AU2019100178A4 - A Lighting System - Google Patents

Abstract

Abstract The present invention is a lighting fixture for use in a controlled environment horticulture or agriculture system for growing a crop, having a modular structure, including an elongate body that is adapted to be suspended from a ceiling above the crop, and at least one bank of lights arrayed along the underside of the elongate body. The elongate body acts as a solid heat exchanger for the at least one bank of lights, and the elongate body includes at least one liquid conduit within it that travels along the longitudinal axis of the elongate body. 11 'II / , '1 70/, 9 /0/' /0.7' / I, ,0'/ I I', 5 '<V / , A /0/A , 0,9/ /0/! '0 /0/" /' 0' 0, 0' * 0' 0' 0, I, / 0' 0/7' 0~ ;P/9 0> 5 FIG.1 j 0/' // 00,,! 0::

Description

A Lighting System

Scope of the Invention [0001] The present invention relates to lighting, heating and irrigation system for controlled environment horticulture facilities.

Background of the Invention [0002] Controlled environment horticulture/agriculture (CEH) provides a controlled environment in which the optimal growing conditions for a particular crop may be maintained, regardless of the ambient conditions in the vicinity of the controlled environment facility. As the crop grows from seedling to mature plant, the growing conditions may be changed accordingly, to always provide the optimal growing conditions for the maturity stage of the plant, during a particular crop cycle.

[0003] To maintain the controlled environment, CEH operates within an enclosed growing structure such as a greenhouse or other similar building where all, or most of the variables, such as light, humidity, CO2, nutrient concentration, temperature and irrigation are controlled and kept within optimal ranges that best suit the particular crop at the particular maturity stage within the crop cycle. This allows the maximum yield and value from the crop grown in the available space.

[0004] The provision of a controlled temperature, humidity and light consume most of the energy consumed by the CEH facility. In most CEH facilities, the temperature control and lighting systems operate independently, and often impact adversely on each other. Heat generated by the lighting system must be removed to prevent the crops receiving too much heat and having the excess heat damage or decrease the health and vitality or yield of the crop. The heat from radiant space heaters can damage lighting systems. Further, the air immediately surrounding lighting equipment is substantially hotter than the average air within the CEH, and therefore carries a much higher volumetric moisture load. When the lights are turned off and allowed to cool, the air surrounding the lights cools, and this raises the relative humidity levels.

2019100178 18 Feb 2019

This therefore increases the need for air exchange, which increases energy consumption to run the fans and to run the heaters to heat the replacement air.

[0005] In order to increase the energy efficiency of CEH facilities, incumbent High Pressure Discharge (HID) light sources are being replaced by high intensity LED light sources. LED light sources are substantially more efficient at converting electrical energy into photosynthetically reactive light. LED light source efficiency and durability are critically linked to their operating temperature. Approximately 80% of the electrical energy consumed by LED lighting systems is converted to heat. Substantial heat sinks are typically used to remove the heat. Due to the amount of heat involved, the heat sinks must be large and bulky to offer sufficient surface area so that enough of the heat can be radiated and thereby exchanged with the ambient air within the CEH. The use of large heat sinks is well known, and at an industrial scale, requires large amounts of material that is bulky and heavy, even if mechanical aids such as fans are used to increase the movement of air over the heat sink. There are significant problems associated with the use of bulky and heavy heat sinks as follows:

a) The aggregated mass load of the lighting system featuring the conventional heat sinks can quickly exceed the design load of the CEH structure. In such cases, large lighting system support structures need to be constructed and maintained, thereby substantially increasing the capital cost. The structures may also create an obstruction that interferes with the harvesting of the crop.

b) The material cost and transport cost of the heat sink becomes a dominant element of the production cost.

c) The large size of the heat sink may obstruct the incoming stream of natural light that would otherwise be incident upon the crop thereby driving up the need to use artificial lighting and its associated cost.

[0006] Some of the problems associated with HID lighting systems is that they generate a lot of heat, so there are limits on the proximal distance that a HID lighting system can have, relative to the crop it is operating upon. LED lighting systems run much cooler, and therefore the proximal distance may be much closer to the crop. HID lighting systems need to be kept at least 1,5m away from the crop, whereas LED lighting systems can be as close as 0.3m away.

