US3251409A - Condenser assembly - Google Patents

Description

y 7, 1966 R. M. HERBERT CONDENSER ASSEMBLY Filed Jan. 30, 1963 IN VEN TOR.

' constant pressure.

This invention relates generally to refrigeration and air-conditioning equipment and, more particularly, to improvements in air-cooled condensing devices for changing the state of a vaporized refrigerant to a liquid.

In a typical cooling system, a refrigerant, such as ammonia or certain of the Freon gases, is received from the evaporator as a superheated vapor by a compressor where it is raised to a relatively high pressure while at the same time adding-some additional heat of work to the already superheated gas. Thus the refrigerant vapor leaving the compressor contains appreciably more heat than is necessary at the pressure established by the compressor to remain in a stable gaseous state. The condenser in a cooling unit functions to bring about a change in state of the refrigerant from gaseous to liquid at an essentially This is accomplished by removing sufiicient heat from the refrigerant flowing through the condenser to cause condensate to form. To accomplish heat removal, it is known in the art to provide a tube and fin type condensor comprising one or more passes of heatconductive tubing through a transverse bank of serially spaced fins. In some residential and smaller commercial systems, it has been found most economical to use an air-cooled condenser to carry away the excess heat, thereby eliminating some of the more ponderous and expensive equipment required for water-cooled installations. Thus, a fan is conveniently provided which may be powered by the motor which drives the compressor, and which blows air over the condenser fins to extract heat from the refrigerant circulating through tubes.

The condenser unit must be of sufficient capacity to pen mit heat transfer adequate to reduce the temperature of the vaporized refrigerant flowing therethrough to the point Where condensation takes place. The capacity of a heat exchanger such as a condenser is proportional to the heat transfer area and, accordingly, the physical size thereof.- Because the amount of heat includes both the latent heat of vaporization and considerable superheat, condensers are often quite large. Accordingly, it is an object of the present invention to providean air-cooled condenser assembly which makes optimum use of available heat transfer capacity of the assembly by employing the radial as Well as axial components of air, moved by the cooling fan in effecting cooling of the vaporous refrigerant. Thus it is an object to make more efficient use of essentially the same basic components found in more conventional air-cooled refrigeration units or the like.

A further object of the invention is to provide an aircooled condenser assembly having means for precooling or reducing the amount of superheat present in the vapor discharged from the compressor prior to the entry of the vapor into the condenser without increasing the size or number of cooling fans or volume of cooling air moved otherwise required.

Another object of the present invention is to provide an improved air-cooled condenser assembly which has a reduced physical dimension made possible through more eflicient overall heat transfer, thereby effecting a space saving, in addition to an appreciable reduction in manufacturing cost.

Still another object of the present invention is to provide a quieter running assembly by baifiing otherwise objectionable fan'noise by means of heat transfer conduit United States Patent Patented May 17, 1966 peripherally disposed about the fan. These and other advantages of the present invention will become apparent from a reading of the following detailed description in conjunction with the appended drawings, wherein:

FIGURE 1 is a side elevation shown partially in section of a cooling unit constructed in accordance with the present invention;

FIG. 2 is a section of FIGURE 1 taken along line 22; and

FIG. 3 is a schematic representation of a cooling system constructed in accordance with the invention.

While the invention is susceptible of various modifications and alternative constructions, an illustrative embodiment is shown in the drawings and will be described below in considerable detail. It should be understood, however, that there is no intention to limit the invention to the specific form disclosed, but on the contrary, to cover all modifications, alternative constructions and equivalents falling within the spirit and scope of the invention as expressed in the appended claims.

Referring now, with particular attention, to the 31P- pended drawings wherein the invention is shown in one exemplary form, a portion of an exemplary residential cooling unit is indicated generally at 10, and is representative of residential or small commercial refrigeration or air-conditioning units having an improved condenser assembly, indicated generally at 11, integrated into the closed system.

