Surface radiator, device with the surface radiator and use of the surface radiator

Description

[0001] The invention relates to a surface radiator with a light-emitting semiconductor component and to a device equipped with such a surface radiator for illumination, for carrying out a photochemical reaction or for disinfection, and to a use of such a surface radiator also for carrying out a photochemical reaction or for disinfection.

[0002] It is known from the prior art to use floodlights with directed light emission to achieve uniform illumination of a surface. A floodlight therefore has a one-sided radiation characteristic, although the radiation angle can vary. Due to their significantly lower energy consumption, floodlights with light-emitting semiconductor components such as light-emitting diodes (LEDs) are increasingly being used to emit light over large areas. LEDs have a long service life and high switching stability, even when suddenly at full luminous flux. Although LEDs do not emit heat, high temperatures, which can occur during operation depending on the arrangement and power of the LEDs, significantly shorten their service life. To avoid this adverse effect, LEDs are often operated below their rated power, rather than at their rated power, which results in reduced luminous output.In order to still achieve the desired amount of light, the number of LEDs used is increased.

[0003] To create floodlights, the LEDs are arranged on a substantially flat, usually rectangular support surface within a housing frame behind an emission window. They can be surrounded by a reflector frame to adjust the radiation characteristics. Floodlights with a very large number of LEDs can be mounted in groups on a circuit board, which contains conductor tracks for electrical contact between the LEDs and, if necessary, ballasts (LED drivers) for control. The conductor tracks usually run to an edge of the circuit board to enable electrical connection. The disadvantage is that the heat generated during operation can be insufficiently dissipated by the circuit board.

[0004] EP 2 701 473 A2 therefore proposes using a circuit board for an LED floodlight that provides flat conductor track segments that form a comparatively large interface with the surroundings of the circuit board. The flat conductor track segments are intended to dissipate the waste heat generated by the LEDs from the circuit board into the surroundings.

[0005] To significantly improve heat dissipation, metal housings, usually made of aluminum, are used. For example, DE 20 2011 050 253 U1 discloses a lighting device with a plurality of LEDs arranged on a carrier unit designed as a printed circuit board. The lighting device further comprises an H-shaped aluminum profile body with two sections, wherein the carrier unit with the LEDs is arranged on a first section of the profile body. A translucent polymer sheath encloses the carrier unit with the LEDs and the first section. The second section of the profile body, which protrudes from the polymer sheath, serves to dissipate heat to a housing body.

[0006] In industrial applications with high-performance diodes that are operated with high currents for photochemical reactions with a high luminous efficacy or radiation intensity, even more effective heat dissipation is required to maintain the service life of the LEDs.

[0007] WO2020 / 148289 A1 describes a planar light source with LEDs for curing printing inks or varnishes, wherein at least one light-emitting semiconductor component (as an LED module with an associated circuit board) is arranged on a carrier plate. The light source further comprises a distribution element designed as a housing, on which an emission window is arranged, which overlies the at least one LED module. Furthermore, the housing-distribution element has a cooling channel connected via a connecting element to connections for the inlet and return of a cooling fluid. Several carrier plates with LED modules can be arranged on the housing-distribution element, wherein a surface of each carrier plate facing away from the LED module is designed as a cooling surface, which is arranged in a sealed manner on the distribution element. The cooling surface thus partially delimits a fluid path that is connected to the cooling channel in the distribution element via channel branches.

[0008] DE 20 2014 103329 U1 relates to a headlight with a liquid-cooled LED light source. To improve cooling, the LED light source can be arranged on a radiator with separate liquid cooling or attached to a cooling element that is arranged with the LED light source within the housing and also has the coolant flowing around it.

[0009] US 2017 / 030567 A1 also discloses a liquid-cooled LED lamp, and CN 108 180 403 A discloses a liquid-cooled laser light-emitting device.

[0010] KR 2016 0100712 A discloses an LED surface emitter with a housing body in which two cooling channels are formed, which are covered by a metal plate with LEDs mounted thereon. Fluid openings are formed in the metal plate adjacent to the LEDs on both sides, each of which communicates with one of the two cooling channels. An emission window, spaced apart from the circuit board with the LEDs, is fluid-tightly connected to the housing body, so that a fluid path for an electrically insulating and transparent coolant extends between the cooling channels through the fluid openings along the LEDs.

[0011] Based on this prior art, it is the object of the present invention to provide a surface radiator which is improved with regard to heat dissipation and thermal decoupling of the light-emitting semiconductor elements.

[0012] This object is achieved by a surface radiator having the features of claim 1.

[0013] The further object of providing a device for illumination, carrying out a photochemical reaction or disinfection which is improved with regard to heat dissipation and thermal decoupling of the light-emitting semiconductor elements of a surface radiator is achieved by a device having the features of independent claim 10.

[0014] A use of a surface radiator which is improved with regard to heat dissipation and thermal decoupling of the light-emitting semiconductor elements is disclosed by the use of the device having the features of independent claim 12.

[0015] Further training is described in the respective subclaims.

[0016] According to a first embodiment, a surface radiator according to the invention has at least one light-emitting semiconductor component and a housing body with at least one cooling channel for a coolant. A surface radiator typically comprises a plurality of light-emitting semiconductor elements (LEDs) arranged side by side at equal intervals on a substantially planar surface for unidirectional light emission. The cooling channel forms at least part of a fluid path extending from an inlet opening for the coolant to a return opening for the coolant. The inlet opening and the return opening are formed on the housing body and are preferably intended for connection to a coolant circuit. An emission window is arranged on the housing body and defines a front side of the surface radiator, at which the unidirectional light emission occurs.An "emission window" is understood here as a plate or disk made of a material that is transparent to the radiation emitted by the at least one light-emitting semiconductor component, which—depending on the intended use of the surface radiator for illumination, for conducting a photochemical reaction, or for disinfection—is defined by at least one predetermined wavelength or at least a predetermined wavelength range of electromagnetic radiation. "Transparent" here means that the emission window has a transmittance of at least 75% for the radiation. The dimensioning of the emission window and its arrangement on the housing body correspond to the arrangement of the one or more LEDs, so that the emission window overlies the at least one light-emitting semiconductor component.

[0017] The housing body itself provides a mounting surface for the at least one light-emitting semiconductor component, spaced apart from the emission window, without the need for an additional support structure as in the prior art, wherein the mounting surface for arranging the LED(s) corresponds to the emission window. The arrangement of the emission window on the housing body is fluid-tight, so that a sealed emission space is defined by the housing body, the semiconductor component, and the emission window. The fluid path provided for cooling the LED is then defined by i) at least one first cooling channel extending from the inlet opening through the housing body to one or optionally several outlet openings formed on a first side next to the fastening surface and opening into the emission chamber, and ii) the emission chamber from the outlet opening to one or more outlet openings formed on a second side facing away from the first side next to the fastening surface in the housing body, so that the fastening surface lies between the outlet opening and the outlet opening and the emission chamber is completely filled with the coolant, and iii) at least one second cooling channel extending from the outlet opening through the housing body to the return opening.

[0018] Since, according to the invention, the coolant floods the emission chamber and comes into direct contact with the LEDs to more effectively dissipate the heat generated by the LEDs during operation, the coolant according to the invention is an electrically insulating liquid that is transparent to the input radiation emitted by the light-emitting semiconductor component and, due to its specific heat capacity, density, and thermal conductivity coefficient, ensures better heat transfer than with a gaseous cooling medium or air. Transparency is understood herein to mean a transmittance of at least 75% for the input radiation with respect to the path length defined by the distance between the LED and the emission window.Advantageously, by flooding the emission chamber with the liquid coolant, which is fed from the first cooling channel through the outlet opening and discharged through the drain opening into the second cooling channel, not only can heat be absorbed by the LEDs, but heat can also be absorbed from the environment via the emission window, which can then be dissipated outside the surface radiator. This prevents heat buildup between the LEDs and the emission window, keeps the temperature of the LED constant, and thermally decouples the surface radiator from the environment. A further advantage of flooding the emission chamber with the liquid coolant is the prevention of condensation in the event of a large temperature gradient to the environment or the irradiated surface.

[0019] According to the invention, a connection chamber open to the emission space is formed on the front side of the housing body adjacent to the fastening surface. A connection opening is formed on the housing body and is connected to the connection chamber, with at least one connection line for connecting the at least one light-emitting semiconductor component extending at least into the connection chamber. A ballast is provided on a circuit board, by means of which a plurality of the light-emitting semiconductor components are fastened to the fastening surface. On a side of the circuit board close to the connection chamber, a pair of connection contacts for a row of light-emitting semiconductor components is formed on the circuit board, with each connection contact being connected to a respective connection line, with the ballast being provided between the connection contacts and the light-emitting semiconductor components (LEDs).Or the ballast for the at least one light-emitting semiconductor component is arranged connected to the at least one connecting line in the connecting chamber.

