Exhaust apparatus, system, and method for enhanced capture and containment

Abstract

A ventilation exhaust intake device is located at ceiling level of a production space and has a low profile form with combination of vertical and horizontal jets. Recesses and other feature are provided to enhance capture and containment and other functional aspects. Certain embodiments include a light source adjacent the jet registers.

Claims

1. An exhaust device, comprising: a housing having an aspect ratio of at least ten; the housing having surfaces defining at least one recess having an exhaust intake; the housing having a perimeter adjacent the at least one recess having a jet register located below the exhaust intake and configured to generate jets, a first of the jets being directed toward the exhaust intake and located below it and a second of the jets being directed substantially vertically downward; lower edges of a portion of the housing containing the exhaust intake and portion of the housing containing the jet register being substantially vertically aligned; the surfaces defining each of the at least one recess forming a piecewise arcuate continuous surface with a light source located adjacent the jet register; the exhaust intake defining a linear horizontal intake area, at least one portion of which is covered by a removable blank; the jet register having directable nozzles forming the first of the jets that are aimed at the exhaust intake areas not covered by the removable blank; the first of the jets terminating at or immediately short of the exhaust intake; the second of the jets terminating above approximately 1.8 meters above a floor level; a control system configured to control at least the volume flow rate of the second of the jets responsively to real time measured draft conditions in a space in which the housing is located; the light source having at least one of a light diffuser, a lamp cover, and a lens and being located adjacent the first jet, the first jet being horizontal, so that the horizontal first jet keeps the light diffuser, lamp cover, or lens clean, whereby the horizontal first jet does double duty by helping to trap fumes by guiding pollution-containing plumes from a fume source and keeping the light source clean; and the light source and an adjacent one of the housing surfaces forming a substantially continuous surface.

2. The device of claim 1, wherein the control system is configured to control the first of the jets responsively to real time measured draft conditions in a space in which the housing is located.

3. The device of claim 1, further comprising a general ventilation register located adjacent the jet register, the general ventilation register directing ventilation air downwardly at non-mixing velocities.

4. The device of claim 1, wherein the jet register surrounds the housing perimeter.

5. The device of claim 1, wherein the first and second of the jets are supplied from a common plenum.

6. The device of claim 1, wherein the first and second of the jets are supplied from separate plenums which are supplied by air sources at separately controlled flow rates.

7. The device of claim 1, wherein the control system includes one or more air velocity sensors indicating a statistic responsive to air movement responsive to the ambient movement of air in said space in which the housing is located, which air movement affects the stability of a rising plume.

8. The device of claim 1, further comprising: a fume source is located below the housing; and an edge of the fume source being positioned to form at least a 20 degree angle from the vertical with the jet register such that all of the fume source lies below the at least one recess.

9. The device of claim 1, further comprising: the first jet being formed from ventilation air or conditioned room air such that the first jet can keep the light cover clean.

10. The exhaust device according to claim 1, wherein the control system is further configured to receive a real time measurement of ambient drafts in the space in which the housing is located, the draft conditions are the measurement of the ambient drafts, and the horizontal first jet keeps the light diffuser, lamp cover, or lens clean by flowing uniformly over an entirety of the light diffuser, lamp cover, or lens.

11. An exhaust device, comprising: a housing having an aspect ratio of at least ten; the housing having surfaces defining at least one recess having an exhaust intake; the housing having a perimeter adjacent the at least one recess having a jet register located below the exhaust intake and configured to generate jets, a first of the jets being directed toward the exhaust intake and located below it and a second of the jets being directed substantially vertically downward; a light source with at least one of a light diffuser, a lamp cover, and a lens located adjacent the jet register; the first jet being formed from ventilation air or conditioned room air such that the first jet can keep the light diffuser, lamp cover, or lens clean by flowing uniformly over an entirety of the light diffuser, lamp cover, or lens; and a control system configured to receive a real time measurement of ambient drafts in a space in which the housing is located and to control at least the volume flow rate of one of the first and second jets responsively to the real time measurement of the ambient drafts.

12. The device of claim 11, wherein lower edges of a portion of the housing containing the exhaust intake and portion of the housing containing the jet register are substantially vertically aligned.

13. The device of claim 11, wherein the surfaces defining each of the at least one recess form a piecewise arcuate continuous surface with a light source located adjacent the jet register.

14. The device of claim 11, wherein the exhaust intake defines a linear horizontal intake area, at least one portion of which is covered by a removable blank.

