GB2566247A - A lighting apparatus - Google Patents

Abstract

A lighting apparatus 12 comprises a first fluid conduit 16 including an accessory port 34, and a lighting fixture 26 engaged with the accessory port 34. The lighting fixture 26 includes a lamp unit and a second fluid conduit 94 configured to transfer heat from the lighting fixture to the first fluid conduit 16 via a heat pipe (84, Fig. 4). The lighting apparatus may be used in a plant growing system.

Description

A Lighting Apparatus

TECHNICAL FIELD

The present disclosure relates to a lighting apparatus which is particularly efficient at dissipating heat generated by light fixtures of that apparatus. Aspects of the invention relate to a heat transfer system for use in a lighting apparatus.

BACKGROUND

Indoor plant growing systems are commonly used to grow plants for food crops such as salad leaves, tomatoes and the like. Known indoor growing systems are generally housed in controlled environments so that they are able to produce crops all year round, regardless of the climate or season. Such systems typically combine an enclosed chamber with artificial lighting, irrigation and air conditioning systems in order to provide tight environmental control. The insulated chambers help to maintain optimum control of plant growth by excluding external influences, such as heat, light, insects and pathogens from the growing environment whilst the lighting and irrigation systems provide the illumination, water and nutrients that the plants need to grow.

Artificial lighting used for indoor growing systems is typically configured to provide a minimum light requirement corresponding to the wavelengths and intensity for growth. For example, salad plants only require a relatively low light intensity whereas flowering plants or fruits require higher light intensities. However, in order to illuminate the plants to a sufficiently high level the lighting systems also radiate a significant amount of thermal energy, which can thereby be absorbed by the plants.

Controlling the temperature and humidity of the growing environment is critical for indoor growing systems. Under sunlit conditions the majority of a plant’s water consumption is used for evaporative cooling (evapotranspiration). In order for the evapotranspiration to occur effectively, the relative humidity of the environment must be controlled. Reducing the humidity also helps to prevent condensation and mould growth.

To address this issue, known systems are often fitted with de-humidification equipment which is arranged to remove the moisture from the air so as to maintain optimal plant growing conditions within the chamber. However, conventional de-humidifying processes are energy intensive and so minimising moisture usage by the plant is important.

Maintaining an elevated temperature within the growing chamber or radiant heat gain to the plants, especially from the luminaire leads to even greater levels of evapotranspiration. In other words, the heat that is emitted from the lighting causes the plants to evaporate more water just to keep cool, which leads to a subsequent increase in humidity inside the growing chamber. This additional water uptake from the plants serves no useful growth function and the increased humidity requires more energy to be removed from the growing environment, with a subsequent increase in the energy consumption of the indoor growing system.

Some known artificial lighting systems use light emitting diode (LED) based lighting fixtures or ‘luminaires’ which comprise a group of LEDs mounted to a common control board and packaged together as a single lighting module. Such devices are attractive for indoor growing environments over other lighting technologies due to their enhanced illumination, efficiency and adaptability to different lighting applications. However, such LED luminaires still tend to convert less than 30% of the electrical-energy they receive into light, with the remaining 70% radiated as heat.

As well as the thermal energy that is emitted into the growing environment by the lighting fixtures, the build-up of heat within the lighting fixture itself is also considered to be a limiting factor for the illumination output of luminaires. In particular, elevated temperatures at the junction between the LEDs and the underlying control board may cause degradation of the active layers of the semiconductor material used in the LEDs, which can lead to a reduction in the operating lifetime of the luminaire. Under normal operating conditions the output of a typical LED lighting system is limited by its ability to maintain the LED luminaire below an operating temperature of about 105°C.

Approaches to addressing this problem have involved fitting luminaires with large metal heat sinks, which are thermally coupled to the LED devices in some way so as to conduct the excess heat away from the luminaire and out into the surrounding environment. For example, some conventional lighting devices are arranged to transfer heat directly into the growing environment. Alternatively, some heat may also be dissipated up into a crawl space above a ceiling of the growing chamber in which the luminaire is installed. However, such heat sinks are large, heavy and costly, which limits their practicality particularly when many luminaires are needed to light a large growing area. Also, the limited effectiveness of the heat sinks to dissipate heat energy imposes an upper limit on the light output of the luminaires due to the need to maintain the temperature of the LED devices at an acceptable level so as to avoid premature failure of those devices.

More recent attempts to improve the operating efficiency of these luminaires have utilised heat pipes, for example as disclosed in US-A1-2009-0225540. While this approach tends to improve the transfer of heat away from the LED device, the effectiveness of heat extraction is once again limited by the heat sink, which can quickly become saturated with thermal energy.

The present invention has been devised to mitigate or overcome at least some of the above-mentioned problems by providing a lighting system that produces illumination of a sufficient intensity, whilst at the same time dissipating the heat generated from the luminaire more effectively in order to produce optimal plant growing conditions.

SUMMARY OF THE INVENTION

According to an aspect of the present invention there is provided a lighting apparatus comprising: a first fluid conduit, including an accessory port, and a lighting fixture engaged with the accessory port of the conduit; wherein the lighting fixture includes a lamp unit, and a second fluid conduit configured to transfer heat from the lighting fixture to the first fluid conduit

According to the above described apparatus, thermal energy that is produced by the lighting fixture is first extracted using the second fluid conduit, which then transfers the thermal energy to the first fluid conduit whereby it is then transported further away from the lighting fixture, into the external environment. Advantageously, this arrangement is a very efficient way to transfer thermal energy from the lighting fixture and, moreover, avoids the need to attach large and heavy heat sinks to the light fixture. The thermal energy (or heat) from the lighting fixture is rapidly extracted and transported to the external environment, which is substantially displaced from the lighting fixture, unlike with conventional heat sinks which can only dissipate heat into the environment in the immediate vicinity of the lighting fixture. Thus, the above described lighting apparatus is able to dissipate thermal energy away from the plant growing environment where it would otherwise have a negative impact on the growing conditions of the plants housed therein.

The lamp unit may comprise at least one light emitting diode (LED). The emission from LED light devices is highly configurable thereby allowing the lighting apparatus to be optimised and controlled so as to match the growing conditions of a variety of plant species. Such LED lamp units may also be adjusted over time to suit the changing growing requirements of a particular plant species throughout its life cycle.

The lamp unit may be a surface mounted LED (SMD-LED) device. Advantageously, SMD-LED type devices exhibit a very low electrical power consumption whilst being able to emit light that is highly suited to the growing conditions of a number of plant species. Alternatively, the lamp unit may be a chip-on-board LED (COB-LED) device, which emits light with a high illumination intensity.

The second fluid conduit may be arranged to dissipate thermal energy from the lamp unit. Advantageously, thermal energy from the lamp unit may be absorbed by thermal transfer fluid which is housed within the second fluid conduit. The thermal fluid transfers the absorbed thermal energy directly to the first fluid conduit where it is absorbed by the thermal transfer fluid housed therein. Therefore, any excess heat that is emitted by the lamp unit can be quickly and continuously extracted from the lamp unit.

The second fluid conduit may be arranged in direct thermal contact with the lamp unit. This conveniently ensures that the heat emitted from the lamp unit is quickly transferred to the second fluid conduit, and thereby absorbed by the thermal transfer fluid housed therein. The second fluid conduit may be mounted to a back of an illuminating surface of the lamp unit so that thermal energy may be conducted directly to the second fluid conduit.

