US1247998A - Adiabatic calorimeter. - Google Patents

Description

S. W. FARB. ADMBATIC CALGRNIETER. APPLICATION FILED AUG-4, 1916. mem@ Nw 2"?, 19N;

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ADIABATIC CALORIMETER.

To aU whom t may concern.'

Be it known that l, SAMUEL lV. PARK, a citizen of the United States, residing at Urbana, in the county of Champaign and State of Illinois, have invented certain new and useful Improvements in Adiabatic Calorimeters; and lf do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to calori1n eters and more particularly to a calorimeter in which an adiabatic condition may be maintained about the combustion system during` the progress of the reaction therein.

ln usual calorimetric practice the combustion'is eifected in a closed combustion chamber which is immersed in a body of liquid. As the increase in temperature of this liquid is one of the factors to be measured in computing the heat of the reaction, it is necessary, in order that greatest precision may be obtained, to prevent any transfer of heat between the liquid and the surrounding medium during the time the measurements are being taken.

ln the apparatus of the present invention this adiabatic condition for the system is effectively maintained by apparatus of simple construction.

In the preferred embodiment a jacket completely incloses the liquid which surrounds the combustion chamber', and means are provided for circulating through this jacket a liquid, the temperature of which may be easily raised or lowered or held at any exact point at will. The apparatus, while permitting` a high degree of accuracy in measurements, is simple in construction and easy to manipulate. These features are important in calcrimeters intended for industrial use Other objects and advantages of the present invention willbe made clear by the following detailed description which is to be taken in conjunction with the accompanying drawings, wherein Figure 1 is a front elevation of the instrument principally in section; and

Fig. 2 is a side elevation ofthe same, pring cipally in'section.

Referring to thedrawings, wherein simi- Speccaton of Letters Patent. Patmlgdl NQV 27, jpgjjljjo Application filed August 4, 1916.

Serial No. 1 13,087.

lar reference characters refer to similar parts throughout the views thereof, 10 represents a combustion chamber, or bomb, as it is technically called. This bomb may be of any desired construction adapted for the purpose in hand and includes essentially a cup portion 11 and a cover portion clamped together by means of an outer collar 12.

Upon the bottom of the cup of the bomb are formed lugs 15 which, when the bomb is in place in the oval can or receptacle 16, surround a boss 17 formed in the base of the can. This can holds the liquid, the rise in temperature of which is used as one factor in computing the heat of the reaction occurring in the bomb. For obtaining this measurement, a thermometer 18 is mounted upon the cover of the instrument in a manner that will hereinafter appear. rlrhe liquid within the can 16 should be stirred during the course of observations and hence a stirrer 19 mounted upon the cover of the apparatus provided.

Surrounding can 16 is a water-jacket having` al dead air chamber 2O wherein can 1G Vis mounted on insulating .supports 21. The water-jacket has inner and outer walls Q2 and 23 respectively and a top plate 24 to which the inner wall 22 is attached at its upper edge. rheouter wall is attached to the top plate by a plurality of lugs 25 but between these lugs it terminates a short distance below the plate to form outlets 26 through which water may overflow into a pocket or channel surrounding the jacket and formed by a wall 27 attached to the outer surface of the wall 23. The pocket is provided with a drain pipe 28 wliicheX- tends through the outer casing 29 of the apparatus. This outer casing Q9 is preferably constructed of heat-insulating material and is somewhat larger than the jacket so that there is an air paco between the wall 23 of the latter and the inside of the casing.

The upper edge of the casing 2f) is formed with a recess 30 within which the top plate 24C is adapted to flt, thus insuring that the jacket and the parts carried thereby are properly centered in the casing Since the jacket is attached to the plate Q4, all of the parts of the apparatus are suspended within the casing and can be readily removed, although in practice the jacket will be kept in place since there are various other parts of the instrument connected thereto and which must be removed in order to take out the jacket.

The cover of thc apparatus comprises a chamber formed with side, top and bottom walls 35, 36 and 87 respectively. The top and side walls are covered by an outer casing 38 of the same material as the casing 29 and having a recess at 39 corresponding to the recess 30 to tit over the outer edge of plate 24.