[0020] This means that on the front side of the housing body, adjacent to the fastening surface, a connection chamber can be formed which is open to the emission space and is used to accommodate electrical connection elements for the LED and which, like the emission space, is filled with the coolant. Furthermore, a connection opening is formed on the housing body, wherein the arrangement of the connection opening on one of the side surfaces or the rear side of the housing body, like the arrangement of the inlet and return openings, can be selected to suit the installation context. As electrical connection elements for connection to a power supply outside the housing body, at least one connection line for connecting the at least one light-emitting semiconductor component extends at least into the connection chamber and optionally into or through the connection opening.

[0021] Furthermore, a surface radiator according to the invention comprises a plurality of light-emitting semiconductor components, in particular a plurality of LEDs, arranged on a circuit board, possibly on several, with which the light-emitting semiconductor components are attached to the mounting surface of the housing body. A pair of connection contacts for a row of light-emitting semiconductor components is formed on the circuit board on a side of the circuit board near the connection chamber, with each connection contact being electrically connected to a respective connection line. A "row" of LEDs here refers to a predetermined number of LEDs on a circuit board, which can preferably be arranged in a straight line over the length of a circuit board, but can also be arranged in a different pattern, e.g., in a zigzag pattern. A surface radiator can comprise a circuit board with a row of LEDs, preferably with several parallel rows of LEDs.By arranging the connection contacts on the side of the connection chamber, the length of the connecting cables can be minimized and routing the cables through the emission chamber can be avoided. This not only prevents shading of the LEDs but also protects the cable sheath materials, for example, from UV radiation. The electrically conductive connection of a connecting cable to a connection contact can be soldered, for example, to avoid insulation resistance caused by the coolant.

[0022] A ballast or LED driver required for operating the LEDs can be provided on the circuit board between the connection contacts and the LEDs. However, to minimize heat input from a ballast to the LEDs, it is preferably provided that the ballast for the light-emitting semiconductor component is arranged in the connection chamber and connected to one or more connection leads. The heat generated by the ballast is not conducted to the LEDs via the circuit board, but is transferred via the coolant to the housing body surrounding the connection chamber and / or dissipated from the emission chamber with the coolant.

[0023] Preferably, a coolant circuit can be provided, in which the coolant heated in the surface radiator is circulated in order to release the absorbed heat outside the emission chamber. Furthermore, flooding the emission chamber with the liquid coolant advantageously prevents near-field reflection between the LED and the emission window and prevents the presence of volatile organic hydrocarbon compounds (VOCs) in the emission chamber, which could damage the LEDs. In contrast to the use of an inert gas such as nitrogen, this method prevents accelerated aging of the LEDs' primary optics. VOCs ("volatile organic compounds") are particularly present in chemical plants and penetrate the primary optics, which are usually designed as silicone lenses, clouding them and thus reducing the light output.Since the primary optics are no longer exposed to a gaseous atmosphere, but are shielded by the coolant, the aging process is significantly slowed. To completely avoid the limitations in light output caused by the aging process of the primary optics, a floodlight according to the invention advantageously offers the possibility of dispensing with protective primary optics such as silicone lenses for the LEDs, since the liquid coolant already adequately protects the LED's semiconductor chip from environmental influences.

[0024] A surface radiator according to the invention is thus not only improved with regard to cooling the LEDs and thermal decoupling from the environment, but also protects the LEDs from harmful substances. Furthermore, a surface radiator according to the invention particularly advantageously provides increased overall light or radiation output compared to prior art lamps, since the liquid coolant increases the photon coupling efficiency at the phase boundary between the diode surface and the coolant in the emission chamber, and reduces reflection at the phase boundary between the coolant present in the emission chamber and the emission window.

[0025] In this context, "operational radiation" refers to electromagnetic radiation of specific wavelengths or wavelength ranges that are suitable for a predetermined use of the surface radiator, e.g., for illumination, conducting a photochemical reaction, or for disinfection.

[0026] A light-emitting semiconductor component can be a light-emitting diode (LED) or, preferably, an LED module consisting of at least one LED and a circuit board having conductor tracks for electrically connecting the at least one LED. A circuit board does not correspond to a carrier structure from the prior art: LED modules consisting of at least one LED and a circuit board are also used there. The modules are attached to the carrier structures, such as H-shaped carrier units or carrier plates with cooling surfaces, by means of the circuit board, and the carrier structures are arranged on a housing body.

[0027] LEDs, as used herein, refer to all light-emitting diodes, including organic light-emitting diodes (OLEDs), that emit electromagnetic radiation in the infrared, visible, or ultraviolet wavelength ranges. Furthermore, LEDs can have an emission spectrum with combined components in the infrared, visible, and / or ultraviolet wavelength ranges. To adapt the radiation emitted by an LED to its intended use, the LEDs are typically doped differently. For the emission of UV radiation, for example, diamond, aluminum nitride, aluminum gallium nitride, or aluminum gallium indium nitride are suitable doping materials.

[0028] According to a further embodiment of the surface radiator according to the invention, the housing body can have a rear side facing away from the front side and is delimited between the front and rear sides by side surfaces. The inlet opening and the return opening of the fluid path can be arranged jointly on one of the side surfaces or jointly on the rear side, or individually on different side surfaces, or individually on one of the side surfaces and the rear side. The arrangement of the inlet opening and return opening on the rear side and / or side surfaces of the housing body can be selected to suit the installation context of the surface radiator in a higher-level device for illumination, in particular for carrying out a photochemical reaction or for disinfection.The housing body can further be designed for arranging the surface radiator in such a higher-level device, for example, in that the housing body can have one or more installation elements such as fastening holes, tabs or collars.

[0029] A further advantageous embodiment of the surface radiator according to the invention provides that the outlet opening is formed on a side of the fastening surface facing away from the inlet opening, i.e. on the distant side. The first cooling channel runs at least partially in a plane parallel to the fastening surface through the housing body in order to open into the emission chamber in an area remote from the inlet opening. Because the first cooling channel extends below the fastening surface through the housing body, heat generated by the LEDs and absorbed by the housing body via the fastening surface can be transferred from the housing body to the supplied coolant as it passes through the first cooling channel. The housing body is preferably made from a thermally conductive material, particularly preferably aluminum.In this way, the temperature of the housing body can also be kept constant, so that the heat generated by the LEDs can be dissipated not only at the front through the direct contact of the LED with the coolant, but also at the rear through the housing body to the coolant. The at least one drain opening can preferably be formed on a side of the mounting surface close to or facing the return opening, so that the second cooling channel, through which the heated coolant is guided to the return opening, can be kept as short as possible.

[0030] Depending on the number and / or power of the LEDs, in particular with a larger number and / or higher power of the LEDs, a further embodiment of a surface radiator according to the invention can provide that the inlet opening is fluidically connected to a distribution channel section close to the inlet opening, from which a plurality of first cooling channels extend through the housing body and parallel to the fastening surface to the respective outlet openings. The second cooling channel can then extend from a collecting channel section, which is connected to a plurality of outlet openings, to the return opening. Alternatively, the first cooling channel can extend from the inlet opening to a distribution channel section remote from the inlet opening, on which a plurality of outlet openings are formed, wherein here too the second cooling channel extends from a collecting channel section, which is connected to a plurality of outlet openings, to the return opening.In a possible, less preferred alternative, the housing body can have a plurality of first cooling channels with a corresponding plurality of respectively assigned inlet and outlet openings and a plurality of second cooling channels with a corresponding plurality of respectively assigned outlet and return openings.

[0031] According to a further embodiment, a surface radiator according to the invention can have a holding frame which is arranged, preferably detachably, on the housing body for holding the emission window and is designed, corresponding to a window frame, to leave the light opening provided by the emission window uncovered or free for the at least one light-emitting semiconductor component. To seal the arrangement of holding frame and emission window on the housing body, a circumferential seal (e.g., by means of a sealing cord in a corresponding sealing groove in the holding frame and housing body) can be arranged between the holding frame and the emission window and between the emission window and the housing body.

[0032] As an alternative to attaching the emission window using a holding frame, in another embodiment the emission window can be attached to the housing body using an adhesive layer, which also ensures sealing. This can advantageously create a virtually edgeless design of the surface radiator, which can be particularly well suited for integration into a higher-level device. Furthermore, an embodiment is conceivable that combines the adhesive layer and holding frame when arranging the emission window on the housing body, for example if the emission window is sealingly fixed by an adhesive layer in a holding frame that can be detachably arranged on the housing body, so that only one circumferential seal is required to seal the holding frame or emission window on the housing body.

