The present invention in general relates to an integrated or internal oil separator for heating, ventilation, and air conditioning (referred hereinafter as "HVAC") system. More particularly, the invention relates to an apparatus and method for separation of oil and refrigerant using a circumferential flow oil separator.
BACKGROUND OF THE INVENTION
Refrigeration systems use vapor compression refrigeration cycle that include chillers. A refrigeration cycle comprises four main processes i.e., compression, condensation, expansion, and evaporation. Oil is mixed with refrigerant in compressor that is used for lubricating, cooling, sealing, silencing (reducing pressure pulsation) and for auxiliary functions. However, oil needs to be separated from the refrigerant and oil mixture to enhance the efficiency and reliability of the refrigeration system as the refrigerant undergoes a phase change.
Fig. 1 represents a refrigeration cycle 100 comprising a compressor 102, a condenser 104, an expansion valve 106 and an evaporator 108 for executing the refrigeration cycle. Conventionally, for separation of the refrigerant and oil mixture in the refrigeration cycle, an oil separator 118 is installed on the compressor discharge line before the condenser 104. The oil separator is a pressure vessel having a discharge gas (refrigerant and oil mixture) inlet connection, a refrigerant gas outlet connection, and at least one oil outlet connection. The separated refrigerant is supplied to the condenser 104 and the oil is separated and returned to the compressor 102.
Conventional oil separators generally have a single inlet through which the refrigerant gas and oil mixture enters the oil separator and strikes on the walls of the oil separator. Large and heavy particles of the oil from the refrigerant and oil mixture settle down and the small and lighter particles move towards the mesh. The refrigerant and oil mixture need sufficient time to travel for oil particles to settle by gravity. This requires either too long gravity separation region or very large

diameter oil separator to reduce the refrigerant and oil mixture velocity. This, however, would incur additional cost.
Another possible option is to place an oil separator inside a condenser shell called as 'internal oil separator' for refrigerant condenser. This allows for a very light material (i.e., sheet metal) to be used for the oil separator because the oil separator becomes a non-pressure part having pressure difference of only 1-2 psi across it. However, this configuration requires a large diameter condenser shell to accommodate the internal oil separator's cross section area. The cross-section area is required to reduce velocity of refrigerant and oil mixture in the internal oil separator. This cross-section area depends upon the condenser shell diameter and oil separator height in axial flow of the refrigerant and oil mixture. Splitting axial flow in two halves reduces height to an extent but there is a limit to which cross-section area can be increased without increasing height and diameter, as the condenser shell length is parallel to flow of the refrigerant and oil mixture and not perpendicular to it.
In view of the afore-mentioned problems, there is a need of an efficient, compact, and cost-effective design for oil separator in the refrigeration system.
SUMMARY OF THE INVENTION
Various embodiments of the invention describe an apparatus for heating, ventilation, and air conditioning (HVAC) system. The apparatus comprises an inner shell extending along a length of an outer shell and at least one outer shell inlet which allows refrigerant and oil mixture to enter into the outer shell. The refrigerant and oil mixture impinges onto an outer wall of the inner shell and flows circumferentially between an inner wall of the outer shell and the outer wall of the inner shell. At least one mesh is arranged between the inner shell and the outer shell along the length of the outer shell to separate oil and refrigerant from the refrigerant and oil mixture. At least one inlet on inner shell allows the separated refrigerant to enter inside the inner shell for condensation.

In an embodiment of the invention, the refrigerant and oil mixture flows and splits to move in different directions circumferentially between the inner wall of the outer shell and the outer wall of the inner shell.
In an embodiment of the invention, at least one mesh is positioned longitudinally to receive the refrigerant and oil mixture from each direction.
In an embodiment of the invention, the at least one mesh comprises two or more meshes, wherein the at least one inner shell inlet is located on the inner shell and is positioned between the two meshes to transfer the separated refrigerant into the inner shell for condensation.
In yet another embodiment of the invention, the inner shell is concentric with the outer shell.
In another embodiment of the invention, the inner shell is eccentric with the outer shell.
In still another embodiment of the invention, the outer shell comprises at least one outlet to allow separated oil from the refrigerant and oil mixture to flow outside the outer shell and at least one outer shell inlet is located on the outer shell.
In still another embodiment of the invention, the apparatus comprises one or more baffles that are arranged in series on the inner wall of the outer shell and the outer wall of the inner shell.
In an embodiment of the invention, the apparatus comprises deflectors including plurality of intra-cut rings present at the point of impingement of the refrigerant and oil mixture on the outer wall of the inner shell to deflect the refrigerant and oil mixture.
In yet another embodiment of the invention, the deflectors deflect the refrigerant and oil mixture towards different directions.
In an embodiment of the invention, the inner shell and the outer shell are cylindrical in shape.