15. The device of claim 14, wherein the jet register has directable nozzles forming the first of the jets that are aimed at the exhaust intake areas not covered by the removable blank.

16. The device of claim 11, wherein the first of the jets terminates at or immediately short of the exhaust intake.

17. The device of claim 11, wherein the second of the jets terminates above approximately 1.8 meters above a floor level.

18. The device of claim 11, further comprising: a fume source located below the housing; and an edge of the fume source being positioned to form at least a 20 degree angle from the vertical with the jet register such that all of the fume source lies below the at least one recess.

19. The device of claim 11, wherein the control system is configured to control at least the volume flow rate of the second of the jets responsively to real time measured draft conditions in a space in which the housing is located.

20. The device of claim 11, wherein the first jet is horizontal; the horizontal first jet keeps the light diffuser, lamp cover, or lens clean, whereby the horizontal first jet does double duty by helping to trap fumes by guiding pollution-containing plumes from a fume source and keeping the light source clean; the light source and an adjacent one of the housing surfaces form a substantially continuous surface; and the first jet is formed from ventilation air or conditioned room air.

21. An exhaust device, comprising: a housing having an aspect ratio of at least ten; the housing having surfaces defining at least one recess having an exhaust intake; the housing having a perimeter adjacent the at least one recess having a jet register located below the exhaust intake and configured to generate jets, a first of the jets being directed toward the exhaust intake and located below it and a second of the jets being directed substantially vertically downward; lower edges of a portion of the housing containing the exhaust intake and portion of the housing containing the jet register being substantially vertically aligned; the surfaces defining each of the at least one recess forming a piecewise arcuate continuous surface with a light source having a light cover located adjacent the jet register, the first jet being aimed upwardly such that it flows along the recess surface and flows uniformly over an entirety of the light cover, the first jet doing double duty by helping to trap fumes and keep the light cover clean; the first of the jets terminating at or immediately short of the exhaust intake; the second of the jets terminating above approximately 1.8 meters above a floor level; a control system configured to receive a real time measurement of ambient drafts in a space in which the housing is located and to control at least the volume flow rate of one of the first and second jets responsively to the real time measurement; and the light source and an adjacent one of the housing surfaces forming a substantially continuous surface.

22. The device of claim 21, further comprising a general ventilation register located adjacent the jet register, the general ventilation register directing ventilation air downwardly at non-mixing velocities.

23. The device of claim 21, wherein the jet register surrounds the housing perimeter.

24. The device of claim 21, wherein the first and second of the jets are supplied from a common plenum.

25. The device of claim 21, further comprising: a fume source is located below the housing; and an edge of the fume source being positioned to form at least a 20 degree angle from the vertical with the jet register such that all of the fume source lies below the at least one recess.

26. The device of claim 21, further comprising: the first jet being formed from ventilation air or conditioned room air such that the first jet can keep the light cover clean.

27. An exhaust system, comprising: a ventilated ceiling component having surfaces defining multiple recesses each having an exhaust intake; the recesses being distributed over an area of a ceiling; the area having a perimeter adjacent the recesses; the perimeter having: a jet register located below the exhaust intake and configured to generate jets, a first of the jets being directed toward at least one of the exhaust intakes and located below it and a second of the jets being directed substantially vertically downward; the first jet being formed from ventilation air or conditioned room air; and a displacement ventilation register; and a control system configured to receive a real time measurement of ambient drafts in a space in which the housing is located and to control at least the volume flow rate of one of the first and second jets responsively to the real time measurement of the ambient drafts.

28. The system of claim 27, further comprising multiple discharge units located within the area and generating horizontal jets.

29. The device of claim 27, wherein the surfaces defining each of the at least one recess form a piecewise arcuate continuous surface with a light source located adjacent the jet register.

30. The device of claim 27, wherein the exhaust intakes define linear horizontal intake areas, at least one portion of which is covered by a removable blank.

31. The system of claim 27, wherein the jet register and displacement ventilation register are adjacent to each other.

32. The system of claim 27, further comprising: a light source located adjacent the jet register; the light source having at least one of a light diffuser, a lamp cover, and a lens and being located adjacent the first jet, the first jet being horizontal, so that the horizontal first jet keeps the light diffuser, lamp cover, or lens clean, whereby the horizontal first jet does double duty by helping to trap fumes by guiding pollution-containing plumes from a fume source and keeping the light source clean by flowing uniformly over an entirety of the light diffuser, lamp cover, or lens; the light source and an adjacent one of the housing surfaces forming a substantially continuous surface; and the first jet being formed from ventilation air or conditioned room air such that the first jet can keep the light cover clean.