[0033] A further embodiment of the surface radiator according to the invention relates to the housing body having at least one fastening shoulder on the front side, which surrounds the fastening surface as a stepped circumferential edge, wherein a first fastening shoulder is designed to receive the emission window, i.e. as a support for the emission window. The path for the electromagnetic radiation through the coolant is thus defined by the height of the emission space by the spacing of the first fastening shoulder, on which the emission window rests, from the fastening surface. An embodiment with a second fastening shoulder, which surrounds the first fastening shoulder as a stepped circumferential edge, can be provided for arranging a holding frame for fastening the emission window to the housing body.

[0034] In a preferred embodiment, the connection opening can be connected to the connection chamber via a passage opening, wherein a cross-sectional area of the passage opening is smaller than a cross-sectional area of the connection opening in order to facilitate sealing of the connection opening with respect to the connection chamber filled with the coolant.

[0035] The passage opening can have a cross-sectional shape that deviates from the circular shape, for example a polygonal shape, or can be designed as a dihedral, for example, in order to enable a rotation-prevented arrangement of a correspondingly shaped connection element, such as a connection plug that is connected to the connection lines, or an adapter element through which the connection lines extend.

[0036] Thus, in a further embodiment, a surface radiator according to the invention can provide for the electrical connection in that the at least one connecting line extends at least partially through the through-opening from the connection chamber into the connection opening, or in that the surface radiator has a connecting plug which is connected to the at least one connecting line (optionally via a ballast), wherein the connecting plug extends at least partially into the connection opening, optionally also into the through-opening leading to the connection chamber. To prevent leaks due to an insulating sheath of the connecting lines or the connecting plug, the arrangement of the connecting plug (or the connecting lines) in the connection opening (and / or in the through-opening leading to the connection chamber) can be sealed by a potting or soldering compound.

[0037] Furthermore, according to one embodiment of a surface radiator according to the invention, the surface radiator can have an inlet connection element connected to the inlet opening for connecting a coolant supply line. The surface radiator also has a return connection element connected to the return opening for connecting a coolant return line. The connection of the inlet connection element to the inlet opening and / or the return connection element to the return opening is sealed with a casting or soldering compound to prevent leaks.

[0038] A device according to the invention for illumination, for carrying out a photochemical reaction or for disinfection has at least one surface radiator in an embodiment according to the invention with at least one light-emitting semiconductor component, the emission spectrum of which provides a corresponding application radiation for illumination, for carrying out a photochemical reaction or for disinfection.

[0039] According to a further embodiment of a device according to the invention for illumination, for carrying out a photochemical reaction, or for disinfection, the device comprises a housing. This includes not only a wall that completely surrounds a reaction chamber, but also mountings in a more general sense. Thus, the housing at least partially surrounds an illumination chamber, reaction chamber, or disinfection chamber and has at least one installation location for the at least one surface radiator. Preferably, the housing body of the surface radiator has at least one installation element for arrangement in the device at the predetermined installation location.

[0040] An inventive use of a surface radiator according to the invention is the illumination, carrying out a photochemical reaction or disinfection, wherein the at least one light-emitting semiconductor component of the surface radiator has an emission spectrum that provides a corresponding application radiation for illumination, carrying out a photochemical reaction or for disinfection.

[0041] Further embodiments, as well as some of the advantages associated with these and other embodiments, will become clearer and more easily understood from the following detailed description with reference to the accompanying figures. Items or parts thereof that are substantially the same or similar may be provided with the same reference numerals. The figures are merely a schematic representation of one embodiment of the invention.

[0042] Showing: Fig.1 a perspective view of the surface radiator according to an embodiment of the invention, Fig. 2a front view of the surface radiator according to the invention Fig. 1 with the cutting lines AA, CC, DD, EE, FF, Fig. 3 a cross-sectional view through the surface radiator Fig. 2 along section line AA, Fig. 4 a cross-sectional view through the surface radiator Fig. 2 along section line CC, Fig. 5 a longitudinal section through the surface radiator Fig. 2 along section line DD, Fig. 6 a longitudinal section view according to Fig. 5 through the housing body, the emission window and the mounting frame of the surface radiator in the disassembled state, Fig. 7 a longitudinal section through the surface radiator Fig. 2 along section line EE, Fig. 8 a longitudinal section through the surface radiator Fig. 2 along section line FF, Fig. 9a schematic perspective view of a housing body of a surface radiator according to the invention with fluid path a shown, Fig. 10 a front view of a surface radiator according to an embodiment of the invention with electrical connection elements, Fig. 11 a schematic longitudinal sectional view through a surface radiator according to a further embodiment of the invention, Fig. 12 a schematic front view of a surface radiator with a distribution channel near the outlet opening according to a further embodiment of the invention, Fig. 13 a schematic front view of a surface radiator with a distribution channel remote from the outlet opening according to a further embodiment of the invention, Fig. 14 a schematic front view of a surface radiator with a meandering first cooling channel according to a further embodiment of the invention, Fig. 15a schematic cross-sectional view through an LED with primary optics, which can be used as a light-emitting semiconductor component in a surface radiator designed according to the invention, Fig. 16 a schematic cross-sectional view through a primary optics-free LED which can be used as a light-emitting semiconductor component in a surface radiator according to a further embodiment, Fig. 17 a schematic side view of a device having a surface radiator according to an embodiment of the invention for carrying out a photochemical reaction, Fig. 18 a schematic side view of a device having a surface radiator according to a further embodiment of the invention for disinfection.

[0043] The present invention relates to an LED panel radiator, which is primarily intended as a high-performance radiator for industrial use, for example as a panel radiator in a device for disinfecting surfaces or for carrying out a photochemical reaction. For this purpose, the panel radiator can be mounted, for example, in a holder above the surface to be disinfected or in a wall element of a photoreactor, which can also be a reactor lid. Furthermore, an LED panel radiator according to the invention can also be designed for lighting purposes or as a heat radiator, which, as high-performance radiators, also require effective heat dissipation. Accordingly, the present invention also relates to any device for lighting, as well as, where appropriate,to devices for heat treatment, carrying out a photochemical reaction or disinfection, which have a surface radiator in an embodiment according to the invention, as well as to the use of a surface radiator according to the invention, in particular for illumination, but possibly also for heat treatment, carrying out a photochemical reaction or disinfection in general.

[0044] The structure of a surface radiator 100 according to the invention with many LEDs 2 arranged in a surface area and a housing body 1 is shown in Fig. 1 to 8 explained. Fig. 9 and 11 with their simplified, low-detail schematic representations show the principle of the device and in particular the fluid path a of the coolant K through a surface radiator 100 according to the invention. The surface radiator 100 has Fig. 11a different cooling channel design. In the surface radiator 100, the LEDs 2 arranged on a mounting surface 12 of the housing body 1 are overlaid by an emission window 5, which is arranged at a distance from the mounting surface 12 on the housing body 1 and is transparent to an insert radiation S emitted by the LEDs 2, which in Fig. 11is indicated by the dotted wavy arrows. The arrangement of the emission window 5 on the housing body 1 is fluid-tight, so that the housing body 1, the LEDs 2 arranged on the fastening surface 12, and the emission window 5, which defines a front side of the surface radiator 100, delimit an emission chamber 6 through which the fluid path a runs. The emission chamber 6 is thus completely filled with the coolant K, which thus directly contacts the LED 2 to absorb and dissipate the generated heat. A heat-conducting and electrically insulating liquid is therefore selected as the coolant K, which, like the emission window 5, is transparent to the radiation S.Thus, in a surface radiator 100 according to the invention, the fluid path a runs in the flow direction of the coolant K, starting from an inlet opening 3 formed on an outer wall of the housing body 1, through a first cooling channel 10, which extends through the housing body 1 to an outlet opening 13 in the emission chamber 6, which is formed on a first side adjacent to the fastening surface 12. From the outlet opening 13, the fluid path a runs through the emission chamber 6 to an outlet opening 14, which is formed on a second side facing away from the first side next to the fastening surface 12 and connects the emission chamber 6 to a second cooling channel 11, which leads through the housing body 1 to a return opening 4 on an outer wall of the housing body 1.

[0045] The coolant K filling and flowing through the emission chamber 6 effectively dissipates a significant portion of the heat generated by the LEDs 2 during operation due to the direct contact. Additionally, the housing body 1 can be made of a heat-conducting material, which can in particular be a metal material and particularly preferably aluminum or an aluminum alloy, so that a certain portion of the heat generated by the LEDs 2 can also be dissipated to the housing body 1 at the rear of the LED 2.

