WO2008102184A2

WO2008102184A2 - Cooling apparatus for a wind turbine

Info

Publication number: WO2008102184A2
Application number: PCT/GR2008/000013
Authority: WO
Inventors: Dionysios Choidas
Original assignee: Dionysios Choidas
Priority date: 2007-02-22
Filing date: 2008-02-22
Publication date: 2008-08-28
Also published as: GR1006291B; GR20070100109A; WO2008102184A3

Abstract

A system for the handling of the heat loads produced by a wind turbine. The present invention proposes a novel method (and various arrangements for its materialization) based on the transfer of the heat loads from the nacelle to a 'meeting point' where these heat loads are being transferred -through a device called, as 'thermal carrier' (100) to a cooling liquid which circulates between the aforementioned 'meeting point' and a still heat exchanger located remotely from the nacelle. One principal aspect of this invention is that the cooling liquid arrives at the 'meeting point' (and leaves the 'meeting point') under ambient atmospheric pressure. A pump (2) draws coolant form a heat exchanger (1) and transfers this coolant to a still nozzle (3) located near the thermal carrier (100) which is rotating simultaneously with the nacelle, around a vertical axis, during the continuous re-orientation of the wind turbine to the direction of the wind. The nozzle (3) injects a spray of coolant which covers a distance before its landing on the surface of the thermal carrier. Therefore, under ambient pressure, the coolant removes heat load from the thermal carrier and fells, due to the gravity, inside a heat bowl (12) from where it is re-introduced inside a heat exchanger which is located, usually, in a still position and, preferably, outside of the pylon.

Description

COOLING APPARATUS FOR A WIND TURBINE

The invention refers to a system for the handling of the heat loads produced by a wind turbine. These thermal loads, according to their source, are produced by parasitic losses in the gearbox of the turbine or the electric part of the generator (power control systems etc.) It is known that the horizontal axis wind turbine generator consists from a nacelle (which contains the electromechanical part of the wind turbine incorporating the rotor with the wind blades) and a mast or pylon of considerable height on top of which the nacelle is been attached (figure 11) One principal characteristic of this arrangement is the ability of the nacelle (1001) to rotate in accordance to me still pylon (1002) in such a way as to perform a continuous re-orientation of the turbine rotor according to the direction of the wind.

In any case where the parasitic thermal loads, which are being produced by the wind turbine/generator, are greater than a level, there is a need for the provision of an appropriate system which is capable to transfer these thermal loads outside of the turbine in order to protect selected devices from overheating. Usually, this is being performed by a heat exchanger - a device inside of which a fluid circulates which fluid carries the heat loads. Preferably, this fluid is the lubricant of the gearbox of the turbine or another, appropriate fluid which carries the heat loads, either from the gearbox or (if the heat is of ohmic origin) from the electric power control systems of the nacelle. In most cases, the "electric origin" heat loads are being transferred to the surrounding air through heat dissipating surfaces (metallic fins) which are exposed to an air stream without the need of an additional, intermediate cooling liquid. Conventionally, it is preferred mat these aforementioned heat dissipating fins and, also, the aforementioned heat exchanger (air/liquid, in this case) are attached to a selected place of the rotating nacelle - and therefore, they are moving with the nacelle during its continuous re-orientation according to the direction of the wind.

During the last years, the constantly increasing nominal power of the wind turbines has started to expose the actual limitations which exist in the problem of the management of the parasitic heat loads using the conventional methods provided by the known technical level. The traditional heat dissipating systems which are being attached to the nacelle solve the problem up to a certain degree but, also, create some new problems of their own. Sometimes, these problems are of structural origin, relating to the disproportional volume increase of the heat exchangers. Sometimes there are thermal problems (i.e. inefficient handling of peak heat loads) whenever the wind power exceeds a limit.

The "static heat exchanger" concept for the dissipation of the heat loads of the nacelle is being increasingly accepted, during the recent years. According to this proposition of the technical level, the final dissipation of the heat loads to the surrounding environment is being performed by a heat exchanger which is attached to a still place, away from the nacelle (located on the pylon, for example). In this case, the heat exchanger is connected to the nacelle through an appropriate arrangement for the transfer of heat loads from the nacelle to the exchanger (Usually, this arrangement consists of pipes containing circulating fluid).

Up to this moment, there are some propositions from the technical level which utilise the pylon (and, specifically, its exposed surface) as an air/liquid heat exchanger. Also, there are some proposals teaching the feasibility of the transmission of this heat energy to certain remotely located receivers where this heat energy is being utilized productively (for the desalination of sea water, for example) before its final "dumping" to the environment. In all these aforementioned proposals, numeral different solutions are being adopted for the transfer of the thermal loads from the moving part (nacelle) to the still part (pylon) of the wind turbine - the problem is mat every one of these solutions is not absolutely satisfactory.

