scholarly journals Cooling Performance Optimization of Direct Dry Cooling System Based on Partition Adjustment of Axial Flow Fans

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3179
Author(s):  
Wenhui Huang ◽  
Lei Chen ◽  
Weijia Wang ◽  
Lijun Yang ◽  
Xiaoze Du
Keyword(s):  
Wind Direction ◽  
Performance Optimization ◽  
Cooling System ◽  
Axial Flow ◽  
High Wind ◽  
Power Generating Unit ◽  
Wind Speeds ◽  
Mass Flow Rates ◽  
Computational Fluid Dynamics Cfd ◽  
Dry Cooling

Axial flow fans play key roles in the thermo-flow performance of direct dry cooling system under windy conditions, so the energy efficiency of a power generating unit can be improved by optimizing the operation strategies of the axial flow fans. In this work, various measures based on the partition adjustment of axial flow fans with constant power consumption of a 2 × 660 MW power plant are studied by computational fluid dynamics (CFD) methods. The results show that increasing the rotational speed of the windward fans is beneficial to reduce the inlet air temperature and increase the mass flow rates of the fans, which enhance the heat rejections of the air-cooled condensers, especially at high wind speeds. Moreover, the turbine back pressures for the optimal and original cases are achieved by iterative methods, with the largest drop of 2.77 kPa at the wind speed of 12 m/s for 110-case 3 in the wind direction of −90°. It is recommended to adopt 110-case 1 and 110-case 3 at low and high wind speeds, respectively, in the wind directions of 90° and −90°, while 110-case 2 is always the best choice in the 0° wind direction.

Impact of tower spacing on the performance of multiple short natural draft dry cooling towers for calm conditions

2020 ◽  
pp. 095765092096224
Author(s):  
Mehrdad Khamooshi ◽  
Timothy N Anderson ◽  
Roy J Nates
Keyword(s):  
Cooling System ◽  
Cooling Towers ◽  
Cfd Simulations ◽  
Heat Rejection ◽  
Natural Draft ◽  
Air Supply ◽  
Close Proximity ◽  
New Finding ◽  
Computational Fluid Dynamics Cfd ◽  
Dry Cooling

Natural draft dry cooling towers (NDDCTs) serve a fundamental role in the deployment of concentrating solar power (CSP) plants. In a multi-tower cooling system, there is a need to be able to position them correctly so that their performance as a group is maximised. To do this, an understanding of the effect they have on one another is needed. Hence, this work investigated the effect of tower spacing on the performance of multiple cooling towers under calm conditions using computational fluid dynamics (CFD) simulations. The applied CFD methods were validated by comparing the current results with real cooling tower results. It found that towers in close proximity would compete for air at their inlet, resulting in distorted velocity and temperature distributions at the radiator surface. Furthermore, the results show that at a tower spacing of less than two tower diameters (2 D) where D is the diameter of the tower, a reduction in the scavenging area between the towers limits the air supply to the towers and this interaction decreases the cooling performance of the towers. The results of three NDDCTs showed that the heat rejection of the middle tower which is surrounded by two towers is highly influenced by the tower spacing and at very low tower spacings, the heat rejection decreases by up to 15%. This new finding holds particular design significance if multiple NDDCTs are deployed on CSP sites that experience a high frequency of calm (no-wind) conditions.

scholarly journals Investigation of Thermo-Flow Characteristics of Natural Draft Dry Cooling Systems Designed with Only One Tower in 2 × 660 MW Power Plants

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1308
Author(s):  
Mohan Liu ◽  
Lei Chen ◽  
Kaijun Jiang ◽  
Xiaohui Zhou ◽  
Zongyang Zhang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Power Plants ◽  
Cooling System ◽  
Flow Characteristics ◽  
Cooling Systems ◽  
Natural Draft ◽  
Wind Speeds ◽  
Flow And Heat Transfer ◽  
Power Load ◽  
Dry Cooling