2019100178 18 Feb 2019 [0007] This close coupling of light and crop creates its own challenges. The most significant is humidity control. The specific challenge arises as soon as the lights are switched OFF as part of the diurnal crop growth cycle from a triple interaction described below:

• When it goes dark the plants cease photosynthesis - and the consumption of water and CO2.

• When it goes dark the plants start transpiration - consuming O2 and releasing water in the air.

• When the lights are switched off the ambient air temperature falls and RH increases rapidly.

[0008] This interaction creates a humidity spike easily leads to condensation forming on the plant which is potentially harmful to the crop quality. Controlling the humidity spike requires large volumes of air in the CEH to be replaced very quickly, which is not only energy intensive, but also creates a substantial peak capacity requirement for mechanical equipment, thereby rendering it both less efficient at other times and more capital intensive. Replacing more air than required is particularly costly when the air inside the CEH requires heating. A similar effect occurs with HID lights requiring a much larger air volume exchange compared to a LED lighting system, but their more distant location from the plants creates a shallower RH peak of longer duration that is easier to manage.

[0009] It is therefore an object of the present invention to provide a lighting system for a CEH facility that ameliorates at least some of the aforementioned problems.

Disclosure of the Invention [0010] Accordingly, in one preferred form, the present invention is a lighting fixture for use in a controlled environment horticulture or agriculture system for growing a crop, having a modular structure, including an elongate body that is adapted to be suspended from a ceiling above the crop, and at least one bank of lights arrayed along the underside of the elongate body. The elongate body acts as a solid heat exchanger for the at least one bank of lights, and the elongate body includes at least one liquid conduit within it that travels along the longitudinal axis of the elongate body.

2019100178 18 Feb 2019 [0011] Preferably, the bank of lights is all, or at least predominately, made up of LED lights.

[0012] Preferably, the LED lights are selected to optimize their photosynthetically reactive radiation spectrum.

[0013] Preferably, at least one end of the module includes connector means that are adapted to engage with corresponding connector means on an at least one end of an adjacent module so that when a pair of modules are arranged end to end, the connector means enable two modules to be releasably joined together, and when joined, the at least one liquid conduit in each module is configured to run continuously through each of the modules.

[0014] Preferably, the module includes a coupler that is adapted to connect the respective ends to a pair of adjacent modules in end to end arrangement wherein the coupler enable two modules to be releasably joined together, and when joined, the at least one liquid conduit is configured to run continuously through each of the modules and the coupler.

[0015] Preferably, the elongate body of each module includes at least a pair of liquid conduits that are arranged in parallel.

[0016] Preferably, the first conduit provides an inflow path for the liquid, and the second conduit provides an outflow path for the liquid.

[0017] Preferably, lighting fixture includes a blind end fitting that is adapted to be releasably connectable to the opposite end of the elongate body to the fluid inflow and outflow ports of the first and second channels respectively, and if there are a plurality of modules arranged in series, the blind end fitting is adapted to be connectable to the end of the last module in the series, and when connected, the blind end fitting redirects the liquid flow from the first conduit to the second conduit so that a complete fluid flow circuit is formed with both the inflow and outflow ports located on the same end of the same module.

[0018] Preferably, the connector means, or the coupler, and the blind end fitting, include

2019100178 18 Feb 2019 electrical connector means that are adapted to electrically interconnect each module that provides power to the at least one bank of LED lights included in each module to a power supply.

[0019] Optionally, one end of the elongate body includes male connector means, and the opposite end of the elongate body includes female connector means, and one of the ends includes means to releasably connect the liquid inflow port to a supply of liquid, and the opposite end includes means to releasably connect the outflow port to a drain.

[0020] Preferably, one end of the elongate body includes connector means that are adapted to releasably connect the liquid inflow port to a supply of liquid, and to releasably connect the outflow port to a drain.

[0021] Preferably, the liquid flowing through the elongate body is fertigation fluid.