A notable solution for the utilization of a static heat exchanger is described in the document US6520737. In this case, the cooling medium is sea water (and if there is an external heat exchanger, it can be located under the sea surface) and the transmission of the heat loads from the moving nacelle to the outer heat exchanger (the sea, itself) is being performed through an innovatively sealed fluid connector, characterized by its high cost and, also, a questionable long term reliability due to the elevated pressure of the liquids which circulate inside the fluid connector. There are also many other similar solutions with their long term reliability being a common questionable point.

The present invention proposes a low cost solution for the "heat path connection" between the nacelle and the heat exchanger. And the principal characteristic of this solution is the elimination of any need for a liquid-sealed connector (i.e. of the kind of the proposed connector in document US6520737) between the nacelle and a static (still) exchanger.

The present invention proposes a novel method (and various arrangements for its materialization) based on the transfer (directly or indirectly, through a first cooling liquid) of the heat loads from the nacelle to a "meeting point" where these heat loads are being transferred (through a device called, hereinafter, as "thermal carrier") to another cooling liquid which circulates between the aforementioned "meeting point" and a still heat exchanger located remotely from the nacelle. One principal aspect of this invention is that this aforementioned second cooling liquid arrives at the "meeting point" (and leaves the "meeting point") under ambient atmospheric pressure.

The aforementioned adoption of the atmospheric pressure is beneficial for the simplicity and the reliability of the heat transfer arrangement. There are also some additional benefits, originating from the adoption of the proposed method, which benefits can be materialized by a number of novel arrangements, included in this invention, which will be discussed in a later part of this description. The working principal of this invention is as follows: At first, a pump receives cold cooling liquid ("primary coolant") from a source which, preferably, is a still, remote heat exchanger, located on the pylon or even on the ground. This aforementioned pump transfers the primary coolant, through a pipe, at a selected location (at a high point of the pylon) where the coolant is being ejected (and, preferably, sprayed) from the pipe through an appropriate nozzle or injector. This ejected coolant meets (under ambient pressure) a selected hot surface or mass (the thermal carrier) which is connected to the nacelle - and said thermal carrier carries (through its mass) the heat loads originating from the operation of the turbine (i.e. friction between the gearbox elements) and/or the power generation systems (electric resistances).

The result from the contact between the liquid coolant and the thermal carrier is the decrease of the temperature of the thermal carrier with a corresponding increase of the temperature of the coolant. Being under atmospheric pressure and after got heated, the coolant flows away from the thermal carrier and (preferably under gravity, through pipes) it is transferred to the remote heat exchanger wherein it dumps its head load.

With this method, a reliable transfer of the heat loads (from the operating systems of the nacelle to the remotely located still heat exchanger and, therefore, to the surrounding environment) is performed without any need for direct mechanical connection between the cooling piping of the exchanger and the exposed part of the nacelle which consists the thermal carrier.

According to specific needs (which are different from case to case) the thermal carrier can be a heat exchanger inside of which flows a liquid called, hereinafter, as "nacelle coolant". This nacelle coolant can be the lubricant from the gearbox or/and any other intermediate liquid which carries heat loads from the (electric or mechanical) power generation systems of the wind turbine. There is, sometimes, the need to cool the electric systems of the power generator without the existence of an intermediate, nacelle coolant. In this case, the present invention proposes the placement of these hot electric systems at an appropriate point where they meet (in the form of the aforementioned thermal carrier) the flowing stream of the primary coolant while it is being ejected from the aforementioned injector or nozzle. The result of the continuous wetting, by the primary coolant, of a selected, exposed surface of these electric systems, is the decrease of the temperature of the surface and, accordingly, the removal of heat loads from its contents.

At the case where the heat transfer from the turbine/generator of die nacelle to the heat carrier is being performed by a liquid (nacelle coolant) of the same substance to the liquid of the remote heat exchanger (primary coolant) and, additionally, the (permanent or temporary) mixing of these two liquids is acceptable, then it is feasible (and proposed by an embodiment of the present invention) to have a novel arrangement wherein the thermal carrier is nothing else than the liquid which transfers heat loads from the nacelle (nacelle coolant). In this case, the liquid primary coolant is being ejected on (and inside) the liquid coming from the nacelle, forming a mixture of these two liquids. This mixture, obviously, has a temperature lower than the temperature of the liquid which is coming from the nacelle and, also, a temperature higher than the temperature of the liquid coming from the remote heat exchanger. Immediately afterwards, one part of this mixture is being transferred to the nacelle, as the nacelle coolant and another part of this mixture is being transferred to the remote heat exchanger wherein it dumps its heat load.

A characteristic of the present patent is the existence of a device called, hereinafter, as "heat bowl" wherein, under ambient pressure, a temporary accumulation of the hot coolant after its contact with the thermal carrier, is performed. The aforementioned condition "under ambient pressure" (according to the contact with the thermal carrier), remains the principal characteristic of this invention in its every alternative embodiment according to its spirit. The existence of the heat bowl, according to the present invention, can be utilized beneficially even in the case where the thermal carrier is not a solid object but a liquid medium which is insoluble into the primary coolant and forms a separation surface with it. In this case it is technically feasible to perform a selective pumping of these two liquids (separately) from the heat bowl resulting to their complete separation via any method known from the technical level. For example, this separation can be performed through two (at least) outflows located in selectively different heights of the heat bowl or through one or more outflow pumps from which at least one is located at the bottom of the heat bowl or it is floating over the free surface of its liquid content.

