US2151948A - Apparatus for effecting refrigeration - Google Patents

Description

March 28, 1939. E. TURNER APPARATUS FOR EFFEGTIYNG REFRIGERATION 3 Sheets-Sheet 1 Filed April 26, 1934 llI-I|llilhnlllnlllllinllllllll\ //V VIE/V701? EDWARD 7. TURNER March 28, 1939. E. T. TURNER 2,151,948

March 28, 1939'. E. T. TURNER APPARATUS FOR EFFEGTING REFRIGERATION Filed April 26, 1954 v 3 Sheets-Sheet 3 //vv/v 7'0/2 Jam/R0 7. TURNER.

his 4 TTOH/VE Y Patented Mar. 28, 1939 UNITED. STATES" mma'rns roa EFFEOTING REFRIGER- ATION Edward T. Turner, Dayton, Ohio Application April 26. 1934, Serial No. 722,446

4 Claims.

This invention relates to an apparatus for effecting refrigeration, Y

A further object of the invention is to provide an apparatus which will be simple in construction and operation and which can be installed and operated at a low cost.

A further object of the invention is to provide an apparatus which will not require the use of an expansion valve in the line leading to the evaporator or a float valve in the evaporator.

A further object of the invention is to provide an apparatus of such a character that leakage of air into the system and the escape of refrigerant therefrom will be efiectively prevented.

Afurther object of the invention is to provide a centrifugal pump which will have a high' degree of eiiiciency when constructed in small sizes.

Other objects of the invention will appear as the apparatus is described in detail.

In the accompanying drawings Fig. 1 is an elevation, partly in section, of one form of apparatus embodying my invention; Fig. 2 is an elevation, partly insection, of a slightly modified form of the apparatus; Fig. 3 is alongrtudinai sectional view taken through the pump, and partly broken away; Fig. 4 is a transverse sectional view taken through the pump and the injector on the line 4-4 of Fig. 3, and partly broken away; Fig. 5 is an elevation, partly in section, of another modified form ofthe invention; and Fig. 6 is a sectional view of the pump showing a modified form of discharge nozzle.

' In these drawings I have illustrated one form of apparatus, together with certain modifications thereof. In that form shown in Fig. 1, vaporized refrigerant is taken from the evaporator Ill and delivered through a pipe II to an injectorl2 which forms part of a conduit leading from a pump l8 and is connected by a pipe M with a separator IS. A liquid. propellant is discharged from the pump through the injector at high velocity and the injector is of such a character that the vapor which has entered the same will be compressed in the liquid and delivered therewith to the separator l5, where the liquid is separated from the vapor and returned through a conduit I6 to the pump. The vapor escapes from the upper portion oi. the separator and is delivered through a pipe I! to a condenser l8 and the condensed refrigerant is then returned to the evaporator through a pipe IS. The liquid propellant is-thus circulated through an endless circuit and draws the vapor from the evaporator and isothermally compresses the same. In the apparatus shown in Fig. 1 the vapor is 'condensed (c1. lie-169) after it has been separated from the liquid but,

as will be hereinafter described, the vapor may be condensed prior to its separation from the liquid. The liquid propellant may be of .any suitable character but I prefer to' use a suitable oil or mercury, and any suitable refrigerant may be used which is immiscible with the liquid propellant, such, for example, as sulphur dioxid, and it is to be understood that the terms vapor and vaporized refrigerant as herein used are intended to include any compressible fluid which is suitable for the intended purpose.