The second fluid conduit may be a heat-pipe. The thermal transfer fluid that is sealed within the heat-pipe is configured to rapidly transfer thermal energy from one end of the pipe to another through a cyclical evaporation and condensation process. Advantageously, the heat-pipe is able to transfer thermal energy from the lamp unit to first fluid conduit without the need for active circulation of the heat transfer fluid contained within the second fluid conduit.

The second fluid conduit may comprise a plurality of heat-pipes. By combining the thermal extraction capacity of the plurality of heat-pipes, the second fluid conduit is able to transfer more thermal energy from lamp unit to the first fluid conduit.

The second fluid conduit may be configured to protrude through the accessory port and extend into the interior of the first fluid conduit such that, in use, thermal energy from the lighting fixture is transferred directly to the fluid flow contained within the first fluid conduit. Thermal energy from the lighting fixture can be advantageously extracted quickly from the second fluid conduit by the fluid flow contained within the first fluid conduit.

The second fluid conduit may comprise a connector configured to removably engage with the accessory port of the first fluid conduit. The connector enables the first and second fluid conduits to be conveniently engaged with each other such that the first fluid conduit physically supports the weight of the second fluid conduit. The connector also provides at least partial support to the lighting fixture which may be attached to the opposite end of the second fluid conduit.

The connector may be configured to seal the second fluid connector within the accessory port such that, in use, the fluid flow is prevented from leaking out of the first fluid conduit. Advantageously, the connector enables the first and second fluid conduits to be conveniently engaged with each other to form a water tight seal where they meet. The connector may comprise a snap-fit connector or a screw thread configuration.

The first fluid conduit may include more than one accessory port carrying a lighting fixture. The first fluid conduit may accommodate any number of lighting fixtures depending on the requirements of the lighting apparatus. Advantageously, a single fluid conduit is configurable to simultaneously extract heat from a plurality of lighting fixtures.

The first fluid conduit may have an elongate tubular structure. The first fluid conduit may comprise a plurality of conduit elements. The first fluid conduit may comprise a connector provided between a pair of neighbouring conduit elements, the connector being configured to provide a fluid connection between those two conduit elements. Advantageously, any number of conduit elements may be combined in a modular fashion to form a conduit-string through which thermal transfer fluid can flow in order to transfer thermal energy away from the at least one lighting fixture. The first fluid conduit may be expanded to accommodate the requirements of a variety of different growing environments.

The first fluid conduit may incorporate a power supply conductor configured to supply power to the lighting fixture. The power supply conductor may be mounted to an external surface of the first fluid conduit. The power supply conductor may be a conductor which is received within a channel that is provided along an external surface of the first fluid conduit. Advantageously, a single power supply conductor may be configured to supply power to each lighting fixture of the lighting apparatus. The conductor may be formed in the shape of a strip, which lends itself to being coupled to the conduit string, for example in a continuous arrangement. The conductor may also be in the shape of a wire in other embodiments.

The lighting fixture may comprise a fixing clamp for removably fixing the lighting fixture to the first fluid conduit. The fixing clamp thereby, at least partially provides physical support for the lighting fixture.

The fixing clamp may comprise an electrical connector configured to provide an electrical connection between the power supply conductor and the lighting fixture when the fixing clamp is engaged with the first fluid conduit.

The fixing clamp may be configured to overlay the power supply conductor and engage with a securing ridge that is provided on an external surface of the first fluid conduit, wherein the electrical connector may be provided on a conduit facing surface of the overlying fixing clamp such that it forms an electrical contact with the power supply conductor when the fixing clamp is engaged with the first fluid conduit. The fixing clamp may therefore be provided to both secure the lighting fixture to the first fluid conduit whilst simultaneously supplying power to the lighting fixture.

The first fluid conduit may comprise an end cap configured to seal an exposed end of the first fluid conduit. The power supply conductor may be received through a hole in the end cap.

The first fluid conduit may be provided with an input port and an output port configured, in use, to connect the first fluid conduit to an external pumping assembly for circulating fluid therethrough. The first fluid conduit may be formed from an engineering polymer. Alternatively, the first fluid conduit may be formed from an aluminium alloy.

According to a further aspect of the present invention there is provided a heat transfer system for use in a lighting apparatus, the heat transfer system comprising a first fluid conduit that defines an accessory port, and an accessory fixture engaged with the accessory port of the conduit; wherein the accessory fixture includes a heat generating component and a heat pipe configured to transfer thermal energy from the heat generating component to the first fluid conduit. The accessory fixture may be a lighting fixture.

The heat transfer system may further comprise a pumping assembly configured to circulate fluid through the first fluid conduit. The fluid may be circulated through the heat transfer system in order to advantageously extract thermal energy from the accessory fixtures.

The heat transfer system may further comprise a temperature control assembly configured to adjust the temperature of the fluid circulated through the first fluid conduit. By altering the temperature of the fluid, the temperature control assembly is able to control the amount of thermal energy that is extracted from the accessory fixture.

The heat transfer system may further comprise a controller configured to control an operating parameter of the heat transfer system in dependence on receiving an input control signal. Hence, the temperature of the fluid may be advantageously controlled in response to a change in the operation of the accessory fixture.

The input control signal may be a measured parameter of the growing system. The output of the accessory fixture may be adjusted in response to a requirement of the growing environment. The measured parameter may be a temperature value and/or a flow rate value of the fluid circulated through the first fluid conduit.

According to a further aspect of the present invention there is provided a plant growing system comprising a heat transfer system for use in a lighting apparatus, the heat transfer system comprising a first fluid conduit that defines an accessory port, and an accessory fixture engaged with the accessory port of the conduit; wherein the accessory fixture includes a heat generating component and a heat pipe configured to transfer thermal energy from the heat generating component to the first fluid conduit.

According to a still further aspect of the present invention there is provided a modular lighting apparatus comprising: at least one lighting fixture; and, a plurality of fluid conduit elements each configured to connect to a neighbouring conduit element to form a conduit-string which defines a fluid conduit of the modular lighting apparatus; wherein at least one of the conduit elements comprises an accessory port configured to engage with the lighting fixture.

At least two of the conduit elements may include an accessory port carrying a lighting fixture. Each of the at least two conduit elements may include more than one accessory port carrying a lighting fixture.

According to a yet further aspect of the present invention there is provided a fluid conduit element for use in the modular lighting apparatus described above, the fluid conduit element may comprise: an accessory port configured to engage with an accessory fixture, and, a power supply conductor fixture configured to house a power supply conductor; wherein the conduit element is configured to electrically connect the accessory fixture to the power supply conductor when the accessory fixture is engaged with the accessory port.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more readily understood, reference will now be made, by way of example only, to the accompanying drawings, in which:

Figure 1 provides a representative view of a plant growing system including a lighting apparatus according to an embodiment of the invention;

Figure 2 is a perspective view of a lighting apparatus according to an embodiment of the invention;

Figure 3 is an end view of the lighting apparatus of Figure 2;

Figure 4 is an exploded view of the lighting apparatus of Figure 2;

Figure 5 is a longitudinal-section of the lighting apparatus of Figure 2, showing a lighting fixture of the lighting apparatus engaged with an accessory port of the conduit according to an embodiment of the invention;

Figure 6 is an enlarged cross-section of the lighting apparatus of Figure 2 according to an embodiment of the invention;

Figure 7 is a perspective view of a lamp unit of the lighting apparatus according to an embodiment of the invention;

Figure 8 is a perspective view of a heat pipe of the lighting apparatus according to an embodiment of the invention;

Figures 9 is a perspective view of a lighting apparatus according to an embodiment of the invention; and

Figure 10 is a top-down view of the lighting apparatus of Figure 9 according to an embodiment of the invention.