BRIEF DESCRIPTION OF THE DRAWINGS hi figures 1-4 are shown some alternative appliances of the present invention and, specifically, some "connections" (without the need of a physical contact) between a moving (in respect to the pylon) part of the nacelle -which part carries thermal loads to the aforementioned "meeting point"- and the static part of the pylon through which part the thermal loads of the nacelle are being transferred to the still heat exchanger.

In figures 5 and 6 are shown some novel configurations through which it is feasible to utilize the great height of the pylon in order to improve the efficiency of the system. In figures 7a and 7b are shown, schematically, the longitudinal layouts of two different shapes of thermal carrier, according to the spirit of the present invention.

In figures 8a and 8b are shown the longitudinal layouts of two alternative embodiments of a special arrangement for the co-operation between the thermal carrier and the heat bowl, according to the spirit of the invention. In figure 9 is shown, schematically, an embodiment of the present invention where the thermal carrier and the heat bowl compose a structurally unified element.

In figure 10 is shown an indicative appliance of principal elements, belonging to mis present invention, which are located at a place outside the pylon.

In figure 11 is shown the elementary presentation of a wind turbine of the horizontal rotor-shaft type, according to the known technical level. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In figure 1 is shown, indicatively, a suggested arrangement through which a first embodiment of this invention is materialized. The main cooling circuit starts from the still heat exchanger (1) which is securely attached either on the pylon (and, preferably, at a lower point of it) or at a location near to the wind generator but apart from it. Through the inlet point of the still heat exchanger (1) enters a cooling liquid (primary coolant) of increased temperature, which liquid transfers heat load originating from the power generating devices of the wind turbine. Through the outlet of the still heat exchanger comes out the aforementioned primary coolant which is, now, of lower temperature after its passing through the exchanger.

In this present drawing it is shown, schematically, the still heat exchanger in its simplest configuration. Presumably, it is understandable that in the practical appliances of this present invention, this heat exchanger is being accompanied by supplementary devices (omitted from this figure, for simplicity reasons) which devices are known from the technical level and perform a supporting to the exchanger function. Some devices of this kind, for example, are a coolant tank of sufficient capacity which is used as "peak load absorber" (functioning as a thermal buffer or heat sink, according to the way of its utilisation) or a ducting configuration which is, partially, by-passing the heat exchanger (or sort-circuiting the heat exchanger, by the reintroduction into its inlet of a portion of the coolant which is exiting from this) in order to avoid the icing of the coolant. All these aforementioned supporting devices are accompanied by additional elements such as mixers, controlled valves, temperature sensors, function control unit etc. Additionally, it is obvious that the connection arrangement of the buffer to the cooling circuit varies according to the existing needs and the desirable results, in any different application case.

At this point, it must be noted again that, according to the existing needs, it is possibly preferable to have a common still heat exchanger for a number of neighbouring wind turbines. This configuration is useful, especially, in case where the heat which is being emitted from the exchanger can be utilized further by appropriate devices. Also, according to the magnitude of the heat load and the specific configuration of each different application, the still heat exchanger can be of a liquid/air type or a liquid/liquid type.

By the exit of the still heat exchanger and via (at least) one pump which is called main pump (2), a pipe, called main coolant pipe (4) is supplied with low temperature coolant, named hereinafter, as primary coolant. Via said main coolant pipe (4) which extents at a suitable height of the pylon, the primary coolant is transferred to (at least) one outlet of the main coolant pipe which outlet is called, hereinafter, as main coolant nozzle (3). Through said main coolant nozzle (3), the main coolant is being ejected (and preferably, sprayed), under ambient temperature, against the exposed surface of the aforementioned thermal carrier (100) of the wind generator, resulting in cooling of this "wetted" surface under atmospheric pressure. The thermal carrier (100), which is moving simultaneously with the nacelle, at its continuous reorientation, can be of any appropriate structure and shape, according to each specific application. It can be, for example, a heat-conductive unit which carries, in its inside, power controlling electric circuits. Therefore, the parasitic heat, which is originated in the inside of the unit, is being transferred to the surface where it is absorbed by the main coolant which is flowing over it. In another example, the exposed surface of the thermal carrier is the outer surface of a heat exchanger inside of which there is a circulation of a hot fluid (nacelle coolant) which must be cooled accordingly. This hot fluid can be the lubricant of the wind turbine gearbox or any other fluid which is circulating inside certain places of the nacelle and, via its elevated temperature, transfers heat load to the thermal carrier.

