Patent Description:
Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modem wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known foil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid. <CIT> and <CIT> relate to multisiphon passive cooling systems.

Many known devices (e.g., generators, rectifiers, inverters and transformers) are used for conversion of electric power. Rectifiers are used for converting alternating current (AC) to direct current (DC) and inverters are used for converting DC current to AC current. Typically, rectifiers and inverters are integrated into full power conversion assemblies (i.e., power converters) used in renewable electric power generation facilities such as solar power generation farms and wind turbine farms. These devices typically generate large amounts of heat during power generation. At least some known power generating devices use a liquid cooling system for cooling the main heat-generating components. These liquid cooling systems include an active pump for pumping a working liquid for cooling the power devices, and these systems may also include fans and valves. In such a system, maintaining a flow rate of the working liquid in two or more branches of the liquid cooling system may be problematic due to high resistance to a flow of the working liquid in some branches in comparison to low resistance to the flow of the working liquid in other branches.

A liquid cooling system employing pumps, fans and/or valves is classified as an active system. The term 'active' referring to the mechanical action performed by the pump to circulate the liquid cooling medium, or the forced airflow by the fan. All active systems require periodic maintenance, and this is critical for system reliability. For example, if a pump fails then the entire cooling system will fail to satisfactorily cool the heat-generating components. This is especially problematic for off-shore wind turbines that have limited opportunities for access and maintenance.

In one aspect, the present disclosure is directed to a passive cooling system. The passive cooling system includes a heat exchanger thermally coupled to a heat-generating component located within an enclosure, a distribution manifold located below the heat exchanger, a condensing unit located external to the enclosure and above the heat exchanger, and a first conduit thermally connected to the heat exchanger. The first conduit is fluidly connected to the distribution manifold and the condensing unit. The cooling system also includes a second conduit fluidly connected to the condensing unit and the distribution manifold, a liquid bridge fluidly connected to the first conduit and the second conduit or the distribution manifold, and a two-phase cooling medium that circulates through a loop defined by the first conduit, the liquid bridge, the condensing unit, the second conduit, the heat exchanger, and the distribution manifold. As such, the liquid bridge transfers the cooling medium in a liquid state from the first conduit to the second conduit or the distribution manifold.

In an embodiment, the cooling system may include a plurality of heat exchangers thermally connected to a plurality of heat-generating components and a plurality of first conduits connected in parallel between the distribution manifold and the condensing unit. In such embodiments, each of the plurality of first conduits may be fluidly connected with one of the plurality of heat exchangers. In another embodiment, the cooling system may include two or more heat exchangers connected in series along one of the first conduits.

In further embodiments, the cooling system may also include a plurality of liquid bridges fluidly connected to the plurality of first conduits and the second conduit or the distribution manifold.

In additional embodiments, one of the plurality of liquid bridges may be fluidly connected to each of the plurality of first conduits and the second conduit or the distribution manifold.

In certain embodiments, the liquid bridge may be a tubular member positioned at an inclined angle between the first conduit and the second conduit or the distribution manifold. In alternative embodiments, the tubular member may include at least one trap.

In an embodiment, the enclosure may include a nacelle of a wind turbine or a solar power system. In such embodiments, the condensing unit may be secured atop the nacelle. In another embodiment, the heat-generating component(s) may include a generator rotor, a generator stator, a gearbox, a transformer, an inverter, a converter, or combinations thereof. In still further embodiments, the cooling system may be absent of a pump or fan within the enclosure.

In another aspect, the present disclosure is directed to a wind turbine. The wind turbines includes a tower, a nacelle mounted atop the tower and defining an enclosed internal volume, a rotor mounted to the nacelle and having a rotatable hub and at least one rotor blade mounted thereto, at least one heat-generating component positioned within the internal volume of the nacelle, and a passive cooling system for cooling the internal volume of the nacelle. The cooling system includes a heat exchanger thermally coupled to the at least one heat-generating component, a distribution manifold located below the heat exchanger, a condensing unit located external to the nacelle and above the heat exchanger, a first conduit fluidly connected to the heat exchanger, the distribution manifold, and the condensing unit, a second conduit fluidly connected to the condensing unit and the distribution manifold, a liquid bridge fluidly connected to the first conduit and the second conduit or the distribution manifold, and a two-phase cooling medium that circulates through a loop defined by the first conduit, the liquid bridge, the condensing unit, the second conduit, the heat exchanger, and the distribution manifold. Thus, the liquid bridge transfers the cooling medium in a liquid state from the first conduit to the second conduit or the distribution manifold. It should be further understood that the wind turbine may also include any of the additional features described herein.

