US2026423A - Constant temperature device - Google Patents

Description

Dec. 31, 1935. M, FIENE 2,026,423

' CONSTANT TEMPERATURE DEVICE Filed Sept. 27, 1933- 2 Sheets-Sheet l f Inventor:

Mar'dJs E. I- lene,

His Attorney.

Dec. v I M. Y I I I I:

CONSTANT TEMPERATURE DEVICEI' Filed Sept. 27, 19 'g's V /d3 r/M; 7 I IHVGFIIT O";

Marcus E; Y-"iene,

' I -Ii s Atton-neg Patented Dec. 31, 1935 consran'r TEMPERATURE navroa Marcus E. Fiene, Ballston Lake, N. Y., assignor to General v Electric Company,

New York a corporation of Application September 27, 1933, Serial No. 691,262

22 Claims. (Cl. 236-1) My invention relates to constant temperature devices, and it has for its object the provision of improved method and means for providing and holding predetermined constant temperatures.

This invention has general application, but it is particularly useful in those applications where it is imperative that the temperature be held at a predetermined fixed value, such as in radio frequency'control systems wherein a piezo crystal is used.

I base my temperature control on the principle that the density of a saturatedvapor is definitely correlated with the temperature; 1. e., at a given density, a saturated vapor can have only one temperature. In order,ftherefore,jto main tain a constant temperature; it is essential to maintain a constant density of the vapor and to keep it inthe saturated condition. I substantially efiect the first requirement by confining a determined weight of a selected vaporizable fluid in a vessel or container of fixed volume and applying suiiicient heat to vaporize substantially all of the free liquid. In order to maintain substantially all of the'fluid at'the saturation point, I apply heat to the fluid in such a manner that super-heating of the vapor within the vessel cannot occur. The amount of fluid that is introduced into the vessel is such that when all of the free liquid is vaporized the density of the vapor, and hence its temperature will have the desired value.

In order to vary the temperature, I change the density of the controlling vapor while holding it at the saturation point. In one form of my invention, I accomplish this by removingpreselected quantities of the container." .In another form, I change the density of the vapor by varying its volume.

The vessel or container in one form of my invention is provided-with a reentrant portion C011:- stituting a chamberwhich is used to receive the object whose temperature isto be controlled, such as the above-mentioned piezo crystal A relatively long vapor tube communicates with thecontainer through its bottom wall. This tube communicates with a vaporizer which is provided with suitable means for applying heat to it so as to vaporize the fluid within the vaporizer that exists in the liquid phase.

The control'devlce, therefore, in brief, consists in a vaporizer, a container which in effect functions somewhat as a condenser and a tube con necting the vaporizer with the container, all arranged into a closed system.

I shown my invention in one eiiective fluid from the.

12 connecting the vaporizer wall I5.

In one form of my invention, suitable means are "providedfor removing a portion ofeifective fluid from the closed "system so as to vary the density of the vapor and hence, the temperature setting of the device. In 'another form, of my invention, the density is varied so as'to' adjust the temperature setting by changing the volume of the container or condenser.

For a more complete understanding of my'invention, reference'should be had to the accompanying drawings, in which Fig. 1 is a vertical sectional view of a temperature control device embodying my invention; Fig. 2 is a vertical elevation illustrating a plurality of temperature control devices, each in Fig. 1, and providedwith common heating means for their Vaporizers; Fig. 3 is.a fragmenarranged as is the device shown 15 tary sectional elevation illustrating the temperature control device shown in Fig. 1, but provided with means arranged in ac cordance with 'myinvention for varying the density of the controlling. fluid; Fig. 4 is a sectional elevation of a tempera ture control device illustrating means arranged in accordance with a modified form of my in.- ventionfor varying the'density of the controlling fluid; Fig. 5 is a fragmentary sectional elevation illustrating still difierent means for varying the density of. the controlling fluid arranged in.ac.- cordance with my invention; Fig. 6 is a fragmentary view of a portion of the device of Fig. 5; Fig. 7 is a sectional elevation of a modified form of my invention; and Fig. 8' is an elevation mainly in section of still a further modified form of my invention. l v Referring more particularly to Fig. 1, I have form ,as applied to a temperature control device comprising a container or condenser 10, a vaporizer Hand a tube with the condenser into a closed fluid system of fixed volume. This tube 12, as shown, communicates with the condenser through its bottom wall 13. This wall preferably and as shown will have aninverted conicalshape tapering downwardly to its center, where it communicates with the tube. I2. The vaporizer II should have a very small volume as compared with the volume of the closed system.

Thus, it should preferably not be more than 0.1% v

of the total volume.

The chamber II for receiving the object (not shown) ,whose temperature is to be controlledispositioned within the condenser 10. This chamber, as shown, is arranged substantially centrally of the condenser and is supported from its upper This wall It is provided with a cen- 2 trally arranged aperture it through which the chamber I4 is inserted into the condenser. The chamber Il may be secured to the upper wall It in any suitable manner, as by brazing or welding. Preferably, the bottom wall Ila of the chamber It will taper downwardly to its center, as clearly showninFig.1. Thepurposeforthiswillbe pointed out hereinafter in greaterdetail.

The article whose temperature is to be controlled is inserted into the chamber throu hits upper open end.

