The invention relates to suction accumulators for refrigeration or air/conditioning system use and is particularly concerned with deflectors used with accumulators.
Closed-loop refrigeration systems conventionally employ a compressor that is meant to draw in gaseous refrigerant at relatively low pressure and discharge hot refrigerant at relatively high pressure. The hot refrigerant condenses into liquid as it is cooled in a condenser. A small orifice or valve divides the system into high and low-pressure sides. The liquid on the high-pressure side passes through the orifice or valve and turns into a gas in the evaporator as it picks up heat. (Some systems operate in “transcritical” mode, in that the hot refrigerant is merely cooled in a high side heat exchanger, now termed a “gas cooler”, and turns to gas plus liquid as it passes through the expansion device.) At low heat loads, it is not desirable or possible to evaporate all the liquid in the evaporator. However, excess liquid refrigerant entering the compressor (known as “slugging”) causes system efficiency loss and can cause damage to the compressor. Hence it is standard practice to include a reservoir between the evaporator and the compressor to separate and store the excess liquid. It is also a reservoir for excess refrigerant, which is typically added to the system during manufacture to compensate for unavoidable leakage during the working life of the system. This reservoir is called a suction line accumulator, or simply an accumulator.
An accumulator is typically a metal can, welded together, and often has fittings attached for a switch, transducer and/or charge port. One or more inlet tubes and an outlet tube pierce the top, sides, or occasionally the bottom, or attach to fittings provided for that purpose. The refrigerant flowing into a typical accumulator will impinge upon a deflector or baffle intended to reduce the likelihood of liquid flowing out the exit, generally by removing kinetic energy from the liquid so it settles quietly into the reservoir area without churning or splashing. Some patents describe accumulators without deflectors (such as U.S. Pat. No. 5,179,844 and U.S. Pat. No. 5,471,854). However, the lack of a deflector reduces effective reservoir volume and reduces efficiency by allowing churning and splashing that returns unnecessary liquid to the compressor—that is, by allowing liquid carryover. Moreover, even when deflectors have been used in the past, the deflectors have contributed to turbulence, when the incoming fluid rebounds off the deflectors.
A consequence of using a suction line accumulator is that compressor oil can become trapped within it. Compressor oil is circulated with the refrigerant in most systems in current usage. Even if a separator is used, a small amount of oil escapes into the system. This oil will find its way into the accumulator, and while liquid refrigerant may be expected to evaporate and return to circulation as needed, the oil does not evaporate. Some means must be provided to return this oil to circulation. A known practice is to use a J-shaped outlet tube to carry the exiting gaseous refrigerant from the top of the accumulator down to the bottom and then back up to the outlet from the accumulator. A carefully sized orifice at the bottom of this “J-tube” (sometimes also referred to as a “U-tube”) entrains the oil from the bottom of the liquid area into the stream of exiting gas. A recent development in accumulator design is to incorporate a plastic liner in the accumulator to assist with the oil pick up function (as shown in U.S. Pat. No. 06,612,128 and 06,463,757).
While previous deflector and accumulator designs have considered configurations to help prevent liquid refrigerant from exiting the accumulator, the previous designs do not appear to have addressed deflector design to improve the separation of liquid from vapour (while maintaining little liquid carryover).
Deflectors within accumulators have typically been designed to act only as shields to protect an outlet tube (or a J-tube or a gas flow tube (all of which may be referred to as a conduit primarily for gas)) from stray liquid refrigerant. It would be desirable to have a deflector that improves the separation of liquid and gas, while also protecting the outlet (or gas flow tube) from liquid refrigerant.
Computational Fluid Dynamics (CFD) calculations were used to study the path of fluid entering an accumulator and its reaction with the deflector surfaces in greater detail than previously. This allowed for a more in-depth study of the critical features of the deflector surfaces, and led to embodiments of the present invention incorporating novel deflector designs with improved configuration of deflector surfaces to disperse a greater amount of kinetic energy, thereby yielding improved gas/liquid separation.
