ES2440241T3 - Improved refrigerant distribution in parallel flow heat exchanger manifolds - Google Patents

Abstract

A refrigerant system (20) comprising: a condenser (24; 124; 224; 324; 424; 524); a compressor (22); an expansion device (26); and an evaporator (28), the compressor for delivering a compressed refrigerant to the condenser, the refrigerant from said condenser passes through the expansion device, and from said expansion device through the evaporator, and from said evaporator is returned to said compressor; and at least said condenser or said evaporator having a plurality of heat transfer tubes (32, 36, 38, 40) passing a refrigerant downstream in a generally parallel manner; and at least one location (30B, 34A, 34B, 34) within said evaporator (28) that is likely to receive separate vapor and liquid phases of the refrigerant mixture when the refrigerant flows through the plurality of heat transfer tubes. , characterized in that at least a part of the separated vapor phase is taken from said location and delivered to a downstream location (30C, 34B; 30; 25) without passing through at least some of the heat transfer tubes to improve the distribution of a remaining refrigerant flowing through the omitted heat transfer tubes that are in direct fluid communication with this location.

Description

Improved refrigerant distribution in parallel flow heat exchanger manifolds

Background of the invention

This application is related to multi-step parallel flow heat exchangers in refrigerant systems, where the liquid and vapor coolant phases are undesirably separated into one or more intermediate manifolds, resulting in poor distribution of the refrigerant between the heat transfer pipes downstream and a consequent degradation of the heat exchanger performance. In particular, this request is related to the change of route of one of the refrigerant phases (the liquid phase for the condensers and the vapor phase for the evaporators) from at least one intermediate manifold to one or more downstream locations, without going through one or more banks of heat transfer tubes inside the parallel flow heat exchanger and subsequently allowing the uniform distribution of the remaining coolant predominantly from a single phase (the vapor phase for the condensers and the liquid phase for the evaporators) between parallel heat transfer tubes that are located downstream and are in fluid communication with at least one intermediate manifold. This improves the performance of the coolant system as a whole and the heat exchanger.

Coolant systems use a coolant to condition a secondary fluid, such as air, that is delivered to an air-conditioned space. In a basic refrigerant system, the refrigerant is compressed in a compressor, and flows downstream to a condenser, in which heat is typically extracted from the refrigerant to the environment, during the heat transfer interaction with this environment. The refrigerant then flows through an expansion device, in which it expands at a lower pressure and temperature, and to an evaporator, in which during the heat transfer interaction with another secondary fluid (eg air in the inside), the refrigerant evaporates and typically overheats, while cooling and often dehumidifies this secondary fluid.

In recent years, much of the interest and design effort has focused on the efficient operation of heat exchangers (condensers and evaporators) in refrigerant systems. A relatively recent advance in heat exchanger technology is the development and application of parallel flow heat exchangers, or so-called microchannels or mini-channels, (these two terms are used interchangeably in the text), such as condensers and evaporators. .

These heat exchangers are provided with a plurality of parallel heat transfer tubes, typically non-round, between which the refrigerant is distributed and flows in parallel. The heat transfer tubes are generally oriented substantially perpendicular to the flow direction of the refrigerant in the inlet, outlet and intermediate manifolds that are in fluid communication with the heat transfer tubes. The main reasons for the use of parallel flow heat exchangers, which usually have a strong welded aluminum construction, are related to their superior performance, a high degree of compactability, structural rigidity and greater corrosion resistance.

When used in many condenser and evaporator applications, these heat exchangers are usually designed for a multi-step configuration, typically with a plurality of parallel heat transfer tubes within each refrigerant passage, in order to obtain superior performance by balancing and optimizing the characteristics of heat transfer and pressure drop. In these designs, the refrigerant entering an inlet manifold (or so-called inlet manifold) travels through a first multi-tube passage through a width of the heat exchanger to an opposite, typically intermediate manifold. The refrigerant collected in a first intermediate manifold reverses its direction, the tubes are distributed between the heat transfer tubes in the second passage and flows to a second intermediate manifold. This flow pattern can be repeated several times, to achieve optimum performance of the heat exchanger, until the refrigerant reaches an outlet manifold (or so-called outlet manifold). Typically, the individual manifolds are cylindrical in shape (although other shapes are also known in the art) and are represented by different chambers separated by partitions within the same manifold construction set.

