US2030942A - Refrigeration apparatus - Google Patents

Description

Feb. 18; 1936.-

T. s. sAFFoRD 2,030,942

REFRIGERATION APPARATUS Filed May 20, 1932 5 Sheets-Sheet 1 iNvEN'roR RUM/4N 5. SAFfo/m Feb. 18, 1936.

T. s, SAI-'FORDv REFRIGERATION APPARATUS Filed May 20, 1952 5 Shee'os-Sheefl 2 T. s. SAFFORD REFRIGERATION APPARATUS Feb. 1 8, 1936.

Filed May 20, 1952 5 Sheets-Sheet E INVENTOR l TR1/MAN S. SA Fra/w Feb. 18, 1936. T. s. sAFFoRD 2,030,942

REFRIGERATION APPARATUS I Filed May 20, 1952 5 Sheets-Sheet 4 9 TLF-fj? 95 95 INVENTOR TRL/MAN' S SAfFoRo Feb. 1s, 1936. T s SAFFORD 2,030,942 f REFRIGERATI ON APPARATU Filed May 20, 1952 5 Sheecs--Sheecl 5 Kati the other leg of the Patented Feb. 18, 1936 UNITED STATES PATENT GFFICE 18 Claims.

This invention rel-ates to a refrigerating apparatus and method and to a method and apparatus for compressing and/ or circulating a fluid. More particularly, the invention relates to an apparatus in which compression and/or circulation of a fluid, e. g., a. refrigerating fluid, is eiected by means of-a moving body of liquid impelled dieciy by vaporization and condensation of a Prior to my invention, various devices have been suggested in which alternate vaporization and condensation were to be utilized to create a reciprocating pressure on the surface of a column of liquid which was to be moved thereby to effect the desired compression or circulation. Thus, for example, in one suggested construction, water was to be boiled or decomposed in one leg of a U-tube to drive the remainder ofthe water into tube, there to compress a refrigerant vapor, but with this suggested construction, it has been found that the water vapor passes over into the refrigerant cycle and the refrigerant dissolves inthe water and is carried over into the vaporizing side of the tube, whereV it is boiled out and collects uncondensed until very soon the entire apparatus is rendered inoperative. No construction has been known which could be operative over any substantial period to compress a vapor, e. g., asA required in a refrigerator cycle, or which could be economically practicable in competition with other methods of compression and refrigeration. y

I have now discovered that it is possible to overcome these difliculties, and acc'ordingly I have provided a simple device which will operate satisfactorily for any length of time and at costs which compare favorably with those of other compressing and refrigerating means.

There are obvious advantages of simplicity and entire freedom from leakage and wear which make this type of compressor system very desirable where the over-balancing defects are eliminated.

It is, therefore, an object of the present invention to provide a compressor of this type in which the gas or vapor which is compressed therein is prevented from collecting in the apparatus. It is also an object of the invention to so design such an apparatus as to eliminate waste of heat and to reduce its operating costs so as favorably to compare with those of other compressing means.- A further object of the invention is to provide a refrigerating apparatus in which the fluid of the compressor is prevented from collecting in the refrigerating side of the apparatus,

and the refrigerant is prevented from collecting in the compressor side of the apparatus.

Another object of the invention is to provide a refrigerating apparatus, especially for domestic refrigerators which will operate without noise 5 or vibration and Without Wear, which will be hermetically sealed to prevent any possibility of leakage and which will operate indefinitely without service diiculties.

A Apparatus designed according to the present 10 invention to achieve these and other objects is shown in the accompanying drawings, in which:

Fig. 1 is a diagrammatic View, partly in vertical section, of a refrigeration apparatus designedv especially for domestic refrigeration; 15 Y Fig. 2 is a diagrammatic view similar to- Fig. 1, but simplified therefrom to show the relation oi liquid levels in the various parts of the apparatus;

Figs. 3 and 4 are diagrammatic views similar to Fig. 2, but showing different stages of the 20 cycle; 4

Fig. 5 is a view, partly in vertical section, of another form of refrigerating apparatus embodying the invention; s

Fig. 6 is a view in vertical section of another 25 formof refrigerating apparatus desirable for use in the apparatus of the present invention;

Fig. '7 is a horizontal section taken on line 'I-l of Fig. 6;

Fig. 8 is a view similar to Fig. 1 of a modified 30 form of the invention; y

Figs. 9 and 10 are detail views of a portion of the apparatus of Fig. 1 showing alternative methods of venting gases from 'the compressor backl to the refrigeration side of the cycle;

Fig. 11 is a view partly in horizontal section, as indicated by line Il-H on Fig. 12, of a two stage interrelated apparatus similar to that shown in Fig. 8; and

Fig. 12 is a vertical section taken on line |2-I2 40 of Fig. 11.