The apparatus employed may take various forms and I have here shown the pump I3 asa centrifugal pump of the volute type. In a system of the kind here illustrated the impeller of the pump may, under certain conditionahave a diameter less than one inch, depending upon the refrigerant used and the condenser and evaporator pressures, and inasmuch as the ordinary centrifugal pump of the volute type, when built in small sizes, has a very low efliciency, I have provided a pump of special design which in small sizes will have a high efficiency and will discharge the liquid at the desired velocity, as will be hereinafter explained. As is customary in pumps of this type the pump casing has an axial inlet and a peripheral outlet '20 arranged tangentially to the impeller. In the present arrangement, the injector i2 is connected directly with the outlet of the pump and is of such a character that the pressure energy of the liquid discharged from the pump will be converted into velocity energy, thereby increasing the velocity of the flow of the liquid through the injector, and after the vapor has been intermingled with the liquid the flow v so proportioned that the pressure energy of the liquid is converted into velocity energy. The liquid passing through the inlet portion of the passageway is delivered into an intermediate portion of the passageway which, as shown at 22, is of a diameter somewhat greater than the diameter of the inner part of the inlet portion 2| and the vapor supply pipe ll communicates with this intermediate portion 22 of the passageway. The outlet portion 22 of the passageway has its inner end of a diameter approximately equal to the diameter of the intermediate portion 22 and is then gradually reduced to a somewhat smaller diameter. and then gradually enlarged to a diameter which is approximatelyfequal to the diameter of the pipe ll, as shown at 24. This shape of theoutlet portion of the passageway results in a constant rate of decleration' of the flow of the liquid and the conversion of the velocity energy into pressure energy. This in turn causes the vapor which has been intermingled with the liquid to be compressed therein between pressure limits determined by the shape of the injector and the increased pressure at the discharge end of the injector passageway will prevent the expansionof the vapor after it leaves the injector. Preferably the inner end of the inlet portion 2| of the passageway is slightly flared, as shown at 25, to cause the liquid to spread as it leaves the same and to be so agitated in the intermediate portion 22 of the passageway that the incoming vapor will be thoroughly intermingled therewith.

In some cases the relative locations of the various elements of the apparatus are of importance. The outlet of the pump should be located below the normal level of the liquid in the separator so that when the pump is idle it will be filled with liquid and vapor excluded therefrom. The injector which is connected with the pump outlet should be arranged at an inclination as shown so that when the pump is idle the liquid will drain from the injector into the pump casing and the injector should be so located that when the pump is idle the liquid will not rise in the injector any substantial distance, so that the vapor inlet and the outlet for the intermediate portion or mixing chamber 22 will be above the level of the liquid in the injector. Hence the inner end of the inlet passage 2| of the injector should be approximately on a level with the liquid in the separator. Means should also be provided to prevent the vapor flowing from the separator through the pipe II to the evaporator, and for this purpose the check valve llbhas been inserted in the pipe I I. This check' valve is-arranged above the injector so that the liquid from the injector will not drain into the check valve. It will also be noted that the injector is arranged some distance below the point at which the pipe II is connected with the upper end of the evaporator. Thus any oil or liquid which enters the evaporator along with the refrigerant and rises to the top of the refrigerant in the evaporator will eventually be drained from the evaporator to the injector and returned to, the liquid circuit.

The separator I5 may be of any suitable character but, as here shown, it comprises a closed receptacle having in its upper portion a bafle 26, and the pipe I4 enters the upp r end of the receptacle and discharges against the baiile, thus releasing the vapor and permitting it to separate from the liquid, which moves by gravity and pressure to the bottom of the receptacle. The heat of compression is absorbed by the liquid and should be extracted therefrom to prevent excessive rise of temperature due to repeated passages of the liquid through the injector, as the lower the temperature of compression the greater will be the pressure efficiency. It is therefore preferable that some means be provided for cooling the liquid before it is returned to the pump and thus maintain the same substantially at a constant predetermined temperature, and I have, in Fig. 1,

interposed in the return pipe I6 a radiator 21 about which the cooling medium may be circulated. Preferably the pressure of the liquid entering the pump is such that the pressure within the pump will be greater than atmospheric pressure and will prevent any leakage of air into the pump through its stufling box. The fact that the liquid surrounds the stuffing box prevents the escape therethrough of any refrigerant which may have entered the pump. The cooling medium may be circulated about the radiator 21 and the condenser l8 in any suitable manner, as by means of a motor operated fan 28. To prevent condensation of vapor within the refrigerant I prefer to maintain a liquid temperature slightly in excess of the temperature of vaporization of the vapor at condenser pressure. I may effect this higher temperature in any suitable manner, as by restricting the radiating surface of the radiator so as to insure the desired temperature, or I may pass the cooling medium about the radiator after it has passed about the condenser, as shown in Fig, l.