DETAILED DESCRIPTION

A specific embodiment of the invention will now be described in which numerous specific features will be discussed in detail in order to provide a thorough understanding of the inventive concept as defined in the claims. However, it will be apparent to the skilled person that the invention may be put into effect without these specific details and that, in some instances, well known methods, techniques and structures have not been described in detail in order not to obscure the invention unnecessarily.

To place the embodiments of the invention in a suitable context, reference will firstly be made to Figure 1, which illustrates a perspective view of a plant growing system 10 including a lighting apparatus 12 that is suspended above a pair of growing planters

14. Note that although only a single parallel pair of growing planters 14 is shown here for convenience, the lighting apparatus 12 may be configured to provide illumination for any number of growing planters 14 arranged in any configuration.

The growing system 10 is housed in an insulated growing chamber (not shown, but its presence is implied) in order to isolate the growing planter 14 from the external environment. Such growing chambers are typically insulated in order to maintain the temperature of the growing chamber at a level that optimises plant growth. The growing chamber may also be provided with a door, or window opening, in order to allow access to the plants within the growing planters 14. It is envisaged that the 10 growing system 10 may be configured so that it can be housed in an alternative type of suitable enclosure including, for example, a glasshouse, a greenhouse or a polytunnel.

Since the growing system may be sealed off from the external environment, the growing chamber may be furnished with a series of connecting ports for connecting to an irrigation system (not shown) which is arranged to provide water to the planters through a hose or piping arrangement. An electrical power supply is also supplied to the lighting apparatus through an associated cable assembly.

The lighting apparatus 12 comprises a luminaire support assembly 13, which is suspended above the growing planters 14 by a series of support cables 18. The support assembly 13 is shown in Figure 1 following a generally rectangular configuration such that it substantially overhangs the growing planters 14 which are oriented in parallel. Alternatively, the support assembly 13 may be arranged to follow a linear configuration so that it overhangs a single row of linearly arranged growing planters. However, it is envisaged that the support assembly 13 may be arranged in any suitable configuration in order to match the arrangement of the growing planters

14. For example, it is envisaged that the lighting apparatus 12 may be configured to be accommodated within a multi-tiered growing planter, in which each tier of growing planters is provided with a corresponding section of the support assembly 13.

Each of the support cables 18 is connected at one end to an upper surface 22 of the support assembly via a hanger attachment 46, and at another end to the ceiling of the growing chamber. Alternatively, the lighting apparatus 12 may be supported using an integrated rigid scaffold structure such as that which is commonly known in the art.

A principle role of the support assembly is to provide support for numerous lighting fixtures 26 that are suspended from an underside surface 24 of the supporting assembly. However, addition to supporting the lighting fixtures 26, the support assembly 13 further provides a means to manage the thermal energy generated by those fixtures. To this end, the support assembly 13 comprises a hollow conduit through which fluid can flow in order to dissipate heat from the lighting fixtures 26 to the external environment. The support assembly 13 is fluidly connected to a fluid supply system that is configured to supply fluid to, and retrieve fluid from, the conduit.

Conveniently, the support assembly 13 also includes a power supply assembly which is arranged to provide power to the lighting fixtures 26.

As has been mentioned above, the support assembly 13 is shaped, in this embodiment, generally to match the arrangement of the growing planters 14. Although the support assembly 13 could be formed of a single piece conduit shaped specifically to match a particular arrangement of growing planters, conveniently in this embodiment the support assembly 13 is formed from a number of elongate conduit elements 16a to 16d, which are coupled together in order to form a single conduitstring 16. The conduit elements may be extruded from an aluminium alloy. Alternatively, the conduit elements may be formed from an engineering polymer. Each of the individual conduit elements are coupled to suitable connectors, as will be described, so the support assembly can be assembled with any desired shape, and it will be appreciated that this modularity enables the support assembly 13 great flexibility in providing the optimum lighting configuration for a given growing environment.

Owing to the rectangular formation of the conduit-string 16, a right-angled conduit element 17 is provided at the junction between elements 16b/16d, 16d/16a and 16a/16c, respectively. Each of the conduit elements is configured so as to enable any number of elements to be arranged end-to-end in order to form a conduit-string 16 with a variety of different lengths and conformations. Each of the hollow conduit elements is a rigid tubular extrusion comprising an interior channel. Thus, when a plurality of conduit elements are coupled together to form a single conduit-string 16, a continuous interior channel is formed within the conduit-string 16, which allows fluid to flow from one extreme end of the conduit-string 16 to another. In this way, the conduit-string 16 defines a first fluid conduit of the lighting apparatus 12.

The conduit elements may take any number of different shapes or forms including, for example, a T-shaped element, which may be used to split the flow of fluid between two or more branches of the conduit-string 16.

The lighting fixtures 26 are spaced out along particular elements of the support assembly 13 such that they are suspended above the growing planters 14. Each lighting fixture 26 is rigidly suspended from the underside of the support assembly 13 and thereby arranged to emit light down onto the planters 14 below. Each of the plurality of light fixtures 26 are also thermally coupled to the channel that is formed within the interior of the conduit-string 16 such that any heat that is generated by the light fixtures 26 can be transmitted to the fluid passing along the channel of the conduit-string 16.

Each lighting fixture 26 is electrically connected a power supply conductor in the form of two power leads 40, which are arranged along the side walls of the conduit-string

16. Each of the power leads 40 are connected to a power supply unit 42 via an external power cable 44. The power cable 44 is electrically connected to both power leads 40 through a detachable power supply coupling, or connector 49, which straddles the underside of the conduit-string 16 so as to form a decouple-able connection with the power leads 40. Advantageously, the power leads 40 run along each of the conduit elements 16a, 16b, 16c, 16d thereby forming a continuous power connection along the length of the conduit-string 16. Put another way, the connector 49 can be engaged with the conduit-string 16 at any point along its length and still form an electrical connection with power leads 40. This reduces the need to connect each element of the conduit-string 16 to a separate power supply. For example, a single power connector 49 can be used to supply power to the entire lighting apparatus 12 regardless of the way in which the conduit elements are arranged or configured.

Remaining with Figure 1, a conduit connector 39 is provided at the junctions between the conduit elements. Each of the conduit connectors 39 is configured to enable fluid to flow from one conduit element to its adjoining neighbour. Furthermore, the conduit connectors 39 allow for an electrical connection to be maintained across the junction between adjoining conduit elements of the conduit-string 16. An end cap 38 is provided at each exposed end of the conduit-string 16. Each end cap 38 is configured to seal off the end of the conduit-string 16 so as to define a start or end of the fluid channel housed therein. Hence, an end cap 38 is provided at the exposed end of element 16c, where it meets the side of element 16b, so as to seal off the start of the conduit-string 16. A further end cap 38 is provided at the exposed end of conduit element 16d in order to seal off the end of the conduit-string 16.

