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EOLIOS carried out a thermo-aerodynamic audit of the Höganäs Belgium site.
Ath - Belgium
EOLIOS carried out a thermo-aerodynamic audit on the site of Höganäs Belgium, a company specializing in high-alloy powder metallurgy. The main aim of this study was to lower temperatures and improve heat dissipation, with particular emphasis on the melting hall, where the two furnaces are located. This initiative was designed to increase operator comfort throughout the production process. The central challenge of the project was to master the specific thermo-aerodynamic phenomena associated with the various manufacturing stages at extremely high temperatures.
This audit studies ventilation and openings to identify the first possible improvements.
Two large doors at either end of the building are usually left open on the first floor, letting the air in. Another door, leading to the storage hall, is often open, allowing air to escape from the study area. All plant doors function as air inlets, causing significant fresh air infiltration when open, which can lead to discomfort in winter.
Air inlets are also present on the upper floor of the building, and to improve the comfort of technicians working close to the furnaces, several fans have been installed on the second floor.
Furnaces generate a lot of heat, which rises to the roof. To lower the temperature on the upper floor of the building, ventilators are placed on the roof, facilitating the evacuation of heat to the outside.
The roof is equipped with various natural air extraction devices.
Smoke tests reveal various air circulation patterns in the building. Upstairs, the air flows out through the open windows, while some rises to the roof. In the vicinity of the fans, the warm air is drawn downwards, creating a homogenized temperature, albeit with an increase in heat in the lower areas. Fans in the vicinity of ovens generate air movement, but are not conducive to better heat dissipation. In some areas, biflow occurs, with warm air rising to the extraction loops and cooler air flowing to the furnaces. Thermal stratification phenomena also occur, separating zones of warm and cold air.
The aim of this section is to highlight the main sources of thermal phenomena and the areas that are more or less dense with heat. Thermal camera analyses are used to map hot and cold zones in support of numerical studies.
Computational Fluid Dynamics (CFD) is a numerical approach to analyzing fluid flows in a given environment, particularly in building design. It provides information on air velocities, pressures and temperatures in and around building spaces. This method uses partial differential equations to numerically solve the phenomena, taking into account boundary conditions such as building aeraulics, internal heat gains and air-conditioning systems. CFD simulations are essential for optimizing ventilation and air conditioning in large spaces, guaranteeing optimum comfort.
Partial differential equations require boundary conditions to be solved. These are established on the basis of on-site measurement data and information from the project manager. For a steady-state study in a space open to the outside, we need to define the characteristics of the walls (material, physical properties, viscosity, temperature) as well as those of the surfaces exposed to the outside (flow direction, velocity, pressure, temperature, surface coefficients). It’s crucial to guarantee computational stability when defining these conditions, as the equations are solved iteratively to get closer to the solution.
The code solver used approximates the equations at each mesh node, respecting the fundamental principles of physics (conservation of mass and energy). It uses the standard k-epsilon turbulence model, which solves for two variables: turbulent kinetic energy and the kinetic energy dissipation rate. This model is widely used in industrial and HVAC applications because of its good convergence speed and acceptable memory requirements. For thermoaerulic studies, the effect of radiative exchanges between walls, thermal conduction, thermal draught and gravity are taken into account. The studies are carried out on the whole building, without establishing a symmetry section.
As part of the CFD study, the entire building was modeled to take into account the different aeraulic masks created by the site’s various modules.
The furnaces and internal configuration of the melting building were modeled from site data, as were the fans and openings affecting air movement. The aim is to obtain an accurate representation of the complex air movements specific to these premises.
The studies were carried out to analyze the thermal phenomena present on the site. Two distinct scenarios were used: a baseline scenario similar to the audit conditions, and a calorie extraction optimization scenario. The site audit revealed that there is no thermal rise on the first floor, unlike on the second floor where the heat released by the furnaces warms the ambient air and the roof. Roof temperatures of up to 50°C are not caused by solar radiation, but by the furnaces and preheating of the molds. There’s also a lack of air extraction under the roof, so heat-laden air remains trapped. A study was carried out to determine the thickness of the insulation. The first scenario, similar to the audit, confirmed the observations made during the audit, particularly with regard to temperature distribution.
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