[0022] In another preferred form, the present invention is a system for lighting a controlled environment horticulture or agriculture crop using at least one lighting fixture as previously described wherein at least one of the lighting fixtures includes temperature sensing means that are adapted to feedback temperature data to a logic control means. The logic control means include means to control the operation of at least one pump and the associated fluid flow rate through the lighting fixture so that the temperature of the lighting fixture is kept within a pre-set range of temperatures that is deemed optimal for the particular crop being lit by the lighting fixture.

[0023] In another preferred form, the present invention is a system for lighting and irrigating a controlled environment horticulture or agriculture crop using at least one lighting fixture as previously described wherein at least one of the lighting fixtures includes temperature sensing means that are adapted to feedback temperature data to a logic control means. The logic control means include means to control the operation of at least one pump and the associated fluid flow rate through the lighting fixture so that the temperature of the lighting fixture is kept within a preset range of temperatures that is deemed optimal for the particular crop being lit by the lighting fixture, and wherein the elongate body of the lighting fixture includes at least one additional liquid channel that is adapted to act as a sprinkler, and the logic control means are adapted to control the pump so that fluid flows through the at least one additional channel as required.

2019100178 18 Feb 2019

Brief Description of the Drawings [0024] Figure 1 is an isometric view of a lighting fixture used in the present invention, arranged for suspension above a crop in a controlled environment horticulture or agriculture facility.

[0025] Figure 2 is a side view of the lighting fixture shown in Figure 1.

[0026] Figure 3 is an end sectional view of the lighting fixture shown in the previous figures.

[0027] Figure 4 is a side view showing a plurality of lighting fixtures interconnected according to one preferred form of the present invention.

[0028] Figure 5 illustrates the advantages of the present invention over the prior art.

Description of the preferred embodiments [0029] Turning to Figure 1, we can see a lighting fixture 1 including an elongate body 3. The elongate body 3 is constructed out of a suitable material so that a substantial amount of the material used in the elongate body 3 acts as a heat sink for the lighting fixture 1. Optionally, an additional fin 7 may be included to increase the surface area of the heat sink that is in contact with ambient air. The elongate body 3 includes at least one bank of lights 5. In this illustration, four are included, with two banks on each side of the longitudinal line of the elongate body 3. Preferably the lights are an array of LED lights, and preferably each array includes LEDs that are all the same colour and intensity. However, other types of lights could be used, and/or LEDs of varying colours and intensity could be included in the array without departing from the scope of the present invention. In this illustration, the elongate body 3 includes both an inflow and outflow liquid channel. These channels run substantially along the entire length of the elongate body 3, in parallel. It is also possible that the elongate body 3 only includes one liquid channel. In this option, the liquid flows in only one direction, through the channel. In this illustration, the inflow channel and the outflow channel are connected into a fluid circuit, and the liquid supply is able to be releasably connected to the inflow channel via the inflow connector 13, and liquid is able to drain out of the elongate body 3 via outflow connector 15. The flow of the liquid through

2019100178 18 Feb 2019 the elongate body 3 removes a substantial amount of heat from the elongate body 3, and substantially augments the normal convective heat transfer of the elongate body 3 and fin 11 with the ambient air. In this example, the elongate body 3 is fitted with a pair of connector brackets 9 that connect to a ceiling bracket. This allows the lighting fixture to hang from a ceiling or other support structure above the crop.

[0030] Turning to Figure 2, we are shown an alternative embodiment of the present invention where the light fitting 1 only includes a single liquid channel, and the light fixture 1 is designed to have the fluid flow along its length in one direction only. The inflow port 13 and the outflow port 15 are at opposite ends of the light fixture 1.

[0031] Turning to Figure 3, we are shown a sectional end view taken though the lighting fixture

1. In this view, we are shown the variant that includes an inflow channel 21 and an outflow channel 23. The two channels are arranged in parallel and extend the entire longitudinal length of the elongate body 3. Heat generated by the LEDs 17 in the banks of lights is transferred via conduction into the material that makes up the elongate body 3. As liquid flows through the pair of channels, 21 and 23 respectively, heat is removed from the elongate body 3 and transferred into the liquid. Heat is also transferred with the ambient air from the surface of the elongate body, and from the fin 7. In this embodiment, the fin 7 also connects the lighting fixture 1 to the ceiling support 11.

