US1846608A - Heat exchanger for refrigerating machines and the like - Google Patents

Description

Feb. 23, 1932. G. H PHELPS 1,846,603

HEAT EXCHANGER FOR REFRIGERATING MACHINES AND THE LIKE Original Filed Oct. 12. I926 2 Sheets-Sheet 1 anoentoz GEO/qr: [Z 1 /151125;

Feb. 23, 1932. s. H. PHELPS 1,846,608

I HEAT EXCHANGER FOR REFRIGERATING MACHINES AND THE LIKE Original Filed Oct. 12, 1926 .2 Sheets5heet 2 avwemtoz OEO/PGEH 315L1 3 Patented Feb. 23, 1932 UNITED STATES PATENT OFFICE GEOBGE'H. PHELPS, OI WAREHOUSE POINT, CONNECTICUT, ASSIGNOR, BY MESNE AS- BIGNMENTS, TO METROPOLITAN ENGINEERING CORPORATION, A CORPORATION OF NEW YORK HEAT EXCHANGEB FOR BEFRIGERATING MACHINES AND THE LIKE Original application fled Octobei- 12, 1926, Serial No. 141,065. Divided and thin application filed October 9, 1828. Serial No. 811,292.

In application No. 141,065 filed October 12, 1926, I have described certain refrigerating mechanism. The present application is a division thereof based on the heatexchanger or condenser and related features. The accompanying drawings illustrate embodiments of the invention.

Fig. 1 is a plan view of the principal parts of the apparatus;

Fig. 2 is a plan of the base shown in Fig. 1 within which is the condenser shown diagrammatically in dotted lines;

Fig. 3 is a plan of the same with the cover of the casing removed;

Fig. 4 is an end view of the same with the casing in place;

Fig. 5 is a section on the line 55 of Fig 3;

ig. 6 is a perspective view of a radiating structure;

Fig. 7 is a view similar to Fig. 4 showing an alternative construction.

Referring to the drawings, on a common base there is mounted a motor 1 which drives a rotary blower 2 and a rotary compressor 3. The blower has air inlets 4 and an outlet at the bottom indicated in dotted lines at 5 in Fig. 1. The refrigerant gas from the compressor 3 passes by a pipe 6 and branches 7 and 8 downward to the condenser, thence upward through an outlet pipe 9 to the refrigerating cabinet, whence it is piped back to an inlet 10 of the compressor. The rotary blower and compressor may be replaced by various known equivalent means for making a current of air and for circulating the refrigerant. A cut-01f switch is used to automatically start and stop the motor according to the temperature of the ice-box, but this and other accessories are unessential to the present invention and are not illustrated. With such apparatus, the condenser has generally consisted of a coil of copper tubing through which air under pressure has been circulated.

I provide a condenser and an arrangement thereof by which the refrigerating machine can be made much more compact and efficient than those heretofore used.

The condenser has a steel housing consisting of a top plate 11, a bottom plate 12 and side plates 13 (Fig. 4) and is open at opposite ends. This complete condenser in its housing is used as a base on which the principal parts of the machine are mounted, thus efl'ecting a saving of space in addition to that due to the compactness of the condenser, and saving the extra expense of a separate base.

The efiiciency is increased by providing the tubing of the condenser with fins or a radiating structure which conducts the heat away from the circulating gas and liquid and transfers it to the air which is blown through the condenser. Various types of radiating structures may be used. But I have shown a ty e which is highly efficient and which can be easily and economically applied.

This structure is made of a plate or plates of conducting material, such for example as copper or tin plate, very thin and bent backward and forward in end view to form a succession of fins 14 converging alternatively at top and bottom with a slight space between them at their near points so as to expose the entire surface. A radiating structure of this sort' provides longitudinal channels through which the cooling current of air is forced. For making contact with the tube through which the refrigerant is circulated, the plates 15 which connect the fins 14 are depressed at intervals to form recesses or grooves 16 and 17 (Fig. 6) in the opposite parallel faces of the structure. The tubing is laid in these recesses and intimately united or bonded thereto by heat and pressure, as by soldering or brazing or welding for example. The structure described can beformed in dies, first bending the fin portions 14 to parallel positions and then bending up the recesses 16 and 17, and finally bending the fin portions to the oblique positions shown.

Two such radiating structures, each designated as a whole by the numeral 18, are set in the casing with the flues between them extending lengthwise of the casing and with a slight separation between their inner ends as shown in Figs. 2 and 3 so as to leave room for the entrance of the air at the centre (through the outlet 5 of the blower) whence it passes in opposite directions through the bent alternately in vertica two condensing units as shown by the arrows A in Fig. 2.