The outer walls of the container It and the vapor tube l2 preferably will be covered with a layer of insulating material ll. Any suitable insulating material may bowed to form the layer II, but I prefer to use mineral wool for this pur- The insulating layer l1 covering the top wall II is provided with an aperture l'la through whichaccesscanbehadtothe chamber It. This aperture will normally be covered by means of any suitable cover member (not shown).

Heat is applied to the'vaporizer by means or a heating element It, which as shown is formed into convolutions that surround the vaporizer. This heating element is provided with a suitable source of electrical supply 2.. It will be understood that steam or any other suitable heating agent may be used to heat the vaporizer I I.

If desired, the heating element It may be controlled by means of a temperature responsive device 2| so asto avoid overheating. While any suitable temperature control device may be used,

-I prefer to use a control device of the type described and'claimed in United States patent to A. H. Simmons, No. 1,743,073, dated January 7, 1930. Briefly. this temperature control device oomprise'sa iii-metallic bar 22 which has one end fixed and its other end free to move in response to changes-in temperature. This latter end bears, on one arm of an inverted U-shaped spring 23, the other arm of which bears on a flxed pivot 24.

'I'hebase of the spring carries a switch arm 2' which operates a switch 28 ,to open and close the energizing circuit for the heater It. The temperature control device is arranged so that the 22' is in thermal relation with the heatelement is. As fully pointed out in the Simons patent? when the temperature of the heatj in: element, and hence of the vaporizer, reaches a predetermined maximum value, the bimetallic 7 bar 12 will function to open the switch 28, whereas whenthe temperature of the heating element,

that is of the vaporizer, reaches a predetermined low value, the bimetallic bar will close the switch 28 so 'arto reenergize the heating element. In this ,manner. ,the temperature control device functions to maintain a temperature in the vaporizer sufllciently above the temperature of the,

saturated vapor to keep all of the free liquid vaporized, and yetnot so high as to cause inJury to the vaporizer-or heating element. a I A- quantity of a suitable vaporizable fluid. such as sulphur dioxide or difluor dichlor methane, or anyother suitable fluid, is introduced into the container It. This fluid may be passed into the container through a suitable tube 21 entering the through its upper wall. It is preferable te substantially evacuate the container before th'e fluid is introduced. This may be accomplished by attaching a suitable vacuum apparatus to the tube 21. After the container has been evacuated and the selected fluid placed within it, the upper end of the tube 21 will be sealed.

The amount of fluid introduced into the system will be such that when all of the free liquid is and by condensation in the chamber ll.

vaporized and maintained just at the saturation point, its density and hence, its temperature, will have the desired value; the selection of the fluid to be used, of course, depends upon the temperature-density characteristic of the fluid. 5 In other words, the choice of the fluid and the weight of the fluid used must be such that when all of the vapor has been evaporated and is maintained in a saturated condition, the fluid must have the density corresponding to the temperature at which it is desired to hold the controlled object. The choice of fluid also depends somewhat on the degree of temperature control desired. If very close control is required, a liquid is selected having a high vapor density at the is desired temperature because it has been found that in general a higher vapor density will give a closer temperature control. On the other hand,

if very close temperature control is not required it may be advantageous to use a vapor having go a lower density, because usually low vapor pressures are associated with low vapor densities, and hence, the device can be designed for a lower operating pressure.

The fluid that is chosen, of course, must be one gs which will not attack the ordinary materials available for use for making the condenser, the vaporizer H and the vapor tube l2.

In the operation of the system, the object whose temperature is to be controlled. is placed within so the vessel It and the heating element 18 is energized. Initially some of the fluid will exist in the liquid phase, the free liquid collecting in the vaporizer II. It will be understood that the free liquid is that. portion of the fluid in the liquid as phase which is free to flow to the vaporizer. When'heat is applied to the vaporizer, a transfer of heat will take place between the vaporizer and the container It by evaporation in the vaporizer.

46 The heating element It functions to raise the temperature of the vaporizer to a value above that at which all of the free liquid will be vaporized. As heat is applied and the liquid in the vaporizer is vaporized, the temperature and pres- 45 sure of the fluid within the chamber or condenser 10 increases until all of the free liquid in the vaporizer has been vaporized, when a condition of temperature equilibrium is reached. If a small mass of thevapor within, the chamber l0 conso denses because of loss of heat through the walls of the chamber, or for any other reason, it will flow back to the vaporizer where it will again be vaporized. The fluid thus vaporized will pass through the tube It to the condenser and in doso ing so will convey sufllcient energy from the vaporizer to the condenser to maintain the condition of temperature equilibrium in the condenser. Actually there will be a'constant transfer of heat from the vaporizerto the condenser in this man- I her. That is, fluid will constantlycondense on the walls of the chambers Ill and it due to heat loss through the walls and will flow to .the vaporizer through the tube II. This liquid which gravitates to the vaporizer will be vaporized imes mediately and passed back to the chamber I I as a saturated vapor. It is for this reason that the chambers l0 and H are provided with downwardly tapering bottom walls which function to direct the condensate directly to the tube It.

