ALL WEATHER ELECTRIC INDOOR/OUTDOOR HEAT EXCHANGER FACE MASK

Abstract

A face mask apparatus is formed with a breathing chamber that provides adjustable warm and humidified air for inhalation. The breathing chamber heats cold air that is breathed in through the face mask during normal breathing, which is worn over the nose and mouth of a person. A temperature gauge monitors temperature for future adjustment of the amount of heat generating current. The air in the chamber is heated for inhalation by a resistive carbon fiber tape. The temperature of the resistive material (and by extension the warm air generated), is regulated/adjusted by increasing or decreasing the current output settings on the power source. Warm and humidified air is produced. The face mask may be part of a balaclava hood or a hat, or to other head gear, or as a stand-alone with straps around the head, optionally with an adjustable solar powered battery.

Claims

1. A cold weather face mask for conditioning air to be breathed comprising: a facial covering housing adapted for covering the nose and mouth of a user; said housing having a front opening; a valve member removably fitted into said front opening, said valve member having openings for incoming and exhaled air, a concave shaped inner frame within said housing nested in said valve member enclosing a minimally restrictive breathing chamber for allowing mingling of incoming and exhaled air, said inner frame having an opening to accommodate said valve member openings allowing otherwise minimally unrestricted flow of both said incoming and exhaled air through said face mask; means within said minimally restrictive breathing chamber for heating said mingled incoming and exhaled air whereby turbulence of mixed inhaled colder air and exhaled warmer and moister air allows a user to inhale heated and humidified air; said heating means comprising a strip of heat generating conductive resistive material mounted on a surface of a support bar extending through said breathing chamber from one side of said inner frame to an another side of said frame; whereby inspired unrestricted and unimpeded cold air is heated in said minimally restrictive breathing chamber and goes directly in the mouth and nose of the user; and a source of energy for said heating means.

2. The face mask of claim 1 in which said strip of heat generating material is adhesively bonded to said surface of said support bar.

3. The face mask of claim 2 in which said strip of heat generating material is a carbon fiber tape and said energy is electricity.

4. The face mask of claim 3 in which said support bar extends through said breathing chamber with an edge of the heat generating material provided in cross section facing air flow.

5. The face mask as in claim 2 wherein said at least one rigid support bar extends horizontally half way up said inner frame and said strip of heat generating material attaches thereto with the width of the heat generating material provided in the cross section of the air flow.

6. The face mask as in claim 3 wherein said support bar extends horizontally half way up said inner frame.

7. The face mask as in claim 2 wherein said at least one rigid support bar is a vertically extending support bar attached at the apex and the base of the inner frame, said support bar supporting a strip of heat generating material for attachment thereto with the width of the heat generating material in the cross section of the air flow.

8. The face mask as in claim 2 wherein said at least one rigid support bar is a vertically extending support bar attached at the apex and the base of the inner frame, said support bar supporting a strip of heat generating material for attachment thereto with the edge of the heat generating material in the cross section of the air flow.

9. The face mask as in claim 2 wherein said at least one rigid support bar is a cantilevered horizontally extending support bar attached at the apex and the base of the inner frame, said support bar supporting a strip of heat generating material for attachment thereto with the width of the heat generating material in the cross section of the air flow.

2. The face mask as in claim 2 wherein said at least one rigid support bar is a cantilevered vertically extending support bar attached at the apex and the base of the inner frame, said support bar supporting a strip of heat generating material for attachment thereto with the edge of the heat generating material in the cross section of the air flow.

11. The face mask as in claim 2 wherein said at least one rigid support bar is an angled support bar attached at the apex and the base of the inner frame, said support bar supporting a strip of heat generating material for attachment thereto with the width of the heat generating material in the cross section of the air flow.

12. The face mask as in claim 2 wherein said at least one rigid support bar is an arcuate support bar attached at the apex and the base of the inner frame, said support bar supporting a strip of heat generating material for attachment thereto with the width of the heat generating material in the cross section of the air flow.

13. The face mask as in claim 2 at least one rigid support bar to support said carbon fiber tape within said breathing chamber for improving heat transfer is a plurality of rigid support bars, each supporting a portion of said strip of heat generating material thereon.

14. The face mask of claim 1 in which said support bar extends vertically through said breathing chamber.

15. The face mask of claim 1 wherein said mixed inhaled colder air and exhaled warmer and moister air is heated to a temperature in the range of about 40 to 95 deg. F.