` Attached to the bottom 37 of the cover and passing through apertures in the top plate 24 are a discharge tube 40 and a supply tube 41, the latter having a sliding tit about a tube 42 leading from a centrifugal pump 43 mounted on the base of the jacket. The lower end of tube 41 has an inverted V-shaped cut within which tits a corresponding wedge-shaped projection on a collar 42 which is attached to tube 42. The tubes 41 and 42 forni a pivotabout which the cover may be swung and the above construction constitutes a lifting device to automatically raise the cover as it is swung about the pivot tubes. While a slight lifting of the cover just at the start may be necessary it involves little or no inconvenience in operation but may be avoided by using a corresponding lifting arrangement comprising a wedgeshaped projection on the upper edge of casing 29 adapted to cooperate with an inverted V-shaped cut on the lower edge of the cover to produce the initial lifting thereof.

The pump 43 is driven by a shaft 44 mounted in a sleeve 45 having a water-tight fit with the wall of the jacket. A bearing nut 46, a driving pulley 47 and a bearing bracket 48 are provided. Upon the shaft are blades 49 to produce circulation of liquid through the jacket when the shaft is rotated. Although a centrifugal pump for raising the liquid from the bottom of the jacket to the chamber in the cover has been illustrated, other devices for performing this function may be used.

The stirrer 19 for the vliquid within can 16 is mounted upon the cover in the manner shown in Fig. 2. A tube 55 forms an open passage through the chamber of the cover. The stirrer is mounted in a plug 56 set Within the passage and having a ledge adapted to rest upon the top of thc cover. Pref erably the plug 56 should be made of heatinsulating material in order to lessen the possibility of a transfer of heat by conduction through the shaft of the stirrer. To further attain this object the shaft of the stirrer may be made in two sections connected together by a coupling 56 of heatinsulating material such as hard rubber. To give the coupling increased strength the hard rubber may be incased in brass tubing.

A pulley 57 is placed on the shaft for driving the same.

The thermometer 18 which extends within can 16 and a second thermometer 60 extending into the jacket are arranged to passV of a set-screw 66. Rod 64 should extend` through top plate 24 and into chamber 2O ay distance at least equal to the distance the thermometers extend into the liquids in the can and jacket respectively. The reason for.` this arrangement is to prevent the possi-A bility of breaking the thermometers when the cover is removed to obtain access to the combustion bomb and can 16. vWhen the cover is swung about the tube 42 as a pivot the automatic lifting device 42 raises the` cover sutliciently to bring tube 40 out of the hole in plate 24 through which it passes when the cover is 1n place, provided of course that the stirrer 19 be rst removed. by taking out plug 56 and the thermometers.

be raised so that rod 64 clears plate 24. The plug 56 is extended below the bottom 37 of the cover plate to avoid danger of bending the stem of the stirrer in case the user of the calorimeter forgets to remove the plug and stirrer before attempting to swing the cover plate. Under these conditions the bottom of the plug would hit the inner wall 22 of the jacket to remind the user that the plug should be removed. In practice the height to which it is necessary to raise the cover before it may be swung out of its normal position need be only about a quarter of an inch or less.-

Water or other liquid for the jacket is supplied through pipes and 71, one of which leads to a source of hot water supply and the other to cold water. The iiow of water through these pipes is controlled by stop cocks 72 and 73. Pipes 70 and 71 are connected by rubber tubings 74 and 7 5 to pipes 7 6 and 77 leading through the casing 29 and connected to the outer wall 23 of the jacket at points opposite the end of shaft 44. It is advisable to make these water supply tribes in sections connected together by a rubber tubing in order to prevent the conduction of heat from the wall of the jacket through the Ymetal of the pipes. For the same reason it is advisable to use a piece of rubber tubing 78 on the overiiow pipe 28.