With the arrangement and mechanism here shown no expansion valve is required between the condenser and evaporator and no float valve is used in the evaporator but the condensed refrigerant is returned from the condenser directly to the evaporator substantially as fast as it is condensed and without passing the same through a receiver. It is, however, desirable that means be provided to maintain a pressure in the condenser sufllcient to effect condensation and for this purpose the conduit I9 which leads from the condenser to the evaporator is provided with a restricted portion or orifice, as shown at 30, which will maintain in the conduit above the orifice suflicient liquid to seal the orifice and prevent the escape of any substantial quantity of vapor through the conduit. When the pressure which is maintained in the evaporator is above atmospheric pressure the restricted oriflce alone is sufflcient for the purpose and when the apparatus is idle the pressure in the condenser and in the evaporator will be substantially equalized. However, when the pressure maintained in the evaporator is below atmospheric pressure it' is desirable to provide means to control the orifice so as to prevent the escape of vapor from the condenser to the evaporator and this is accomplished by providing a float operated valve to control the passage of refrigerant through the orifice ill and maintain a quantity of refrigerant above the orifice even though the pressure in the condenser is higher than the pressure in the evaporator. In the present arrangement the conduit is provided with an enlarged portion or receptacle 29, the orifice being arranged in the bottom of the receptacle and providing an outlettherefor. The valve 3i seats in the orifice and controls the flow of refrigerant through the same and is connected with a float 32 which actuates the same in accordance with the rise and fall of the refrigerant in the receptacle. In the arrangement shown the valve stemis slidably'mounted in a bracket 23 and the float is directly connected with the valve stem.

In larger systems economy is a factor and I I0 is ident'cal with that shown in Fig. 1, with the exception that a dlflerent method is employed for coolingthe liquid. In the second compressor unit the pump Ito, injector Ho and separator 15a are the same as. described above but the iniector is connected by a pipe Ila with the outlet "of the separator i5 of the first unit so that compressed vapors escaping from the first separator are againcompressed and delivered to the second separator, 'lSa, from which they escape through a pipe "a to a condenser 18a, which in the present instance is water, cooled. In the compression unit of Fig.,2 I'have shown means for extracting the heat of compression during thecompression operation, which means may be applied to either form of the apparatus. For this purpose the discharge end of the injector, in which the compression takes place, is water cooled, it being here shown as having the water chamber 34 surrounding the outlet portion of the passageway and provided with an inlet 34a and an outlet 34b,

whereby water may be circulated through the same.

As has been stated, the ordinary centrifugal pump of the volute type, when built for handling small quantities of liquid, has a very low efficiency and this efliciency is especially low if the pump is designed to pump a small quantity of liquid against a reasonably high head in contrast to a very low head. The low efliciency of such pumps.

- and therefore the efliciency of the pump decreases as the capacity of the pump decreases.

Another large loss in all centrifugal pumps of l the volute type is the loss ofvelocity energy within the volute. The normal velocityofflow of liquid within the volute of ordinary pumps is very low compared to the absolute velocity of the liquid as it is being discharged from the impeller into the volute, and as a consequence most of the velocity energy of the liquid as it is discharged into the volute from theimpeller is dissipated as the velocity is reduced to the normal velocity of flow within the volute. Formulas have been developedfor determining the best velocity of flow from an impeller into a volute in which the velocity of flow is neglible, but in the'be'st of de signs it is impossible to prevent large losses within the volute so long as the normal velocity of flow within the volute is small.

