US3604894A - Electrical infrared radiation system - Google Patents

Electrical infrared radiation system Download PDF

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Publication number
US3604894A
US3604894A US731154A US3604894DA US3604894A US 3604894 A US3604894 A US 3604894A US 731154 A US731154 A US 731154A US 3604894D A US3604894D A US 3604894DA US 3604894 A US3604894 A US 3604894A
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Prior art keywords
ridges
assembly
housing
plates
peaks
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Expired - Lifetime
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US731154A
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English (en)
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William G Milligan
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/0014—Devices wherein the heating current flows through particular resistances

Definitions

  • Staubly Attorney-Hill, Sherman, Meroni, Gross & Simpson ABSTRACT A heating assembly of improved efficiency wherein electrically energized heating elements are disposed between the peaks of ridged heat-absorbing and re-radiating surfaces and preferably combined with a convection-reducing wire screen in immediate proximity to the peaks of the surfaces, the angularly disposed ridges and the wire screen cooperating to increase the radiant heat output by a more effective utilization of the heated air and by improved infrared radiation capability.
  • PATENTED SEPI 41971 sum 1 or z INVEN'IUR.
  • One of the most common types of electrical heating elements embodies a metallic sheath in which there is located ahelical coil of electrical resistance wire confined within a compacted mass of magnesia or other heat-insulating material.
  • the bare wire type has even less radiant energy output per watt of input than the tubular type, due to a substantially smaller surface area.
  • electrically energized radiant-heating elements are located in the included angle between a plurality of ridged surfaces.
  • the close proximity of the heating elements to the ridges provides efficient heating of the ridges from the hot air coming off of the heating elements and from the radiant energy given by the heating elements.
  • the effective radiating area is thereby increased, providing for more efficient transmission of heat by infrared radiation.
  • the presence of the wire screen serves to confine the heated air more closely to the vicinity of the radiating surfaces at the base of the notches.
  • the heating elements, the inclined surfaces of the ridged elements, and the I screen interact in a complex manner because of the multiple reflection of the infrared energy between the ridges and the heating elements.
  • FIG. 1 is a cross-sectional view of a heating assembly embodying the improvements of the present invention
  • FIG. 2 is a fragmentary cross-sectional view of the end structure of the assembly shown in FIG. 1;
  • FIG. 3 is an end view of the assembly shown in FIG. 1;
  • FIG. 4 is a cross-sectional view of a modified form of the invention.
  • reference numeral 10 indicates generally a heating assembly including outwardly flared reflector walls 11 and a recessed well portion 12.
  • a thin, heat-reflective sheet such as a piece of aluminum foil 13 lines the bottom of the well portion 12.
  • a body 14 of a heatinsulating material such as a ceramic wool which has low density, high temperature stability, and a very low k factor.
  • Kaowool sold by the name Kaowool. This material is preferably used at a density of about 3 to 8 pounds per cubic foot, and preferably at 4 to 6 pounds per cubic foot.
  • Kaowool One of the particularly preferred types of materials finding use in the present invention is that sold by the name Kaowool. This material is preferably used at a density of about 3 to 8 pounds per cubic foot, and preferably at 4 to 6 pounds per cubic foot.
  • a pair of support brackets 15 and 16 is secured to the housing to confine the body 14 of ceramic wool therein.
  • a ridged metal plate 16 Extending substantially across the full width of the housing is a ridged metal plate 16.
  • the included angle between the peaks of the ridges in the plate 16 is preferably in the range from 50 to for best results. While the ridges in FIG. 1 are shown as having a triangular cross section, for some applications it may be more desirable to use a ridged structure with flattened peaks or even with a pyramidical configuration.
  • the heating elements 17 Disposed between the peaks of the ridges and the plate 16 v are a plurality of electrical heating elements generally indicated at numeral 17 of the drawings. These elements may be of the hairpin type or they may be individual elongated electrical heating elements.