Fig. 13 is a wiring diagram illustrating a method of heat control which may be used as an alternative to that described in connection with other figures.

vReferring rst to Fig. 1, I have shown at the right hand side of this gure a refrigerating apparatus similar to the compression type commonly used. 'I'his consistsof a. compressor chamber 20, a condenser 2|, and an evaporator-refrigerator 50 22, with a connection between the evaporator and the compression chamber controlled lby a check-valve 23, a connection between the condenser and the compression chamber controlled by a check valve 24. and a connection between ts A liquid in the compression chamber 20 serves as a piston alternately to draw in refrigerant vapor at low pressure and to expel it at high pressure. The bottom of the compression chamber 20 is connected to the expansion chamber 30 by a passage 26, and also to tht` condenser 3| by a passage 21. The liquid level is at all times above these connections and the volume of the liquid is such that when the compression chamber con- A tains a full charge of refrigerant vapor at low pressure, as shown, e. g., in Fig. 2, the condenser -3| and the expansion chamber 30 -are full of liquid, asare also the U-tube connection 32 between the top of the expansion chamber and the top of the condenser, the measuring chamber 33 and both of the connections 26 and 21.

A passage 34 connects the top of the expansion chamber 30, the top of the passage 32 and the top of the measuring chamber 33, and also connects these with a boiler chamber 35, which in the present case is heated by a. surface 4combustion heater 36 supplied with a combustible gas mixture by the tube 31. l

This boiler 35 is preferably designed to store up a relatively large amount of heat and to superheat the vapors formed therein. To this end, a

number of baiiles are shown in the drawings, but it is to be understood that any other means may be adopted for this', purpose, e. g., the boiler may be filled with loose bailling material of high heat capacity and heat conductivity, such as turnings or irregularly shaped pieces of aluminum orl copper.

A syphon 39 connects the bottom of the measuring chamber 33 to the bottom of the boiler at a level just below the bottom of connecting pascooling surfaces 42 and external fins or otherextended surfaces 43 serve to transfer the heat rapidly from the vapor into the cooling air and to effect rapid condensation of the vapor.

A stack 45 serves to`carry oif the combustion gases fromthe boiler 35 and the heated air from the condensers 3| and 2 and the draft from this stack serves to maintain a rapid circulation over thecooling surfaces of the condensers. It will be understood also that the gases of the combustiblegas mixture may be preheatedby heat-exchange from any of these three sources. The jackets 46 and 41 serve to direct the air circulation close to the heat-exchange surfaces of the condensers.

As this apparatus just described stands idle, the vapors of the liquid are condensed in 3| so that the liquid level .rises to the top of that chamber,

and therefore fills the U-passage 32, the measuring chamber 33, and the expansion chamber 30,

and is drawn out fromthe compression chamber 20 causing the vapors of the refrigerant, evaporated in 22, to substantially fill said chamber 20.

Upon heating of the boiler 35, the liquid, which has been syphoned over through 39 from the measuring chamber 33, is boiled and the vapors thus formed are superheated and passed over into the `:hamber 30, Where it forces displacement of the liquid therefrom. Since the condenser 3| is already filled, there is only one escape for the disthe condenser and evaporator controlled by the. float valve 25.

placed liquid, that'is, into the compressionchamber 20.

The displacement of the. liquid from the expansion chamber 30 into the compression chamber 20 results in the compression of the refrigerant vapor therein and eventually in their displacement from the compression chamber through the valve 24 into the condenser 2|.

During the displacement of the liquid from the chamber 3|), the level in the connecting tube 3'2 must, obviously, remain the same as that in the chamber 30. The charge of liquid in the measuring chamber 33 is slightly more than enough to `depress the liquid to the level of the bottom of the U-connection 32, e. g., as shown in Fig. 3. At this point the compression chamber is substantially lled with the liquid'and the refrigerant substantially entirely driven out. When this point has been reached, however, no further displacement of the liquid can occur, and there is no danger of the liquid being driven up through the valve 24 into the refrigerating cycle.

The additional vapors produced by the boiling of the last of the liquid from the measuringV chamber 33, instead of displacing more liquid from the chamber 30, escapes through the co'n-v nection 32, and as it bubbles up on' the other side of the U, the liquid seal therein isbroken and an 'inverted vapor-syphon is formed therein.-

Immediately the liquid in the chamber 30 and the condenser 3| tends to seek a common level,

as shown in' Fig. 4; and as condensation occurs in the condenser 3|, the levels in the two remain substantially equal until the liquid has risen thereinsufficiently to spill over into the connection 32 and to restore thereby the liquid seal between 3|! and 3|.

When this stage is reached, the liquid has been drawn out from the compression chamber 20 and has been replaced therein lby a fresh charge of refrigerant vapor at low pressure, and thus is restored to the condition illustrated by Fig. 2.

`At the same time that the liquid spills over into 32,it also fills the measuring chamber 33, but it cannot ll the syphon 39 so asto start the feed to the boiler until the connectionV 32 has been-filled, because the syphon tube 39 `is substantially above the level of the top of the wall between the tube 32 and the measuring chamber 33.

As soon as the tube 32 has been filled so that the level can rise above the syphon 39, the feed to the boiler begins and the superheated vapor at once begins to drive down the level in the chamber 30 and the tube 32. Thus the cycle is repeated indefinitely.

Although the device as just described can be operated with continuous heating of the boiler, and ordinarily would be so operated where a liquid fuelis used,`I have illustrated in Fig. 1 an apparatus adapted for intermittent operation, e. g., with gaseous fuel. Where continuous heating is used, the boiler is merely storing up heat by raising the temperature of its walls and bailies, etc., and this heat is subsequently used for boiling. the liquid and superheating the resulting vapors. Where an easily controlled source of heat is used, it is ordinarily more economical to use intermittent heating andv for this purpose a thermostat is provided controllingA the valve 4| in the gas line 31 (or in the steam `line ora switch in an electrical heating circuit, or other heat control means).