Wavy fins are typically placed in the form of parallel heat transfer slats between the heat transfer tubes to improve heat transfer to the outside and obtain a rigid construction. These fins usually connect to the heat transfer tubes during the furnace welding operation. On the other hand, each heat transfer tube preferably contains a plurality of relatively small parallel channels for increasing heat transfer in a tube and for obtaining structural rigidity.

However, there have been some obstacles to the use of parallel flow heat exchangers in a refrigerant system. In particular, a problem, known as poor refrigerant distribution, typically occurs in the microchannel heat exchanger manifolds when the two-phase flow enters the manifold. A vapor phase of the two-phase flow has significantly different properties, it moves to

different speeds and is subjected to different effects of internal and external forces than in a liquid phase. This causes the vapor phase to separate from the liquid phase and flow independently. The separation of the vapor phase and the liquid phase has posed challenges, such as the poor distribution of refrigerant in parallel flow heat exchangers. This phenomenon occurs due to the uneven pressure drop inside the channels and in the inlet and outlet manifolds, as well as a poor design of the distribution system and manifolds. In distributors, the difference in the length of the refrigerant, the severity and the phase separation are the main factors responsible for the poor distribution. Within the heat exchanger channels, variations in heat transfer speed, air flow distribution, manufacturing tolerances and gravity are the key factors. On the other hand, a recent trend of improved performance in heat exchangers has promoted the miniaturization of its channels, which in turn has had a negative impact on the distribution of the refrigerant. Since it is extremely difficult to control all these factors, together with the complexity and inefficiency of the proposed techniques or a prohibitively high cost of the solutions, many of the previous attempts to manage the distribution of the refrigerant have failed.

On the other hand, the poor distribution of the refrigerant can cause degradation of the performance of the total system and the heat exchanger in a wide range of operating conditions. Therefore, it would be desirable to reduce or eliminate poor refrigerant distribution in parallel flow heat exchangers.

EP 0886113 A2 describes a system as set forth in the previous characterizing part of claim 1.

Compendium of the invention

The invention provides a refrigerant system according to claim 1 and a method of operation of a refrigerant system according to claim 14.

In the described embodiments of this invention, one of the phases of the two-phase refrigerant mixture, which is the liquid phase for condensers and the vapor phase for evaporators, is taken from a location within a parallel flow heat exchanger. , in which a liquid phase is likely to separate from a vapor phase and accumulate, causing poor distribution of the refrigerant in downstream heat transfer tubes that are in fluid communication with this location upstream. The refrigerant taken, predominantly in a single phase, which is, once again, liquid for condensers and steam for evaporators, is redirected to a downstream location in a parallel flow heat exchanger, in which the refrigerant is already predominantly in a single phase (the liquid phase for condensers and the vapor phase for evaporators), without going through at least some of the banks (or passages) of downstream heat transfer tubes. Therefore, the rest of the refrigerant predominantly in a single phase (steam for condensers and liquid for evaporators) flowing through the next step of the parallel flow heat exchanger can be evenly distributed between the parallel heat transfer tubes that are placed downstream of the redirection location (or outlet) and are in fluid communication with this location. As a result, the performance of the heat exchanger and the coolant system in total are improved.

In one embodiment, a predominantly one-phase refrigerant is taken from an intermediate manifold and is redirected to another downstream intermediate manifold. In another embodiment, a predominantly single phase refrigerant is taken from an intermediate manifold and redirected to an outlet manifold. Although manifold locations and more convenient bypass and tap return points are preferred, other positions in parallel flow heat exchangers and within the scope of the invention are also feasible. In addition, if, for example, collector locations are used as tap points, a predominantly liquid bypass refrigerant flow in condenser applications is taken from a location near the bottom of the collector of the collector chamber and a flow Coolant bypass predominantly steam in evaporator applications is taken from a location near the top of the manifold or manifold chamber.

