System comprising luminescent material and two-phase cooling device

Abstract

The invention provides a system (1000) comprising (i) a luminescent body (200) and (ii) a two-phase cooling device (400), wherein the two-phase cooling device (400) has a device wall (410), wherein the device wall (410) defines an chamber (450), wherein the device wall (410) comprises a tapering section (405) comprising a contact region (406), wherein the tapering section (405) tapers to the contact region (406), wherein the luminescent 5 body (200) is thermally coupled to the contact region (406), and wherein the device wall (410) has a first thickness d1 at the contact region (406), wherein d1 is selected from the range of 0.15-0.35 mm.

Claims

1. A system comprising (i) a luminescent body and (ii) a two-phase cooling device, wherein the two-phase cooling device has a device wall, wherein the device wall defines a chamber, wherein the device wall comprises a tapering section comprising a contact region, wherein the tapering section tapers to the contact region, wherein the luminescent body is thermally coupled to the contact region, wherein the device wail has a first thickness d.sub.1 at the contact region, wherein d.sub.1 is selected from the range of 0.15-0.35 mm, and wherein the device wall comprises a second section, wherein the tapering section and the second section together define the device wall, and wherein the device wall at the second section has a second thickness d2≥0.4 mm.

2. The system according to claim 1, wherein the system further comprises a light generating device configured to provide light source light to the luminescent body, wherein the luminescent body comprises luminescent material configured to convert at least part of the light source light into luminescent material light.

3. The system according to claim 1, wherein the tapering section tapers to the contact region at a tapering angle α.sub.t selected from the range of 20°-60°.

4. The system according to claim 1, wherein the device wall has a first face and a second face, wherein the first face is directed to the chamber and the second face is directed to the external of the two-phase cooling device, wherein at least part of the first face comprised by the tapering section has a surface roughness ≤120 nm.

5. The system according to claim 1, wherein the device wall comprises a thermally conductive material selected from the group comprising copper, aluminum, stainless steel, nickel, and titanium.

6. The system according to claim 1, wherein the luminescent body has a body thickness d.sub.b perpendicular to a plane defined by the contact region, wherein the body thickness d.sub.b≤2mm.

7. The system according to claim 1, wherein the contact region has a contact area a.sub.c selected from the range of 1-100 mm.sup.2, and wherein the two-phase cooling device has a device axis (A), and wherein the two-phase cooling device has an average cross-sectional area a.sub.m perpendicular to the device axis (A), wherein a.sub.c≤0.7*a.sub.m, and wherein the chamber is hollow.

8. The system according to claim 1, wherein a chamber gas pressure p.sub.c in the chamber is selected from the range of 0.1-0.5 bar, wherein the system comprises a pressure control element, wherein the contact region is exposed to an external air pressure, wherein the pressure control element is configured to control the external air pressure in the range of 0.9*p.sub.c-1.3*p.sub.c.

9. The system according to claim 1, wherein the two-phase cooling device comprises a second contact region arranged opposite of the contact region, wherein the system further comprises a heat exchanger, wherein the second contact region is thermally coupled to the heat exchanger, and wherein the chamber has a volume ≥1 cm.sup.3.

10. The system according to claim 2, wherein the light generating device is thermally coupled to the two-phase cooling device.

11. The system according to claim 2, wherein the system further comprises a control system and a temperature sensor, wherein the temperature sensor is configured to determine a core temperature of the luminescent body and to provide a temperature-related signal to the control system, and wherein the control system is configured to control the core temperature of the luminescent body in the range of ≤200° C. by controlling the light generating device.

12. The system according to claim 1, wherein the two-phase cooling device comprises a heat pipe or a vapor chamber.

13. The system according to any one of the preceding claim 1, wherein the light generating device comprises a laser.

14. A light generating system selected from the group of a lamp, a luminaire, a projector device, a disinfection device, and an optical wireless communication device, comprising the system according to claim 1.

15. The light generating system according to claim 14, wherein the light generating system comprises a plurality of systems, wherein two-phase cooling devices of at least two of the plurality of systems have different first thicknesses d.sub.1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

(2) FIG. 1A-D schematically depict embodiments of the system.

(3) FIG. 2A-D schematically depict results of experimental simulations of embodiments of the system.

(4) FIG. 3A-B schematically depict results of experimental simulations of embodiments of the system.

