Spot heater

Patent metadata

Field	Value
Publication number	US-11937342-B2
Application number	US-202017030329-A
Country	US
Kind code	B2
Filing date	Sep 23, 2020
Priority date	Sep 23, 2019
Publication date	Mar 19, 2024
Grant date	Mar 19, 2024

Abstract

A device is described in which the shape of a resistive heater material is configured to provide rapid and strong heating of a small area. The resistive heating material is heated unevenly while efficiently using power.

First claim

What is claimed:

1. A spot heater, comprising:
a sheet of resistive heating material that comprises an area or areas of reduced cross-sectional area which are adapted to constrict current flow through the sheet of resistive heating material;
and an actuator for providing electrical current through the sheet; and
wherein the area or areas of reduced cross-sectional areas are formed by opposing notches in the resistive heating material wherein each of the opposing notches has a feature angle of between 5 and 60 degrees.

2. The spot heater of claim 1 comprising at least one electrical connection of the sheet to an anode and at least one electrical connection of the sheet to a cathode.

3. The spot heater of claim 1 wherein each of the opposing notches has a feature angle of between 5 and 40 degrees.

4. The spot heater of claim 1 wherein the opposing notches notch creates a gap having a gap height and wherein each notch has incoming and outgoing constriction angles of at least 70 degrees on both sides of the gap.

5. The spot heater of claim 1 wherein the sheet of resistive heating material comprises outer edges that contact busbars and wherein the area or areas of reduced cross sections have cross sectional areas that are at least 50% smaller than areas toward the outer edges.

6. The spot heater of claim 5 wherein temperature in a hot spot during operation is at least 100 K hotter than other areas of the sheet of heating material.

7. The spot heater of claim 1 wherein the sheet of resistive heating material has a plurality of cut-outs or openings and wherein, during operation, hot spots occur at constrictions between the cut-outs or openings in material.

8. The spot heater of claim 7 wherein the cut-outs or openings are voids.

9. The spot heater of claim 7 wherein the cut-outs or openings are filled with an insulating material.

10. The spot heater of claim 1 wherein the sheet material comprises at least 5 hot spots created by areas of constrained current flow during operation.

11. The spot heater of claim 1 wherein the sheet has a surface area of at least 10-cm 2 and where each hot spot has an area of between 0.1 to 2 cm 2 ; wherein a single sheet of the resistive heating material comprises at least 10 cut-outs or openings and 10 hot spots.

12. A spot heater, comprising:
a sheet of resistive heating material that comprises an area or areas of reduced cross-sectional area which are adapted to constrict current flow through the sheet of resistive heating material;
and an actuator for providing electrical current through the sheet;
wherein the resistive sheet is a triangle with an anode connected at one edge of the triangle through a busbar and a cathode connected to an opposite point of the triangle.

13. A method of resistive heating, comprising:
providing a sheet of a resistive heating material that comprises an area or areas of reduced cross-sectional area which are adapted to constrict current flow through the sheet of heating material;
passing an electric current through the sheet such that the area or areas adapted to constrict current flow become a hot spot or hot spots that increase in temperature to a temperature that is at least 5 K greater than the average temperature of the sheet; and
wherein the area or areas of reduced cross-sectional areas are formed by opposing notches in the resistive heating material wherein each of the opposing notches has a feature angle of between 5 and 60 degrees.

14. The method of claim 13 wherein the opposing notches in the resistive heating material creates the hot spot; wherein the opposing notches create a gap having a gap height and wherein each notch has incoming and outgoing constriction angles of at least 70 degrees on both sides of the gap.

15. The method of claim 13 wherein the temperature in a hot spot is at least 100 K hotter than other areas of the sheet of heating material.

16. The method of claim 13 wherein the hottest contiguous 10% of the sheet is at least 50 K hotter than the 50% of the sheet where the resistive sheet is coldest as measured at the sheet surface.

17. The spot heater of claim 1 wherein the sheet of resistive heating material comprises conductive fibers.

18. The spot heater of claim 17 wherein the fibers are non-aligned.

19. The spot heater of claim 17 wherein the fibers comprise carbon nanotubes.

20. The method of claim 13 wherein the sheet of resistive heating material comprises outer edges that contact busbars and wherein the area or areas of reduced cross sections have cross sectional areas that are at least 40% smaller than areas toward the outer edges.

Assignees

• Battelle Memorial Institute

Inventors

• Palmer Katherine M
• Bosworth Kurt
• Yugulis Kevin
• Heintz Amy M
• Ellis Jeffrey L

Classifications

• H05B3/0004 Primary

  Devices wherein the heating current flows through the material to be heated (Circuit arrangements for heating by passing the current directly across the material to be heated H05B3/0023; granular, powdered or fluid material H05B3/60) · CPC title

• H05B3/03

  Electrodes · CPC title

• H05B3/10

  Heating elements characterised by the composition or nature of the materials or by the arrangement of the conductor · CPC title

• H05B3/34 Primary

  flexible, e.g. heating nets or webs · CPC title

• H05B2203/007

  using multiple electrically connected resistive elements or resistive zones · CPC title