[0046] Preferably, the heat absorbed by the coolant K can be cooled outside the emission chamber 6 or outside the housing body 1 after being discharged through the return opening 4, and the cooled coolant K can be fed back into the circuit via the inlet opening 3. The surface radiator 100 can therefore have corresponding known elements for forming a coolant circuit. Furthermore, the coolant K filling and flowing through the emission chamber 6 also ensures thermal decoupling of the LED 2 from the environment adjacent to the emission window 5, in that the coolant K can also exchange heat with the environment via the emission window 5. Further advantageously, the coolant K filling the emission chamber 6 prevents near-field reflection between the LEDs 2 and the emission window 5 and prevents the occurrence of volatile organic hydrocarbon compounds (VOCs) in the emission chamber 6, which could damage the LED 2.Furthermore, filling the emission chamber 6 with the coolant prevents an explosive atmosphere. A surface radiator 100 according to the invention is therefore not only improved with regard to the cooling of the LEDs 2 and their thermal decoupling from the environment, but also protects the LEDs 2 from harmful substances and, moreover, particularly advantageously provides an increased total light or radiant output of the input radiation S compared to the prior art. This results from the fact that the liquid coolant K, which is preferably selected from saturated hydrocarbons, silicone oils, and synthetic ester and ether compounds and whose refractive index is significantly higher than that of air or inert gas and, for suitable cooling liquids, lies in the range of approximately 1.35 to approximately 1.55 (at 20°C), increases the photon outcoupling efficiency at the phase boundary between the diode surface and the coolant K in the emission chamber 6.The reflection at the phase boundary between the coolant K in the emission chamber 6 and the emission window 5 is reduced.

[0047] The radiation required for a specific application of the surface emitter, e.g., for illumination, conducting a photochemical reaction, or disinfection, is provided by LEDs whose doping ensures electromagnetic radiation with the wavelength(s) intended for the application. LEDs are known to cover not only the visible light but also the infrared and / or UV spectral ranges. The choice of material for the emission window and the coolant can therefore be limited by the wavelength range of the radiation used. For illumination, the radiation used is visible light, so the emission window is transparent at least for the part of the electromagnetic spectrum with wavelengths from approximately 380 to 780 nm.UV radiation (100-380 nm) can be used as input radiation for disinfection and for conducting photochemical reactions. Therefore, the emission window is made of a material that is transparent at least to the UV wavelengths used. For example, UV-C radiation (100-280 nm) is used for disinfection purposes. UV-B (280-315 nm) and UV-A radiation (315-380 nm) are used for many photochemical reactions, although photochemical reactions are not limited to this spectral range. The input radiation required to conduct photochemical reactions depends on the type of intended reaction or the absorption wavelength of a reactant molecule. Therefore, the input radiation for certain photochemical reactions may also be in the other wavelength ranges. Should reference symbols be included or removed here?

[0048] In principle, the emission window can also be transparent to wavelengths other than those of the input radiation. However, it may also be desirable - especially in the area of photochemical reactions - for the emission window to be transparent only to certain wavelengths, so that the emission window - through material selection or a coating - can also assume a filter function to filter out unwanted wavelengths. Selecting the window material, for example from various glass and plastic materials, depending on the wavelengths of the input radiation is a standard professional activity. For example, experts know that synthetic quartz and high-boron borosilicate glasses still have good transparency in the UV-C range. Glass ceramics also exhibit good transparency in the infrared spectral range and can be used as window materials there.If the intended application involves conducting a photochemical reaction, care must be taken when selecting a window material to ensure that no reactions occur with the reactants or products. Accordingly, the coolant is selected from electrically insulating liquids depending on the spectral range of the respective radiation used. Window materials and coolants are considered "transparent" if they each exhibit a transmittance of at least 75% for the wavelength(s) of the radiation used along the respective path through the emission window or through the emission space between the LED surface and the emission window.

[0049] The liquid coolant for radiation in the visible and UV spectral range can be selected, for example, from highly refined mineral oils, which consist almost exclusively of alkanes and cycloalkanes, i.e., saturated hydrocarbons. Alkanes and cycloalkanes are advantageously transparent from the visible wavelength range up to the broad UV-C range (220-230 nm). Below this range, transmission decreases but can still be sufficient for wavelengths down to 195 nm and below, especially if the path distance between the LED and the emission window is sufficiently short. Cycloalkanes may be preferred due to their higher refractive index compared to the corresponding linear alkane. Thus, the refractive indices (20°C) for C 5 -C 14 cycloalkanes extend over a range from about 1.41 to 1.55, while the refractive indices (20°C) for the corresponding linear C 5 -C 14 alkanes cover a range from about 1.36 to about 1.43.Cyclohexane, for example, has a refractive index of approximately 1.43, while hexane has a refractive index of approximately 1.37. A major disadvantage of saturated hydrocarbons is the formation of highly flammable vapor-air mixtures, classified in Temperature Class 3, which specifies a maximum surface temperature of 200 °C for operation in flammable atmospheres. Therefore, when using highly refined mineral oils as coolants, careful and sealed air isolation must be ensured to prevent the formation of such flammable vapor-air mixtures.

[0050] A preferred embodiment of the invention can provide low-viscosity silicone oils as coolants for radiation in the visible and UV spectral range. These oils have refractive indices in the range of approximately 1.37 to 1.40, are advantageously non-flammable, and are transparent from the visible wavelength range up to the mid-UV-C range (approximately 250 nm). Below 250 nm, however, the transmission begins to decrease, and wavelengths shorter than 200 nm are absorbed, so silicone oils are particularly suitable for applications that utilize wavelengths greater than 250 nm. For applications that utilize wavelengths in the range of 200 to 250 nm, silicone oils are only suitable to a limited extent, namely when the path in the emission space between the LED and the emission window, and thus the absorption, is small enough to allow sufficient transmission. Otherwise, saturated hydrocarbons should be used as coolants in the spectral range below 250 nm.

[0051] Further alternative examples of coolants usable according to the invention for radiation in the visible and UV spectral range include synthetic ester and ether compounds. Synthetic organic ester oils have the advantage over mineral oils, among other things, of higher temperature resistance and higher burning and ignition temperatures and are more environmentally friendly, but have lower aging resistance and are transparent up to the mid-UV range (approximately 270 to 280 nm), below which absorption increases significantly. Even with ether compounds such as 1,4-dioxane with a refractive index of 1.422, the transmission extends up to the mid-UV range (270 to 300 nm, except for diethyl ether up to 255 nm), but the transmission decreases less steeply below this, so that if the path between the LED and the emission window is sufficiently short, ether compounds can also be used as coolants for wavelengths below 270 nm.However, wavelengths below 220 nm are absorbed. From a safety perspective, however, it must be considered that ether compounds form highly flammable vapor-air mixtures, with significant differences between the various ether compounds. Diethyl ether, for example, falls under temperature class T4 (maximum permissible surface temperature 135 °C), while 1,4-dioxane falls under temperature class 2 (maximum permissible surface temperature 300 °C), making it more suitable for use as a coolant.

[0052] Depending on the wavelength of the radiation used, fluorinated hydrocarbons such as perfluorocarbons and hydrofluoroethers can also be used as coolants. These are advantageously non-flammable but exhibit absorption bands in certain wavelength ranges. If the radiation used lies outside the absorption bands, fluorinated hydrocarbons such as 3M Fluorinert Electronic Liquid or 3M Novec High-Tech Liquid from 3M™< (3M electronics, St. Paul, USA) can be used. Of course, other liquids can also be used as coolants in a surface radiator according to the invention, as long as they are electrically insulating and transparent to the wavelength of the radiation used.To achieve the required transmission of at least 75% for the desired transparency, the distance between the emission window and the mounting surface with the LEDs can be minimized as much as possible, thus reducing the path through the coolant-filled emission chamber between the LED and the emission window—and thus the absorption of the radiation. At the same time, when dimensioning the emission chamber, the conditions for optimal flow guidance in conjunction with a sufficient liquid volume for optimal heat dissipation must be considered with regard to the distance between the emission window and the mounting surface with the LEDs.

[0053] In a preferred embodiment of the surface radiator 100 according to the invention, the first cooling channel 10 extends through the housing body 1 in such a way that the orifice(s) 13 are formed on a side remote from the inlet opening 3 next to the fastening surface 12, as in Fig. 1 to 10 and 12 to 14can be seen, so that the first cooling channel 10 runs at least partially in a plane parallel to the fastening surface 12 through the housing body 1. In this way, the coolant K flowing through the first cooling channel 10 can already absorb a portion of the heat dissipated by the LEDs 2 via the housing body 1 as it passes through the first cooling channel 10, before the coolant K flows into and through the emission chamber 6 in order to dissipate the majority of the heat from the LEDs 2 through direct contact. The design of the first cooling channel 10 (distance from the fastening surface 12 and route below the fastening surface 12) and an adapted coolant throughput can ensure that a temperature increase of the coolant due to the passage through the first cooling channel 10 is small.The second cooling channel 11 leading to the drain opening 14, through which the coolant K heated by the passage through the emission chamber 6 flows, is kept as short as possible to minimize heat transfer to the housing body 1. Therefore, in the examples shown, the drain opening 14 is formed on a side of the mounting surface 12 close to the return opening 4.