On the other hand, in some embodiments, a single phase refrigerant is taken from a single location within a parallel flow heat exchanger, and in other embodiments multiple intake points are used. In addition, although the most feasible is a single bypass return point, space limitations and design can drive multiple bypass return points and are within the scope of the invention.

The bypass line can be placed in the path of the secondary means, such as air, to obtain additional heat transfer and further improve the performance of the heat exchanger and the system as a whole. Also, the bypass line may have internal and external heat transfer enhancement elements to further improve heat transfer between a predominantly single phase bypass refrigerant and a secondary fluid. Since a counterflow arrangement is desired, the bypass line is preferably positioned upstream of the parallel flow heat exchanger for condenser and evaporator applications, with respect to secondary fluid flow.

The invention is applicable to any form and configuration of multi-step parallel flow heat exchanger, with any number of steps and with a general coolant flow direction up or down.

In addition, the invention is beneficial for any parallel flow heat exchanger orientation, even horizontal, vertical and inclined.

In various embodiments, the coolant bypass outlet is arranged by various methods. In some embodiments, there is a hole in a separation plate between the collector chambers that can be controlled by a flotation device (for liquid phase bypass), check valve or solenoid valve. Of course, other control methods known in the art are also applicable and are within the scope of the invention. In other embodiments, a real bypass return line is used to return the refrigerant to a downstream location and a valve can be placed in this bypass return line to control the flow of a bypass refrigerant predominantly in one phase.

As indicated above, the described invention can be implemented in parallel flow heat exchanger installations that function as condensers or as evaporators.

These and other features of the present invention can be better understood from the following specification and drawings, below is a brief description.

Brief description of the drawings

Figure 1 shows a refrigerant system incorporating the present invention.

Figure 2A shows a first scheme.

Figure 2B shows a heat transfer tube design feature.

Figure 3 shows a second scheme.

Figure 4 shows a third scheme.

Figure 5 shows a fourth scheme.

Figure 6 shows a fifth scheme.

Figure 7 shows a sixth scheme.

Detailed description of the preferred embodiments

A basic refrigerant system 20 is illustrated in Figure 1, and includes a compressor 22 that delivers refrigerant in a discharge line 23 directed to a condenser 24. Condenser 24 is a parallel flow heat exchanger, and in a described embodiment It is a microchannel heat exchanger. In condenser 24, heat is transferred from the refrigerant to a secondary fluid, such as air. The high pressure, but not superheated, condensed and typically subcooled refrigerant passes to a liquid line 25 downstream of the condenser 24 and through an expansion device 26, in which it expands at a lower pressure and temperature. Downstream of the expansion device 26, the refrigerant flows through an evaporator 28 and back to the compressor 22. An evaporator 28 can also be a parallel flow heat exchanger. In evaporator 28, heat is transferred from another secondary fluid, such as the air delivered to a conditioned environment, to the environment, to the refrigerant that evaporates and typically overheats during the heat transfer interaction with this secondary fluid . Although a basic refrigerant system 20 is shown in Figure 1, one skilled in the art is well aware that many options and features can be incorporated into a refrigerant system design. All these coolant system configurations are within the scope and can also benefit from the invention. In addition, although all embodiments are described in relation to condenser applications, a person skilled in the art will well understand that a similar approach can be used for evaporators, in which derivation of a predominantly vapor phase (rather than a liquid phase) in condenser applications), which allows the rest of the liquid phase (instead of the vapor phase in condenser applications) to be evenly distributed between the heat transfer tubes downstream.

As shown in Figure 2A, the multi-pass capacitor 24 has a collector structure 30 consisting of multiple chambers 30A, 30B and 30C. An intake manifold chamber 30A receives the refrigerant, typically in the vapor phase, from the discharge line 23. The refrigerant flows to a first bank of parallel heat transfer tubes 32 and then through the condenser core to chamber 34A of an intermediate manifold structure 34. It should be noted that, in practice, there may be more or less refrigerant passages than the four illustrated steps 32, 36, 38 and 40. Furthermore, it should be understood that, although for simplicity reasons each refrigerant pass is represented by single heat transfer tube, typically there are many heat transfer tubes at each step between which the refrigerant is distributed while flowing within the passage, and, in condenser applications, several of the heat transfer tubes within each Bank (or passage) typically decreases in a downstream direction with respect to the flow of refrigerant. For example, there could be 12 heat transfer tubes in the first bank, 8 heat transfer tubes in a second bank, 5 tubes

Heat transfer in a third bank and only 2 heat transfer tubes in the fourth bank. Inside the manifold 34 a separation plate 42 is placed to separate the chamber 34A from the chamber 34B located within the same manifold structure 34.