When the liquid seal is broken at the end of the first step" of the cycle (as shown at Fig. 3),

frigerant which are chosen.

vagrancy of the materials and to conne them,

- ticular liquid chosen the materials chosen for very hot vapors pass over through the connection 32 and impinge upon the thermostat 40. The sudden rise in temperature from that of the liquid which has been cooling in the condenser during the preceding step to that of the vapors heated to the boiling point of the liquid at the highest operating pressure causes the operation of the thermostat 40 to shut off the heating of the boiler 35. When, at the end of the condensing step, these hot vapors are again converted into liquid at the lowest operating pressure, the temperature is such as to cause the thermostat 43 again to turn on the heat for the boiler 35.

In the preferred embodiment, the heating means 36 is a. surface combustion gas heater. It may, however, be any other desired means for supplying heat, as for example merely a jacket for circulation of a hot fluid, or an electric resistance heater. The surface combustion heater has proven most advantageous, both because of its superior heat exchange possibilities and its more complete combustion, and because of the ease with which an ignition catalyst, e. g., palladium black, may be supported thereon so that intermittent heating with gas may be carried on without the use of a pilot light or spark ignition means.

It is desirable for the sake of economy to avoid heat losses so far as possible, except where condensation is eifected. Thus I have encased in insulation 49 the boiler 35 with its heater 36, the chambers 33 and 30, the connections 34, 26 and 32, and the'bottom of the condenser 3|. It is to be understood, however, that such insulation may be extended farther or omitted partially or entirely.

In the operation of this apparatus, there is likely to be more or less refrigerant dissolved in the boiling or piston liquid and more or less Vapor of the liquid mixed with the refrigerant vapor, depending upon the liquid and the re- To control this each to its own part of the apparatus, I have found it desirable to use a liquid which oats upon the boiling liquid, which has very low vapor pressures at the temperatures to which it is subjected, and which does not appreciably dissolve the refrigerant vapor under the conditions met with in the compression chamber 20. 'I'he parwill depend, of course, upon boiling liquid and for refrigerant. Usingcarbon tetrachloride as the boiling liquid and methyl chloride as the refrigerant, I have found that glycerine masI serve as the sealing liquid between.

It is sometimes preferable not to use such a sealing liquid, or it may not be possible to find a liquid which is inert, insoluble and of low lvapor pressure as required for a given refrigerant and boiling liquid which it may be desired to use. In such case-and, in fact, even where such a sealing liquid is used-it is advantageous to provide some means of returning the accumulations of fugitive materials. Various devices for this purpose are shown in Figs. to 10.

Considering rst the fugitive refrigerant which may be dissolved in the boiling liquid and boiled out in the boiler 35, eventually collecting in the condenser 3|, I have shown in Fig. 8 a preferred device for returning such refrigerant vapors.

In Fig. 8 the expansion chamber 30, the connections 32 and 34, the syphon 39, the measuring chamber 33 and the boiler 35 with its heater 36 may all be the same as in Fig. 1. The compression chamber 20 is substantially the same except that in this case it is higher than the chamber 30. The two are connected as before by the conduit 26. In this case, however, the condenser chamber 3| is smaller and at a higher level and it is connected to the lower part of the compression chamber 20 by a conduit 3| a which is preferably level and provided with sufficient cooling surface to fully condense all vapors of the boiling liquid before they reach the chamber 20; this may be tortuous instead of straight.

In the operation of this embodiment of the lnvention, the first or compression step proceeds as has already been described in connection with Fig. 1. In this case, however, once the liquid seal is broken in the connection 32, the apparatus becomes merely a closed cycle system with vapors at a level below liquid, which naturally seek to rise to the top of the liquid. The vapors therefore pass up into 3| and through 3|a and any which, during this travel, have escaped condensation may thus bubble through the liquid in chamber 20. The c'ondensers 3| and 3|a are arranged and designed so that the only vapors which will remain as such at the surface of the liquid in chamber 20 will be the refrigerant va-A pors. All vapors of the boiling liquid will be condensed before that point is reached.

Figs. 9 and 10 show alternative methods of venting refrigerant vapors. Fig. 9 shows an apparatus which may be substantially identical with that shown in Fig. l, except for the thermostat 3|b and the connection 3| a, and that the compression chamber 20 is above the level of the condenser 3|. In this case, the hot gases which come over through the connection 32 at the end of the compression step of the cycle close the thermostatic valve 3|b, and this valve remains closedV until condensation has progressed sufficiently to avoid any danger of the vapors of the boiling liquid escaping uncondensed into the refrigerant space. When this point has been reached, the valve is opened and the vapors of course pass over through the connection 3|a, either with or without further cooling and condensation therein.