[0054] In the examples of Fig. 1 to 11The respective surface radiator 100 has a first coolant channel 10, which leads from an inlet opening 3 to an outlet opening 13, and a second coolant channel 11, which connects the outlet opening 14 to the return opening 4. This simple embodiment can - depending on the size of the surface radiator 100, i.e. the number and distribution of the LEDs 2 on the mounting surface 12 as well as their line - be entirely sufficient for effective cooling of the LED 2. The outlet opening 13 and the outlet opening 14 are not only arranged on opposite sides of the mounting surface 12, but are also assigned to diagonal corners of the mounting surface 12 in order to flow past as many LEDs 2 as possible as evenly as possible.

[0055] To further equalize the coolant flow through the emission chamber 6, several outlet and drain openings 13, 14 can be provided on the opposite sides of the fastening surface 12, which are arranged evenly distributed along the respective side, as Fig. 12 and 13 The schematic representations are intended only to illustrate the respective principle, but are not to scale and do not represent any restrictions regarding the number and arrangement of the openings, as well as the course and diameter ratios of the channels. Fig. 12illustrates a variant in which the first cooling channel 10 runs through the housing body 1 from the inlet opening 3 to a distribution channel section 10b, which extends in the housing body 1 with respect to the fastening surface 12 along a side that is remote from or facing away from the inlet 3. The distribution channel section 10b is connected to a plurality of outlet openings 13, which are formed on the side remote from the inlet next to the fastening surface 12. On the other side of the fastening surface 12, near the inlet, a corresponding plurality of outlet openings 14 are formed, which are connected via a collecting channel section 11a to the second cooling channel 11, which extends to the return opening 4.

[0056] In a modified variant (not shown), the housing body 1 can have a plurality of parallel first cooling channels 10, each of which extends from a respective associated inlet opening 3 to a correspondingly associated outlet opening 13. Correspondingly, the housing body 1 can have a plurality of second cooling channels 11, each of which extends from a respective associated outlet opening 14 to a respective associated return opening 4. This embodiment is less preferred because a plurality of inlet and return connections for the coolant are required. Nevertheless, a design of the fluid path a with the plurality of cooling channels can be expedient for certain embodiments of the surface radiator 100, depending on the number, arrangement, and power of the LEDs 2 used.

[0057] Fig. 13 shows a design of the fluid path a similar to that in Fig. 12, but with the difference that the distribution channel section 10a is formed here on a side close to the inlet, i.e. far from the mouth opening, with respect to the fastening surface 12, so that a plurality of first cooling channels 10 extend from the distribution channel section 10a through the housing body 1 parallel to the fastening surface 12 to the respectively associated mouth openings 13. With the arrangement of a plurality of first cooling channels 10, which extend below the fastening surface 12 parallel to the mouth openings 13, a more uniform temperature control of the housing body 1 can be achieved, if necessary, as the coolant passes through the first cooling channels than with a single first cooling channel 10 which runs in a straight line on one side below the fastening surface 12.However, a more uniform temperature control can also be achieved with only one cooling channel 10 if this has a course that evenly covers the fastening surface 12, such as the meandering course in . Fig. 14 . While the simpler cooling channel designs of the examples from Fig. 1 to 11 with a maximum of one change of direction of the cooling channel sections through one- or two-sided bores in the housing body 1, the more complex cooling channel designs with more than one change of direction of the channel sections require multi-sided bores with subsequent closures of the bore sections that do not belong to the fluid path, or possibly a generative manufacturing process of the housing body.

[0058] For the fluid-tight arrangement of the emission window 5 on the housing body 1 in order to seal the emission chamber 6 filled with coolant K against the environment, Fig. 1 to 10In the exemplary surface radiator 100 shown, a mounting frame 17 is provided, which in this example is detachably fastened to the housing body 1 by means of screws 50, for which corresponding fastening holes 19 are provided in both the mounting frame 17 and the housing body 1. The mounting frame 17 defines an opening 17a, which in its surface dimensioning essentially corresponds to the fastening surface 12, in order to leave the LED 2 uncovered and to allow the radiation to emerge through the emission window 5. The sealing of the emission chamber 6 is achieved by the arrangement of a circumferential seal 18 between the mounting frame 17 and the emission window 5 and between the emission window 5 and the housing body 1, for which the mounting frame 17 and the housing body 1 each have corresponding sealing grooves 18a (designated in Fig. 6 ) to accommodate a sealing cord or a corresponding sealing element.

[0059] The inventive surface radiator 100 from the example of Fig. 11 Eliminates the need for a mounting frame, as the emission window 5 is secured to the housing body 1 by an adhesive layer 60 and simultaneously sealed. Thus, the surface radiator 100 is designed to be virtually edgeless and thus particularly suitable for seamless installation into a reactor wall element of a device for carrying out a photochemical reaction, for example.

[0060] Of course, variations and combinations of the fastening and sealing of an emission window to a housing body are also conceivable, such as, for example, an emission window being fastened and sealed by an adhesive layer to a support frame which is detachably fastened to the housing body, wherein the arrangement of the support frame to the housing body is sealed by a sealant.

[0061] If a surface emitter according to the invention is intended for use in a device for conducting a photochemical reaction, the sealing of the emission window on the housing body is designed with regard to material selection and shape according to the intended reaction pressures and reaction temperatures that may prevail in the reaction space adjacent to the emission window. This includes, in particular, reaction temperatures and pressures that deviate from room temperature and ambient pressure and that may prevail in the reaction space adjacent to the emission window, and may also include temperatures below +5°C and above +40°C, as well as pressures in the range of high vacuum and 6 bar overpressure.

[0062] How particularly good in Fig. 6As can be seen, the housing body 1 of the exemplary embodiment of a surface radiator 100 according to the invention shown has a first fastening shoulder 12a for arranging the emission window 5 and a second fastening shoulder 12b for arranging the holding frame 17, which stepwise surround the fastening surface 12. The first fastening shoulder 12a is bordered by the step of the second fastening shoulder 12b, wherein the dimensions of the bordered surface correspond to the emission window 5 to be arranged and the height of the step to the second shoulder 12b corresponds to the thickness of the emission window 5. The height of the step of the first fastening shoulder 12a with respect to the fastening surface 12 determines the distance of the emission window 5 from the fastening surface 12 and thus the height of the emission chamber 6, which defines the path for the radiation emitted by the LEDs 2 through the coolant K.The second fastening shoulder 12b for the support frame 17 is also delimited by a border web, wherein the dimensions of the area bordered thereby and the height of the border web correspond to the respective dimensions of the support frame 17 to be arranged.

[0063] The housing body 1 of the example from Fig. 11 ,in which the emission window 5 is attached to the housing body 1 by an adhesive layer 60, has a first attachment shoulder 12a, but without a border by a further attachment shoulder or web, so that the emission window 5 covers the front of the housing body 1. Deviating from the example shown, for the arrangement of an emission window attached by means of an adhesive layer, a border of the first attachment shoulder 12a can also be provided by a further shoulder or web, wherein the dimensions of the area bordered thereby and a height of the border web correspond to the respective dimensions of the emission window.

[0064] To accommodate electrical connection elements for the LEDs 2, the surface radiator 100 according to the invention of the examples from Fig. 1 to 8 and 10on the front side in the housing body 1 adjacent to the fastening surface 12, a connection chamber 15 is formed, open to the emission chamber 5, in the housing body 1 between the first and second cooling channels 10, 11. In the example shown, the connection chamber 15 is concealed by the support frame 17, which for this purpose has a wider frame section on the corresponding side. With the connection chamber 15, a connection opening 16b is formed in the housing body 1 via a passage opening 16a, which allows an electrical connection to a power source. The electrical connection elements, which extend into the connection chamber 15, comprise, in the Fig. 10 shown example connecting cables 22 for connecting the LEDs 2.

[0065] In the exemplary surface radiator 100 shown, the light-emitting semiconductor components 2 are arranged on a circuit board 20, which has corresponding conductor tracks (not shown) for connecting the LEDs 2, which lead to connection contacts 21, which are arranged on a side of the circuit board 20 near the connection chamber 15. A pair of connection contacts 21 is provided for each row of LEDs 2 and is connected to a respective connection line 22. The circuit board 20 can, as in the example of Fig. 1 to 8 be fastened by means of screws 50 to the fastening surface 12 of the housing body 1, which has corresponding fastening holes 19.

[0066] However, the LEDs 2 can, as in Fig. 11As outlined, they can also be attached individually to the mounting surface 12 without a circuit board 20. Each LED 2 can then have its own connection, such a design being particularly suitable for a surface spotlight 100 with a limited number of LEDs or for a surface spotlight 100 in which the LEDs are arranged in a single row, allowing each LED to be connected laterally. In a surface spotlight with multiple rows of LEDs, if a circuit board 20 having conductor tracks for electrically connecting the LEDs is omitted, the mounting surface can, for example, be provided with slots.