(5) FIG. 4 schematically depicts embodiments of a light generating system comprising the system. The schematic drawings are not necessarily on scale.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(6) FIG. 1A-D schematically depict embodiments of the system.

(7) FIG. 1A schematically depicts an embodiment of the system 1000 comprising (i) a heat source, especially a luminescent body 200, and (ii) a two-phase cooling device 400. The two-phase cooling device 400 may have a device wall 410. The device wall 410 may define a chamber 450 and may comprise a tapering section 405. The tapering section 405 may comprise a contact region 406 and may taper to the contact region 406. The contact region 406 may be arranged at a first end 401 of the two-phase cooling device 400 along a device axis A, wherein the device axis A may especially be perpendicular to (a plane defined by) the contact region 406. The luminescent body 200 may comprise a luminescent material 210 and may be thermally coupled to the contact region 406, especially such that heat generated by the luminescent body may be transferred to the two-phase cooling device via the contact region 406. At the contact region 406, the device wall 410 may have a first thickness d.sub.1 (along the device axis A), wherein d.sub.1 is selected from the range of 0.10-0.40 mm.

(8) In the depicted embodiment, the luminescent body 200 is depicted in direct (physical) contact with the contact region 406. However, in further embodiments, the luminescent body 200 and the contact region 406 may also be spaced apart by air and/or an interconnect. Hence, in further embodiments the system 1000 may comprise an interconnect, wherein the interconnect is arranged between the luminescent body 200 and the contact region 406. Hence, the interconnect may be thermally coupled to the luminescent body 200 and to the contact region 406.

(9) The chamber 450 may (during operation) comprise a (cooling) liquid 430. The liquid may especially be selected from the group comprising carbon dioxide (≤30° C.), methane (−≤−100° C.), nitrogen (≤−160° C.), acetone (−48° C. to 125° C.), ammonia (−75° C. to 125° C.), ethane, methanol (−75° C. to 120° C.), methylamine (−90° C. to 125° C.), pentane (−125° C. to 125° C.), propylene (−150° C. to 60° C.), water (1° C. to 325° C.), cesium, NaK, potassium, sodium, and lithium, especially one or more of acetone (−48° C. to 125° C.), ammonia (−75° C. to 125° C.), ethane, methanol (−75° C. to 120° C.), methylamine (−90° C. to 125° C.), pentane (−125° C. to 125° C.), propylene (−150° C. to 60° C.), water (1° C. to 325° C.). In further embodiments, the liquid 430 may especially comprise water. Water may be particularly advantageous as it may facilitate transferring a relatively large amount of energy.

(10) In the depicted embodiment, the system 1000 further comprises a light generating device 100, especially a laser-based light generating device 100, configured to provide light source light 101 to the luminescent body 200. In particular, the luminescent body 200, especially the luminescent material 210, may be configured to convert at least part of the light source light 101 into luminescent material light 211. Hence, the system 1000 may provide system light 1001, which may comprise luminescent material light 211 and (optionally) light source light 101.

(11) In embodiments, the two-phase cooling device 400, especially the tapering section 405, may taper to the contact region 406 at a tapering angle α.sub.t. The tapering angle α.sub.t may especially be the (smallest) angle between a plane defined by the tapering section 405 and a plane defined by the second section 420. In particular, the tapering angle α.sub.t may be the (smallest) (average) angle between (i) a plane defined by the tapering section 405 and (ii) the device axis A. The tapering angle α.sub.t may especially be selected from the range of 20°-60°.

(12) In the depicted embodiment, the device wall 410 has a first face 411 and a second face 412, wherein the first face 411 is directed to the chamber 450 and the second face 412 is directed to the external of the two-phase cooling device 400. Especially, (at least part of) the first face 411 comprised by the tapering section 405, especially (at least part of) the first face 411 comprised by the contact region 406, has a surface roughness ≤25 nm.

(13) In further embodiments, the device wall 410 may comprise a second section 420, especially wherein the tapering section 405 and the second section 420 together define the device wall 410. At the second section 420 the device wall 410 may have a second thickness d.sub.2 selected from the range of ≥0.4 mm. In particular, wherein d1/d2≤0.8

(14) In particular, the first face 411 at the tapering section 405 may have a lower surface roughness than the first face 411 at the second section 420.

(15) In embodiments, the chamber 450 may be hollow, i.e., the chamber 450 may be devoid of a wick structure. The chamber 450 may, however, as will be clear to the person skilled in the art, comprise a (cooling) liquid 430, especially during operation.