In general, the present disclosure is directed to a multisiphon cooling system having at least one liquid bridge for cooling heat-generating components. The cooling system described herein may be particularly suitable for a wind turbine. Though, it should be understood that the cooling system may also be suitable in additional applications, including but not limited to solar, hydro, energy storage, and the like or combinations thereof.

Generally, a thermosiphon generally refers to is a passive single-phase or a two-phase cooling system where heat is dissipated from an electrical machine or electronic component by phase change from liquid to vapor (e.g. boiling). The liquid-vapor mixture rises up passively due to buoyancy, to a condenser where the mixture is returned to liquid form and flows down to a heat-generating component again due to gravity. This cycle continues to passively remove heat from the component. In the present disclosure, this concept is extended to multiple heat-generating components, each having a heat exchanger associated therewith, that are connected in a parallel/series configuration to form a passive, high heat transfer cooling system (referred to as a multisiphon). In an embodiment, the cooling system may be completely passive and thus may not require a pump or fan to circulate a cooling fluid therethrough e.g. within the enclosure. Thus, by providing a multisiphon system to a wind turbine machine head, pumps and/or blowers may be eliminated, and heat exchanger sizes may be reduced, thereby lowering the overall volume and weight of the machine head. Moreover, additional power is not required to circulate the cooling fluid. In this manner, the cooling system described herein is reliable and requires little, if any, maintenance.

Aspects discussed herein disclose a cooling and heat dissipation system having a thermosiphon including one or more cooling loops, where each cooling loop includes at least one heat exchanger thermally coupled with a heat-generating component. Such a cooling system may be used for thermal management of a power converter, an inverter, a transformer, a gearbox, or a generator, e.g. of a wind turbine, solar power system, etc. Additionally, the cooling and heat dissipation system may be used for thermal management of a hermetically sealed motor (e.g., a pitch or yaw drive) or the like. The cooling system includes a first conduit, a condensing unit, a second conduit, a distribution manifold, and at least one liquid bridge all connected into a loop. The liquid bridge refers to a fluid connection between the rising liquid-vapor column (riser) from the evaporator and the descending liquid condensate column (downcomer). Thus, the liquid bridge serves to separate the liquid from the rising liquid-vapor mixture and returns this liquid to the inlet side. The liquid bridge also lowers pressure drop in the system by providing parallel pathways for the fluid. The liquid bridge can be a single plain tube inclined at an angle and connecting the riser and down-comer or multiple bridges at least one per heat source (e.g. an evaporator). The bridge could also be enhanced with one or more traps, such as a P-trap, to improve liquid-vapor separation. In addition, the liquid bridge of the present disclosure may also reduce the total coolant mass flow rate flowing through the evaporator, and thus reduce the evaporator thermal duty, thereby reducing its size and/or cost.

The condenser is disposed above the first and second conduits and heat exchangers associated with the heat-generating components. It should be noted herein that the term "above" as used herein means the condenser is physically located at a higher location with respect to the first conduit and the heat-generating components. Thus, the condensing unit is used to receive a two-phase fluid from the first conduit and dissipate the extracted heat to an ambient atmosphere to produce a single-phase fluid. It should be noted herein that the term "single-phase fluid" refers to a liquid medium. Similarly, the term "two-phase fluid" may refer to a mixture of liquid and gaseous mediums, or a gaseous medium.

Referring now to the drawings, <FIG> illustrates a side view of a wind turbine <NUM>. As shown, the wind turbine <NUM> generally includes a tower <NUM> extending from a support surface <NUM> (e.g., the ground, a concrete pad, offshore platform or any other suitable support surface). In addition, the wind turbine <NUM> may also include a nacelle <NUM> mounted on the tower <NUM> and a rotor <NUM> coupled to the nacelle <NUM>. The rotor <NUM> includes a rotatable hub <NUM> and at least one rotor blade <NUM> coupled to and extending outwardly from the hub <NUM>. For example, the rotor <NUM> may include three rotor blades <NUM> (as shown). However, the rotor <NUM> may include more or less than three rotor blades <NUM>. Each rotor blade <NUM> is spaced about the hub <NUM> to facilitate rotating the rotor <NUM> to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy. For instance, the hub <NUM> may be rotatably coupled to an electric generator (not shown) positioned within the nacelle <NUM> to permit electrical energy to be produced.

