Patent number 8651704 is assigned to
The following quote was obtained by the news editors from the background information supplied by the inventors: "The functional source of heat from an LED is primarily from what will be called the 'back side' of the assembly--i.e. the location away from the 'front side' where the light is emitted. This is quite unlike conventional lighting sources such as incandescent, fluorescent, high intensity discharge, which do not have this division. This division between what will sometimes also be called a 'light side' (or 'front side') and a 'heat side' (or 'back side') therefore allows a novel approach to capturing the waste heat of lighting systems in a way that is not possible with conventional lighting. Since the heat is concentrated in a location away from the 'light side,' the space which is illuminated by the LED can remain relatively unaffected by heat from the LED. The space on the 'heat side' of the LED can be at least substantially enclosed for efficient capture of heat. Enclosing the space then allows a novel means of capturing, removing, and potentially repurposing the heat generated by LED or solid-state light operation. The term 'LED' is meant to include most if not all lighting uses of light-emitting diodes (LEDs) including but not necessarily limited to semi-conductor LEDs, organic light-emitting diodes (OLEDs), or polymer light-emitting diodes (PLEDs) as sources of illumination. However, the reference to different types of LEDs is not a limitation on the scope of the invention, which is applicable to most if not all solid-state lighting (SSL), which includes the different types of LEDs (e.g., semi-conductor LEDs, OLEDs, PLEDs). SSL refers to light emitted by solid-state electroluminescence.
"Buildings and other enclosed spaces are generally equipped with heating and cooling systems in order to maintain the comfort of occupants. In the summer, for example, when the temperature is warmer, the heating and cooling system will cool the building. In addition to the outside temperature, many factors can affect the temperature of an enclosed space. For example, most light fixtures produce some heat from the light source or the electrical system that provides power to the light fixture. Other electrical/electronic components such as computers and processors, lighting controllers, amplification and PA systems, etc., likewise produce heat. The heat from the light fixtures and other components is typically rejected (e.g. radiated or conducted) into the enclosed space, working against the building's cooling system. Consequently, heat from the light fixtures and other components can increase the total cost to cool the building. In addition to being expensive, the energy rejected from lighting systems and other components is usually wasted.
"Therefore, an effective way to manage heat in these circumstances could be beneficial. One example could be apparatuses, methods, and systems which allow the use of LED lighting and can be highly beneficial in that they can reduce the burden on HVAC systems by concentrating and exhausting heat outside of conditioned space or directing to other beneficial uses. The embodiments outlined below can also reduce the number and/or size of LED fixtures by increasing LED lumen output.
"Lighting fixtures and other electrical/electronic components can also be used in locations without climate control, such as outdoor sporting venues.
"Some LEDs can emit light in the infrared (IR) wavelength(s), (e.g., at least some IR wavelength(s) alone or in combination with other wavelength(s), such as visible (VIS) or ultra violet (UV), and thus might be considered to generate heat on the 'light side' or 'front side' of the LED. However, at least of majority of heat from such an LED is at the 'heat side' or 'back side' of the LED, so the principles of the invention described herein are applicable to this type of LED also. In these types of locations, adequate heat rejection can be difficult especially when a collection of solid-state electronics is highly concentrated. Solid-state sports lights on high poles are an example of a situation in which providing adequate ambient heat sinking capability can be difficult due to the given the requirements for construction many feet in the air. Fixture size and configuration is constrained due to factors such wind loads and aesthetic considerations as well as the need to limit fixture weight to avoid excessive construction costs. This could lead to inadequate heat sinking capability or performance constraints, and potentially damage or premature failure of lighting or other electrical/electronic components. Therefore, apparatuses, methods, and systems which allow the use of LED lighting for these applications and provide effective heat management can be highly beneficial.
"Examples of possible applications include, but are not limited to, illumination of indoor and outdoor spaces or areas. The principles could be applied to light generated by SSL sources for almost any application. Some additional examples include but are not limited to, illumination (including containing IR or UV wavelength(s)) for curing photo-sensitive materials such as in photo lithography. Other illumination or use of light applications are possible."