The tubing is applied in such a way as to form traps which will separate the liquid from the gas. For this purpose it is arranged in two planes near the to and bottom faces respectively of the radiating structure, being and horizontal lanes. See Fig. 3. The gas follows the path indicated by the lines B in'Fig. 2. Entering from the branches 7 and 8, it travels along the length 19 of tubing on the top of the radiating structure. At the opposite side of this structure it bends down as at 20 and returns along the length 21 (Fig. 4) near the bottom face of the radiating structure. The forward end of the length 21 bends as at 22 (Fig. 3) in a horizontal direction, passing alon the bottom of the radiating structure para lel with the len th 21 and thence upward and across the top ace parallel with 19 and so on. Thus the tubing is in loops on one side of the corrugated sheet and in other loops on the opposite side, the successive loops being first on one side and then on the other. The successive loops are connected by the bends 20. These are located at one side only of the structure. At the opposite side, shown in Fig. 5, there is a space between the 100 s. This is important in the manufacture of t e apparatus, permitting the insertion of the corrugated sheet between the loops of tubing by sprin 'ngthe loops referred to slightly apart. hey are then released and pressed into the recesses 17 and held in heat conducting contact therewith b any usual or suitable means. The portion 0 the tube in each half of the condenserends with a branch 23 and these two branches communicate with an outlet pipe 24 which passes to the outlet 9 previously referred to.

The drops of liquid formed as the gas be- 'ns to condense collect in the tubes on the ower level (which constitute the traps referred to) and toward the end of the tubing in each unit fill the lengths on the lower level and the outlet pi e 24. In fact the last part of the piping at 0th levels will generally be filled with the liquid in a column pressed forward by the gas behind it. It is this liquid in the condenser which is acted upon first by the incomin air, the coolest air available, and is there ore cooled to as great an extent as is practicable.

It is an important function of condensers in refrigerating machines that they shall not only condense the gas but shall also send the liquefied refrigerant to the cabinet as cool as is possible. To do this, we must first segregate the liquid from the gas. The liquid cannot be cooled while in free contact with the gas; there would simply be a condensation of more gas to increase the quantity of liquid at substantially the same temperature. By the trapping or segregating arrangement which I have shown and the counterflow arrangement of the air and the refrigerant, the maximum coolness of the liquid is obtained. A substantial fraction, probably one-fourth to one-half of the condenser, o crates to cool the liquid and the remainder o it to condense the gas into liquid form.

In the end view, Fig. 4, there are shown strips 25 of felt or similar packing which prevent the air from esca ing to the sides of the condenser units an also prevent any rattling due tovibration of the motor. There are dead air spaces 26 at the right and left bf the condenser. These give to the condenser housing suflicient width to form a base for the various parts .of the machine. They also provide room for the bends 20 and 22 of the tubing. The radiating structure is applied only to the straight len hs of tubing which makes a very simple jo of it. Though, if other conditions permitted, the comp ete condenser could be made only as wide as the radiating structure shown and the latter would be provided with curved grooves to receive the bends of the tubing.

Where additional radiating surface is desirable, we may use three radiating structures as in Fi 7. The central structure 27 carries the tubing in its top and bottom faces as indicated at 19 and 21, such faces being about level with the centre of the tubing. And two additional and similar radiating structures 28 and 29 are applied to the top and bottom of the piping and soldered or brazed as described above. These outside or supplementary fins or radiating structures would ordinarily be of less depth than the central one.

The fins should be placed closer to ether (for refrigerators) than the ordinary s on radiators and similar structures, so that the rapidly moving column of air from the blower will be divided into sufliciently thin streams between the hot fins to take up a considerable quantity of heat in its brief time of passage through the condenser. The fins 14 therefore are comparatively short and close together. The limit in this respect must be such that the passage of air shall not be so impeded as to materially reduce the efficiency of the apparatus. The use of short fins close together is important also in cooling the liquid segregated near the discharge end of the tubing. The applying of the tube to both sides of a single radiating structure or set of fins gives at once the trapping arrangement described and also the desired proportion of tube surface to fin surface.

The addition of supplementary'radiating structures as in Fig. 7 would, however, be of advantage in some designs and uses of the heat exchanger. Preferably, the supplementary radiating structures 28 and 29 would be of about one-half the height of the central structure 27.

The tubing is preferably of copper, thou h this as well as the radiating structure may e made of other materials. The condenser of my improvement may be made to occupy only a fraction of the space taken by those commonly used in refrigerating machines and of the same efficiency. A saving of space is important in refrigerating apparatus. The compactness of the condenser and the shape which permits it to be used in place of the ordinary base are, therefore, ver advantageous. The double ended form 0 condenser illustrated is well adapted to the usual refrigerating machine in which the blower is at the center of the plate. But the principle may be applied to a machine having a single condenser unit with the air entering at one end and discharging at the other, or having any plurality of units arranged in various ways. The fin structure has an advantage of stiffness which enables it to carry the top plate of the housing and the machinery supported thereon in the manner of a series of supporting channels.