Referring now to <FIG>, a schematic view of one embodiment of a passive cooling system <NUM> according to the present disclosure is illustrated. Various components within the nacelle (or enclosure) <NUM> of the wind turbine need to be cooled. For example, such heat-generating components may include a transformer <NUM>, a converter <NUM>, a gearbox <NUM>, or a generator <NUM> (including both the generator rotor and/or the generator stator). The specific components shown in <FIG> are one example only, and nacelles may omit certain heat-generating components or add others. For example, a direct drive wind turbine does not have a gearbox as the rotor is connected directly to the generator, so the gearbox would be omitted in this embodiment. As shown in <FIG>, all the heat-generating components <NUM>-<NUM> are located or housed within the enclosure <NUM>.

Each heat-generating component <NUM>-<NUM> is thermally connected to a first conduit <NUM>', <NUM>", <NUM>‴, and the first conduit is fluidly connected to a distribution manifold <NUM> and a condensing unit <NUM> which is located external to enclosure <NUM> and above the heat-generating components <NUM>-<NUM>. A second conduit <NUM> is fluidly connected to the condensing unit <NUM> and the distribution manifold <NUM>. One or more of the conduits <NUM>, <NUM> contain a two-phase cooling medium that turns gaseous and rises as it heats up by absorbing thermal energy from the heat-generating components <NUM>-<NUM>, and the cooling medium changes back to a liquid state as it cools in the condensing unit <NUM>.

A first loop exists with first conduit <NUM>', transformer <NUM>, condensing unit <NUM>, second conduit <NUM> and distribution manifold <NUM>. A second loop exists with the first conduit <NUM>", the converter <NUM>, the condensing unit <NUM>, the second conduit <NUM> and the distribution manifold <NUM>. A third loop exists with first conduit <NUM>‴, gearbox <NUM>, generator <NUM>, condensing unit <NUM>, second conduit <NUM> and distribution manifold <NUM>. The multiple first conduits <NUM>', <NUM>", <NUM>‴ form parallel flow paths between the distribution manifold and the condensing unit. Individual paths may have heat-generating components connected in series, as shown with first conduit <NUM>'" and the gearbox <NUM> and the generator <NUM>. The cooling medium is in its liquid state in the distribution manifold <NUM>, and the distribution manifold <NUM> is the lowest element in the system as gravity is used to collect and return the liquid cooling medium to the distribution manifold <NUM>. Liquid cooling medium is also present in the lower portions of the first conduits <NUM>', <NUM>", <NUM>'". As the wind turbine <NUM> operates, the heat-generating components <NUM>-<NUM> generate heat that is transferred to the cooling medium. The cooling medium will phase change to a gaseous state and naturally forms a thermosiphon as the gases rise up first conduits <NUM>', <NUM>", <NUM>'" towards condensing unit <NUM>.

As mentioned, the condensing unit <NUM> is located external to the enclosure <NUM> (or nacelle) and is exposed to natural convective cooling by the wind. In some embodiments, the condensing unit <NUM> may also include a fan outside of the nacelle <NUM> to enhance the heat transfer between the two-phase fluid or gas to the ambient air. Such a system may be useful in cases where the wind speed is insufficient to remove all the heat from the heat generating components present inside the nacelle. The gaseous cooling medium in the condensing unit <NUM> cools down and phase changes back to its liquid state, which is denser than the gaseous state. This liquid cooling medium flows through the second conduit <NUM> towards the distribution manifold <NUM>. The natural forces of convection are the driving force of circulation for the cooling medium. Hot vapor rises up to the condensing unit <NUM>, and cooler liquid flows to the distribution manifold <NUM> via the second conduits <NUM>. Accordingly, the cooling system <NUM> does not require the use of pumps or fans to circulate the cooling medium throughout the system <NUM>, i.e. within the nacelle <NUM>. Hotter components also self-regulate the flow rate of cooling medium passing through the first conduit <NUM>', <NUM>", <NUM> ".