In a bomb of the character illustrated, means must be provided for starting the chemical reaction within the bomb. In the present case it is done by an electric current,

1 ,2 497,993 gli the circuit for 'which may be traced from a terminal mounted on but insulated from the covel of the bomb. From this terminal a conductor S1 leads over the edge of can 16, through a water-tight gland 82 inserted in the inner wall 22 of the jacket, through one of the outlets 26 at the top of the jacket and through the casing 29 to a binding post 83. The other side of the circuit is formed through the metal of the bomb, it being understood that there is a spark gap, heating coil or other means for igniting the charge, suitably connected between the terminal 80 and the metal of the bomb, when the cover of the bomb is in place. Since the bomb is resting upon the bottom ot can 16 the circuit may be completed from the latter' to the inner wall 22 of the jacket by means of a spring-actuated contact device 81. To the metallic coverplate 2i .is attached by means of a binding post 85 a conductor 86 which passes through one of the outlets 26 and then through the casing 29 to a binding post 87. The binding posts may be connected to any appropriate Source of current with switch for Controlling the circuit thereof.

The method of using` the apparatus described above is as follows. The parts of the bomb are clamped together after the proper materials have been placed therein and the bomb is set in place in can 16 which, for convenience, may have been removed from the apparatus. A known quantity of water of a temperature slightly below that of the surrounding air is placed in the can. There should be sufficient water to cover the bomb completely. The can is then placed in chamber 20, the cover of the apparatus being swung aside to permit this operation. The cover is then swung into place and lowered to rest upon top plate 24. The thermometers are then lowered into position and the stirrer 19 lowered into the water and started to agitate the water. Water is then admitted to the jacket through pipes 70 and 71. Shaft 47 is start-ed to cause a steady circulation through the jacket and some of the water is lifted by pump t3 to lill the hollow cover to the level of outlet pipe 4:0. By proper manipulation of valves 72 and Z3 the temperature of. the water in the jacketing system may be made equal to that of the water in the calorimetric system, the two thermometers being conveniently placed for simultaneous readings. After equality of the two temperatures is insured the charge in the bomb is ignited and as the combustion proceeds the temperature of the water in can 16 rises. By allowing more hot water to enter the jacket the temperature of the water therein may be Caused to increase at substantially the same rate as does the temperature of the water in can 16. There can thus be no external transfer of heat to or from the water in can 16, and the increase in temperature of this water is due solely to the heat generated by the reaction taking place within the bomb.

Instead or' the procedure outlined above may in some cases be found sulicient to bring the water in the jacket to an initial temperature about equal to that which the water in the can will attain, a rough computation serving to give the approximate increase of temperature that will occur when the reaction takes place.

After the observations have been completed the pump 113 is stopped, the thermometers are raised out of the liquids, thc stirrer 19 is removed and the cover is rotated and at the same time lifted by the cam action of 42. Liquid in the chamber of the cover will drain out through pipes 4l, 42 and pump 43, causing an overflow into the surrounding channel 27 and out through the drain pipe 28. When the cover has been swung aside, can 16 and the bomb contained therein may be removed and the wire 81 disconnected from the bomb.

It has been found in practice to be entirely possible to maintain the temperature of the water in the jacket so near to the temperature of the water surrounding the bomb that no gain or loss of heat in the interior system can be detected. It may be stated in this connection that if the jacketing water is within 0.1 or 0.2 degrees ot the water in can 16 it will be impossible to detect any radiation losses over a reasonably short period of time, say ten or fifteen minutes.

It will be understood that many changes may be made in the construction oit an apparatus embodying the invention, without departing from the principle thereof.

I claim:

1. A calorimeter comprising in combination means adapted to hold a combustion bomb and submerging liquid, means completely enveloping said lirst named means and adapted to contain a liquid, and means for controlling the temperature of the liquid in said surrounding means, substantially as described.

2. A calorimeter comprising in combination means adapted to hold a combustion bomb and submerging liquid, means constituting a chamber completely enveloping said iirst named means and adapted to contain a liquid, and means for controlling the temperature of the liquid in said enveloping chamber, substantially as described.

3. A calorimeter comprising in combination means adapted to hold a combustion bomb and submerging liquid, means constituting a chamber completely enveloping said irst named means and adapted to contain a liquid, and means for maintaining a circulation of liquid throughout said enveloping chamber, substantially as described.

