EP0082627A1 - An improved fluid permeable porous electric heating element - Google Patents
An improved fluid permeable porous electric heating element Download PDFInfo
- Publication number
- EP0082627A1 EP0082627A1 EP82306494A EP82306494A EP0082627A1 EP 0082627 A1 EP0082627 A1 EP 0082627A1 EP 82306494 A EP82306494 A EP 82306494A EP 82306494 A EP82306494 A EP 82306494A EP 0082627 A1 EP0082627 A1 EP 0082627A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- coating
- precursor
- heating
- heating element
- temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- 239000012530 fluid Substances 0.000 title claims abstract description 27
- 238000005485 electric heating Methods 0.000 title claims abstract description 20
- 238000010438 heat treatment Methods 0.000 claims abstract description 137
- 238000000576 coating method Methods 0.000 claims abstract description 82
- 239000011248 coating agent Substances 0.000 claims abstract description 69
- 239000000463 material Substances 0.000 claims abstract description 37
- 239000002243 precursor Substances 0.000 claims abstract description 35
- 238000000034 method Methods 0.000 claims description 40
- 239000007789 gas Substances 0.000 claims description 37
- 230000008569 process Effects 0.000 claims description 36
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 24
- 229910052799 carbon Inorganic materials 0.000 claims description 22
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 21
- 229910052710 silicon Inorganic materials 0.000 claims description 21
- 239000010703 silicon Substances 0.000 claims description 21
- 230000003647 oxidation Effects 0.000 claims description 14
- 238000007254 oxidation reaction Methods 0.000 claims description 14
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 12
- 238000003763 carbonization Methods 0.000 claims description 10
- 239000002019 doping agent Substances 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- 230000000717 retained effect Effects 0.000 claims description 6
- 239000011810 insulating material Substances 0.000 claims description 4
- 239000004411 aluminium Substances 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 3
- 239000001301 oxygen Substances 0.000 claims description 3
- 229910052760 oxygen Inorganic materials 0.000 claims description 3
- 238000000354 decomposition reaction Methods 0.000 claims description 2
- 239000000126 substance Substances 0.000 claims description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims 1
- 239000007833 carbon precursor Substances 0.000 description 34
- 239000003921 oil Substances 0.000 description 22
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 15
- 229910010271 silicon carbide Inorganic materials 0.000 description 15
- 239000000203 mixture Substances 0.000 description 13
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 8
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 8
- 229910052802 copper Inorganic materials 0.000 description 8
- 239000010949 copper Substances 0.000 description 8
- XYFCBTPGUUZFHI-UHFFFAOYSA-N Phosphine Chemical compound P XYFCBTPGUUZFHI-UHFFFAOYSA-N 0.000 description 6
- 238000001816 cooling Methods 0.000 description 6
- BHEPBYXIRTUNPN-UHFFFAOYSA-N hydridophosphorus(.) (triplet) Chemical compound [PH] BHEPBYXIRTUNPN-UHFFFAOYSA-N 0.000 description 6
- 239000012212 insulator Substances 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 230000004044 response Effects 0.000 description 6
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 5
- 229910000077 silane Inorganic materials 0.000 description 5
- 229910001220 stainless steel Inorganic materials 0.000 description 5
- 239000010935 stainless steel Substances 0.000 description 5
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 4
- 239000005977 Ethylene Substances 0.000 description 4
- 239000004952 Polyamide Substances 0.000 description 4
- 229910052786 argon Inorganic materials 0.000 description 4
- 229910052785 arsenic Inorganic materials 0.000 description 4
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 229920002647 polyamide Polymers 0.000 description 4
- 239000000377 silicon dioxide Substances 0.000 description 4
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 3
- 229910052796 boron Inorganic materials 0.000 description 3
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 238000000151 deposition Methods 0.000 description 3
- 230000008021 deposition Effects 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229910000073 phosphorus hydride Inorganic materials 0.000 description 3
- 239000004033 plastic Substances 0.000 description 3
- 229920003023 plastic Polymers 0.000 description 3
- 239000000376 reactant Substances 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- 229910052581 Si3N4 Inorganic materials 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 238000000429 assembly Methods 0.000 description 2
- 230000000712 assembly Effects 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 238000005137 deposition process Methods 0.000 description 2
- YBMRDBCBODYGJE-UHFFFAOYSA-N germanium dioxide Chemical compound O=[Ge]=O YBMRDBCBODYGJE-UHFFFAOYSA-N 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 230000002706 hydrostatic effect Effects 0.000 description 2
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910001369 Brass Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000005234 chemical deposition Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 239000013529 heat transfer fluid Substances 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000010849 ion bombardment Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000000615 nonconductor Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 125000006850 spacer group Chemical group 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
- F24H1/10—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium
- F24H1/101—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium using electric energy supply
- F24H1/102—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium using electric energy supply with resistance
- F24H1/103—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium using electric energy supply with resistance with bare resistances in direct contact with the fluid
-
- 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
- H05B3/10—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor
- H05B3/12—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material
- H05B3/14—Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor characterised by the composition or nature of the conductive material the material being non-metallic
- H05B3/148—Silicon, e.g. silicon carbide, magnesium silicide, heating transistors or diodes
Definitions
- the invention in a first aspect provides a process for manufacturing a fluid permeable, fibrous electric heating element, the process comprising forming a permeable fibrous precursor, coating fibres of the precursor with a material so as to form tubular fibres comprising the material, and heating the coated precursor so as to modify the structure of the material to provide a desired electrical resistivity of the tubular fibres.
- porous electric heating elements are described in British Patent Specification Nos 1466240 (United States Patent No 3943330), 1503644, and 1600253 (United States Patent No 4257157), these Specifications and Patents being incorporated by reference herein.