In a different embodiment of the invention, the oil is separated from the refrigerant and oil mixture by virtue of change in direction, gravity and further by filtration using the at least one mesh.
Various embodiments of the invention describe a method of separating oil and refrigerant from refrigerant and oil mixture. The method comprises allowing the refrigerant and oil mixture to enter into an outer shell through at least one outer shell inlet. The refrigerant and oil mixture impinges from the at least one outer shell inlet onto the outer wall of the inner shell. The refrigerant and oil mixture flows circumferentially between an inner wall of the outer shell and an outer wall of an inner shell. Oil and refrigerant are separated from the refrigerant and oil mixture using at least one mesh. The mesh is arranged between the inner shell and the outer shell along the length of the outer shell to allow the separated refrigerant to enter inside the inner shell using at least one inner shell inlet for condensation.
In another embodiment of the invention, the refrigerant and oil mixture flows and splits to move in different directions circumferentially between the inner wall of the outer shell and the outer wall of the inner shell.
In another embodiment of the invention, the mesh is positioned longitudinally to receive the refrigerant and oil mixture from each direction.
In another embodiment of the invention, the at least one mesh comprises two or more meshes, wherein the at least one inner shell inlet located on the inner shell is positioned between the two meshes to transfer the separated refrigerant to the inner shell for condensation.
In yet another embodiment of the invention, the outer shell comprises at least one outlet configured to allow separated oil from the refrigerant and oil mixture to flow outside the outer shell and at least one outer shell inlet located on the outer shell.
In an exemplary embodiment of the invention, one or more baffles arranged in a series on the inner wall of the outer shell and the outer wall of the inner shell.

In yet another embodiment of the invention, deflectors including a plurality of intra cut rings present at the point of impingement of the refrigerant and oil mixture on the outer wall of the inner shell to deflect the refrigerant and oil mixture.
In yet another embodiment of the invention, the oil is separated from the refrigerant and oil mixture by virtue of gravity and further by at least filtration by the one or more mesh.
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 depicts a refrigeration cycle generally used for refrigeration.
Fig. 2 depicts a chiller having an exemplary inner shell with - a circumferential flow oil separator according to an exemplary embodiment of the invention.
Fig. 3(a) depicts an exemplary longitudinal sectional view of inner shell with a circumferential flow integrated oil separator having inner shell as pressure part according to an exemplary embodiment of the invention.
Fig. 3(b) depicts an exemplary sectional side view of inner shell with a circumferential flow integrated oil separator having inner shell as pressure part according to an exemplary embodiment of the invention.
Fig. 4(a) depicts an exemplary longitudinal sectional view of inner shell with a circumferential flow integrated oil separator having inner shell as non-pressure part according to an exemplary embodiment of the invention.

Fig. 4(b) depicts an exemplary sectional side view of inner shell with a circumferential flow integrated oil separator having inner shell as non-pressure part according to an exemplary embodiment of the invention. Fig. 5 depicts an exemplary view of baffles in the circumferential flow integrated oil separator in accordance with an exemplary embodiment of the invention.
Fig. 6(a) and fig. 6(b) depict a front sectional view and side sectional view respectively of an exemplary design of inner shell with a circumferential flow integrated eccentric oil separator in accordance with an exemplary embodiment of the invention.
Fig. 7(a) and 7(b) depicts an exemplary front sectional view of an- inner shell with a circumferential flow integrated eccentric oil separator according to an exemplary embodiment of the invention.
Fig. 8 depicts an exemplary front sectional view of a U-type inner shell with a circumferential flow integrated oil separator according to an exemplary embodiment of the invention.
Fig. 9 depicts an exemplary front sectional view of the inner shell with a circumferential flow integrated oil separator with a breaker in between meshes according to an exemplary embodiment of the invention.
Fig. 10 depicts an exemplary flowchart illustrating a method to perform the invention according to an exemplary embodiment of the invention.
Fig. 11 depicts an exemplary flowchart illustrating a method of manufacturing an inner shell with a circumferential flow integrated oil separator according to an exemplary embodiment of the invention.
Fig. 12 depicts an exemplary flowchart illustrating a different method of manufacturing an inner shell with a circumferential flow integrated oil separator according to an exemplary embodiment of the invention.
Fig. 13 depicts an exemplary flowchart illustrating a different method of manufacturing an inner shell with a circumferential flow prefabricated internal oil separator according to an exemplary embodiment of the invention.