To eliminate the velocity energy losses within the volute the tangential component of the absolute velocity of entrance into the volute and the normal velocity flow within the volute must be substantially equal; and the radial component of the absolute velocity of entrance into the volute must be negligible. To meet these two conditions the tangential component of the absolute velocity of entrance into the volute and'the normal velocity of flow within the volute and-the peripheral velocityof the rim of the impeller must all be substantially the same; and the width of the I port into the volute, and the width between the crown plates of the impeller must be wide enough to insure such equality and at the sametime to insure a low radial velocity component, and to insure such velocity status the cross ,sectional area of the volute must be proper at all points.

To provide such velocity conditions the width between the crown plates of the impeller must be considerably more than is customary; the width from the axis of the impeller.

of the port into the volute must be considerably more than is customary; the cross sectional area of the volute at all points must be considerably smaller than is customary, and the velocity of flow within the volute must be considerablymore than is usual.

A serious objection to high normal velocity within the volutein standard pumps is fluid friction on the wallsof the volute, and another is that there is no way to utilize his high velocity energy, and as a consequence it is dissipated when it is "discharged from the pump even though it may not be dissipated when it enters the volute. For my purpose it is practicable to construct the pump from die castings, which may be made smooth inside,,and as a consequence friction loss within the volute will be small, especially when I use oil as a propellant. I,

In my apparatus I provide means for utilizing, properly, the normal velocity energy of the fluid within the volute, and as a consequence I do not lose it, and therefore my apparatus is such that I do not lose the velocity energy of the liquid that is lost in other centrifugal pumps of the volute type. By saving this velocity energy I am able to operate my pump at lowerspeed than other volute pumps are operated and with a smaller impeller, as the older pumps must have such greater speeds and diameters as will tend to make up this lost energy. This reduction in impeller speed and area is such that I am 'able to save most of the disc friction loss that is suffered in ordi nary small centrifugal pumps, and therefore when I provide means to save the loss of velocity energy within the volute I simultaneously provide means for reducing the disc friction, and thus provide a very eflicient pump regardless of its pumping capacity. 7 I

To overcome the objectionable featuresof orpump shown in Figs. 3 and 4. As there shown, the

- pump comprises a two part casing, the rear part of which is shaped to provide the rear wall 35 and the circumferential wall 36 of the casing. The other part of the casing forms the front wall. 31,

' and the two parts are rigidly connected one to the other, as by means of screws 38. The rear part of the casing has a rearwardly extending bossl 39 which is rigidly mounted on a supporting bracket 40 and has a longitudinal bore forming a bearing for the impeller shaft 4|, a stumng box 42 being. arranged about this shaft to prevent leakage. The front part of the casing has a forwardly extending boss 43 and the front wall 31 and the inner portion of this boss are provided with a relatively large cavity 44, while the outer portion of the boss is provided with an inlet passageway 45, with which is connected the return conduit it. The impeller is rotatably mounted in the space between the front and rear walls of the casing and comprises front and rear crown plates 46 and 41 which are connected one to the other by integral blades or vanes- 48, which extend inwardly from the periphery or rim .of the impeller but terminate at a considerable distance The rear crown plate 4'! has a boss 49 in which the shaft 4| is rigidly mounted, this boss preferably extending into a recess in the boss 39 of'the casing. The front crown plate has a boss 50 extending into the cavity 44 and .provided with a passageway 5| which communicates with and forms a continuation of the inlet passageway 45 and is flared in- I wardly so that its inner end has a diameter approximately equal to the distance between the inner ends of opposite blades. In the present arrangement a ring of anti-friction material 52 is mounted about the pusageway 45 in the boss 43 and the outer end of the boss 50 of the impeller bears against this ring, thus providing a substantially leak-tight connection that offers no substantial frictional resistance to the rotation of the impeller.