Still referring to <FIG>, the cooling system <NUM> may also include a vapor spreader <NUM> interposed between and fluidly connected to the first conduits <NUM>', <NUM>", <NUM>‴ and the condensing unit <NUM>. In certain embodiments, the vapor spreader <NUM> may be a diffuser that enables the gaseous cooling medium to expand and efficiently fill the condensing unit <NUM>. Further, in an embodiment, the vapor spreader <NUM> may also reduce the pressure of the vapor and reduce its condensing temperature. Moreover, the vapor spreader <NUM> may be housed within the enclosure <NUM>, housed partly within and external to the enclosure <NUM>, or entirely external to the enclosure. In another embodiment, the vapor spreader <NUM> may be attached to the enclosure/nacelle <NUM> (as shown in <FIG>) or the condensing unit <NUM> may be attached to the enclosure/nacelle <NUM>.

The two-phase cooling medium described herein may have a boiling point of about <NUM>° C or lower at typical operating pressures of, as a non-limiting example, about <NUM> bar or lower. Further, the temperature range of the boiling point may be chosen to sufficiently cool electronic components (e.g., transformers, converters, etc.), and prevent them from overheating. Coolants with higher boiling points (e.g., water with a boiling point of <NUM>° C. ) get too hot before they phase change to a gas and result in over-temperature situations for electronic components. Therefore, examples of satisfactory cooling mediums may include dodecafluoro-<NUM>-methylpentan-<NUM>-one (e.g., <NUM>™ Novec™ <NUM>, trademarks of <NUM>), Novec™ <NUM>, R245fa, R1233zd(e), or a fluid with a chemical composition of CF3CF2C(O)CF(CF3)<NUM>. Other less environmentally friendly alternatives could be <NUM>,<NUM>,<NUM>,<NUM>-tetrafluoroethane, R-134a, <NUM>,<NUM>,<NUM>,<NUM>-Tetrafluoropropene, or HFO-1234yf, however, these may not exist in a liquid state for the desired time period or in the desired temperature range.

Referring now to <FIG>, a schematic view of another embodiment of a cooling system <NUM> according to the present disclosure is illustrated. As shown, the condensing unit <NUM> is attached to the enclosure or nacelle <NUM> and the vapor spreader (as shown in <FIG>) is omitted. Further, as shown, the first conduits <NUM>', <NUM>", <NUM>‴ fluidly connect directly to the condensing unit <NUM>. An advantage of this embodiment (and the embodiment shown in <FIG>) is that the nacelle <NUM> may be sealed. External vents allowing air into the nacelle <NUM> are not required, which may be an advantage in sandy, dusty or salt-water environments. Moreover, a sealed nacelle may reduce or eliminate contaminants from entering the interior of the nacelle, and this is advantageous to the various components (i.e., the generator rotor, the generator stator, transformer, converter, etc.) housed therein. Another advantage to the cooling systems <NUM>, <NUM> described herein may be that the condensing unit <NUM> need only be higher than the upper portion of first conduits <NUM>', <NUM>", <NUM>‴ to enable natural convective flow. This enables the condensing unit <NUM> to be attached directly to the top of the nacelle <NUM>. In other words, large or substantial height differentials between the condensing unit <NUM> and the heat-generating components <NUM>-<NUM> are not required for the system to function properly. It can be very problematic to permanently elevate (e.g., on top of a pole) the condensing unit <NUM> due to the substantial wind loads sustained at elevations above the nacelle <NUM>. Therefore, the condensing unit <NUM> is more stable, secure and reliable when attached either directly to the nacelle or to the nacelle via vapor spreader <NUM>. Further, orienting the condensing unit <NUM> normal to the wind flow removes the need for an electric fan. When the wind is blowing at a reduced rate, the associated heat load to dissipate will also be reduced.

