When planning its new Westeinde wind farm in Anna Paulowna (NL), wind turbine manufacturer EWT realised it needed a solution for additional heat losses in their ever more powerful wind turbines. Needless to say, they soon turned to Renson. One condition was that resistance to burglaries could not be compromised in any way by fitting ventilation louvres to the turbines.
“The reason for our partnership with Renson was an increase in the rated power of our wind turbines from 900 kW to 1 MW. In addition, the net transformer, which is usually located in an external building, was placed inside our turbines. This caused our heat losses to double, and we had to compensate for this in an efficient manner,” EWT’s Mechanical Engineering Manager Danny Ferket explains. “We previously had a cooling system in our wind turbines, but this was no longer able to cope with the new configuration. There were various options to compensate for this, from increasing the airflow to reducing the pressure drop inside the turbine – or installing a different type of cooling altogether. We eventually chose to fit ventilation louvres to create an additional inflow of cooler (outside) air. This solution offered the best balance between cost and durability.”
On the flip side, ventilation louvres could potentially lower the burglar resistance of the doors in the wind turbines. Considering the fact these turbines contain lots of metals that are attractive to thieves, this posed a real problem. “That’s why we were specifically looking for louvres that complied with burglar-resistance class RC3 as a minimum; the same class as our doors, which are made of 8 to 12 mm of lasered stainless steel,” Danny Ferket continues. “The dimensions of the ventilation louvres were eventually decided by the airspeed and the amount of space they were allowed to take up in the wind turbine doors.”
Engineers from both Renson and EWT put their heads together to find the perfect louvres of this application. “As part of this, Renson showed the necessary flexibility to develop louvres that met our specific (burglar resistance) requirements. Our partnership with Renson could not have gone better, and after validation in our test turbines using CFD analyses, we gave them the green light to install the louvres at our Westeinde wind farm in Anna Paulowna,” Danny Ferket concludes.
Hans Bannink (Renson): “The ventilation louvres in question were fitted with an additional removable frame with a dust filter and special mountings for easy installation in the doors of the wind turbines. The main reason for these filters was to protect the advanced equipment inside the turbine against unwelcome visitors and outside influences such as torrential rain or storms. The fact that they are easy to replace helps limit the pressure drop. Eventually, two types of louvres were developed to maximise the flow of fresh outside air for each door in order to provide the necessary cooling.”
Danny Ferket: “These ventilation louvres offer us extra flexibility in hotter areas, as well as the option to install an internal transformer. This has enabled us to expand our product portfolio in response to demand from the market and specific environmental requirements. The straightforward installation process also gives us the flexibility to add the louvres at the last minute,” Danny Ferket concludes.