US1367102A - Constant-temperature device - Google Patents

Description

J. SLEPIAN.

CONSTANT TEMPERATURE DEVlCE. APPLlCATlON HL ED JULY 10. 1918.

1,367,102. Patented Feb. 1,1921.

INVENTOR WITNESSESz' Joaeph J/zpiazz.

' XI'TORNEY UNITED STATES PATENT OFFICE.

JOSEPH SLEPIAN, F WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC 8a MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA;

CONSTANT-TEMI'ERATURE DEVICE.

Specification of Letters Patent.

Patented Feb. 1, 1921.

Application filed July 10, 1918. Serial No. 244,333.

To all whom it may concern.

Be it known that I, JOSEPH SLEPIAN, a

' citizen of the United States, and a resident of Wilkinsburg, in'the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Constant.

.Temperatu-re Devices, of which the followin is.a specification.

y invention relates to constant-temperature devices and particularly to methods of,

and means for maintaining the temperature of, one junction of a thermo-couple constant. One object of my inventlon is to provide means whereby the junction of a thermocouple may be subjected to a salt mixture that has a definite melting point to thereby maintain the thermo-couple at a constant temperature, irrespective'of the change 1n heating of the mixture or the ambient temperature "to which-it is subjected.

A further object of my inventlon is to provide a device of the above-indicated character that shall be simple and inexpensive to construct and effective in its operation. I

In practising my invention, I provide 'a salt mixture that becomes conductive at a definite temperature. The junction of a thermo-couple, or other devicejthat is to be maintained at a constant. temperature, is disposed adjacent the surface of the mixture and the mixture is heated by an alternating current. Since the mixture has a definite melting point and is of such substances that its composition remains un changed, irrespective of the melting caused by heating of the same, the thermo-couple will be maintained at a constant temperature in a film of the melted mixture. The mixture may be, for example, a hydrated salt having an indifferent point in itssolubility curve such as zinc sulfate (7H O). This is a solid below 50 C. but becomes a saturated solution at 50 C. Above this temperature it becomes a Water solution of zinc sulfate. Therefore, if, at 50 C. heat is removed from the solution, the zinc salt precipitates out but it crystallizes with 7 molecules of water to produce the solid salt to have the same composition as the solution. Thus, since the remaining solution retains the same'composition, irrespective of the heat applied thereto, the temperature remains at 50 until the whole mixture has been converted into a solid zinc tion 23% by weight.

sulfate, with 7 molecules of water of crystallization.

The single figure of the accompanying drawing 1s a diagrammatic view of a constant-temperature device embodying my inventlon.

A source of alternating current 1 is operatively connected, through a transformer 2, to a circuit 3'comprising a resistor 4 and a conductor 5. A salt mixture 6 is disposed around the conductor 5 and one junction .7 of a thermo-couple is disposed adjacent the inner surface of the mixture 6 and the conductor 5. A The mixture 6 is composed of a salt having a definite melting point, at which temperature it becomes a conductor. Thus, when the current traversing the conductor 5 so heats the mixture 6 as to cause the same to melt in a film around the conductor 5, the current will fiow through two parallel paths, one through the conductor 5 and the other through the melted film of the mixture. The junction 7 of the thermo-couple w ll be disposed inthe melted film of the mlxture and, if the mixture is of the roper materials, the junction will be mai tained at a constant temperature, irrespective of changes in current traversing the conductor 5. That is, since the composition of the mixture does not change, irrespective of the precipitation caused by the application of heat, the temperature will be maintained at in which the latter salt occurs in propor- Above 171.5 (1, this such as bismuth-chlorid and ferric-chlorid mixture is a fluid and, on cooling, both the bismuth-chlorid and the ferric-chlorid precipitate out but always remains in the proportion of 23% ferric-chlorid. Thus, since the composition of the remaining mixture does not change when heat is withdrawn, the mixture will remain at 171.5 C. until the whole mass has become solid.