An input fluid supply hose 28 is provided to fluidly connect an inlet port 34 located on element 16c of the conduit-string 16 to a fluid-flow control unit 30 of the system 10. As will be described, the fluid-flow control unit 30 serves to control and regulate various characteristics of the fluid flow through the conduit string. For example, the control unit30 may be equipped with appropriate control and pumping functionality to start and stop fluid flow under the control of a predefined control program, and also to control the flow between given minimum and maximum flow rates. Suitable functionality may also be included to control the temperature of the fluid that flows through the conduit, although generally it is envisaged that the optimum temperature will be for the fluid to be as cold as possible. With this in mind, an output hose 32 is provided to connect an outlet port 36 located on element 16b of the conduit-string 16 to the fluid control unit 30. The inlet and outlet ports 34, 36 are provided at an underside of elements 16c and 16b of the conduit-string 16, respectively. The inlet and outlet ports 34, 36 may each be provided on an end cap 38, as will be described in more detail below. The inlet and outlet ports 34, 36 may alternatively be provided at an upper side of the conduit-string 16, in order to accommodate any particular packaging requirement of the system. The input hose 28 is arranged to supply fluid to the conduit-string 16 whereas the output hose 32 is arranged to return the fluid to the control unit 30. Thus, the inlet and outlet ports 34, 36 are arranged to allow fluid to pass into and out of the internal channel of the conduit-string 16.

Hence, the inlet and outlet ports 34, 36 are located at opposite and distal ends of the conduit-string 16 such that, in use, a continuous flow of fluid is directed through the internal channel of the conduit-string 16, as described by arrow A in Figure 1, under the control of the fluid-flow control unit 30. The conduit-string 16 therefore forms a discontinuous loop with elements 16c and 16b forming the fluid entry and exit points, respectively.

A valve assembly (not shown) may be provided to isolate an individual component of the conduit-string 16 in order to allow servicing of the apparatus without interrupting the fluid flow to other components of the system 10. The connecting hoses 28, 32 may be flexible so that they can be manipulated to facilitate the servicing of the conduitstring 16 and/or the fluid control unit 30.

The fluid-flow control unit 30 may include a pumping means, which is arranged to circulate fluid into and around the fluid conduit-string 16. The control unit 30 may also include a means for adjusting the temperature of the fluid that is circulated through the conduit. By lowering the temperature of the fluid that is circulating through conduitstring 16 enhances the extraction of thermal energy from the light fixtures 26, thereby enabling them to operate more efficiently.

The control unit 30 may also include a means of controlling the operation of the control unit 30 in dependence on receiving an input control signal and/or a measured parameter of the growing system 10. The input control signal may include a demand by a user of the system 10 to reduce the operating temperature of the lighting fixtures

26. The measured parameter may include a measured temperature value of the growing environment.

The heat transfer fluid that is used in the first fluid conduit may be chosen from any number of suitable solutions. Typically, water is used however, an ethylene-glycol type liquid, which exhibits good dielectric properties and a low temperature boiling point, may also be used.

Referring now also to Figure 2, the modular construction of the conduit-string 16 will now be described in more detail. The separate conduit elements or ‘modules’ are shown connected in series between the outlet and inlet ports 34, 36. It should be appreciated that this type of series connection requires only one inlet and one output hose 28, 32 to connect the conduit-string 16 to the fluid-flow control unit 30. The conduit-string 16 is expandable such that it can accommodate any number of additional conduit elements, which could be connected in parallel, or in series, or in any such combination. Therefore, the conduit-string 16 may be arranged in numerous alternative configurations in order to suit the requirements of a particular growing system 10. For example, the inlet 34 and outlet 36 ports could be arranged at opposite ends of a conduit-string 16 which is provided with multiple branches arranged in parallel with each other. In such a configuration the fluid flow may be split between each of the branches before recombining to be extracted from a common outlet port 36. Alternatively, each of the separate branches may be provided with a separate outlet port 36 to circulate the fluid back to the control unit 30. Furthermore, it is envisaged that more than one lighting apparatus 12 could be connected to a single control unit 30 through separate connecting hoses 28, 32.

During operation of the lighting apparatus 12, the light fixtures 26 generate heat which must be dissipated in order to prevent their illumination performance from degrading over time. Furthermore, the operating efficiency of the light fixtures 26 is increased by reducing their operating temperature. As will be described in more detail, the circulation of fluid through the fluid conduit is configured to extract heat from the light fixtures 26 such that they can operate at higher outputs for longer periods of time.

In particular embodiments where the lighting source is provided by an SMD-LED, approximately 80% of the electrical energy that is inputted to the lighting fixture 26 is extracted by the conduit-string 16 of the lighting apparatus 12. The heat that is extracted from the lighting fixture 26 would otherwise be emitted as infrared radiation or transferred to the other components of the lighting fixture 26 through conduction. The remaining 20% of the inputted electrical energy is typically emitted to the surrounding environment as heat and light. In embodiments where the lighting source is provided by a COB-LED, approximately 70% of the electrical energy is inputted to the lighting fixture 26 is extracted by the conduit-string 16 of the lighting apparatus 12 and 30% is emitted to the surrounding environment.

The fluid control unit 30 is able to pump fluid through the input hose 28, into the internal channel of the conduit-string 16 and then out through the output hose 32 connected thereto. Advantageously, this allows for the heavy cooling equipment such as heat exchangers to be located away from the individual light fixtures 26, and preferably outside of the growing chamber. Thus, the control unit 30 is able to manage the thermal energy generated by the light fixtures much more effectively since the cooling fluid carries thermal energy away from the light fixtures much more efficiently than would be the case with conventional heat sinks which provide only passive cooling in an ambient airflow. Moreover, the support assembly only requires sufficient structural support to accommodate the weight of the individual components of the lighting apparatus 12 and the fluid that can be circulated within it, whereas substantial mass of a conventional heat sink assembly, when directly mounted to a light fixture, must be supported at an elevated position.

Whereas Figure 1 shows an outline of the overall apparatus, Figures 2 and 3 show a more detailed view of the components of the lighting apparatus 12. In particular, Figures 2 and 3 illustrate how a lighting fixture 26 is engaged with a single conduit element of the conduit-string 16. As explained previously, the conduit element has an extruded tubular construction defined by a rectangular cross section consisting of an upper wall, a lower wall and two opposing side-walls.

Figure 2 illustrates three fitments or accessories attached to the conduit element 16a: the hanger attachment 46, the lighting fixture 26 and the power supply connector 49. The hanger attachment 46 provides a physical coupling between the support cable 18 and the conduit-string 16 by virtue of two supporting arms 50 that extend down the sidewalls of the conduit-string 16. A hook is provided on an inward facing surface of each arm 50 so that they can co-operate with a first securing ridge 52 that is provided on either side of the conduit-string 16. Both securing ridges 52 extend along the length of the conduit-string 16 such that the hanger attachment 46 can be located at any position along its length.

The connector 49 straddles the underside of the conduit-string 16. A securing hook is provided on an inward facing surface of mutually-opposed arms 51 to enable the connector 49 to engage with a second securing ridge 68, which is disposed on either side of the conduit 26. An electrical connector (not shown) is arranged on an inward facing surface of the arms 51 such that it overlies the power leads 40 when the connector 49 is engaged with the conduit-string 16. Thus, the connector forms a detachable power connection between the power leads 40 and the external power cable 44.lt is envisaged that the functionalities of the hanger attachment 46 and the power connector 49 may be combined into a single unit.

A further accessory is provided for the conduit-assembly 16 in the form of a power lead cover (not shown). The cover comprises of a number of extruded planar panels, each of which is provided with a clip-on connecting means for securing each panel to the side of the conduit-string 16 such that it overlies the exposed power leads 40 located thereon. The clip-on connecting means comprises a hook, arranged along an upper edge of the cover, which is configured to engage with the second securing ridge 68 of the conduit-string 16 in a similar fashion to the arms 51 of the power connector 49, such that the cover is held in place over the power leads 40.