Corresponding reference numerals indicate corresponding parts throughout the drawings.
DETAILED DESCRIPTION OF THE INVENTION
Described herein is a technology for an integrated or internal oil separator having a circumferential flow of refrigerant and oil mixture. The oil separator may be assembled or integrated with the condenser of the refrigeration system. The oil separator is an apparatus for heating, ventilation, and air conditioning (HVAC) system comprising an inner shell extending along a length of an outer shell. At least one outer shell inlet is embedded on the outer shell to allow refrigerant and oil mixture to enter into the outer shell. The refrigerant and oil mixture impinges onto an outer wall of the inner shell and flows circumferentially between an inner wall of the outer shell and the outer wall of the inner shell. The apparatus comprises at least one mesh, arranged between the inner shell and the outer shell along the length of the outer shell, and configured to separate oil and refrigerant from the refrigerant and oil mixture. At least one inner shell inlet to allow the separated refrigerant to enter inside the inner shell for condensation.
The refrigerant and oil mixture from the compressor enters the oil separator through an inlet. It may be noted that the entry of the refrigerant and oil mixture (hereinafter "mixture") into the oil separator having the outer shell and the inner shell may be through one or more inlets (from same or different sides). The inner and outer shells may be spherical, cylindrical, curved or of any other shape. The inlets may be of different size and shape that control the inside flow distribution of mixture as well as a flow distribution index on the mesh inlet. Different combinations of diverted shapes or focused shapes inlet and/or outlet nozzles may be used for controlling the flow of mixture into the oil separator. The oil separator may also comprise components such as baffles, deflectors or any other similar components. Open ends of the shell may be closed using tube sheets at both ends. In the inner shell with a circumferential flow oil separator having inner (condenser) shell as pressure part, the tube sheets can be welded to inner shell. In the inner shell with a circumferential

flow oil separator having inner (condenser) shell as non-pressure part the tube sheets can be welded to outer shell. The tube sheets disclosed in the present invention may be plain, stepped, grooved or any other similar or different type. The side closing ring plates are welded to inner & outer shells on both the sides to close the open ends on both the sides. The side closing ring plates are used to confine the refrigerant & oil mixture in annular space formed between inner and outer shells and side closing ring plates.
As used herein, a plurality of embossed structures may be fixed on the walls on of the integrated oil separator. The embossed structures may be baffles restricting the circumferential flow of the mixture as the mixtures passes towards the mesh. The embossed structure may be similar or different in shape. For example, the deflectors may have plain, curved, perforated shapes and may be placed radially, tangentially or axially on the outer wall of inner shell. The outer shell may be made up of thick material as it is a pressure vessel. Whereas the inner shell may be of thick material, in case the inner shell is also a pressure part, or it may be made up of thin material, in case it is a non-pressure part.
As used herein, the inner wall of outer shell & outer wall of inner shell may be plain or made from checkered plate for easy oil draining. These surfaces may also be provided with screens for easy oil draining.
As used herein, the present invention is described taking an example of the integrated oil separator. However, the oil separator may also be an internal oil separator. The internal oil separator can be manufactured as separate item and then can be assembled together with condenser. However, the working principles are described herein are same and are applicable to the internal oil separator as well.
The outer wall of the inner shell may comprise a plurality of intra-cut rings at the point of impingement of the mixture inside the integrated oil separator to restrict the flow of the mixture. The intra-cut rings control the flow distribution of the mixture as it deflects and moves further at reduced velocity. This helps in better separation in both gravity separation & mesh separation stage as flow gets

uniformly distributed and the mixture further flows circumferentially and reach the mesh uniformly.
Fig. 2 describes a typical subsystem 200 such as chiller connections with different components comprising a compressor 212 coupled with an oil separator in a HVAC system. The outer shell 202 is depicted with plurality of entry points (hereinafter "outer shell inlet/s") (shown in Fig. 3(a) as 312) connected to an inlet distributor 210 for uniform distribution of mixture into the outer shell 202. A connecting pipe 208 supplies the mixture from the compressor 212 to the inlet distributor 210. Side closing ring plates 206(a) and 206(b) shown in fig. 3(a)) close a first open end and a second open end respectively to confine the mixture to circumferentially flow between the outer shell 202 and the inner shell 204.
Fig. 3(a) and Fig. 3(b) depict a typical separation mechanism of oil and refrigerant from the mixture in a typical circumferential flow integrated oil separator 300. Fig. 3(a) depicts an exemplary longitudinal sectional view of the condenser with circumferential flow integrated oil separator 300 with components and Fig. 3(b) depicts an exemplary sectional side view of the condenser with circumferential flow integrated oil separator 300 according to an exemplary embodiment of the invention. The working of the circumferential flow integrated oil separator 300 having an inner shell 204 extending along a length of the outer shell 202 to separate the oil and the refrigerant from the mixture is explained below. The mixture enters through the inlet distributor 210 and further enters into the outer shell 202 from the outer shell inlets 312(a), 312(b)...312(n) (in combination known as 312) connected to the inlet distributor 210. However, the working of the oil separator 300 with a single outer shell inlet is similar to working with the multiple outer shell inlets 312 of the oil separator 300 and is within the scope of the invention. The mixture enters the oil separator impinging onto the outer wall of the inner shell 204, and flows circumferentially between the inner shell 204 and the outer shell 202. The mixture impinges and flows in different directions circumferentially between an inner wall of the outer shell and an outer wall of the inner shell 204. In an exemplary

