IMPROVEMENTS IN THERMO- ELECTRIC PILES AND GENERATORS
Year: 1878

page_text: LETTERS PATENT to Jean Marie Edouard Sudre, of Boulevard Saint Denis,
1, at Paris, Gentleman, for the Invention of "IMPROVEMENTS IN THERMO-
ELECTRIC PILES AND GENERATORS."
Sealed the 20th May 1879, and dated the 9th December 1878.
COMPLETE SPECIFICATION filed by the said Jean Marie Edouard Sudre at
the Office of the Commissioners of Patents on the 9th December 1878.
JEAN MARIE EDOUARD SUDRE, of Boulevard Saint Denis, 1, at Paris, Gentleman.
"IMPROVEMENTS IN THERMO-ELECTRIC PILES AND GENERATORS."
My Invention has for its object an improved system of thermo-electric piles and
generators founded on the following characteristic points:-
1st. The construction of thermo-electric couples having a feeble interior resistance
under a very small volume, their disposition in chains as hereafter described for
facilitating their assemblage and mounting.
2nd. The maintenance of the difference of temperature necessary between the
two solderings of each couple by placing these couples between two surfaces with
which they are electrically isolated.
3rd. One of the said surfaces is designed to heat the warm solderings, and makes
part of a metallic system which I call "collector," which has the effect of collecting
and storing the caloric from the source of heat, and communicating it to the couples
across the isolated bed.
4th. The other surface is designed to cool the cold weldings, and makes part of a
metallic system (with the employment of liquids sometimes) which I call "diffusor,"
and which has for its object to draw and collect the caloric from the couples either
for diffusing it into its nature, or for transporting it by means of a medium to a
point where it is desired to utilise it.
And in order that my said Invention may be well understood I shall now proceed
more particularly to describe the same, and for that purpose shall refer to the

page_text: accompanying Sheet of Drawings, like letters of reference indicating corresponding
parts in all the Figures.
In the construction of thermo-electric couples and chains an isolated thermo-
electric couple is ordinarily composed of a prism in metal or alloy casting A, Fig. 1,
and of a polar plate of iron, copper, German-silver, or other suitable metal, soldered
to each of its extremities. The plates do not ordinarily interfere in the slightest
with the electric force obtained, and it is the bar A, such as that of antimony and
zine, which contributes in a great measure to the total effect produced. When it is
desired to use two metals or energetic alloys, of which the effects are combined, and
which are easily fusible, such as the bismuth and antimony, the couple is formed
then of two bars A and B (Fig. 2), which are jointed together by a cross-bar T,
which binds them, and is soldered to each of them. To this second arrangement
are also applied the procedures hereafter described.
The total resistance of a couple is composed,-
1st. Of the resistance of the plate C (Fig. 1); 2nd Of the resistance of the bar A,
ordinarily formed of alloys sufficiently resistant; 3rd. Of a particular resistance at
he points of contact or solderings a, a', of the plates and of the bar.
Resistance of the Plate.-The metallic plate should be of a metal sufficiently con-
ductive, such as copper, iron, German-silver, or other composition, and sufficiently
large and thick for presenting but a feeble resistance. It should have also the
least length or unfolding possible, all conditions which are realised in the following
description:-
L
L
Resistance of the Bar-To obtain for the bar A very little resistance under a
small volume I take as my starting point the formula R=K in which is a
specific coefficient for the matter employed; L, the length of the couple; and S, its
section. As the resistance depends upon the relation one should in diminishing
these two dimensions into the same relation diminish the volume of the couple
without increasing its resistance. The length of the couple depends equally upon
the differences of temperature employed, and is the greater as these differences are
greater. For the differences of temperature from 10 to 120 degrees I give to the
couples a length of 10 to 12 millemeters, and for those of 300 degrees a length
varying between twenty and thirty millemeters.
Resistance of the Solderings. In a short couple also the formation of the products
of the points of contact or solderings is of the highest importance. The junction
should be made so that the plate should be in contact with the points of the whole
section of the bar, and at the same time penetrate to a very little depth in the bar,
so as not to diminish too much the electro-motor force of the couple; for the
difference of temperature really effective is that of the temperatures of the two
solderings, and this difference diminishes in degree as the plates penetrating deeper
into the bars approach one another. To obtain this double object the extremity of
the plates is cut in the form of a comb (Fig. 3), the teeth of which are twisted upon
themselves (Fig. 4) in such a manner as to present a helicoidal surface, which holds
them, so to say, screwed into the metal. This cut portion is placed in the cast
mould at the end of the bar in such a manner that the teeth are embedded in the
casting. These teeth should be considered as the ramifications of the plate which
are distributed on the whole section of the bar.
In the case where the couple is composed of two cast bars (Fig. 2) the cross-bar T
will carry the comb to each extremity. Having thus explained the condition to be
realized, and my means of realisation in the construction of a thermo-electric couple,
I proceed by a system of coupling the said bars, as that of a single cast of metal or
alloy, the bars cast simultaneously are found bound and coupled together, and
forming a flexible thermo-electric chain, easy to handle, facilitating the mounting
of the apparatus, and realising the minimum of resistance desired.
Fig. 5. represents the plate cut and bent twice at the time of using it for the