The device shown in Fig. 10, although shown at the same levels as in Fig. 9, is substantially independent of the relative levels, because of the use of two additional valves 3| c and 3Id. Near the end of the compression step, the pressure in the entire apparatus is high and any uncondensed gases remaining in the condenser 3| are forced through the valve 3|c into the connecting passage 3la. At a subsequent stage in the cycle, when the pressure in the chamber 20 is low, the gases thus compressed in 3|a. expand through the check valve 3|d and bubble up through the liquid in the chamber 20 to rejoin the refrigerant vapors.

In Figs. 5 to 7, I have illustrated by way of example how any fugitive liquid may be returned from the refrigerating side of the cycle to the compressor. As shown in Fig. 5, the cooling unit 22 is advantageously positioned above the level of the compression chamber 20 and as shown in Fig. 1, the condenser 2| is advantageously above the level of the cooling unit 22. Thus the compressed vapors from the compressor chamber 20 rise first to the top of the condenser 2|, from a series of bafile plates with staggered openings between, and each designed to maintain a shall low pool of liquid thereon, so that heat transmitted through the metal from the side wall will effect evaporation of the liquid.

In Figs. 6 and '7 is shown another and somewhat more desirable form of bailled cooling unit. In this case, the baffles are designed to avoid pockets, and when this is used, there need be absolutely no place for the fugitive boiling liquid to collect. The liquid coming from the condenser 2| ows into the top of this unit onto the first of the bafiies 55, and thence down over successive baiiles to the outlet 56l and back to the compressor chamber 20. Each of the baiiles is tilted slightly so that the liquid will ow slowly thereacross and is made with staggered ridges 51 which require 'the liquid to follow a tortuous path over the baille. Thus the liquid is extended over the surface of the baflies and rapid evaporation and heat transfer' effected.

In Fig. 5 I have shown also an alternative compressor unit. In this case the compressor chamber 2U and the expansionl chamber 30 and the connection 26 are shown of different shape, but their functions are the same. In this case, howeverAthe condensation of the vapors during the intake step is effected entirely in the condenser connection 3Ia, and the boiling is eifected in the expansion chamber by Aan electrical resistance heater 36a. and no separate boiling chamber, measuring chamber or condenser chamber is provided.

The connection 3Ia is controlled as in Fig.' 10 by check valves at each end. In this case, however, the valve 3|c is a specially designed piston valve, while the valve 3|d is designed to operate with a very slight pressure difference caused by a relatively small difference of level between the liquid in chamber 20 and that in chamber 30. This valve 31d may be omitted entirely, but its use permits the condenser 3la to be of smaller capacity, since condensation may go on during a following compression step and a low pressure may result in the condenser which will cause more rapid clearing of thevapors from the expansion chamber.

The valve 3 Ic is made with a cam face 60 on its upper metallic surface and an annular cam groove 6I lined with an insulating material such as a porcelain enamel or a phenol formaldehyde resin, etc. 'Ihe upper conical cam surface. 60 is so designed that when acted upon by the spring pressed brushes`63, it will be held against its seat until subjected to a pressure greater than that at which the refrigerant is forced out through the valve 24. The -spring 64 and the insulating cam surfaces 6| and the brush springs 66 are so designed and related that the valve will be held opened until the pressure is reduce'd sufiiciently to assure that the vapor is all or largely expelled from the expansion chamber 30.

The heater 36a is supported on a core 68 secured to or integral with the head of the chamber 30, and the circuit of the heater is connected through the brushes 63 and the contact portion 60 of the valve 3Ic. Thus when the valve 3Ic is opened, the heating circuit is broken; and when the valve is closed, the heating circuit is reestablished.

In the construction shown, the heating circuit is connected to the right hand brush 63 and, through a connection not shown to the right hand conducting link 69. The cover 10, with its insulating sleeves 1I, spring 66, brushes 63, conducting sleeves 12, and conducting links 69, may be first assembled. The intermediate part 68 may then be assembled with the heater 36a and the valve 3|e and the rivet or screw connections of the links 69 may be secure'd through the part 68 to the resistance element of the heater 36a. All may then be assembled. The part 68 may be of insulating material such as bakelite, etc., or it maybe, as shown, of metal with insulating washers around the connections from the links 69 to the heater 36a.

A float 15 and a back valve 16 are provided on the stem of valve 24 for the purpose hereinafter explained.

In the operation of the device shown in Fig. 5, the liquid, which should ll the apparatus above the level of the valve 3Id is rst boiled by the electrical heater 36a. until the refrigerant vapor has been substantially entirely expelled through the valve 24. At this time, the liquid level nears the top of the chamber 20 and begins tov submerge the float 15. 'Upon further boiling of the liquid in 30, the liquid raises this float and presently closes the valve 16, whereupon, no further escape being possible, the pressure rises rapidly -within the apparatus until it is sufficient to open the valve 3Ic. When this occurs, the insulating band 6| is interposed between the brushes 63 and the heating circuit is broken.

The vapors now pass out from the chamber 30 by the valve 3Ic into the condenser 3Ia until the condensation has so reduced the pressure in `the chamber 30 as to allow the valve 3Ic to be float 15 to drop once more to the position shown.'

This same system of valves and compressor may 'also be used with other types of heat and whether the boiling is effected within the expansion chamber or in 'a separate boilingchamber, as in Fig. 1. In the latter case, the charge measured by chamber 33 should be enough to assure the building up of excess pressure after the refrigerant charge is discharged from the compression chamber 20. In either case, the heat may be controlled directly by the valve 3Ic or by a separate pressure responsive control, or by a circuit through 63 and 60, etc., and which may be used -to control the heating by operation of valves, etc.