embodiment, the direction of flow of the refrigerant and oil mixture may be circumferentially up as it may separate the mixture in most efficient way.
The circumferential flow utilizes the length of condenser shell reduces the height of oil separator having same cross-sectional area. It therefore results in reduced shell diameter as well as cost saving. The mesh height used by the circumferential flow oil separator is smaller than conventional oil separators for same velocity at mesh entrance. Thus, the minimum required distance to mesh is much smaller for circumferential flow oil separator than that of conventional oil separator. In other words, the minimum required time to reach the mesh is smaller for circumferential flow oil separator than that of conventional oil separator.
In circumferential flow oil separator, the actual distance travelled by mixture to the mesh is through the circumferential path around the inner cylindrical shell. The circumferential flow provides the mixture an opportunity to travel sufficient distance before it reaches to mesh 314. Therefore, the actual distance travelled by oil droplet is more than the required distance to mesh. Large & heavy oil droplets separates from the mixture under the influence of gravity. Thus, gravity separation criteria are easily met.
At least one mesh 314 is positioned longitudinally along the length of the outer shell 202 to receive the mixture from each direction. Further, the at least one mesh 314 may comprise plurality of meshes. The plurality of meshes 314 filter the oil from the mixture and allow remaining separated refrigerant to pass through the mesh into an inlet 318 of the inner shell. At least one oil outlet 320 is located on the outer shell 202 to escape the separated oil to flow outside the outer shell 202. The outer shell 202 is placed in slightly tilted position so that the separated oil may easily flow out from the oil outlet 320. The plurality of meshes are arranged in such a way that the inner shell inlet 318, located on the inner shell 204 is positioned between the plurality of meshes to receive the separated refrigerant into the inner shell 204 for condensation. The inner shell 204 comprises a plurality of tubes 316 through which fluid to absorb heat from the refrigerant flows, thereby the refrigerant condenses. At least one refrigerant outlet 306 allows the condensed refrigerant to flow outside

the inner shell 204 as well as outer shell 202. The side closing ring plates 206(a) and 206 (b) close a first open end and a second open end respectively to confine the mixture to circumferentially flow between the outer shell 202 & inner shell 204. Fig. 3(b) shows the circumferential flow of the mixture divided in different directions.
Fig. 3(a) and Fig. 3(b) depict, a typical inner shell with circumferential flow integrated oil separator having the inner shell as a pressure part. The tube sheets 308(a) and 308(b) are welded to a first open end and a second open end respectively of the inner shell 204 to resist the refrigerant from flowing outside.
Fig. 4(a) and Fig. 4(b) depict, a typical inner shell with circumferential flow integrated oil separator 400 having the inner shell 204 as a non-pressure part. The tube sheets 308(a) and 308(b) are welded to a first open end and a second open end respectively of the outer shell 202 to resist the refrigerant from flowing outside. The working principle is same as explained above for Fig. 3(a) and Fig. 3(b) and repetition is avoided for brevity.
It is possible to design the oil separator as the present disclosure to keep the mesh area, flow rate and velocity same as in conventional/ existing oil separator. A large saving in oil separator height is possible due to use of longer mesh. Thus, the shell diameters can be reduced significantly. The reduced shell diameter results in size reduction of the tube sheets, water box, end casing. The reduction in diameter also results in reduction in the required thicknesses of shell, tube sheet, water box & end casing. There can be an additional cost saving due to U tube design (800) as disclosed in fig. 8, reduction in sizes of saddles, gaskets, inner ring, tubes, insulation. As compared to existing product a double inlet discharge piping is not required. This also saves discharge copper or steel piping & brazing joints.
Therefore, some of the technical benefits achieved by implementing the present disclosure are that the large size refrigerant inlet/s (318) to condenser may be implemented which reduces the velocity (V) at condenser shell entrance. With lower kinetic energy per unit volume i.e. rho x V2 value the probability of failure due to flow induced vibrations in the present system is nil or minimum. The