(16) In the depicted embodiment, the two-phase cooling device 400 comprises a second contact region 426 arranged opposite of the contact region 406, especially at a second end 402 of the two-phase cooling device along the device axis A. The system 1000 may further comprise or be functionally coupled to a heat exchanger 600, especially wherein the second contact region 426 is thermally coupled to the heat exchanger 600. Hence, the two-phase cooling device 400 may transfer heat from the luminescent body 200 to the heat exchanger 600.

(17) In embodiments, the system 1000 may further comprise a control system 300. The control system 300 may be configured to control the system 1000, especially control one or more of the light generating device 100, the heat exchanger 600, and the pressure control element 500, especially the light generating device 100. The control system 300 may be configured to control any aspect of the operation of the controlled elements. In particular, the control system 300 may control the (operational) power of the light generating device 100. Further, the control system 300 may control a thermal transfer capacity of the heat exchanger 600, such as by controlling the amount of a liquid flowing through the heat exchanger 600. In embodiments, the control system 300 may further control the external air pressure provided by the pressure control element 500.

(18) In the depicted embodiment, the system 1000 further comprises a temperature sensor 310. The temperature sensor 310 may be configured to determine a (surface or core) temperature of the luminescent body 200, and especially to provide a temperature-related signal to the control system 300. In such embodiments, the control system may be configured to control the (surface or core) temperature of the luminescent body 200 by controlling the light generating device 100 and/or the heat exchanger, especially the light generating device, or especially the heat exchanger.

(19) FIG. 1B schematically depicts an embodiment of the system 1000, wherein a chamber gas pressure p.sub.c in the chamber 450 is selected from the range of 0.1-0.5 bar. In the depicted embodiment, the system 1000 further comprises a pressure control element 500, wherein the pressure control element 500 is configured to control the external air pressure in the range of 1*p.sub.c-1.2*p.sub.c. In particular, the pressure control element 500 may control the external air pressure the tapering section 405, especially the contact region 406, is exposed to.

(20) In the depicted embodiment, the luminescent body may have a body thickness d.sub.b, especially perpendicular to a plane defined by the contact region, such as parallel to the device axis A, wherein the body thickness d.sub.b≤2 mm, such as ≤1 mm, especially ≤0.8 mm, such as ≤0.6 mm, especially ≤0.5 mm.

(21) FIG. 1C schematically depicts an embodiment of the system 1000, wherein the system comprises a light generating device 100 and an optical element 110, wherein the light generating device 100 is thermally coupled to the two-phase cooling device 1000, especially to the tapering region 405. In further embodiments, the light generating device 100 may be thermally coupled to the contact region 406. In particular, the light generating device 100 is configured to provide light source light 101 to the optical element 110, especially wherein the optical element 110 is configured to redirect the light source light 101 to the luminescent body 200. The optical element 110 may especially comprise focusing optics, more especially reflective focusing optics.

(22) In embodiments, the luminescent body 200 may comprise a luminescent material 210. The luminescent body 200 may especially be configured in a light receiving relationship with the light generating device 100, such as via the optical element 110. The luminescent material 210 may be configured to convert at least part of the (laser) light source light 101, e.g. blue light, into luminescent material light 211, e.g. yellow light.

(23) FIG. 1D schematically depicts an embodiment of the system 1000, wherein the system 1000 comprises two two-phase cooling devices 400 coupled to a single heat exchanger 600. In the depicted embodiment, a first two-phase cooling device 400a is coupled to a single light generating device 100, whereas a second two-phase cooling device 400b is coupled to two light generating devices 100. Hence, the luminescent body 200 of the second two-phase cooling device 400b may be exposed to a larger amount of light source light 101 and may generate more heat. Hence, the second two-phase cooling device 400b may at a second device contact region 406b have a second device first thickness d.sub.1b which is smaller than a first device first thickness d.sub.1a of the first two-phase cooling device 400a at a first device contact region 406a. The smaller thickness may provide a smaller ΔT between opposing sides of the contact region, i.e., T.sub.2b−T.sub.1b<T.sub.2a−T.sub.1a, which may enable the second two-phase cooling device 400b to provide a higher heat transfer than the first two-phase cooling device, despite both two-phase cooling devices 400 being coupled to the same heat exchanger 600.