In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "Systems and methods are described for heat rejection management in LED and other solid-state lighting fixtures and devices. Some embodiments have application to management of heat produced by solid-state lighting fixtures (e.g., LED lighting) and systems. Some embodiments of the present invention include a solid-state light source, an enclosure, and a fluid transfer conduit. The solid-state light source, in some embodiments, can be considered a heat source which may have one or more solid-state light sources including but not limited to light-emitting diodes (LEDs) and may have power electronics which can be in various locations relative to the light sources such as LEDs including in physical contact, close proximity, or at some distance from the light source LEDs. At least a part of the heat source can be associated with a heat sink to dissipate heat generated by the heat source. The enclosure may have a plurality of walls. One wall may be at least partially transparent to allow light from the one or more LEDs to illuminate a desired target area. The solid-state light source may be mounted within the plurality of enclosure walls to divide the enclosure into two sections. The LEDs may be located in the first section facing a wall of the enclosure that is at least partially transparent. The heat sink may be located in the second section of the enclosure. The two sections may or may not be thermally insulated from one another. Alternatively, the enclosure may have a single section, having the LEDs or other solid-state light sources located on an outer mounting surface, having the 'heat side' of the solid-state light source in thermal communication with the enclosure or with the mounting surface. This can be particularly beneficial in outdoors fixtures.
"In some embodiments, the enclosure can include a fluid transfer conduit interface for interfacing with a fluid transfer conduit. The fluid transfer conduit allows fluid (e.g., air, gas, chilled or heated water, circulating groundwater, antifreeze solutions, refrigerant, etc.) to transport heat generated by the heat source away from the heat side or heat sink of the solid-state light source. The heat removed from the enclosure via the fluid transfer conduit may be moved by moving the fluid. Examples include but are not limited to vented from the building directly by exhausting the heated air or indirectly by means of a heat exchange method or device, supplied to one or more rooms within the building, supplied to the heating ventilation and air conditioning (HVAC) system, and/or converted to other forms of energy through use of a heat exchange method or device and/or other energy transfer systems or techniques. Other uses are possible.
"The fluid transfer conduit can connect multiple solid-state light sources within individual enclosures in some embodiments of the present invention. None, some, or all of the individual enclosures may include or be operably connected or associated to one or more independently controllable fans or pumps to force the fluid across the heat sink associated with the solid-state light source housed within the enclosure.
"One aspect of the invention comprises methods, apparatuses, and systems including one or more solid-state light sources, a fluid transfer method or component to bring fluid in proximity to each solid-state light source to transfer heat generated by operation of the light sources to the fluid, a method or component to move the fluid away from the light sources to either (a) manage the collected heat or (b) apply it to another location or purpose. Optionally, the heat transfer via the fluid can be from a heat sink and/or power source associated with the solid-state light sources. The heat can be optionally collected in an enclosure around at least the heat sides of the solid-state light sources. The enclosure can be thermally insulated and/or have a surface adapted to conduct heat away. The enclosure can be sealed.
"Another aspect of the invention comprises a system of multiple fixtures, each fixture having one or more solid-state light sources, and a transfer method or sub-system adapted to collect heat generated in each fixture by operation of the solid-state light sources and carry or transfer it to a location for management or application. The system can efficiently and economically collect and manage source-generated heat instead of allowing the heat to radiate, convect, or conduct at or around the fixtures without organized management. Methods and systems can be designed to transfer heat in a variety of ways. Optionally, the methods and systems can be selectively combined with other systems. Examples include but are not limited to HVAC, geo-thermal, heat exchange, or energy storage.
"Potential benefits of such heat management include not only collectable and beneficial use of heat. Potential benefits also include but are not limited to allowing increased operating power to the light source which can produce more light output, increased life of the light source, possible reduction of the number of light sources needed for a given lighting application, possible reduction in size, type, or function of other heat management apparatus or methods (e.g. heat sinks), possible reduction in cost or complexity of components, increase in service life, and reduction in maintenance and replacement costs, among others.
"Some embodiments include a method of cooling a lighting fixture and transferring the heat to a location more or less separated from the fixture. A method according to one aspect of the invention directs that heat extracted from such a fixture can be returned to a preferred desired or instructed location within a building, can be transferred to a location outside of conditioned space in a building, or can be transferred to an energy storage system. Examples include but are not limited to electrical energy storage in batteries, thermal energy storage in stored fluid (e.g. water) or transfer to ground or thermal mass systems, or transfer to remote heat sinks.