Referring now to <FIG>, a schematic view of the first conduit <NUM>'" and a heat exchanger <NUM> thermally connected to heat-generating component <NUM> according to the present disclosure is illustrated. As shown, the heat exchanger <NUM> may be a loop or spiral of first conduit <NUM>'" in thermal connection with component <NUM>, or the heat exchanger may include separate cooling loop that circulate heat transfer mediums. For example, heat exchanger <NUM> may include a heat transfer loop <NUM> that passes in or around the component <NUM>. The loop <NUM> may be configured in a counter-flow arrangement (as shown) with respect to first conduit <NUM>‴, or a cross flow arrangement where heat transfer medium in loop <NUM> travels generally orthogonal to flow in first conduit <NUM>'". The loop <NUM> and conduit <NUM>'" may also be configured in a parallel-flow arrangement, where both flows travel in the same direction. The heat transfer medium in loop <NUM> may be air or fluid, which could exchange heat with flow through the first conduits <NUM>', <NUM>", <NUM>‴ using a parallel plate heat exchanger where the fluid loop <NUM> and the fluid in the first conduits <NUM>', <NUM>", <NUM>‴ flow through alternating passages in parallel direction or opposed to each other. Other types of heat exchangers may also include, but are not limited to, crossflow heat exchangers. Heat transfer from component <NUM> to heat exchanger <NUM> may also occur through a radiative or conductive effect. For example, a highly heat conductive material (e.g., copper or aluminum) can be attached to the component <NUM> and the first conduits <NUM>', <NUM>", <NUM>"' may be embedded within or attached to the highly heat conductive material. The highly conductive material connected to the component <NUM> may also have internal flow conduits or channels that are fluidly connected to the first conduit <NUM> at the inlet and exit. The internal flow conduits or channels may have extended surfaces to increase surface area that enhance the heat transfer from the heat generating component to the fluid. Additional heat exchangers <NUM> (and respective first conduits) may be thermally attached to each heat generating component desired to be cooled.

Referring now to <FIG>, a schematic view of still another embodiment of a passive cooling system <NUM> according to the present disclosure is illustrated. As shown, the passive cooling system <NUM> includes one or more heat exchangers <NUM> associated with one or more heat-generating components located within an enclosure <NUM>, such as, for example, the nacelle <NUM> of the wind turbine <NUM>. For example, as described herein, in an embodiment, the heat-generating component(s) may include the generator <NUM> (e.g. the generator rotor or the generator stator), the gearbox <NUM>, the transformer <NUM>, the converter <NUM> of the wind turbine <NUM>, or any combinations thereof.

Further, as shown, the cooling system <NUM> includes a distribution manifold <NUM> located below the heat exchangers <NUM> and a condensing unit <NUM> located external to the enclosure <NUM> and above the heat exchangers <NUM>. Moreover, as shown, the cooling system <NUM> includes a first conduit <NUM> fluidly connected to each of the heat exchangers <NUM>. In addition, as shown, the first conduits <NUM> are fluidly connected to the distribution manifold <NUM> and the condensing unit <NUM>. For example, as shown, the cooling system <NUM> may include a plurality of first conduits <NUM> connected in parallel between the distribution manifold <NUM> and the condensing unit <NUM>. In such embodiments, as shown, each of the plurality of first conduits <NUM> may be fluidly connected with one of the plurality of heat exchangers <NUM>. In another embodiment, the cooling system <NUM> may include two or more heat exchangers <NUM> connected in series along one of the first conduits <NUM>.

Still referring to <FIG>, the cooling system <NUM> also includes a second conduit <NUM> fluidly connected to the condensing unit <NUM> and the distribution manifold <NUM>. Further, as shown, the cooling system <NUM> includes at least one liquid bridge <NUM> fluidly connected to each of the first conduits <NUM> and the second conduits <NUM> or the distribution manifold <NUM>. More specifically, as shown, the cooling system <NUM> may include a plurality of the liquid bridges <NUM> fluidly connected to the plurality of first conduits <NUM> and the second conduit <NUM> or the distribution manifold <NUM>. In particular embodiments, as shown, one of the plurality of liquid bridges <NUM> may be fluidly connected to each of the plurality of first conduits <NUM> and the second conduit <NUM> or the distribution manifold <NUM>. Accordingly, a two-phase cooling medium (e.g. vapor to liquid) can be circulated through a loop defined by the heat exchangers <NUM>, the first conduits <NUM>, the liquid bridges <NUM>, the condensing unit <NUM>, the second conduit <NUM>, and the distribution manifold <NUM>. As such, the liquid bridges <NUM> transfer the cooling medium in a liquid state from the first conduits <NUM> to the second conduit <NUM> or the distribution manifold <NUM>.

More particularly, as shown in <FIG>, a detailed, schematic diagram of a portion of the multisiphon cooling system <NUM> is illustrated, particularly depicting an embodiment of the liquid bridge <NUM>. In the illustrated embodiment, as example, the liquid bridge <NUM> provides a fluid connection between the rising liquid-vapor column (i.e. first conduit(s) <NUM>) from one of the heat exchangers <NUM> and the descending liquid condensate column (i.e. the second conduit <NUM> or the distribution manifold <NUM>). More specifically, as shown, the first conduit(s) <NUM> may include a splitter <NUM> for capturing the liquid. For example, in certain embodiments, the splitter <NUM> may be a cyclonic splitter or a chevron demister. Similarly, the second conduit <NUM> or the distribution manifold <NUM> may include a mixer <NUM> for receiving the captured liquid and mixing said liquid with the descending liquid condensate. As such, the liquid bridge(s) <NUM> described herein serve to separate liquid from the rising liquid-vapor mixture and return said liquid to the inlet side of the cooling system <NUM>. The liquid bridge(s) <NUM> described herein also lower pressure drop in the system <NUM> by providing parallel pathways for the fluid.

