US2023435A - Refrigeration - Google Patents

Description

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Patented Dec. 1o, 1935 UNITED STATES PATENT IOFFICE REFRIGEBATION Frank Desnoyers PeltierV and Clyde Edward Ploeger, Evansville, Ind., assignors to Servel Inc., New York, N. Y., a corporation of Dela- Wale v2 claims. (ci. sz-ss) This application is a. division of our co-pending application KSerial No. 290,871, i'lled July 6th, 1928, and is to be considered as relating back to applications Serial Nos. 152,339 and 152,902, for common subject matter and to the rights incident thereto.

Our invention relates to refrigerating apparatus and more particularly to the type of apparatus embodyingv a closed cycle including compressor,

Still more particularly our invention relates to the evaporator of such a system.

Amongst various objects of our invention are: To produce a novel cycle of ilow for refrigerant uid; to provide a novel method and apparatus for lubricating a refrigeration system and for conducting lubricant within refrigeration apparatus; the simplication of manufacturing andy standardizingl of refrigerating equipment; an y improved multiple system of refrigeration; a system of refrigeration which is simple in number and construction of parts, the parts of which are of such nature and so devised that the apparatus as a whole is more rugged and less liable to get out of order than previous devices of this `class while maintaining a higher/efficiency of operation; to produce a direct and' positive low of refrigerant with advantages accruing thereto while controlling the ow in a manner such that refrigeration is produced in an efficient manner independently of the parts of the system collateral to evaporation; to positively return refrigerant from a float valve chamber to the compressor; to provide an arrangement wherein a standard manifold may be used with various lengths of tubing for diiferent refrigerative capacities; and in general to improve the operation of refrigerating apparatus.

With the above and other objects in view, the invention consists in the novel features of construction, arrangement of parts and combinations of elements hereinafter described and'such variations thereof asfall within the scope and spiritof invention and methods and processes involved in the operation of such apparatus.

The invention is described with reference to the accompanying drawings of which:

Fig. 1 shows more or less diagrammatically a refrigeration system embodying the principles of invention with novel parts shown more in detail;

Fig. 2 shows the system of Fig. 1 and in addition thereto means for returning lubricant from the evaporator to the compressor;

Fig. 3 shows, on an enlarged scalethe conl struction of a part of the apparatus of Fig. 2;

Fig. 4 shows a modification of the lubricant return means;

Fig. 5 shows another modification of the lubricant return means;

Fig 6 shows a modication of apressure drop member forming part of the lubricant return means;

Fig. '7 is a top view of an evaporator assembly embodying various inventive features;

Fig. 8 is a front view of the evaporator assembly of Fig. '7 shown suspended in a refrigerator cabinet;

Fig. 9 is a cross-section oi a part of the apparatus of Fig. 7;

Fig. 10 is a side view of the evaporator assemblyof Fig.8; Fig. 11 shows the lubricant return means of Fig. 2 applied to a different form of evaporator;

Fig. 12 shows a multiple system with evaporator sections connected in series;

Fig. 12a is a top view of a part of one of sections or Fig. 12;

Fig. 13 shows a multiple system with evaporator units connected in parallel;

Fig. 14 shows'a preferred form of manifold shell; and

Fig. 15 shows an adjustment for the oriiice.

Referring more particularly to Fig. l, an electric motor 2. drives compressor 3. 'Compressor 3 receives expanded gaseous refrigerant from the conduit 24 and supplies compressed refrigerant 4 is connected by means of conduit 'l with a 35 valve member 23. Valve member 23 has a central passageway 21 Whichconstitutes a portion oi a continuous passageway, a part of which is within the end head Il of float manifold l0, said passage .being indicated at 25. Passageway 26 is connected to evaporator coil I5. Evaporator coil I5 is formed of one continuous pipe and its outlet end is connected to a pasageway 30 formed within the other head I6 of oat manifold ill, opposite to head Il. The parts hereafter described are also embodied in the apparatus shown in Fig. 3 to which reference may also be had.

Valve member 23 Y gis screwed into a recess 28 formed in head I I. The end of passage 21, which is preferably restricted as shown in Fig. 3, con-- stitutes a valve seat indicated at 3|. Valve seat 3| cooperates with a needle valve 22. Recess 28 is formed at right angles to passage 26. Needle valve 22 is formed on the end of an extended stem '32. Stem 32 is also arranged at right en /55 gles to passageway 26. Needle valve 22 is movable in response to variations of level of liquid Within manifold I0, which variations of level are transmitted to the needle valve by means of a float I8 resting upon the surface of liquid within the float chamber. This movement is transmitted through lever I9, bell-crank 20 and link 2|. Float I8 is attached to lever I9 which is in turn attached to bell-crank 20 pivoted at 4U on an arm 4I. Bell-crank 20 is connected to link 2I and link 2I is in turn pivotally connected to stem 32 of the needle valve 22. Stem 32 passes with relatively loose t, but at the same time closely, through a passage or bore 34 which connects the inner liquid and vapor space of oat manifold I with passage 26. The tightness of stem 32 may be determined in accordance with the desired balance of leakage and frictional resistance.