q The circumferential wall of the casing is shaped to provide a volute channel 53, herein referred to as the volute, which extends about the impeller and gradually increases in cross sectional area, toward the outlet 20, from a point just beyond the outlet. The rate of increase is comparatively small so that the volute has a relatively small capacity and the liquid will move through the same at relatively high velocity. The cross sectional area of this volute is directly proportional to the volume of liquid being pumped, as in the old form of pump, and for a given quantity of liquid it is also inversely proportional to the diameter of the impeller for a given angular velocity, and its cross sectional area is such that the velocity of the flow of the liquid therein will atall points be substantially constant and substantially equal to the tangential component of the absolute velocity of the liquid discharged from the impeller into the volute. When the surface of the volute channel is smooth, as when the casing is formed of die castings, the frictional resistance to the flow of the liquid is reduced so that the velocity of flow may to advantage be substantiallyequal to the peripheralvelocity of the rim of the impeller. The volute may be of any suitable cross sectional shape and, in the present instance, it is rectangular in cross section so that the open inner side of the volute, which forms the inlet port for the same, is of 'a width'equal to the greatest width of the volute and the cross sectional area of the volute is proportional to its depth, which increases slowly toward the pump outlet.

The width of the outlet from the impeller, which in the present instance is determined by the distance between the crown plates, is not less than the width of the inlet port for the volute. This outlet may be of a width greaterthan the width of the inlet port without materially affecting the efliciency of the pump and I prefer that the outlet shall be of a width slightly greater than the volute port to take care of any inaccuracies in manufacture or any axial displacement of the impeller. The capacity of the impeller outlet results in the liquid being discharged from the impeller at negligible radial velocity. The blades 48 may be arranged in any suitable manner but I prefer that they should be approximately radial, instead of being backwardly curved as in the old type of pump. In the present instance, they have a slight forward curvature but are substantially radial at the rim oi: the impeller. The absolute radial velocity of the liquid discharged from the impeller being negligible the absolute tangential velocity, which is in the direction of the flow of the liquid in the volute, will represent substantially the total velocity of the liquid discharged from the impeller, and this liquid is discharged into a body of liquid in the volute which is moving at a high velocity. Consequently the velocity loss due to frictional contact between the impeller and the liquid, and the power required to operate the pump is very small. With small pumps an ordinary fan motor may be used for this purpose if desired. The parts of the pump are of such a character that they may be made by die casting, and are easily assembled. Thus the pump can be manufactured at a very low cost and operated at a very low cost and with a high degree of efiiciency.

It will be understood that while the pump is designed primarily for use in the refrigerating system here illustrated, for which purpose it is peculiarly adapted, it is also capable of use for various purposes, and any suitable discharge nozzle may be substituted for the injector l2. In Fig. 6 I have shown the pump as provided with a discharge nozzle adapted to convert velocity energy into pressure energy, for use when it is desirable to have such pressure energy, and by means of this nozzle I am able to prevent dissipation of the velocity energy of the liquid within the volute.

In Fig. 5 of the drawings I have shown a further modification of the apparatus. In this apparatus the vapor is condensed, as well as compressed, within the injector, and the separator is designed to separate the condensed vapor from the circulating liquid instead of separating uncondensed vapor from the circulating liquid as in the other apparatus heretofore described.

To effect condensation within the injector it is essential, first, that the injector be proportioned to compensate fdr such condensation, and, second, that within the injector the pressure he brought finally to, or preferably slightly above, the pressure corresponding to a temperature of vaporization equal to the temperature of the circulating liquid.

This form of apparatus, of course, is operable only under conditions which will permit of proper separation of the condensed vapor from the circulating liquid, and if this separation is to be eiTected in a practicable mechanical way it is essential that the specific gravities of the condensate and the circulating fluid shall difler; the more they differ the easier the separation.

With this form of apparatus I do not need a separate condenser as in the form shown in Fig. 1. Instead I need a radiator which is suiliciently large to insure radiation of the heat of vaporization of the vapor as well as the heat of compression.

In this apparatus the injector 55 is connected with the outlet of the pump 56 and with a conduit 51 which leads to a separator 58, the separator being connected by a return pipe 59 with the intake of the pump. The evaporator, which is here shown as a col] Oil, is connected by a pipe 6| with the injector and by a return pipe 62 with the separator 58.