In order to maintain the fluid within the condenser vaporized and yet at the same time prevent superheating of the vapor, I have thermally isolated the vaporizer II from the condenser in such a way that substantially no heat will pass 16 a,o2c,4as

has a height of approximately 10 inches and a y from: the vaporizer to the condenser either by conduction or by convection, but can only pass by the flow of saturated vapor.. I

In order to accomplish this, I make the tube l2 offa metal having a relatively low thermal con- I ductivity, such as steel or Monel metal. The tube I2 in addition to this has a relatively small crosssection so as to inhibit the transferiof heat from the vaporizer to the condenser by convection currents from the super-heated zone in the vaporizer. The diameter of the tube should preferably be 8 mm. or less. It has been found that if the diameter is this small there will be no transfer of heat by convection of the superheated vaporfrom the vaporizer to the condenser.; By reason of the foregoing construction, and: because vaporized fluid itself is a poor conductor of heat, the vapor in the condenser II cannot possibly become superheated. I

This arrangement of the vapor tube imposes a limitation on the maximum rate of flow of the saturated vapor from the vaporizer to the condenser. Because of this, it a relatively large condenser is used it is preifir able'to use a plurality of vapor tubes connecting the condenser with the vaporizer.

Actually, it has been found that the expansion of vapor within the vaporizer due to the superheat will increase somewhatthe' denslty of the vapor in the condenser, but this increase will be very slight because of the fact that the volume of this super-heated vapor in the vaporizer is only about 0.1% of the total volume. Actual tests have demonstrated that the temperature ofthe vapor in the condensing chamber varies only about0.001 per degree of variation in the temperature of the vapor in the vaporizer.

Because of this, it is not essential that the heating element l8 be controlled to maintain a substantially constant temperature in the vaporizer.

'Variations in the wattage input will vary the super-heat in the condenser, but this variation,

"as previously pointed out, haspractically no effect on the condenser temperature, that is, the temperature in the vessel l4. In other words, my device can utilize the heat generated at a source of varying temperature and make this heat available at a constant temperature- It will be observed that my control device of Fig. 1 functions to vaporize virtually all of a flxed weight of a vaporizable fluid which iswithin a container of substantially constant volume and maintains the fluid inthe saturated condition. Thus, it maintains at a definite value the density of a saturated vapor. As is well understood under such conditions, the temperature of the fluid in the condenser will be held at a substantially constant value and hence, the objector device within the chamber l4 will be held at a substantially constant temperature. 7

As previously pointed out, not quite'all of the fluid will be in the vapor phase when, the system has reached an equilibrium temperature. Heat leakage through the insulation layer I will cause a slow condensation on the-container walls and because of this there will be a substantially constant flow of liquid into the vaporizer I l where it will be vaporized immediately. Changes in the ambient temperature will change the rate of liquid condensation and return to the vaporizer and hence will affect the amount of fluid existing in the liquid phase butit has been found that this efl'ect' is so small that it will not affect the temperature appreciably. Thus, with the control device shown in Fig. 1 where the condenser diameter of approximately 9 inches, and where sulphur dioxide is used as the controlling fluid, it has been found that this does not cause a variaq tion in the temperature of the condenser, chamber of more than 0.01 per degree variation in the ambient temperature. This variationcan be reducedbyincreasingthe volume of the condenser.

It is to be noted, ofcourse, that my device will 7 not function if the ambient'temperature is higher 10 than the temperature desired in the chamber i4,

nor will itfunction when the vaporizer temperature is below the temperature desired in the chamber l4.

Itwill be understood that while the vapor tube 1 i2 will be formed ofa material having arelatively low heat conductlvity'. it ispreferable to form the vaporizer ll of a material having a relatively good conductivity, "such as copper. The

, copper vaporizer I I may be secured to the vapor tube 12 in any suitable manner, as by welding, or

brazing.

, In Fig. 2 I have illustrated a plurallty'of'control devices" arranged in identically the same fashion as the temperaturefcontroi device of. Fig. 1, but provided with a common heatingunitfor their vaporizers. As shown in this figure, apair of temperature control devices and 3| are provided with vaporizers 32and 33 respectively. The vaporizers 32 and 3 3 are arranged in a posi- 30 tion relatively close to 'each other and are surrounded by convolutions of a suitable heating element 34 which, as shown, is arranged toapply heat to both of the vaporizers at the same time.

The heating element 34. is energized from a suit- 35 able electrical'supplysource 351 .The energization of the heating element is controlledby means of a suitable temperature control device 36f which may have any suitable form, but which preferably will be constructed as is the temperature control device 2| of Fig.1. g u

The advantage of this arrangement is that substantially constant temperatures of widely different values can be maintained at the same time in the two control devices 30 and 3| by means of only one heating element. For example, it might be desirable to design a cabinet having two compartments held at different temperatures for use of pathological laboratories. For suchape plicatlons, the temperatures for example may be 37.5" C. and C. This arrangement, therefore, is quite economical in its operation. It will be understood, of course, that the controlling fluids which willprovide. widely different temperatures can be used in the two control devices. I 55 Moreover, it will be understood that three 'or four more control devices may be arranged to be controlled by a single heating element, as shown in Fig. 2.