In Figs. 11 and 12, I have illustrated a twostage compressor. An arrangement of this kind makes possible considerably greater economy than is possible with the single compressor. In this case, the initial'compressi-on is effected in the l When the compression step is completed on the right hand side, the vapors pass over from the expansion chamber 3BR into the vapor dome 3 IR. and a special condenser-boiler heat-exchange unit and thence back to the compression chamber 20B. In the heat-exchange unit 80, the vapor of the liquid used in the right-hand side is condensed and gives up its latent and sensible heat to the liquid used on the left-hand side. In the preferred form of the invention, the liquid used on the right-hand side boils at a much higher temperature than that used on the left, so that even at the lower pressure existing in 2DR, as compared with 20L, the liquid used on the lefthand side will be boiled by heat transferred from the condensing vapors from the left-hand side. Thus, for example, I may use on the left-hand side a substance such as butane or iso-butane, which boils at relatively low temperatures at the highest pressures encountered, and for the liquid used in the right-hand unit a substance which boils at relatively high temperature even at the lowest pressure encountered. 'I'he latent heat of vaporization and the specic heat in the boiling range should, of course, be low if maximum economy is to be attained. Carbon-tetrachloride, trichlorethylene, hexane, heptane, and ethyl alcohol are examples of liquids suitable for the right-hand side and butane, iso-butane are examples of materialssuitable for the left-hand side. The liquid used on the left side should preferably be one which at about F. has a vapor pressure approximately the same as that at which the refrigerant is discharged from the first stage compressor 20L, and this pressure is preferably chosen so that the heat of condensation from the first stage will be alittle more than enough to boil the entire charge in the second stage.

The Waste gases 4from the boiler 3BR pass through the heat-exchanger 8| where, during the compression step on the left side, they serve to superheat the vapors generated in 80. During the remainder of the cycle, said gases store up heat in this heat-exchanger ready for the next compression step. From this heat-exchanger, the waste gases go to the flue 45.

When the operation of this two-stage device begins, the liquid in the condenser and expansion chamber is cool, and therefore at a very low vapor pressure; the compression chamber 2DR, therefore, i's full of refrigerant vapor. As the liquid is boiled in the boiler 3ER, the liquid level is driven down in the expansion chamber 3BR. and up in the compression chamber ZUR.

The refrigerant in 20B, is rst compressed and then expelled through the connection 82 and into the compression chamber 20L, ywhere it drives down the liquid level, increases the pressure on the vapors in the condenser 3|L and causes condensation of the vapors in the condenser until the measuring chamber 33L is lled and the syphon 39L begins to feed into the boiler-condenser 80.

In the meantime, the vapor from the expansion chamber 3DR, has broken the liquid seal in 32R and passed over into the vapor dome 3IR andthe boiler-condenser 80. In the latter, the vapor from 3DR. gives upits heat to the'liquid from 30L and is condensed while the latter is boiled.

The vapors boiledin80 and superheated in 8l return to the expansion' chamber 30L, where they drive. the liquid out into-thecompression chamber 20L and thereby drives the. compressed refrigerant vapor out into the condenser 2l (not shown in this figure). This continues until the liquid seal is broken in 32L and the vapors pass over into the condenser 3IL, and in the meantime the condensation of vapors in the boiler-condenser 80 has served to draw the liquid from the compression chamber 20R into the expansion chamber 30R and nally into the measuring chamber 3BR.

This cycle is repeated with alternate compression, first in 20B. and then in 20L and with the condensing vapors from 30R supplying the heat for the compression step in 30L.

With the operation of this apparatus as just described, it is advantageous to use a piston liquid oating on the boiling liquid in chambers 2BR and 20L to seal the boiling liquid and prevent evaporation of the latter into the refrigerant space. Furthermore, .it .is ordinarily desirable to use the same piston liquid in both of the chambers ZUR and 20L, so that such slight evaporation as may occur from the surface of this liquid may be returned in the cycle. Thus, vapors from the surface of the liquid in 20L will be condensed in the refrigerant side of the apparatus and eventually returned to 20R.` If an excess of the liquid should thus be distilled over into 20R, it would merely pass over through 82 as a liquid and be restored to 20L. That, however, will not often occur, since as a practical matter, the evaporation comes largely from the surface of the liquid in ZUR and the vapor thus mixed with the refrigerant serves to prevent evaporation in 20L.

If it is desired to avoid the use of a piston liquid, or for any other reason to use the same boiling liquid on both sides of the apparatus, the operation must be the reverse of that just described. That is, the. initial compression will take place in 20L and the second stage in 2DR. Since the higher pressure is in the right-hand part of the eapparatus, the same refrigerant may be used and its boiling point at the higher pressure prevailing on the right-hand side will be enough higher than its boiling point in the lefthand side to permit the operatic-n of the boilercondenser 80, as already described.

