SPLIT DISCHARGE LINE WITH INTEGRATED MUFFLER FOR A
COMPRESSOR
BACKGROUND
Typical refrigeration and air conditioning systems rely on vapor-compression cycles to transfer heat from one location to another for the purposes of cooling or heating an enclosed space. Such vapor-compression cycles comprise a compressor, a condenser, an expansion device and an evaporator connected to form a closed-loop circuit. Each component of the system is connected by a length of piping that conducts a working fluid, such as a refrigerant, through the circuit. The compressor controls the flow of the fluid through the circuit to adjust the amount of temperature control that takes place in the space. Compressors rely on mechanical means, such as twin screws, reciprocating pistons or scrolls, for drawing in the fluid from an intake line, compressing the fluid, and expelling the fluid to a discharge line at a higher pressure to push fluid through the system. Thus, compressors only perform work on one small portion of the total working fluid in the system at a time, the size of which depends on the capacity of each compressor.
In chiller systems, where the vapor-compression circuit is used to facilitate cooling to various spaces within a building, multiple, large capacity compressors are often used to provide sufficient volumetric flow of refrigerant through the system. One such large-capacity system comprises a stacked chiller system in which the condenser, evaporator and compressor are stacked vertically one on top of the other. Often, due to manufacturing tolerances and variations of assembly, each chiller system takes on slight variations in the distances between connection points for each component. In particular, difficulties may arise in assembling compressor discharge lines between the compressor and the condenser. Typical vapor-compression circuits include a single discharge line connecting the compressor with the condenser. The difficulties in assembling such discharge lines are exacerbated by the need to include other system components such as mufflers for damping discharge pulses, valves for servicing the chiller system, and other components. Usually, the working fluid is discharged from the compressor in pulses as each compressed portion of fluid is released from the mechanical compression means, thus producing a burst of wave energy that propagates throughout the vapor-compression system. The compression means are typically turned by motors operating at speeds such that the wave pulsations are discharged at a high frequency. The pulsations not only
produce vibration of the compressor, but also produce noise that is amplified by the working matter and the compressor. Such vibration is undesirable as it wears components of the compressor and produces additional noise as the compressor vibrates. The magnitude of the discharge pulsations is also intensified in large capacity compressor applications. Thus, compressors are typically fitted with mufflers downstream of the discharge pulses of the compressor to attenuate pulsations of the refrigerant.
Also, typical compressors include oil systems that circulate lubricating and cooling oil to the mechanical compression means within the compressor, where the oil and refrigerant become entrained. It is necessary to separate the oil from the refrigerant before the refrigerant enters the condenser to optimize heat exchange efficiency of the system. Thus, vapor-compression circuits are typically fitted with separators positioned between the compressor and the condenser to filter oil from the refrigerant.
Conventional vapor-compression system designs fail to address the various performance requirements of compressor discharge flow, muffler positioning and separator intake flow, in a compact, convenient and inexpensive package that also permits minute adjustments necessary to assemble such system and accommodate geometric tolerancing limitations and installation variations. There is, therefore, a need for an improved system for connecting compressors with condensers in vapor- compression systems.
SUMMARY
The present invention is directed to a discharge pipe for connecting a compressor with a condenser in a vapor-compression system. The discharge pipe includes an intake segment, a muffler, a splitter segment and first and second discharge segments. The intake segment is configured to connect to a discharge port of the compressor and receive compressed refrigerant flow. The muffler is connected to the intake segment for attenuating pulsations within the compressed refrigerant flow. The splitter segment is connected to the muffler and configured to divide the compressed refrigerant flow into first and second branches. The first discharge segment connects to the splitter to receive the first branch and is configured to connect to the condenser at a first position. The second discharge segment connects to the splitter to receive the second branch and is configured to connect to the condenser at a second location.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram of a vapor-compression system including a split discharge line having an integrated muffler in accordance with one embodiment of the present invention. FIG. 2 is a side elevational view of a stacked chiller system including a split discharge line as shown in FIG. 1.