By arranging the conduit from the condenser to the evaporator in part within head II, it is possible to control needle valve 22 and thus control this conduit by a simple arrangement needing no stung boxes, or bellows, or other friction-producing or strained part. The amount of leakage along passage 34 outside stem 32 is of negligible quantity. By permitting this slight leakage, a simple construction is obtained. By arranging the condenser-evaporator connection in part within the head no leakage is possible from out of the system as a whole.

Head II has an opening I2 for the reception of return conduit 24 which is connected to the intake of the compressor. In conduit 24 is inserted pressure control switch 6 which may be of known type and which starts and stops the motor-on predetermined rise and fall of suction pressure. It will be understood that the system is not limited to any particular type of control of the motor. Thermostatic control may be used as well as pressure control.

Reference character 9 designates a refrigerator cabinet having insulated walls bounding the space to be cooled. The evaporator assembly, including manifold I0 with its heads II and i6 and coil I5, is entirely placed within the cabinet 9 in the space to be cooled.

The mode of operation of the system shovm in Fig. 1 is as follows:

Gaseous refrigerant, such, for example, as methylchloride, compressed in compressor 3 passes into condenser 4 where it is liqueed and thence passes through conduit 'I and into passage 2'I, assuming that needle valve 22 is away from seat 3I so that the valve passage is open. Assuming needle valve 22 to be open, liquid refrigerant passes into coil I5 and a portion thereof is evaporated. Evaporation absorbs heat from the surroundings and produces refrigeration. A mixture of vaporous refrigerant and liquid refrigerant passes through passageway 30 and into the float manifold. The rise of liquid quantity within the float manifold causes a lifting of float I8 and this operates, through the mechanism above described, to close needle valve 22 against seat 3| to a greater or lesser extent, thus diminishing the ow of liquid refrigerant into the evaporator'. If needle valve 22 is entirely closed, no liquid refrigerant passes from the condenser through passage 21 and into the evaporator.

Assume now that needle valve 22 is closed and that the control mechanism has stopped the motor and compressor. As the space to be cooled becomes warmer evaporation takes place in manifold I 0. This increases the pressure so that the motor is started and at the same time lowers the liquid level so that more liquid refrigerant is admitted into the evaporator. Float I8 thus operates to maintain a constant, or substan- 5 tlally constant, level of liquid within manifold I0. It will be noted that both manifold Il) and coil I5 partake in evaporation and therefore these two members together may be said to constitute the evaporator.

By means of the arrangement above described a direct positive flow is obtained through the evaporator coil. At the same time the arrangement is such that the evaporator coil is susceptible to various configurations. The advantage of i5 positiveness of float control is obtained in combination with the other features of positive ilow and adaptability of structural formation.

In order to take care of lubricant for the refrigeration system above outlined, we have devised the arrangement shown in Fig. 2 which is particularly suited to cooperate with the system above dened. In Figs. 1, 2 and 3 like reference characters designate like parts. The system in general will be understood from the above de- 25 scription. In Fig. 2 tube 26, connected to the suction side of the compressor, is extended through head II into manifold I within the vapor space thereof. Within tube 24 is situated a restricted portion 3l. This restricted portion, in 30 the embodiment shown, is formed as the contracted portion of a Venturi tube 25. The Venturi tube has a gradually contracting passageway towards the restricted portion and a gradually expanding passageway away from the restricted portion as is characteristic with Venturi tubes. The restricted portion of the Venturi tube, otherwise known as the throat, has connected thereto a tube 26 of relatively small internal diameter or bore which extends below the surface level of liquid refrigerant within manifold I0.

The system in Figs. 2 and 3 is intended to contain a refrigerant and a lubricant of such nature that, in operation, the lubricant is dissolved in, or is emulsified in, the refrigerant. Methylchloride is preferably used as the refrigerant and a mineral oil as the lubricant.