In recent years, natural draft dry cooling systems with only one tower have been adopted in some 2 × 660 MW power-generating units owing to the advantage of lower construction costs. The operating cases of two power-generating units and one power-generating unit will both appear based on the power load requirement, which may lead to very different flow and heat transfer performances of this typical cooling system. Therefore, this research explores the local thermo-flow characteristics of air-cooled heat exchangers and sectors, and then analyzes the overall cooling performance of the above two operating cases under various wind conditions. Using the numerical modeling method, the results indicate that the flow and heat transfer performance of this cooling system decreases significantly in the case of one unit with half sectors dismissed. At wind speeds lower than 8 m/s, the difference in turbine back pressure between two units and one unit appears obviously higher than in other wind conditions, even reaching 4.37 kPa. Furthermore, the air-cooled heat exchanger in the lower layer always has better cooling capability than that in the upper layer, especially in conditions where there is an absence of wind and under low wind speeds. The operating case of one unit is not recommended for this dry cooling system because of the highly decreased energy efficiency. In conclusion, this research could provide theoretical support for the engineering operation of this typical natural draft dry cooling system in 2 × 660 MW power plants.

scholarly journals Energy-Saving Strategies of Axial Flow Fans for Direct Dry Cooling System

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3176
Author(s):  
Wenhui Huang ◽  
Lei Chen ◽  
Lijun Yang ◽  
Xiaoze Du
Keyword(s):  
Flow Field ◽  
Energy Saving ◽  
Cooling System ◽  
Axial Flow ◽  
Operating Conditions ◽  
Total Power ◽  
Cooling Power ◽  
Prevailing Wind Direction ◽  
Cooling Air ◽  
Dry Cooling

The operating conditions of axial flow fans are closely related to the thermo-flow characteristics of the mechanical draft direct dry cooling system. Moreover, the uneven distribution of cooling air driven by axial flow fans may lead to the deterioration of the heat transfer capacity of air-cooled condensers (ACCs). Therefore, developing energy-saving operating methods for axial flow fans is very meaningful. In this work, two kinds of adjustment strategies to make the flow field more uniform are proposed for a 2 × 300 MW direct dry cooling power-generating unit. The performance of ACCs in the prevailing wind direction is predicted with the help of the macro heat exchanger model. It is found that the inlet air temperatures of fans are significantly reduced by proposed strategies, especially at high wind speeds. Moreover, the minimum cooling air can meet the cooling demand of ACCs for the strategy which made the air flow rates of all fans consistent. Compared with the case without adjustment of fans, the total power consumption of the fan array was cut down effectively, up to 13.94% at the wind speed of 12 m/s. In conclusion, the energy efficiency of ACCs can be improved by the uniform flow field.

Numerical Investigation of the Performance of a Forced Draft Air-Cooled Heat Exchanger

2017 ◽  
Author(s):  
Ruan A. Engelbrecht ◽  
Johan Van der Spuy ◽  
Chris J. Meyer ◽  
Albert Zapke
Keyword(s):  
Heat Exchanger ◽  
Axial Flow ◽  
Disk Model ◽  
Validation And Verification ◽  
Wind Speeds ◽  
Power Stations ◽  
Modelling Techniques ◽  
Computational Fluid Dynamics Cfd ◽  
Forced Draft ◽  
Air Cooled Heat Exchanger

This paper details the design, validation and verification of two implicit modelling techniques used to model an Air-Cooled Condenser (ACC) in the computational fluid dynamics (CFD) code environment of OpenFOAM (Open Source Field And Manipulation). The actuator disk model was chosen as the axial flow fan model and the heat exchanger model was implemented as an A-frame, or Delta frame, heat exchanger commonly found on power stations. Both models were validated and verified. A 30 fan ACC was verified against previous literature. The results for all validation and verification procedures showed good agreement with respective data. Three different fan configurations in an ACC were compared at different wind speeds namely the A-fan, B2a-fan and a Combined ACC. The study showed small differences between ACCs with regard to fan and thermal performance. However, the B2a-fan ACC consumed 20% less power than the A-fan ACC and 3–10% less power than the Combined ACC. This performance increase was most prominently show-cased by the increased heat-to-power ratio with the B2a-fan exhibiting heat-to-power ratios of 110 W/W compared to 96 W/W for the A-fan.

Numerical Investigation and Performance Optimization of an Air-Cooled Steam Condenser Cell Under Ambient Conditions

2011 ◽  
Author(s):  
Weifeng He ◽  
Yiping Dai ◽  
Qingzhong Ma
Keyword(s):  
Flow Field ◽  
Performance Optimization ◽  
Ambient Air ◽  
Absolute Pressure ◽  
High Wind ◽  
Ambient Conditions ◽  
Wind Speeds ◽  
Hot Air ◽  
Porous Media Model ◽  
And Performance