16. The face mask of claim 1 in which said breathing chamber has weep holes for draining condensate.

17. The face mask of claim 1 in which said source of energy is a battery.

18. The face mask of claim 17 having means on said face mask to adjust the amount of electric current delivered to said conductive resistive material.

19. The face mask of claim 17 having means for thermostatically controlling the heating of air mixture within said breathing chamber.

20. A method of heating and moisturizing breathing air within a face mask comprising the steps of: placing a mask on the face of a user, said mask comprising a housing covering the nose and mouth of said user, said housing having a front opening. inserting into said front opening a valve member removably fitted thereinto, said valve member having openings for incoming and exhaled air, and having a concave shaped inner frame nested in said valve member enclosing a minimally restrictive breathing chambers, said inner frame having an opening to accommodate said valve member openings allowing otherwise unrestricted flow of both said incoming and exhaled air through said face mask; heating mingled incoming and exhaled air within said minimally restrictive breathing chamber whereby turbulence of mixed inhaled colder air and exhaled warmer and moister air allows a user to inhale heated and humidified air; using controllable heating means comprising a strip of heat generating conductive resistive material mounted on a surface of a support bar extending through said breathing chamber from one side of said inner frame to another side of said inner frame for heating said mingled air; whereby inspired unrestricted and unimpeded cold air is heated in said minimally restrictive breathing chamber and goes directly in the mouth and nose of the user; and providing a source of electric energy for said heating means.

21. The method of claim 20 in which said support bar extends vertically through said breathing chamber.

22. The method of claim 20 wherein said mixed inhaled colder air and exhaled warmer and moister air is heated to a temperature in the range of about 40 to 95 deg. F.

23. The method of claim 20 in which said breathing chamber has weep holes for draining condensate.

24. The method of claim 20 in which said support bar extends horizontally through said breathing chamber for radiating heat inwardly.

25. The method of claim 20 in which said strip of heat generating material is a carbon fiber tape.

26. The method of claim 20 in which said source of electricity is a battery.

27. The method of claim 26 in which electric current delivered to said strip of heat generating material is adjustable.

28. The method of claim 24 in which said support bar is oriented so that a side edge of said strip of heat generating material attached thereto faces said air flow.

29. The method of claim 16 wherein said at least one rigid support bar is a plurality of support bars.

30. The method of claim 20 in which the heating of air mixture within said breathing chamber is thermostatically controlled.

31. The method of claim 20 wherein an orientation of said support bar is movable within said minimally restrictive breathing chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The present invention can best be understood in connection with the accompanying drawings. It is noted that the invention is not limited to the precise embodiments shown in the following drawings, in which:

[0070] FIG. 1 is a front perspective view of a user wearing a heat exchanger (HE) face mask of this invention.

[0071] FIG. 2 is a top perspective view of the HE face mask of this invention.

[0072] FIG. 3 is a partial exploded view of the face mask of this invention with a full inlet plate.

[0073] FIG. 4 is a perspective view of a three quarters inlet plate.

[0074] FIG. 5 is a perspective view of a half inlet plate.

[0075] FIG. 6 is a perspective view of quarter inlet plate.

[0076] FIG. 7 is an enlarged detail of the tape/weave/cable connection.

[0077] FIG. 8 is a perspective view of heat chamber section with a horseshoe shaped heat tape element.

[0078] FIG. 9 is a detail of the heat tape attachment and silicone coating on the inner chamber wall.

[0079] FIG. 10 is a perspective/exploded view of the HE face mask of this invention showing more details of components and placement.

[0080] FIG. 11 is a side view cross section of the heat chamber.

[0081] FIG. 12 is a front perspective view in partial cutaway of a user wearing a HE face mask with an open front, with part of the user's hidden face shown exposed.

[0082] FIG. 13 is a front perspective view of a user wearing a HE face mask with a closed balaclava head covering, showing only the eyes exposed to the environment.

[0083] FIG. 14 is a front perspective view of a HE face mask worn over a neck gator.

[0084] FIG. 15 is a front perspective view of an alternate embodiment showing a stand-alone mask including a nasal/mouth covering only, held on the head of the user by one or more skull encircling straps.

[0085] FIG. 16 is a perspective view of a man in a wheelchair using a HE face mask in an indoor venue.

[0086] FIG. 17 is a schematic block diagram of a circuit to support the operational aspects of the face mask of this invention.

[0087] FIG. 18 is a schematic diagram of a simplified HE face mask embodiment with a factory set internal operating temperature.