In the system shown in Fig. l, without any means for taking care of lubricant, and with lubricant contained in the system intended to go through the complete cycle, lubricant would assemble in the manifold ID. This lubricant is removed by the arrangement of Figs. 2 and 3. As the vapor passes out of Venturi tube 25 when 55 drawn by the compressor an increase in velocity is produced at throat 3l and there is a corresponding drop in pressure at this point which produces a suction acting through tube 26. This suction causes liquid to flow through tube 26 and 60 into conduit 24 and thence on to the compressor. The liquid passing through tube 26 is composed partly of refrigerant and partly of dissolved or suspended oil. The uid passing through conduit 24 passes through evaporator coil 2'I where 65 the liquid refrigerant carried over through the suction line is entirely vaporized and passes into the suction line proper as a gas together with the separated liquid oil which it formerly held in solution or suspension. Coil 2l is within the 70 space to be cooled and is a secondary evaporator.

It might be called a tail coil or a drying coil. With the apparatus shown it will be understood that the oil cannot accumulate in evaporator coil I5 as a positive ow is created through this 75 coil. The oil is made to accumulate in the oat manifold i@ from which the arrangement including parts 25 and 26 draws the oil back to the compressor. It will thus be seen that our novel oil return is particularly well adapted to cooperate with the system comprising the continuous coil i5 having the ends thereof isolated and a oat at a discharge end controlling avalve at the inlet end.

The oil entering the evaporating section with the refrigerant accumulates within the manifold Ill and the concentration of oil in the manifold increases at the beginning of operation untilt 'a point is reached where the oil drawn through tube 26 equals the entrained oil entering the evaporator section. Our arrangement therefore automatically maintains a proper flow of lubricant.

I'he invention is not limited to suspended or dissolved lubricant. Fig. 4 shows an arrangement adapted for use in a system employing sulphur dioxide as a refrigerant and having as a lubricant an oil .which is lighter than sulphur dioxide and which floats on the top of the same. In this case tube 2E is extended to the surface of liquid in the manifold i and the suction in the Venturi tube draws the oil from the surface. By using a tube 26 extending to the bottom of manifold i@ as shown in Fig. 5, the invention isapplicable to a refrigerating system using ethylchloride or methyl-chloride with glycerine as a lubricant, glycerine being heavier than ethylchloride or methyl-chiari le and insoluble therein.

in either or the two cases illustrated in Figs. 4i and 5 the second evaporator '2li is probably not necessary as there would not be sufficient liquid refrigerant entrained by theA lubricant and sucked up through tube 2u to the return line tothe suction side of the compressor to require a second evaporator. in these cases opening le may be connected directly by a pipe to the suction side of the compressor. In any case, it is not desired, however, with a reciprocating type of compressor, to carry liquid refrigerant into the compressor.

In Fig. 2 we have shown the motor 2 as controlled by a thermostatic mechanism comprising a bulb l2 connected by tubing t3 to a bellows ltd, the bulb, tubing and bellows containing a vaporizable uuid and comprising a switch te responsive to vaporization of fluid in bulb 42, situ= ated in the space to be cooled, for closing and opening the motor circuit. kAs in the previous case the evaporator is entirely placed within the space to be cooled so that evaporation may take place in manifold I0 due to heat supplied from the surrounding space to be cooled. It will be noted that the liquid within manifold it is in direct heat transmitting relation with the cir culating air of the space to be cooled.

Fig. 6 shows a restriction or orifice 46 which may be used for the same purpose as the Venturi tube of conduit 24. When an orifice is used the tube 26 communicates with conduit 24 a short distance in the direction of flow beyond the orifice 46. The use of an orifice causes a permanent pressure drop in the outlet conduit beyond the orice. Such connection has also an asperating effect. y

Figs. 7, 8, 9 and l() show an evaporator assembly as built embodying the features of invention above described. The parts corresponding to like parts of previous figures are designated with like reference characters. The evaporator assembly comprises the `manifold lll, the primary -ments.

'leading from the condenser is connected to mem- 10 ber 5i. A strainer 52 is placed Within member 53 which is in effect a part of head Il of manifold tu. The arrangement of needle valve 22 and its connection Wlth'oat i8 is substantially as above described. The needle valve stern 32 is 15 provided with a series of grooves 5d which serve to diminish leakage past the stem from the inside of manifold l0 to the liquid supply passage. Manifold i@ is provided with circumferentially extending. axial fins 5b which serve to transmit 20 heat from the surrounding atmosphere to the liquid Within the manifold. Liquid refrigerant passes through' passage 2l, past needle valve 22 and into the inlet end of coil i5 which is looped as indicated at 5l. After passing through coil l5 25 refrigerant is discharged through connection 58 into the interior of manifold it.