With particular reference to Figure 4, the power leads 40 comprise wires or rods, having a circular cross section. A supportive channel 41 is provided on each side wall of the conduit-string 16 to house the power leads 40 when they are installed on the conduit-string 16. As an alternative to the wires or rods, the power leads may comprise conducting ribbons or strips, which may be more readily packaged within the conduitstring 16, whilst still providing a high current electrical connection to the light fixtures 26. The supportive channels 41, which accommodate the connecting strips, may be easier to form during the manufacturing of the conduit-string 16. The conducting leads 40 may be made from brass, copper, or alternatively from any other suitable conductive material.

With reference to Figures 2 to 5, the end cap 38 is provided with either an inlet or an outlet port 34, 36, which are configured to be connected, respectively, to an input or an output hose 28, 32. In this way the end caps 38 enable fluid to be directed through the conduit-string 16 from one end to another. An inner portion 43 of the cap 38 may be provided with a sealing means in the form of a series of rubber o-rings (not shown), which are configured to form a watertight seal with an interior surface of the walls of the conduit-string 16 when the inner portion 43 is inserted into the open end of the conduit-string 16. Alternatively, the inner portion 43 may be bonded to the interior of the conduit-string 16 by a water resistant bonding agent, or any other suitable bonding means. It is envisaged that when the end cap 38 is not provided with either an inlet or an outlet port 34, 36, it thereby forms a barrier at the exposed end of the conduit-string

16.

The end cap 38 also has a second function, in this embodiment, in that an outer portion of the end cap 38 is provided with a pair of guiding holes 41, which are arranged to receive the power leads 40 when the end cap 38 is fixed to the end of the conduit-string 16. Therefore, the end cap 38 may be configured to maintain an electrical connection between two adjoining conduit elements whilst simultaneously inhibiting the flow of fluid across the junction between those conduit elements.

Turning now to the third accessory, the lighting fixture 26, from Figure 4 particularly it can be seen that the lighting fixture 26 comprises a protective housing 56 which houses a luminaire 54, or lamp unit. The lighting fixture 26 also houses control electronics 55 for operating the luminaire 54 when the lighting apparatus 12 is in use. The housing 56 is fixedly attached to the conduit-string 16 by means of a securing fastener, or fixing clamp 66. The fixing clamp 66 is configured to straddle the underside of the conduit-string 16 and comprises mutually-opposed grip portions in the form of elongate arms 72 for this purpose. A securing hook is provided on an inward facing surface of each arm 72 to enable the clamp 66 to engage with the second securing ridge 68 disposed on either side of the conduit 26. The second securing ridges 68 run along the length of the conduit-string 16 and are located at a position on the side wall of the conduit-string 16, which is located lower than the first securing ridge 52 but higher than the power leads 40. Thus, the clamp 66 does not interfere with the hanger attachment 46, which itself is arranged to attach the conduit-string 16 to the supporting cable 18.

In more detail, the housing 56 comprises an upper portion 58 and a lower portion 60, which are held together by suitable fasteners such as screws 62. Other fastening means would also be acceptable such as a snap-fit fastener or a suitable bonding agent. The screws 62 are configured to engage with screw holes arranged at the four corners of the upper and lower housing portions 58, 60 in order to secure the housing 56 together. A rubber seal 64 is provided at the perimeter edge of the upper and lower housing portions 58, 60. The rubber seal 64, thereby forms an environmental seal between the upper and lower housing portions 58, 60 when the housing 56 is assembled.

The fixing clamp 66 is fixedly attached to the housing 56 by means of a pair of rigid tabs 69 extending downwards from a base of the clamp. The tabs 69 are received within respective openings 70 on an upper surface of the upper housing portion 58. Each tab 69 is provided with a catch that is configured to secure each tab 69 within its corresponding opening 70, when the fastener 66 is engaged with the housing 56.

Reference will now be made also to Figures 5 and 6, which shows the lighting fixture 26 engaged with an accessory port 92 of the conduit-string 16, and from which the internal details of the lighting fixture 26 and the relative spacing between its components are more readily apparent. The housing 56 of the lighting fixture 26 is further divided transversely by an internal bulkhead 73, or wall, into a luminaire compartment 74 and an electronics compartment 76. The luminaire compartment 74 is arranged to house the luminaire 54 whilst the electronics compartment 76 houses the control electronics 55, whilst the bulkhead 73 protects the control electronics 55 from the thermal output of the luminaire 54. Alternatively, the luminaire and electronics compartments 74, 76 may be housed in separate modules. According to this configuration, the separate compartments may comprise independent means of engaging with the conduit-string 16.

A region of the lower housing portion 60 which covers the luminaire compartment 74 is transparent such that it defines a lens 64 of lighting fixture 26. The lens 64 is arranged directly below the luminaire 54 and is configured to allow light emitted from the luminaire 54 to radiate out from the lighting fixture 26 onto the growing planters 14 below.

The control electronics 55 are shown in Figures 4 and 5 as a printed circuit board (PCB), which is connected to the power leads 40 via an electrical connector assembly 78. A first connector portion 78a of the connector assembly 78 is arranged within the housing 56 of the lighting fixture 26. A second connector portion 78b is arranged on an inward facing surface of the elongated arms 72 such that it overlies the power leads 40 when the clamp 66 is engaged with the conduit-string 16. The clamp 66 is, therefore, configured to simultaneously overlay the power leads 40 and engage with the securing ridge 68 that is provided on an external surface of the first fluid conduit. In this way, the electrical connector assembly 78 is integrated into the clamp 66 in order to establish an electrical connection between the lighting fixture 26 and the power leads 40 when the fastener 66 is engaged with the conduit-string 16.

The first connector portion 78a is provided with a socket 79 such that it is suitably configured to engage with the second connector portion 78b when the tabs 69 of the fastener 66 are inserted into the upper housing portion 58 of the lighting fixture 26. In this way, the first and second connector portions 78a, 78b form a continuous yet decouple-able connection between the power leads 40 and the PCB. The PCB is further connected to the luminaire 54 by a PCB connector 80, which is arranged to pass from the electronics compartment 76 into the luminaire compartment 74 of the housing 56 through the bulkhead 73. Thus, the PCB forms an electrical bridge between the power leads 40 and the luminaire 54 such that it can direct power to the luminaire 54 during operation of the lighting apparatus 12.

The means by which the PCB powers the luminaire 54 is generally known in the art and is only briefly discussed herein. The PCB is configured to receive a supply voltage from the power leads 40 suitable for driving the luminaire 54. Typically the supply voltage will be 48V; alternatively a 60V may be used. The lighting fixture 26 may also be equipped with a suitable DC-DC converter to generate a 5V DC supply for the control electronics 55.

Having described the general arrangement of the lighting fixture 26, the construction of the luminaire 54 will now be described in further detail.

In this embodiment, the luminaire 54 comprises a surface-mount device light-emitting diode (SMD-LED) 82 which is thermally coupled to a heat pipe 84, by a suitable heatconducting bonding agent. The SMD-LED 82 comprises a mount 86, or substrate, which is fixedly mounted to a front surface 91 of a tubular support 88. The heat pipe 84 is received within an opening in the tubular support 88 and is fixed to a back surface of the mount 86. The mount 86 is formed of a conductive material so that thermal energy may be quickly transferred through to the transfer fluid housed within the heat pipe 84. A suitable material would be steel or aluminium but could also be a conductive polymer.

The tubular support 88 further comprises a collar 89, which extends from a back surface of the support 88. The collar 89 is configured to engage with and protrude through an opening 96 in the upper housing portion 58 of the lighting fixture 26. An oring 90 is arranged around the collar 89 such that it forms a seal between the upper housing portion 58 and the support 88 at the point where the support 88 protrudes through the opening 96.

