Wind Turbine Services: We help you solve problems related to wind turbine cooling systems
22.02.2016
By Kalle Jalonen, Project engineer, KL-Lämpö Oy
The type of coolant used in cooling systems is not the first thing on our mind when building a new wind turbine. Even if the wind turbine has been in operation for a while, there are other maintenance projects that take priority. However, attention should be paid to the type and condition of coolants in order to avoid unnecessary repair costs.
Special conditions, coolants under high stress
Coolants which are used in the cooling systems of ordinary buildings normally age within up to ten years before the need of replacement. This is an excellent point of comparison with the coolants used in wind turbines. In ordinary buildings the circulation speed of coolants varies between 1 – 2 m/s while in wind turbines it is much higher. When the coolant circulates at such a high speed it tends to form bubbles. This leads to reduction in cooling capacity and may also cause corrosion. Cooling systems are exposed to high mechanical stress.
Propylene glycol (MPG) solutions with a very high glycol content (up to 50 %) are used in the cooling systems of wind turbines under the cold northern weather conditions. However, ethylene glycol (MEG) solutions with a 30 – 40 % glycol content are commonly used in buildings because of their better frost resistance. MPG solutions have a weaker heat transfer capacity compared to MEG solutions. However, MPG solutions are used because of their eco-friendliness.
Under the circumstances it may be too optimistic to expect the coolants used in wind turbines to last for 3 – 5 years.
Anticipating and solving problems
Coolants should be pumped into cooling systems in the construction phase of wind turbines. Normally the lifetime of a wind turbine ranges from 20 to 25 years. Anyhow, coolants used in cooling systems can deteriorate only within a few years and lose their heat transfer capacity. Impurities are precipitated in glycol solutions. This may lead to formation of scale and deposits on the heat transfer surfaces of cooling systems. As a result there may be clogs in the cooling modules of inverters.
Deposits clogging the system
Insufficient cooling capacity may lead to the overheating of a wind turbine and unforeseen production stoppages. An extra service visit is often required and maintenance costs rise.
In the worst case expensive components, like inverters, may be damaged. There are at least 10 inverters or even more in wind turbines. Replacing them is a very laborious task and can cost tens of thousands euros.
Radiators may also cause problems in cooling systems if coolants and their condition are neglected. If a radiator starts to leak because of corrosion, it has to be replaced. Radiators and their spare parts are expensive and their replacement is a laborious task.
Often expensive spare parts have to be kept in stock which leads to extra costs. It is possible to minimize the risks of damages to expensive components as well as production stoppages by preventive maintenance.
The above mentioned problems can be anticipated and solved in time. Our cost-efficient solutions for wind turbines have been tested and they are effective even in most rigorous conditions.
For further questions, please contact our experts ›