US375243A - Thermo-electric generator - Google Patents

Description

(No Model.)

E; G. AOHESON.

THBRMO ELECTRIC GENERATOR. No. 375,243. Patented. Dec. 20, 1887.

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I Nrrnn 'rn'rns EDWARD e. Aonnson, or PITTSBURG, rENNsYLvANIA.

THERMO-ELECTRIC GENERATOR.

SPECIFICATION forming part of Letters Patent No. 315,243, dated December 20, 1887.

Application filed September 2, 1887. Serial No. 248,632. (No model.) i

p which the following is aspecification.

In thernio electric generators heretofore constructed it has been customary to place acouple or a series of couples of conductors separated in the thermoelectric series as much as possible in contact with each other, to heat one portion of the couple or couples artificially and to allow the other portions to cool either by radiation or to be cooled by the application of some cooling agent. The difference of temperature between the two portions thus obtained was necessarily very low, and

the electro-motive force of the current yielded by an apparatus of this kind was necessarily small.

In all attempts which have been made. to produce electric currents with a combination of solids and liquids it has been found that, although the currents obtained may, at the first moment of heating one of the conductors, be of considerable strength,it rapidly falls, owing tothe'formation of gases upon the surfaces of the solids and to other peculiarities in the investing fluid, as set forth by Faraday.

It is the object of my invention to construct a thermoelectric generator in such a manner as to avoid these objections and to increase and maintain the difference of temperature between the two thermoelectric elements, and consequently to increase the electro-motive force of the current generated. I accomplish this object by separating the two thermoelectric elements bya inoving conducting-fluid and by applying heat directly to one of the elements, whereby the temperature of the other element can never rise above the boil- 'ing-point of the conducting-fluid which separates it from the first. It will now be understood that, while one of the elements to which' the heat is directly applied may beraised to a; comparatively high temperature, the other ele ment will be comparatively cool, and that consequently a current of considerable ten sion will be produced in the exterior circuit of such couple. lhe movement at the sursired degree.

faces ofcontact between solids and fluid will prevent the accumulation of gases on their surfaces, and consequently avoid a drop in the strength of the current. This is the fundamental idea of my invention, and in the following detailed description of the same referenceis made to the accompanying drawings, in which several of the numerous forms which my invention may assume are illustrated. My inventiomhowev'er, is not confined, either generically or specifically, to the apparatus herein shown and described, but it includes and embraces the mode'of operation therein involved.

In the drawings, Figure 1 represents a side elevation, partly in section, of one form of my apparatus; Fig. 2, a cross-section of a detail of construction, Fig.3, a perspective view, partly in section, of a modified form; and Fig.

4, a sectional elevation of another form of my I improved thermoelectric generator.

Referring now more particularly to Figs.1

and 2, I have there shown a tube or pipe, A, of some conducting material, and a rod, B, of eitherthe same or anoyier kind of conducting material, passing cenrally through the tube, and held separated from the walls of the same by a tightly-fitting washer, P, at one end and an annular web,

refractory insulating material, whichis also a poor conductorof heat, like asb'estus, clay, 8m, Near one end of the tube A an ifopening is produced in thesame, which comm nicat'es, by a tube, D, or otherwise, with a source of water or other conducting-liquid, so that the water coming into the tube A, filling the same and discharging at the annular web I. Thus it will be seen that the rod B will be surrounded on all sides by the conducting-fluid employed, but will otherwise be insulated from tube A.

C is a gas-pipe placed parallel below tube A, and a number of gas-jets emerging from burners c c c a 0 will heat tube A to any do A will in'turn heat the con ducting-fluid within the same, which in turn will impart its heat to the rod B; but it is a known law of physics that fluiis having a surface exposedto the atmosphere can never be heated beyond a tem- I, at the other end. Both the washer and the annular web are made of some from this source aforesaid will pass .The heat thus imparted to tube sumed in the production of steam or vapor,

perature at which said fluid boils, for every additional increment of heat is at once conwhich, when the surface of the fluid is open to the atmosphere, will escape.