The geometry of an initial contact surface of a deflector according to one embodiment of the present invention provides for inbound refrigerant and oil to be separated into its liquid and gas components with minimal or less interaction with the initial contact surface. The liquid and gas are allowed only minimal interaction upon contact with the deflector to avoid or reduce the likelihood of liquid re-entrainment.
In an accumulator without a liner, the liquid refrigerant and oil are then directed towards or near an inner surface of the accumulator, where gravity pulls the liquid down.
In one type of liner-style accumulator, the liquid refrigerant is then directed to interior walls of a liner while the gas flows toward a gas flow conduit. The oil and liquid refrigerant flow downward due to gravity, along an inside surface of the liner, to the bottom of the liner, while the gaseous refrigerant migrates toward an inlet of the gas flow conduit. The gas flow conduit is designed to direct the gas downward, underneath the liner. As gas flows under the liner, oil is entrained within the gas flow, through an oil bleed orifice located at or near a zenith in the liner.
In accordance with another aspect of the present invention, a deflector is provided for an accumulator where deflector surfaces disperse a greater amount of kinetic energy (than previous designs), thereby yielding improved gas/liquid separation.
Embodiments of the accumulators and related designs described herein could be used in air conditioning systems within vehicles. Embodiments of the accumulators and related designs described herein could also be used in stationary air conditioning and/or refrigeration systems (commercial and industrial).
According to a further aspect, the invention provides an accumulator for an air conditioning system, the accumulator comprising an outer body, a liner inside and spaced from the outer body, a conduit primarily for gas, and a deflector comprising a generally cylindrical circumference with an inner surface, wherein the inner surface of the circumference of the deflector is adjacent an inside surface of the liner and the deflector further comprising a separation/protection means to separate liquid from gas, wherein a portion of the separation/protection means comprises a barrier to substantially prevent liquid from entering the conduit and a portion of the separation/protection means comprises an initial contact surface for directing fluid away from a flow of incoming fluid, wherein the initial contact surface is substantially convex across the initial contact surface and the initial contact surface, as seen from an upper edge to a lower edge thereof, is angled away from the flow of incoming fluid.
According to a further aspect, the invention provides an accumulator for an air conditioning system, the accumulator comprising an inlet to supply incoming fluid, the inlet being located on a side of the accumulator, the accumulator further comprising a deflector and a conduit primarily for gas, the deflector comprising a separation/protection means to separate liquid from gas, wherein the separation/protection means comprises a barrier to substantially prevent liquid from entering the conduit and the separation/protection means comprises an initial contact surface for directing fluid down and away from a flow of incoming fluid, wherein the initial contact surface is substantially convex across the initial contact surface and the initial contact surface, as seen from an upper edge to a lower edge thereof, is angled away from the flow of incoming fluid.
According to yet another aspect, the invention provides an accumulator for an air conditioning system, the accumulator comprising: a deflector, a conduit primarily for gas, an outer body, an inlet to supply incoming fluid, the inlet being located within a top of the outer body to direct incoming fluid downward, and a separation/protection means to separate liquid from gas, the separation/protection means comprises a barrier to substantially prevent liquid from entering the conduit and a portion of the separation/protection means comprises an initial contact surface for directing fluid down and away from a flow of incoming fluid, wherein the initial contact surface is located generally opposite the inlet and the initial contact surface is substantially convex across the initial contact surface and slopes downward and outward to direct fluid in a direction away from an entrance of the conduit, and the initial contact surface as seen from an upper edge to a lower edge thereof, is angled away from the flow of incoming fluid, and the barrier of the separation/protection means comprises a wall extending across the deflector, with the inlet being located on one side of the barrier and an opening of the conduit being located on the other side of the barrier.