For automatic operation of any of the apparatuses embodying my invention, the heating supply will ordinarily be controlled by a thermostat in the cooled space. If the apparatus is properly designed, its operation may be intermittent and the heating source may be turned on and'oif as the temperature varies above and below a prescribed temperature level. I nd it more satisfactory, however, to design the apparatus for continuous operation and to regulate the heat source instead of cutting it olf completely. The apparatusfurthermore, lends itself perfectly to the various other controls which may be desired, such for example, as cold control, defrosting control, etc.

Although the design of the various parts may be altered and varied to meet the exigencies of any particular situation or the fancy of a designer, nevertheless, in many respects the designs shown have been'chosen advisedly. Thus, I have found the use of a converging top in the compression chamber 20 permits greater efliciency because it allows almost complete expulsion'bf the refrigerant vapor without driving out the liquid. The

side of the U-connection 32 which opens into the condenser 3l should be made small enough -so that it may be substantially cleared of liquid by the bubbling of vapors therethrough and the air I sure used in the apparatus.

cooling, but no great amount of condensation. The condenser 2l is preferably made as shown with a riser direct to its top and a gravity flow from` there back to the compressor chamber, through the condenser coils, the float or expansion valveor orifice, and the cooling unit.

I have suggested above certain materials which may be used as boiling liquids; it is to be understood that these are cited merely as examples of numerous liquids which may be used. 'Ihe choice of a liquid in any particular case is determined by certain recognized properties and when it is understood what properties are necessary, this choice will involve little diiiculty.

Primarily, of course, the boiling liquid must be one which boils at a reasonable temperature under the highest pressure used in the apparatus, and which condenses above, but preferably not far above, the highest atmospheric temperatures which are likely to occur when at the lowest pres- Of course, if cooling Water is used, the liquid may be allowed to condense at a lower temperature. Secondly, the

liquid should, for'the sake of economy be one which in the temperature range Aused should have low latent and specific heats. Thirdly the liquid must be inert as to the parts ofthe apparatus with which it comes in contact and as to the refrigerant, and preferably -the liquid should not dissolve the refrigerant; although if a thoroughly f efficient piston liquid is used to seal the boiling liquid from the refrigerant, a liquid may sometimes be chosen which is not entirely inert in this respect, or which does dissolve the refrigerant to some extent. Preferably the liquid should be non-inflammable, non-poisonous, possessed of an odor strong enough to give warning if a leak should ever occur andavailable on the market at relatively low price.

When sulphur dioxide is used as refrigerant, I prefer to use pentane or iso-pentane as the boiling liquid. No liquid has as yet been found which combines all of the desirable properties enumerated. A

When a piston liquid is used, it will be chosen primarily for its low vapor pressure. Secondly, it must be .inert with respect to the apparatus materials, the piston liquid and the refrigerant, and preferably should not dissolve any of them.

. Its specific gravity must be substantially different from that, of the boiling liquid; and unless the apparatus is redesigned to use a heavier piston liquid, this liquid should be enough` lighter than the boiling liquid always to iloat thereon. If a heavier liquid is preferred in any case, a well should be provided below the connection from the condenser 3l to the expansion chamber 30 and the bottom 'of this well may be connected to the compression chambeir 20 so that only the piston liquid can pass into the latter.

When methyl chloride is used as the refrigerant and carbon tetrachloride or pentane as the boiling liquid, I have found glyoerine as the most satisfactory piston liquid.

Numerous variations of the above are possible y utilizing the principle of my invention. Thus it may be used in an absorption cycle; e. g. the compressor acting as the strong liquor circulating pump and the heat from the compressor condenser or from the boiler stack gases or both being used in the generation of the convention absorption cycle.

. When used in the' absorption cycle the strong liquor itself may serve as the boiling liquid, am-

2,oso,c4a

lcooling of this tube is preferably designed to effect monia being boiled out from the liquor in the expansion chamber and vented, e. g., through a l, counter current heat-exchanger in the generatoi`l and/or strong liquor intake line, back to the compression chamber. In this case I prefer te use a boiler arrangement such as that showr in Fig. 5, i. e., with the heating means within the l expansion chamber. The ammonia gas released in the expansion chamber maybe released at the end of the stroke either through a liquid-seal inverted syphon as in Figs. 1 to 4 and 8 to 12 or by means of a valve mechanically or electrically operated.

It is an advantage of the presentinvention that it is capable of infinite variations to meet the exigencies of varying situations. Numerous other forms of the apparatus may be used and numerous other controls; thus, by way of example, when mercury is used as a piston liquid it may make and break a circuit through contacts positioned in one of the chambers and may thereby control the heating or cooling, the operation of valves, or any other part of the apparatus. I have illustrated this by a wiring diagram in Fig. 13. i

In this figure electric current from any source flows in through the main leads and 9|. Upper contacts 92 are in seri'es in this circuit and positioned within one of the chambers just below the upper mercury level. The circuit of a relay 93 is, when open, controlled by these contacts 92 but is adapted when once operated'to shunt out the contacts 92 through the contacts 94 and thus to remain closed even after the circuit through the contacts 92 is broken by lowering of the mercury level. This relay 93 may also control the heating circuit, etc., through the contacts 95.

A second pair of contacts 96 are also in the circuit of the relay 93 and may be positioned just above the lowest level of the mercury so that when the mercury falls below, this level the relay circuit is broken and its armature will be dropped. Thus the heating will continue from the high mercury level to the low and will be shut oi thereafter until the high is reached again.