[0088] FIG. 19 is a schematic diagram of an even more simplified embodiment of a face mask without a thermostatic element.

[0089] FIGS. 20-27 are perspective/exploded views of the HE face mask with a variety of shapes, locations, and orientations of the heating elements.

[0090] FIG. 20 shows a horizontal support bar halfway up inner frame supporting a rectangular heating element for attachment thereto with the width of the heating element in the cross section of the air flow.

[0091] FIG. 21 shows a horizontal support bar halfway up inner frame supporting a rectangular heating element for attachment thereto with the edge of the heating element in the cross section of the air flow.

[0092] FIG. 22 shows a vertical support bar attached at the apex and the base of the inner frame supporting a rectangular heating element for attachment thereto with the width of the heating element in the cross section of the air flow.

[0093] FIG. 23 shows a vertical support bar attached at the apex and base of the inner frame supporting a rectangular heating element thereto with the edge of the heating element in the cross section of the air flow.

[0094] FIG. 24 shows a horizontal support bar cantilevered from one side of the inner frame halfway up the inner frame supporting a rectangular heating element for attachment thereto with the edge of the heating element in the cross section of the air low.

[0095] FIG. 25 shows a support bar attached at the base of the inner frame at a slight angle from the vertical supporting a rectangular heating element for attachment thereto with the edge of the heating element in the cross section of the air flow.

[0096] FIG. 26 shows a bent support bar with a horizontal section attached to one side of the inner frame, a slightly obtuse angle at the bend and the lower distal end attached at the base of the inner frame. A heating element with two rectangular sections is attached to the support bar legs with the edge of the heating element in the cross section of the air flow.

[0097] FIG. 27 shows an arcuate support bar attached at one side of the inner frame and at the bottom of the inner frame. A heating element bent in the arcuate bar shape is attached such that the edge is in the cross section of the air flow.

DETAILED DESCRIPTION OF THE INVENTION

[0098] Applicant's face mask apparatus (or “face mask”) 1, which is constructed according to the inventive principles, presents with a similar view in profile to the aforementioned N95 face mask, known in the prior art. See FIGS. 1-3 for a breathing chamber that is shaped by an inner frame 9 (which is preferably concave) having both an interior and exterior surface. An outer surface of the inner frame 9 is attached to an inner surface of the facial covering 2. The physical dimensions of the inner frame 9 define the physical dimensions of the breathing chamber. A resistive carbon fiber tape 7 is installed in the inner frame within the breathing chamber. Preferably, there are weep holes 21 on the bottom of the inner frame 9 and/or the facial covering to drain moisture, i.e., condensation precipitated when cold air taken into the breathing chamber from the outside meets the warm, moisture-laden air exhaled by the user into the inner air volume 4 of the breathing chamber. The weep hole(s) control(s) moisture content of the air to be breathed. The inner frame 9, or breathing chamber structural housing, is preferably manufactured out of medical grade polyurethane, medical grade neoprene®, medical grade silicone, or other medical grade polymers. The preferred material is medical grade polyurethane or medical grade Neoprene®. The material comprising the inner frame 9 may be the same material as the facial covering or a combination of the disclosed materials. The material comprising the facial covering 2 may be any material, such as natural and man-made cloths, leather, processed paper, etc., as known to one of ordinary skill in the art, for making medical and non-medical face masks. The heated face mask includes a relatively shallow nasal/mouth breathing chamber, without awkward and unwieldly protuberance nasal/mouth breathing chambers.

[0099] A preferred method of use of the inventive face mask is with a scarf or Balaclava, so that the face mask apparatus beds down nicely on the Balaclava or scarf material. For that matter, a proximal edge of the walls of the breathing chamber (i.e., formed by inner frame 9), and/or the facial covering, except to the portion with the hole or opening 4, rests in a flush with the user's face. Preferably, the edge is quasi airtight. The Balaclava or scarf material is preferred to affix a battery or solar battery, that is electrically connected to an electric element (for example, resistive carbon fiber tape), as will be explained in greater detail below.

