Heat Transfer Augmentation in a Circular Tube Heat Exchanger Using a Triangular Perforated Y-Shaped Insert" Fluids 6, no. 7: 247. https://doi.org/10.3390/fluids6070247