After the wetting of the exposed surface of thermal carrier, the cooling liquid (the primary coolant) outflows from the thermal carrier and (preferably, with the help of the gravity) arrives, under atmospheric pressure, to a collection basin, called henceforth heat bowl (12), from where it is transferred again into the heat exchanger via the outflow pipe (10) or to the environment if the system is of the "total loss" type. As it will be described afterwards (and according to each specific application of the present invention), in a first embodiment, the heat bowl is fixed on the pylon and, in consequence, it remains motionless respectively to the rotating nacelle. Alternatively, the heat bowl is suspended from the nacelle and it is turning simultaneously with it, in respect to the motionless pylon.

The desirable distance of the thermal carrier surface from the free surface of the liquid which is accumulated inside the heat bowl, is regulated according to specific needs originating from any certain embodiment of the present invention. The height of the free surface of accumulated primary coolant inside the heat bowl can be adjusted either through a strategically located opening (for an overflow exit) on the heat bowl or, through any other (usually, known from the technical level) suitable method, which is based upon a regulated inflow/outflow. Under certain circumstances, it is not prohibited, by the present invention, to have the thermal carrier immersed (partially or, even totally) inside Ae liquid content of the heat bowl. In this case, obviously, it is necessary to have a fail-proof provision for the avoidance of the freezing of the coolant, inside the heat-bowl, whenever the wind turbine is performing a temporary "emergency stop".

In figure 2 is portrayed a henceforth complex embodiment of the present invention. In this case, a part of the cooling liquid which is collected (under ambient pressure) inside the heat bowl (12), is rerouted to (at least) one secondary coolant nozzle (3A) via the secondary pump (2A) which draws liquid from the interior of the heat bowl (12). This liquid which is coming from the heat bowl (12) is of relatively higher temperature than that of the primary coolant which comes out from the still heat exchanger (1) since it is a mixture of cold primary coolant (coming directly from the still heat exchanger) and of hot primary coolant coming from the wetted surface of the thermal carrier (100). As it can be noticed in figure 2, there are portrayed (indicatively) two cooling nozzles (3), connected to the main coolant pipe (4). From which these two (at least) nozzles, the first nozzle sprays the surface of the thermal carrier (100) while the second outflows directly inside the interior of the heat bowl (12) without its flow coming, necessarily, in contact with the hot surface of the thermal carrier. It is obvious that the present invention has the ability to operate with either one of these two described alternative versions (according to the orientation of cooling nozzles) or even with the combination of these versions, depending on the operating conditions of the system (and the environmental conditions, also) and the magnitude of the heat load that must be transferred to the environment. When the transferable heat load is of a small magnitude, then it is feasible to reduce the energy consumption for the operation of the main pump (2). This can be achieved in the case where the main pump does not feed (temporary or always) with primary coolant any nozzle which is spraying the surface of the thermal carrier. As it can be seen in figure 2, there is a cooling nozzle (3) which outflows directly inside the heat bowl (12) and this nozzle is being fed by the main pump (2). (The flow to this cooling nozzle, can be adjusted according to the desired result - and this can be accomplished, for example, either by increasing/decreasing of a continuous flow of coolant either by the appropriate controlling of an intermittent flow, according to the signal of a temperature sensor). On the other hand, there is a secondary pump (2A) (which is located at an appropriate height relatively to the pylon - here, it is shown, indicatively, inside the heat bowl) feeds at least one secondary cooling nozzle (3A) which poures out coolant (consisting of a mixture of hot and cold coolant, collected from the heat bowl) on the exposed surface of the thermal carrier (100). In figure 3 is shown a different embodiment of the same, present invention wherein the turning heat carrier (100) is accompanied by a heat bowl (12) which is suspended from the nacelle and, consequently, moves together with it during the continuous reorientation of the wind turbine. In this case, the main coolant nozzle (3) is able either to spray, directly, onto the thermal carrier (100) or, alternatively, it is dedicated to supplement, with primary coolant, the content of the rotating heat bowl (12). This second solution is, suggestively, combined with the presence of an auxiliary pump (2A) which supplies with a mixture of hot and cold coolant a secondary coolant nozzle (3A) which wets the exposed surface of the thermal carrier. An outflow pipe (10) is channeling the overflowing fluid from the heat bowl to a selected point of coolant circuit (and, preferably, the pipe which feeds, with hot coolant, the still heat exchanger).

As it is mentioned previously (according to figure 2), the main pump (2) of figure 3 is possible to supply with primary coolant more than one primary coolant nozzles (3) from which one or more will spray coolant on the surface of thermal carrier and the rest will pour coolant directly in the heat bowl (12).

