LUBRICANTS
FEATURE SPONSOR
S cooltaying
With the growing trend to further increase capacity in wind energy there is even more reason for ensuring there are efficient methods of cooling gearboxes, generators and inverters inside the nacelle.
FLUID/AIR COOLERS
The gearboxes, power electronics, generators and transformers, apart from air-cooled versions, are all cooled using light oils or water glycols. Fluid/Air coolers are used for re-cooling by dissipating the excess heat to atmosphere via the surrounding air. These fluid/air coolers are usually installed in an exposed position on the nacelle so that the wind is directed through them.
The airflow through the cooler can either be forced by using a fan (active re-cooling) or naturally by the wind (passive re-cooling). HYDAC has extensive experience in supplying both kinds of solutions and sizing, distribution and configuration of the cooler elements on the nacelle are optimised with the aid of computer-aided simulations.
REDUCING INVESTMENT AND OPERATIONAL COSTS
Passive re-cooling has many advantages over active re-cooling in wind turbine applications, for example investment and operational costs can be reduced, as no electrical energy is required to drive any fans. The disadvantages of passive re-cooling are the potential extra space requirements, which can sometimes dominate the design of the wind turbine nacelle.
The company has developed an optimum layout of passive coolers on wind turbine nacelles. with the aid of numerical flow simulation (CFD) the air flow dynamics of the nacelle including flow through the cooler is calculated and optimised until the maximum cooling capacity is achieved in relation to the area.
The simulation for solution validation can be carried out using very accurate, but also complex calculation methods to obtain maximum safety for the design.
COMPUTATIONAL FLUID DYNAMICS (CFD) CFD refers to computer-aided calculation of flow processes. This type of flow simulation is a relatively new area of technology. In addition to difficulties with the mathematical treatment of the equations, there are further problems with flow calculations which relate to the turbulence of a flow.
DIRECT NUMERICAL SIMULATION (DNS) It is indeed possible to calculate simple flows with all their turbulent processes, using DnS. For industry-related problems, however, this approach is far from practicable because the computational requirements are extremely high. This problem was however resolved by the introduction of so-called turbulence models, even if it does rely on a number of simplifications. nowadays the application of these solution processes is considered state-of-the-art.
In the meantime there are a number of software packages which can be used to calculate flow. The advantages of these flow simulations are easy to appreciate: information is given for all points of the flow field and this provides the opportunity of eliminating weak points and recognising potential improvements. By having an accurate knowledge of all parameters of the
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www.windenergynetwork.co.uk
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