FIG. 3 is a perspective view of another embodiment of a split discharge line in accordance with the present invention also including an integrated muffler and flow control valves. DETAILED DESCRIPTION
FIG. 1 shows a schematic of vapor-compression system 10 including split discharge line 12A, integrated muffler 14 and integrated valves 15A and 15B. Vapor- compression system 10 includes compressor 16, condenser 18, expansion device 20 and evaporator 22. Compressor 16, condenser 18, expansion device 20 and evaporator 22 are connected in a series circuit using conduit including compressor discharge piping 12 A, compressor suction piping 12B, condenser piping 12C and evaporator piping 12D. Vapor-compression system 10 also includes other components such as economizer 24 and oil distribution system 26. In one embodiment, vapor-compression system 10 comprises a water cooled "chiller" system that is used to provide cooled air to a plurality of spaces such as within a building. For example, evaporator 22 also includes manifolds 28A and 28B that conduct a coolant, such as water or a refrigerant, from a "cooler" heat exchanger through evaporator 22. The cooler heat exchanger services one or more heat exchangers used to cool the plurality of spaces. Condenser 18 includes manifolds 29A and 29B that circulate water from a cooling tower through condenser 18. The cooling tower cools water that is used to transfer heat from the chiller system.
In the embodiment shown, compressor 16 is a rotary screw compressor that compresses a refrigerant, such as R- 122, to provide heated, high pressure refrigerant to condenser 18 through discharge line 12 A. In other embodiments, compressor 16 includes other mechanical means for compressing a working fluid, such as reciprocating pistons or orbiting scrolls. For any mechanical compression means, compressor 16 is provided with a source of oil from oil distribution system 26 to provide cooling and lubrication to compressor 16. The oil is mixed with the refrigerant within compressor 16 and both are delivered to condenser 18 through discharge line 12 A. Discharge line 12A includes muffler 14 for attenuating pulsations and vibration resulting from a pulsed
discharge of the refrigerant from compressor 16. The oil is filtered from the refrigerant within condenser 18 through oil separator 30 that collects and returns the oil to compressor 16 via distribution system 26. Using cooling water from the cooling tower provided through manifold 29B, the refrigerant cools and condenses to a saturated liquid having a slightly lower temperature at a high pressure within condenser 16, and rejecting heat to the water-based heat exchanger.
From condenser 18, the refrigerant is conducted through condenser piping 12C to expansion device 20 whereby the refrigerant undergoes a flash evaporation process to lower the pressure and temperature and is converted to two-phase refrigerant comprising gaseous and liquid phase refrigerant. Under pressure from compressor 16, the refrigerant continues through evaporator piping 12D to evaporator 22 whereby the relative warmth of the coolant from the cooler heat exchange provided by manifold 28B vaporizes the refrigerant into a saturated vapor phase refrigerant. Under suction from compressor 16, the refrigerant returns to compressor 16. As such, vapor-compression system 10 operates using well-known thermodynamic principles to transfer heat from evaporator 22 to condenser 18.
For clarity, FIG. 1 schematically diagrams the assembly of vapor-compression system 10. In practice, it is desirable to assemble system 10 compactly such that system 10 can be positioned within smaller spaces inside of, or close to, a building or some other confined place. As such, it becomes a design consideration in positioning and assembling the components of system 10, such as compressor 16, condenser 18 and evaporator 22. Compressor discharge line 12A of the present invention facilitates assembly of system 10 by providing compact and flexible piping for connecting compressor 16 to condenser 18, incorporating muffler 14 and service valves 15A and 15B in an easily assembled and easily manufactured system.