As shown in Figure 2A, in chamber 34A, the refrigerant is beginning to condense as it flows through the first passage along the tubes 32 (due to the interaction of heat transfer with a secondary fluid) and is found in a two-phase thermodynamic state, although typically with a relatively small amount of liquid in a two-phase mixture. In addition, in this location, the liquid phase may be beginning to separate from the vapor refrigerant, as shown in 35, since the liquid and vapor phases have different thermophysical properties and are affected differently by external forces, such like gravity and pure momentum. The separation of liquid and vapor phases can create poor distribution conditions, while the refrigerant flows from the chamber 34A of the intermediate manifold structure 34 back through the condenser core 24 through a second bank of parallel tubes 36 of heat transfer to chamber 30B of manifold structure 30.

Since, in some cases, a somewhat insignificant amount of coolant accumulates inside chamber 34A, the poor distribution of the coolant cannot have a profound effect on the performance of the condenser 24. However, a float valve 52 is shown. and a discharge orifice 50 for discharging liquid refrigerant into the adjacent chamber 34B, without passing through the second and third bank of heat transfer tubes 36 and 38 respectively, which are downstream. As a result, favorable conditions are created for a uniform distribution of a refrigerant predominantly in a single vapor phase between the second bank of heat transfer tubes 36. The refrigerant entering the second bank of heat transfer tubes 36 is predominantly in a vapor phase and flows in a direction generally in parallel (although counterflow) to the refrigerant flow in the first bank of heat transfer tubes 32. As shown in Figure 2A, a separation plate 42 prevents the refrigerant Flow communication is mixed or directed between collector chambers 30A and 30B. In chamber 30B, the refrigerant is also in a two-phase thermodynamic state but contains lower vapor quality and potentially promotes the conditions for the accumulation of liquid refrigerant, as shown in 144, at the bottom of chamber 30B.

In such circumstances, the vapor refrigerant will flow predominantly to the top of the heat transfer tubes of the third step 38 and the liquid refrigerant flows through the bottom of the third bank 38 of heat transfer tubes. Therefore, the poor distribution of the refrigerant can have a profound effect on the performance of the condenser 24. Another float valve assembly 52 and drain hole 50 discharges the liquid refrigerant downstream to the adjacent chamber 30C, without passing through the third and fourth bank of heat transfer tubes 38 and 40 respectively. Accordingly, uniform distribution of a predominantly single phase vapor refrigerant between the third bank of heat transfer tubes 38 can be achieved.

The refrigerant predominantly in a single vapor phase flows, for additional condensation, from the intermediate chamber 30B of the collector structure 30 to a third bank of parallel heat transfer tubes 38 generally located in an arrangement parallel to the first and second bank of heat transfer tubes 32 and 36, through condenser 24 and to an intermediate chamber 34B of manifold structure 34. The level of liquid refrigerant in the collector chamber 34B, as shown in 244, can be even higher than levels 35 and 144, since the liquid refrigerant from the intermediate manifold chamber 34A enters directly into the manifold chamber 34B through hole 50. It should be understood that liquid levels 35, 144 and 244 may be somewhat exaggerated to illustrate the concept of the present invention, as well as that they may vary with environmental and operating conditions.

The refrigerant flowing through the chamber 34B has even lower steam quality and potentially creates similar conditions of poor distribution for the fourth (and last) bank of heat transfer tubes 40. Again, the hole 50 in the plate of separation 42 placed between the chambers 30B and 30C allows the refrigerant flow to enter from the intermediate manifold chamber 30B into the intermediate manifold chamber 30C and mix with the refrigerant flow left by the fourth bank of heat transfer tubes 40 , while float valve 52 prevents steam refrigerant from flowing between the same chambers.

