Cooling Performance Optimization of Direct Dry Cooling System Based on Partition Adjustment of Axial Flow Fans
Abstract
:1. Introduction
2. Models and Approaches
2.1. Physical Models
2.2. Mathematical Models and Methods
2.3. Mesh Independence and Experimental Validation
3. Results and Discussion
3.1. Temperature Contour
3.2. Mass Flow Rate of Air
3.3. Heat Rejection
3.4. Turbine Back Pressure
4. Conclusions
- (1)
- The inlet air temperature of upwind fans significantly reduced when increasing the rotational speed of the windward fans. The changes in the rotational speed of the leeward fans have little effects on the inlet air temperature. The improvements for 110-case 1 are the most conspicuous in all of the wind directions;
- (2)
- Generally speaking, increasing the rotational speeds of upwind fans is beneficial to the air flow rates under various wind conditions;
- (3)
- The optimal strategies under different meteorological conditions can be obtained from the comparison of heat rejections. In the wind directions of 90° and −90°, the optimal strategies are 110-case 1 and 110-case 3 at the low and high wind speeds, respectively. In the wind direction of 0° however, 110-case 2 always performs best whatever the wind speed is;
- (4)
- The turbine back pressures of the optimal strategies have improved when comparing with the original cases. The biggest drop in the turbine back pressure is 2.77 kPa in the wind direction of −90° at the wind speed of 12 m/s.
Author Contributions
Funding
Conflicts of Interest
Nomenclature
c | number of windward adjusted fans |
fn | polynomial coefficient of the pressure drop for the fan |
gn | polynomial coefficient for the tangential velocity |
h | convection heat transfer coefficient (W/m2/K) |
h’ | empirical convection heat transfer coefficient (W/m2/K) |
hn | polynomial coefficient for convection heat transfer coefficient |
H | height above the ground (m) |
kL | pressure loss coefficient |
L | thickness of the finned tube bundles (m) |
n | rotational speed of fan |
N | number |
p | pressure (Pa) |
P | shaft power |
q | heat flux (W/m2) |
Q | heat transfer rate (kW) |
r | the distance to the fan center |
rn | polynomial factor for pressure loss coefficient |
S | source term |
S’ | additional source term |
t | temperature (K) |
u | velocity (m/s) |
x | the percentage of actual rotational speed to rated speed |
Greek symbols | |
Γ | diffusion coefficient (m2/s) |
ρ | density (kg/m3) |
φ | dependent variable |
ε | improvement coefficient of heat rejection |
Subscripts | |
0 | original |
2 | outlet |
a | air |
B | back |
e | energy |
f | face velocity |
j | direction |
m | momentum |
s | steam |
v | volume |
w | wind |
z | z axis |
θ | peripheral direction |
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Parameter | Value |
---|---|
Diameter of axial flow fan (m) | 9.144 |
Apex angle of finned flat tube bundles (°) | 59.4 |
Major axis of base tube (m) | 0.219 |
Short axis of base tube (m) | 0.019 |
Length of fin (m) | 0.2 |
Height of fin (m) | 0.019 |
Thickness of fin (m) | 0.00025 |
Pitch of fin (m) | 0.0023 |
Height of ACC platform (m) | 45 |
Surface | Wind Condition | Type | Setting |