[0067] The slots are designed into the mounting surface to allow the connecting cables to the respective LEDs to run through them, preventing any shadows from being cast by the connecting cables. The individual connection of the LEDs, which can thus be controlled individually, means that if one LED fails, only the affected LED needs to be switched off, rather than all of them, allowing the remaining LEDs to continue operating.

[0068] In Fig. 15a) a conventional LED 2 with a plastic lens as the primary optics 2a is shown, which can be used in an LED surface radiator 100 according to the invention. The advantage of flooding with coolant, in contrast to the use of an inert gas such as nitrogen, is that accelerated aging of the primary optics 2a of the LED 2 is avoided, since VOCs ("volatile organic compounds") are present, especially in chemical plants, which penetrate the primary optics 2a, which are usually designed as silicone lenses, cloud them, and thus reduce the luminous efficacy. Since the primary optics 2a are no longer exposed to a gas-containing atmosphere according to the invention, but are shielded by the coolant, the aging process is significantly slowed down.In order to completely avoid the limitations in the light output due to the aging process of the primary optics 2a, in a surface radiator 100 according to the invention there is advantageously the possibility that the LED 2 of the surface radiator 100 completely dispenses with primary optics 2a such as silicone lenses, since the liquid coolant already sufficiently protects the semiconductor chip of the LED from environmental influences and the coolant takes over the functions of the primary optics. Fig. 16 shows a primary optics-free LED 2, the structure of which otherwise consists of semiconductor crystal 2b, wire 2c, anode 2d, LED chip 2e, cathode 2f and base structure 2g or circuit board 20 of the conventional LED 2 from Fig. 15 which, apart from saving a component, further improves the cooling effect.

[0069] In the connection chamber 15, as shown in Fig. 10As can be seen, a ballast 24 for the LEDs 2 can be housed, which is connected to the connecting line 22. Due to the fluid connection of the connection chamber 15 to the emission chamber 6, the connection chamber 15 is also filled with coolant and can dissipate the heat generated by the ballast 24 during operation. This eliminates the need to arrange the ballast 24 on the circuit board 20, thereby preventing heat from being introduced by the ballast 24 via the circuit board 20 to the adjacent LEDs 2. However, arranging a ballast 24 on a circuit board 20 in a surface radiator 100 according to the invention is not excluded, since even in such an embodiment the coolant ensures effective heat dissipation. Furthermore, in an alternative not shown, ballasts such as DC-DC converters or power supplies can be mounted in a housing attachment on the rear of the housing body.Here, too, the liquid coolant can be used to cool the DC-DC converters or other ballasts by connecting the housing attachment to the cooling circuit. For safe operation with ATEX certification, this rear housing attachment can be inerted, flameproofed, or oil-encapsulated. Another alternative, not shown, can provide for the arrangement of the ballast outside the connection chamber and the emission space, so that only the connecting cables 22 are located in the connection chamber 15 and can extend to or through the connection opening 16b. This means that electrical or electronic devices such as DC-DC converters or other ballasts can also be housed in a separate housing near the surface radiator housing body, if necessary.In the event that the surface radiator 100 is operated in an ex-classified zone, the separate housing can then be mounted outside the ex-classified zone.

[0070] A connector plug 23, which is Fig. 10 is connected to the ballast 24, but can alternatively also be connected to connecting lines 22, extends from the connection chamber 15 through the passage opening 16a, whose cross-sectional area is smaller than that of the connection opening 16b, and through the connection opening 16b, so that the electrical connection of the surface radiator 100 can be made from the outside. The connection plug 23 can have a section whose cross-section corresponds to the cross-sectional area of the passage opening 16a, which, as in Fig. 3 can deviate from the circular shape and in the example shown there is formed as a dihedral. Unlike in Fig. 10As shown, a connector plug 23 can have a stepped shape, so that the connector plug 23 not only has a section adapted to the cross-section of the through-opening 16a, but also a section adapted to the cross-section of the connection opening 16b in order to seal the connection chamber 15. Alternatively or additionally, a potting or soldering compound can be used to seal the arrangement of the connector plug 23 in the connection opening 16b and / or in the through-opening 16a in order to prevent leaks through the insulation of the connector plug 23.The same applies to embodiments in which the arrangement is to be sealed with connecting lines 22 or with a cable comprising the connecting lines 22, which extend through the passage opening 16a and the connection opening 16b, in order to prevent leakage of the coolant from the connection chamber 15, so that no coolant can penetrate to the outside through the insulation or the shield of the electrical line due to capillary effects.

[0071] In a similar way, the arrangement of an inlet connection element 30, which is arranged in the inlet opening 3 formed in the housing body 1 and thus provides the inlet connection of the surface radiator 100, and a return connection element 40, which is arranged in the return opening 4 formed in the housing body 1 and thus provides the return connection of the surface radiator 100 (cf. Fig. 1 , 2 , 5 , 7, 8), sealed against leaks using a potting or soldering compound.

[0072] In principle, all connection points can be designed to be fluid-tight in order to prevent coolant from penetrating outside the surface radiator 100 due to capillary effects along the respective connection elements. Measures such as, for example, casting line sections into the housing body and / or plug connections sealed by means of seals can be sufficient for this purpose. Furthermore, all electrical connections that are surrounded by the coolant or come into contact with it can preferably be designed to be fluid-tight in order to prevent the coolant from penetrating, for example, between contact points as a result of creepage and capillary effects due to surface tension, where the electrical contact could be impaired or interrupted under certain circumstances. For plug connections, sealed connectors can be sufficient under certain circumstances, but other measures may also be necessary, e.g.Soldering of the contact points is necessary not only to prevent coolant from creeping but also to ensure electrical contact.

[0073] A surface radiator 100 according to the invention can be used for illumination, for carrying out a photochemical reaction, or for disinfection, depending on the emission spectrum of the LEDs 2 used. Therefore, the arrangement of the inlet opening 3 and the return opening 4 as well as the connection opening 16b on the housing body 1 depends on the installation context of the surface radiator 100 in a corresponding illumination, photochemical reactor, or disinfection device. Thus, the inlet opening 3 and the return opening 4 can be arranged as in the example of Fig. 1 to 10 and 12 to 14 be arranged together on a side surface of the housing body 1. The connection opening 16b can also be arranged, as in the example of Fig. 1 to 8 and 10shown, be arranged on the same side surface as the inlet opening 3 and the return opening 4. The exemplary embodiment of the surface radiator 100 in Fig. 11 shows an arrangement of the inlet opening 3 and the return opening 4 on the rear side of the housing body 1, as in the surface radiator 100 of the device 110 in Fig. 17 , as can be seen from the inlet and return connection elements 30, 40 shown there, which are each connected to an inlet and return opening not shown there. Fig. 17 further shows a connector plug 23, which is arranged in the connection opening (not shown) on the rear side of the housing body 1. However, the inlet, return and connection openings 3, 4, 16b can also be arranged on different sides of the housing body 1, as is the case, for example, with the surface radiator 100 of the Fig. 18illustrated device 110, where an inlet connection element 30, which is connected to an inlet opening not shown there, is arranged on the rear of the housing body 1, while the return connection element 40, which is connected to a return opening not shown there, and the connection plug 23, which is arranged in the connection opening not shown there, are arranged on mutually opposite side surfaces of the housing body 1. However, a device 110 according to the invention is not limited to the arrangement of inlet, return, and connection openings 3, 4, 16b shown in the examples - this can depend on the respective installation context and vary accordingly.

[0074] Because active cooling through direct contact of the LEDs with the coolant allows the use of floodlights with a large number of LEDs, or even their operation at maximum power, a high power density is achieved that can compete with low- and medium-pressure lamps in the field of photochemistry. Managing and controlling the heat balance—thermal management for short—of an LED floodlight, which must also take into account the process temperature of a reaction medium adjacent to the emission window of the floodlight, is crucial for an adequate LED service life.

[0075] Fig. 17illustrates a first example of a device 110 according to the invention, which is designed to carry out a photochemical reaction with a surface radiator 100 according to the invention, whose LEDs 2 provide an emission spectrum for carrying out the photochemical reaction. The device 110 for carrying out a photochemical reaction is a photoreactor, the housing of which comprises a reactor vessel 111 and a reactor lid 112. In the example shown, the installation location provided for the surface radiator 100 is provided in the reactor lid 112 - other reactor devices can also provide installation locations in a wall of the reactor vessel 111. Furthermore, a reactor device 110 can have several installation locations for several surface radiators. For installation in the reactor lid 112, the housing body 1 of the surface radiator 100 has fastening holes 101 (cf. also Fig. 1 and 10 )as built-in elements, so that the surface radiator 100 can be fastened in the reactor cover 112 by means of screws or bolts. In order to achieve optimal cooling of the LEDs 2 here as well, by dissipating heat outside the surface radiator 100, the coolant, which absorbs not only the heat generated by the LEDs 2 but also the heat from exothermic reactions from the reaction chamber adjacent to the emission window 5, is circulated, which leads from the return connection element 40 via a coolant return line 114 in the circuit line 116, which includes a pump and possibly heat exchangers and / or fittings such as valves, etc., for example, to adjust the pressure in the emission chamber, and via a coolant supply line 113 to the inlet connection element 30. Furthermore, the electrical connection of the surface radiator 100 with the connection plug 23 via a connection cable 115 to a power supply and control device 117 is shown.The power supply and control device 117, which may include, for example, ballast or power electronics, drivers - if not housed on the circuit board or in the connection chamber - and power supplies, may be an external power supply and control device.