[0100] It is notable that the weight of the inner frame 9 installed in the mask 1 is preferably less than one (1) ounce due to the light weight nature of the resistive carbon fiber tape 7 that is relied upon for heating and otherwise conditioning the air to be breathed. Preferably, the aggregate weight of the battery 25 and carbon fiber tape 7 is less than 4 ounces. An optional larger battery 27 for the face mask apparatus 1 may be placed in a shirt pocket, purse, scarf, neck warmer, balaclava and the like. The face mask apparatus 1, plus the electrically resistive carbon fiber tape members 7, within the face mask 1 is very light weight. It is remarkable how the face mask 1, being so small, unobtrusive, and lightweight, can do so much. In fact, there is no way of visually seeing the electrically resistive carbon fiber tape 7, or tapes, is/are installed in the face mask 1 from the outside (preferably in the inner frame 9), except for the thin wires leading away from the resistive carbon fiber tape, out of the mask. The battery may be installed on the mask itself, or in a garment proximate the mask.

[0101] As shown in FIG. 3, on the front of the face mask apparatus 1 is an inlet plate or valve 5 that connects to the inner frame and covers breathing hole or opening 4 of the inner frame 9. The inlet plate or valve 5 is formed with vertical slots, or horizontal slots, or both, that is turned to define air intake resistance for air intake and air exhalation. This inlet plate or valve 5 affixes to the breathing chamber 9 or housing with a snap or bayonet mount, to affix to the inner frame 9 or housing, or reverse twist to remove. The inlet plate or valve 5 is interchangeable with other inlet plates/valves 11 (see FIG. 4), 13 (see FIG. 5) or 15 (see FIG. 6) with different slits for different levels of air intake and exhalation, i.e. for air resistance training of athletes.

[0102] The face mask 1 of the present invention can be used for both heated air and humidity, and by switching inlet plate or valve 5, 11, 13 or 15, for air resistance training, all rolled up into one unit. There may be an additional inlet plate, valve, or filter plate (not shown) with a filter for particulates as an option, or a combination of an inlet plate or valve with slit and a filter. The entire inlet plate or valve 5, 11, 13 or 15 may be removed for competitive athletic events.

[0103] Without being limited, held, or bound to any particular theory or mechanism of action of the invention, it is thought that the electric current supplied to the carbon fiber tape or tapes 7 heats the lightweight tape, which heats the air within the breathing chamber formed by inner frame 9. When a person inhales the cold or cool air is heated and humidified in the breathing chamber by the turbulence of the mixing of hot and cold air, then the warm and humidified air is inhaled fully to the lungs. The nose and passages there are also warmed and humidified.

[0104] The Interior of the applicant's face mask is shown in exploded views of FIGS. 8, 10 and 11, looking down at the inner frame 9 (and breathing chamber) from inside the face mask 1.

[0105] The electrically resistive carbon fiber tape 7 used is a resistive material which, when a current is applied, generates heat. FIG. 10 shows the installation of the resistive carbon fiber tape 7 in a crescent horseshoe manner. The horseshoe shape for the electrically resistive carbon fiber tape 7 is the preferred shape within the breathing chamber. The carbon fiber tape 7 is affixed to the interior (e.g., inner surface) of the inner frame 9 with silicone rubber, rubber cement, epoxy, or other adhesive agents. As shown in the close-up detail view of FIG. 9, a light brush coat of silicone rubber or other sealant is applied over the carbon fiber tape member 7. As shown in FIG. 7, two separate wires affixed to the carbon fiber tape 7 on opposite sides of the tape 7, extend from within the breathing chamber 9 (defined by the contour of inner frame 9 when its proximal edges contact the person's face/head) to outside the inner frame 9, to the lithium ion 7.4V battery, lithium ion 5V battery, lithium ion 3.7V battery, or any known battery 25 with sufficient current to warm the resistive carbon fiber material of carbon fiber tape member 7, or to a solar cell 59 with an attached battery, as shown in the electrical schematic diagram FIG. 17.

[0106] The preferred resistive material is an electrically resistive carbon fiber tape 7, viscose based, also used as a biocompatible material used for wound healing and human body implants. It feels like fine silk. It is safe. As importantly, it is substantially light weight to minimize the obtrusiveness of wearing a face mask. There is a long-established history with this resistive carbon fiber tape 7 for electric heated clothing, including knee wrap, gloves, sleeping bag, heated gloves, heated beanie, heated insoles, heated modular vest, etc. See the prior art documents of “You can do it”, see DIY carbon heated gloves for visualizations of the tape in gloves. See the prior art “Carbon tape Tips”, for how to cut, solder, join, coat tape with silicone rubber, etc. See also the prior art document “About carbon fiber tape & carbon fiber rope”. In an alternative embodiment, electrically conductive carbon fiber rope can also be used but is not preferred.