- the system components include a circulating pump, a heating element assembly, valves and pipework with the oil passing in series through the element and the mould, die, extruder, or calender to be heated together with a control system.
- 'Such units have been devised and operated at heating element power ratings in the range 1 - 30 kW for the aforementioned heating element geometry and with a response time of a few seconds.
- Very compact units can be designed and for the high power units, the small size which is attainable by the use of a high heating element power density rating reduces the cost of construction considerably compared with conventional heat transfer systems.
- the permeable element electric heating unit 14 is generally of circular form in transverse section, and comprises a fluid permeable fibrous heating element 30 of hollow cylindrical form, for example 120 mm long, and having gold plated copper electrodes 31 and 32 at the upper and at the lower ends of the heating element 30 respectively.
- the lower electrode 32 is joined to a brass end cap 34 that is joined to a steel tube 33 brazed to a copper rod 35 which is connected by a clamp-type terminal 36 to an electric supply (not shown).
- a shorter heating element 30 may be used in the heating unit 14, to overcome the problem of non-uniform flow which arises with long heating elements 30 as a result of hydrostatic pressure differences along the heating element 30, and to increase the fluid velocity through the heating element 30 so that a high power generation density may be employed.
- An example of such a compact heating element is shown in Figure 4 in which an electric heating unit 14a incorporates a fluid permeable fibrous heating element 80 of hollow cylindrical form and typically about 45 mm outside diameter, 35 mm inside diameter, and 10 mm long.
- Gold plated annular copper electrodes 81 and 82 are disposed at respective ends of the heating element 80, and each electrode 81, 82 is supported on a boss 83, 84 from a respective stainless steel annular backing disc 85 or 86.
- Each electrode assembly 146, 147 provides a pressure tight, electric feedthrough from respective electric supply cables 150, 151 to respective copper braid electrical connections 152, 153 each terminating at a respective copper terminal member 155, 156 secured as shown in Figure 4a to a shoulder 157 of the respective electrode 81 or 82.
- Suitable such electrode assemblies 146, 147 may be obtained for example from VG Electronics Limited, Hastings, London, England, or Ferranti Limited, Hollinwood, Lancashire, England, or Friedrichsfeld GmbH, Mannheim, West Germany, (United Kingdom Agents: Bush Beach Engineering Limited, Cheadle, Cheshire, England).
- the porous electric heating element may be made from a precursor in the form of a permeable fibrous carbon electric heating element comprising carbon fibres, made for example as described in the aforementioned patent Specifications, and coated with material conveniently applied by a plasma assisted deposition process (hereinafter referred to as P A VD).
- P A VD plasma assisted deposition process
- the electrical properties of this deposited material, which may be modified after deposition by appropriate heat treatments may largely determine the electrical operating characteristics of the porous electric heating element.
- the permeable fibrous carbon precursor on which the material is deposited by the PAVD process may be retained, or may be removed from beneath the deposited material by means of an oxidation process.
- a plasma is used as a medium for chemical reaction, and deposition of a coating on a substrate is achieved through the decomposition of a gas in an electrically-induced plasma.
- An example of the plasma assisted deposition process is described in British Patent Specification No 2056829A, and related techniques are disclosed in the paper "Codeposition of Glassy Silica and Germania inside a Tube by Plasma Activated CVD" by D. Kuppers et al, Journal of the Electrochemical Society Vol 123 No 7 pages 1079-1082 July 1976.
- FIG. 6 One form of apparatus for performing the PAVD coating process is shown in Figure 6 to which reference is now made.
- a fibrous carbon permeable heating element 200 is supported horizontally by an alumina tube 201 inside the central region along the bore of a cylindrical silica tube 202 having enlarged ends 204, 205, the alumina tube 201 extending axially inside the silica tube 202 from an end cap 203 which closes the enlarged end 204.
- An outlet pipe 206 from the enlarged end 204 is connected through a vacuum-type valve 208 to a vacuum pump 209.
- the original fibrous carbon precursor 200 on which the coating has been deposited may either be retained, or removed by a heat treatment comprising oxidation in air at a temperature above 300°C so that a structure of tubular fibres of the deposited material remains.
- a suitable heat treatment may be used to adjust the electrical conductivity and temperature coefficient of resistance of the deposited material to desired values.
- this heat treatment must be carried out in an inert environment since it would normally take place above the carbon oxidation threshold temperature of about 300°C.
- this heat treatment may be effected before or after the carbon precursor is removed, or simultaneously with removal.
- the fibrous carbon precursor is placed in the tube 202 of Figure 6, and the tube 202 subsequently evacuated down to a vacuum pressure of about 10- 2 Torr.
- Argon is admitted through the gas supply line 220 to a vacuum pressure inside the tube 202 of about 1.0 Torr.
- the high frequency generator 238 is subsequently energised, and after about one hour, the silane/ethylene mixture to deposit the silicon and carbon is introduced into tube 202 through the gas supply line 222, and a mixture of phosphine/argon is introduced into the tube 202 through the gas supply line 224, the vacuum pressure inside the tube 202 being maintained at about 0.9 Torr.
- a suitable time interval e.g.
- An oxidation process to remove the fibrous carbon precursor may be carried out at any convenient temperature above about 300°C, but the time taken to oxidise the carbon can be reduced by increasing the oxidation temperature. Too high an oxidation temperature may however have an effect on the electrical properties of the coating which is not desired, and this possibility arises as a result of the nature of the material deposited during the PAVD coating process.