impinging plate requirement to protect tube bundle against impinging fluid (refrigerant vapor) is also eliminated. The pressure-drop on refrigerant side is lower and therefore higher coefficient of performance (COP) may be achieved. As the condenser shell is placed inside the oil separator shell, there is no probability of internal leakage leading to higher oil carry over as oil is outside the condenser and therefore, no welding is done on the inner shell 204. There may be flexibility to add more number of tubes to upgrade performance in the same size shell. Hence, it may be possible to develop a reduced weight and smaller size of chiller as disclosed in different embodiments of the present invention. Since overall internal volume of the chiller with circumferential oil separator is lower than that of conventional oil separator, the refrigerant charge requirements are also lowered.
As per Stokes's law terminal velocity (Vt) is derived as follows:
_ gd% (Pi - Pg) ' ~ 18M5
Where,
Vt = Terminal velocity
g = Acceleration due to gravity
dp = Diameter of oil particle
pi = Density of liquid (Oil)
pg = Density of gas (Refrigerant gas)
Vg = Gas velocity = Flow rate/cross section area
Vg and Vt remains same for conventional as well as the present disclosure design as all the above parameters are same for both cases.
trg \-iQi V g
wherein trg is actual time to mesh also known as residence time and Le is distance to mesh.
tf(max) = hg/Vt

wherein tf(max) is minimum required time to the mesh also known as maximum time to fall and hg is mesh height.
The oil particles separate from the mixture by gravity if
trg ^ tf (max)
i. e. (Actual time to mesh) > (Minimum required time to mesh).
Since mesh height (hg) is smaller in present design, the minimum required distance to mesh (Le) needs to be smaller in proportion to hg. Thus, actual time to mesh can be kept more than required time to mesh. Therefore, the gravity separation criterion is satisfied in the present disclosure design and the oil is separated from the refrigerant and oil mixture by virtue of gravity before it reaches the mesh 314.
It is noted that since, the mesh area is same in both designs, mesh depth and mesh volume also remain the same in conventional as well as the present disclosure. Therefore, there is no additional cost required for the mesh 314 used in the present disclosure design. Mesh separation efficiency also remains the same.
Therefore, the present disclosure is designed with much smaller shell diameter (lower cost) that may achieve same separation efficiency as conventional larger & costlier oil separators.
Fig. 5 depicts an exemplary embodiment 500 of the present invention showing one or more baffles 502, 504 arranged in a series on the inner wall of the outer shell and the outer wall of the inner shell respectively. Suppose the distance between the inner wall of the outer shell 202 and the outer wall of the inner shell 204 is D, the height of the baffles in the exemplary embodiment may be greater than D/2 to restrict the circumferential flow of mixture between the two shells. In an exemplary embodiment, the baffles 502 on the inner wall of the outer shell and the baffles 504 on the outer wall of the inner shell are arranged alternatively and placed at some distance from each other. The mixture during the circumferential flow, flows through the baffles 502 and 504. The baffles 502, 504 leads extra pressure drop on the mixture that restrict oil particles at baffles allowing refrigerant rich mixture to

reach the mesh 314 for filtration. Thus, the baffles increase separation efficiency in a flow path of the mixture.
Fig. 6(a) and Fig. 6(b) depicts a sectional front view and a sectional side view of an exemplary embodiment 600, that shows an inner shell 204 and an outer shell 202 are eccentric. Due to the design, the flow of mixture may be non-uniform in different directions. Depending on the application of use, the flow of mixture may be unidirectional in case the inner shell 204 comes in contact with the inner wall of the outer shell 202. The separation principles are same i.e. gravity & mesh as discussed earlier.
In an embodiment of the invention, the inner shell 204 can be a non-pressure part. In this case, the inner shell 204 and the outer shell 202 are welded with side closing ring plates placed inside the outer shell 202 to confine and leakproof the circumferential flow passage. Tube sheets are welded to the outer shell 202. In another embodiment of the invention, the inner shell 204 can be a pressure part. In this case, the inner shell 204 and outer shell 202 are welded with side closing ring plates placed outside the outer shell 202 to confine and leakproof the circumferential flow passage. Tube sheets are welded to the inner shell.
Fig. 7(a) and Fig. 7(b) depict the exemplary embodiments of an eccentric shells showing the inner shell 204 is displaced from the central axis of the outer shell near to the inner wall of the outer shell 202 but not touching the inner wall of the outer shell. The mixture received from the outer shell inlet/s 312 may flow non uniformly towards the inlet of the inner shell. This eccentric design results in progressively increasing cross section area as the mixture moves between the inner shell and the outer shell.
In another exemplary embodiment, as shown in Fig. 8, the heat transfer tubes inside the inner shell are U-shaped. Therefore, the heat transfer liquid enters the tubes from one side and comes out from the same side. In such a case, the inner shell 204 may also be a pressure part. Therefore, the end casing and tube sheet are required only on one side of the inner shell 204.