In some embodiments which are already described, the thermal carrier has the structure of a solid heat exchanger of the "liquid/liquid" type. In this case, a stream of low temperature cooling liquid is coming in contact with the solid outer surface of the heat exchanger but not directly with the liquid means (nacelle coolant) which are flowing inside this heat exchanger/thermal carrier (and which liquid, in fact, is the actual means which transports the heat loads from the nacelle). On the other hand, and remaining inside the spirit of the present invention, it is feasible to have a direct contact between these two aforementioned liquids, in a certain embodiment of the present invention. In this case, it is possible to increase the efficiency of the system regarding the transport of heat loads from the moving ("belonging" to the nacelle) to the still ("belonging" to the pylon) part of the cooling system of the wind generator.

In figure 4 is shown an application of the present invention through which is rendered feasible the direct contact of the primary coolant with the fluid means that transfers the heat loads from the nacelle to the "meeting point" of the thermal carrier. The hot liquid that emanates from the nacelle (the nacelle coolant) is transferred in the heat bowl (12) via a down flow pipe (20), and outflows inside the heat bowl through the down flow exit (21) wherein it is mixed with the cold primary coolant which outflows from an appropriate primary coolant nozzle (3). Afterwards, the mixture of nacelle coolant and primary coolant is reintroduced to the nacelle with the help of a recirculation pump (22). As it is understandable, in this particular case, the element which functions as thermal carrier (100) is composed by the down flow exit (21), the recirculation pump (22) and the mass of the fluid means mat is interfered between the down flow exit (21) and the recirculation pump (22). Practically, the sum of the aforementioned parts, including the primary coolant nozzles (3), consists, practically, a heat exchanger of the "liquids mixing" type.

In this particular drawing (figure 4) the heat bowl (12) is shown as not suspended from the nacelle. Li this case, where a still heat bowl (attached on the pylon) is preferred, it is obvious that the secondary pump (2A) could be, preferably, be suspended from the nacelle, being kept immersed in the liquid content of the heat bowl. On the other hand, it is profoundly feasible, if it is so desired, to have the heat bowl (12) suspended from the nacelle, rotating simultaneously with it, during the reorientation of the wind turbine. Consequently, the secondary pump (2A) can be attached, securely, on the heat bowl (12). In any case, an outflow pipe (10) is carrying the overflowing cooling liquid from the heat bowl (12) to an appropriate point of the primary coolant circuit and preferably, the entrance of the still heat exchanger (1). There is a case where the two functioning liquids of the arrangement shown in figure 4 (the first of them is the primary coolant and second is the nacelle coolant which circulates inside the systems of the nacelle) cannot be mixed but, on the contrary, they form a separation surface between them - this condition exists, for example, when the coolant of the nacelle is a water-based solution and the primary coolant is an organic substance of a low-freezing point or vice versa. In this case, the arrangement shown in fig, 4 can be operational provided that there is provision for the separation of these two fluids - with the help, as an example, of a floating pump forme removal of the less dense of the two fluids and a sunk (in suitable depth) outflow opening through which the more dense fluid will be removed form the heat bowl (with the help of a special pump or a siphon or any other suitable provision provided from the technical level). For reasons of safety, it is preferable that, after their exit from the heat bowl and before their return to corresponding hydraulic circuits, each one of the two aforementioned liquids must pass through an appropriate separator in order to get rid of traces from the other liquid. In any case, the most satisfactory embodiment of the alternative arrangement which just have been described can be realized using the same type of liquid for the two aforementioned cooling mediums - for example, water mixed with anti-freezing agent. In this case, the coolant which is circulating inside the nacelle is able to remove heat from one or more individual elements of the nacelle (par example, the lubricating system of the gearbox or the heat sinks of the power electronics) through local, secondary heat exchangers.

In figure 5 is shown, schematically, a proposed embodiment of the present invention wherein it is performed the heat removal (partially or totally) from the coolant which overflows from the heat bowl (12) and which said heat bowl is either still, attached on the pylon, or rotating, suspended from the nacelle. The coolant flows through the outflow pipe (10) and is channelled to the pouring outflow (11) from where it is left to fall inside the internal space of a vertical air duct (9) and, finally, it is collected (flowing due to the gravity) by a suitable provision (called, hereinafter, as coolant collector) located at the bottom of said vertical air duct. The presence of a coolant collector (120) which is feeding with coolant a coolant storage tank or an accumulator or a still heat exchanger (not shown any of them) enables the primary coolant to enter inside the aforementioned units under, approximately, ambient pressure - a fact that simplifies the structure of these units of the coolant circuit. In the case where the heat bowl is suspended from the nacelle, it is, sometimes, preferable to have the exit of the pouring outflow (11) positioned as nearer as possible to the vertical axis of rotation of the nacelle/heat bowl ensemble (to avoid spraying, with coolant, the surrounding surfaces, in the case where it is considered necessary to avoid). The said vertical air duct (9) can be either the pylon of the wind turbine or a separate duct, located inside the pylon and, according to each different embodiment of this invention, it can be attached on the pylon or, alternatively, it can be suspended from a suitable extension of the nacelle. In case where the attachment of the vertical air duct (9) to the nacelle is performed through a rigid connection (and not through an appropriate bearing) then the vertical air duct (9) is rotating, inside the pylon, at the reorientation of the nacelle to the wind direction.