- TCR temperature coefficient of electrical resistance
- Example I Element carbonised at 650°C Density 150 kg/m 3
- the permeable electric heating elements may be of alternative shapes or sizes to those aforedescribed, and it will be understood that the heat transfer system in the aforedescribed aspects may be used in alternative applications, for example where the heat transfer fluid comprises a gas. Furthermore, the aforedescribed permeable electric heating elements may be used in alternative applications to heat a fluid.
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Resistance Heating (AREA)
- Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
Abstract
Description
- This invention relates to a fluid permeable, fibrous electric heating element for example for a heat transfer system and to said system, and to a process for manufacturing the heating element.
- The invention in a first aspect provides a process for manufacturing a fluid permeable, fibrous electric heating element, the process comprising forming a permeable fibrous precursor, coating fibres of the precursor with a material so as to form tubular fibres comprising the material, and heating the coated precursor so as to modify the structure of the material to provide a desired electrical resistivity of the tubular fibres.
- The precursor may be removed after coating thereof. Alternatively, the precursor might be retained within the tubular fibres, and might have an electrical resistivity either greater than or not exceeding that of the tubular fibres.
- In a second aspect, the invention includes a fluid permeable fibrous electric heating element made by the process of the first aspect of the invention, and might comprise tubular fibres comprising a silicon containing material for example, silicon, silicon carbide, or silicon nitride, or silicon and carbon together with silicon carbide, or silicon together with silicon carbide, or silicon together with silicon nitride.
- Desirably, the coating is produced by thadecomposition of a coating gas, and the coating gas might include a dopant for modifying the electrical resistivity of the coating.
- The heating element of the second aspect of the invention may be used for example in a heat transfer system comprising a circuit. adapted to contain a fluid, a heating element of the invention extending in a part of the circuit, and a heat transfer surface portion of the circuit for transferring heat from the fluid through the surface portion. The heat transfer surface portion may comprise a portion of a device for heating a material such for example as, a plastics material, a metal, paper, a textile, or a chemical substance.
- Examples of porous electric heating elements are described in British Patent Specification Nos 1466240 (United States Patent No 3943330), 1503644, and 1600253 (United States Patent No 4257157), these Specifications and Patents being incorporated by reference herein.
- It is frequently necessary to heat a fluid, either a gas or a liquid, electrically and to utilise a closed loop fluid circulating system to transfer this heat to other fluids or plant in a heat exchange system. A particular example is the use of a heated liquid (e.g. oil or water) for the purpose of controlling the temperature of moulds, dies, extruders and calenders used in the plastics industry. In existing designs of such temperature control units immersion electric elements of the metal sheathed type have been used, the heat generated in these elements being transferred by conduction through the metal sheath wall to the surrounding liquid which flows past the element. There is a limit to the heat transfer coefficient which can be used with this type of element if oil breakdown or element burnout is to be avoided, e.g. 1-20 watts cm2 of the element surface area. This factor exerts a consequent effect on the metal sheath size, and the size and weight of the heating system especially at tigh power ratings.
- Furthermore, the response of such units to a requirement for a change in the rate of heat transfer to the fluid is comparatively slow due to the appreciable heat capacity of the heating element itself, to the need to limit the element centre temperature to avoid melting the electrical conductor, and to the need to avoid high surface temperatures of the element sheath. This slow response can have a controlling influence on production cycle times when such temperature control units are used to heat moulds and dies in a production run of identical components.
- The invention largely overcomes these limitations by removing the sheathed metal element and replacing it with a fluid permeable fibrous electric heating element, and circulating the fluid through the body of the permeable heating element instead of over the external surface only. Power densitities exceeding 1 kW/cm3 of heating element material can then be attained, and this leads not only to a reduction in size and weight of a heating unit for a given duty but also a decrease in the response time such that the system can react virtually instantaneously to a demand for a large step increase in the heat generated and transferred to the circulating fluid.
- A suitable permeable heating element might comprise silicon, silicon carbide, or a mixture of silicon and silicon carbide, or silicon, carbon and silicon carbide, of a voidage of 50-98% and a bulk density of 50-750 kg/m3. The individual heating elements might consist of a matrix of fine or tubular fibres of a diameter.in the range 5-300 microns and wall thicknesses in the range 1-30 microns, a preferred range being 4-20 microns, and the space between the fibres providing the voidage. A thermal barrier/dispenser may be used in conjunction with the heating element to produce a uniform fluid flow (See U.K.
Patent No 1 466 240), especially where there is a hydrostatic pressure head variation over the heating element entry surface. - It may be desirable to maintain a heat generation rate and a fluid flow rate through the voidage in the heating element which restricts the fluid temperature rise across the heating element to not more than about 50°C, but this is not essential and temperature rises of 2-300°C or more are possible with a heating element wall thickness of 2-15 mm for an annular heating element. The heating element may have a predetermined electrical resistivity at a particular temperature, and a particular temperature coefficient of resistance, and may be suitable for mains voltage operation without the need for a transformer.
- The system components include a circulating pump, a heating element assembly, valves and pipework with the oil passing in series through the element and the mould, die, extruder, or calender to be heated together with a control system. 'Such units have been devised and operated at heating element power ratings in the range 1 - 30 kW for the aforementioned heating element geometry and with a response time of a few seconds. Very compact units can be designed and for the high power units, the small size which is attainable by the use of a high heating element power density rating reduces the cost of construction considerably compared with conventional heat transfer systems.