During the compression and condensation process the temperaturebf the circulating medium tends to warm slightly; and to effect condensation within the injector the pressure must be correspondingly raised above the pressure within the separator, as condensation cannot be effected within the injector if the pressure in the discharge conduit 51 is below the pressure that corresponds to this slightly higher temperature. To effect this increment in pressure I place a slight restriction in the discharge conduit, as shown at 64; Instead of the restriction I could cause this slight increment in pressure by decreasing the general size of the discharge conduit and thus increasing the I friction therein. For the vapor to remain in the condensed form it is necessary that the circulating liquid be cooled prior to reduction of pressure, and therefore it is essential that the radiator coil 63 be placed between the injector and the restriction 64. v

With the type of separator shown at 58 it is essential that the condensate have a higher specific gravity than the circulating liquid. Such a separator would serve well for separating sulphur dioxid from oil. If the circulating liquid was heavier than the condensed refrigerant the circulating liquid would be returned to the pump from the bottom of the separator instead of from the higher point shown, and the refrigerant would be discharged from a higher point instead of from the bottom as shown; that is, the refrigerant would float on the circulating liquid instead of the circulating liquid floating on the condensate, and the outlets would have to be rearranged accordingly. When mercury is used as a circulating medium with any refrigerant the outlets would have to be rearranged accordingly because of the ,high specific gravity of mercury as compared to all refrigerants.

While in Fig. I have shown the direct expansion system, with an expansion valve 65 in the conduit 62, it is apparent that I could use the seal system shown in Fig. 1, or the standard flooded system with the float control within the evaporator.

While I have shown my preferred apparatus I wish it to be understood that I do not desire to be limited to the details of the apparatus as various modifications may occur to a person skilled in the art.

Having now fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a refrigerating apparatus, an evaporator, a pump for circulating a liquid, a separatona conduit connecting the outlet of said pump with said separator, means for delivering vaporized refrigerant from said evaporator to said conduit and for causing the same to be compressed by the liquid therein and carried by said liquid to said separator, a return conduit leading from said sepa- 5 said condenser to said evaporator.

2. In a refrigerating apparatus, an evaporator,

a pump, an injector connected'with said pump to receive liquid therefrom, means for delivering vapor from said evaporator to said injector, said injector being shaped to cause the liquid passing through the same to compress the vapor therein, a separator arranged to receive the liquid and vapor from said injector and comprising a chamber to maintain the liquid under pressure and means within said chamber to spread said liquid and change the direction of flow thereof to separate the compressed vapor from said liquid, a conduit to return the liquid from said separator to said pump, a condenser connected with said separator to receive the separated vapor therefrom and condense the same, and means for returning the condensed vapor to said evaporator.

3. In a refrigerating apparatus, an evaporator, a pump, an injector connected with said pump to receive liquid therefrom, means for delivering vapor from said evaporator to said injector, said injector being shaped to cause the liquid passing through the same to compress the vapor therein, a separator arranged to receive the liquid and vapor from said injector and comprising a chamber to maintain the liquid under pressure, and means within said chamber to spread said liquid and change the direction of flow thereof to separate the compressed vapor from said liquid, a conduit to return .the liquid from said separator to said pump, a condenser connected with said separator to receive the separated vapor therefrom and condense the same, means for returning the condensed vapor to said evaporator, and means for automatically preventing the backflow of said vapor from said separator to said evaporator when said pump is idle. I

4. In a refrigerating apparatus, an evaporator, a pump, an injector connected with said pump to receive liquid therefrom, means for delivering vapor from said evaporator to said injector, said injector being shaped to cause the liquid passing through the same to compress the vapor therein, a separator arranged to receive the liquid and vapor from said injector and comprising a chamber to maintain the liquid under pressure and having means for separating the compressed vapor from said liquid, a conduit to return'the liquid from said separator to said pump, a condenser connected with said separator to receive the separated vapor therefrom and condense the same, means for returning the condensed vapor.

to said evaporator, and means for automatically preventing the back flow of saidvapor from said separator to said evaporator when said pump is idle.

' EDWARD T. TURNER.

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