"Some embodiments include a method of cooling a lighting fixture and transferring heat from a fixture to a location more or less separated from the fixture. Some embodiments include a method of cooling a lighting fixture and reducing the heat load contribution from the fixture for an interior space that is conditioned (e.g. air conditioned, HVAC conditioned, or the like). Some embodiments include a method of cooling a lighting fixture, reducing the heat load contribution from the fixture for an interior space that is conditioned, and using the heat for useful purposes, such as e.g. heating conditioned space, conversion into other forms of energy, or recycling by heating water, etc.
"Some embodiments pump fluid through the fixture to reduce the operating temperature of the light source and/or power circuits. Some embodiments pump air through the fixture to reduce the operating temperature of the light source and/or power circuits. In some embodiments, the heated air can be optionally exhausted outside the building when the air-conditioning is operating. In some embodiments, the heated air can be optionally exhausted inside the building if the extra heat is desirable. Some embodiments pump liquid through the fixture to reduce the operating temperature of the light source and/or power components.
"Also envisioned are systems, methods, and apparatus which provide many benefits for solid-state lighting. These benefits can include at least some of the following: cooling a solid-state lighting fixture thereby allowing it to operate at higher wattage, reducing the size of the fixture and/or number of LEDs or other solid-state source(s), increasing lumen output; and providing benefits to an associated building or structure by managing heat generated by lighting. These benefits may be realized with lighting used in conditioned spaces by reducing the heat contribution to conditioned space; and/or if separate from HVAC system, can reduce load on cooling system due to what might be called a 'concentration advantage' of more efficient transfer due to higher heat density in the envisioned enclosures, and what might be called an 'isolation advantage' due to reduced conduction to associated structures; heat may be directed to a desired location such as outdoors, indoors for heating, indoors for conversion/recycling (e.g. through a heat exchanger to heat water, a thermocouple/thermopile, or peltier effect devices.
"Some embodiments of the present invention provide for a method for cooling solid-state lighting fixtures. According to some embodiments, a determination can be made as to whether a HVAC unit and HVAC ductwork installed throughout a building structure are delivering heated air, cooled air, or only ventilation throughout the building structure. Fluid flow through a fluid transfer conduit positioned to carry away heat from the solid-state sources can be adjusted to increase the temperature of the fluid with heat generated by the heat source. The fluid flow can then be routed or transferred to the heated, cooled, or untreated air in the HVAC ductwork, tubing or other transport mechanism.
"The envisioned embodiments have many other advantages related to the use of solid-state lighting as well. For example, certain building operation systems can benefit from better control of heat from lighting. Facilities which are sensitive to introduction of extra heat could benefit not only from the low heat rejection of LED or other solid-state lighting, but also from the ability to further isolate and extract the heat. Examples include but are not limited to walk-in coolers, freezers, scientific installations, for instance would benefit from lights which have a minimal impact on thermal loading of a room or building. Coolers and freezers could particularly benefit from using connections to existing refrigerant circuits to extract heat from solid-state light source fixtures. According to principles well known in the art, liquid phase refrigerant on what is sometimes called the `low side` of the refrigerant cycle could be used as the coolant in the enclosure. As heat is absorbed from the fixture, refrigerant vaporizes. The refrigerant is directed by action of the system to what is sometimes called the `high side` of the system whereupon the heat is released through condensation.
"Another aspect of the invention comprises integrating a ground or thermal mass with a method and system for collecting heat generated by one or more solid-state light sources during operation. The collected heat can be dissipated in a ground or thermal mass or a remote heat sink. Alternatively, a medium used to collect the light source heat could be circulated at or near the light sources, heat from operating the light sources carried away, and that heat applied or added to another heat management system. Examples include but are not limited to ground loops, geo-thermal, and other heat or energy exchange systems.
"The method and system could include monitoring, control, and switching sub-systems.
"Due to the concentration of heat on the back side of the solid-state light source assembly, it is relatively easy to isolate waste heat from conditioned space. The fact that little or no IR or UV light is emitted from most solid-state lights makes them better for locations for which light in the non-visible spectrum is unwanted or harmful. Since heat is drawn directly away from the light source and not from the entire fixture housing, it does not require transfer of air through the face of the fixture housing to remove heat. Therefore, the lighting system can be a sealed system that draws air from a remote space, other than the enclosed space the fixtures might be in, thus providing benefits for any enclosure or building that requires isolation of air, control of dust, etc.
"While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. As will be realized, the invention is capable of modifications in various aspects, all without departing from the scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive."
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