Method and apparatus utilizing a porous vitreous carbon body particularly for fluid heating

• US 4,310,747 A
• Filed: 03/07/1980
• Issued: 01/12/1982
• Est. Priority Date: 07/26/1978
• Status: Expired due to Term

• Current Assignee: Furon Company (Compagnie De Saint-Gobain S.A.)
• Original Assignee: The Fluorocarbon Company (Compagnie De Saint-Gobain S.A.)
• Inventors: Rice, Warren A., Franklin, Charles H., Vinton, Clarence S., Torbett, Christopher J.
• Primary Examiner(s): Grimley, Arthur T.
• Assistant Examiner(s): Roskoski, Bernard
• Application Number:
  US06/128,193
• Time in Patent Office: 676 Days
• Field of Search: 219/368-382, 219/553, 219/10.55 F, 219/10.55 M, 219/10.53, 219/10.57, 219/10.49, 264/29, 423/444, 423/449, 423/445, 423/447.7, 423/447.9, 423/447.8, 29/610, 29/611, 252/500, 252/502, 252/504, 252/510, 252/511, 252/517, 338/224, 338/225, 126/415, 126/449, 165/485
• US Class Current: 392/466
• CPC Class Codes: F24H 3/0405 using electric energy supply, e.g. the heating medium being a resistive element; Heating by direct contact, i.e. with resistive elements, electrodes and fins being bonded together without additional element in-between F24H3/06, F24H3/08, F24H3/10 take precedence
• CPC Class Codes: F24H 9/1863 Arrangement or mounting of electric heating means
• CPC Class Codes: H01C 7/00 Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material consisting of loose powdered or granular material H01C8/00; resistors having potential barriers, e.g. field-effect resistors, H01L29/00; semiconductor devices sensitive to electromagnetic or corpuscular radiation, e.g. photoresistors, H01L31/00; magnetic field controlled resistors H10N50/10; bulk negative resistance effect devices H10N80/00
• CPC Class Codes: H05B 3/145 Carbon only, e.g. carbon black, graphite

Abstract

A body of a specially prepared, porous vitreous carbon which does not crack or substantially change in electrical resistance with time when heated to elevated temperatures in air and which is used in a method or apparatus to heat a fluid stream flowing in the pores of the body as a result of natural convection or pumping of the fluid is described. The body is composed of electrically conductive rigid, interconnected and multidirectional continuous strands of vitreous carbon forming a rigid porous, three dimensional skeletal structure. The body as an electrical resistance element has current conductive paths between at least two regions; is shaped to provide particular cross-sections along the conductive paths; and has electrical connector means attached at the regions of the body so that current can be distributed through the body. The electrical resistance element is particularly useful as a heating element for air flowing through the pores in electrically powered room space heaters, hair dryers, hand dryers and the like and can also function as a self-cooling resistor. In a like manner, electromagnetic energy is used to heat a body of the porous vitreous carbon so as to heat a fluid stream flowing through the pores.

Claims

1. A method for supplying heat to a fluid which comprises:

(a) providing a body of rigid, interconnected, multidirectional and continuous strands of vitreous carbon forming a rigid, porous, three dimensional skeletal structure, said body being so structured that it can withstand sustained heating in air to about nominally 350°

C. without cracking or significant electrical resistance change measured at room temperature; and

(b) supplying electrical or electromagnetic energy to the body such that a fluid flowing in the body is heated by heat transfer.

2. The method of claim 1 wherein the fluid is air and the body is heated to about 125°

C. or less in the presence of air which is forced through the body.

3. The method of claim 1 wherein the electromagnetic energy is solar or radiofrequency.

4. A method for supplying heat to a fluid which comprises:

(a) providing a body of rigid, interconnected, multidirectional and continuous strands of vitreous carbon forming a rigid, porous, three dimensional skeletal structure, said body having been heat treated to at least about 1800°

C. in a non-reactive atmosphere; and

(b) supplying electrical or electromagnetic energy to the body such that a fluid flowing in the body is heated by heat transfer, wherein the body is at a temperature such that the body has an electrical resistance measured at room temperatures which remains substantially constant with time in the presence of the heated fluid.

5. An apparatus for supplying heat to a fluid stream which comprises:

(a) a body of rigid, interconnected, multidirectional and continuous strands of vitreous carbon forming a rigid, porous, three dimensional skeletal structure, said body being so structured that it can withstand sustained heating in air to nominally about 350°

C. without cracking or significant electrical resistance change measured at room temperature;

(b) means for supplying electrical or electromagnetic energy to the body, such that the body is heated by the energy; and

(c) means for supplying a fluid stream through the body such that the fluid stream is heated by heat transfer with the heated body.

7. The apparatus of claims 5 or 6 wherein the electromagnetic energy is solar or radiofrequency.

6. An apparatus for supplying heat to a fluid stream which comprises:

(a) a body of rigid, interconnected, multidirectional and continuous strands of vitreous carbon forming a rigid, porous, three dimensional skeletal structure, said body having been heat treated to at least about 1800°

C. in a non-reactive atmosphere;

(b) means for supplying electrical or electromagnetic energy to the body, such that the body is heated by the energy; and

(c) means for supplying a fluid stream through the body such that the fluid stream is heated by heat transfer with the heated body and such that the body has an electrical resistance measured at room temperature which remains substantially constant with time in the presence of the heated fluid stream.