FIG. 2 shows split discharge line 12A having integrated muffler 14 and integrated valves 15A and 15B incorporated into a stacked chiller system. The stacked chiller system includes compressor 16, condenser 18, expansion device 20 and evaporator 22, which are connected to form vapor-compression system 10 as shown schematically in FIG. 1. Although FIG. 2 shows a single compressor chiller system, other embodiments of the invention may be incorporated into double or multiple compressor chiller systems. Refrigerant discharged from compressor 16 travels through discharge piping 12A to condenser 18, through expansion device 20 to evaporator 22, and back to compressor 16 through compressor suction piping 12B. Additionally, as indicated by arrows, another
fluid, such as water from a cooling tower, is circulated through condenser 18 to cool the refrigerant before the refrigerant is passed to expander 20. Likewise, as indicated by arrows, a coolant, such as a refrigerant from a cooler heat exchanger, is circulated through evaporator 22 to dump heat into the refrigerant before the refrigerant is passed back to compressor 16. The stacked chiller system also includes oil distribution system 26 which returns oil separated from the compressed refrigerant by separator 30 within condenser 18 to compressor 16 whereby it is used to lubricate the mechanical compression system within compressor 16.
Condenser 18 comprises a shell and tube heat exchanger in which shell 31 is partially cut away in FIG. 2 to show tube bundle 32 and oil separator 30. Evaporator 22 also comprises a shell and tube heat exchanger including shell 33. Oil separator 30 comprises a filtration system in which incoming refrigerant/oil mixture is collected at distal ends of separator 30 from the various branches of discharge line 12A and directed toward the center or middle portion of separator 30 whereby the mixture is passed through one or more separation medium screens. The screens have porosity large enough to permit refrigerant to pass through, but small enough to prevent oil from passing through. The separated refrigerant flows down from separator 30 to interact with tube bundle 32, while the separated oil is collected by oil distribution system 26. In other embodiments, separator 30 operates with other types of filtration systems. Various configurations of the stacked chiller system have capacities such that they are suitable for cooling large buildings or spaces. As such, the individual components of the vapor-compression system are large in size and heavy such that assembly varies slightly from one system to the next. In one embodiment of chiller system 10 in which the present invention is used, evaporator 22, condenser 18 and compressor 16 are stacked in a vertical configuration such that one rests on top of the other using various hardware. In one embodiment, condenser 18 and evaporator 22 are stacked on top of each other using brackets 34A and 34B. Brackets 34A and 34B include footings 35 A and 35B to provide a foundation upon which the chiller system rests. Footings 35 A and 35B are typically welded to a floor, or some other anchor point, such that the chiller system is immobilized once installed. Brackets 34A and 34B are welded to end caps of manifolds 28A, 28B, 29A and 29B to support evaporator 22 rigidly above condenser 18. Compressor 16 is connected to evaporator 22 using various means such as welded and fastened brackets such that compressor 16 is supported above evaporator 22. After condenser 18, evaporator 22 and compressor 18 are assembled, the
various piping systems for the chiller system are installed, such as used in economizer 24 and oil distribution system 26. Also, compressor inlet line 12B and compressor discharge line 12A are installed to connect compressor 16 with condenser 18 and evaporator 22. In other configurations, chiller systems are installed in side-by-side systems in which condenser 18 and evaporator 22 both rest on footings that support the system. Such side-by-side configurations are also assembled using brackets that join condenser 18 and evaporator 22. The various embodiments of discharge line 12A described herein are suitable for use with such side-by-side chiller configurations.
As such, various tolerance limits are accumulated as condenser 18, evaporator 22 and compressor 16 are assembled, and the exact three-dimensional relationship between these components varies from one chiller system to another. For example, the welding process used to fasten footings 35 A and 35B and brackets 34A and 34B produce slight variations in the position of condenser 18 and evaporator 22. Furthermore, the exact position of various features of each component varies within the acceptable tolerance range for each component. In particular, the position of discharge port 36 of compressor 16 and inlet ports 37 A and 37B of condenser 18 are located within a tolerance band as defined by the final design specifications. Thus, due to various manufacturing and assembly factors, the three-dimensional vectors between discharge port 36 and inlet port 37A, discharge port 36 and inlet port 37B, and inlet port 37A and inlet port 37B vary from installation to installation.