---|---|---|---|
windward surface | with wind | velocity inlet | u = uz, t = 290.15 K |
without wind | pressure inlet | p = 101.325 kPa, t = 290.15 K | |
leeward surface | with wind | pressure outlet | p = 101.325 kPa, t = 290.15 K |
without wind | pressure inlet | p = 101.325 kPa, t = 290.15 K | |
side surface | with wind | symmetry | ∂u/∂x = 0, ∂t/∂x = 0 or ∂u/∂y = 0,∂t/∂y = 0 |
without wind | pressure inlet | p = 101.325 kPa, t = 290.15 K | |
top surface | with wind | symmetry | ∂u/∂z = 0, ∂t/∂z = 0 |
without wind | pressure outlet | p = 101.325 kPa, t = 290.15 K | |
ground | wall | ∂u/∂n = 0, ∂t/∂n = 0 | |
heat exchanger | radiator | Δp = f(uf), h = f(uf) |
Parameter | Mesh A and B (%) | Mesh B and C (%) | |
---|---|---|---|
Difference in total mass flow rate | 0 m/s | 2.36 | 0.22 |
4 m/s | 3.07 | 0.29 | |
12 m/s | 4.12 | 0.38 | |
Maximum mass flow rate difference of single fan | 0 m/s | 2.95 | 0.31 |
4 m/s | 3.52 | 0.40 | |
12 m/s | 4.71 | 0.46 |
Wind Direction (°) | Wind Speed (m/s) | Percentage of Rotational Speed (%) | Case 1 | Case 2 | Case 3 | |||
---|---|---|---|---|---|---|---|---|
Mass Flow Rate (kg/s) | Heat Rejection (kW) | Mass Flow Rate (kg/s) | Heat Rejection (kW) | Mass Flow Rate (kg/s) | Heat Rejection (kW) | |||
90 | 3 | 90 | 68,879 | 1,549,763 | 69,068 | 1,547,833 | 67,879 | 1,532,872 |
95 | 69,711 | 1,566,394 | 69,246 | 1,557,416 | 69,612 | 1,561,803 | ||
100 | 70,223 | 1,578,621 | 70,223 | 1,578,621 | 70,223 | 1,578,621 | ||
105 | 70,288 | 1,584,041 | 70,672 | 1,588,579 | 70,828 | 1,590,086 | ||
110 | 71,055 | 1,597,264 | 70,582 | 1,585,677 | 71,051 | 1,595,535 | ||
6 | 90 | 61,487 | 1,417,979 | 61,491 | 1,409,946 | 60,398 | 1,394,444 | |
95 | 62,401 | 1,438,168 | 61,903 | 1,429,842 | 62,048 | 1,430,510 | ||
100 | 62,941 | 1,456,545 | 62,941 | 1,456,545 | 62,941 | 1,456,545 | ||
105 | 63,204 | 1,469,182 | 63,660 | 1,476,573 | 63,836 | 1,479,511 | ||
110 | 64,065 | 1,487,630 | 63,877 | 1,485,461 | 64,473 | 1,495,690 | ||
9 | 90 | 57,332 | 1,334,881 | 57,064 | 1,319,639 | 56,098 | 1,304,733 | |
95 | 57,553 | 1,337,247 | 57,437 | 1,337,495 | 57,545 | 1,337,105 | ||
100 | 58,282 | 1,361,404 | 58,282 | 1,361,404 | 58,282 | 1,361,404 | ||
105 | 58,455 | 1,374,118 | 58,834 | 1,380,497 | 59,077 | 1,384,267 | ||
110 | 59,033 | 1,390,949 | 59,076 | 1,393,135 | 59,614 | 1,401,737 | ||
12 | 90 | 55,345 | 1,293,718 | 55,133 | 1,276,424 | 54,276 | 1,262,936 | |
95 | 55,539 | 1,292,422 | 55,440 | 1,293,513 | 55,539 | 1,292,397 | ||
100 | 56,146 | 1,313,930 | 56,146 | 1,313,930 | 56,146 | 1,313,930 | ||
105 | 56,237 | 1,322,292 | 56,607 | 1,329,848 | 56,829 | 1,333,781 | ||
110 | 56,722 | 1,336,313 | 56,827 | 1,343,527 | 57,348 | 1,349,968 | ||
0 | 3 | 90 | 72,721 | 1,621,333 | 71,839 | 1,609,264 | 72,007 | 1,610,250 |
95 | 72,445 | 1,619,217 | 72,493 | 1,618,320 | 71,333 | 1,602,000 | ||
100 | 72,623 | 1,623,033 | 72,623 | 1,623,033 | 72,623 | 1,623,033 | ||
105 | 72,050 | 1,615,187 | 72,527 | 1,623,643 | 73,174 | 1,633,818 | ||
110 | 72,564 | 1,624,674 | 73,141 | 1,634,291 | 72,726 | 1,629,238 | ||
6 | 90 | 65,325 | 1,469,493 | 64,559 | 1,456,552 | 64,563 | 1,454,133 | |
95 | 65,523 | 1,476,696 | 65,499 | 1,474,718 | 64,801 | 1,464,737 | ||
