Wind turbine cooling technologies - Wind Power Generation and Wind Turbine Design - page 631

Figure 10: Relationship between wind speed and thickness of the heat exhanger
adopting fi n pair cc1 and ch1.
the wind turbine cooling system. In order to perform an exhaustive and objective
optimization of the system, we will utilize tools such as computer-aided design,
dynamic numerical simulation and so forth combining with the heat production
data in the real-time wind turbine operation to launch a thorough and meticulous
research. By doing these, we are able to render theoretical support to the future
design of high-performance, reliable and economic wind turbines.
5 Future prospects on new type cooling system
With the wide application of wind energy at coastline area, the unit capacity of
wind turbines increases greatly [22], which leads to a large rise of the heat produc-
tion in gearboxes, generators and converters. The current liquid cooling system
will no longer be suffi cient to meet the cooling demands of wind turbines. Besides,
the current cooling system has not taken full advantage of the ambient environ-
ment, such as high wind velocity, large solar energy density, etc. Therefore, there
is a great potential to improve the operation economical effi ciency. To solve the
two problems above, some new cooling techniques for wind turbines are proposed
in this section as follows.
5.1 Vapor-cycle cooling methods
From the theories of thermodynamics, all the current wind turbine cooling methods
absorb heat by utilizing the specifi c heat capacity of the medium, while the vapor-cycle
cooling uses the gasifi cation latent heat of the boiling fl uid to deliver the heat. As the
gasifi cation latent heat of the fl uid is much larger than its specifi c heat capacity, the effect
of the vapor-cycle cooling will be more obvious [ 24 ]. Therefore, the implementation of
the vapor-cycle cooling technology is worthy of consideration. As shown in Fig. 11,
its feature is that the system sets a vapor-cycle refrigerating engine outside the nacelle.
During the operation, the cooling medium fl ows through the heat exchangers which
is installed outside the gearbox, the generator, and the control converter successively,