[0107] There are other resistive materials which can be used, which, when a current is applied thereto, generate heat. This includes the metals copper, silver, alloys, resistive conductive Fabric, See prior art Econ Tex®, and many more.

[0108] It is possible to monitor and adjust the breathing chamber temperature with a smart phone, or remote computer, and adjust the current output of the battery with a smart phone or computer. To do so, the face mask includes a controller and a means for communicating between the controller in the face mask and the smart phone, so that the controller can transmit and receive instructions required to control the temperature and/or humidity in the chamber. Preferably, a resistive element is included in the electrical pathway between the battery and the resistive carbon fiber tape to control the amount of electrical energy used to drive or otherwise heat the tape 7. The resistor is adjustable and limits the current thereby. Such remote control enables a user to conveniently raise or lower the temperature and/or humidity of the air in the breathing chamber. The “Warming Store” sells remote control for battery-heated gloves. In the schematic diagram of FIG. 17, a thermometer with a temperature readout 29 can be provided on the inventive face mask 1 and is connected with a Wi-Fi transmitter 66 to the smart phone. Optionally the humidity inside the chamber formed by the inner frame 9 also can be monitored and transmitted to a smart phone.

[0109] To summarize, the FIGS. 1-19 are reviewed below in greater detail. In FIG. 1, heat exchanger (HE) face mask 1 is shown being worn; in FIG. 2 a top view is shown with a small solar panel 3 installed.

[0110] FIG. 3 shows the inner frame 9 with the resistive carbon fiber tape 7 separated for clarity with full inlet plate or valve 5 separated from the front. The face mask includes the resistive carbon fiber tape 7, which is provided in a width of between about 1/64 inch and about 2 and ½ inch wide.

[0111] FIGS. 4, 5, and 6 show more restrictive inlet plates or valves 11, 13 and 15 respectively which may be used for athletic training.

[0112] FIG. 8 illustrates an inner frame 9 with different resistive carbon fiber tape 7 shapes within: horseshoe, crescent or curved u-shaped. Also weep holes 21 are illustrated in FIGS. 8 and 11. FIG. 7 is a detail showing the wiring pigtail at the end of conductive carbon fiber 7 and the return weave 17 conductor terminating in plug 19. FIG. 9 is a detail showing a coated tape 23 which is adhered, and brush coated with silicone to the inner heat chamber wall.

[0113] FIG. 12 is an exploded view of heat and moisture exchange (HME) face mask 1 illustrating some features not previously shown in FIG. 3. Small on-mask battery 25 is visible near zipper compartment 31 where it would normally reside. On/off switch 23 and temperature readout 29 are also shown with temperature adjustment set point potentiometer 35. A larger battery 27 which can be carried in a breast pocket is also shown. Medicine access port 43 is shown on the side of the housing.

[0114] FIG. 11 is a cross section of the inner frame 9 showing the intake air flow through inner volume 4 between face plate 5 and the nose and mouth of the user.

[0115] FIG. 12 shows a user using mask 1 as part of a balaclava headgear 37, with a partial open front exposing the eyes. Part of the mask 1 with face covering 2 is shown in cutaway. FIG. 13 shows a user with the balaclava headgear 37 of FIG. 12, with the balaclava headgear closed around mask 1. FIG. 14 shows mask 1 being used over neck gator scarf 39. FIG. 15 shows an alternate embodiment of a stand-alone mask 1 including a nasal/mouth covering 2 only, held on the head of the user by one or more skull encircling straps. This simplified embodiment enables the user to wear conventional head gear and street clothes, without the excessive covering of a balaclava headgear only exposing the user's eyes.

[0116] FIG. 16 shows a person with a compromised respiratory system, such as COPD, for example, in wheelchair 41 using mask 1 in an indoor area.

[0117] FIG. 17 is an electrical diagram showing one possible implementation of heat exchanger (HE) face mask 1. Power is derived from small attached battery 25, or a remote battery plugged in at connector 53. Solar panel 59 is wired so as to power the face mask apparatus via steering diodes 56 and 57. Steering diode 55 protects remote battery. Power switch 33 controls operation on/off but does not interrupt charging of battery 25 by either solar panel 39 or a remote charger plugged in at connector 51. Heat tape 7 (if segmented, all segments in series) is driven by adjustable voltage regulator 67 which is regulated by microprocessor 65 which is continuously running a thermostat loop involving digital thermometer 63 with temperature read-out 29. The set point for the temperature setting is either the physical setting of potentiometer 35 or a remote input from a cell phone or computer via Wi-Fi (or Bluetooth) as per user choice. Fixed voltage regulator 61 is used to power microprocessor 65, digital thermometer 63 and set pot 35. If only remote setting of temperature is desired, potentiometer 35 can be eliminated, but the manual option provides redundancy in case of communications problems.