In Fig. 3, I have shown means for varying the 00 densityand hence the temperature held by' t'he control device by changing the volume of the condenser. As shown in Fig. 3, the condenser 40 encloses a chamber 4| in which the object whose temperature isto be controlled is placed. The 05 condenser 40 and thechamber' 4! are arranged in substantially the'same fashion as arethe' condenser l0 and chamber l4 of Fig. 1. Moreover, it will be understood that the condenser 40 communicates with a vaporizer by v tube all arranged in substantially the same fashion as are the corresponding elements of Fig. 1.

means of a fluid side wall of the condenser so as to project into the condenser. The side walls and inner end of the bellows are completely closed, that is, they are impervious to leakage of fluids, and the inner end is mounted in the aperture with a fluid-tight joint between the bellows and the condenser. The bellows may, be expanded and contracted by means of an adjusting rod 44 connected at its inner end to the inner end wall of the bellows and passed through the bellows to the exterior or the condenser, as shown in Fig. 3. The adjusting rod is threaded at its outer end and on this threaded portion is received an adjusting lmob 45. The knob is restrained from longitudinal movement on the rod 44 by means or a plate 45 which functions to support the knob 45 and which, as shown, is provided with an aperture 41 which is received in a peripheral groove or recess 48 provided in the knob.

It will be obvious that by turning the knob 45, the position of the rod 44 and hence the position of the bellows can be changed. To expand the bellows it is merely necessary to turn the knob 45 so as to move the rod 44 inwardly of the condenser, whilst to contract the bellows it is merely necessary to turn the knob 45 in the opposite direction so as to retract the rod 44.

In other words, the eflective volume of the controlling fluid within the closed system can be adjusted merely by turning the knob 45. Of course, the density oi the fluid is changed when the volume of the chamber 40 is varied. If the volume is increased by contracting the bellows, the density will be decreased. On the other hand, it the volume is reduced by expanding the bellows, the density will be increased. As is well understood by those skilled in the art, when the density of a saturated vapor is changed, the equilibrium temperature of the vapor will change with it. More specifically, the equilibrium temperature increases with increase in the density, and decreases when the density is decreased. In this manner the temperature held by the control device can be controlled merely by turning the knob 45.

I have shown in Fig. 4 a modified form of my invention wherein a different means is provided for adjusting the density of the fluid, and hence the temperature setting of the control device. In the form shown in Fig. 4 I effect this adjustment by renderings. portion of the fluid ineflectivc.

The temperature control device shown in Fig. 4 comprises a condenser 50, a vaporizer and a vapor tube 52 connecting the condenser and the vaporizer in to a closed system. These members are arranged in substantially the same fashion as are the corresponding elements shown in Fig. l. The condenser 50 receives a chamber 53 similar to the chamber l4 oi. Fig. 1. The vaporizer 5| is heated by means oi! an electrical heating element 54 which is energized from a suitable source of electrical supply 55 and is controlled by a temperature control device 56.

The bottom wall 51 of the condenser 50, however, is not of conical form, as is the bottom wall I3 01 Fig. 1. On the contrary, the bottom wall 51 is formed as a plane surface. And the tube 52 of Fig. 4, rather than communicating with the condenser 50 through the central portion of the bottom wall communicates with it at a point relatively close to a side wall of the condenser, as clearly shown in Fig. 4.

In this arrangement of Fig. 4, it is contemplated that the condenser 50 will be supported in a position inclined to the vertical, rather than in a vertical position, as is the condenser lb of Fig. 1. It is also contemplated that the condenser will be supported by means 01 some suitable means whereby its position can be adjusted. For this purpose, the condenser 50 is supported in 5 a clamping collar 59 surrounding the condenser 50. It is preferable to interpose a suitable metallic bushing 50 between thecollar 59 and the insulating layer 5| that covers the condenser. The collar 59 is carried by means oi a rigid supporting frame 62. The condenser 50 may be rotated in the collar 59 about its longitudinal axis to any suitable position where it will be locked or secured by the ring.

In the operation of this form oi! the invention, it will be observed that when the heater 54 is energized it will vaporize substantially all of the liquid in the system, with the exception of that which is trapped in a pool 63 in the lower corner of the condenser. The level of this pool is determined by the position of the mouth of the tube 52. In other words, liquid can collect in this pool until the liquid level rises to the mouth 01 the tube 52, whereupon any more liquid flowing to the pool will overflow into the tube 52 and thence to the vaporizer.

It will be obvious that the quantity of liquid that will collect in the pool 53 before it overflows to the tube 52 will depend upon the position of the condenser 50. It the condenser 50 be rotated so as to raise the position of the mouth oi! the tube 52, more liquid will'be allowed to collect in the pool 63.

In this manner, the weight of eflective fluid within the closed system can be controlled so as to control the density of the vapor and hence, the equilibrium temperature that is held within the chamber 53. If the effective weight of the fluid be reduced by increasing the volume of the liquid pool 63, the density of the vapor will be re- 4 duced, and as a result, the temperature maintained in the chamber 53 will be reduced. 0n the other hand, if the weight of the effective fluid within the system be increased by decreasing the size of the liquid pool 63, the density will be increased and a higher temperature will be held in the chamber 53.

The weight of eflective fluid can be controlled over a relatively wide range of values, and as a result, the temperature setting of the device can be controlled over a relatively wide temperature range. As a matter of fact, by suitably varying the weight of the efiective fluid, the temperature can be adjusted through a range having substantially the ambient temperature as the lower limit and the critical temperature oi the fluid as the upper limit.