33. An exhaust device, comprising: a housing having an aspect ratio of width to height of at least ten; the housing having surfaces defining at least one recess having an exhaust intake; the housing having a perimeter adjacent the at least one recess having a jet register located below the exhaust intake and configured to simultaneously generate a first jet directed toward the exhaust intake and located below it, and a second jet directed substantially vertically downward; the first jet being formed from ventilation air or conditioned room air; and a control system configured to receive a real time measurement of ambient drafts in a space in which the housing is located and to control one of the first and second jets responsively to the real time measurement of the ambient drafts.

34. The device of claim 33, wherein lower edges of a portion of the housing containing the exhaust intake and of a portion of the housing containing the jet register are substantially vertically aligned.

35. The device of claim 33, wherein the surfaces defining each of the at least one recess form a piecewise arcuate continuous surface with a light source located adjacent the jet register.

36. The device of claim 33, wherein the exhaust intake defines a linear horizontal intake area, at least one portion of which is covered by a removable blank.

37. The device of claim 36, wherein the jet register has at least one directable nozzle forming the first jet, which is aimed at the exhaust intake area not covered by the removable blank.

38. The device of claim 33, wherein the first jet terminates at or immediately short of the exhaust intake.

39. The device of claim 33, further comprising: a fume source located below the housing; and an edge of the fume source being positioned such that a line from the fume source edge to the jet register forms at least a 20 degree angle from vertical, and such that all of the fume source lies below the at least one recess.

40. The device of claim 33, wherein the control system is configured to control at least the volume flow rate of the second jet responsively to real time measured draft conditions in the space in which the housing is located.

41. The device of claim 33, wherein the control system is configured to control at least the volume flow rate of the first jet responsively to real time measured draft conditions in the space in which the housing is located.

42. The device of claim 33, further comprising a general ventilation register located adjacent the jet register, the general ventilation register directing ventilation air downwardly at non-mixing velocities.

43. The device of claim 33, wherein the jet register surrounds the housing perimeter.

44. The device of claim 33, wherein the first and second jets are supplied from a common plenum.

45. The device of claim 33, wherein the first and second jets are supplied from separate plenums, which are supplied by air sources at separately controlled flow rates.

46. The device of claim 33, where the recess depth is more than five times a distance between a blind end of the recess and the fume source.

47. The device of claim 33 where the recess depth is more than eight times a distance between a blind end of the recess and the fume source.

48. The device of claim 33, further comprising: a light source located adjacent the jet register; the light source having at least one of a light diffuser, a lamp cover, and a lens and being located adjacent the first jet, the first jet being horizontal, so that the horizontal first jet keeps the light diffuser, lamp cover, or lens clean, whereby the horizontal first jet does double duty by helping to trap fumes by guiding pollution-containing plumes from a fume source and keeping the light source clean; the light source and an adjacent one of the housing surfaces forming a substantially continuous surface; and the first jet being formed from ventilation air or conditioned room air such that the first jet can keep the light cover clean by flowing uniformly over an entirety of the light diffuser, lamp cover, or lens.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate exemplary embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain the features of the invention.

(2) FIG. 1 illustrates a side/section view of a lighting ventilation device (LVD) and fume source in a conditioned space.

(3) FIGS. 2A and 2B illustrate the LVD of FIG. 1 in section and bottom views.

(4) FIG. 3 illustrate another embodiment of an LVD.

(5) FIGS. 4A and 4B illustrate a portion of a horizontal and vertical jet register according to an embodiment.

(6) FIG. 4C illustrates a portion of a horizontal and vertical jet register according to another embodiment.

(7) FIG. 4D illustrates a section view of an LVD in which the horizontal jet originates from a position that is not below the intake, in which there is no light fixture and in which the jet register is configured in accord with the embodiment of FIG. 4C, all of which are features that may be combined or substituted for any and all of the corresponding features of the other embodiments.

(8) FIG. 5 illustrates features of a control system.

(9) FIG. 6 illustrates an LVD with vertical and horizontal jets surrounding it on multiple sides.

(10) FIGS. 7A, 7B, and 7C illustrate an aimable horizontal jet nozzle.

(11) FIG. 8 shows various combinations of elements ventilation elements combined in kitchen ventilation system.