[0076] At the in Fig. 18 The device 110 shown shows the surface radiator 100 with the inlet and return connection elements 30, 40 as well as the connection plug 23, wherein the device 110 also has a circuit (not shown here) for the coolant from the return connection element 40 via a return, circuit, supply line to the inlet connection element 30 according to Fig. 17 Furthermore, the device 110 can have a power supply for the surface radiator 100, which can be connected to the connector plug 23, for example, via a connecting cable. Fig. 18The exemplary device 110 shown is designed for disinfecting the surface of objects G, wherein the front side of the surface radiator 100 points in the direction of a conveyor belt 118, on which the objects G to be disinfected are conveyed beneath the surface radiator 100, so that the radiation S emitted in the radiation range of the surface radiator 100, which lies in the UV-C spectral range for disinfection, strikes the surfaces of the object G during the conveyance and eliminates germs present there. The installation context of the surface radiator 100 in this device 110 for disinfection comprises a housing, a holder 119, with which the surface radiator 100 is arranged at a predetermined distance above the conveyor belt 118. For this purpose, the surface radiator 100 has fastening holes 101 on the housing body 1 (see also Fig. 1 and 10 )into which pins or screws, for example, can engage for fastening to the bracket 119.

[0077] The type and number of installation elements should not be limited to the illustrated mounting holes, as the type and number of installation elements may also depend on the installation context as well as the size and design of the surface radiator 100. All installation elements can be designed to form a - preferably detachable - plug-in, screw-in, plug-in screw, clamp connection, or similar. Alternative or additional installation elements not shown can be, for example, and not exclusively, pins, tabs, collars, webs, or flanges, or even shaped projections or recesses for engagement with corresponding counter-shaped elements, which can support or simplify the installation of the surface radiator 100 in a device 110.

[0078] The scope of the present invention is not intended to be limited to the two illustrated examples of a device comprising a surface radiator 100 according to the invention.

[0079] A surface radiator according to the invention with improved cooling can be used for any application for illumination, for carrying out a photochemical reaction, or for disinfection using LEDs whose emission spectrum allows for corresponding radiation to be used for illumination, for carrying out a photochemical reaction, or for disinfection. Accordingly, devices for illumination and devices for carrying out a photochemical reaction or for disinfection that differ from the examples shown and that comprise a surface radiator according to the invention are also covered by the scope of protection.

[0080] With regard to the operation of a surface radiator 100 according to the invention with a coolant circulation system in a photoreactor or a device for carrying out a photochemical reaction, care must be taken to keep the flow rate, particularly with silicone oil, low, i.e., preferably below 1 m / s, since otherwise, a non-conductive product present in the photoreactor may become electrostatically charged, with the risk of forming an ignition source. To meet the current requirements for ATEX approval with regard to ignition protection type "o" = oil encapsulation, the coolant must have a kinematic viscosity (at 25°C) of at least 20 cSt, even if coolants with a lower viscosity, for example, 5 cSt, would be technically more advantageous in terms of circulation and maintaining the surface temperatures of the LED.Therefore, the coolant can have a kinematic viscosity (at 25 °C) of 5 to 60 cSt, although, in accordance with applicable explosion protection standards, a viscosity in the range of 20 to 50 cSt is preferred for obtaining appropriate certification. When using high-viscosity coolants, it is also advantageous to dimension the return and supply connection lines with sufficiently large diameters to avoid internal pressure losses and excessive pressure at the LEDs.

[0081] In order to maintain the surface limit temperature of the LEDs, the surface radiator or the higher-level device can, in a further embodiment, additionally have a flow meter for controlling the flow rate of the coolant, since the flow volume of the circulating coolant should not fall below a predetermined minimum value. The flow meter is connected to a control unit configured to control a pump and / or fitting (valve) connected to one of the return and supply connection lines depending on the flow value measured by the flow meter in order to maintain a predetermined flow rate of the coolant through the emission space along a surface of the LED. The control unit can be a separate unit, part of the flow meter, the pump, or the fitting, or part of a control device of the higher-level device.Due to the high viscosity and low flow velocity required for explosion protection, mass flow meters such as Coriolis mass flow meters or variable area flow meters or other suitable measuring methods are preferably used, whereas vortex meters are less suitable. For the high viscosities and low flow velocities required for ATEX certification, Coriolis mass flow meters are particularly suitable as flow meters, as they meet the safety integrity level (SIL) for ATEX approval. However, variable area flow meters can also be used alternatively, providing reliable measurement values at high viscosity and low flow velocity of the coolant. Furthermore, in one of the circuit orA breathing unit with drying agents may be provided in the coolant connection lines, preferably at a highest point, to allow ventilation of the coolant to avoid condensation, whereby the ingress of moisture by fresh air can be prevented by a drying agent such as silica gel.

[0082] To isolate the LEDs from the conditions prevailing in the environment adjacent to the emission window and to avoid impairing the functionality of the LEDs, the emission window can be a double-walled emission window, or the surface radiator or the higher-level device can have a second emission window that covers the emission window delimiting the emission space. The gap formed between the two emission windows or the double walls provides further thermal decoupling. This can be further enhanced by creating a negative pressure in the gap using an extraction device or by connecting an additional cooling circuit for fluid cooling in the gap. In the case of a double-walled emission window design, the gap between the walls can also be evacuated during its manufacture.All liquid or gaseous fluids that are transparent to the radiation used are suitable as cooling fluids, for example water, inert gas such as nitrogen or even air.

[0083] In some embodiments, a surface radiator according to the invention can - depending on the number of LEDs used - have a plurality of circuit boards, each with a partial number of the total LEDs, wherein the circuit boards can be controlled individually. This means that if an LED on a circuit board fails, not all LEDs have to be switched off, but only the affected circuit board, while the other circuit boards can remain in operation. Replacement of the affected circuit board can be postponed to a suitable time, for example after a photochemical reaction carried out with the surface radiator has ended. For this purpose, the surface radiator can have a detection unit for each circuit board, which is configured to detect a failure of one or more LEDs on a circuit board and, depending on a detected failure, to interrupt the power supply to the affected circuit board and, if necessary.to limit the power supply for the other boards accordingly. If necessary, a warning message can also be issued via the control device of the floodlight or the higher-level device if the detection unit is connected to the power supply and control device. In principle, such a detection unit is also conceivable for each LED, so that if individual LEDs fail, the respective power supply is interrupted and the power supply for the other LEDs is limited accordingly, if necessary. This prevents an LED failure accompanied by a temperature hotspot from leading to a chain reaction with the failure of further LEDs due to excessive limit temperatures.

[0084] Furthermore, the surface radiator can have one or more temperature sensors arranged on the housing body or a circuit board and connected to the power supply and control device, which includes a protective switch for LEDs. The protective switch ensures a protective shutdown to protect the semiconductor components if the maximum permissible ambient temperature is exceeded. If the LEDs or LED groups of a surface radiator can be controlled individually, and a temperature sensor is assigned to each LED or LED group, the control device can switch off the LEDs or LED group assigned to that sensor if one of the sensors detects that the maximum temperature has been exceeded. Accordingly, the control device can automatically switch the corresponding LED / LED group back on if the sensor detects that the maximum temperature has been undercut as a result of the protective shutdown.All safety-relevant sensors of the surface radiator, such as the detection units and temperature sensors, can be designed redundantly or with two channels in order to achieve the required SIL class.

[0085] The power supply and control device can further alternatively or additionally comprise at least one control loop for LED control, with which similar or different LEDs can be dimmed and / or the spectrum of the emitted wavelengths of different LEDs can be changed in order to adapt the amount of light emitted or the emitted wavelengths as desired or required. This makes it possible to provide application- or process-specific spectra, wherein the radiation intensity can also be adapted to the application, e.g., a photochemical process, by means of a control loop. For example, in a device for carrying out a photochemical reaction, the power of the LED can be regulated (dimming) for process control, since in many reactions the absorption changes during the process. This can be responded to by targeted measuring and control loops and LED dimming in order to implement an efficient system and avoid over-irradiation.