In the apparatus here shown, if vin place of the annular web I a tight washer were used, the fluid filling the tube A would be heated up to its boiling-point, but could never be heated beyond that point, and the temperature of rod B would therefore reach its maximum when the boiling-point of the fluid is reached, while the tube A may be, and in the nature of things-will be, much hotter without imparting additional heat to the rod B; but in the construction herein shown, where the fluid entering the tube A by the pipe I) is allowed to discharge at V, the temperature which said fluid can attain will be necessarily much lower than that of the boiling-point of the same, and the difference of temperature betweentube A and rod B will therefore be very great. If, now, the rod and the tube be connected by an external circuit, X, a current of considerable tension will discharge into the same and will be maintained as long as the difi'erence of temperature is maintained. The moving liquid carries with it the steam or gas developed, preventing the drop of electrical potential due to the adhesion of the gases to the surfaces of the elements which might otherwise take place. It will be clear that any number of thermo-electrie generators constructed upon this principle may be connected in series, and will then furnish a current of any desired tenmen.

In Fig. 3 a modified form of my apparatus is shown. In place of tube A, as shown in Fig. 1, I here employ a trough, A, of conducting material, and upon insulating-ledges O O, of refractory material, is placed a cover, B, of the same or another kind of conducting material of which the trough is made. The tube 1) communicates with the space inclosed by the trough and cover, and the conductingfluid employed enters the trough by said tube in the same manner as indicated in Fig. 1, and said fluid is allowed to discharge at one end of the trough, while the other end is hermetically sealed by refractory insulating material in the same manner in which tube A in Fig. 1 is closed by washer P. The heat in this instance is applied directly to the bottom of trough A. The conducting-fluid is thereby heated and imparts its heat to cover B, the temperature of which can, as will now be understood, never be higher than that of the conducting-fluid, but will ordinarily be lower than that on account of its exposed upper radiatingsurface.

Another modification is shown in Fig. 4. Here there is a vessel, T, of any suitable material, which is. filled or partly filled with a conducting-fluid. A tube, S, passing through the center of the vessel and rising above the same, is open at both ends, and is surrounded by another wider tube, K, separated from tube gas-burner, G, or any other source of heat is placed under the vessel T, with its flame passing into tube S, heating the same to any desired extent, while, as will be understood, tube K will be maintained at a much lower'temperature, governed by the boiling-point of the conducting-fluid employed. The current generated is utilized in the external circuit .X, as in the constructions hcreinbefore described. In this form of apparatus the heatgfrom the bottom of the vessel will pass in a great measure between the two tubes S and K, causing the cooler portions of the fluid from the surface to pass down toward the bottom to replace the displaced other portions. Thus a continuous upward current of fluid will be maintained within this annular space between the two tubes S and K.

ductors suitable to the construction of my apparatus such as stand on the same or on different scales of the thermoelectric tension series, and as a fluid conductor any one having a comparatively low boiling-point maybe employed .with advantage; nor do I confine myself to the particular means for establish ing current of condueting-fluidbetween the thermo-electric elements, since it is of no consequence how such current is established and maintained, if used at all.

Having now fully described my invention,- what I claim is- 1. The method of producing a difference of electrical potential between two solid conduct- 'ors, which consists in heating one of them directly and conveying the heat from the, same to the other bya moving fluid conductor, substantially as described.

2. The method of producing a'diflerenee of electrical potential between two solid conductors, which consists in heating one of them to any desired degree and maintaining the tem-- perature of the other at or below the boilingtemperature of a moving conducting fluid, substantially as described.

3. The method of generating a thermo-electric current, which consists in applying heat directly to one of the thermo-electric elements and by passing a current of a conducting-fluid between the same and the other thermo-electric element, substantially as described.

4. A thermoelectric battery consisting, essentially, of two thermoelectric elements separated from each other by a moving conductingfluid, and a source of heat applied to one of said elements, substantially as described.

5. In a thermoelectric battery, the combination of a thermoelectric element and a t source of heatdact-ing direlctly npoili the same scribing witnesses.

with a secon thermo-e ectric e ement immersed in a moving fluid conductor and sepa- EDWARD ACHESON 5 rated from the first element by said'fluid con- Witnesses: ductor, substantially as described. GEO. F. MCCOMBS, In testimony whereof Ihave signed my name M. F. CASSIDY.

0 this specification in the presence of two sub-

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