In Fig. 5, I have shown apparatus of modified form for changing the effective weight of fluid within the system. In Fig. 5, the condenser 65 is or substantially the same form as is the condenser lflof Fig. 1. Thus, it is provided with a bottom wall 55 that has the shape of an inverted cone. In the center of this bottom wall is an aperture 55a which communicates with a vapor tube 51 which in .turn communicates with a vaporlzer 68. The vaporizer 58 is heated by means 01 a suitable heating element 10. The vapor which is generated by evaporation of liquid in the vaporizer 68 instead of being directed back 70 into the condenser through the pipe 61 is conducted to the condenser through a separate return pipe 1| which, as shown in Fig. 5, communicates with the condenser through its side wall at a point adjacent the bottom wall 55. It will be 15' The pipe 61. as shown, does not'entcrthecon denser but enters a separate somewhat larger; conduit I2 which in turn communicates with the condenser through the aperture 60a. The fluid conduit 61", as shown, projects upwardly into the conduit I2 for some distance. This arrangement provides an annularspace I3 between the two conduits 6 1 and I2. This annular space functions to collect condensate gravitating from the condenser 65.

The annular space 13 communicates with an annular chamber I4 surrounding the conduit 12 through a flexible conduit member l5. 1 This member 15, as shown, has one end connected to the lower end of the annular passageway I3 and its other end connected with the bottom of the annular chamber I4. I

It will be observed that by reason of this ar-,.

rangement the condensate which collects inthe chamber I3 c'an flow directly into the chamber I4 and that the liquid levels in the two chambers I3 and I4 will be the same. Themaximum level is determined, of course, by the-height of the tube 01 above the bottom of the annularchamber I3. 4 The quantity of liquid that is allowed. to. collect inthe chambers 13 and I4 is controlled by adjusting the vertical position of the chamber 14. This chamber, as-shown, is supported forvertical movement upon a plurality of rods I6 which depend from the bottom of the wall 90. The position of the chamber I4 is adjusted by means of a. screw I1 passing through the bottom wall of -an insulatingi covering I8 provided I for the control apparatus, as clearly shown in Fig. 5. Preferably, a suitable bushing I9 willbe arranged in this insulating wall-for receiving the screw; It will be understood that by turning the screwv to move it upwardly the chamber. .14 will be'movedupwardly, which of course willcause liquid in the chambers 13 and I4 to overflowinto the conduit 61 from which itflnds its way to the evaporator 68; If the'screwbe'turnedso as topermit the annular chamber I4 tomove downwardly, more of the condensate willbe allowed to collect in the chamber before it will overflow. In thismanner, the weight of working fluid within the system iscontrolled. I f p 'The upper end of thechaniber 14 will be vented by means of, a flexibleeonduit 80' which places the upper portion of the chamber in communication with the condenser. asclea'rly shown in Fig. 5.

The ',vertical axes of the tube 6'I -and the an nular' chamber I4 preferably should be made to coincide, and preferably'the tube SI should be arranged so" that liquid will flow into ltfron'ithe annular chamber 13 along the vertical axis of the tube. To accomplish this the tube 6'Iat its'upper end'isbent inwardly so that a portion 8| of the wall will be in this axis. Within this portion a V-shaped notch 8Ia is formed so that the bottom of the V lies in the axis of the tube. r

This arrangement is important becauseit insures a practically constant volume'of trapped liquid in the chambers I3 and I4 regardless of change of position of the device away from the vertical, within limits. l

As 'previouslypointed out, the temperature maintained by my control device will varyslightly with changes in the ambient temperature.- ':Moreover. as previously pointed out, the temperature will also vary somewhat with variations in;the super-heat temperature in the vaporizer.

arrangement, it'will be observed that while the ceive theobject whose temperature isto be con- However. it maybe that in some applications a more sensitive control'is desired. ,In Fig. 7, I have shown aform. ofmyinvention which will provide a more sensitive control. In Fig. '7. this. is accomplished by envelopingthe condenserfor 5 the primary controllingfluid with an atmosphere, constituting a secondary controlling fluid. the" temperature of which is held substantially constant in accordance with ,my invention. In this temperature of the secondary fluid will change to a small degree with changes in the ambient temperature, the temperature variation of the. primary controlling fluid resulting from changes in theambient temperature will, be practically neg- 15 ligible. I

.Moreovenin this form ofthe invention, the condensers for the primary and secondary fluids are maintained at a substantially constantteim.

perature by means of a. control device arranged 20 in accordance with my invention.

Referring moreparticularly to Fig. '7, the'com denser 90 for the primary controlling. fluid, is

connectedwith a vaporizer Si by means of a tubu lar member 9i. A chamber93- is provided to re;

trolled. M The members 90, 9|, 92, and 93,are.arranged and operatein substantially the same fashion as the corresponding elements of Fig. .1. Surrounding the condenser 90 is a second condenser 94 for; receiving the secondary controlling fluid. The condenser 94 is arranged so that the secondary fluid substantially completely envelopes'the primary condenser 90. The condenser 94 is connected with a vaporizer 95 by means of a tubular-member 96.- The members 94, 95,' "and 96 are arranged and operatein substantially the same fashion as 1 the corresponding elements showninFig.1. 1 I U Preferably the tubes 92 and 90 will be provided 40 with bends 92a and 96a respectively which assist in preventing the transfer of heat by convection currents from the Vaporizers to the condensers. Preferably, the outer walls of the'condensers 9.0 and 94 and ofthe tubular members 92 and 96 will be covered with a suitable heat insulating material ,9]. It is also preferable to completely fill the space between the evaporatorswith the insulating material.