  • the heating elements 17 include an outer metal sheath 18 filled with a compacted mass of magnesia 19 in which there is embedded a helical electrical resistance wire 20. As illustrated, the heating elements 17 are disposed near the base of and in close proximity to the walls of the ridges in the plate 16.
  • a metal screen 21 Disposed in close proximity to the peaks of the ridges of the plate 16 is a metal screen 21 which serves to provide a significant back pressure on the hot air which is heated by the heating elements 17 and reradiates infrared back toward the heating elements.
  • the screen 21 has marginal end portions 22 and 23 which are covered by a mat 24 composed of a ceramic wool material of the type used in the body 14, but preferably of a higher density, say about 8 pounds per cubic foot. As illustrated, the ends of the mat 24 may be folded over about the marginal edges of the plate 16 and over the top of the marginal flange portions 22 and 23. Additional bats of ceramic wool insulation 25 and 26 may be interposed between the marginal flange portions 22 and 23 and the edges of the plate 16.
  • the lateral edges of the plate 16 and the screen 21 are thus freely floating in the ceramic insulation, so that they can better absorb stresses due to expansion and contraction.
  • a pair of pressure plates 27 and 28 are provided as suitable fastening means 29 and 30 to apply confining pressure to the ridges of the screen and the plate.
  • the screen 21 may be made of any suitable metal and preferably has openings in the range from about 4 to per square inch in order to provide the back pressure effect on the gases being heated by the heating element 17. For best results, the screen 21 should be spaced no more than about one-half inch from the tops of the ridges in the plate 16, with onequarter to one-half inch being preferable.
  • the ridged surfaces are preferably constructed of a metal which will both absorb and reemit infrared radiation very efficiently. It is desirable that the ridges absorb as much radiant energy from the radiating elements as possible and pick up as much heat from the heated gases as possible in order to attain a peak efficient radiating temperature. This peak efficiency is obtained when the metal surfaces oxidize and turn very dark, preferably black, over a period of time during normal operation so that they act as very efficient radiant energy emission sources.
  • FIGS 2 and 3 of the drawings The structure of the end of the heating unit is best illustrated in FIGS 2 and 3 of the drawings. As illustrated, there is provided an L-shaped support plate 31 which is welded or otherwise secured to the plate 16. A block 32 of ceramic wool abuts up against the body 14 of ceramic wool, and a portion of the mat 24 of ceramic wool extends between the inner face of the block 32 and the depending leg of the support bracket 31. As best seen in FIG. 3, the block 32 is provided with oversized apertures 33 through which the heating element 17 extends. This type of structure is designed to prevent excessive endwise motion. When the ridges of the plate 16 are heated, normal expansion takes place, and the ceramic fiber insulation is compressed to accommodate the thermal expansion.
  • FIG. 4 of the drawings illustrates a dual arrangement in which two 240-volt element arrays can be used in conjunction with a 480-volt supply.
  • the assembly there shown includes a housing 41 having outwardly inclined baffle walls 42 and 43 and a well 44. Disposed within the well 44 is a divider 45 secured to the base of the well 44 by means of suitable fastening means 46 and 47.
  • the divider 45 separates the assembly into two heating units identical in configuration.
  • the left-hand unit includes a body 48 of relatively low density ceramic wool and a mat 49 of relatively higher density ceramic wool material.
  • a ridged plate 50 rests on the mat 49 and has a marginal flange portion 51 in opposed-spaced relation to a corresponding marginal flange portion 52 of a metal screen 53.
  • the mat 49 is folded over the top of the marginal flange portion 52, and a pad 54 of suitable insulation is interposed between the two marginal flange portions.
  • a plurality of tubular heating elements 57 is received within the notches provided by the ridge surfaces, as in the previous embodiment.
  • a body 61 of ceramic wool and a mat 62 also composed of heat-insulating material.
  • the ridged plate 63 rests on the mat 62 and has a marginal flange portion 64 facing a corresponding marginal flange portion 65 of a screen 66 disposed over the ridged plate 63.
