Cooling towers – ICPE
Thermo-aerodynamic analysis of a data center roof
The study focuses on cooling towers located on the roof of a data center. These cooling systems are essential for data centers. That’s why we need them to work optimally. During this study, the principle of system looping was studied and solutions recommended to remedy it.
Studies of cooling towers as part of an ICPE project
Year
2024
Customer
SETEC
Location
France
Typology
Air & Wind
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Study of cooling towers in an ICPE data center
The challenge of cooling data centers
The study carried out by EOLIOS concerns the sizing and implementation of cooling tower systems on the roof of an ICPE (Installations Classées Protection de l’Environnement) data center.
Cooling data centers is of paramount importance. These data centers house a multitude of servers and IT equipment that generate a considerable amount of heat. If this heat is not properly dissipated, it can cause failures and breakdowns, compromising system availability and service continuity. Overheating can shorten equipment life, increase energy consumption and generate additional maintenance costs. It is therefore essential to install efficient cooling systems to maintain a stable and appropriate temperature inside data centers. This guarantees optimum performance, greater reliability and controlled energy consumption.
Cooling towers: Operating principle
Cooling data centers is of paramount importance. These data centers house a multitude of servers and IT equipment that generate a considerable amount of heat. If this heat is not properly dissipated, it can cause failures and breakdowns, compromising system availability and service continuity. Overheating can shorten equipment life, increase energy consumption and generate additional maintenance costs. It is therefore essential to install efficient cooling systems to maintain a stable and appropriate temperature inside data centers. This guarantees optimum performance, greater reliability and controlled energy consumption.
Numerical simulation of conditions around TARs
Modeling the ICPE building
The study was carried out using CFD simulation. This method can be used to model and analyze fluid flows into and out of TARs. As part of this study, a 3D model of the building concerned was developed. This model provides a detailed representation of the building’s structure and its surroundings within a 400-meter radius. It is based on a sectional drawing of the project and a 3D model supplied. By taking into account the surrounding buildings, we can provide a more accurate picture of the wind’s evolution on site. As the site is densely populated with infrastructure, these constitute a large number of aeraulic masks, greatly influencing the evolution of the air. The study building has been accurately modeled. The ARTs on the roof were modelled according to the data sheets supplied by the customer. There are 6 TARs on the roof.
CFD simulation: an accurate tool for analyzing TAR environmental conditions
CFD simulation provides precise, detailed results, taking into account many factors such as building geometry, environmental conditions and the properties of the materials used. Thanks to CFD simulation,EOLIOS engineers can provide technical solutions and recommendations adapted to this project. This enables customers to make informed decisions and optimize the sizing and installation of RATs on the building’s roof.
3D model of TARs
Results of the thermo-aerodynamic study
Influence of wind on the building
Wind is an extremely changeable phenomenon, both in terms of direction and speed. While maximum wind speed values are essential for structural stability calculations, average wind speed and direction values are more appropriate for thermo-aerodynamic studies. In our study, the wind is considered to be constant with a direction perpendicular to the site.
Initial results show that the wind has a strong influence on the air currents around the building, creating three zones of disturbance: at the front of the building, at the rear and further out in the wake of the building. TAR discharges are directed upwards and follow the wind. An upstream wall limits air flow to the TARs, creating low-velocity zones upstream and downstream.
TAR looping: A challenge for optimal cooling
The temperature results show variations at the air inlets of the TARs. A clear distinction can be made between the loop affecting these devices, particularly with two central TARs (A) and two on the right (B and C) which capture air at a higher temperature than that of the environment, which is also the case for the TAR on sides (D and E).
TARs in position A encounter a zone where the temperature is higher, due to a reduction in the supply of fresh air caused by the proximity of suction points. Between the TARs in positions B and E, a similar phenomenon is observed at a slightly lower temperature, thanks to the greater distance between these units. In particular, TARs in position B and especially C, due to their proximity to the walls of the rooms where the air intakes are located, capture air at a significantly higher temperature than the ambient air. These TARs are confined between two walls, which reduces fresh air intake. This analysis underlines the importance of optimizing the design of air inlets to ensure an adequate supply of fresh air and avoid overheating problems.