- The invention will now be further described by way of example only with reference to the accompanying drawings in which:-
- Figure 1 shows a schematic representation of a heat transfer system for heating a mould;
- Figure 2 shows to an enlarged scale a perspective representation of the mould usec4. in the system of Figure 1;
- Figure 3 shows in medial section and to an enlarged scale, a side view of an electric heating unit for use in the system of the invention;
- Figure 4 shows in medial section and to an enlarged scale, a side view of an alternative electric heating unit;
- Figure 4a shows a fragmentary sectional view on the line IVa-IVa of Figure 4;
- Figure 5 shows graphical representations of temperature against time for the unit of Figure 4; and
- Figure 6 shows a diagrammatic representation of a plasma activated vapour deposition apparatus.
- Referring now to Figure 1, the heat transfer system essentially comprises a mould 10 (e.g. an injection mould) connected by
piping 11 to acooling unit 13 and to a permeable elementelectric heating unit 14. A heat transfer oil in thepiping 11, such as British Petroleum (BP) Transcal N,is arranged to be circulated around the system by apump 15. Aninlet thermocouple 20 and an outlet thermocouple 21 are located about themould 10 to sense the temperature of the oil in thepiping 11, and amould temperature controller 23 senses the temperature of themould 10 and controls the operation of thecooling unit 13 and theheating unit 14 to 'maintain themould 10 at a desired temperature. A by-pass limb 25 having arelief valve 26 is connected to thepiping 11 in parallel with themould 10. - The
mould 10 as shown in greater detail in Figure 2 to which reference is made, is in two half-portions 10a and 10b respectively and hasoil ducts 18 in series with thepiping 11 for the circulation of the oil through themould 10, and a connecting pipe lla which may be flexible to facilitate separation and closure of the two half-portions 10a, lOb, for connecting theoil ducts 18 between the half-portions 10a, lOb, - Referring now to Figure 3, the permeable element
electric heating unit 14 is generally of circular form in transverse section, and comprises a fluid permeablefibrous heating element 30 of hollow cylindrical form, for example 120 mm long, and having gold platedcopper electrodes heating element 30 respectively. Thelower electrode 32 is joined to abrass end cap 34 that is joined to asteel tube 33 brazed to acopper rod 35 which is connected by a clamp-type terminal 36 to an electric supply (not shown). Twometal cooling discs 38 are disposed about therod 35 and are held by a "Starlock" retaining washer 40 located above theuppermost cooling disc 38, threeSchnorr washers 41 between thecooling discs 38 maintaining a compressive force on apad 42 which is arranged to bear on ashouldered collar 43 of an electrical insulating material. Ashouldered insert 45 of an electrical insulating material such as polyamide Tufnol locates in arecess 46 in ahousing 37 and supports an 'O'ring seal 48 disposed around therod 35, a flat annularupper spacer 49 of the same material as that of theshouldered insert 45 being urged against the 'O'ring seal 48 by theshouldered collar 43. - The
housing 37 which is joined to theupper electrode 31 has aninner chamber 52 connected to thepiping 11 and inlet ports 53 (only two are shown) connecting theinner chamber 52 to aspace 54 between the inside surface of theheating element 30 and the outside surface of thetube 33, thetube 33 having an upper-port 55 and alower port 56 connecting the bore of thetube 33 with thespace 54 and acts as a thermal dispenser. - The
housing 37 has atube portion 58 with anexternal flange 59 which is clamped to anexternal flange 62 of a tubularinner casing 63 in which theheating element 30 is disposed, an 'O'ring seal 65 being provided in anannular recess 66 and an earth terminal 60 attached to theflange 62. - A thermal insulant such as Kaowool is arranged as a lagging 70 between the
inner casing 63 and anouter casing 71, thepiping 11 extending through the lower portion of theouter casing 71 and the lagging 70 to the lower end of theinner casing 63, and an airbleed pipe 73 extending through the upper portion of theouter casing 71 and the lagging 70 to theinner casing 63. - In use of the
mould 10 for the forming of plastics articles (not shown), themould 10 is held at a desired operating temperature by the oil circulated through themould 10 by thepump 15. Thetemperature controller 23 senses the temperature of themould 10 and adjusts as appropriate either the rate of flow of a coolant (e.g. water) through thecooling unit 13 or the flow of the current to the porouselectric heating unit 14 so as to control the temperature of the oil and thus maintain themould 10 at the required operating temperature. Theoil temperature thermocouples 20, 21 provide an additional monitoring capacity and can actuate theheating unit 14 at some predetermined oil temperature or temperature difference of the oil across themould 10. - In an alternative arrangement, the oil may flow through the
heating unit 14 in the reverse direction to that shown. - A
shorter heating element 30 may be used in theheating unit 14, to overcome the problem of non-uniform flow which arises withlong heating elements 30 as a result of hydrostatic pressure differences along theheating element 30, and to increase the fluid velocity through theheating element 30 so that a high power generation density may be employed. An example of such a compact heating element is shown in Figure 4 in which anelectric heating unit 14a incorporates a fluid permeable fibrous heating element 80 of hollow cylindrical form and typically about 45 mm outside diameter, 35 mm inside diameter, and 10 mm long. Gold platedannular copper electrodes 81 and 82 are disposed at respective ends of the heating element 80, and eachelectrode 81, 82 is supported on aboss 83, 84 from a respective stainless steelannular backing disc backing disc 85 is supported on a .boss 87 from an annularelectrical insulator 88 of polyamide TUFNOL, and thebacking disc 86 is similarly supported on aboss 89 from anannular insulator 90 of polyamide TUFNOL. Thin gaskets (not shown) of a deformable material such as graphite, copper or aluminium may be provided between the ends of the element 80 and theelectrodes 81 and 82. - A stainless