DESCRIPTION OF EMBODIMENTS

(12) The efficiency of exhaust systems that employ ventilated ceiling systems, where the exhaust intake is located at the ceiling level, is particularly challenging. The capture efficiency of the system must be assured to prevent the spreading of impurities throughout the conditioned space. It has been shown that the efficiency of the exhaust system can be improved with a horizontal jet near the ceiling surface. The air jet is projected horizontally across the ceiling, which helps to direct heat and air impurities towards the exhaust intake. Preferably, such jets have a volume flow rate that is only about 10% of the total supply air flow rate. In the ventilated ceiling, the jet may improve the total effectiveness of the ventilation system. With the horizontal jet, the average contaminant level in the occupied zone was shown to be 40% lower than one without and the estimated energy saving potential can be as high as 23%.

(13) A ventilated ceiling may have features similar to the devices shown in D407473, filed 1 Apr. 1999 and shown and described in U.S. Pat. No. 5,312,296, filed 30 Jan. 1991, both of which are hereby incorporated herein. In an embodiment, the ventilation device of U.S. Pat. No. 5,312,296 is modified by including a vertical curtain jet register between the non-mixing ventilation register 17 and the horizontal jet register 15. The vertical curtain jet register in this embodiment has a velocity, thickness and breadth as to form a continuous curtain jet that terminates at about the height of the head of a worker, or approximately 1.8 m above the floor when located in an interior space. In another embodiment, the device is modified by lifting the intake plenum 18 and dropping the ventilation registers such that a configuration similar to that of FIG. 1 is formed. Preferably, in this embodiment, a recess as indicated at 108 in FIG. 1 may be defined. The recess 108 may have one or more arching surfaces as indicated in FIG. 1 at 109.

(14) Referring now to FIG. 1, which shows a preferred embodiment of a lighting-ventilation device (LVD) 10. A general ventilation register 132 receives air from a plenum 134 which may be supplied through a collar 104 shared with another plenum 136 or through a separate collar (not shown). The register 132 is preferably configured such that ventilation air, cooler than the ambient below the register, is provided at non-mixing velocities as is typical for displacement ventilation applications. The general ventilation register 132 may or may not be present. It may be on one side of the device 10, as shown, or on two or three sides, or it may completely encircle the LVD 10.

(15) An additional combined vertical and horizontal jet register 138 emits air so as to form substantially vertical and substantially horizontal jets as indicated by arrows 122 and 120, respectively. The vertical and horizontal jets may be supplied via a plenum 136 (supplied through a collar 104) and may encircle, flank on two or three sides, or border on a single side, the LVD 10. The vertical and horizontal jets may be supplied by ventilation air, ambient air, or conditioned room air. Each may also be supplied from different ones of these sources of air. Preferably, the velocity of the horizontal jet 120 is such that it terminates approximately at the point where it would otherwise reach an exhaust intake 114, which preferably has a removable filter 113. Exhausted fumes and air are removed via plenums 106 and exhaust collars 102 which attach to suitable ductwork. Notwithstanding the name, horizontal, the angle of the horizontal jet 120 may be aimed toward the center of the exhaust intake 114 or at some intermediate angle between such angle and the horizontal.

(16) Unlike the device of U.S. Pat. No. 5,312,296, in the embodiment of FIG. 1, the intakes are relatively lowered and the origin of the horizontal jet register is lowered such as to form a low profile configuration with two recesses 108. This configuration has the benefit of placing the horizontal jet below the intake while retaining the low profile and pleasing appearance of a ventilated ceiling as illustrated US D407473. It also creates a shallow recess 108. Preferably diffusers or windows 111 are located in a surface 109 the recess 108 with lamps 110, for example fluorescent lamps located behind them such as to form a continuous that a smooth surface 109. Lights and diffusers 140 and 141 may also be located at a center between recesses 108. Note that in an alternative embodiment, only one of the horizontal 120 and vertical 122 jets are provided in combination with the configuration illustrated having the recess and the intake 114 located above the point where the jet register 138.

(17) Preferably, the vertical and horizontal jets 122, 120 originate from approximately the same location (register 138) which coincides with a perimeter of the LVD 10. They do not need to be supplied from the same source of air nor do they need to originate from a common register structure. It is preferable, however that they both are positioned to form a 20 angle from the vertical and whose vertex is at the outermost edge of the pollution-generating part 121 of an appliance 100. Thus, lower appliances must be located more inwardly and higher appliances can be located more outwardly. This minimum angle may be reduced if the exhaust flow is increased or the jet flow rates are increased.