[0032] Turning to Figure 4 we are shown another preferred embodiment of the present invention. In this embodiment, a series of lighting fixtures 1 are connected end to end. The invention covers a range of scenarios. As illustrated in this view, each lighting fixture 1 is connected to its adjacent lighting fixture 1 via a coupler 25. Ia preferred embodiment, each of the lighting fixtures 1 has a separate liquid circuit. The liquid supply and drain conduits 29 are each connected to a respective coupler 25. In this embodiment, the system can independently control the temperature of each light fixture in the system. In another embodiment, only the first light fixture in the series is connected to the supply and drain conduits, and the coupler interconnects the liquid channels inside each fixture so that there is a continuous fluid conduit circuit. The end most fitting is a blind end fitting. In an alternative embodiment, no couplers 25 are required, and instead, the respective ends of each lighting module is capable of

2019100178 18 Feb 2019 interconnecting with its adjacent module. The coupler 25 also may interconnect the electrical power supply so that the power supply is available to each bank of lights on each light fixture 1.

[0033] Turning to Figure 5, we are shown a pictorial comparison of the fundamental advantages of the present invention over the prior art. In the prior art, a large heat sink 31 are used to conduct heat away from the lights and exchange that heat with the ambient air. These massive heat syncs are heavy and tend to significantly block any natural light that is incident upon the crop, particularly coming into the controlled environment from the ceiling. By comparison, the size of the light fitting 1 of the present invention is significantly smaller, so any shadow it may cast on the crop is significantly smaller. The cost of materials to construct a light fitting 1 in accordance with the present invention is substantially cheaper, due to the savings in material required. Another major advantage of the present invention is the comparative light weight. This makes the light fittings easier and cheaper to manufacture and transport. It also reduces the load on the ceiling or other support structure that is used to suspend the light fittings above the crop, so therefore the ceiling or support structure does not need to be as heavily reinforced.

[0034] In a preferred embodiment, each lighting fixture 1 includes at least one temperature sensor. This sensor is adapted to send the temperature reading for that particular light fitting 1 back to a logic control means. The logic control means are adapted to control a pump. The system is able to keep each of the light fittings in use within a pre-selected temperature range that is deemed to be the most suitable for the particular crop.

[0035] In another preferred embodiment, at least some of the light fittings include at least one additional channel that is adapted to act like a sprinkler. When required, the logic control means may engage the pump, and any other ancillary equipment, such as flow control valves, so that liquid is pumped into the at least one additional channel, thereby causing it to irrigate the crop.

[0036] The present invention utilizes fertigation fluid as a cooling liquid within the heat sink associated with the lights. This provides the following direct benefits:

a) It reduces light fixture surface temperature to less than 30°C in a 25°C ambient, enabling air at a given pressure to carry 33% more water vapour mass per air mass, whereas heating air to 60°C increases the water vapour mass ratio by over 100%. Thereby reducing water

2019100178 18 Feb 2019 vapour mass in the air proximate to lights and crops by at least 2/3rds resulting in a much smaller post switch-off RH peak.

b) It allows the size of the light fixture to be reduced to the point where it presents no significant shading. The present invention is typically 50mm wide and a conventional air cooled light is typically 400mm wide

c) The lighting system can be integrated with the irrigation system to irrigate the crop.

d) It allows the light fixture to be constructed using only about 3% of the aluminium of a conventional heat sink, therefore it is much more cost effective. The typical mass of a conventional air-cooled light with similar thermal performance would be 45kg per lineal meter whereas the invention mass including fluid would be about <2kg per lineal meter.

e) The use of fluid cooling within the heat sink reduces LED junction temperature from typically 85°C to <40°C.

f) The reduction of LED junction temperature increases lighting efficacy by between 10% and 50% (depending on LED colour). It also increases LED life by at least 300%.