The tubing may be arranged in various other ways than those described. For example, instead of arranging it in two levels as shown, it may be arranged in any plurality of levels according to the total height required, and with any appropriate number of radiating structures arranged between the different levels of tubing and on top and bottom.

The heat exchanger is adapted also to various other uses; such for example as the heating of the air by circulating steam or other heating medium through the pipes or the cooling of the air by circulating cold brine through the pipes. Also the flow of the air through the exchanger may be by means of a blower as illustrated or by other positive means, or may be induced by setting the corrugated structure on edge with the air passages vertical to act in the manner of flues, as in certain radiators for heating the air in a room and circulating it.

In such flues, the shape of the corrugated sheet is of particular value. By having each pair of fins converging from the edges which are connected (by a plate 15) the complete corrugated'plate is of less width than if the fins were at a right angle to the pipe; without reducing the extent of radiating surface. Where two such plates are provided on opposite sides of a single pipe, or three such plates applied to two pipes as in Fig. 7, the reduction in total width is correspondingly greater. The acute angles made by each of the finswith the longitudinal plate also provide increased resistance to accidental deformation.

The same advantages can be secured by applying the corrugated plates illustrated to other heating elements; as by substituting for the tubing 19, elongated chambers or conduits of other shapes in cross" section, or electric heating elements of the so called strip type. The corrugated radiating structure may be made of plates extending integrally throughout its full length, or it may be made in a plurality of separate sections or pieces.

The invention may be utilized also in a single corrugated plate with a heating element extending along one side only thereof. And the corrugated plates may be united to the heating element in various mechanical wa s instead of the direct soldering and we ding above referred to.

In another application No. 433,529 filed March 6, 1930, I have described this and other heat interchangers of similar design and have claimed the same independently of the blower and other features of the refrigerating apparatus; the claims for the heat interchanger in the present case being specific to the interchanger of the other application and being restricted to the converging fin arran ement.

arious other modifications may be made by those skilled in the art without departing from the invention as defined in the following claims. 1 1. A refrigerating apparatus including in combination tubing through which the refrigerant is circulated, an air blower and a radiating structure applied to the tubing and forming channels for the air, the entrance ends of which channels are adjacent to the exit end of the tubing.

2. A refrigerating apparatus including tubing through which the refrigerant is circulated and a radiating structure applied to said tubing and arranged to form channels for the passage ofair, the tubing being at different levels so as to trap the condensed refrigerant and cool it while segregated from the gas.

3. A refrigerating apparatus including tubing through which the refrigerant is circulated and a radiating structure applied to said tubing and arranged to form channels for the passage of air, the tubing being at different levels with a lower portion interposed between two upper portions in the circuit thrjugh the tubing so as to trap the condensed Tefrigerant and cool it while segregated from the gas, and an air blower the outlet of which communicates with the said channels at end near which the condensed refrigerant is segregated.

4. A refrigerating apparatus including tubing through which the refrigerant is circulated and a radiating structure having a series of longitudinal fins forming channels for the passage of a cooling draft of air, the tubing being passed alternately across the upper and lower portions of the said radiating structure a plurality of times in the length of the tubing.

5. A refrigerating apparatus including tubing through which the refrigerant is circulated and a radiating structure applied to said tubing forming channels for the passage of a cooling draft of air, said tubing being located across the upper and lower portions of said radiating structure in a number of successive lengths of the tubing.

6. A heat interchanger including a blower and two heat interchanging units with a space between them for admission of air from said blower and with their opposite ends.

open for discharge of the air, the air passages of the respective units extending in opposite directions from thepoint of admission to the points of discharge.

7. A heat interchan er comprising a heating element and a radiating structure comprising transverse fins connected to each other in succession at alternate edges, each pair of fins converging from their connected edges toward the opposite side of the structure.

8. A heat interchanger including a \longitudinally extending tube and a radiating structure comprising a corrugated plate forming transverse fins connected to each other in succession at alternate edges, each pair of fins converging from their connected edges toward the opposite side of the plate, said structure having recesses extendin acgoss the corrugations and embracing sai tu e.

9. A heat interchanger comprising alongitudinal heating element and corrugated plates on opposite sides thereof with longitudinal recesses embracin the heating element, each of said plates orming transverse fins connected to each other in succession at alternate edges, each pair of fins converging from their connected edges toward the opposite side of the plate.

In witness whereof, I have hereunto signed my name.

GEORGE H. PHELPS.

CERTIFICATE OF CORRECTION.

Patent No. 1,846,608. Granted February 23, 1932, to

GEORGE H. PHELPS.

It is hereby certified that the assignee in the above numbered patent was erroneously described and Specified as "Metropolitan Engineering Corporation", whereas said assignee should have been described and specified as Metropolitan Engineering Company, as shown by the records of assignments in this office; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

' Signed and sealed this 22nd day of March, A. D. 1932.

M. J. Moore, (Seal) Acting Commissioner of Patents.

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