Air-cooled steam condensers (ACSCs) are so sensitive to the unpredictable ambient conditions that it is quite necessary to find the mechanism how the ambient conditions get into reaction and reasonable measurements can be employed to improve the performance. The numerical model of an ACSC cell is established in the paper. The influence of the ambient conditions on the performance of the ACSC cell is investigated, and the final stable back pressure (absolute pressure) the ACSC cell operates at is forecasted. Finally, wind wall is equipped to change the flow field around the ACSC cell and the performance is optimized. Aerodynamic characteristic of the ACSC cell is simulated by employing the FAN boundary and porous media model in FLUENT. User Define Function (UDF) based on the actual steam property is loaded to simulate the condensation of the steam in the exchangers. The flow field around the ACSC cell varies with the different wind speeds and directions. As a result, the fan volumetric effectiveness and the exchanger performance both decrease under high wind speed and adverse wind direction. Wind temperature gets into reaction mainly because it changes the cold side temperature of the exchangers. Under high wind temperature, the reduced temperature difference decreases the heat transfer rate between the exhaust steam and the ambient air. The equipped wind wall successfully reduces the hot air recirculation (HAR) although the fan performance is also affected due to the gathering effect between the wind wall and heat exchangers, and the performance of the ACSC cell is significantly improved under the dual effects.

scholarly journals Tower Configuration Impacts on the Thermal and Flow Performance of Steel-Truss Natural Draft Dry Cooling System

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 2002
Author(s):  
Huiqian Guo ◽  
Yue Yang ◽  
Tongrui Cheng ◽  
Hanyu Zhou ◽  
Weijia Wang ◽  
...  
Keyword(s):  
Cooling System ◽  
Engineering Application ◽  
Flow Characteristics ◽  
Cooling Systems ◽  
Cylindrical Configuration ◽  
Natural Draft ◽  
Steel Truss ◽  
Draft Force ◽  
Mass Flow Rates ◽  
Dry Cooling

In recent years, the steel-truss natural draft dry cooling technique has received attention owing to its advantages in better aseismic capability, shorter construction period, and preferable recycling. For cooling towers generating the draft force of air flow, its configuration may impact the thermal and flow performance of the steel-truss natural draft dry cooling system. With regard to the issue, this work explored the thermal and flow characteristics for the steel-truss natural draft dry cooling systems with four typical engineering tower configurations. By numerical simulation, the pressure, flow, and temperature contours were analyzed, then air mass flow rates and heat rejections were calculated and compared for the local air-cooled sectors and overall steel-truss natural draft dry cooling systems with those four tower configurations. The results present that tower 2 with the conical/cylindrical configuration had slightly lower heat rejection compared with tower 1 with the traditional hyperbolic configuration. Tower 3 with the hyperbolic/cylindrical configuration showed better thermo-flow performances than tower 1 at high crosswinds, while tower 4 with the completely cylindrical configuration appeared to have much reduced cooling capability under various crosswind conditions, along with strongly deteriorated thermal and flow behaviors. As for engineering application of the steel-truss natural draft dry cooling system, the traditional hyperbolic tower configuration is recommended for local regions with gentle wind, while for those areas with gale wind yearly, the hyperbolic/cylindrical integrated cooling tower is preferred.

scholarly journals Dependence of Power Characteristics on Savonius Rotor Segmentation

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2912
Author(s):  
Krzysztof Doerffer ◽  
Janusz Telega ◽  
Piotr Doerffer ◽  
Paulina Hercel ◽  
Andrzej Tomporowski
Keyword(s):  
High Wind ◽  
Horizontal Axis Wind Turbine ◽  
Savonius Rotor ◽  
Power Characteristics ◽  
Wind Speeds ◽  
Single Segment ◽  
High Elongation ◽  
Low Wind Speeds ◽  
Number Of Segments ◽  
Rotor Type

Savonius rotors are large and heavy because they use drag force for propulsion. This leads to a larger investment in comparison to horizontal axis wind turbine (HAWT) rotors using lift forces. A simple construction of the Savonius rotor is preferred to reduce the production effort. Therefore, it is proposed here to use single-segment rotors of high elongation. Nevertheless, this rotor type must be compared with a multi-segment rotor to prove that the simplification does not deteriorate the effectiveness. The number of segments affects the aerodynamic performance of the rotor, however, the results shown in the literature are inconsistent. The paper presents a new observation that the relation between the effectiveness of single- and multi-segment rotors depends on the wind velocity. A single-segment rotor becomes significantly more effective than a four-segment rotor at low wind speeds. At high wind speeds, the effectiveness of both rotors becomes similar.

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