FIGURE 3 of the drawings illustrates schematically a closed path system of the type here considered. Thus, the basic elements of the system comprise a compressor 15 which receives a low pressure superheated vaporized refrigerant, such as ammonia, through an input conduit 16 and mechanically raises the pressure of the vapor and also the temperature to some extent, by virtue of work performed on the vapor.

The hot vapor is then discharged from the compressor 15 through output conduit 17 which connects the compressor to the condenser assembly 11. In units of the size indicated, it is convenient to air cool the condenser rather than to employ water cooling, which requires more intricate and expensive equipment. Thus, the fan 19, having aerodynamically formed blades 20, is disposed adjacent the condenser assembly 11, and, for the purposes of the present invention, will be considered a part of it. The fan is powered by a motor M, which may also be conveniently employed to drive the compressor 15. It is the task of the condenser assembly to receive the hot vaporized refrigerant and remove the superheat and latent heat of vaporization therefrom in order to condense the same into a liquid while sustaining essentially the same pressure developed at the compressor 15.

Thus, refrigerant discharged from the condenser assembly 11 through conduit 22 is in a liquid state and at essentially the same pressure as the refrigerant discharged from the compressor 15. For the purpose of removing moisture formed in the liquid refrigerant, a liquid line giiygr 24a is interposed in the conduit 22, as shown in An expansion device 24 (FIG. 3) is provided downstream of the condenser assembly 11 and may be of any convenient form well known in the art. For example, a thermostatically controlled throttling valve may be employed for controlling the rate of flow through the expansion device. The expansion device is adapted to provide a drop in'pressure without loss of heat. While expansion, is at a relatively low pressure, and one at which the refrigerant will boil, or vaporize, at ambient condition. Such vaporization takes place in an evaporator 27, connected to the line 25. It is the function of the evaporator to expose the low pressure liquid refrigerant to a heat transfer area which is exposed, in the usual case to a flow of relatively warm air. The refrigerant absorbs heat from the ambient air about the evaporator thereby cooling down the ambient air. The absorbed heat causes the low pressure refrigerant to boil or vaporize, and usually to obtain a few degrees of superheat, i.e., an amount of heat over and above that which is required forthe refrigerant to reach a stable vapor state. It is desirable that a few degrees of superheat be obtained so as to minimize and eliminate, if possible, any particles of liquid remaining in the refrigerant as it passes from the evaporator to the input 16 of the compressor 15. It will be appreciated that particles of liquid refrigerant suspended in the low pressure vapor will adversely affect the performance of the compressor.

In accordance with the invention, the cooling unit is provided with an improved condenser assembly 11, which permits more eflicient use of heat transfer space available in the cooling unit. As previously noted, in prior condenser assemblies, it has been well known in the art to place a cooling fan adjacent a suitable tube and fin type condenser. Such an arrangement is indicated in FIGURES 1 and 2 at 31, wherein the fins 32 are supplied with refrigerant carrying conduit 33 arranged in parallel passes joined at their respective ends to adjacent passes by U shaped end connectors 34. The fan 19 is disposed adjacent the condenser 31, and is adapted to draw air through the condenser as indicated by the arrow A so that the axial components of the air being moved by the blades 20 of the fans as they revolve are directed over and through the bank of fins and associated conduit in a direction transverse to the face of the condenser. The air drawn through the condenser 31 is ambient air which is at a significantly lower temperature than the temperature of the liquid entering the condenser, and by virtue of the temperature gradient established, the air absorbs heat from the fins. As previously indicated, the condenser must have sufficient transfer area to dissipate the superheat contained in the refrigerant as well as the latent heat of vaporization, during the time the refrigerant is present in the condsenser, which is determined by the rate of flow of the refrigerant. The flow rate will be considered from the standpoint of economy and efiiciency viewing the installation as a whole.

In one of its aspects, the invention contemplates making use of available but otherwise unused radial components R of the air discharged by the revolving fan blades 20 to reduce the amount of superheat contained in the refrigerant prior to its being received in the condenser and thereby lessening the demand on the condenser, thus permitting a more eflicient operating cooling unit, as well as a reduction in physical dimension of the condenser 31. Thus, a helical coil of conduit 35 is provided about the periphery of the fan 19. In many cases the provision of such a coil involves lengthening the line between the compressor and condenser which would otherwise be required, and forming it in the manner indicated. The number of convolutions of conduit may vary in practice, depending upon the amount of precooling desired and the space available.