  • a pad 67 of insulation is received between the two opposed marginal flange portions.
  • a pressure plate 68 secured to the baffle wall by means of fastening means 69 serves to apply compressive force against the ceramic wool in which the marginal flange portions 64 and 65 are embedded.
  • the opposite marginal flange portion 71 of the screen 53 and the corresponding marginal flange portion 72 of the screen 66 are also embedded in a mat 73 of ceramic wool, as are opposed marginal flange portions 74 and 75 of the ridged plates 50 and 63, respectively.
  • a fastening means such as a stud 76 extends through the divider 45 and applies a compressive force to hold the marginal flange portions in place while accommodating some lateral movement due to thermal expansion.
  • heating elements designed to operate at 240 volts with a resultant temperature of about 1,500 F. have been observed to achieve temperatures as high as l,700 F., and in some cases even as high as 1,900" F., for the same power input that provides only a l,500 F. temperature when used with a conventional reflector system.
  • the very effective insulation used at the rear of the ridged surfaces reduces the heat loss to the rear such that the housing temperatures at the rear of the assembly are substantially lower than even on air-cooled reflector systems.
  • the reflector and housing temperature of a conventional type of infrared radiating element system has been measured at 375 F., whereas a housing temperature of 200 F. was achieved with the assembly of the present invention utilizing the same heating element at precisely the same power input.
  • the heaters of the present invention were used to dry slowdrying enamel paints which had been applied to A-inch sheet steel. It was found that the paints could be dried to the touch within 15 to 20 minutes by the use of these heaters. In another test, a thin-gauge sheet metal painted with a gloss white baking enamel could be raised in temperature from the ambient temperature of 190 F. in 1 minute, and to 290 F. in 2 minutes. These temperatures were measured at the rear of the metal after the infrared radiation had penetrated the paint film.
  • a plastic material that required 20 minutes to 2 hours of heat-up time in a hot air tunnel at 400 F. could be heated to the point where the plastic material was soft and could be vacuum formed in a matter of seconds. Even transparent material such as a 6-inch sheet of Plexiglas" could be softened sufficiently for vacuum forming in approximately 5 minutes, as contrasted to the normal time of more than 2 hours in a 400 F. hot air kiln.
  • a heating assembly in accordance with the present invention using a single element in the ridges was compared to the results obtained using a single heating element of precisely the same size in conjunction with a reflector. It was found that the assembly of the present invention provided the same radiation output at volts as obtained from the same unit operating at 240 volts in a reflector system.
  • a double heating system of the type shown in FIG. 4 of the drawings having four long tubular rods 56 inches long and placed in a housing 2 feet wide and 53 inches long was used to dry freshly pressed ceramic tile containing approximately 7 A percent moisture. It was found that the tile could be sufficiently dried in l /6 minutes so that a glaze could be sprayed onto the tile.
  • the normal time cycle to accomplish the same results was 6 days of drying in a heated, controlled-humidity room.
  • a heating assembly comprising a housing, a pair of unthe rear of said housing. connected ridged plates supported in said housing, said plates 3.
  • the assembly of claim 1 in which the included angle in being composed of a metal which absorbs infrared radiation the ridges is in the range from 50 to 90. efficiently and which becomes an efficient infrared radiator at 4.
  • the heating assembly of claim 1 in which said plates are the operating temperature of the assembly, an electrical heat- 5 laterally pp r i hin i ng n a m f r mi ing element disposed below the peaks of the ridges in said W001- plates, a wire screen in closely spaced relation to the peaks of
  • the heating assembly of claim 1 which said ridged said ridges, and thermal-insulating means spacing said plates Plates are composed of Stamless sleel' from the re f id h i 6.
  • the heating assembly of claim 1 in which said ridges are four to 100 P P Square f Posltloned with! formed on a plate extending across said housing, and the asabout one'halfmch of the Peaks of Bald sembly includes a mat of ceramic wool spacing said plate from