page_text: formation of the couple. The centre G is fixed, and the two bent parts p and pl
cut and twisted as described.
On each side of the full part G of the plate is pasted with silicate of soda, or fixed
by any other means, a thin plate of isolating substance capable of resisting the
contact of the cast metal, such as paper of amianthus, or asbestus, inica, terra-cotta,
or other suitable material.
The mould (Fig. 6) is composed of a foot C, of two side pieces A, B, maintained
parallel by two cross pieces K and K', of a cover D carrying a longitudinal furrow
pierced with holes d equal in number to the number of couples contained.
The plates prepared as before described are placed in the mould between the two.
side pieces A, B, as is represented in Fig. 6. Then placing the cover D on the top
and running in the cast alloy, the interior of the mould is filled, and the bent
extremities of the plates are bedded in the cast metal. In taking the mould to
pieces there is taken out a chain represented in Fig. 7, composed of as many elements
as the length permits, which can be varied at pleasure, and this chain is found to
be a thermo-electric battery, the extremities of which, P and N, are the poles. The
paper of amianthus or asbestus may be used in various ways; it may be cut into
strips, folded, and bent, as Fig. 7 (bis) indicates. The prepared plates are then
placed in the slits a, a, a, a, and the whole being placed in the mould the cast of the
metal will be in the form of a chain, analogous to that of the preceding case.
manner.
In the case represented in Fig. 2, where the thermo-electric couple-has-been-
formed of two cast bars A, B, the formation of-the-chain will be in an analogous
First of all-the-bars of metal the less fusible, those A for example, will
-be cast separately, and will carry at each extremity a cross bar T, cut into a comb,
as before described. Thus prepared this first series of bars should be of the same
form as the bent plate (see Fig. 5), and will be conveniently placed in the moulds
in lieu of the said plates. The fusion of the second metal B in binding the open
extremities of the cross-bars will form a thermo-electric chain composed of couples
similar to those described in Fig. 2.
ARRANGEMENT AND COLLECTION OF THE CHAINS IN BATTERY.
Two metallic plates A and B, Fig. 8, which are represented as planes, but which
may be cylindrical or curved, are covered on one of their faces by a thin layer of
isolating substance of electricity. This substance should be either a layer of enamel
applied on the metal, or a leaf of mica if the temperature of the plate is elevated;
or it may be a varnish, a leaf of vulcanised india-rubber, a thin gummy or oily
stuff if the temperatures employed are less elevated. Between these two isolated
surfaces is placed one or more thermo-electric chains in such a manner that the
extremities of the couples which constitute these chains press upon the isolating
surfaces. When more chains are used side by side between the two same plates
they should be returned each time in this manner that the opposite poles of two
contiguous chains are found side by side; they may be easily coupled in tension.
Fig. 8 (bis) shews this arrangement, and the manner in which the current flows
according to the directions of the arrows. The contiguous chains should be also
isolated the one from the other, by an isolating band a, a, a, 'Fig. 8 (bis), of
amianthus or asbestus paper, mica, india-rubber, or other material. In the case
where the surfaces A and B are curved the space which is formed between two
contiguous chains should be filled up with isolating matter, such as amianthus or
asbestus paste, to avoid the lateral loss of caloric; all the elements of the chains
are electrically isolated by the isolating thickness of the plates, but they are not
isolated calorically, so that if by any means the plate A (Fig. 8) is maintained at a
high temperature, and plate B at a lower temperature, the caloric will flow across
the isolated beds and penetrate the couples, across which it will continue its course
from one soldering to the other. The difference of temperature between A and B
will be within very little of the temperature between the solderings of the couples.
As long as A and B keep their respective temperatures a thermo-electric current