Fig. 9 depicts the exemplary embodiment showing a front section view 900 of an oil separator with the mesh 314. The mesh 314 may comprise one or more mesh breaker 902 for flow partition. Also, the mesh partition 902 may be used with standard size mesh available. In another embodiment, the oil is separated from the refrigerant and oil mixture by virtue of gravity and further by filtration using the at least one mesh 314. The flow of the mixture is same as discussed with respect to Fig. 3(a) and Fig. 3(b) above.
Fig. 10 depicts a flowchart outlining the features of the invention in an exemplary embodiment. The method flowchart describes a method 1000 being performed to separate the oil and the refrigerant from the refrigerant and oil mixture to increase the efficiency of the refrigeration system. The method starts at 1002 by allowing the refrigerant and oil mixture to enter inside the oil separator through inlet 312. This is explained in greater detail in Figs. 2-5 above.
At step 1004, the circumferential flow of the mixture is defined between the outer shell 202 and the inner shell 204. The refrigerant and oil mixture on entering the oil separator impinges onto the outer wall of the inner shell and flows circumferentially between the outer wall of the inner shell and the inner wall of the outer shell. The inner shell 204 extends along length of the outer shell 202.
At step 1006, the refrigerant and oil mixture velocity may be reduced, and the oil starts to separate and settle down by gravity. Larger and heavier oil droplets may settle down quickly by gravity then progressively smaller and lighter droplets of oil. The separated oil drips down and gets accumulated on the inner wall of the outer shell 202 of the oil separator. The oil starts to flow towards the oil outlet 320.
The outer shell 202 is slightly inclined with respect to inner shell 204 towards the oil outlet 320 to ease the escape of oil from the outer shell 202. This has been discussed in greater details in Figs. 2-5 above. The lighter oil droplets in the refrigerant and oil mixture further reach towards the mesh for next stage of oil separation.

At step 1008, the oil is filtered and separated from the refrigerant and oil mixture using the one or more meshes 314. The refrigerant being in gaseous state may easily flow through the mesh having fine mesh wires without much resistance whereas the oil droplets being in liquid state find it difficult to alter its path around the mesh wires and get trapped and separate out. The separated oil droplets in the mesh falls down on the inner wall of the outer shell to form an oil pool in the outer shell 202 of the oil separator.
At step 1010, the separated refrigerant from the one or more meshes 314 enters inside the inner shell 204 for condensation, wherein the refrigerant in the inner shell 204 after condensation escapes through the refrigerant outlet 306.
Figs. 11, 12 and 13 depict different method flowcharts outlining the features of the invention in an exemplary embodiment. Many modifications to the manufacturing methods, sequence of manufacturing operations described here are possible. The methods described here are for illustration for ease of understanding and should not be considered in limiting sense.
Fig. 11 depicts an exemplary flowchart illustrating a method 1100 for manufacturing an inner shell 204 with a circumferential flow integrated oil separator according to an exemplary embodiment. The method flowchart describes a method 1100 of manufacturing of the the inner shell 204 with a circumferential flow integrated oil separator 300 or 400. The method 1100 starts at 1102 by placing a first half outer shell 202(a) of the integrated oil separator in an inverted position on a fixture for manufacturing. The inverted position means a part is rotated by 180 degrees in vertical direction than working position. At step 1104, a set of mesh brackets and/or holders are welded in the inverted first half outer shell 202(a). The one or more meshes 314 are inserted inside the first half outer shell 202(a). At step 1106, an inner shell assembly also known as a condenser shell assembly is placed over and inside the first half outer shell 202(a) in inverted position to sandwich the meshes 314 At step 1108, a second half outer shell 202(b) is placed longitudinally in inverted position on the first half outer shell 202(a). At step 1110, the first half outer shell 202(a) and the second half outer shell 202(b) are welded longitudinally