A similar system may be used where the piston or boiling liquid is a dielectric by positioning spaced plates of a condenser instead of contacts within one of the chambers. the capacity of the condenser with change of dielectric` may be utilized to operate a relay or other control device.

Valves, -heating or cooling means, etc. may also be controlled'directly by the liquid level, e. g. by means of floats, or by float operated switches. Thus in one case I have used two floats connected by a thin shaft. A lower float at about the low level of the liquid is designed to balance by its buoyancy the weight of the upper float in the vapor, the upper oat is of sufficient buoyancy when it is submerged to operate a mercury switch; and the weight of both floats andthe connecting shaft is suilcient to operate said switch the other way when the liquid level drops below the lower oat.

The variation in Referring again toFig. 10, the condenser conl MN... r

ber andthe connection may be from the top of the expansion chamber, as in Fig. or from the top of the condenser chamber, as in Fig. 10, and may connect with any other part of the apparatus, e. g. lower in the chamber 20 or in the connection 26 or lower in the same chamber, although in this latter case there will not be venting of fixed gases, as in Fig. 10, but only condensation of vapors.

Although it is best to operate this type of pump by vaporization and condensation in the strict sense without decomposition of any kind, nevertheless it is possible to utilize any reversible change from liquid to gaseous state whether it is a purely physical change or involves chemical reaction or decomposition.

The terms vaporization and condensation as used in the accompanying Iclaims are therefore to be broadly construed to include chemical reactions, as, for example, is the case with release of ammonia from ammonium hydroxide solution.

I have chosen the phrase oating piston to describe a piston which is driven by fiuid pressure variations as distinguished from pistons driven by mechanical means.

Although in the above I have suggested a preferred form of my invention and various modifications thereof, it is to be understood that these are merely exemplary of the invention and that it may be embodied in numerous other ways.

What is claimed is:-

1. A refrigerator comprising a compressor which includes a U-shaped housing forming a compression chamber, an expansion chamber, a measuring chamber, a vaporizer, and superheater, a vaporizable liquid piston, a syphon adapted to feed liquid from the measuring chamber to the vaporizer, a surface combustion heater for said vaporizer and superheater, a condenser at a level not lower than the expansion chamber connected to a part of said housing which is normally below the liquid level therein, a U-tube connecting the top of the expansion chamber to the top of the condenser with the bottom of the U at a level approximately that of the liquid therein at the end of the compression stroke, a

`vent from the top of the condenser to the compression chamber, a thermostat near the top of the condenser for controlling the supply of fuel to said heater, and a sealing liquid separating the vaporizable liquid from the refrigerant in the compression chamber; a refrigerant compressor and an evaporator designed and related so as to provide a continuously descending path for liquid from the highest point of the condenser through the evaporator and back to the compressor; a stack into which the products of combustion from the heater pass, an air jacket around the condenser of said compressor and opening into the lower part of said stack, and an air jacket around said refrigerant condenser andl opening into a lower,part of said stack whereby waste heat from said compressor will create a draft to draw cooling air over said refrigerant condenser.

2. A pump comprising two confined columns of liquid connected below their lowest normal levels, the liquid at the topof one column being capable of repeated vaporization and condensa.- tion at the temperatures and pressures normally occurring therein, and the liquid at the top of the other column being one which has a low vapor pressure at the temperatures normally there occurring and in which the substance to be compressed thereby is relatively insoluble, means confining said columns and the connecting body of liquid, the volume of said confining means being greater than the volume of the liquid, means for vaporizing liquid over the first column, means for condensing resulting vapors in a separate space communicable with the vapor space over said first column and with a part of said confining means into which condensate may be drained to return to said first column, means adapted to control the communication between said condensing means and said vapor space to permit escape of vapors therethrough only after the end of a compression stroke, and said confining means having valves over the second named column, one adapted to permit the entry of fluid therethrough when the pressure in said space is reduced and the other adapted to permit expulsion of iiuid therefrom when the pressure is raised.

3. A pump comprising two confined columns of liquid connected below their lowest normal levels, the liquid at the top of one column being adapted readily and repeatedly to release a gas which can again become a part of the liquid, and the liquid at the top of the other column being one which is adapted to drive the material to be pumped, means for confining said columns and the connecting body of liquid, means for releasing a gas'from said liquid within the confined space of said first-named column, means for restoring said gas to said liquid in a separate space communicable with the first, means adapted to control the communication therebetween so as to permit escape of gas from the first column to said space only after the end of a compression stroke, and said confining means having valves over the second named column, one adapted to permit the entry of fluid therethrough when the pressure in said space is reduced and the other adapted to permit discharge of fluid from said space when the pressure is raised.

4. A liquid piston pump comprising a housing including a compression chamber, an expansion chamber and a connection therebetween below their lowest normal liquid level, a vaporizable liquid therein, means for vaporizing said liquid communicable with the expansion chamber and a U-passage connecting the upper part of the expansion chamber to another part of said housing, the lower passage of said U being at substantially the same level as that of the liquid within the expansion chamber at the end of a compression stroke, whereby said U-passage will form a liquid seal for said vapor space until the end of said stroke whereupon the seal will be broken and the vapor allowed to escape.