steel dispenser rod 96 extends through and supports theinsulators insulator 90 is held against one side of the flange 97 by the action of acompression spring 98 which at one end thereof fits over aboss 110 from acap 99. Theboss 110 locates around one end of thedispenser rod 96, and thecap 99 is secured to thedispenser rod 96 by a screw 111. The other end of thespring 98 butts against theinsulator 88 to press theinsulators electrodes 81, 82, and theinsulator 90 tightly together. Anaxial hole 112 extends in thedispenser rod 96 from two axially spaced sets of four (only three are shown) equi-spaced radially extendingoutlet holes axial hole 112 extending in a direction towards the other end of thedispenser rod 96. - The
dispenser rod 96 at the other side of the flange 97 is screw threaded at 115, and locates inside a correspondingly threaded hole 116 in a hollowcylindrical bush 117 of polyamide TUFNOL to butt against ashoulder 119, and is held firmly in the threaded hole 116 by a stainlesssteel lock nut 121. Thebush 117 is threaded on its outside surface to locate inside a correspondingly threadedhole 123 extending from one side of a stainless steel mounting member 125 and butts against a shoulder 126, thebush 117 being firmly held thereto by a stainlesssteel lock nut 128. A relatively small diametercylindrical hole 130 at the axial centre of theshoulder 119 and the mounting member 125 leads to a threaded hole 132 at the other side of the mounting member 125 in which a compression-type pipe coupling 134 locates to connect thepiping 11 to the mounting member 125. The mounting member 125 is integral with acircular flange 137 which is held by several bolts 138 (only two are shown) to anannular flange 140 of a hollowcylindrical casing 142, an annularsoft copper gasket 144 providing a seal between theflanges electrode assemblies respective holes flange 137, and are welded to theflange 137 to provide a pressure tight joint. Eachelectrode assembly electric supply cables electrical connections copper terminal member 155, 156 secured as shown in Figure 4a to ashoulder 157 of therespective electrode 81 or 82. Suitablesuch electrode assemblies - An
end plate 160 closes thecasing 142, and has a threadedhole 162 for athermocouple connection 164, an axially located threadedhole 166 for another compressiontype pipe coupling 134 to connect the interior of thecasing 142 with the piping 11, a threadedhole 168 for ahydraulic pressure valve 169, and a narrow threaded hole 171 for an automaticair relief valve 172. A thermal insulant 174 (e.g. Kaowool) surround theheating unit 14a but is shown only partially distributed thereabout for clarity. - In operation, with the
heating unit 14a in place of theheating unit 14 in the heat transfer system of Figure 1, oil flows through the piping 11 (typically at 1-10 litre/minute) and enters theaxial hole 112 in thedispenser rod 96 to emerge through the outlet holes 113, 114, inside the heating element 80. After flowing through the heating element 80, the oil issues into thecasing 142, and leaves through thepipe coupling 134 to re-enter thepiping 11 and circulate through themould 10. With thecables temperature controller 23 senses the temperature of themould 10 and switches the electric supply to the heating element 80 off and on as desired to control the temperature of the oil flowing through theheating unit 14a and thus to maintain themould 10 at the required operating temperature. Because of the rapid speed of response of the heating element 80 when the electric supply is switched on, close control of the temperature of themould 10 is obtained, and an example of this is shown graphically in Figure 5 which illustrates for a heating element 80 containing silicon carbide rated at 3.4 kW" at 231.5°C a plot of temperature v time for - (1) oil into the
mould 10 - (2) oil leaving the
mould 10 - (3) temperature of the
mould 10 - The magnitude of the
heating unit 14 power output depends inter alia on the electric supply voltage, the electrical resistance of the heating element 80 and the number of such elements 80, and is typically in the range 1-50 kW per element. - The succession of short vertical lines relating to the temperature of the oil entering the
mould 10 when a steady temperature condition is reached indicates the rapid response of the heating element 80 as the electric supply thereto is repetitively switched on and off to maintain themould 10 at the required operating temperature, which in the case illustrated in Figure 5 is 225°C. - If desired the oil may be arranged to flow through the
heating unit 14a in the reverse direction to that shown. - The porous electric heating element may be made from a precursor in the form of a permeable fibrous carbon electric heating element comprising carbon fibres, made for example as described in the aforementioned patent Specifications, and coated with material conveniently applied by a plasma assisted deposition process (hereinafter referred to as PAVD). The electrical properties of this deposited material, which may be modified after deposition by appropriate heat treatments may largely determine the electrical operating characteristics of the porous electric heating element. The permeable fibrous carbon precursor on which the material is deposited by the PAVD process may be retained, or may be removed from beneath the deposited material by means of an oxidation process.