4l. A calorimeter comprising in combination means adapted to hold a combustion bomb and submerging liquid, means constituting a chamber completely enveloping said first named means and adapted to contain a liquid, means for maintaining a circulation of liquid throughout said enveloping chamber, and means for controlling the temperature of the liquid in said enveloping chamber, substantially as described.

5. A calorimeter comprising in combination means adapted to hold a combustion bomb and submerging liquid, means constituting a chamber completely enveloping said first named means and adapted to contain a liquid, means for maintaining a circulation of liquid throughout said enveloping chamber, means for controlling the temperature of the liquid in said enveloping chamber, and means for measuring the .temperature of both of the liquids, substantially as described.

6. A calorimeter comprising in combination a receptacle adapted to hold a combustion bomb and a submerging liquid, a jacket around said receptacle, a hollow member above said receptacle and having communication with said jacket, and means for admitting liquid at diiierent temperatures into said jacket and member at will, substantially as described.

7. A calorimeter comprising in combination a receptacle adapted to hold a combustion bomb and a submerging liquid, a jacket around said receptacle, a hollow member above said receptacle and having communication with said jacket, means for admitting liquid at different temperatures into said jacket and member at will, and means for maintaining a` circulation of liquid throughout said jacket and member, substantially as described.

8. A calorimeter comprising in combination a receptacle adapted to hold a combustion bomb and a submerging liquid, a jacket around said receptacle and composed of inner and outer walls and a top plate, a hollow cover having communication with said jacket, and means for admitting liquid of diiierent temperatures into said jacket and cover at will, substantially as described.

9. A calorimeter comprising in combination a receptacle adapted to hold a combustion bomb and a submerging liquid, a jacket around said receptacle and composed of inner and outer walls and a top plate, a hollow cover having communication with said jacket, means for admit-ting liquid of different temperatures into said jacket and cover at will, and means for maintaining a circulation of liquid throughout said jacket and cover, substantially as described.

Lampes 10. A calorimeter comprising in combination a receptacle adapted to hold a combustion bomb and a submerging liquid, a jacket around said receptacle and composed of inner and outer walls and a top plate, a hollow detachable cover having communication with said jacket, and means for admitting liquid of different temperatures into said jacket and cover at will, substantially as described.

11. A calorimeter comprising in combination a receptacle adapted to hold a combustion bomb and submerging liquid, a jacket around said receptacle, means for admitting liquid at different temperatures into said jacket at will, means for maintaining a circulation of liquid throughout said jacket, and means for measuring the temperatures oi the liquids in said receptacle and said jacket, substantially as described.

12. A calorimeter comprising in combination a receptacle adapted to hold a combustion bomb and submerging liquid, a jacket around said receptacle and composed of inner and outer walls and a top plate, a hollow cover having communication with said jacket, means for admitting liquid at diiferent temperatures into said jacket at will, and a plurality of thermometers mounted on said cover and normally extending through the same into said receptacle and'said jacket, substantially as described.

13. A calorimeter comprising in combination a receptacle adapted to hold a combustion bomb Yand submerging liquid, a jacket around said receptacle, a cover having a chamber communicating with said jacket, a plurality of thermometers mounted on said cover and normally extending through the same into said receptacle and jacket, and means for maintaining a circulation of liquid throughout said Vjacket and cover and over the bulb of the thermometer eX- tending within said jacket, substantially as described.

14. A calorimeter comprising inl combina-- tion a receptacle adapted to hold a combustion bomb and submerging liquid, a jacket around said receptacle, a coverrhaving a chamber communicating with said jacket, means for maintaining a circulation of liquid throughout said jacket and cover, and means for maintaining lthe temperatures of the submerging liquid and the jacket liquid substantially the same, substantially as described.

15. A calorimeter comprising in combination a receptacle adapted to hold a combustion bomb and a submerging liquid, a jacket around said receptacle, a hollow cover above said receptacle and jacket, means between said cover and said jacket serving as a communicating passage between the two and also as a pivot about which the cover rio may be rotated to remove the same from its normal position, substantially as described.