(24) Hence, in embodiments, the system may comprise two or more two-phase cooling devices 400, wherein at least two of the two or more two-phase cooling devices are thermally coupled to different heat sources, and wherein the at least two of the two or more two-phase cooling devices have different first thicknesses. Systems comprising multiple two-phase cooling devices 400 with different first thickness d.sub.1 may, for example, be beneficial when different heat sources generate varying amounts of heat, or when the (core) temperature of the different heat sources is to be controlled at different temperatures.

(25) FIGS. 2A-D and FIGS. 3A-B schematically depict simulated results corresponding to embodiments of the system 1000. In particular, for the simulations, the device wall 410 comprises copper, which may have a mechanical limit of 258 MPa. However, in general practice, it may be desirable not to push the device wall to its' theoretical limits, and to aim for a lower mechanical stress such as a limit of 210 MPa (used for FIG. 2A-2D) or 180 MPa (used for FIG. 3A-B).

(26) In particular, the simulations were fine element method (FEM) thermal simulations performed with Solidworks. The model was parameterized according to: a luminescent body with a diameter of 3.6 mm; an inner tube diameter (of the two-phase cooling device) of 9.2 mm; a second thickness d.sub.2 of 0.4 mm; a taper length of 7.6 mm (defined along the device axis); a first thickness d.sub.1 in the range of 0.1 mm till 0.4 mm; a device wall comprising copper with a thermal conductivity of 400 W/mK; the second section comprises copper and is functionally coupled to a fixed heat sink temperature of 50° C.; the liquid is water; the chamber has a thermal conductivity of 100.000 W/mK to represent the dual liquid gas stage to mimic the internal two-phase cooling device; the length of the two-phase cooling device (along the device axis) was set at 400 mm.

(27) FIG. 2A-B relate to a system 1000 having a contact region 406 with a first thickness d.sub.1=0.4 mm. FIG. 2C-D relate to a system 1000 having a contact region 406 with a first thickness d.sub.1=0.2 mm. FIG. 2A and FIG. 2C depict the material stress S in MPa imposed on the system 1000, especially imposed on the contact region 406, as a function of the temperature T in ° C. The horizontal line at 210 MPa indicates the selected upper limit for mechanical stress. Hence, for the system 1000 with d.sub.1=0.4 mm, the max temperature may be about 90° C., whereas for the system 1000 with d.sub.1=0.2 mm, the max temperature may be about 80° C. FIG. 2B and FIG. 2D then depict the max power transfer P in W as a function of the temperature T in ° C. Hence, for the system 1000 with d.sub.1=0.4 mm, the max power transfer P may be about 350 W at 80° C. or around 450 W at 90° C., whereas for the system 1000 with d.sub.1=0.2 mm the max power transfer P may be about 650 W at 80° C. Hence, the system 1000 with a lower d.sub.1 may have a lower temperature limit due to mechanical stress, but may facilitate a higher max power transfer P at a given temperature. In particular, the system 1000 with a lower d.sub.1 may have a higher max power transfer P at the respective temperature limits.

(28) FIG. 3A-B schematically depict simulations of the system 1000 wherein the surface temperature of the luminescent body 200 (of the surface directed towards the two-phase cooling device 400) is set at 75° C. In particular, the simulations are performed for a system 1000 comprising a pressure control element 500 configured to provide a pressure difference between the chamber 450 and the external air pressure the contact region 406 is exposed to of 0.1 bar (line L.sub.2) or 0.0 bar (line L.sub.1).

(29) FIG. 3A schematically depicts the mechanical stresses in MPa on the system 1000 as a function of the first thickness d.sub.1. Hence, at each first thickness d.sub.1, the system 1000 operating at a reduced pressure difference may impose a lower mechanical stress on the two-phase cooling device 400, allowing to further reduce d.sub.1 for a given max mechanical stress. In FIG. 3B the max mechanical stress is, for example, set at 180 MPa, in view of the safety factors applied for the material application, as is represented by the horizontal line at 180 MPa. Hence, the embodiment of the system 1000 with the pressure difference of 0.1 has a lower boundary for the first thickness of 0.31 mm, whereas the system 1000 with the pressure difference of 0.0 has a lower boundary for the first thickness of 0.28 mm. FIG. 3B schematically depicts the max power transfer P in W versus the first thickness d.sub.1. As the pressure difference does not directly affect the max power transfer P the lines L.sub.1 and L.sub.2 overlap. The system 1000 operating with a first thickness d.sub.1 of 0.31 mm thus has a max power transfer P of 405 W, whereas the system 1000 operating at a first thickness d.sub.1 of 0.28 mm has a max power transfer P of 440 W. Hence, the pressure control element 500 may be configured to reduce a pressure difference between the chamber 450 and the external air pressure (i.e., external to the two-phase cooling device 400) in order to allow for a two-phase cooling device 400 with a reduced first thickness d.sub.1, which may in turn facilitate a higher max power transfer P.