Overcoming the variations in these vectors and other benefits are achieved with the configuration and assembly of split discharge line 12A of the present invention. Discharge pipe 12A also allows for integrating other components into the chiller system, such as muffler 14 and valves 15A and 15B, in a compact manner. Typically, discharge line 12A extends from condenser 18, to alongside evaporator 22 and up to compressor 16. In various embodiments of the invention, discharge line 12A includes various bends such that discharge pipe 12A bends around evaporator 22 to reach the inlet ports of condenser 18 and the discharge port of compressor 16. For example, in one embodiment, discharge pipe 12 A includes a thirty degree bend to extend from alongside evaporator 22 to inlet ports 37 A and 37B, which, in various embodiments, are positioned thirty degree from top-dead-center of condenser 18. Discharge pipe 12A also provides the added benefit of improving refrigerant flow into oil separator 30. Specifically, discharge line 12A slows the velocity of the refrigerant as it enters separator 30 such that the separation medium screens are better able to filter oil from the refrigerant. As such,
discharge pipe 12A provides a compact, efficient and easily manufacturable system for conveying refrigerant from compressor 16 to condenser 18.
FIG. 3 shows split discharge line 12A having integrated muffler 14 and integrated flow control valves 15A and 15B. Discharge line 12A also includes inlet elbow 38, T- joint 39, first split line 4OA, second split line 4OB, first split elbow 42 A, second split elbow 42B, first outlet line 44 A and second outlet line 44B.
Inlet elbow 36 is connected to discharge port 36 of compressor 16 with flange 46, which is typically bolted to compressor 16. In one embodiment, inlet elbow 38 is fabricated from steel tubing such that elbow 38 is rigidly connected with compressor 16 to provide a stable platform for connecting with muffler 14. In various embodiments of the invention, inlet elbow 38 has a large diameter compatible with the discharge ports of high capacity compressors suitable for use in water cooled chiller systems. In various high-capacity embodiments of the invention, elbow 38 has a diameter of 5 inches (—12.7 cm) or 6 inches (-15.24 cm). Inlet elbow 38 includes a ninety-degree bend and is oriented to direct compressed refrigerant flow perpendicular to the direction of refrigerant flow within condenser 18. Inlet elbow 38 extends the flow of compressed refrigerant from discharge port 36 laterally from compressor 16 such that the flow of the compressed refrigerant is extended to the side of compressor 16 above evaporator 22 and condenser 18. Muffler 14 is connected to the outlet end of elbow 38 and includes an inner flow path compatible for connecting with elbow 38. Muffler 14 comprises any suitable muffler as is used in the industry and is configured to efficiently attenuate pulsation transmission in the pulsed discharges of the compressed refrigerant. In various embodiments, muffler 14 comprises a baffle type or sound absorbing type muffler, such as a baffle tube or fiberglass disk style muffler. As depicted in FIG. 3, muffler 14 includes eyelets or hooks which are used to facilitate installation of split discharge line 12A with a crane or some other lifting device.
T-joint 39 is fluidly connected to the outlet end of muffler 14 and includes inlet elbow 39A, splitter 39B and discharge portions 39C and 39D. In other embodiments, the muffler may be disposed in other configurations such as to eliminate the need for an inlet elbow 39A. In one embodiment, T-joint 39 is comprised of steel such as that of elbow 38. Typically, inlet elbow 39A has a diameter matching that of inlet elbow 38 and the inner flow path of muffler 14 to minimize pressure loss in the flow of the compressed refrigerant, which increases efficiency of vapor-compression system 10. As such, a
continuous, generally constant cross section flow path is formed by elbow 38, muffler 14 and inlet elbow 39 A. In the embodiment of FIG. 3, inlet elbow 39A includes a ninety- degree bend and directs the flow of compressed refrigerant parallel to the direction of refrigerant flow through condenser 18. As shown in FIGS. 2 and 3, inlet elbow 39A is oriented with an outlet end thereof directed towards the condenser 22 to extend the flow of compressed refrigerant down from compressor 16 to alongside condenser 22. Inlet elbow 39A leads into and is in fluid communication with an inlet of the "T" or splitter 39B.