[0086] A surface emitter according to the invention can comprise monochromatic LEDs as well as a mixture of LEDs with different emission spectra, providing optimal radiation, which, when conducting a photochemical reaction or disinfection, corresponds to optimal utilization of the absorption spectrum of the respective reaction. The same applies if the device for conducting a photochemical reaction is a bioreactor. Here, LEDs with different emission wavelengths can be implemented to achieve optimal growth rates. In different growth phases or for different cells, optimally mixed light spectra and intensities can be used for optimized growth. LIST OF REFERENCE SYMBOLS

[0087] 1 Housing body 2 Light-emitting semiconductor component (LED) 2a, 2b, 2c, Primary optics, semiconductor crystal, wire, 2d, 2e, 2f, 2g Anode, LED chip, cathode, base structure 3 Inlet opening 4 Return opening 5 Emission window 6 Emission chamber 10, 10a, 10b First cooling channel, near-inlet, remote-inlet distribution channel section 11, 11a Second cooling channel, collecting channel section 12 Mounting surface 12a, 12b Mounting shoulder 13 Outlet opening 14 Drain opening 15 Connection chamber 16a, 16b Through-opening, connection opening 17, 17a Supporting frame, opening 18, 18a Seal, sealing groove 19 Mounting hole 20 Circuit board 21 Connection contact pair 22Connecting cable 23Connecting plug 24Driver / ballast 30Inlet connection element 40Return connection element 50Fasteners 60Adhesive layer 100Surface spotlight 101Recessed element 110Lighting device,for carrying out a photochemical reaction or for disinfection 111Reactor vessel 112Reactor lid 113Coolant supply line 114Coolant return line 115Connecting cable 116Circulation line (with pump and, if applicable, heat exchanger) 117Power supply and control device 118Conveyor belt 119Holder aFluid path GTreatment object KElectrically insulating coolant SSurface radiation,

Claims

1. A surface radiator (100), which has at least one light-emitting semiconductor component (2) and a housing body (1), wherein - the housing body (1) has at least one cooling channel (10, 11) for a coolant, which forms at least a part of a fluid path (a), which extends from an inlet opening (3) to a return opening (4), which are formed on the housing body (1), and - an emission window (5), which overlies at least one light-emitting semiconductor component (2) and which defines a front side of the surface radiator (100) and which is transparent for an incident radiation (S), which can be emitted by the semiconductor component (2), is arranged on the housing body (1), and - the housing body (1) provides a fastening surface(12), which is spaced apart from the emission window (5), for the light-emitting semiconductor component (2), wherein the arrangement of the emission window (5) on the housing body (1) is formed in a fluid-tight manner and the housing body (1), the at least one light-emitting semiconductor component (2) and the emission window (5) delimit an emission chamber (6), wherein the fluid path (a) is defined by i) at least one first cooling channel (10), which extends from the inlet opening (3) through the housing body (1) to at least one orifice opening (13), which is formed on a first side adjacent to the fastening surface (12) and ii) the emission chamber (6) from the at least one orifice opening (13) all the way to at least one discharge opening (14), which is formed on a second side facing away from the first side adjacent to the fastening surface (12) and iii) at least one second cooling channel (11), which extends from the discharge opening (14) through the housing body (1) to the return opening (4), wherein the coolant (K) is an electrically insulating liquid, which is transparent for the incident radiation (S), characterized in that a connecting chamber (15), which is open to the emission chamber (5), is formed on the front side in the housing body (1) adjacent to the fastening surface (12), wherein a connecting opening (16b), which is connected to the connecting chamber (15), is formed on the housing body (1), wherein at least one connecting line (22) for connecting the at least one light-emitting semiconductor component (2) extends at least into the connecting chamber (15), wherein - a ballast is provided on a printed circuit board (20), by means of which a plurality of the light-emitting semiconductor components (2) is fastened to the fastening surface (12) and on which a pair of connecting contacts (21) for a row of light-emitting semiconductor components (2) is in each case formed on a side of the printed circuit board (20) close to the connecting chamber (15), wherein each connecting contact (21) is connected to a respective connecting line (22) and the ballast is provided between the connecting contacts (21) and the light-emitting semiconductor components (2) or - a ballast (24) for the at least one light-emitting semiconductor component (2) is arranged in the connecting chamber (15), connected to the at least one connecting line (22).

2. The surface radiator (100) according to claim 1, characterized in that the housing body (1), which is formed for the arrangement of the surface radiator (100) in a device (110) for lighting, for carrying out a photochemical reaction or for disinfection, has a rear side facing away from the front side and is delimited between front side and rear side by means of side surfaces, wherein the inlet opening (3) and the return opening (4) are arranged jointly on one of the side surfaces or the rear side or individually on different side surfaces or on one of the side surfaces and the rear side.

3. The surface radiator (100) according to claim 1 or 2, characterized in that the at least one orifice opening (13) is formed on a side of the fastening surface (12) facing away from the inlet opening (3), wherein the first cooling channel (10) runs through the housing body (1) at least partly in a plane parallel to the fastening surface (12), wherein the at least one discharge opening (14) is preferably formed on a side of the fastening surface (12) close to the return opening (4).

4. The surface radiator (100) according to at least any one of claims 1 to 3, characterized in that - the inlet opening (3) is fluidically connected to a distributor channel section (10a) close to the inlet opening (3), from which several first cooling channels (10) extend to corresponding orifice openings (13) on a side of the fastening surface (12) spaced apart from the inlet opening (3), and the second cooling channel (11) extends from a collecting channel section (11a), which is connected to a plurality of discharge openings (14), to the return opening (4), or - the first cooling channel (10) extends from the inlet opening (3) to a distributor channel section (10b) spaced apart from the inlet opening (3), on which a plurality of orifice openings (13) is formed, and the second cooling channel (11) extends from a collecting channel section (11a), which is connected to a plurality of discharge openings (14), to the return opening (4).

5. The surface radiator (100) according to at least any one of claims 1 to 4, characterized in that - the surface radiator (100) has a holding frame (17), which is arranged on the housing body (1) for holding the emission window (5) and which is formed for leaving the at least one light-emitting semiconductor component (2) uncovered, wherein a respective circumferential seal (18) is arranged between the holding frame (17) and the emission window (5) and between the emission window (5) and the housing body (10), and / or the emission window (5) is fastened to the housing body (1) by means of an adhesive layer (60).

6. The surface radiator (100) according to at least any one of claims 1 to 5, characterized in that on the front side, the housing body (1) has at least one fastening ledge (12a, 12b), which surrounds the fastening surface (12), wherein a first fastening ledge (12a) is formed for receiving the emission window (5) and the distance of the first fastening ledge (12a) from the fastening surface (12) defines a height of the emission chamber (6).

7. The surface radiator (100) according to at least any one of claims 1 to 6, characterized in that the connecting opening (16b) is connected to the connecting chamber (15) via a passage opening (16a), wherein a cross sectional surface of the passage opening (16a) is smaller than a cross sectional surface of the connecting opening (16b).

8. The surface radiator (100) according to at least any one of claims 1 to 7, characterized in that the at least one connecting line (22) extends at least partly into the connecting opening (16b), wherein the arrangement of the at least one connecting line (22) in the connecting opening (16b) is sealed by means of a casting or solder compound, or a connecting plug (23) is connected to the at least one connecting line (22), wherein the connecting plug (23) extends at least partly into the connecting opening (16b), wherein the arrangement of the connecting plug (23) in the connecting opening (16b) is sealed by means of a casting or solder compound.

9. The surface radiator (100) according to at least any one of claims 1 to 8, characterized in that the surface radiator (100) has an inlet connecting element (30), which is connected to the inlet opening (3), and a return connecting element (40), which is connected to the return opening (4), wherein the connection of the inlet connecting element (30) to the inlet opening (3) and / or of the return connecting element (40) to the return opening (4) is sealed by means of a casting or solder compound.

10. A device (110) for lighting, for carrying out a photochemical reaction or for disinfection, which has a surface radiator (100) comprising at least one light-emitting semiconductor component (2), the emission spectrum of which provides a corresponding incident radiation (S) for lighting, for heating, for carrying out a photochemical reaction or for disinfection, characterized in that the surface radiator is a surface radiator (100) according to at least any one of claims 1 to 9.

11. The device (110) according to claim 10, characterized in that the device (110) has a housing (111, 112, 119), which at least partly surrounds a lighting chamber, reaction chamber or disinfection chamber and has at least one installation space for the at least one surface radiator (100), the housing body (1) of which preferably has at least one installation element (101) for the arrangement in the device (110).

12. Use of the surface radiator (100) according to at least any one of claims 1 to 9 for lighting, for carrying out a photochemical reaction or for disinfection, wherein the at least one light-emitting semiconductor component (2) has an emission spectrum, which provides a corresponding incident radiation (S) for lighting, for carrying out a photochemical reaction or for disinfection.