# US 4,395,620 A · Electric storage heating apparatus

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- Number: US 4,395,620 A
- Document ID: US4395620A
- Status: Granted
- Kind: A
- Application number: 06/237,573
- Filed: 1981-02-23
- Granted: 1983-07-26
- Earliest claimed: 1981-02-23
- Inventors: Robert A. Clyde; William B. Crandall
- Web page: https://patentgrep.com/patent/US4395620A

## CPC

- F24H 7/0416: {the transfer fluid being air}
- F24H: FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL (steam generation F22)

## Abstract

An electric heat storage apparatus comprises an electric heating element, a ceramic heat storage pipe, an air passageway in communication with the pipe, and a thermostatically controlled air circulation means. The ceramic pipe has a scalloped-shaped outer surface providing a plurality of crests and troughs and a series of parallel grooves cut in at least some of the crests. The heating element is located in the grooves in contact with the pipe. In a preferred embodiment, the pipe is provided with a plurality of internal ribs of at least two different lengths. The pipe is supported on a ceramic cradle and a ceramic sponge or metal turnings are inserted into the pipe between the ribs to increase the heat transfer area.

## Claims

### Claim 1

In an electric heat storage apparatus having (1) an electric heating element, (2) a heat storage core, (3) an air passageway in communication with the core, and (4) thermostatically controlled air circulation means, the improvement wherein said heat storage core comprises a ceramic pipe having a scallop-shaped outer surface providing a plurality of crests and troughs and a series of parallel grooves cut in at least some of the crests, and said heating element is located in said grooves in contact with said pipe.

### Claim 2 (depends on 1)

The improvement according to claim 1 wherein said heating element comprises a continuous length of resistance wire wound in said grooves with said troughs providing cross-over connections from one groove to an adjacent groove.

### Claim 3 (depends on 1)

The improvement according to claim 1 wherein parallel grooves are cut in all of said crests except one and slanting grooves are cut in the remaining crest that connect adjacent parallel grooves.

### Claim 4 (depends on 1)

The improvement according to claim 1 wherein said pipe is a material selected from the group consisting of petalite, spodumene, or cordierite.

### Claim 5 (depends on 1)

The improvement according to claim 1 wherein a ceramic sponge is located in the core of said pipe, said sponge comprising a network of randomly located, closely adjacent ceramic filaments defining a plurality of interconnected cavities.

### Claim 6 (depends on 5)

The improvement according to claim 5 wherein said ceramic sponge has a plurality of internal voids.

### Claim 7 (depends on 5)

The improvement according to claim 5 wherein said ceramic sponge is coated with a metal.

### Claim 8 (depends on 5)

The improvement according to claim 5 wherein said ceramic sponge is coated with alumina.

### Claim 9 (depends on 1)

The improvement according to claim 1 wherein metal shavings are located in the core of the pipe.

### Claim 10

An electric heat storage apparatus comprising:
(a) a housing having an air passageway;
(b) a ceramic pipe located in said housing in communication with said passageway, said pipe having a scallop-shaped outer surface providing a plurality of crests and troughs, (2) a plurality of internal ribs on it interior surface, and (3) a series of parallel grooves cut in at least some of said crests; and
(c) a resistance wire located in said grooves in contact with said pipe.

### Claim 11 (depends on 10)

The apparatus according to claim 10 wherein said internal ribs are of at least two different lengths.

### Claim 12 (depends on 10)

The apparatus according to claim 10 wherein said pipe is a material selected from the group consisting of petalite, spodumene, or cordierite.

### Claim 13 (depends on 10)

The apparatus according to claim 10 further comprising a ceramic sponge located in the core of said pipe, said sponge comprising a network of randomly located, closely adjacent ceramic filaments defining a plurality of interconnected cavities.

### Claim 14 (depends on 13)

The apparatus according to claim 13 wherein said sponge has a plurality of spiral voids.

### Claim 15 (depends on 13)

The apparatus according to claim 13 wherein said sponge is coated with a metal.

### Claim 16 (depends on 13)

The apparatus according to claim 13 wherein said sponge is coated with alumina.

### Claim 17 (depends on 10)

The apparatus according to claim 10 further comprising metal shavings located in the core of said pipe.

### Claim 18 (depends on 10)

The apparatus according to claim 10 further comprising a ceramic cradle supporting said pipe in said air passageway.