SMD-LED devices are well known in the art so further detail will not be provided here for brevity. However, a suitable device is available from Citizen®, part no. CLL1300101C1. A single device is shown here, the output of which may be selected in dependence on the particular application. The SMD-LED 82 is typically configured to emit light with a wavelength of around 600-700nm (red) and 400-500nm (blue). The SMD-LED 82 may also be configured to emit light with a wavelength of sub-400nm (ultraviolet) These wavelength ranges correspond to the primary absorption peaks of Chlorophyll, which is the main photosynthetic pigment in green plants.

The heat pipe 84 is secured in place within the accessory port 92 by a connector 94 which is configured to support the heat pipe 84 inside the conduit-string 16. The connector 94 is configured to seal the heat pipe 84 within the accessory port 92 to prevent any fluid from leaking out of the conduit-string 16. The connector 94 is also configured to provide insulation to the heat pipe 84 such that any thermal energy that is extracted from the lighting fixture 26 is preferentially transferred to the conduit-string 16 where it may be dissipated away, rather than being conducted out into the air in the immediate vicinity of heat pipe 84.

The connector 94 is further arranged to support the weight of the lighting fixture 26 through its engagement with the heat pipe 84, which is fixedly coupled to the lighting fixture 26. To achieve this, an external surface of the connector 94 is such that it is configured so as to be removably engaged with the accessory port 92. The accessory port 92 is also threaded in the reverse manner in order to accommodate the connector 94. In an alternative embodiment of the invention described herein, the connector 94 is provided with a push-fit connector such as that which is commonly known in the art. Here, the connector 94 has an interior diameter of 10 mm such that it is configured to receive the heat pipe 84 within it and thereby form a snug fit against the exterior of the heat pipe 84. Additionally, an o-ring (not shown) is provided between the exterior of the heat-pipe 84 and the interior surface of the connector 94 in order to form a water-tight seal between those parts.

The connector 94 is made from any suitable material, for example an acetal copolymer material. Alternatively, the connector 94 may be formed from any number of engineering materials which exhibits suitable structural and thermos-insulating properties. Connectors 94 comprising the general structure and technical features of those that are described herein are available from John Guest Ltd, part no.

PM011012E.

The heat pipe 84 is arranged to protrude through the opening 96 in the upper housing portion 58 of the lighting fixture 26. It extends between lighting fixture 26 and the conduit-string 16, where it then penetrates through the accessory port 92. The heat pipe 84 extends upwardly into the conduit-string 16, towards the upper wall 22 of the internal fluid channel. In this way, the arrangement of the heat pipe 84 maximises the amount of its surface area that comes into contact with the fluid flowing through the conduit-string 16, which ensures that as much thermal energy may be transferred from the heat pipe 84 to the fluid passing through the conduit-string 16.

Figure 7 shows a perspective view of a lighting fixture of the lighting apparatus 12. The structure of the luminaire 54 and its integration with the heat pipe 84 assembly will now be described in more detail. As described above, the luminaire 54 includes an SMDLED, which is a type of LED module that uses surface-mount technology (SMT) to mount one or more LED chips onto a PCB. The SMD-LED 82 is a self-contained device designed either to function on its own or in combination with other SMD-LED devices. Advantageously, the SMD-LED 82 comprises a red, green, and blue diode to be mounted to a single PCB such that it can emit any colour of light by adjusting the level of output from each individual diode. Each diode is connected via a separate circuit, housed within the PCB, to a single power source. SMD-LEDs are also able to emit light of very high illumination whilst consuming relatively little power. The control offered by the SMD-LED 82 enables the emitted light to be tailored to meet the requirements of a particular growing environment.

The luminaire 54 may alternatively comprise a chip-on-board light emitting device (COB-LED). COB-LEDs typically comprise multiple diodes on a single semiconductor wafer substrate, which may be suitably connected to an external electrical supply by a single pair of contacts. A suitable COB-LED device is available from Citizen®, part no. CLU028. The COB-LEDs usually, but not always, include multiple LEDs integrated onto a single circuitized substrate, which is then fixedly attached to the mount 86. In this way, COB-LEDs minimize the space required for the light source, which reduces the complexity, and therefore the cost, of housing and packaging the luminaire 54 within the lighting fixture 26. The elimination of conventional device packaging also improves performance of the luminaire 54 as a result of the shorter interconnection path between the circuit board and the LEDs. The COB-LEDs also provide the added advantage of allowing for direct mounting of the LED light source to the heat pipe 84. COB-LEDs are directly mounted on, and electrically connected to, a circuit board instead of undergoing the traditional assembly steps associated with an individual LED package. This single circuit design simplifies the construction of the COB LED device. Although SMD LEDs and COB LEDs have been discussed here, it should be appreciated that other LED devices could also be used. Furthermore, it is a distinct advantage of the lighting apparatus 112 according to the present invention that the thermal management aspect of the system can be used with a variety of different LED technologies.

The structure and fabrication of the heat pipe 84 is well known in the art and is only briefly discussed herein. The heat pipe 84 is a heat exchanger with a substantially tubular structure. The main body of the heat pipe 84 includes a cylindrical outer casing which defines an internal chamber (or envelope), which contains water. Alternatively the heat pipe may contain another suitable vaporizable heat transfer medium, or fluid. The chamber is sealed at its distal end by a suitable closure such as rounded dome or a crimping. At an opposite end of the heat pipe 84, the internal chamber is sealed with a flat faced plug or cap (not shown) where the outer casing meets the back surface of the LED mount 86. The plug is typically soldered to the back of the LED mount 86 such that its end is placed in good thermal contact with the face of the mount 86. Alternatively, the end of the heat pipe 84 may be mounted to the mount 86 by a heat conductive bonding agent. Using either technique, the SMD-LED 82 is placed in good thermal contact with the end of the heat pipe 84.

It is envisaged that the end of the heat pipe 84 which is inserted inside conduit-string 16 may have a flattened end rather than the domed end as shown, for example, in Figure 5. With reference to Figure 8, a heat pipe 184 according to an embodiment of the invention comprises a flat faced plug or cap 185. Alternatively, the flat end may be formed integrally with the body of the heat pipe 185. As with the previously described embodiments, an opposite end of the heat pipe 184 is configured to be received within an opening in the collar 89 of the tubular support 88 such that it can be fixed to the rear face of the LED mount 86.

In use, the distal end of the outer casing defines a low temperature region of the heat pipe 84 and the LED mounted region defines a high temperature region. An inner wall of the internal chamber is lined with a material having capillary openings. The lining extends from the high temperature region to the low temperature region of the heat pipe 84 so as to enable the liquid transfer medium to rapidly travel between the high and low temperature regions.

During operation of the lighting fixture 26, thermal energy is transferred from the high temperature region to the lower temperature region of the heat pipe 84, such that a positive temperature gradient is established between the high and low temperature regions of the heat pipe 84. The heat pipe 84 affects the rapid transfer of thermal energy from the high temperature region to the low temperature region by first causing the heat transfer medium to vaporise in the high temperature region. The evaporation of the transfer medium in the high temperature region extracts heat from the SMD-LED 82. The transfer medium then permeates through to a portion of the envelope wall in the low temperature region. Since this portion of the envelope wall is situated in the low temperature region it is cooled by the fluid being circulated through the first fluid conduit, the transfer medium vapour condenses on the wall of the heat pipe 84. Condensation of the transfer medium therefore releases thermal heat energy into the fluid of the first fluid conduit.