to join the two half outer shells 202(a) and 202(b). At step 1112, the inner shell assembly is closed by welding the first side plate 206(a) and the second side plate 206(b). At step 1114, the tube sheets are welded on both the ends of the outer shell 202 in case the inner shell 204 is a non-pressure part. At step 1114, the tube sheets 308(a) and 308(b) are welded on both the ends of the inner shell 204 in case the inner shell 204 is a pressure part. At step 1116, tubes may be inserted in inner shell 204, expansion and other manufacturing operations may be completed. At step 1118, a pneumatic pressure testing is done on sub-assembled inner shell with a circumferential flow integrated oil separator assembly 300 or 400 on shell side by blanking off nozzle opening to check any leakages. Once the sub-assembly passes the shell side pressure test, at step 1118, the end casings are bolted to complete the sub-assembly at step 1120. A hydro test on tube side may also be performed at step 1120.
In another embodiment of the present invention, a method 1200 for manufacturing of the inner shell with a circumferential flow integrated oil separator 300 or 400 is disclosed. Fig. 12 depicts a flowchart 1200 for assembling method. At step 1202, the inner shell assembly may be placed on a fixture for manufacturing. At step 1204, the one or more mesh brackets may be welded on the outer wall of the inner shell assembly and the one or more mesh 314 may be inserted in the welded brackets. At step 1206, the outer shell 202 may be slided over the inner shell assembly. At step 1208, the outer shell 202 may be moved in a way to extend nozzle of the inner shell 204 to come out of the outer shell 202. At step 1210, the outer shell may be adjusted to sandwich one or more meshes between the outer shell 202 and the inner shell assembly. At step 1202, the assembly may be closed by welding the first side plate 206(a) and the second side plate 206(b) on both ends of the outer shell 202. At step 1214, the tube sheets may be welded on both the ends of the outer shell 202 in case the inner shell 204 is a non-pressure part. At step 1214, the tube sheets 308(a) 308(b) may be welded on both the ends of the inner shell 204 in case the inner shell 204 is a pressure part. At step 1216, inner shell tube insertion, expansion and other manufacturing operations may be completed. At step 1218, a pneumatic pressure testing may be done on sub-assembled inner shell with the circumferential flow

integrated oil separator 300 or 400 on shell side by blanking off nozzle opening to check any leakages. Once the sub-assembly passes the shell side pressure test, at step 1218, the end casings may be bolted to complete the assembly at step 1220. A hydro test on tube side may be also completed at step 1220.
The method 1200 may be used for concentric as well as eccentric manufacturing process of the inner shell assembly with the outer shell assembly.
Fig. 13 depicts yet another embodiment of a method 1300 for manufacturing an inner shell with a circumferential flow oil separator having a prefabricated internal oil separator. At step 1302, the inner shell assembly may be placed on a fixture for manufacturing. At step 1304, a pre-fabricated oil separator may be placed over the inner shell assembly and welded with the inner shell assembly. At step 1306, the outer shell 202 may be slided over the pre-fabricated oil separator and the inner shell assembly. At step 1308, the outer shell 202 may be moved in a way to extend nozzle of the inner shell 204 to come out of the outer shell 202. The outer shell 202 may be adjusted to settle properly with pre-fabricated oil separator and the inner shell assembly. At step 1310, the outer shell may be closed by welding the first side plate 206(a) and the second side plate 206(b) on both ends of the outer shell 202. At step 1312, the tube sheets may be welded on both the ends of the outer shell 202 in case the inner shell 204 is a non-pressure part. At step 1312, the tube sheets 308(a) 308(b) may be welded on both the ends of the inner shell 204 in case the inner shell 204 is a pressure part. At step 1314, inner shell tube insertion, expansion and other manufacturing operations may be completed. At step 1316, a pneumatic pressure testing may be done on the sub-assembled inner shell with a circumferential flow oil separator on shell side by blanking off nozzle opening to check any leakages. Once the sub-assembly passes the shell side pressure test, at step 1316, the end casings may be bolted to complete the assembly at step 1318. A hydro test on tube side is also completed at step 1318.
The present invention is applicable in various industries/fields such as, but is not limited to, hospitality industry, residential complexes, offices, universities,

hospitals, colleges, homes and any such industry/field that is well known in the art and where the HVAC systems are used.
The embodiments of the invention discussed herein are exemplary and various modification and alterations to a person skilled in the art are within the scope of the invention. Though the present invention has been described considering an exemplary refrigeration system, still the invention is applicable to all the internal oil separators which can incorporate the condensers.
When introducing elements of aspects of the invention or the examples thereof, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements. The term "exemplary" is intended to mean "an example of." The phrase "one or more of the following: A, B, and C" means "at least one of A and/or at least one of B and/or at least one of C".
Having described aspects of the invention in detail, it will be apparent that modifications and variations are possible without departing from the scope of aspects of the invention as defined in the appended claims. As various changes could be made in the above constructions, products, and methods without departing from the scope of aspects of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
Although the subject matter has been described in language specific to structural features and/or acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as examples of implementing the claims and other equivalent features and acts are intended to be within the scope of the claims.