page_text: When the plate A, Fig. 8, is heated either by steam which is condensed by its
surface, or by a hot liquid in circulation, the quantity of heat which should be
yielded to the plate A upon its surface is great enough to furnish for the consump-
tion of the battery. The plate A in this case is its proper "collector," but it cannot
be so if the apparatus is heated by heated gases or air. The simple circulation of
the heated gases upon the plate A is not sufficient to maintain it at the desired
temperature, and the plate receives its heat by a metallic system which presents a
very large surface to the gases in motion, and causes them to travel over a course
sufficiently long so that they abandon the greater part of their caloric.
<<
These collectors" may vary in form and dimensions according to the case, but
they are always collected into one combination of metallic pieces ordinarily of cast
iron, so that they present by their combination a series of flues, through which cir-
culate the gases, and are formed with ribs, as desired, for directing the flow of the
caloric against the plate A, Fig. 8.
Fig. 9 represents a "collector" for the large apparatuses designed to collect the heat
of the burnt air from a fire grate or from heated gases, kilns, or other source. It is
composed of ribs in cast iron of a form A, Fig. 9 (bis), so that when assembled upon
one circumference similar to the staves of a cask they form a cylinder leaving
between them some flues d, d, to allow for the passage of the gases.
Fig. 9 gives the horizontal and vertical sections of this "collector." The heated
gases or heated air arrive by a chimney M, which is in the centre of the "collector,"
and at the top of the chimney the lid G forces the gases to separate into the first
series d of the flues, through which they descend to remount into the second series d
and thence into the exit chimney.
This double action of the gases ascending and descending has the effect of making
uniform the temperature of the cast iron ribs, the collective surface of which should
be as large as possible, at least five or six times larger than the surface represented:
by the total section of the couples employed; or instead of being composed of a
large number of collected pieces the "collector "may be cast all in one piece by means
of a suitable model and core boxes, or in two, three, or four parts collected together
as described.
When in place of a double movement of ascending and descending of the hot
gases it is desired to employ only a single movement ascending or descending, the
wings t of the rib A, Fig. 9 (bis) should be suppressed. The gases rising to the centre
are divided and forced to pass into the flues by a cylinder or disc k, Fig. 10, placed
at a convenient height.
it may be
The "collector" may assume any other form besides the circular form;
rectangular, the ribs being then parallel instead of convergent, and cast several
together, or separately to be joined aftewards.

page_text: rature almost the same as that of the liquid. In this case, which is the simpler, the
plate B serves as its own proper "diffusor," and will be the side of a vessel or
recipient of variable form adapted to the form of a thermo-electric battery. If the
battery is circular the "diffusor" should be formed of cylindrical segments; if
rectangular, of parallelopipeds. The water arrives cold by the bottom part, and
departs tepid at the upper part. When a current of water continuous and sufficient
is employed this arrangement is simple; thus, as it is represented in Fig. 11, the
water arrives cold, escaping tepid or warm, and can be either diffused into its
nature or utilized for every domestic or industrial use, but if one does not use a
current of water the caloric which the plate B acquires must be diffused into the
air, and this result can be obtained in the two following manners :—
1ST. "DIFFUSOR" WITH LIQUID MEDIUM.
If according to the preceding system at a higher level than that of the water-
boxes described is placed a receipient K, Fig. 12, at a convenient point, and if this
recipient is put in communication by sufficiently large pipes with the cooling
boxes B, the whole system being filled either with water or an uncongelable mixture
of water and glycerine, or with any other suitable liquid, the whole of this arrange-
ment will constitute a system of liquid by circulation, following the variation of
density of the liquid consequent upon its heating and cooling. The recipient k
should have a sufficient surface to diffuse by the radiance or contact of the air the
caloric which the automatical circulation of the liquid brings to it. This system
can be combined with heating apparatuses for the circulation of the warm air to be
used for the heating of buildings.
When no liquid medium is used the "diffusor" should be made directly into the
air by the conductibility of metals. Fig. 13 illustrates a simple arrangement for
the purpose. The plate B is made of very thick metal, ordinarily of cast zine; it
carries soldered thereto or let into the casting large plates of red copper or other
metal sufficiently conductive, drawn together one to the other, and representing a
considerably diffusing surface. Between these plates are set up some currents of air,
which take up the caloric. The radiance of the plates contributes also to the pro-
duction of the same effect. Fig. 13 represents the disperser as the general arrange-
ment of the system.
A is a rib of cast iron forming part of a "collector" before described. d, d, are
the isolating beds; T, chain or collection of thermo-electric chains; B, zinc plate ;
and L plates of diffusing conner
Having now described the different elements, of which the reunion and combi-
nation constitute my apparatuses, I proceed to give some examples of the batteries
which can be realised thereby.
APPARATUSES FOR HEATING BY STEAM.
Figs. 14 represent in perspective elevation and section respectively a thermo-
electric battery heated by steam. The apparatus is constituted by the superposition
of frames pressed between two pieces of cast iron by a series of bolts which cross it.
Between these frames are equally pressed ten copper plates p, p, p, which serve to
divide the box thus formed into nine compartments. Four of these compartments
T, T, T, T, are filled by a series of thermo-electric chains, such as those seen in
Fig. 8, compressed between two plates p, p, from which they are isolated, as also
the frames which surround them, by some sheets of india-rubber.