Inside the vertical air duct (9) a stream of air is moving, upwards. This stream of air is either prompted from the pressure difference originated from the difference of height between entry openings (50A) and exit openings (50B) or it is enforced from a cooling fan (500) or from a suitable combination of the two aforementioned methods. The motion of the cooling fan (500) can be derived either directly from the wind turbine or from a small, auxiliary, wind turbine - preferably, dedicated to this, certain operation. In this last case, it is feasible to have an almost satisfactory harmonisation between the produced parasitic heat loads in the "main" wind turbine (which loads are increasing in connection with the intensity of wind) and the output of the auxiliaiy wind turbine unit which moves the cooling fan.

In a simplified version of the present invention, this aforementioned presence and operation of the vertical air duct (9) is able to substitute, completely, the operation (even, also, its presence) of the still heat exchanger (1). Obviously, the presence and operation of the vertical air duct (9) can be incorporated (as the main or auxiliary cooling unit) in any other embodiment of this invention which have been already described. The aforementioned facts are in effect, also, in the case of figure 6 where the hot cooling liquid, coming from the pouring outflow (11), ends inside a coolant collector (120), located at an elevated point of the pylon, from which coolant collector begins a vertically positioned still heat exchanger (1), of the "liquid/air" type, which is located, longitudinally, inside the vertical air duct (9). This arrangement operates (regarding the movement of air) with similar alternative ways which have been already described according to the installation shown in figure 5. This vertical heat exchanger can be the exclusive still heat exchanger of the cooling system or, alternatively, it constitutes a complementary element of a second still heat exchanger which, potentially, can be found in a different point of the cooling circuit, even in a distance from the pylon.

According to the arrangement shown in figure 6 it is obvious that, remaining inside the spirit of the invention, it is feasible (but not practically preferable, in most cases) to have a more simplified form of cooling apparatus if the intermediate coolant collector (120) is omitted and the heat exchanger (1) is attached directly to the heat bowl (12).

In figure 7a is shown a thermal carrier (100) the exterior surface of which is thus shaped so mat it can retain, temporarily, the coolant with which it is being wetted by at least one primary coolant nozzle (3) or by at least one secondary coolant nozzle (3A) or by a combination of these. This provision can be composed in a variety of forms arising profoundly from the spirit of this element of the present invention. Particularly, in figure 7a, is shown a form composed from (shown enlarged, proportionally) multiple annular canals (100A) which withhold the sprayed cooling liquid up to its overflow from the upper lips of the canals. In another embodiment, there can be formed a single helical canal which surrounds the thermal carrier and inside which canal the cooling liquid flows, due to its gravity, until the lower point of the canal - therefore, the coolant drops inside the heat bowl. As it is said previously, there is, practically, no limit to the number of possible alternative forms (cavities, canals etc.) of the outer surface which forms enable the exposed surface of the thermal carrier (100) to retain sprayed coolant on it. In figure 7b is shown a thermal carrier (100) the internal structure of which is formed with multiple running-through passages (100B) inside of which flows, due to the gravity, the cooling liquid which outflows from the spraying nozzles (in the figure is shown a primary coolant nozzle [3] and this nozzle can be accompanied with any number of primary or secondary coolant nozzles, if it is necessary). In this indicative embodiment, the cooling liquid runs through the mass of the thermal carrier coming in contact with considerably greater surface than in the previously described embodiments.

In the case where the rotating thermal carrier has the form of a heat exchanger of the "liquid/liquid" type and this heat exchanger is immersed in capable depth inside the cooling liquid which is accumulated inside the heat bowl, then is feasible the creation of a henceforth simplified arrangement, compared to those that are shown in figures 1, 2 and 3. In figure 8a is shown a first version of this proposed arrangement in combination with a motionless heat bowl (12). In this case, at least one primary coolant nozzle (3) (here, is only one portrayed) is supplying with cooling liquid (primary coolant) exclusively the heat bowl (12) wherein the thermal carrier (100) is immersed. An outflow pipe (10) transports the overflowing fluid from the heat bowl (12) to a "starting point" of the cooling circuit. As it is understandable, the existence in this embodiment of supplementary nozzles which spray coolant on the surface of the thermal carrier is not necessary, in most situations.

In figure 8b is shown a similar arrangement with that of figure 8a with the difference that, in this case, the heat bowl (12) is attached to the thermal carrier (100) and it is rotating simultaneously with it, during the reorientation of the nacelle. The exit of the outflow pipe (10) pours hot coolant, preferably by gravity, inside an appropriate coolant collector (120). According to the cooling circuit mat follows, this collector (120) is either a "high placed" collection bowl (as shown in fig. 6) or a bottom collector as shown in fig. 5 or a combination of these two, according to the desired hydrostatic pressure in certain locations of the cooling circuit. In figure 9 is shown a complex application, arising from the application that is already shown in figure 8b. According to this embodiment, the thermal carrier (100) is incorporated, structurally, in the mass of the mobile heat bowl (12) composing, with it, a unified element. This embodiment is considered as most effective in the case where the thermal carrier has the form of a heat exchanger in the interior of which is circulating a hot liquid emanating from the nacelle - and, after the desired reduction of its temperature, inside the thermal carrier, this liquid is returning in the nacelle. As an example, mis liquid can be the lubricant of the gearbox of the wind generator or the cooling liquid of a separate heat exchanger (incorporated into the nacelle) which liquid transports, to the thermal carrier, heat loads produced in one or more "hot spots" of the wind turbine.