We Claim:

1. An apparatus for heating, ventilation, and air conditioning (HVAC) system,
the apparatus comprising:
an inner shell extending along a length of an outer shell;
at least one outer shell inlet configured to allow refrigerant and oil mixture to enter into the outer shell, wherein the refrigerant and oil mixture impinges onto an outer wall of the inner shell and flows circumferentially between an inner wall of the outer shell and the outer wall of the inner shell;
at least one mesh, arranged between the inner shell and the outer shell along the length of the outer shell, and configured to separate oil and refrigerant from the refrigerant and oil mixture; and
at least one inner shell inlet to allow the separated refrigerant to enter inside the inner shell for condensation.
2. The apparatus of claim 1, wherein the refrigerant and oil mixture flows and splits to move in different directions circumferentially between the inner wall of the outer shell and the outer wall of the inner shell.
3. The apparatus of claim 2, wherein the at least one mesh is positioned longitudinally to receive the refrigerant and oil mixture from each direction.
4. The apparatus of claim 3, wherein the at least one mesh comprises two or more meshes, wherein the at least one inner shell inlet located on the inner shell is positioned between the two meshes to transfer the separated refrigerant into the inner shell for condensation.
5. The apparatus of claim 1, wherein the inner shell is concentric with the outer shell.
6. The apparatus of claim 1, wherein the inner shell is eccentric with the outer shell.

7. The apparatus of claim 1, wherein the outer shell comprises at least one outlet configured to allow separated oil from the refrigerant and oil mixture to flow outside the outer shell and at least one outer shell inlet located on the outer shell.
8. The apparatus of claim 1, comprising one or more baffles arranged in a series on the inner wall of the outer shell and the outer wall of the inner shell.
9. The apparatus of claim 1, comprising deflectors including plurality of intra cut rings present at the point of impingement of the refrigerant and oil mixture on the outer wall of the inner shell to deflect the refrigerant and oil mixture.
10. The apparatus of claim 9, wherein the deflectors deflect the refrigerant and oil mixture towards different directions.
11. The apparatus of claim 1, wherein the inner shell and the outer shell are cylindrical in shape.
12. The apparatus of claim 1, wherein the oil is separated from the refrigerant and oil mixture by virtue of change in direction, gravity and further by filtration using the at least one mesh.
13. A method comprising:
allowing refrigerant and oil mixture to enter into an outer shell through at least one outer shell inlet;
allowing the refrigerant and oil mixture to flow circumferentially between an inner wall of the outer shell and an outer wall of an inner shell, wherein the refrigerant and oil mixture impinges from the at least one outer

shell inlet onto the outer wall of the inner shell, the inner shell extending along length of the outer shell, and;
separating oil and refrigerant from the refrigerant and oil mixture, using at least one mesh, wherein the at least one mesh is arranged between the inner shell and the outer shell along the length of the outer shell; and
allowing the separated refrigerant to enter inside the inner shell using at least one inner shell inlet for condensation.
14. The method according to claim 13, wherein the refrigerant and oil mixture flows and splits to move in different directions circumferentially between the inner wall of the outer shell and the outer wall of the inner shell.
15. The method according to claim 14, wherein the at least one mesh is positioned longitudinally to receive the refrigerant and oil mixture from each direction.
16. The method according to claim 15, wherein the at least one mesh comprises two or more meshes, wherein the at least one inner shell inlet located on the inner shell is positioned between the two meshes to transfer the separated refrigerant to the inner shell for condensation.
17. The method according to claim 13, wherein the outer shell comprises at least one outlet configured to allow separated oil from the refrigerant and oil mixture to flow outside the outer shell and at least one outer shell inlet located on the outer shell.
18. The method according to claim 13, comprising one or more baffles arranged in a series on the inner wall of the outer shell and the outer wall of the inner shell.

19. The method according to claim 13, comprising deflectors including a plurality of intra cut rings present at the point of impingement of the refrigerant and oil mixture on the outer wall of the inner shell to deflect the refrigerant and oil mixture.
20. The method of claim 13, wherein the oil is separated from the refrigerant and oil mixture by virtue of gravity and further by at least filtration by the one or more mesh.