Another class of substances suitable for this purpose is a solution of hydrated salt having an indiiferent point-in its temperature solubility curve. An example of this class, of substance is a solution of zinc sulfate which is saturated at 50 C. Above 50 (1., it is a water solution of zinc sulfate. If heat is removed from such a substance at 50 (3., the zinc salt precipitates out but crystallizes with 7 molecules of wa. ter to cause the solid salt to have the, same composition as the original solution; Thus, as .the salt precipitates out, the remaining solution has the same composition, and, therefore, since the melting point of a salt having such a composition is always 50 C., the temperature of the device, such as the junction 7 of the thermo-couple, is maintained constant until the whole solution has been converted into a solid zinc sulfate, with 7 molecules of water of crystallization.

Another material that may be used for the mixture 6 is a eutectic mixture of a solid crystallizing with two different lproportions of water in a water solution. 11 example of such a mixture is a solution of ferricchlorid in water havin the proportion of 17 gram molecules of erric-chlorid to 100 gram molecules of water. Such a'mixture -1s.a true solution above 35 0., and, when heat is removed therefrom at 35 0., a solid precipitate forms which is a mixture of ferric-chlorid (7H O) and ferric chlorid (5H O) in such proportions as to produce the same total composition as the original solution. Thus, when part of such a solution solidifies, the remaining composition is unchanged and the temperature of the same will remain at 35 C. until the whole is converted into a solid mixture of two hydrated iron salts.

The essential featureof my invention is that the device, the temperature of which is to be maintained constant, is subjected to a salt that, when heated, does not change its composition but which melts at a definite temperature to become a conductor, and thus, lrrespective of the amount of melting caused by the heating, its composition is al ways the same and is maintained at a defin1 te temperature. That is, the temperature w1ll remain at the melting point of the salt, Irrespective of a change in .the heating current, or the ambient temperature to which it 1s subjected.

y 111VeI1t1011 is not limited .to the specific ,salt solutions described, as various substances may be employed without departing from the spirit and scope of my invention, as set forth in the appended claims.

I claim as my invention:

1. A constant temperaturedevice comprisin heating means, and a substance that is a apted to become conducting at a definite temperature and have a constant composition, the means to "be maintained at a constant-temperature being disposed adjacent the heating means and the substance.

ent point 'in its temperature-solubility curve disposed adjacent the heating member to maintain constant the temperature of a thermo-couple disposed adjacent the surface of the said mixture.

4:. A constant-temperature device comprising a conductor, electric means for'heating the conductor, a body of hydrated salt having an indifferent point in-its temperature solubility curve surrounding the conductor and adapted to become a conductor at a definite temperature to maintain at that temperature a thermo-couple disposed adjacent the surface of the conductor.

5. The method of maintaining a device at a constant temperature which consists in heating a zinc sulfate (71-1 0) mixture and placing the device adjacent the surface of the mixture.

6. The method of maintaining a constant temperature which consists in heating a body of hydrated salt having an indifferent point in its temperature solubility curve with an electric current. 1

7. The method of maintaining a' device at a constant temperature which consists in electrically heating a conductor and a body disposed therearound that is adapted to melt and become a conductor at a predetermined temperature and disposing the device in a fihn of the body at the surface thereof.-

8. A constant-temperature device comprising a hydrated salt mixture having an indifferent point in its temperature-solubility curve, and means for heating the same,

sald mixture being such that, when heat is crystallizes with water that the solid salt has the same composition as the original mixture.

9. A constant-temperature device comprising a hydrated salt mixture having an indifferent point in its temperature-solubility curve, and means for heating the same, said mixture being such that, when heat is removed, the salt precipitates out and so crystallizes with water that the solid salt has the same composition as the original mixture to maintain the temperature thereof constant, irrespective of the heat applied thereto.

-10. The method of maintaining a device at a constant temperature which consists in heating -a body, that is adapted to melt and become a conductor having the same composition as the original body, and disposing the device in a film of the melted body.

11. The method of maintaining a device 5 at a constant temperature, irrespective of thevheat applied thereto, which consists in disposing the device in a salt mixture that melts at a predetermined temperature and maintains a constant composition.

10 12. The method of malntaining a constant point in its which consists in heating a rated salt having an indifferent temperature-solubility curve to the temperature of that point and then supplying heat energy to compensate for the radiation losses.

In testimony whereof, I have hereunto subscribed b 1918.

y name this 22nd day of June,

JOSEPH SLEPIAN.

Images