lf desired, orice it may be made adjustable from the outside of the system by using a valvelike member having a stem extending through a 3o suitable in: g box which can be moved to regulate the size of the orice opening so that the suction acting through tube 26 may be regulated in order that the proper amount of liquid may be withdrawn from manifold iii. Conduit 2t' is g5 connected beyond orice it in the line of iiow as has been explained in connection with Fig. 6 and hence, by decreasing the size of the orifice the suction in tube 2t will be increased. Thus, for example, in a multiple installation, as is shown 40" in Fig. 13, Where the pressure in the diierent. return conduits 2d adjacent the respective"evapo`- rators may be different on account of the different distances vvhich the evaporators are from the compressor, the orifices le in the different evaporators may be so adjusted that the suction acting through the respective tubes 2t may be the same for each tube. The outlet end t@ of tail coil' 2li is connected to the suction side of the compressor.

We prefer to use methyl-chloride and a mineral oil in the arrangement of Figs. 7, d, 9 and l0 as in the case of the previously described embodie operation will be clear from the above description taken in connection with the description of previous modifications.

in Fig ll we show the oil return of Fig. 2 applied to a loop type of evaporator as distinguished from the series coil type of evaporator of Fig. 2. In Fig. 1l manifold I0 has a series of loops 6I de- 60 pending from the bottom thereof. The liquid line i discharges directly into manifold l0 without first going through an evaporator coil. In the arrangement of Fig. 11 the total drop in pressure between the liquid line and manifold I0 takes 65 place through needle valve 22, whereas in the previous embodiments some of the pressure drop takes place through vthe needle valve 22 and some through the evaporator coil. 'Ihe oil return mechanism removes oil or lubricant from manifold il) in much the same manner as in connection 'with the previous embodiments. It will be seen that the lubricant return mechanism is not confined to the series coil type of evaporator previously described. However, we prefer it in combination with the same because, in the apparatus of Fig. 11, the oil return device can not so well take care of lubricant which is contained in loops 6I whereas in the arrangement of Fig. 2 there is 5 -a continuous force circulation through coil I5 which is certain to carry the oil over into manifold I0 and to the vicinity of the inlet opening of pipe 26. If desired, ice trays may be placed Within loop 6I of Fig. 11 in Well known manner 10 and the manifold shell may be equipped with fins.

It has been above stated that the arrangement in Figs. 1 and 2 with the coil I5 may be of various lengths and configurations. In Fig. 12 we have shown an evaporator assembly wherein a 15 plurality of sections 62, 63 and 64 are connected in series by means of conduits 65 and 66 and connected by means of conduits 61 and SB with manifold I0. The manifold is of substantially the same construction as in the modifications above described. Sections 62 and 63 are alike and comprise a tube 1U shaped in the form of an S and to which are attached flue forming members Il and 12. These are shown in Fig. 12a. Section 64 is similar to sections 62 and 63 but isof smaller size.

The arrangement shown in Fig. 12 is intended for refrigeration in larger cabinets than the household type. This adaptation is particularly applicable to so-called commercial installations.

, While household units can .be designed for standard refrigerative effects, the requirements of commercial Work necessitate different evaporator surfaces and different capacities. Dur invention permits a ready adaptation to different capacities for commercial work. Our system is of the flooded type or, probably more correctly, the semi-flooded type. Flooded systems usually em ploy a float valve which gives a more definite control than that type of valve which is generally known as expansion valve used on dry systems. In previous arrangements embodying the use of a float valve complications have arisen which were overcome by means of the present invention. With the adoption of float control for the supply of refrigerant to the evaporator, the float and.

evaporating surface have generally been combined in aunitary structure. The float being in the low pressure evaporator space, this has been deemed necessary or most expedient. The result has been that where different loads are concerned, either complete evaporator units, including floats, must be used or a number of complete units, each with a separate' float, must be used. 'I'he dealer or distributor of refrigerating material of this type either generally has on hand a great number of different sizes of different capacity evaporators, each including evaporating surface and float, the different sizes being proportionately graded for different capacities.

By means of the present invention we are able to isolate the oat and the float valve in a separate manifold and one size of manifold is suitable for all capacities of evaporator units regardless of differences of capacities. Furthermore the manifold may be used with different sizes and shapes of evaporator tubing. The type of evaporator tubing shown in Fig. 12 is a known commercial product. It will be evident that various types of tubing and extended surfaces, therefore,

. may be used. With this system the distributor need only have a few manifolds on hand all of the same size, and a series of standard evaporator sections such, for example, as shown at 62 and 6I, with possibly a small number of odd sized sections such, for example, as shown at 64.