A common source of heat is provided for the vaporizers 9| and 95. This source is controlled to hold: a' substantially constant temperature by a control device 98 arranged in accordance with my invention. This control device, as shown,'c'omprisesa condenser IIIII which is connected with 1 of the condenser. Of course, fluid-tight seals will be provided between the tubes 92 and 96 and the upper wall of the condenser.

In the operation of this form of my invention, it will be understood that. the temperature control device 98 functionsto hold a substantially constant teinperature in the Vaporizers 9I and 95. Thetemperature of the super-heated vapor in the Vaporizers 9| and 95, therefore will be p actically unaffected by changes in the ambient temperature, and by variations in the temperature of the super-heated vapor in the vaporizer I0 I. This, of course, results in an extremely small temperature variation in the primary and secondary fluids in the condenser chambers 00 and 1 04 due to temperature variation in the super-heat in the vaporizer IOI.

It is necessary that the temperature in the secondary controlling fluid be somewhat lower than the temperature of the primarycontrolling fluid. It is also necessary that the temperature of the controlling fluid in the condenser chamber I00 be somewhat higher than the temperatures of the controlling fluids in the chambers 00 and 94. Thus, if the desired temperature in the chamber 93 is 65 C., the temperature held by the secondary fluid may be 50 C., while the control device will maintain say C. in the evaporators 0| and '95.

In Fig. 8 I have shown a modified form of my invention which is in the main quite similar in construction to the form shown in Fig. 5, but it has additional means for compensating for change in ambient temperature. This compensation is accomplished by varying the weight-oi! the effective fluid in the system in accordance with variations in the ambient temperature.

As shown in Fig. 8, this control device comprises a condenser I06, a vaporizer I01 connected into a closed fluid system with the'condenser I06 by means of a vapor tube I08. The tube I08 functions both to convey the condensate to the vaporizer and to return the vaporized fluid to the condenser. In other words, the return conduit II of Fig. 5 has been eliminated. The tube I08 is similar to the tubes 92, 00 and I02 of Fig. 7.

The tube I08 is connected to the condenser by a tubular member IIO, the parts being arranged to define an annular liquid trap III. The trap III communicates with an annular chamber II2 surrounding the tube II 0 by means of a flexible tube H3. The upper portion of the chamber H2 is vented by means of a flexible tubularmember Ill which connects this portion oi! the annular chamber with the condenser chamber I06, as shown in Fig. 5.

All of these parts including the tube I08, the tubular member IIO, the chamber H2 and the conduits H3 and Ill are arranged in substantially the same fashion as are the corresponding elements shown in Fig. 5.

The position of the chamber H2 is controlled by means or a suitable adjusting screw H5.

Additional means are provided for controlling the position of the chamber H2 in accordance with the changes in the ambient temperature. This additional means comprises a reservoir or bulb H6 on the exterior-of the insulating wall I" provided for the control device so that it is subject directly to changes in the ambient temperature. The reservoir IIG communicates with an expansible bellows, or accordion-like member IIO which is arranged to adjust the position of the chamber H2. The bulb or reservoir 6 and the bellows II8 are filled with a fluid which has a relatively high temperature cceflicient of expansion, such as turpentine.

The adjusting screw H5, as shown, is directly connected to move a platform or plate I20. This plate is mechanically connected to a second plate I2I by means or the bellows H8. The plate I2I in turn is connected with the chamber II2 by means of columns I22. These columns I22 are arranged to slide vertically on rods I 23 depend- 13% from the lower wall of the condenser chamber It is to be understood that the bellows II. is sufficiently rigid to prevent relative movement between the plates I20 and I2I except when the bellows is operated in response to a change in the ambient temperature. Thus, when the screw 5 I I5 is adjusted it will impart motion to the chamber IIZ through the plates I20 and I2I, the bellows II8 and the columns I22, all connected as a rigid system.

Once the screw H5 has been adjusted,,however, the plate I20 from then on remains as a fixed member. If any change occurs in the ambient temperature, the liquid in the bulb II will expand or contract, depending upon whether the temperature rises or falls, and will expand the bellows or allow it to contract, as the case may be. One end of the bellows is flxed or anchored to the fixed plate I20, while its other end is free to move the plate I2 I, and hence the member I I2.

In the operation of this form of the invention, 20 the screw II5 will be adjusted so as to adjust the temperature setting of the control device to hold a predetermined constant temperature. I! then the ambient temperature increases, the amount of liquid in the condensate fllm on the walls of 25 the condenser I05 obviously will be decreased. when the ambient temperature thus increases, the liquid in the bulb IIB will expand and the bellows will be extended so as'to lower the chamber H2. This operation will allow more or the liquid to be trapped in the chamber H2. The expansion of the liquid in the bulb IIG controls the bellows I I8 to lower the chamber II 2 sumcientlyto increase the amount of condensate collected so as to compensate for the reduced amount of liquid in the condensate film- Conversely. if the ambient temperature decreases, the liquid in the bulb causes the bellows to contract so as to elevate the chamber H2 and thereby reduce the amount of condensate that is removed from the system so as to compensate for the increased amount of liquid in the condensate fllm resulting from reduced ambient temperature.