16. A calorimeter comprising in combination a receptacle adapted to hold a combustion bomb and a submerging liquid, a jacket around said receptacle, a hollow cover above so formed as to maintain a predetermined.

depth of liquid in said cover, substantially as described.

l?. A calorimeter comprising, in combination, a receptacle adapted to hold a combustion bomb and submerging liquid, a jacket surrounding said receptacle, a hollow member above said receptacle and having communication with said jacket, thermometers adapted to extend through said hollow member and within said receptacle and jacket, and an adjustable support for said thermometers mounted on said hollow member; substantially as described.

18., A calorimeter comprising in combination a receptacle adapted to hold a combustion bomb and submerging liquid, a jacket around said receptacle, a cover having a chamber communicating with said jacket, thermometers mounted upon said cover and adapted to extend within said receptacle and jacket, and an adjustable support for sai/l thermometers including means for preventingl rotation of said covers when said thermometers extend below said cover, substantiallj7 as described.

19. A calorimeter comprising in combination a receptacle adapted to hold a combustion bomb and submerging liquid, a jacket around said receptacle and composed of inner and outer walls and a top plate, a cover having` a chamber communicating with said jacket, thermometers mounted upon said cover and adapted to extend within said receptacle and said jacket, and an adjustable support for said thermometers comprising a rod extending through said cover and said top plate when said thermometers extend below said cover to prevent rotation of said cover at such times, and means for maintaining said rod in any desired position of adjustment, substantially as described.

20. A calorimeter comprising in combination a receptacle adapted to hold a combustion bomb and a submerging liquid, a jacket around said receptacle composed of inner and outer walls and a top plate to which said walls are attached, a cover formed with a chamber therein, a tube communicating with said chamber and extending downwardly through said plate into said jacket,

a second tube slidably connected to said first named tube and attached to the wall oi said jacket, means within said second tube for raising liquid upwardly therethrough and means for controlling the temperature ot the liquid in said jacket, substantially as described. i

2l. A calorimeter comprising in combination a receptacle adapted to hold a combustion bomb and a submerging liquid, a j acket around said receptacle composed of inner and outer walls and a top plate to which said walls are attached, a cover formed with a chamber therein, a tube communicating with said chamber and extending downwardly through said plate into said jacket, a second tube slidably connected to said first named tube and attached to the wall of said jacket, means within said second tube for raising liquid up iardly therethrough, means for controlling the temperature of the liquid in said jacket, and an overflow tube communicating with said chamber and extendingl downwardly through said top plate between the walls of said jacket, substantially as described.

A calorimeter comprising` in combination a receptacle adapted to hold a combustion bomb and submerging liquid, a jacket around said receptacle composed of inner and outer walls and a top plate to which said walls are attached, a cover formed with a chamber therein, a tube communicating with said chamber and extending downwardly through said plate into said acket, a tube telescopically associated with said first named tube and attached to a wall of said jacket, means within said second tube for raising liquid upwardly therethrough, and means for maintaining a circulation of liquid toward said raising means, substantially as described.

A. calorimeter comprising in combination a receptacle adapted to hold a combustion bomb and a submerging liquid, a acket around said receptacle and composed of inner and outer walls and a top plate to which said walls are attached, the outer wall being formed with an outlet adjacent said top plate, a pocket upon the outside of the said jacket, a cover formed with a chamber therein, passageways between said chamber and said jacket, means for admitting liquid at different temperatures to said jacket, and means for draining liquid from said pocket, substantially as described.

24. The method of protecting a calorimeter system from transfer of heat externally, which consists in surrounding the system with a circulating liquid and maintaining said liquid at a temperature approximating the external temperature or' said system.

25. A calorimeter comprising in combination a receptacle adapted to hold a combustion bomb and a submerging liquid, a acket around said receptacle, a hollow cover above said receptacle and jacket, means between said cover and said jacket serving as a communicating passage between the two and also as a pivot about which the cover may Copies of this patent may be obtained for five cents each, by addressing the be' rotated to remove the same from vits normal position, and means associated with said first-named means for automatically lifting the cover as it '1s rotated; substantially as described.

In testimony whereof I aiX my sgnature.

SAMUEL W. PARE.

Commissioner of Patents.

Washington, D. C.

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