Referring now to <FIG>, a schematic diagram of another embodiment of the cooling system <NUM> is illustrated. As shown, the heat-generator component of the cooling system <NUM> may be the stator <NUM> of the generator <NUM>. More particularly, as shown, the stator <NUM> includes a thermosiphon jacket <NUM> that wraps over the outer diameter of the stator. Further, as shown, the jacket <NUM> may also include one or more channels <NUM> extending from the bottom to the top of the stator <NUM> along the outer circumference thereof. More specifically, as shown, the channels are parallel and may be connected at the top and bottom by inlet and outlet manifolds <NUM>, <NUM>. Thus, in such an embodiment, heat from the stator <NUM> causes the liquid in the jacket <NUM> to be converted to vapor. Moreover, as shown, the vapor rises up passively to the top of the stator <NUM> and collects at the manifold <NUM>. The collected vapor rises further up passively due to buoyancy and thermal contacts with cooler air at the condensing unit <NUM>. The vapor condenses back to liquid form, which is then returned back to the inlet manifold <NUM> to continue the cycle. Though not illustrated in <FIG>, the cooling system <NUM> may also include a liquid bridge as described herein, which serves to separate the liquid from vapor at the outlet manifold <NUM> and return the liquid back to the inlet manifold <NUM>, thereby, by passing the condenser. This provision reduces system pressure drop to improve the thermosiphon mass flow rate and hence the thermal performance of system.

Referring now to <FIG>, various embodiments of the liquid bridge <NUM> of the passive cooling system <NUM> described herein is illustrated. In particular, as shown in <FIG>, the liquid bridge(s) <NUM> described herein may be a tubular member <NUM> inclined at an angle (e.g. ranging from <NUM> to <NUM> degrees) between the first conduits <NUM> and the second conduit <NUM> or the distribution manifold <NUM>. In another embodiment, as shown in <FIG>, the liquid bridge(s) <NUM> described herein may also include one or more traps <NUM>, such as a P-trap or running trap, to improve liquid-vapor separation. Thus, in such embodiments, such trap(s) <NUM> are configured to discourage the flow of vapor through the liquid bridge.

Claim 1:
A passive cooling system (<NUM>, <NUM>, <NUM>), comprising:
a heat exchanger (<NUM>, <NUM>) thermally connected to a heat-generating component located within an enclosure (<NUM>);
a distribution manifold (<NUM>, <NUM>) located below the heat exchanger (<NUM>, <NUM>);
a condensing unit (<NUM>, <NUM>) located external to the enclosure (<NUM>) and above the heat exchanger (<NUM>, <NUM>);
a first conduit (<NUM>', <NUM>", <NUM>"', <NUM>) fluidly connected to the heat exchanger (<NUM>, <NUM>), the distribution manifold (<NUM>, <NUM>), and the condensing unit (<NUM>, <NUM>);
a second conduit (<NUM>, <NUM>) fluidly connected to the condensing unit (<NUM>, <NUM>) and the distribution manifold (<NUM>, <NUM>);
a liquid bridge (<NUM>) fluidly connected to the first conduit (<NUM>', <NUM>", <NUM>"', <NUM>) and the second conduit (<NUM>, <NUM>) or the distribution manifold (<NUM>, <NUM>); and,
a two-phase cooling medium that circulates through a loop defined by the first conduit (<NUM>', <NUM>", <NUM>‴, <NUM>), the liquid bridge (<NUM>), the condensing unit (<NUM>, <NUM>), the second conduit (<NUM>, <NUM>), the heat exchanger (<NUM>, <NUM>), and the distribution manifold (<NUM>, <NUM>),
wherein the liquid bridge (<NUM>) transfers the cooling medium in a liquid state from the first conduit (<NUM>', <NUM>", <NUM>'", <NUM>) to the second conduit (<NUM>, <NUM>) or the distribution manifold (<NUM>, <NUM>).