Having transferred the thermal energy from the high to the low temperature regions of the heat pipe 84, the condensed heat transfer medium is collected by the capillary lining and propelled, by capillary action, to the high temperature region of the envelope where it is re-evaporated and, thus, the heat transfer cycle repeats.

By absorbing and transferring the thermal energy away from the heat pipe 84, the first fluid conduit ensures that the temperature gradient is maintained within the heat pipe 84. This ensures that the heat pipe 84 can continue to extract heat from the lighting fixture 26 and transfer that energy into the fluid circulating in the conduit 16. In this way the first fluid conduit operates in synergy with the second fluid conduit (the heat pipe

84) to extract heat from the lighting fixture 26 more effectively than if either the first or second fluid conduit were used in isolation.

The heat pipe 84 shown in Figure 6 is shown as a representation only and so its internal details are not presented in detail. However, it would be clear to the skilled person that the heat pipe 84 described herein comprises the structure of a conventional thermal transfer device in which a wick and a vapour cavity are enclosed in a tubular casing.

As mentioned above, the structure and fabrication of SMD-LED 82 assembly is generally known in the art and is only briefly discussed herein with reference to Figure 7 by way of example. The layers of the SMD-LED 82 are fabricated using metal organic chemical vapour deposition (MOCVD). Other suitable fabrication processes are known in the art. The layers of the SMD-LED 82 generally comprise an active layer/region sandwiched between first and second oppositely doped epitaxial layers all of which are formed successively on a growth substrate. The growth substrate is made of a material which exhibits a very high thermal conductivity such as, for example, silicon carbide, which ensures that the total output power of the SMD-LED 82 is not limited by the dissipation of thermal energy through the substrate to the heat pipe 84.

Additional layers and elements may also be included in the SMD-LED 82, including but not limited to, a buffer layer, a nucleation layer, a contact layer as well as light extraction layers. The resulting emission from the SMD-LED 82 is a white light with a correlated colour temperature (CCT) ranging from 2000K to ΊΟ,ΟΟΟΚ. In certain embodiments, the lighting fixture may be configured to emulate the illumination conditions that the plants would typically receive from full sunlight.

The SMD-LED 82 further includes a conductive wire bond which forms an electrical contact 98 between a conductive pad 100 on a top surface of the SMD-LED 82 and the external current supply. Both the wire bond and the conductive pad 100 are formed of Cu or an alternative conductive material such as gold. Both the wire bond and conductive pad 100 are deposited using known methods. In operation, an electrical signal is applied to the pads 100 through the wire bond. The electrical signal is then spread across the SMD-LED 82 to initiate the illumination of the LEDs.

The operation of the lighting apparatus will now be discussed in more detail. During use of the lighting apparatus 12, a significant proportion of thermal energy that is produced during operation of the lighting fixture 26 is extracted by the heat pipe 84 in the form of heat. In this way the heat pipe 84 defines a second fluid conduit of the lighting apparatus 12. The thermal energy that is extracted by the second fluid conduit is transferred to the conduit-string 16. The heat pipe 84 is configured such that the fluid that is channelled through the first fluid conduit is placed in direct contact with the heat pipe 84. In this way the thermal energy that is first extracted from the lighting fixture 26 by the heat pipe 84 can be readily dissipated away from the heat pipe 84 by the first fluid conduit.

A key advantageous feature of the above described arrangement is that the heat pipe 84 is able to quickly extract thermal energy from the lighting fixture 26 to the conduitstring 16, which is then able to disperse the heat away from the heat pipe 84. In order for the lighting fixtures 26 to be able to operate at an acceptable illumination output and efficiency, the heat that is extracted by the heat pipe 84 must also be transported away from the heat pipes 84 and then dissipated further by the conduit-string 16. The capacity of the first fluid conduit to absorb and transfer thermal energy is large, relative to the heat pipe 84, partly due to the body of fluid that can be circulated through it. Thus, the first fluid conduit is able to simultaneously absorb the heat that is extracted through a plurality of heat pipes 84.

More generally, the illumination output and efficiency of the lighting fixtures 26 may be correlated to the rate at which heat can be extracted from the luminaire 54. Thus, the flow rate of the fluid within the first fluid conduit can be controlled to maximise the heat extraction from the light fixtures 26.

In order to achieve an optimum growing environment it is often necessary to vary the illumination of the lighting fixtures 26 to suit varying growing conditions. For example, diming, cyclic variation of intensity and/or phasing of the luminaires 54 is required to promote healthy plant growth. The light that is emitted from the luminaire may also be tuned to suit a specific plant variety and may also be actively adjusted during the growth cycle to suit the changing needs of a plant as it grows.

Advantageously, the lighting apparatus 12 is configured to vary the flow of fluid through the first fluid conduit in order to match the output of the lighting fixtures 26. For example, when the output of the lighting fixtures 26 is dimed the fluid flow through the system can be reduced, thereby reducing the aggregate or parasitic power consumption of the system. In this way, the lighting apparatus 12 can be utilised more efficiently to provide illumination that is adaptable to suit the requirements of a particular plant species. This is in contrast to a conventional heat sink arrangement, which acts a redundant weight to a lighting fixture when it is not in use.

Alternatively, the modular components of the lighting apparatus 12 can be arranged and configured to suit a variety of different applications. In particular, the modular design of the lighting apparatus 12 enables the first fluid conduit to be arranged in a variety of different arrangements and configurations, in order to suit the specific illumination output of a particular lighting fixture 26. For example, applications that require a luminaire 54 with a high illumination output may require that a plurality of heat pipes 84 are arranged in thermal contact with the single luminaire 54. Each of the heat pipes 84 may then be arranged to transfer heat to a conduit-string 16 as described above. In this configuration, a conduit element of the conduit-string 16 may be provided with a plurality of accessory ports to accommodate a plurality of heat pipes 84, each of which are connected to a single high powered luminaire 54.

Such a configuration may be adapted to enable a plurality of heat pipes 84 to simultaneously extract heat from the single high powered luminaire 54. It is envisaged that such a high-output SMD-LED 82 may have a substrate cross sectional area which will support the attachment of more than one heat pipe 84. This can, therefore, be exploited to improve the extraction of thermal energy from the SMD-LED 82 using multiple heat pipes 84, clustered together as a single unit.

Figure 9 illustrates an alternative embodiment of the lighting apparatus 112, which comprises a luminaire support 113 with a generally rectangular configuration. Referring also to Figure 10, the support assembly 110 comprises a hollow chamber or conduit 116 through which fluid can flow in order to dissipate heat from the luminaires 54 to the external environment. Baffles 102 are provided within the conduit to define a circuitous fluid channel 120 between an inlet port 134 and an outlet port 136, which are located at opposite ends of the channel 120. It should be appreciated that although the channel 120 serves to guide fluid around the chamber, the baffles 102 could be omitted for convenience of manufacture.

The support 113 supports a plurality of luminaires 154 that are rigidly suspended from an underside surface 124 of the supporting 110. In order to accommodate a plurality of heat pipes 184, the luminaire support 110 is configured to have a substantially planar structure, akin to a panel-type radiator, in which a plurality of accessory ports 192 are arranged in a two-dimensional array, or matrix, configuration. An input fluid supply hose 128 is provided to fluidly connect the inlet port 134 to a fluid-flow control unit (not shown) of the lighting apparatus 112. An output hose 132 is provided to also connect the outlet port 136 to the fluid control unit. The input hose 128 is arranged to supply fluid to the conduit 116 whereas the output hose 132 is arranged to return the fluid to the control unit. As with the previously described embodiments, the inlet and outlet ports 134, 136 are arranged to allow fluid to pass into and out of the internal channel of the conduit 116 and the fluid-flow control unit is configured to regulate the flow of fluid through the conduit 116.Thus, the luminaire support 110 is fluidly connected to a fluid supply system that is configured to supply fluid to, and retrieve fluid from, the conduit 116.