Different embodiments of the present invention may provide some of the following features and advantages: an accumulator having a deflector where the deflector not only helps prevent liquid from flowing directly into a conduit for gas, but also helps separation of liquid from gas; a deflector for an accumulator, where the configuration of the deflector disperses kinetic energy to provide improved liquid/gas separation; a deflector for an accumulator designed to separate liquid from gas with less interaction between the liquid and gas or with less turbulence to avoid or reduce the likelihood of liquid re-entrainment with the gas; an accumulator having a gas flow tube inside the accumulator where an entrance to the gas flow tube is located near a top of the accumulator, thereby increasing the effective accumulator volume (because a greater volume of liquid can be stored in the accumulator without the liquid flowing into the gas flow tube); an accumulator providing improved performance; an accumulator which is relatively easy to manufacture and fits multiple installation configurations; an accumulator which is more cost-effective and more flexible.
Preferred embodiments of the invention will now be described with reference to the attached drawings in which:
a is a perspective view of a side-in-side-out (SISO) accumulator (with some of the internal components shown in dotted outline) in accordance with an embodiment of the present invention;
b is a vertical sectional view of the accumulator of
c is an exploded view of the accumulator of
a-2f are different views of the SISO deflector of
a is a perspective view looking down;
b is a perspective view looking up;
c is a top view;
d is a perspective sectional view;
e is a bottom view looking up; and
f is a side view of the initial contact surface;
a-4d are different views of a TISO deflector for the accumulator of
a is a perspective view;
b is a perspective sectional view;
c is a top view; and
d is a bottom view;
a is a perspective view of a TISO J-tube style accumulator, with a portion of the accumulator top and bottom canisters removed for greater clarity, in accordance with another embodiment of the present invention;
b is a perspective view of the J-tube and deflector of
c is a perspective view of the J-tube and deflector of
a is a perspective view of a SISO style accumulator, with a portion of the accumulator top and bottom canisters removed for greater clarity, in accordance with another embodiment of the present invention;
b is a perspective view of the J-tube and deflector of
As shown in
Within the accumulator 20 are (among other possible features): a liner 36, which is secured within the bottom canister 24 of the accumulator 20; a deflector 40, which is secured near a top portion of the accumulator 20; and a gas flow tube or conduit 42, which extends within the accumulator 20, partway along the height of the accumulator 20. The accumulator may also incorporate a desiccant container 44.
As shown in
As suggested in
The deflector 40 in this embodiment has an inlet entrance 64, being generally unshaped and projecting out from the outer wall 60. The inlet entrance 64 could assume other shapes, provided that fluid entering the accumulator 20 is directed into the deflector 40.
Two vertical deflector ribs 66 are shown extending outward from the outer wall 60. The vertical deflector ribs 66 are adapted to ensure that the deflector 40 fits securely within the top canister 22. Other or additional means could also be used to secure the deflector 40 within the top canister 22.
An initial contact surface 70 (which may also be referred to as a separation/protection means) extends across a portion of the deflector 40, from one portion of the inner surface 63 of the outer wall 60 to another portion of the inner surface 63. The initial contact surface 70, in this embodiment, is generally centered (in the left-right orientation, as seen in
A gas flow tube socket 74 is supported within the deflector 40. In this embodiment, the gas flow tube socket 74 is part of deflector 40, although it need not be. The gas flow tube socket 74 has an opening 76, adapted to fit securely around a top portion of the gas flow tube 42. A generally cylindrical wall 80 defines the socket opening 76. A step 81 (as shown in
The opening 76 of the socket 74 is located below the top edge 73 of the initial contact surface 70.
Advantageously, the deflector 40 (and/or the top canister 22) may have a means known to those skilled in the art (not shown) to help ensure that the inlet tube 28 and/or the inlet fitting 26 is/are tightly sealed so that all fluid from the inlet tube 28 is directed into the deflector 40.
The deflector may be made from a suitable plastic, metal, or other material. Advantageously, the material chosen for the deflector will have similar expansion properties as the material(s) used to manufacture the accumulator, so that both the accumulator and the deflector will expand or contract in a comparable manner in response to the application of heat or cold.