- In the PAVD process a plasma is used as a medium for chemical reaction, and deposition of a coating on a substrate is achieved through the decomposition of a gas in an electrically-induced plasma. An example of the plasma assisted deposition process is described in British Patent Specification No 2056829A, and related techniques are disclosed in the paper "Codeposition of Glassy Silica and Germania inside a Tube by Plasma Activated CVD" by D. Kuppers et al, Journal of the
Electrochemical Society Vol 123No 7 pages 1079-1082 July 1976. - One form of apparatus for performing the PAVD coating process is shown in Figure 6 to which reference is now made. In Figure 6 a fibrous carbon
permeable heating element 200 is supported horizontally by analumina tube 201 inside the central region along the bore of acylindrical silica tube 202 having enlarged ends 204, 205, thealumina tube 201 extending axially inside thesilica tube 202 from anend cap 203 which closes theenlarged end 204. Anoutlet pipe 206 from theenlarged end 204 is connected through a vacuum-type valve 208 to avacuum pump 209. The otherenlarged end 205 is closed by aninlet end cap 210 which has a feed pipe 212 to amercury pressure gauge 214, and aninlet 216 connected to a manifold 218 fed bygas supply lines respective valve silica vessel 226 of annular form is movable along the outside of thetube 202 and is shown surrounding the central region of thetube 202. Thevessel 226 supports an electrically isolated susceptor 228 (e.g. graphite), and is evacuated down to about 1 to 10 Torr through avacuum valve 230 by avacuum pump 232. Thevessel 226 is itself surrounded by a helical water-cooledcopper coil 236 having eight turns and which is coupled to a highfrequency power supply 238 for working in the frequency range of 104-108 Hertz.Earth connections heating element 200, theend cap 203, and theenlarged end 204 respectively. Thehigh frequency generator 238 is similarly earthed by aconnection 246. It may in some instances be advantageous to bias theconnection 240 positively or negatively to earth and to connect theelement 200 to theconnection 240 by a metallic conductor strip (not shown). - In operation, the
tube 202 is evacuated down to about 1-10-2 Torr by thevacuum pump 209, and then filled with argon through thegas supply line 220 to a vacuum pressure inside thetube 202 of between IO-2-100 Torr. The highfrequency power supply 238 is energised typically at an anode voltage of 1-4 kV and 4 x 105 Hertz, and a plasma is created about thecarbon precursor 200 whilst thesusceptor 228 is heated by electrical induction and heats thecarbon precursor 200. After about 15 to 30 minutes when thecarbon precursor 200 has reached thermal equilibrium and its surfaces have been cleaned by ion bombardment from the ionised gaseous argon, the selected reactant gas or gases are introduced through the appropriate gas supply lines 222 and/or 224 into thetube 202, and the pressure inside thetube 202 maintained in the range 10-1 to 100 Torr by adjustment of theappropriate valve 223, 225 and use of thevacuum valve 208 and thevacuum pump 209. A coating of the selected material is now applied to the surfaces of the fibres of thecarbon precursor 200 by the reactant gases, and the thickness of the material deposited is proportional to time. For example a coating of 1 to 20 pm might be deposited in about 24 hours. Thevalves frequency power supply 238 switched off, whilst thetube 202 continues to be evacuated by thevacuum pump 209 to allow thecoated element 200 to cool under vacuum conditions (e.g. 10-2 Torr), after which thecoated precursor 200 is removed from thetube 202. - Subsequently the original
fibrous carbon precursor 200 on which the coating has been deposited may either be retained, or removed by a heat treatment comprising oxidation in air at a temperature above 300°C so that a structure of tubular fibres of the deposited material remains. A suitable heat treatment may be used to adjust the electrical conductivity and temperature coefficient of resistance of the deposited material to desired values. In cases where thefibrous carbon precursor 200 is retained, this heat treatment must be carried out in an inert environment since it would normally take place above the carbon oxidation threshold temperature of about 300°C. When the fibrous carbon precursor is removed by oxidation and the coating is subjected to a heat treatment to adjust its electrical characteristics, this heat treatment may be effected before or after the carbon precursor is removed, or simultaneously with removal. The coating of thefibrous carbon precursor 200 may be performed in the apparatus of Figure 6 using, for example gases containing silicon and carbon, e.g. a silane/ethylene mixture, as the reactant gases to deposit a coating containing silicon and carbon on thefibrous carbon element 200. Phosphine gas may be used as a dopant together with the silane/ethylene if desired to assist in modifying the coating's electrical conductivity by co-depositing phosphorous with silicon and carbon in the coating. Other suitable dopants may be aluminium, or boron, or arsenic, or nitrogen, or oxygen, the purpose of the dopant being to increase the electrical conductivity of the deposited material by providing an electron donor or acceptor material, so that the final desired electrical resistivity of the heating element can be obtained at lower heat treatment temperatures than would otherwise be required. The heat treatment of the coating to modify its electrical resistivity is normally carried out at 800°-1400°C to achieve a particular resistivity of the deposited coating at a selected temperature. In many instances the use of phosphine gas as a dopant allows the heat treatment temperature to achieve a particular coating resistivity to be reduced to about 600-l100°C. An Example of the production of such a heating element by the PAVD process is as follows:- - Typical fabrication procedure parameters used are given below:- Y,
-
-
-
-
-
- The fibrous carbon precursor is placed in the
tube 202 of Figure 6, and thetube 202 subsequently evacuated down to a vacuum pressure of about 10-2 Torr. Argon is admitted through thegas supply line 220 to a vacuum pressure inside thetube 202 of about 1.0 Torr. Thehigh frequency generator 238 is subsequently energised, and after about one hour, the silane/ethylene mixture to deposit the silicon and carbon is introduced intotube 202 through the gas supply line 222, and a mixture of phosphine/argon is introduced into thetube 202 through thegas supply line 224, the vacuum pressure inside thetube 202 being maintained at about 0.9 Torr. After a suitable time interval (e.g. 48 hours) depending on the thickness of coating required (typically 0.8 grammes/hour are deposited), thevalves tube 202 evacuated to about 10-2 Torr and thehigh frequency generator 238 switched off to allow the coated precursor to cool under vacuum conditions. The coated precursor is subsequently removed from thetube 202 and cut into appropriate lengths prior to oxidation to remove the fibrous carbon precursor and such further heat treatment as may be required to modify the electrical resistivity of the coating. - An oxidation process to remove the fibrous carbon precursor may be carried out at any convenient temperature above about 300°C, but the time taken to oxidise the carbon can be reduced by increasing the oxidation temperature. Too high an oxidation temperature may however have an effect on the electrical properties of the coating which is not desired, and this possibility arises as a result of the nature of the material deposited during the PAVD coating process.