[0118] FIG. 18 shows a schematic diagram of a more simplified embodiment without temperature adjustability. Through testing in the proper cold environment, a factory-installed bimetal thermostat switch 69 of the appropriate rating is selected. This component behaves like a switch which is normally closed below the switching temperature and opens and stays open if the temperature is at or above the switching temperature. In operation it will automatically open and close keeping resistive carbon fiber tape 7 within a narrow range of the switching temperature. This component 69 should be snugged between resistive carbon fiber tape 7 and the wall of inner frame 9 forming the breathing chamber 9. The other two components of the circuit are battery 25 and on/off switch 33.

[0119] FIG. 19 is a further simplification with no thermostatic element. resistive carbon fiber tape 7 is directly connected to a battery holder 71 which removably holds battery 25 and provides on/off switch 72 which is part of battery holder 71. The temperature of resistive carbon fiber tape 7 is wholly regulated by the condition of battery 25.

[0120] While any kind of suitable battery may be useful for heating the electrically resistive carbon fiber tape segments 7, a preferred example is a Gerbing Gyde 7V 7000 mAh extended-life rechargeable battery with a remote and charger kit, and action heat 5V and 3.7V rechargeable lithium ion batteries.

[0121] The schematic diagrams of FIGS. 17, 18 and 19 can be used for any mask of this invention from FIG. 1 through FIG. 27.

[0122] Although the preferred embodiment location of heating element 7 is as shown in FIG. 10, around the inside of the opening of inner frame 9, other locations and orientations are possible. The FIGS. 20-27 explore these other embodiments which do obstruct the air flow a minimal amount. In these figures, a new element, the support bar (9a), is introduced. Support bar 9a is a rigid anchorage for heating element 7 to which it is attached as by adhesive bonding. Aluminum, plastic, or other material can be used. In FIG. 20, support bar 9a is attached horizontally halfway up the opening in inner frame 9. Heating element 7 is attached to it across the opening with the width perpendicular to the air flow. This causes turbulence and improves heat transfer from element 7 to air flow at the expense of some obstruction. In FIG. 21 a horizontal placement is used with edge of support 9a with attached heating element 7 intrudes into the air flow with more impingement and better heat transfer than the FIG. 10 embodiment. In FIG. 22, a vertical placement of support 9a and a longer element 7 cause more turbulence in the air flow by virtue of the width orientation of element 7 in the air flow for even better heat transfer than in FIG. 21 with accompanied increased flow obstruction. The vertical orientation of heating element 7 in FIG. 23 also permits a longer element 7. However, the orientation of the width of element 7 parallel to the air flow helps reduce obstruction. FIG. 24 attaches heating element 7 to support 9a which is cantilevered from one side of frame 9; the air flow should be similar to that of FIG. 21. FIG. 25 shows a slightly angled support bar 9a attached to the bottom of inner frame 9 in a cantilever fashion. The width of heater element 7 is oriented parallel to the air flow and its length is shorter than that of FIG. 23 so the obstruction should be less than that introduced in FIG. 23. The 2-part heating element 7 of FIG. 26 distinguishes it from the one-part elements of the previous embodiments. Element 7 is attached to angle support bar 9a with attachments to inner frame 9 at one wall and bottom. Placing heating element 7 more squarely in the air flow than the original FIG. 10 configuration aids heat transfer without adding much obstruction as the edge is parallel to the air flow. FIG. 27 shows an arcuate variation of the FIG. 26 embodiment using an arcuate (or flexible) heating element 7 with equivalent performance.

[0123] It is also noted that the support bars can be a plurality of support bars of varying configurations and orientations supporting heating elements 7 thereon.

[0124] In the foregoing description, certain terms and visual depictions are used to illustrate the preferred embodiment. However, no unnecessary limitations are to be construed by the terms used or illustrations depicted, beyond what is shown in the prior art, since the terms and illustrations are exemplary only, and are not meant to limit the scope of the present invention.

[0125] It is further known that other modifications may be made to the present invention, without departing the scope of the invention, as noted in the appended Claims.