The drawing shows the humidity conditions at the TAR air inlets. Note the looping phenomenon, where several TARs (A, B, C, D and E) draw in air with high humidity levels. The central TAR (A) and those on the right (B and C) attract particularly humid air, while those on the sides (D and E) also capture humid air, albeit to a lesser extent. This looping pattern for humidity corresponds to that observed for temperatures, and is due to similar factors. Higher humidity levels are also observed between TARs in A, as well as between those in B and E.
Simulation shows that ARTs expel humid air, which is then sucked back in, creating a looping phenomenon. This problem is exacerbated when the air inlets of one TAR face another TAR or an obstacle such as a wall. This prevents access to fresh air at room temperature and moderate humidity. As a result, TARs tend to draw in air from higher up, which is warmer and more humid.
Theextent of looping and theeffect of obstacles on moisture evacuation are detrimental to system efficiency. The current layout of ventilation systems on the roof seems inadequate. These observations highlight the need for design review and modifications to improve TAR performance and ensure optimum efficiency.
Improving TAR efficiency: EOLIOS recommendations to limit looping
Based on these observations, EOLIOS is proposing various solutions to reduce TAR looping.
One of the key proposals, based on the results of the study, would be toinstall ventelles in place of the wall around the TARs. This measure is designed to mitigate the aeraulic masking effect created by the wall, which limits the intake of fresh air and creates areas of low air velocity in the lower part of the TAR. The louvers will improve airflow, bringing in fresh air more efficiently and reducing air stagnation problems.
Should the installation of vents prove insufficient, and the systems continue to loop back on themselves, we recommend the installation of horizontal hoods at the level of the systems’ discharges, to limit the downward flow of plumes towards the intake.
If it proves too complicated to install a full horizontal hood, one option is toinstall several horizontal hoods at the TAR intake.
The installation of vertical hoods at TAR outlets would also make it possible to increase the distance between the discharge and the TAR intake, and thus limit looping effects. This solution will still be less effective than a horizontal cowling.
This study demonstrates theimportance of using CFD simulation to understand and optimize TAR performance. Thanks to this method, we were able to analyze in detail the air flows, temperatures and humidity around the TARs, revealing areas of disturbance and phenomena such as airflow looping. CFD simulation offers advantages such as accurate results, cost and time savings, and a better understanding of the factors that influence TAR operation. Using this knowledge, recommendations such as the installation of louvers in place of walls have been formulated to promote a better supply of fresh air and improve TAR performance.
Reduce the spread of legionella with CFD
Studying the spread of legionellosis in evaporative cooling plants such as ARTs is essential to prevent the transmission of this potentially fatal respiratory disease. Legionella bacteria, responsible for Legionnaires’ disease, thrive in warm water environments such as water treatment plants.
When bacteria-contaminated water is sprayed into the air by TAR fans, it creates a moist plume that may contain infected droplets. When these droplets are inhaled by people in the vicinity of TARs, they can cause respiratory infections, including legionellosis.
CFD studies play a crucial role in understanding and managing the spread of legionellosis. CFD studies can be used to visualize airflow and the dispersion of wet plumes generated by TARs. Thanks to the results of CFD simulations, it is possible to identify areas at risk and take measures to prevent the spread of Legionella. These measures can include adapting ART design, modifying fan operation, adjusting water spray parameters, or implementing more efficient water monitoring and treatment systems. CFD studies thus help to improve the safety and reliability of evaporative cooling plants, by minimizing the risk of legionella spreading. They enable us to assess the effectiveness of preventive measures put in place, and to optimize the design and operation of ARTs in order to reduce risks to public health.
Video summary of the study
Summary of the study
The study focused on the optimum placement of vents to improve thermal comfort at the Aluminium Dunkerque plant, which uses a natural ventilation cooling system. The aim is to determine whether the current aeration system is sufficient for the addition of an 8th furnace and, if so, to propose solutions.
Various preliminary measurements were carried out, such as smoke tests to observe air movements, temperature measurements and thermal images to identify heat sources. These data were used to create a 3D model of the plant in which numerical CFD simulations were carried out.
CFD simulations are used to study fluid flows and simulate the plant ‘s aeraulic and thermal conditions. The results showed that the addition of certain aerators would enable faster, more targeted evacuation of hot air, thus improving the site’s aeraulic operation.
In conclusion, this study enabled us to determine the optimum placement of vents to improve thermal comfort at the Aluminium Dunkerque plant, with a view to adding an 8th furnace. The results of the CFD simulations provided precise recommendations for optimizing energy efficiency and the well-being of plant operators.