The coils are so positioned as to take maximum advantage of the radial components of air discharged from the fan blades 20. hus the exact location of the coil relative to the tips of the fan blades 20 will be determined by the aerodynamic design of the blade. In the present instance, for example, the radial component of air leaving the fan blade will have its optimum force at a slight rearward angle to the plane of the fan, and, accordingly, the coil shown in FIG. 1 is disposed rearwardly of the actual control plane of the fan blades 20, as seen in FIG. l,in position to receive the optimum radial flow of air from the fan as indicated by the arrow R. Variation in the coil position may be made without departure from the invention.

In keeping with the present invention, as the refrigerant vapor is discharged from the compressor, it will pass through the coil 35 about the periphery of the fan blades 20 where the radial components of the air will pass over and through the tubes. The convolutions of the coil are spread or spaced from one another a suflicient amount to permit maximum area of contact between tube and air, thereby removing as much of the superheat as possible transferred to the surface of the tubes from the hot refrigerant passing therethrough. The heated air is moved outwardly and away from the system.

Efficient heat transfer is maintained both in the condenser 31 and coil 35 by drawing cooling air through the condenser, in the mariner indicated. Thus, ambient air passes through the condenser 31 where it absorbs heat, which results in a rise in air temperature. The radial components of the air are discharged from the fan at this increased temperature, but because the vapor in the coil 35 is also warmer than that in the condenser, a suitable temperature gradient is provided between the coil and cooling air, thus permitting eflicient heat transfer. The temperature of the refrigerant is thereby reduced and at least a portion of the superheat removed without requiring a larger fan, or more than one fan, the reduction being accomplished by making use of available, but heretofore unused, components of air from the fan 19 and space about the fan which is otherwise present but unused.

Thus, the refrigerant vapor entering the condenser is already precooled, and at a lower temperature than would otherwise be expected, which means that the amount of heat that the condenser must remove is less and, therefore, a reduction in size of the condenser is possible. In order to attain the same performance from :a conventional condenser assembly, it would be necessary to decrease the refrigerant flow or increase, by some outside means, the volume of air passing over the condenser to increase the amount of heat removed. It will now be apparent to those skilled in the art that the net cooling effect of the present improved unit 10 is increased because the refrigerant is at a lower temperature, and thus capable of absorbing more heat from the warm air passing through the evaporator.

As a result of the present structure, the entire condenser assembly is more efficient than that employed in conventional units, which do not make full and optimum use of the cooling media, such as air, available to the unit.

I claim as my invention:

1. In an air-cooled condenser assembly adapted to be integrated with a cooling unit between a compressor and expansion device, said condenser assembly comprising the combination of a tube and fin type condenser, a cooling fan disposed opposite said condenser in a position such that said fan draws air through said condenser, a helical coil of heat transfer tubing peripherally disposed about said fan, spaced axially from the plane of said fan and in the path of the radial components of air moved by said fan, said helical coil being adapted to receive a superheated fiuid and effect heat transfer between said fluid and said radial components and thereafter pass said precooled fluid to said condenser where the same is condensed, the air flow caused by said fan being such that the temperature gradient between the air and the condenser is relatively the same as the temperature gradient between the radial air passing through said helical coil.

2. An air-cooled condenser assembly adapted to receive superheated fluid from a fluid source and reduce the same to a liquid the combination comprising a cooling fan having a plurality of blades, means for rotating the fan, a bank of finned condenser tubing located adjacent said fan on the inlet side thereof for the extraction of heat by the axial flow of air through the fan, and a length of condenser tubing interposed between said bank and said source so that said superheated fluid passes through said tubing to said bank, and said tubing being wound in a helix so as to form a plurality of spaced convolutions positioned with respect to the blades of the fan so that the air radially discharged from said blades passes between said convolutions for carrying away at least a portion of the superheat of said fluid between said source and said banks.