- The as deposited material in Example I essentially consists of free carbon, free silicon, carbon combined chemically with silicon as silicon carbide, and a relatively small amount of phosphorous. Heat treatment of this material changes the electrical properties of the coating to a degree which is influenced by the heat treatment temperature and time. Thus it is possible to either heat treat in an inert atmosphere at a relatively high temperature to obtain a selected resistivity, and to follow this by oxidation at a lower temperature, or to oxidise at a relatively low temperature and to follow this process with one or more heat treatment stages in an inert or oxidising atmosphere to adjust the coating restivity to the desired value. In some cases depending on the PAVD coating process parameters employed it will be possible to carry out a one stage heat treatment process which both removes the fibrous carbon precursor by oxidation and adjusts the resistivity of the coating to a desired value. Oxidation removes not only the carbon precursor but also may remove some or all of the elemental carbon in the coating. Consequently the final coating resistivity depends not only on the temperature and time of the heat treatment but also on whether or not the oxidation stage is carried out first. Additionally some-of the free silicon may become oxidised if the oxidation temperature is very high.
- The heat treatment time and temperature to produce a required coating resitivity is not a unique process, and depends not only on the PAVD coating parameters, for example the gas composition and flow rates and RF conditions, but also on the electrical properties of the carbon precursor on which the coating is deposited. The electrical resistivity of the fibrous carbon precursor during the coating process is a function not only of the carbonisation temperature of the carbon precursor but also of the RF field conditions through its effect on the temperature of the carbon precursor during the coating process. It has been found that the composition of the material deposited during the coating process and its electrical properties is influenced by both the RF field voltage and the carbonisation temperature to which the carbon precursor was subjected, and that the heat treatment procedure required to obtain a particular electrical resistivity of the deposited material depends on its composition. Consequently some combinations of PAVD parameters and carbon precursor carbonisation temperatures can allow a given resistivity of the deposited material to be obtained together with a low temperature coefficient of resistance of the deposited material after heat treatment, whereas others may not. Furthermore the use of a dopant such as phosphorous in the PAVD coating process changes the relationship between resistivity, heat treatment conditions, and temperature coefficient of resistance.
- Removing the phosphorous from the coating gases and substituting arsenic or boron for phosphorous also changes the composition of the material deposited and affects the heat treatment process required to attain a particular resistivity. Properties of heating elements made in a way similar to that outlined in Example I but with or without a dopant respectively are described in the following Examples II and III.
- As in Example I: Elements carbonised at 725°C Density 103 kg/m3
-
-
-
- As in Example I: Element carbonised at 1000°C Density 106 kg/m3
-
-
-
-
- The method of Example I may also be used to produce a coating which contains silicon but not to a substantial extent, if at all, silicon carbide. This is achieved by substituting silane for the mixture of silane and ethylene in Example 1. Such coatings may also be doped, for example with phosphorous, arsenic, boron, nitrogen, or oxygen, or be undoped. Example IV illustrates such a silicon element doped with nitrogen.
-
-
-
-
-
- As a general rule increasing the time and the temperature of heat treatment of the coating up to a heat treatment temperature of about 1400°C, reduces the electrical resistivity of the coating provided material is not lost by evaporation.
- When the heating element is to be used over a relatively wide temperature range (e.g. 20°C to 200°C), the temperature coefficient of electrical resistance (TCR) of the heating element may become of importance. Examples V and VI illustrate the variation in TCR values arising from different precursor and process conditions.
- As in Example I: Element carbonised at 650°
C Density 150 kg/m3 -
-
-
-
- As in Example I: Element carbonised at 725°
C Density 130 kg/m3 -
-
-
- Subsequent heat treatment
-
-
- Comparison of Examples V and VI gives the following:-
-
- In Example V the resistance ratio is lower than in
- Example VI in spite of the fact that the heat treatment was carried out at a lower temperature than was used for Example VI. This illustrates the significant effect of substrate carbonisation temperature and kv since it has also been found that the resistance ratio normally falls as the heat treatment temperature is increased and on this basis alone the resistance ratio of Example VI would be expected to be lower than the value established by Example V. Selection of substrate carbonisation temperature and kV is therefore one way of obtaining a desired value of the resistance ratio R20/R200.
- By way of comparison, a silicon carbide heating element made by carbonisation at 1700°C of a fibrous carbon precursor, coating of the precursor, and subsequent heat treatment of the coated precursor at 1385°C, was found to have a resistance ratio (R20/R200) of 8.49, whereas a precursor carbonised at 650°C and the coated precursor heat treated at 1185°C was found to have a resistance ratio (R20/R200) of 1.48. Thus by appropriate selection of the carbonisation temperature, the coating conditions and the heat treatment temperature, heating elements having a required electrical resistivity and TCR may be made.
- Although the coating of the fibrous carbon has been described in relation to PAVD, it will be understood that appropriate alternative coating processes may be used.
- The permeable electric heating elements may be of alternative shapes or sizes to those aforedescribed, and it will be understood that the heat transfer system in the aforedescribed aspects may be used in alternative applications, for example where the heat transfer fluid comprises a gas. Furthermore, the aforedescribed permeable electric heating elements may be used in alternative applications to heat a fluid.
- It will be understood that where the carbon fibres in the fibrous carbon precursor are contiguous, the coatings about the fibres may merge together at these positions of contiguity. Hence when the coated precursor is oxidised, the tubular fibres that remain may be integral with closely adjacent tubular fibres at the positions of contiguity. Otherwise the coating material deposited substantially replicates the geometry and fibre distribution pattern of the original fibrous carbon precursor.