The accumulator 20 may be assembled as generally suggested by
The gas flow tube 42 is then inserted through the opening formed within the desiccant container 44. The outer diameter of the gas flow tube 42 is sized such that it is slightly smaller than the inner diameter of the opening formed within the desiccant container 44, but still forms a tight seal between the two surfaces.
The deflector 40 then slides into position within the liner 36. The lower portion 61 of the deflector 40 is sized to fit securely within a top portion of the liner 36. A top edge of the liner 36 rests against the step 62 of the deflector 40. The gas flow tube 42 fits securely within the opening 76 of the gas flow tube socket 74. The flared upper surface 82 of the socket 74 reduces the pressure drop across the opening to the outlet tube 42.
The liner 36 is then placed within the bottom canister 24. There is a gap between an inside surface of the bottom canister 24 and the outer surface 46 of the liner 36 defined or determined (in this embodiment) by the extent to which the liner ribs 54 project from the outer surface 46. The size of the gap may be adjusted. The larger the gap, the smaller the pressure drop through the accumulator 20, at the expense of the volume within the liner 36.
The top canister 22 is secured to the bottom canister 24. Advantageously, there is a fitting or other adaptation (not shown) to help ensure a fluid-tight seal between a top edge of the deflector 40 and an inside surface of the top canister 22. This helps prevent liquid carryover and may allow a top of the gas flow tube 42 to be near a top of the top canister 22, thereby increasing the effective accumulator volume, because a greater volume of liquid can be held in the accumulator without the liquid entering the gas flow tube 42. The top canister 22 is positioned on the deflector 40 such that the inlet entrance 64 of the deflector 40 meets up with and seals around inlet fitting 26 of the top canister 22.
The top canister 22 and the bottom canister 24 may be made of aluminum or steel, for example, and welded together to form a hermetic seal.
In operation, fluid enters the accumulator 20 through inlet tube 28. The arrows shown in
The design of the deflector 40, as described above, dissipates kinetic energy and improves the degree to which gaseous refrigerant is initially separated from liquid refrigerant and oil. Moreover, the shape or geometry of the initial contact surface 70 provides improved liquid/gas separation with less turbulence and reduced re-entrainment of gas with liquid. In other words, the liquid fluid is separated from the gaseous fluid with relatively minimal interaction with the gaseous refrigerant to avoid liquid re-entrainment.
When fluid flows into the initial contact surface 70, the liquid refrigerant and oil are directed down to the interior walls of the liner 36, while the gaseous refrigerant is separated and directed towards the gas flow tube 42. The oil and liquid refrigerant then flow downward due to gravity, typically along the inside surface of the liner 36. The liquid refrigerant and oil pass through the desiccant container 44, which removes moisture from the liquid refrigerant, and the liquid then settles on the floor of the liner 36.
Meanwhile, gaseous refrigerant flows into the opening 76 of the socket 74 and then down and out the gas flow tube 42 below the liner 36. The gaseous refrigerant then flows up through the gap between the liner 36 and the bottom canister 24 and then up to the outlet fitting 30, whereupon, the gaseous refrigerant exits the accumulator though the outlet conduit (not shown). As the gaseous refrigerant flows past the oil bleed orifice (not shown) near the nadir of the liner 36, oil (and possibly some liquid refrigerant) passing through the oil bleed orifice is entrained within the flow of gaseous refrigerant, and is carried up and out the outlet conduit (not shown) with the gaseous refrigerant.
The embodiments described above relate to a side-in-side-out (SISO) accumulator. However, the principles described above could also be applied to accumulators having other configurations. For example, a vertical, sectional view of a particular top-in-side-out (TISO) liner style accumulator is shown in
Different views of the TISO deflector 94 are shown in
A separation wall 112 extends across the deflector 94, from one portion on the inner surface 110 to another portion on the inner surface 110. The separation wall 112 has a wavy shape, as shown in the top view of
An initial contact surface 114 extends between the separation wall 112 and the inner surface 110 of the outer wall 96. The initial contact surface 114, as described below, is shaped so that liquid on the initial contact surface 114 flows towards, and then down, the inner surface 110 of the outer wall 96.