In this manner, the bulb IIO functions to keep r the density of the vapor substantially constant and thereby maintain the temperature constant in the condenser chamber.

While I have shown particular embodiments of my invention, it will be understood, 0! course, that I do not wish to be limited thereto since many modifications may be made, and I. therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention. 55

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A temperature control device comprising a closed chamber constituting a condenser, a vaporizer remote from said condenser, a conduit 0 connecting said vaporizer with said chamber arranged to prevent the transfer of heat by conduction and convection between said vaporizer and said chamber. a vaporizable fluid within said vaporizer and condenser and means for heating said vaporizer to a temperature sufficiently high to vaporize substantially all of said fluid in said vaporizer that exists in the liquid phase.

2. A temperature control device comprising a closed chamber constituting a condenser. a va- 70 porizer in fluid communication with said condenser, a vaporizable fluid within said condenser and vaporizer, means for applying heat to said vaporizer to vaporize the fluid in said vaporizer that is lame liquid phase and means inhibiting 75 the transfer of heat by conduction and'convection from said vaporizer to said condenser. 1

3. A temperature control device comprising a closed chamber constituting a condenser, a vaporizer, a vaporizable fluid within said condenser, a conduit between said condenser and said vaporizer having a relatively poor heat conductivity and-arranged so as to prevent armaterial transfer of heat between said vaporizer and-said condenser. by convection in the fluid in -said conduit and means for heating said vaporizer.

4. A temperature control device comprising. a chamber for receiving a charge whose temperature is to be controlled, a closed chamber surrounding a material portion of said first chamber, a vaporizer remotely situated with respect to said chamber, a conduit between said vaporizer and said second chamber connecting said vaporizer and chamber into a closed system, a selected vaporizable fluid in said closed system and means for heating saidvaporizcr to a temperature sufflciently high to vaporize-substantially allofthe fluid in said vaporizerthatexists in the liquid phase, said conduit having a cross-sectional area sufliciently small to inhibit convection currents in the vaporized fluid in said conduit.

5. In combinatioma closed chamber constituting a condenser, a vaporizer, a tubular member connecting said condenserand vaporizer intov a closed system arranged so that any liquid in said system will gravitate to said vaporizer, a flxed weight of a vaporizable fluid in said system and means for applying heat to said vaporizer so as to vaporize any of said fluid .that exists in the liquid phase, said tubular member being arranged to substantially inhibitthe conduction of heat between said vaporizer and said condenser and having a cross-sectional area sufliciently small to inhibit the transfer'of heat by convection be tween said vaporizer and said condenser.

6. A temperature control device comprising a closed condenser chamber, a vaporizable fluid in said chamber, a vaporizer, a conduit connecting said vaporizer with said chamber arranged to prevent the transfer of heat by conduction and convection between said vaporizer and said chamber, means for applying heat to said vaporizer so as to vaporize substantially all of the free liquid in said vaporizer, and means for controlling the density of the vapor in said condenser chamber.

7. A temperature control device comprising a closed condenser chamber, a vaporizer, a conduit connecting said vaporizer with said chamber arranged to prevent the transfer of heat by conduction and convection between said vaporizer and said chamber, means for applying heat to said vaporizer so as to vaporize substantially all of the free liquid in said vaporizer and means for changing the volume of said condensing chamber.

8. A temperature control device comprising a closed chamber constituting a condenser, a vaporizer in fluid communication with said condenser, a vaporizable fluid within said condenser and vaporizer, means for applying heat to said vaporizer to vaporize substantially all of the fluid in said vaporizer that exists in the liquid phase, means for inhibiting the transfer of heat by conduction and convection from said vaporizer to said condenser so that the temperature in said condenser is held at a substantially constant selected value and a collapsible wall portion in said condenser arranged to be expanded and contracted so as to vary the effective volume of said condenser andthereby'the temperature set-' ting of said device. I 9. A temperature control device comprising a" condenser and a vaporizer connected in a closed system, an'anged so that fluid existing in they 5 liquid phase in said system gravitates to said vaporizer, a selected vaporizable fluid in said closed system, means for applying heat'to said vaporizer so as to vaporize substantially all of the fluid in said vaporizer that. exists in' the liquidity phase, means substantially inhibiting. the trans fer of heat by conduction and convection from said vaporizer to said condenser and means for varying the weight of effective fluid in the vapor phase of saidclosed system. 15 10. A temperature control .device comprising a condenser chamber, a vaporizable fluid in said chamber, a vaporizer, a tubular memberjconnecting said condenser and vaporizer into a closed fluid system arranged so that the fluid in 7 said system existing in the liquid phase gravitates to said vaporizer, said tubular member having a very poor heat conductivity and being arranged so as to inhibit convection currents in the vapor existing in said tubular member, means V for heating said vaporizer sufliciently 'to yahporize substantially all of the 'fluidin said vaporizer that exists in the liquid phase and liquid collecting means for interceptingpre-- selected quantities of the fluid that condenses in said condenser and gravitates to saidvaporizer in the liquid phase so as to vary the weight of effective fluid in the vapor phase in said closed system. V