For reasons of simplicity all the alternative embodiments of the present invention which are described up to this point, are shown with their main functional elements located inside the pylon. Obviously, mis condition is not obligatory - on the contrary, there are cases where it is preferable to arrange the main elements of this invention outside the pylon, in order to leave its inner space (and, especially, the top) free from liquid carrying elements.

In figure 10 is shown, indicatively, an embodiment of the present invention where the elements of an arrangement which is similar to these shown in figures 2 and 8a, are installed outside the pylon. In this case, the heat bowl (12) has, preferably, the shape of a ring, rigidly connected to the pylon. As a result - and independently of any momentary position of the nacelle, during its reorientation towards the wind -, the heat carrier (100) is always above a portion of the heat bowl (12) or (if it is so desired) immersed inside it. In case where the ring-shaped heat bowl (12) is stationary, rigidly attached to the pylon and there is, also, a secondary pump (2A in previous drawings - not shown in figure 10) this pump must be attached, preferably, to the thermal carrier (100), following it during its movement inside the stationary heat bowl (12). Alternatively, it is obvious that the ring-shaped heat bowl (12) can be attached to the nacelle, rotating with it during the re- orientation of the wind turbine, as, par example, is shown in figure 3 or in figure 8b. In this last case, the collection of the overflowing coolant from the heat bowl can be performed, profoundly, through an appropriately shaped coolant collector (120 in figure 8b - not shown in figure 10) which is attached around the pylon.

As it is obviously understood, any alternative embodiment of the present invention, which is already described (and, especially, that shown in figure 4) can be modified accordingly in order to fit to a situation where a ring-shaped heat bowl (12) is located outside the pylon.

While the invention has been illustrated and described in connection to currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. The embodiments were chosen and described in order to best explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.

Claims

1. Cooling apparatus for wind tuibine of horizontal axis via which provision is facilitated the expulsion of heat loads from the wind turbine to the environment and which wind turbine is constituted from a nacelle (1001), rotating around a vertical axis, and from a vertical pylon (1002) on the top of which pylon is located the nacelle (1001), which nacelle brings a power generating system consisting of electromechanical units for the transformation of wind energy to electric energy, with simultaneous production of heat energy due to the mechanical frictions and electrical resistances inside the power generating system and this cooling apparatus is constituted from a still part, composed of elements that are attached to the pylon (1002) and its surrounding environment and from a moving part, composed of elements that are attached to the nacelle (1001) which nacelle rotates around a vertical axis during its reorientation to die variable direction of the wind, where the still part of cooling apparatus is constituted from at least one source of low temperature coolant which source, preferably, is a still heat exchanger (1 ), at least one pump for liquids, named hereinafter as main pump (2), at least one main coolant pipe (4) and at least one main coolant nozzle (3) where through the inlet of still heat exchanger (1) enters cooling liquid transporting heat loads which loads are being removed by the still heat exchanger (1) and transferred to the environment so from the exit of the heat exchanger (1) comes out cooling liquid, named, hereinafter, as primary coolant, which primary coolant has, at the exit of the heat exchanger (1) lower temperature than the one that had just before its entry in the heat exchanger (1) and the exit of said heat exchanger (1) supplies with primary coolant the entry of main pump (2) which pump forces the primary coolant inside the main coolant pipe (4) which pipe is attached to the pylon (1002), carrying primary coolant up to a suitable height of the pylon (1002) and said main coolant pipe (4) ends to at least one main coolant nozzle (3) and the moving part of cooling apparatus is constituted from an apparatus through which heat loads originating inside the nacelle (1001) are being transferred to a suitably shaped element, called henceforth as thermal carrier (100) and which thermal carrier (100) is exposed, directly or indirectly, to the primary coolant resulting so in the temperature decrease of the thermal carrier (100) and, subsequently, the temperature increase of the primary coolant and said thermal carrier (100) can be, alternatively, either a solid mass inside which there is a flow of heat energy from its hotter points to the points with a lower temperature and the final rejection of said heat energy is performed through the exposed surface of the thermal carrier (100) or a solid mass with exposed exterior surface and which mass is shaped as a heat exchanger inside of which exists a enforced flow of one fluid named hereinafter as nacelle coolant which nacelle coolant is transferring heat loads between the solid surfaces with which it is coming in contact, or, finally, an exposed to the environment flow of a fluid transferring heat loads from the nacelle (1001) and returning to the nacelle (1001) after its direct contact with suitable amount of primary coolant and is characterized in that the low temperature primary coolant that runs through the static part of cooling apparatus is led to at least one main coolant nozzle (3) through which it outflows, under the pressure of main pump (2), and in that the primary coolant which outflows from a main coolant nozzle (3) covers a distance in environment of ambient pressure, arriving, finally to the mass of the thermal carrier (100) with which mass it comes in contact under ambient atmospheric pressure.