(30) FIG. 4 schematically depicts embodiments of the light generating system 1200. The light generating system 1200 may especially comprise a lamp 1, a luminaire 2, or projector device 3, comprising the system 1000 as described herein, and providing system light 1001. FIG. 4 schematically depicts an embodiment of a luminaire 2 comprising the system 1000 as described above. Reference 301 indicates a user interface which may be functionally coupled with the control system 300 comprised by or functionally coupled to the system 1000. FIG. 4 also schematically depicts an embodiment of a lamp 1 comprising the system 1000. Reference 3 indicates a projector device 3 or projector system comprising the system 1000, which projector device 3 may be used to project images, such as at a wall.

(31) In further embodiments, the light generating system 1200 may comprises a plurality of systems 1000, especially wherein two-phase cooling devices 400 of (at least) two of the plurality of systems 1000 have different first thicknesses d.sub.1. The two-phase cooling devices 400 with different first thicknesses d.sub.1 may especially be thermally coupled to different (types of) heat sources of the light generating system 1200. Of course, more than two two-phase cooling devices 400 may be available, and two or more of two or more two-phase cooling devices 400 may also in other specific embodiments have the same first thicknesses d.sub.1.

(32) In further A light generating system 1200 selected from the group of a lamp 1, a luminaire 2, a projector device 3, a disinfection device, and an optical wireless communication device, comprising the system 1000 according to any one of the preceding claims.

(33) The term “plurality” refers to two or more. Furthermore, the terms “a plurality of” and “a number of” may be used interchangeably.

(34) The terms “substantially” or “essentially” herein, and similar terms, will be understood by the person skilled in the art. The terms “substantially” or “essentially” may also include embodiments with “entirely”, “completely”, “all”, etc. Hence, in embodiments the adjective substantially or essentially may also be removed. Where applicable, the term “substantially” or the term “essentially” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. Moreover, the terms “about” and “approximately” may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. For numerical values it is to be understood that the terms “substantially”, “essentially”, “about”, and “approximately” may also relate to the range of 90%-110%, such as 95%-105%, especially 99%-101% of the values(s) it refers to.

(35) The term “comprise” also includes embodiments wherein the term “comprises” means “consists of”.

(36) The term “and/or” especially relates to one or more of the items mentioned before and after “and/or”. For instance, a phrase “item 1 and/or item 2” and similar phrases may relate to one or more of item 1 and item 2. The term “comprising” may in an embodiment refer to “consisting of” but may in another embodiment also refer to “containing at least the defined species and optionally one or more other species”.

(37) Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

(38) The devices, apparatus, or systems may herein amongst others be described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation, or devices, apparatus, or systems in operation.

(39) The term “further embodiment” and similar terms may refer to an embodiment comprising the features of the previously discussed embodiment, but may also refer to an alternative embodiment.

(40) It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims.

(41) In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

(42) Use of the verb “to comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, “include”, “including”, “contain”, “containing” and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.

(43) The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim, or an apparatus claim, or a system claim, enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

(44) The invention also provides a control system that may control the device, apparatus, or system, or that may execute the herein described method or process. Yet further, the invention also provides a computer program product, when running on a computer which is functionally coupled to or comprised by the device, apparatus, or system, controls one or more controllable elements of such device, apparatus, or system.

(45) The invention further applies to a device, apparatus, or system comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. Moreover, if a method or an embodiment of the method is described being executed in a device, apparatus, or system, it will be understood that the device, apparatus, or system is suitable for or configured for (executing) the method or the embodiment of the method, respectively.

(46) The various aspects discussed in this patent can be combined in order to provide additional advantages. Further, the person skilled in the art will understand that embodiments can be combined, and that also more than two embodiments can be combined. Furthermore, some of the features can form the basis for one or more divisional applications.