Modelling and Evaluation of the Thermohydraulic Performance of Finned-Tube Supercritical Carbon Dioxide Gas Coolers
Abstract
:1. Introduction
2. Methodology
3. Model Validation
4. Results
4.1. Local Thermohydraulic Performance
4.2. Influence of Refrigerant Mass Flow Rate
4.3. Comparison between 8 mm and 5 mm Coils Finned-Tube Gas Coolers
5. Conclusions
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
Nomenclature
A | area, m2 |
cp | specific heat, J/(kgK) |
C | heat capacity rate, W/K |
D | hydraulic diameter, m; diameter, m |
f | friction factor |
Fs | fin spacing, m |
G | mass flux, kg/(m2s) |
h | heat-transfer coefficient, W/(m2 K); specific enthalpy, J·kg−1 |
i | segment number |
j | tube number |
k | thermal conductivity, W/(mK); row number |
L | length, m |
m | exponent parameter |
mass flow rate, kg/s | |
N | total segment number |
NTU | number of transfer units |
Nu | Nusselt number |
p | pressure, Pa |
P | tube pitch |
Pr | Prandtl number |
Q | heat-transfer rate, W |
r | radius, m |
R | thermal resistance, K/W |
Re | Reynolds number |
ReDc | Reynolds number based on tube collar diameter |
Sh | height of slit, m |
Sn | spacing in normal direction, m; number of slit |
Sp | spacing in parallel direction, m |
Ss | breadth of a slit in airflow direction, m |
T | temperature, K |
U | overall heat-transfer coefficient, W/ (m2K) |
Δp | pressure drop, Pa |
x | refrigerant flow direction |
XL | parameter |
XM | parameter |
Greek letters | |
ρ | density, kg/m3 |
μ | dynamic viscosity, Pa·s |
ɛ | effectiveness |
η | efficiency |
δ | thickness, m |
Subscripts | |
a | air |
cal | calculation |
eq | equivalent |
f | fin |
i | segment number |
in | inlet |
l | longitudinal |
max | maximum |
min | minimum |
mod | modelling |
n | normal |
p | parallel |
ref | refrigerant |
t | transverse |
out | outlet |
w | wall |
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Operating Conditions | ||||||||
---|---|---|---|---|---|---|---|---|
Test | vair, in (m/s) | Tair, in (°C) | pref, in (bar) | Tref, in (°C) | (g/s) | ReDc, air, in | Reref, in | |
Gas Cooler A | ||||||||
No. 1 | 1.7 | 32.8 | 85.1 | 105.5 | 10.5 | 1373 | 96,764 | |
No. 2 | 2.0 | 32.8 | 84.2 | 99.2 | 10 | 1615 | 92,595 | |
No. 3 | 2.4 | 34.3 | 86.6 | 116.8 | 10.3 | 1921 | 93,345 | |
Gas Cooler B | ||||||||
No. 4 | 1.7 | 35.1 | 86.3 | 100.8 | 19 | 1355 | 17,468 | |
No. 5 | 2.0 | 35.2 | 86.5 | 104.6 | 21.5 | 1593 | 19,678 | |
No. 6 | 2.4 | 33.0 | 83.9 | 101.3 | 21 | 1936 | 19,375 | |
Results | ||||||||
Test | Δpair, exp (Pa) | Δpair, mod (Pa) | Tref, out, exp (°C) | Tref, out, mod (°C) | Tair, out, exp (°C) | Tair, out, mod (°C) | Qexp (kW) | Qmod (kW) |
Gas Cooler A | ||||||||
No. 1 | 26.6 | 26.9 | 33.2 | 32.83 | 36.9 | 36.8 | 2.4 | 2.46 |
No. 2 | 34.2 | 34.8 | 32.8 | 32.82 | 35.9 | 36.0 | 2.23 | 2.31 |
No. 3 | 41.4 | 46.6 | 34.9 | 34.31 | 37.2 | 37.1 | 2.4 | 2.43 |
Gas Cooler B | ||||||||
No. 4 | 13.9 | 17.6 | 35.3 | 35.38 | 38.7 | 38.5 | 4.1 | 4.12 |
No. 5 | 25.6 | 22.7 | 35.0 | 35.54 | 38.5 | 38.5 | 4.6 | 4.75 |
No. 6 | 27.6 | 30.4 | 33.0 | 33.15 | 35.9 | 35.9 | 4.65 | 4.94 |
Type | No | Dimension | Operating Condition |
---|---|---|---|
Gas cooler A | 1 | Do = 8 mm, Din = 6.64 mm, Sj = 25.4 mm, Sk = 22 mm, L = 1.6 m, 12 fins per inch | vair, in = 2.4 m/s (air, in = 0.8794 kg/s) |
2 | Do = 5 mm, Din = 4.5 mm, Sj = 15.875 mm, Sk = 13.75 mm, L = 1.6 m, 12 fins per inch | vair, in = 2.4 m/s | |
3 | Do = 5 mm, Din = 4.5 mm, Sj = 15.875 mm, Sk = 13.75 mm, L = 1.0 m, 12 fins per inch | vair, in = 2.4 m/s | |
4 | Same as gas cooler A 2 | air, in = 0.8794 kg/s | |
5 | Same as gas cooler A 3 | air, in = 0.8794 kg/s | |
Gas cooler B | 1 | Do = 8 mm, Din = 6.64 mm, Sj = 25.4 mm, Sk = 22 mm, L = 1.6 m, 12 fins per inch | vair, in = 2.4 m/s (air, in = 1.7662 kg/s) |
2 | Do = 5 mm, Din = 4.5 mm, Sj = 15.875 mm, Sk = 13.75 mm, L = 1.6 m, 12 fins per inch | vair, in = 2.4 m/s | |
3 | Do = 5 mm, Din = 4.5 mm, Sj = 15.875 mm, Sk = 13.75 mm, L = 1.0 m, 12 fins per inch | vair, in = 2.4 m/s | |
4 | Same as gas cooler B 2 | air, in = 1.7662 kg/s | |
5 | Same as gas cooler B 3 | air, in = 1.7662 kg/s |
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Chai, L.; Tsamos, K.M.; Tassou, S.A. Modelling and Evaluation of the Thermohydraulic Performance of Finned-Tube Supercritical Carbon Dioxide Gas Coolers. Energies 2020, 13, 1031. https://doi.org/10.3390/en13051031
Chai L, Tsamos KM, Tassou SA. Modelling and Evaluation of the Thermohydraulic Performance of Finned-Tube Supercritical Carbon Dioxide Gas Coolers. Energies. 2020; 13(5):1031. https://doi.org/10.3390/en13051031
Chicago/Turabian StyleChai, Lei, Konstantinos M. Tsamos, and Savvas A. Tassou. 2020. "Modelling and Evaluation of the Thermohydraulic Performance of Finned-Tube Supercritical Carbon Dioxide Gas Coolers" Energies 13, no. 5: 1031. https://doi.org/10.3390/en13051031