2. Cooling apparatus of wind turbine, according to the claim 1, characterized in that the thermal carrier (100) has solid form and in that the primary coolant which outflows from the main coolant nozzle (3) is being sprayed directly on the exposed surface of the thermal carrier (100), cooling it.

3. Cooling apparatus of wind turbine, according to the claim 1, characterized in that at least, a part of the primary coolant which outflows from the main coolant nozzle (3) flows, due to gravity and under atmospheric pressure, to a basin of collection, henceforth called as heat bowl (12) and in that the surplus of the coolant which accumulates inside the heat bowl (12) is removed through at least one outflow pipe (10).

4. Cooling apparatus of wind turbine, according to the claims 1 and 3, characterized in that the thermal carrier (100) has solid form and is, partially or totally, in direct contact with the cooling liquid that is accumulated inside the heat bowl (12).

5. Cooling apparatus of wind turbine, according to the claims 1 and 3, characterized in that a secondary pump (2A) draws cooling liquid from the heat bowl (12) and channels this cooling liquid into a secondary coolant nozzle (3A) and in that the secondary coolant nozzle (3A) sprays cooling liquid on the surface of the thermal carrier (100).

6. Cooling apparatus of wind turbine, according to the claims 1 and 3, characterized in that a down-flow pipe (20) which ends to a down-flow exit (21) transports, from the nacelle, hot fluid named hereinafter nacelle coolant, which nacelle coolant flows, through the down-flow exit (21 ), into the heat bowl (12) wherein it remains under ambient temperature, in that inside the heat bowl (12) exists the entry of a recirculation pump (22) via which pump is drawn the fluid from inside the heat bowl (12) and is reintroduced into the nacelle, in that at least one main coolant nozzle (3) adds primary coolant inside ihe heat bowl (12) which primary coolant is added to the mass of the fluid content of the heat bowl (12) resulting in a corresponding reduction of its temperature so that the portion of the liquid which is accumulated inside the heat bowl (12), between the flow from the down flow exit (21) and the recirculation pump (22), functions as thermal carrier (100) and in that a regulated quantity of fluid outflows from the heat bowl (12) and is transferred away through an outflow pipe (10).

7. Cooling apparatus of wind turbine, according to the claims 1 and 3, characterized in that the thermal carrier (100) is a heat exchanger inside of which circulates nacelle coolant and in that this certain thermal carrier (100) constitutes a single structural unit together with the heat bowl (12) inside of which one, at least, main coolant nozzle (3) pours primary coolant.

8. Cooling apparatus of wind turbine, according to the claims 1 and 3, characterized in that the liquid which outflows from the heat bowl (12) through an outflow pipe (10), is sprayed inside a vertical air duct (9) wherein the said liquid runs through an air stream of lower temperature than the temperature of the sprayed liquid.

9. Cooling apparatus of wind turbine, according to the claim 8, characterized in that the liquid which outflows from the heat bowl (12) through an outflow pipe (10), is sprayed inside a vertical air duct (9) wherein the said liquid pours, due to gravity, downwards against the direction of the stream of air which is flowing upwards and in that the cooled liquid, at the end of the distance which it travels through the air stream, is collected in a coolant collector (120).

10. Cooling apparatus of wind generator, according to the claimsl and 3, characterized in that the liquid which outflows from the the heat bowl (12), through an outflow pipe (10), is transferred inside a heat exchanger, of the "air/liquid" type, which exchanger is located inside a vertical air duct (9), inside of which vertical air duct (9) there is an air stream of lower temperature than the temperature of said liquid.

11. Cooling apparatus of wind generator, according to the claimsl and 3, characterized in that the heat bowl (12) is located inside the pylon.

12. Cooling apparatus of wind generator, according to the claimsl and 3, characterized in that the heat bowl (12) and the thermal carrier (100) are located outside the pylon.

13. Cooling apparatus of wind generator, according to the claim 12, characterized in that the heat bowl (12) is ring-shaped, surrounding the pylon (1002) near the top of it.

14. Cooling apparatus of wind generator, according to the claims 5 and 13, characterized in that at least one secondary pump (2A) is attached to the thermal carrier (100).

15. Cooling apparatus of wind generator, according to the claims 6 and 13, characterized in that at least one recirculation pump (22) is attached to the thermal carrier (100) and in that at least one down flow pipe (20), which ends to a down flow exit (21), is attached to the thermal carrier (100).