5. A pump comprising a U tube, a vaporizable liquid therein, a measuring chamber arranged to be filled by overflow from the top of one side of said U, a boiler connected to said U tube and adapted to be fed by said measuring chamber after the level of liquid in that side of the U is below the measuring chamber, and an inverted syphon from the top of the same side of the U as said boiler and measuring chamber adapted normally to be closed by a liquid seal, but to syphon vapors from said top of one side of the U tube to another part thereof when the liquid level on that side has been forced below a given point in said tube. i

6. A pump as dened in claim 5 which further includes a connection to other side of U whereby 7. A pump as defined in claim which further includes an inverted syphon connected to condenser whereby to condense the vapors before they are returned to the U-tube.

8. A pump comprising a liquid piston, means for vaporizing a liquid over said piston whereby to drive it into a compression chamber, means for cooling said vapor to condense it and thereby to draw the piston back from the compression chamber, and means for venting gases from the vapor space into said compression chamber.

9. A liquid -piston pump comprising a housing including a compression chamber, an expansion chamber and a connection therebetween below the lowestl normal liquid level therein, a Vaporizable liquid therein, means for driving and retracting said liquid piston by vaporization and condensation, and a body of sealing liquid in said compression chamber separating the veporizable liquid from the material being pumped, said sealing liquid being substantially immiscible with the vaporizable liquid, and the material being pumped and having a relatively low' vapor pressure at the operating conditions.

1 10. A pump comprising a series of expansion chambers and a corresponding series of compression chambers, a connection between each expansion chamber and' a compression chamber beylow the normal liquid levels therein, heating means associated with the first one of said expansion chambers for vaporizing a liquid to drive down the liquid level therein, a heat exchange means connected to each expansion'chamber of the series except the first adapted to effect vaporization of a liquid to Ydrive down the liquid level if said expansion chamber and each of said heat-exchange means being connected to the expansion chamber next preceding in the series by a connection which is adapted to be open only at the end of a compression stroke whereby the vapors exhausted from one expansion chamber are condensed and the liquid of the next expansion chamber is vaporized by heat-transfer from the vapor to the liquid in said heat-exchanger, and a condenser assoclatedwith the last of said series of expansion chambers to condense the vapor utilized therein.

11. A multiple stage pump 'as defined in claim 10 in which the outlet of each compression chamber of the series except one is connected to the inlet of another compression chamber of the series, whereby the pressure of a fluid may be stepped up successively in the several compression chambers of the series. i

12. A pump comprising a housing including a vaporizer, an expansion chamber, and a compression chamber, a floating piston therein,

means for heating the vaporizer, means for turning .on said heating means when the piston reaches a position near one end of its travel and for turning it on when the piston reaches a position .near the other end of its travel.

13. A pump as dened in claim 12 which further comprises a condenser communicable with the expansion chamber, means for controlling the communication therebetween to permit escape of vapors to the condenser only at the end of a compression stroke, a thermostat in said condenser adapted to cut off the heating means when hot vapors enter the condenser and to tw'n o1- said heating means when s aid vapors are all cooled to a temperature at which they are cindensed.

14. A refrigerator apparatus which compris .s a compressor as defined in claim 3,A a condenser and an evaporation chamber, the condenser and evaporation chamber being substantially above the level of said compressorand the path of refrigerant fluid through said condenser and evaporation chamber to the compressor being substantially consistently downward whereby compressor liquid carried over into said refrigerating part of the apparatus will flow back into the compressor. g

15. A refrigerating apparatus comprising a compressor having a liquid piston, a refrigerant condenser and an evaporator all in closed cycle, said condenser and evaporator being above. the level of said liquid piston and being so related and designed as to provide with intermediate connections a continuously descending path from the highest point thereof back to the liquid piston in said compressor adapted to return to said liquid piston any of its material which may be carried over into the condenser. i

16. The method of artificial refrigeration which comprises confining a refrigerant vapor over a' liquid piston, alternately expelling said Vapor from the confined space under 'higher pressurev and drawing vapor back at lower pressure, condensing the refrigerant at a level above the piston, refluxing condensed refrigerant and any entrained piston liquid back to the confined space by a continuously descending path including a refrigerating evaporator.

`17 The m'ethod of pumping fluids which compises confining the fluid over a oating piston, reciprocating said piston by alternate'vaporizationand condensation of a uid on the opposite side thereof and venting from the vaporization side to the compression side of said piston fugitive gases which have escapedtc the vaporization side by solution in the vaporizing liquid.

18. 'I'he combination of a refrigerating device operated by heat exchange at a portion of said device at relatively high temperature with hot gases, and heat exchange at another portion thereof at relatively low temperature to the atmosphere, a stack, means connected to said stack surrounding said high temperature heat exchange portions to direct the hot gases passing therefrom into the stack, and means independently connected to the stack surrounding said low temperature heat exchange portion, adapted to utilize the draft created in the stack by said hot gases to draw air at existing atmospheric. temperature over said cool heat exchange portion, and adapted substantially to prevent said low temperature portion fromexposure to heat from the high temperature portion.

TRUMAN S. SAFFORD.

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