Each of the luminaires 154 is connected to the conduit 116 via a heat pipe 184. The luminaires 154 are, therefore, thermally coupled to the conduit that is formed within the interior of the luminaire support 110 such that any heat that is generated by the luminaires 154 can be transmitted to the fluid passing along the channel of the conduit 116. The luminaires 154 are spaced apart from each other along the conduit 116 so as to optimise the dissipation of heat into the fluid running through the conduit. The planar construction of the luminaire support 110 provides an enlarged volume through which fluid may flow across the array of heat pipes 184 which are inserted into the conduit through the array of accessory ports 192. Consequently, this configuration enables the plurality of heat pipes 184 to simultaneously extract heat from several luminaires 154 arranged in a matching array configuration.

The support 110 also includes a power supply assembly which is arranged to provide power to the lighting fixtures 126. A plurality of power cables 144 connect each of the lighting fixtures 126 to an external control unit, which is located remotely from the luminaire support 110. In embodiments, the luminaire support 110 may be adapted to carry the power cables 144 along an exterior surface of luminaire support 110 side wall. The control unit may be located on an upper or a side wall of the luminaire support 110.

It is envisaged that the support assembly 13, as described herein, is configured to support any number of alternative temperature sensitive accessory fixtures. Such accessory fixtures may require thermal energy to be dissipated away from them in order to function effectively. In such an embodiment, the conduit 16 of the support assembly 13 defines a first fluid conduit of a heat transfer system. The support assembly 13 includes an accessory port, and an accessory fixture which is engaged with the accessory port of the conduit. The accessory fixture includes a heat generating component and a heat pipe 84 configured to transfer thermal energy from the heat generating component to the conduit 16. In certain embodiments, the component includes a sensor configured to detect a parameter of the growing environment. The sensor may be a temperature sensor or alternatively a light sensor such as that which is commonly known in the art. Alternatively the component may include an LCD display. The heat transfer system is further configured to provide an electrical connection to the accessory fixture in a similar fashion to the lighting apparatus 12 described above.

Claims (32)

1. A lighting apparatus comprising:

a first fluid conduit, including an accessory port, and a lighting fixture engaged with the accessory port of the conduit;

wherein the lighting fixture includes a lamp unit, and a second fluid conduit configured to transfer thermal energy from the lighting fixture to the first fluid conduit.

2. The lighting apparatus of Claim 1, wherein the lamp unit comprises at least one light emitting diode (LED).

3. The lighting apparatus of Claim 2, wherein the lamp unit is a surface mounted LED device.

4. The lighting apparatus of any of claims 1 to 3, wherein the second fluid conduit is arranged to dissipate thermal energy from the lamp unit.

5. The lighting apparatus of Claim 4, wherein the second fluid conduit is arranged in direct thermal contact with the lamp unit.

6. The lighting apparatus of Claim 5, wherein the second fluid conduit is mounted to a back of an illuminating surface of the lamp unit.

7. The lighting apparatus of any of claims 1 to 6, wherein the second fluid conduit is a heat-pipe.

8. The lighting apparatus of Claim 7, wherein the second fluid conduit comprises a plurality of heat-pipes.

9. The lighting apparatus of any preceding claim, wherein the second fluid conduit is configured to protrude through the accessory port and extend into the interior of the first fluid conduit such that, in use, thermal energy from the lighting fixture is transferred directly to the fluid flow within the first fluid conduit.

10. The lighting apparatus of any preceding claim, wherein the second fluid conduit comprises a connector configured to removably engage with the accessory port of the first fluid conduit.

11. The lighting apparatus of Claim 9 or Claim 10, wherein the connector is configured to seal the second fluid connector within the accessory port such that, in use, the fluid flow is prevented from leaking out of the first fluid conduit.

12. The lighting apparatus of any preceding claim, wherein the first fluid conduit includes more than one accessory port carrying a lighting fixture.

13. The lighting apparatus of any preceding claim, wherein the first fluid conduit has an elongate tubular structure.

14. The lighting apparatus of any preceding claim, wherein the first fluid conduit comprises a plurality of conduit elements.

15. The lighting apparatus of any of claims 13 to 14, wherein the first fluid conduit comprises a connector provided between a pair of neighbouring conduit elements, the connector being configured to provide a fluid connection between those two conduit elements.

16. The lighting apparatus of any preceding claim, wherein the first fluid conduit incorporates a power supply conductor configured to supply power to the lighting fixture.

17. The lighting apparatus of Claim 16, wherein the power supply conductor is mounted to an external surface of the first fluid conduit.

18. The lighting apparatus of Claim 17, wherein the power supply conductor is received within a channel that is provided along an external surface of the first fluid conduit.

19. The lighting apparatus of any preceding claim, wherein the lighting fixture comprises a fixing clamp for removably fixing the lighting fixture to the first fluid conduit.

20. The lighting apparatus of Claim 19, when dependent on any of claims 16 to 18, wherein the fixing clamp comprises an electrical connector configured to provide an electrical connection between the power supply conductor and the lighting fixture when the fixing clamp is engaged with the first fluid conduit.

21. The lighting apparatus of Claim 20, wherein the fixing clamp is configured to overlay the power supply conductor and engage with a securing ridge that is provided on an external surface of the first fluid conduit, wherein the electrical connector is provided on a conduit facing surface of overlying fixing clamp such that it forms an electrical contact with the power supply conductor when the fixing clamp is engaged with the first fluid conduit.

22. The lighting apparatus of any preceding claim, wherein the first fluid conduit comprises an end cap configured to seal an exposed end of the first fluid conduit.

23. The lighting apparatus of Claim 22 when dependent on any one of claims 16 to 21, wherein the power supply conductor is received through a hole in the end cap.

24. The lighting apparatus of any preceding claim, wherein the first fluid conduit is provided with an input port and an output port configured, in use, to connect the first fluid conduit to an external pumping assembly for circulating fluid therethrough.

25. A heat transfer system for use in a lighting apparatus, comprising a first fluid conduit that defines an accessory port, and an accessory fixture engaged with the accessory port of the conduit; wherein the accessory fixture includes a heat generating component and a heat pipe configured to transfer thermal energy from the heat generating component to the first fluid conduit.

26. A heat transfer system of the Claim 25, wherein the accessory fixture is a lighting fixture.

27 A heat transfer system of Claim 25 or Claim 26, further comprising a pumping assembly configured to circulate fluid through the first fluid conduit.

28. A heat transfer system of Claim 27, further comprising a temperature control assembly configured to adjust the temperature of the fluid circulated through the first fluid conduit.

29. A heat transfer system of any of claims 27 to 28, further comprising a controller configured to control an operating parameter of the heat transfer system in dependence on receiving an input control signal.

30. A heat transfer system of Claim 29, wherein the input control signal is a measured parameter of the growing system.

31. A heat transfer system of Claim 30, wherein the measured parameter is a temperature value and/or a flow rate value of the fluid circulated through the first fluid conduit.

32. A plant growing system comprising the heat transfer system of any one of claims 25 to 31.