US1446317A

US1446317A - Electrical liquid heater

Info

Publication number: US1446317A
Application number: US562731A
Authority: US
Inventors: Penzold Wilhelm
Original assignee: WIDERSTAND AG fur ELEKTRO WARM
Current assignee: WIDERSTAND AG fur ELEKTRO WARM; WIDERSTAND AG fur ELEKTRO-WARME-TECHNIK
Priority date: 1922-05-22
Filing date: 1922-05-22
Publication date: 1923-02-20
Anticipated expiration: 1940-02-20

Description

Feb. 20, 19.23. 1,446,317 w. PENzoLD vELECTRICAL LIQUID HEATER Filed May Z, 1922 2 sheets-sheet l Feb. zo, 1923. 1,446,317 W. PEvNZOLD 2 ELECTRI CAL LIQUID HEATER Filed May 22, 1922 2 Sheets-sheen 2 Maf/erg Patented Feb. 20, 1923.

UNITED STATESv 1,446,317 PATENT OFI-leef WILHELM PENZOLD, O HANOVER, GERMAY, ASSIGNOR T0 WIDERSTAND AKTIENr GESELLSCHAFT FR ELEKTRO-WRME-TECHNIK, OF HANOVER, GERMANY, A COM* PANY OF GERMANY.

ELECTRICAL LIQUID HEATER.

Application ined May 22,`

over, Germany. have invented certain new' and useful Improvements in Electrical Liquid Heaters, of which the followingisa specification.

This invention relates to electrical liquid heaters wherein the liquid constitutes a resistance and is applicable to water heaters or steam generators.

In order that the invention may be' more clearly understood reference will be hereinafter made 4to the accompanying drawings whereon Fig. l is a diagram illiistrating a known type ot electric heater; Fig. 2 illustrates one example of my invention in cross-section with accompanying diagram and Fig. 3 is a vertical sectional view-ot ,-Fig. 2. y,

In the concentric arrangement of two metallic cylindrical electrodes as in Fig. l and as adopted in electric Water heaters or steam generators, the current flows in a radial direction from the inner to the outer cylinder, as indicated by the dotted lines. The maximum current density and consequent maximum Voltage drop occurs on the surface or" the inner cylinder, vThe hyperbolle curve et volts per centimeter in Fig. l shows the variation ot the Voltage drop as the distance increases from the inner cylinder. These values apply where the radius or" the inner cylinder rzl cm., the ratio ot the radius of the outer cylinder, r2,

r to the radius of the inner cylinder, 7:5

efficiency of the heater depends on the characteristics of the volt per cin, curve.

It is well known that in electric steam generators having concentric electrodes,

overloading causes momentary vaporization ot the liquid close to the inner electrode, transforming the steam `generator into a'n intcrrupter similar in principle to the Nehiielt and Simon interrupter.

li' lt represents the resistance or 1 cc. of

1922. Serial No. 562,731.

water, the output transformed into heat in this Volume of water is represented by the formula vol ts per cin2 The curve of watts per ccm. in Fig l represents this value where RzlOOO ohms. rlhe vratio of the output in ccm. at the inner electrode to the output at the outer electrode is equivalent to to l, that is, to thesquare of the ratio of the radii.

The formation ot steam bubbles further reduces the efficiency. The bubbles of course form in much greater quantity against the inner cylinder owing to the greater watts per ccm. and by decreasing the cross-section involve-increased current density and consequent increased voltage drop and decreased eiiiciency. For these reasons the concentric arrangement must not be run at too high a load.

The present invention has for its object to overcome the drawbacks of the concentric arrangement and for this purpose the surtace of the outer cylinder is equal or approximately equal to that ot the inner cylinder so that the current density is the same at both electrodes. This may be ei?- Liected by covering part oi the surface off the outer electrode with insulation.

Fig. 2 shows one example in which a` is the inner electrode t', 52, Z13 and )i are the surfaces of the outer cylinder actually availn able to the current and equal in area to a. rllhe rest or the surface ot the outer vcylinder is covered with nsi'ilation c', c2, c3, and o1. By this arrangement the current is distributed as indicated in dotted lines in The curves 'for Volts per cm. and watts per ccm. are also shown for a Voltage diti'erence ot 500 volts with 0:1 ein. and

2 T7: 5 ein.

A comparison or the two diagrams shows that the maximum value of watts per ccm. in Fig. l is only reached by the arrangement according to Fig. 2 with more than twice the main current voltage. Thus the arrangement accord-ing` to Fig. 2 approxii mates the ideal condition in which the current is unitormiy distributed over thespace between the two electrodes,

In order to avoid a short circuiting effect n the current distribution, the base or ends of the boilerA may be also cov .i d with in sulation. Y

Fig. 3l illustrates a constructional form of the heater, in which the bottom e is covered by insulation f and the tubular body (l of .the boiler is closed at the top by a coverv 71:, and in which the inner electrode a is connected to a binding post h on the cover by a conducting rod g.

The insulation used for covering the surface of the electrodes also serves Simultaneously to protect the boiler from the heat.

Claims:

1. An electrical liquid heater having con centric electrodes and insulation covering 'a part of the inner surface of the outer elec` trode to leave an uncovered outer electrode surface equal or substantial-ly equal to that WILHELM PENZOLD.