11. A temperature control devicecomprising a condenser and a vaporizer connected in a closed fluid system, a selected vaporizable fluid insaid closedsystem, means 7 for applying. heat, to] said vaporizer to vaporize the fluid therein existing in the liquid phase, a fluid envelope for said con:

denser, and vmeans controlling the. temperature of said envelope. a d

12. A temperature control device comprising a condenser and a vaporizer connected in a closed fluid system, a selected vaporizable fluid in said (3 closed system means for applying heat to said vaporizer to vaporize the fluid therein existing in the liquid phase, a second condenser surrounding said flrst condenser connected with a vaporizer in a closed fluid system, a selected vaporizable fluid in said second condenser and means for applying heat to said second vaporizer to vaporize the fluid therein existing in the liquid phase.

13. A temperature control device comprising a condenser and a vaporizer connected in a closed fluid system, a selected vaporizable fluid in said closed system, means for applying heat to said vaporizer to vaporize the fluid therein existing in the liquid phase, and means control-e ling the density of the fluid in said system in accordance with the ambient temperature.

14. A temperature control device comprising a condenser and a vaporizer connected in a closed system arranged so that fluid existing in the liquid phase in said system gravitates to said vaporizer, a selected vaporizable fluid in said closed system, means for applying heat to said vaporizer so as to vaporize substantially all of the fluid in said'vaporizer that exists in the liquid phase and means responsive to the ambient temperature for varying the weight of effective fluid in said closed system so as to control the density of the vapor in said system.

15. A temperature control device comprising a condensing chamber, a vaporizer in fluid communication with said condensing chamber, heating means for applying heat to said vaporizer to vaporize the fluid in said vaporizer that is in the liquid phase, means inhibiting the transfer of heat by conduction and convection from said vaporizer to said condenser, and means responsive to the temperature 01 said heating means controlling said heating means to hold a substantially mean temperature between predetermined maximum and minimum temperatures.

16. A temperature control device comprising a condenser and a vaporizer connected in a closed system arranged so that fluid existing in the liquid phase in said system gravitates to said for applying heat to said vaporizer so as to vaporize substantially all of the fluid in said vaporizer that exists in the liquid phase, a fluid collecting chamber arranged to intercept liquid gravitating to said vaporizer, a second chamber in fluid communication with said collecting chamber and arranegd to be adjusted relative to said collecting chamber so as to vary the quantity or fluid in said collecting chamber, and means for adjusting said second chamber.

1'1. A temperature control device comprising a condenser and a vaporizer connected in a closed system arranged so that fluid existing in the liquid phase in said system gravitates to said vaporizer, means for applying heat to said vaporizer so as to vaporize substantially all of the fluid in said vaporizer that exists in the liquid phase, a liquid collecting chamber arranged to intercept liquid gravitating to said vaporizer, a second chamber in fluid communication with said collectingchamber and arranged to be adjusted relative to said collecting chamber so as to vary the quantity of fluid in said collecting chamber, and means responsive to the ambient temperature controlling the position of said second chamber.

18. A temperature control device comprising a condenser chamber, a vaporizable fluid in said chamber, a vaporizer, a tubular member connecting said condenser and vaporizer into a closed fluid system arranged so that the fluid in said system existing in the liquid phase gravitates to said vaporizer, and walls defining an annular chamber surrounding the upper end of said tube with the axis said chamber substantially coaxial with the axis of said tube and arranged to collect fluidgravitating to said vaporizer, the upper end of said tube constituting an over-flow for said annular chamber and arranged so that s fluid flows into said tube from said chamber substantially along the axis of said tube.

19. The method or controlling the temperature of a charge which comprises heating a predetermined volume and weight of a vaporizable fluid sufllciently to vaporize substantially all of the fluid that exists in liquid phase but without super-heating the vapor, and thereby eiiect an equilibriumtemperaturein said vapor, and bringing said charge into thermal relation with said vapor.

20. The method of controlling the temperature oi a charge which comprises heating" a predetermined weight and volume of a vaporizable fluid to vaporize substantially all of the fluid in said system that exists in the liquid phase, but without super-heating the vapor to thereby eflect an equilibrium temperature, bringing said charge into thermal relation with the vaporized fluid, and varying the density of said vapor so asto vary said equilibrium temperature.

21. The method 01 controlling the temperature of a charge which consists in heating a predetermined weight and volume of a vaporizable fluid to vaporize substantially all 01 the fluid existing in the liquid phase, but without super-heating the vapor, thereby eflecting an equilibrium temperature, bringing said charge into thermal relation with said vapor, and varying the volume of said vapor so as to vary the equilibrium temperature. I

22. The method of controlling the temperature of a charge which consists inheating a predetermined weight and volume of a vaporizable 4 fluid sufficiently to vaporize substantially all oi said fluid existing in the liquid phase, but without super-heating the vapor, thereby eiiecting an equilibrium temperature, bringing said charge into thermal relation with said vapor, and vary- 4:,

ing the eflective weight of said vapor at constant volume so as to vary said equilibrium temperature.

MARCUS E. RENE.

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