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  • Resistance Heating (AREA)
US731154A 1968-05-22 1968-05-22 Electrical infrared radiation system Expired - Lifetime US3604894A (en)

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US73115468A 1968-05-22 1968-05-22

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US (1) US3604894A (xx)
JP (1) JPS489773B1 (xx)
BE (1) BE733414A (xx)
DE (1) DE1924143A1 (xx)
ES (1) ES367510A1 (xx)
FR (1) FR2009085A1 (xx)
GB (1) GB1276701A (xx)
IL (1) IL32245A0 (xx)
NL (1) NL6907378A (xx)
OA (1) OA03063A (xx)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4164642A (en) * 1976-12-20 1979-08-14 Ebert Edward A Radiant-hot air heater
US5028760A (en) * 1988-03-15 1991-07-02 Senju Metal Industry, Co., Ltd. Infrared heater

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8922058D0 (en) * 1989-09-29 1989-11-15 T R H Jackson Ltd Electric heater
JP5579521B2 (ja) * 2010-07-22 2014-08-27 中部電力株式会社 高分子材料の熱硬化方法、及び電気加熱炉式の熱硬化装置
DE102015112163A1 (de) * 2015-07-24 2017-01-26 IRES Infrarot Energie Systeme GmbH Wärmestrahler

Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US619314A (en) * 1899-02-14 Electrical heater
US1061332A (en) * 1912-10-28 1913-05-13 George E Sharpe Bath-room heater.
US1399428A (en) * 1920-10-09 1921-12-06 Noel Carrico Electric heater
US1479819A (en) * 1922-02-02 1924-01-08 Anne J Kluever Heater
US1652686A (en) * 1925-04-13 1927-12-13 Magnavox Co Combination radiant and convection heater
US2035306A (en) * 1933-08-30 1936-03-24 Fmc Corp Electric furnace
US2152934A (en) * 1934-06-21 1939-04-04 Harold E Trent Heat transmitting surface
US2469234A (en) * 1945-10-13 1949-05-03 Emerson Electric Mfg Co Fan type heater
US2631216A (en) * 1948-08-13 1953-03-10 Ames Butler Cooking apparatus
FR1078795A (fr) * 1953-06-15 1954-11-23 Dispositif anticonvectionnel pour panneaux et fours infrarouge
US2826669A (en) * 1955-01-05 1958-03-11 William E Schmertz Beam heater
US2879369A (en) * 1955-12-09 1959-03-24 Harold W Huseby Corner radiant heat assembly
US3246121A (en) * 1961-12-29 1966-04-12 Hupp Corp Space heater
US3436524A (en) * 1967-06-05 1969-04-01 Research Inc Heat energy receptor-radiator wall
US3493724A (en) * 1967-08-03 1970-02-03 Harold D Wells Infra-red concentrator

Patent Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US619314A (en) * 1899-02-14 Electrical heater
US1061332A (en) * 1912-10-28 1913-05-13 George E Sharpe Bath-room heater.
US1399428A (en) * 1920-10-09 1921-12-06 Noel Carrico Electric heater
US1479819A (en) * 1922-02-02 1924-01-08 Anne J Kluever Heater
US1652686A (en) * 1925-04-13 1927-12-13 Magnavox Co Combination radiant and convection heater
US2035306A (en) * 1933-08-30 1936-03-24 Fmc Corp Electric furnace
US2152934A (en) * 1934-06-21 1939-04-04 Harold E Trent Heat transmitting surface
US2469234A (en) * 1945-10-13 1949-05-03 Emerson Electric Mfg Co Fan type heater
US2631216A (en) * 1948-08-13 1953-03-10 Ames Butler Cooking apparatus
FR1078795A (fr) * 1953-06-15 1954-11-23 Dispositif anticonvectionnel pour panneaux et fours infrarouge
US2826669A (en) * 1955-01-05 1958-03-11 William E Schmertz Beam heater
US2879369A (en) * 1955-12-09 1959-03-24 Harold W Huseby Corner radiant heat assembly
US3246121A (en) * 1961-12-29 1966-04-12 Hupp Corp Space heater
US3436524A (en) * 1967-06-05 1969-04-01 Research Inc Heat energy receptor-radiator wall
US3493724A (en) * 1967-08-03 1970-02-03 Harold D Wells Infra-red concentrator

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4164642A (en) * 1976-12-20 1979-08-14 Ebert Edward A Radiant-hot air heater
US5028760A (en) * 1988-03-15 1991-07-02 Senju Metal Industry, Co., Ltd. Infrared heater

Also Published As

Publication number Publication date
NL6907378A (xx) 1969-11-25
GB1276701A (en) 1972-06-07
OA03063A (fr) 1970-12-15
FR2009085A1 (xx) 1970-01-30
JPS489773B1 (xx) 1973-03-28
BE733414A (xx) 1969-11-03
ES367510A1 (es) 1971-04-16
DE1924143A1 (de) 1969-11-27
IL32245A0 (en) 1969-07-30

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