g) IT significantly reduces the amount of energy supplied to the lighting that would have otherwise been dumped into the surrounding air in the space above the plants. It is estimated that the present invention captures >60% of the energy supplied to the lighting system. This enables the lighting system to maintain the temperature of the plants within a desired 25°C 26°C. This recovered heat energy can be applied directly where needed elsewhere in the CEH system such as to bring the fertigation fluid delivered into the environment up to pre-set temperature range.

h) Energy recovered daily from lighting is estimated to be >5MWh/ha, which is a saving of around 35% of the overall CEH system’s daily energy needs. The additional energy required to circulate fertigation fluid through the LED lights is <3% of the LED light’s energy requirement i.e. less than 1/3 of the worst-case efficacy improvement delivered by the lower LED operating temperature.

i) Aggregating the 10% LED operating efficiency gains and 60% lighting energy recovery of the invention projects an overall CEH system energy use of 7.8MWhr/day or 54% energy saving referenced to conventional technology. In addition to this the daylight shading impact of the invention is 88% less than a conventional system of equivalent performance increasing the overall crop yield.

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2019100178 18 Feb 2019 [0037] While the above description includes the preferred embodiments of the invention, it is to be understood that many variations, alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the essential features or the spirit or ambit of the invention.

[0038] It will be also understood that where the word “comprise”, and variations such as “comprises” and “comprising”, are used in this specification, unless the context requires otherwise such use is intended to imply the inclusion of a stated feature or features but is not to be taken as excluding the presence of other feature or features.

[0039] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that such prior art forms part of the common general knowledge.

Claims (5)

1. A lighting fixture for use in a controlled environment horticulture or agriculture system for growing a crop, having a modular structure, including an elongate body that is adapted to be suspended above the crop, and at least one bank of lights arrayed along the underside of the elongate body, wherein the elongate body acts as a solid heat exchanger for the at least one bank of lights, and the elongate body includes at least one liquid conduit within it that travels along the longitudinal axis of the elongate body, and wherein the bank of lights is all, or at least predominately, made up of LED lights, and wherein the LED lights are selected to optimize their photosynthetically reactive radiation spectrum.

2. The lighting fixture as defined in claim 1 wherein at least one end of the module includes connector means that are adapted to engage with corresponding connector means on an at least one end of an adjacent module so that when a pair of modules are arranged end to end, the connector means enable two modules to be releasably joined together, and when joined, the at least one liquid conduit in each module is configured to run continuously through each of the modules.

3. The lighting fixture as defined in claim 1 wherein the fixture includes a coupler that is adapted to connect the respective ends to a pair of adjacent modules in end to end arrangement wherein the coupler enable two modules to be releasably joined together, and when joined, the at least one liquid conduit is configured to run continuously through each of the modules and the coupler.

4. The lighting fixture as defined in either claim 2 or claim 3 wherein the elongate body of each module includes at least a pair of liquid conduits that are arranged in parallel, and wherein the first conduit provides an inflow path for the liquid, and the second conduit provides an outflow path for the liquid, and wherein the lighting fixture includes a blind end fitting that is adapted to be releasably connectable to the opposite end of the elongate body to the fluid inflow and outflow ports of the first and second channels respectively, and if there are a plurality of modules arranged in series, the blind end fitting is adapted to be connectable to the end of the last module in the series, and when connected, the blind end fitting redirects the liquid flow from the

2019100178 18 Feb 2019 first conduit to the second conduit so that a complete fluid flow circuit is formed with both the inflow and outflow ports located on the same end of the same module.

5. A system for lighting and irrigating a controlled environment horticulture or agriculture crop using at least one lighting fixture as previously described wherein at least one of the lighting fixtures includes temperature sensing means that are adapted to feedback temperature data to a logic control means, and wherein the logic control means include means to control the operation of at least one pump and the associated fluid flow rate through the lighting fixture so that the temperature of the lighting fixture is kept within a pre-set range of temperatures that is deemed optimal for the particular crop being lit by the lighting fixture, and wherein the elongate body of the lighting fixture includes at least one additional liquid channel that is adapted to act as a sprinkler, and the logic control means are adapted to control the pump so that fluid flows through the at least one additional channel as required.