page_text: The extremities of this system of thermo-electric coupled chains terminate by
some lengthened polar appendages which jut out across the frame from which they
are isolated to give up the current. Two of these compartments v, v, are designed
to receive the steam at any pressure whatsoever, and the three others E, E, E, a
current of escaped water. Between the frame and the two plates which form this
compartment is a joint of india-rubber, which renders the compartment water-tight.
These frames are provided with elbow pipes, to which are jointed pipes, serving
some as the inlet to the steam, others the inlet of the water, and others for the
outlet of the water and the expulsion of the condensed steam. Each frame carries
thus two elbow pipes, one for the arrival, the other for the outlet. In the water
boxes are placed two ribs, which serve to intertie the plates p, p, so as to lengthen
the course taken by the water.
This apparatus realizes therefore four thermo-electric batteries on my system, of
which the poles abut on bars carried by a small board fixed on the apparatus.
The dimensions and number of compartments to the apparatus above described
may be varied at pleasure. This apparatus may therefore be considered as a specimen
of all those which can be constructed upon the principles before described and designed
to work by the heat of steam.
It. is to he remarked that the steam can be replaced by a warm liquid in
circulation without anything essential being changed in the arrangement of the
Fig 15 represents an apparatus heated by hot gases, and more ordinarily by the
heated air proceeding from a special fire-grate arranged on every side, consuming
any combustible whatsoever.
G, collector of the system described in Fig. 9.
T, T, thermo-electric chains applied against the collector, from which they are
electrically isolated; these chains are bound between them by solderings or other
connection. The current rises and descends alternately through two contiguous
chains.
The apparatus may consist of either a single or several distinct batteries. P, P, P,"
represent the water boxes of cylindrical sections, which are applied upon the
'exterior surface of the thermo-electric chains with which they are electrically isolated;
these boxes constitute the water "diffusor" as represented in Fig. 11, or liquid
medium as before described in Fig. 12.
This liquid "diffusor" can be replaced by a dry "diffusor" of the kind described
in Fig: 13.
Fig. 16 represents a portable form of my apparatus, the "collector" of which is a
plate of cast iron provided with collective ribs.
The thermo-electric system is in T. The "diffusor" is a box plate through which
passes a current of water, entering at A and escaping at B.
a vertical
The apparatus is provided with a handle or hilt R to facilitate its displacement;
it works ordinarily upon a horizontal grate, but it can work in
position. One can replace the dry "diffusor" and use vertically two or more of theso
models, one in front of the other.
Having now described and particularly ascertained the nature of my said Inven-
tion and the manner in which the same is or may be used or carried into effect, I
would observe in conclusion that what I. claim as my Invention is,―
1. The construction and arrangement of thermo-electric chains, composed of
couples, the resistance of which has been reduced to a minimum, substantially as
herein before described and illustrated by the accompanying Drawing.
2. The combination and arrangement of the said chains or thermo-electric couples
with two metallic plates, the two surfaces of which are covered by an isolating
layer, and form part of two metallic systems, of which one collects and stores the
caloric, whilst the other draws off and diffuses the caloric, substantially as herein-
before described, and illustrated by the accompanying Drawing.

page_text: 3. The combination and arrangement for binding, coupling, and isolating the said
thermo-electric chains when several are mounted side by side between the two afore-
said plates for constituting a thermo-electric battery, substantially as hereinbefore
described, and illustrated by the accompanying Drawing.
4. The application and use of the "collector" and "diffusor" to any description
of thermo-electric piles, so as to maintain the necessary difference of temperature
between the extremities of the couples without lateral waste of the caloric, sub-
stantially as hereinbefore described.
5. The application and use of the different systems of " collector" and "diffusor"
to the thermo-electric piles, substantially as hereinbefore described, and illustrated
by the accompanying Drawing.
6. The construction and use of the different arrangements of thermo-electric
batteries, to all of which the above points are applied, substantially as hereinbefore
described, and illustrated by the accompanying Drawing.
İn witness whereof, I, the said Jean Marie Edouard Sudre, have here-
unto set my hand and seal, this Ninth day of December, in the year of
our Lord 1878
Witness,
ALBERT CAIEN,
Civil Engineer, of Boulevard St. Denis, 1,
at Paris.
J. M. E. SUDRE. (L.S.)