- For some applications the fibrous carbon precursor need not be removed, but may be allowed to remain in situ during any heat treatment of the coating which should then be carried out in an inert atmosphere. The electrical resistivity of the heating element would then be a combination of the resistivity of the fibrous carbon precursor and the selected resistivity of the coating. The electrical resistivity of the coating may be the same or greater than that of the carbon precursor, but in some cases it may be desirable that the electrical resistivity of the heating element is determined mainly by the coating, so that under operating conditions the coating carries the majority of the electric current. The electrical resistivity of the fibrous carbon precursor should, therefore, be substantially greater than the electrical resistivity of the coating after the final heat treatment to adjust the electrical resistivity of the coating has been completed.
- A relatively high electrical resistivity of the fibrous carbon precursor may be achieved by selecting a relatively low carbonisation temperature, e.g. below about 800°C, and this implies that the PAVD coating parameters must be selected so as to ensure that the heat treatment required to achieve a desired coating resistivity may be carried out at a temperature which is preferably below the carbonisation temperature of the fibrous carbon precursor. It will be appreciated that for some applications a precursor of an insulating material may be used for the precursor for coating in the PAVD apparatus of Figure 6, and retention during subsequent heat treatment stages.
- If desired, coatings of alternative materials to those aforedescribed may be deposited in the PAVD apparatus of Figure 6, not necessarily silicon-containing coatings, depending on the application to which the heating elements are to be put. Coatings may also be applied in the PAVD apparatus of Figure 6 on precursors for alternative applications, which precursors might be retained as aforementioned, the coating being subjected to subsequent heat treatment to provide a desired electrical resistivity of the coating.
Claims (23)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8137673 | 1981-12-14 | ||
GB8137673 | 1981-12-14 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0082627A1 true EP0082627A1 (en) | 1983-06-29 |
EP0082627B1 EP0082627B1 (en) | 1988-01-27 |
Family
ID=10526598
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP82306494A Expired EP0082627B1 (en) | 1981-12-14 | 1982-12-06 | An improved fluid permeable porous electric heating element |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0082627B1 (en) |
JP (1) | JPS58112296A (en) |
DE (2) | DE82627T1 (en) |
GB (1) | GB2111809B (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2911720A4 (en) * | 2012-10-29 | 2015-09-02 | Forever Young Int Inc | Temperature changing intracorporeal fluid delivery devices |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2264617A (en) * | 1991-10-08 | 1993-09-01 | Atomic Energy Authority Uk | Porous heating element |
DE102019203227A1 (en) * | 2019-03-11 | 2020-09-17 | Audi Ag | Forming tool for primary forming or reshaping of a workpiece with a temperature control device |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2408802A1 (en) * | 1973-02-26 | 1974-08-29 | Atomic Energy Authority Uk | HEATING DEVICE FOR HEATING FLUIDS |
GB1503644A (en) * | 1975-04-21 | 1978-03-15 | Fogarty & Co Ltd E | Method and apparatus for forming fibrous cylindrical element |
DE2822536A1 (en) * | 1977-05-23 | 1979-01-25 | Atomic Energy Authority Uk | METHOD OF MAKING A FLUID-PERMEABLE ELECTRIC RESISTANCE HEATING ELEMENT |
DE3022259A1 (en) * | 1979-06-14 | 1980-12-18 | Atomic Energy Authority Uk | HEAT TRANSFER AND HEATING DEVICE |
DE3040693A1 (en) * | 1979-11-08 | 1981-05-27 | Deutsche Itt Industries Gmbh, 7800 Freiburg | METHOD FOR METALIZING SEMICONDUCTOR COMPONENTS |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3742192A (en) * | 1972-02-02 | 1973-06-26 | J Brzuszek | Electrical heating device and method |
JPS5117040A (en) * | 1974-08-02 | 1976-02-10 | Tokyo Shibaura Electric Co | KAABON HATSUNET SUTAI |
-
1982
- 1982-12-06 GB GB08234714A patent/GB2111809B/en not_active Expired
- 1982-12-06 DE DE1982306494 patent/DE82627T1/en active Pending
- 1982-12-06 EP EP82306494A patent/EP0082627B1/en not_active Expired
- 1982-12-06 DE DE8282306494T patent/DE3278066D1/en not_active Expired
- 1982-12-14 JP JP21912382A patent/JPS58112296A/en active Granted
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2408802A1 (en) * | 1973-02-26 | 1974-08-29 | Atomic Energy Authority Uk | HEATING DEVICE FOR HEATING FLUIDS |
GB1503644A (en) * | 1975-04-21 | 1978-03-15 | Fogarty & Co Ltd E | Method and apparatus for forming fibrous cylindrical element |
DE2822536A1 (en) * | 1977-05-23 | 1979-01-25 | Atomic Energy Authority Uk | METHOD OF MAKING A FLUID-PERMEABLE ELECTRIC RESISTANCE HEATING ELEMENT |
DE3022259A1 (en) * | 1979-06-14 | 1980-12-18 | Atomic Energy Authority Uk | HEAT TRANSFER AND HEATING DEVICE |
DE3040693A1 (en) * | 1979-11-08 | 1981-05-27 | Deutsche Itt Industries Gmbh, 7800 Freiburg | METHOD FOR METALIZING SEMICONDUCTOR COMPONENTS |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2911720A4 (en) * | 2012-10-29 | 2015-09-02 | Forever Young Int Inc | Temperature changing intracorporeal fluid delivery devices |
Also Published As
Publication number | Publication date |
---|---|
JPS58112296A (en) | 1983-07-04 |
GB2111809A (en) | 1983-07-06 |
JPH0416914B2 (en) | 1992-03-25 |
EP0082627B1 (en) | 1988-01-27 |
DE3278066D1 (en) | 1988-03-03 |
GB2111809B (en) | 1985-08-21 |
DE82627T1 (en) | 1984-02-16 |
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