Splitter 39B comprises a segment of tubing integral with elbow 39A that is oriented generally perpendicular to the discharge end of inlet elbow 39A. Splitter 39B produces a two-way, ninety-degree redirection in the flow of compressed refrigerant such that the refrigerant is again flowing perpendicular to flow of refrigerant within condenser 18. The middle portion of splitter 39B has a diameter matching that of elbow 38 and elbow 39A to minimize pressure loss in the flow of compressed refrigerant. The distal ends of splitter 39B are tapered, or necked down, to a diameter smaller than that of inlet elbow 38 and inlet elbow 39A to form discharge portions 39C and 39D. The diameters of discharge portions 39C and 39D are typically sized to match that of a diameter in which standard tubing is available in accordance with the desired balance of pressure drop for the system 10. For example, copper tubing is typically available in 3.125 inch (~ 7.94 cm) diameter stock tubing.
First split line 4OA and second split line 4OB are connected to discharge portions 39C and 39D, of splitter 39B respectively. In one embodiment, split lines 4OA and 4OB are comprised of stock copper tubing segments sized to be received into discharge portions 39C and 39D, respectively. Split lines 4OA and 4OB extend generally horizontally to direct the flow of the compressed refrigerants out toward inlet ports 37A and 37B of condenser 18. Split line 4OA connects with valve 15A at its distal end. Likewise, split line 4OB connects with valve 15B at its distal end. In one embodiment of the invention, valves 15A and 15B comprise stock ball valves as are commercially available. Valves 15A and 15B provide a means for isolating components of the chiller system in order to perform service or maintenance. For example, valves 15A and 15B can be shut to allow the separation medium screens within separator 30 to be cleaned or replaced.
Elbows 42A and 42B connect with valves 15A and 15B, respectively. In the illustrated embodiment, elbows 42A and 42B include ninety degree bends that redirect
the flow of the compressed refrigerant such that the compressed refrigerant is flowing parallel to the direction of refrigerant flow within condenser 18. Outlet lines 44A and 44B connect to elbows 42A and 42B, respectively, to extend the flow of compressed refrigerant from discharge port 36 of compressor 16 to inlet ports 37A and 37B, respectively, of condenser 18. Outlet lines 44A and 44B can include slight bends such that outlet lines wrap around the curve of shell 33 of evaporator 22 to enter inlet ports 37A and 37B. As shown in the embodiment of FIGS. 2 and 3 embodiment, top portions of outlet lines 44A and 44B slope slightly away from evaporator 22, while bottom portions of outlet lines 44A and 44B slope slightly toward evaporator 22 with respect to the downward flow of the compressed refrigerant. In one embodiment of the invention, outlet lines 44A and 44B include thirty degree bends, but other angles of bends may used in other embodiments to accommodate extension from discharge port 36 to inlet ports 37 A and 37B, depending on, for example, the specific compressor used. Such bends may be in the range of approximately ten to approximately fifty degrees. As such, split discharge line 12A remains closely situated near compressor 16, evaporator 22 and condenser 18 such the overall width of the chiller system is not expanded and remains in a compact configuration. Outlet lines 44A and 44B are manufactured from stock sized copper tubing having a diameter matching that of split lines 4OA and 4OB.
The outlet ends of outlet lines 44A and 44B extend far enough to complete the connection of discharge port 36 with inlet ports 37A and 37B, extending into shell 31 of condenser 18 to join with oil separator 28. In other embodiments of the invention, valves 15A and 15B can be positioned at the discharge ends of outlet lines 44A and 44B, whereby connection to inlet ports 37A and 37B can be completed with additional segments of piping. Split line 4OA, valve 15 A, elbow 42A and outlet line 44A extend from discharge port 36 to inlet port 37A. Likewise, split line 4OB valve 15B, elbow 42B and outlet line 44B extend from discharge port 36 to inlet port 37B. As such, split discharge line 12A provides a system for connecting discharge port 36 with inlet ports 37A and 37B, while providing a platform for muffler 14 and valves 15A and 15B, which accommodates manufacturing and assembly variations in stacked chiller systems. Specifically, the various connection points and material properties, among other things, allow split discharge line 12A to accommodate variations in geometric tolerance limits within the chiller system.