100 | 65,607 | 1,481,841 | 65,607 | 1,481,841 | 65,607 | 1,481,841 | ||
105 | 65,678 | 1,486,122 | 65,707 | 1,488,071 | 66,271 | 1,496,227 | ||
110 | 65,719 | 1,489,618 | 66,327 | 1,500,288 | 66,083 | 1,498,996 | ||
9 | 90 | 59,717 | 1,372,035 | 58,987 | 1,359,010 | 58,935 | 1,355,934 | |
95 | 59,850 | 1,377,865 | 59,757 | 1,374,559 | 59,139 | 1,365,766 | ||
100 | 59,883 | 1,382,105 | 59,883 | 1,382,105 | 59,883 | 1,382,105 | ||
105 | 59,898 | 1,385,840 | 59,912 | 1,387,501 | 60,400 | 1,394,581 | ||
110 | 59,913 | 1,389,540 | 60,407 | 1,398,398 | 60,195 | 1,397,001 | ||
12 | 90 | 54,840 | 1,299,516 | 54,289 | 1,288,354 | 54,304 | 1,287,079 | |
95 | 54,961 | 1,304,162 | 54,943 | 1,302,169 | 54,457 | 1,295,007 | ||
100 | 55,019 | 1,308,029 | 55,019 | 1,308,029 | 55,019 | 1,308,029 | ||
105 | 55,038 | 1,311,296 | 55,051 | 1,312,888 | 55,432 | 1,318,416 | ||
110 | 55,039 | 1,314,213 | 55,461 | 1,322,241 | 55,252 | 1,320,479 | ||
−90 | 3 | 90 | 60,863 | 1,374,528 | 61,100 | 1,360,978 | 60,335 | 1,356,419 |
95 | 61,087 | 1,370,758 | 61,274 | 1,373,643 | 60,938 | 1,366,882 | ||
100 | 61,451 | 1,382,008 | 61,451 | 1,382,008 | 61,451 | 1,382,008 | ||
105 | 61,852 | 1,384,903 | 62,373 | 1,390,173 | 62,231 | 1,389,286 | ||
110 | 62,931 | 1,402,216 | 62,174 | 1,389,393 | 62,038 | 1,387,204 | ||
6 | 90 | 54,593 | 1,265,818 | 54,149 | 1,248,420 | 53,725 | 1,244,682 | |
95 | 54,888 | 1,266,043 | 54,880 | 1,266,096 | 54,181 | 1,256,483 | ||
100 | 55,662 | 1,279,765 | 55,662 | 1,279,765 | 55,662 | 1,279,765 | ||
105 | 55,986 | 1,281,610 | 56,269 | 1,284,576 | 56,278 | 1,284,057 | ||
110 | 56,641 | 1,287,518 | 56,353 | 1,286,188 | 56,313 | 1,284,294 | ||
9 | 90 | 50,326 | 1,165,777 | 48,410 | 1,131,406 | 47,386 | 1,102,634 | |
95 | 49,919 | 1,163,944 | 49,538 | 1,153,851 | 48,689 | 1,131,573 | ||
100 | 50,187 | 1,166,434 | 50,187 | 1,166,434 | 50,187 | 1,166,434 | ||
105 | 50,554 | 1,164,928 | 50,991 | 1,169,293 | 51,023 | 1,175,106 | ||
110 | 51,118 | 1,170,260 | 51,046 | 1,175,176 | 51,103 | 1,176,050 | ||
12 | 90 | 45,017 | 1,065,833 | 45,157 | 1,056,768 | 44,469 | 1,038,037 | |
95 | 45,440 | 1,062,964 | 45,377 | 1,063,689 | 44,739 | 1,053,349 | ||
100 | 45,764 | 1,072,874 | 45,764 | 1,072,874 | 45,764 | 1,072,874 | ||
105 | 46,606 | 1,091,565 | 47,054 | 1,101,590 | 46,886 | 1,097,847 | ||
110 | 46,943 | 1,097,450 | 47,470 | 1,113,100 | 47,742 | 1,116,004 |
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Huang, W.; Chen, L.; Wang, W.; Yang, L.; Du, X. Cooling Performance Optimization of Direct Dry Cooling System Based on Partition Adjustment of Axial Flow Fans. Energies 2020, 13, 3179. https://doi.org/10.3390/en13123179
Huang W, Chen L, Wang W, Yang L, Du X. Cooling Performance Optimization of Direct Dry Cooling System Based on Partition Adjustment of Axial Flow Fans. Energies. 2020; 13(12):3179. https://doi.org/10.3390/en13123179
Chicago/Turabian StyleHuang, Wenhui, Lei Chen, Weijia Wang, Lijun Yang, and Xiaoze Du. 2020. "Cooling Performance Optimization of Direct Dry Cooling System Based on Partition Adjustment of Axial Flow Fans" Energies 13, no. 12: 3179. https://doi.org/10.3390/en13123179