(18) Preferably the horizontal jet has a velocity of 6 to 10 m/s and a volume flow rate per linear meter of 21 to 35 cm/hr per linear meter of the LVD 10 perimeter for a typical kitchen application. These approximately coincide with the throw conditions identified above. Preferably, the total volume rate of the vertical jets to the total volume rate of the horizontal jets is preferably about 0.25 to 0.35. These are not necessarily required values, but are representative for kitchen applications. A preferred aspect ratio of the exhaust device (e.g., W/Y indicated in FIG. 3) is greater than ten.

(19) FIGS. 2A and 2B illustrate the LVD in section 2A and plan view (as viewed from underneath) 2B. Blanks 118 are fitted to portions of the intake lengths to prevent air and fumes from being drawn into portions 139 of the LVD. The blanks 118 may replace removable filter cartridges (not shown, but for example, impact-type grease filters or as shown in U.S. Pat. No. 4,872,892, filed 16 Sep. 1988). The blanks 118 permit the exhaust to be drawn in positions overlying the pollution sources. Preferably, they are used only over areas with no pollutions sources and permit an overhang of the open intakes 114 over each pollution source of at least 20 degrees as discussed above with reference to the overhang angle of FIG. 1.

(20) Referring to FIG. 3, as discussed above, a horizontal jet may be provided which is aimed nearly horizontally as indicated at 201, slightly upwardly toward the center of the intake 210, as indicated at 202, or even more upwardly as indicated at 203 such that it flows along the recess 217 surface 215. A combination of these jets may be employed. In the embodiment of FIG. 3, a light diffuser, lamp cover, or lens 214 is located adjacent horizontal jet to help keep it clean such that the horizontal jet does double duty by helping to trap fumes (guide pollution-containing plumes) and keep the light cover 214 clean. A vertical jet 218 may also be provided. FIG. 3 also illustrates an embodiment with a recess 217 and which has the horizontal jet outlet located below the intake, but in which there is only one intake 210 connected to a common plenum 216 for each recess 217 on one side rather than two as in the prior embodiments. In an alternative embodiment, only one intake 210 and one recess 217 are provided in a configuration in which, preferably, a wall 237 bounds the intake side of the LVD 223.

(21) FIGS. 4A and 4B show a configuration for a common vertical and horizontal register fed from a plenum 250. FIG. 4A shows a section view and 4B shows a bottom view. A hole 238 generates the vertical jet 228. A nozzle 231 generates the horizontal jet 230. The nozzle 231 may be forged with the illustrated shape and an opening in a flat sheet of metal 240, which forms the shell of the plenum 250, at regular intervals. Examples of dimensions are shown. The opening 232 of the nozzle 231 may be 3.5 mm deep and 12 mm wide. The hole 238 may be 4.5 mm in diameter. The spacing between the jets/holes may be 30 mm. These dimensions are illustrative only. FIG. 4C shows in section another configuration of a jet register fed through a plenum 252 defined in a box-shaped extension 242. A hole 236 generates the vertical jet 228. Another hole 234 in the side of the box shaped extension 242 generates the horizontal jet 230. The holes may be formed at regular intervals along the register. Examples of dimensions are shown. The opening 234 may be 6.5 mm in diameter. The hole 236 may be 4.5 mm in diameter. The spacing between the jets/holes may be 30 mm. These dimensions are illustrative only.

(22) FIG. 4D illustrates a section view of an LVD 293 in which the horizontal jet 290 originates from a position that is not below the intake 292, in which there is no light fixture and in which the jet register 296 is configured in accord with the embodiment of FIG. 4C, all of which are features that may be combined or substituted for any and all of the corresponding features of the other embodiments. The LVD 293 contains a recess 294 defined within the jet register 296 which is substantially aligned with the bottom of the exhaust intake 292. A vertical jet 291 emanates from the jet register 296.

(23) FIG. 5 shows a control system that may be used in connection with the embodiments. Sensors (which may include associate signal conditioning and data processing elements) 310 may include one or more of: air velocity sensors indicating the average or maximum velocities (or some other statistic) responsive to the movement of air in the conditioned space, which air movement affects the stability of a rising plume, such as drafts, air movement induced by movement of personnel, etc. identified as ambient drafts 310a; activity level sensors 310b responsive to the movement in the conditioned space that may cause air movement that can disrupt the plume including information extracted from event recognition in a video stream, activity from a proximity or infrared distance detector or range finder; time of day 310c from which the activity level may be inferred, such as in a production workspace such as a commercial kitchen; fume load 310d which may be indicated by means of a fuel usage indicator of a heat source such as a range or grill, a carbon dioxide detector, a temperature or moisture sensor or other composition sensor which may indicate the composition of a fume plume, a video stream-based event recognition device, for example one configured to recognize zero, light, medium, and heavy use of an appliance and the nature of the use; and temperatures 310e such as indoor, outdoor, and plume temperatures.