As discussed above, the three-dimensional vectors between discharge port 36 and inlet ports 37A and 37B change after a chiller system is assembled. The individual
tolerances for each components, such as brackets 34A and 35 A, combine with variations that arise during assembly, such as welding of footings 35 A and 35B, to change the distance between these openings, requiring split discharge line 12A to have variability in assembly and installation. For example, if split discharge line 12A were comprised of a single, steel discharge pipe, it would be difficult or impossible to connect vertical portions 44A and 44B with inlet ports 37A and 37B if the position of discharge port 36, with respect to inlet ports 37 A and 37B, were out of spec due to accumulation of tolerances or assembly variations. Thus, in the present invention, the split discharge pipe is divided into smaller segments such that accumulated tolerances or assembly variations can be accommodated by discharge line 12A. The present invention, however, also strategically divides discharge line 12A so that other system components, such as muffler 14 and valves 15A and 15B, can be incorporated into discharge line 12A in a compact manner.
In one embodiment, elbow 38 and T-joint 39 are comprised of steel such that they are rigidly connected with compressor 16 and muffler 14. In one embodiment of the invention, split lines 4OA and 4OB and outlet lines 44A and 44B are manufactured of stock sized copper tubing. Copper is more easily bent than steel such that the distal ends of outlet lines 44 A and 44B can be slightly adjusted for insertion into inlets 37A and 37B without producing excessive stress on outlet lines 44 A and 44B. Furthermore, the distal ends of outlet lines 44A and 44B can be adjusted by rotating the various tube components at their juncture points with adjoining components. For example, T-joint 39 can be rotated in muffler 14 to raise and lower split lines 4OA and 40B with respect to condenser 18, and split lines 4OA and 4OB can be rotated in discharge portions 39C and 39D of T-joint 39 to adjust the horizontal positions of vertical lines 44A and 44B with respect to condenser 18. Additionally, elbows 42 A and 42B and discharge lines 4OA and 4OB provide an additional means for individually adjusting the position of outlet lines 44A and 44B. In other embodiments, elbow 38 can be rotated in muffler 14 to accommodate design and assembly variations. For example, elbow 38 can be rotated to direct refrigerant flow in a direction parallel to the direction elbow 39A of T-joint 39 directs flow, such as for use in side-by-side chiller system configurations of split discharge line 12 A. After split discharge line 12A is installed into a chiller system, the individual joints can be brazed together to lock discharge line 12A in place. Alternatively, other types of fastening means can be utilized. Inlet elbow 39 of T-joint 39 includes vent 48 such that gas can be injected into discharge line 12A during the
brazing process, and gas can be vented out of discharge line 12A after the brazing process, during operation of the chiller, or during service or maintenance operations. Vent 48 comprises any valve as is known in the art.
Thus, split discharge line 12A of the present invention is easily manufactured and assembled and provides for the easy assembly of a chiller system. In particular, the split discharge line accommodates assembly variations in installed chiller systems that arise due to assembly variances or tolerance accumulation. For example, the split discharge line includes components that are formed from stock hardware such that the discharge line is readily customizable. The split discharge line includes various assembly points such that the configuration thereof is readily adjustable. The split discharge line also incorporates other system components, such as mufflers and valves, in a compact manner. Additionally, the split discharge line accommodates oil separators having dual inlet openings and regulates refrigerant flow to improve oil separation. In other embodiments of the invention, the diameters and lengths of the various tubing are sized to assist in attenuating pulsations in the compressed refrigerant discharged from compressor 16. For example, the lengths and diameters of split lines 4OA and 4OB and outlet lines 44A and 44B can be selected based on the magnitude of the wavelengths of the pulsations in the refrigerant to attenuate such pulsations, as is known in the art. The split discharge line also minimizes pressure loss between a compressor and condenser in a vapor-compression system.
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.