3. In combination with an air-cooled condenser for removing heat from a superheated fluid, a fan disposed adjacent said condenser in such position that the axial components of the air moved by said fan pass through said condenser, and means defining a conduit of high heat conductivity disposed about the periphery of said fan, and in the path of the peripheral components of the air moved by said fan, said conduit being joined with the inlet side of said condenser, so that said superheated fluid passes through said conduit to permit the transfer of heat therefrom to the air flowing past said peripherally disposed conduit, and thereafter said cooled fluid passes to said condenser for further cooling thereof.

4. In a condenser assembly, the combination of condenser, a motor driven fan in proximity to said condenser and so positioned that the axial components of the air moved by said fan pass through said condenser and conduit in the form of a coil disposed in spiral fashion about the periphery of thefan so that the peripheral components of the air moved by said fan pass over said conduit and through said coil, thereby effecting a first cooling stage of a vaporized superheated refrigerant passing therethrough, said coil being connected to the input side of said condenser, whereby said precooled vapor is passed to said condenser for further cooling the same to a liquid state.

5. In an air-cooled condenser assembly adapted to be integrated with a cooling unit between a compressor and an expansion device for condensing refrigerant vapor discharged from the compressor, the combination of a tube and fin type condenser, a cooling fan disposed adjacent said condenser such that the axial components of air moved by said fan are drawn between said fins, and means interposed in the line of discharge from the compressor to said condenser for precooling the refrigerant from the compressor, said precooling means being disposed about the periphery of said fan, whereby the radial components of the air moved by said fan pass over and about said means for removing heat therefrom.

6. An air-cooled condenser assembly adapted to condense a superheated fluid comprising the combination of a cooling fan, a finned condenser disposed opposite said fan and in the path of the axial component of air moved by said fan, a helical coil of heat transfer tubing disposed about the periphery of the fan and axially spaced therefrom such that the radial components of air moved by said fan pass over and through said tubing, said coils adapted to receive fluid in a superheated state and transfer heat therefrom to the radial components of the air moved by said fan thereby precooling said superheated fluid prior to its entry into said finned condenser and said precooled fluid being condensed in said finned condenser.

References Cited by the Examiner UNITED STATES PATENTS 1,582,192 4/ 1926 Stridell 62-507 1,598,048 8/ 1926 Burmeister -144 1,691,180 11/1928 Carrey 165125 1,896,080 2/1933 Hampsen 624-507 FREDERICK L. MA'ITESON, 111., Primary Examiner.

CHARLES SUKALO, Assistant Examiner.

Claims (1)

1. IN AN AIR-COOLED CONDENSER ASSEMBLY ADAPTED TO BE INTEGRATED WITH A COOLING UNIT BETWEEN A COMPRESSOR AND EXPANSION DEVICE, SAID CONDENSER ASSEMBLY COMPRISING THE COMBINATION OF A TUBE AND FIN TYPE CONDENSER, A COOLING FAN DISPOSED OPPOSITE SAID CONDENSER IN A POSITION SUCH THAT SAID FAN DRAWS AIR THROUGH SAID CONDENSER, A HELICAL COIL OF HEAT TRANSFER TUBING PERIPHERALLY DISPOSED ABOUT SAID FAN, SPACED AXIALLY FROM THE PLANE OF SAID FAN AND IN THE PATH OF THE RADIAL COMPONENTS OF AIR MOVED BY SAID FAN, SAID HELICAL COIL BEING ADAPTED TO RECEIVE A SUPERHEATED FLUID AND EFFECT HEAT TRANSFER BETWEEN SAID FLUID AND SAID RADIAL COMPONENTS AND THEREAFTER PASS SAID PRECOOLED FLUID TO SAID CONDENSER WHERE THE SAME IS CONDENSED, THE AIR FLOW CAUSED BY SAID FAN BEING SUCH THAT THE TEMPERATURE GRADIENT BETWEEN THE AIR AND THE CONDENSER IS RELA-

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