It will be evident that sections 62, 63 and 64 may be placed alongside of each other in parallel. This would probably be the preferable arrangement in the average cabinet. They can be placed in aline, as shown in Fig. 12, which would 5 be the preferred way for certain show-case installations having an extended evaporator in the compartment ordinarily used for ice. For this purpose the arrangement shown in Fig. 12 is particularly suitable asl it gives a series of vertical 10 flues formed by the member I I, 12.

The operation of the apparatus of Fig. l2 is the same as that in previous modifications. This modification includes the oil return device and the tail coil 21 for evaporating any refrigerant 15 entrained into pipe 26 or otherwise carried from the manifold in direction toward the compressor.

Referring to Fig. 13 the apparatus described above is shown in an arrangement suitable for use with a plurality of evaporators. As shown, 20 one condenser is employed but it is to be understood that a separate condenser may be employed for each evaporator, or two evaporators supplied from one condenser and one evaporator from another condenser, or any such combina- 25 tions of condensers and evaporators may be employed without departing from the spirit of the invention. Also, any number of evaporators may be used, three merely being a convenient number for illustration. 30

. Compressed gaseous refrigerant leaves the compressor through conduit 25, is liquefied by condenser 4 and passes into pipe 5. During its passage through pipe 5 the liquid refrigerant divides and passes through the various pipes de- 35 noted by reference character 1. From conduits AI the refrigerant passes through respective oat actuated expansion valves, evaporators I5 and manifolds I0 in the same manner as previously described with reference to a single manifold 40 system. The amount of liquid refrigerant entering each evaporator coil through the expansion valve used in connection with that coil is dependent on the liquid level in the iioat chamber of that oat actuated expansion valve and is in- 45 dependent of the liquid level in any of the float chambers or any other conditions existing in the system.

The vaporous refrigerant after leaving manifold I0 passes through the respective pipes 24 50 to a common return pipe I4 which is connected to the suction side of the compressor. Interposed in this pipe I4 may be the pressure control switch 6 used to start and stop the motor at predetermined valuations of pressure in the suction line. 55

Fig. 14 shows a preferred form of shell for manifold Ill. The shell is made of a single brass plate and is drawn to the form shown making a single unitary drawn member composing the major portion of the manifold. The ange por- 60 tion 16 is connected to a suitable head containing the needle valve and supporting the float. The opening 'l1 serves for the reception of a member containing the conduits connected to the manifold at that end. 65

Fig. 15 shows an outside adjustment for the orifice as above referred to. I0 designates the manifold shell and 26 designates the tube connecting the liquid space of the manifold with the reduced pressure space of the return line 70 from the manifold toward Athe compressor. The orifice member 46 is situated in a sleeve 'I9 which is fitted into the opening 'I1 of Fig. 14. A spindle I8 carries a valve 80 which is adapted to be moved into and out of the orice to change its 75 engages size. Stern le is connected to a'threaded portion ti which is adapted to be screwed into member le. Packing 82 is inserted between a ring @t and a threaded retaining member 6d. A cap d5 :dts over the end of member le. te designates a threaded opening for a connection to the suction line leading to the compressor. This type of adjustment or similar adjustments may be applied to the orifices of any 'of the previously described embodiments of the invention.

While we have shown and described various embodiments of our invention, it will be understood that we are not limited to the apparatus shown or described but that a great many valiations are permissible within the spirit and scope of the invention.

Having thus described our invention, what we claim is:

l. A refrigerator comprising a cabinet having insulated bounding Walls defining a space to be cooled, an evaporator within said space comprising a manifold having an outer shell and providing a chamber for containing a body of liquid refrigerant, a passageway for liquid refrigerant extending within said shell and separated from said chamber, a valve in said passageway, means responsive to variations of surface level ci liquid in said chamber for moving said valve to vary dow ci liquid refrigerant through said passageway, evaporator tubing connected 5 to said passageway and arranged to conduct iluid from said passageway to said chamber, said tubing comprising a series of standard sections each made up of 'tubing with members forming extended surfaces attached thereto, said memm bers forming flues for passage of air past the tubing, said tubing passing through the space to be cooled and said shell acting to transmit heat from the space to be cooled directly to the body of liquid in said chamber. 15 2. A refrigerator comprising a cabinet having insulated bounding walls dening a space to be cooled, an evaporator Within said space compricing a manifold, tubing .connected to said manifold and a tail coil connected to receive 20 vapor and liquid from said manifold, said tail coil being situated in the space to be cooled to evaporate refrigerant therein.

FRANK DESNOYERS PELTIER. CLYDE EDWARD PLOEGER. 25

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