The combination, in this embodiment, of the separation wall 112 and the initial contact surface 114 may be referred to as a separation/protection means.
The initial contact surface 114 has an apex line (or ridge) 116. In this embodiment, the initial contact surface 114 is generally symmetrical about the apex line 116. Flow directing surfaces 118 and 120 are sloped both downward and towards the inner surface 110 of the outer wall 96. An outer flow directing surface 122 is positioned between the separation wall 112 and the flow direction surface 120, on each side of the apex line 116. Each outer flow directing surface 122 is sloped downward and towards its corresponding flow directing surface 120.
The overall shape of the initial contact surface 114 is substantially convex (in the direction across the initial contact surface 114), even though portions of the initial contact surface 114 may not be convex.
As shown in the top view of
In operation, the deflector 94 and a top canister 132 of the accumulator 90 fit together so that the top edge of the separation wall 112 and the top edge of the outer wall 96 form a fluid tight seal against the top canister 132 (or against a fitting (not shown) within the top canister 132). Fluid from the inlet tube 92 is directed down into the accumulator 90, between the separation wall 112 and the inner surface 110 of the outer wall 96.
Fluid is directed towards the initial contact surface 114, where gaseous refrigerant is mostly (or at least partly) separated from liquid refrigerant and oil. The gaseous refrigerant flows though the fluid openings 124 formed in the deflector 94 and then into the socket opening 130 and down the gas flow tube 42 and then proceeds as described above with respect to the SISO accumulator 20. The liquid refrigerant and oil, upon hitting the initial contact surface 114, flow down the initial contact surface 114 to the inner surface 110 of the outer wall 96. The liquid refrigerant and oil then flow down the inner surface 110 and then down the inner surface of the liner 36 and then proceed as described above with respect to the SISO accumulator 20.
The embodiments of deflectors described above relate to a particular type of liner-style accumulators. However, the principles described above could be applied to a liner style accumulator of any type. In those cases, the configuration of the deflector may be modified to accommodate the particular features of the different types of liner-style accumulators.
Moreover, the deflector design principles described above could also be applied to accumulators that do not incorporate liners. In other words, the principles described above could be applied to other situations where it would, for example, be desirable to separate gaseous fluid from liquid fluid with minimal (or less) re-entrainment of liquid fluid with gaseous fluid and/or with less churning of the separated liquid fluid. For a J-tube style accumulator, the deflector would be adapted to protect an inlet of a J-tube from liquid entering the accumulator. Because a J-tube style accumulator does not typically incorporate a liner, a deflector used in such a liner would likely be modified from the designs described above. For example, the outer wall 60 of the deflector 40 shown in
Alternatively, in an accumulator without a liner, it would not be necessary for a deflector to have a surrounding outer wall, such as outer wall 60 as shown in
An embodiment of one such SISO J-tube style accumulator is shown in
Similarly, a TISO accumulator without a liner could also use the concepts described above. For example, the deflector 94 shown in
a shows a J-tube style accumulator 138, having a top canister 139 and a bottom canister 140. The accumulator 138 incorporates a J-tube 144 (which could also be referred to as a U-tube). The accumulator 138 has an inner surface 142. The accumulator 138 has a deflector 146, having a separation wall 150 and an initial contact surface 152. The deflector 146 in this embodiment is substantially similar to the combination of the separation wall 112 and the initial contact surface 114 of the TISO deflector 94 of
The deflector 146 shown in the embodiment of
Numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein. For example, the embodiments of the accumulator designs described above have a single inlet. However, different embodiments could have more than a single inlet.