(24) A controller 302 receives one or more sensor 310 signals and may control one or more outputs including drives 304-308 which control flow rates indicated by fan symbols 312-316. The drives 304-308 may be damper drives or speed drives or any device for controlling volume flow rate. The drive signals may control the exhaust rate, vertical jet flow rate, horizontal jet flow rate, and/or displacement ventilation flow rate. Any of these may be controlled separately or together (e.g., a common drive signal or a mechanical coupling in the control and mechanical aspects) according to various mechanical embodiments (such as one in which a shared plenum provides air for both the vertical and horizontal jets).

(25) In an embodiment, the exhaust flow rate is preferably modulated responsively to the fume load and/or indicators of drafts or air movement in the conditioned space. The velocities of the vertical and/or horizontal jets may be modulated in response to such inputs as well. For example, when there is greater air movement in the conditioned space, such as caused by workers moving about, the exhaust velocity may be proportionately increased and the vertical jet speed may be increased proportionately as well.

(26) FIG. 6 shows a perspective illustration of a configuration in which the vertical 311 and horizontal 312 jets run along an entire perimeter of a LVD 10. FIGS. 7A, 7B, and 7C illustrate an aimable horizontal jet nozzle 350. The nozzle 350, which may be a press-fitted plastic member. When a section of the LVD is fitted with blanks and therefore has zones without exhaust intakes, the aligned portions of horizontal and vertical jet registers may be tilted to direct certain ones 376 at a horizontal angle toward an adjacent intake section 370 and away from a section with a blank 372 as shown in FIG. 7C. For long blank sections 372, some of the horizontal jet outlets may be closed or plugged. The holes for the vertical jets 356 are also shown. Tilted positions 354 are shown. Any of the nozzles may also be substituted with a discharge vent with a movable vane and/or sliding damper blade.

(27) While the present invention has been disclosed with reference to certain embodiments, numerous modifications, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the present invention, as defined in the appended claims. Accordingly, it is intended that the present invention not be limited to the described embodiments, but that it has the full scope defined by the language of the following claims, and equivalents thereof.

(28) Although the LVDs shown including lighting components, these are not essential to all embodiments and any of the embodiment may be modified by their removal. The LVD structures may be configured as modular components that can be assembled to form various shapes to cover pollution sources in various arrangements in a production space. Blanks that cover exhaust intakes may be provided as part of a kit and used to redefine the exhaust intake coverage as a production space is modified by the replacement, removal, or rearrangement of pollutions sources. Control adjustments discussed above may be done manually as well as automatically. The LVD embodiments may be surface mounted or recessed into a ceiling or false ceiling. General ventilation registers may be located at all sides of an LVD or only some sides. General ventilation registers may be located adjacent or remotely from the LVD. Note also that although the vertical and horizontal jets in the embodiments described are single point jets forming linear arrays, in alternative embodiments, the jets may be formed as slots to form vertical and horizontal curtains.

(29) FIG. 8 shows various combinations of elements ventilation elements combined in kitchen ventilation system. Multiple recesses such as indicated at 860 cover an entire ceiling area of a kitchen thereby protecting multiple appliances 816 which can be located anywhere in the kitchen. The region covered by the multiple recesses 860 can have any number sections producing horizontal 807 and vertical 808 jets and makeup air discharges 810, such as indicated at 823. Each recess may have an exhaust inlet 846 drawing fumes as indicated at 802 thereinto. The horizontal jets can be located at various locations throughout the multiple recesses to help direct fumes to the exhaust and away from other ceiling fixtures such as the lights 804. The vertical jets 808 are preferably located to define the perimeter of the protected are. Alternatively the perimeter can be defined by a displacement ventilation register 830 or a wall (not shown).

(30) In the present and all systems, a ventilated ceiling is distinguished from conventional hoods by being very shallow relative to the height at which it is located. Here in this case, the depth 842 of the recess 860 may be more than five time the distance 840 from the source of fumes and the blind end of the recess 860.

(31) Note that any of the embodiments described herein may be modified by eliminating the lighting component. So wherever the term LVD is used, the alternative lacking a light source is also a possible embodiment.