From the chamber 30C, the liquid refrigerant leaves the condenser 24 through line 25. As is known, corrugated fins 33, and typically as parallel sheets, are located and connected to the heat transfer tubes (typically during a process furnace welding) to extend the heat transfer surface and improve the structural rigidity of the condenser 24.

As shown in Figure 2B, the heat transfer tubes within the banks 32, 36, 38 and 40 of tubes may consist of a plurality of parallel channels 100 separated by walls 101. Figure 2B is a cross-sectional view of the heat transfer tubes shown in Figure 2A. Channels 100 allow better heat transfer characteristics and help better structural rigidity. The cross section of the channels 100 may take different forms, and although illustrated as a rectangle in Figure 2B, it may have, for example, triangular, circular or trapezoidal configurations.

In the present invention, the liquid refrigerant is taken from the liquid accumulation locations within the two-phase flow part of the condenser 24 (which may or may not be directly related to the separation plates 42 that divide the collector chambers) and it goes to the downstream locations where a liquid refrigerant is flowing predominantly in a single phase, thus not passing through the region in which the refrigerant is present in two phases and avoiding poor distribution conditions for the bank of downstream heat transfer tubes. Therefore, the performance of the parallel flow heat exchanger and the coolant system as a whole are improved. As an alternative, a smaller size heat exchanger can be allowed if an improvement in performance is not required.

Although the float valve 52 is illustrated as having a spherical shape, it can also have other configurations, such as conical, cylindrical, etc. In addition, other types of valves can be used instead, such as an electrovalve or a check valve. Although an internal bypass between the collector chambers is convenient, it is not always feasible (e.g., when the collector chambers are placed at opposite ends of the heat exchanger) or desirable from a manufacturing complexity point of view. . In such circumstances, an external branch can be established instead, such as a branch line 53 that takes liquid refrigerant from a location 244 near the bottom of the manifold chamber 34B to a downstream location 54 inside the chamber 30C outlet manifold. In the collector outlet chamber 30C, the three flows of liquid refrigerant are mixed (which leaves the fourth bank of heat transfer tubes 40, derived from chamber 30B to chamber 30C and derived from chamber 34B to chamber 30C). A flow control device, such as the valve 49, can be placed on the branch line 53, and is associated with a control 10 to allow the flow of this liquid refrigerant to be pulsed, modulated or cut completely. In this way, a refrigerant system designer can achieve additional precise control over the desired amount of liquid refrigerant flow derived, which can be adapted, for example, to specific operating conditions, to offer even more uniform distribution of the phases liquid and vapor refrigerant between heat transfer tubes. Similarly, in case the flotation valves 52 are replaced by solenoid valves, a similar type of control can be exercised for these valves. In addition, level measuring devices installed with the liquid refrigerant flow control devices can be placed in the collector chambers, if desired or if necessary for proper operation of these liquid refrigerant flow control devices. Finally, other locations, instead of the intermediate collector chambers, can be selected for the intake of the liquid refrigerant.

The branch line 53 may have internal and external heat transfer improvement elements and are placed in the path of the secondary means, such as air, flowing through the condenser 24. In addition, in order to maintain the total backflow configuration, the bypass line 53 is preferably placed upstream of the heat transfer condenser 24, relative to the air flow.

Figure 3 shows another embodiment 124 of the parallel flow condenser having three passages and inlet and outlet tubes 23 and 153 respectively located on opposite sides of the heat exchanger core, where a hole of a predetermined size 54 replaces the assembly of float valve 52 and orifice 50 of the first intermediate manifold chamber 34A shown in Figure 2A. The size of the hole 54 must be selected to maintain a liquid seal between the intermediate manifold chambers 34A and 34B in all operating conditions. Similar to the embodiment of Figure 2A, an orifice assembly 50 and float valve 52 is included to pass the liquid refrigerant from an intermediate manifold chamber 30B to a bypass return line 56 and back to a location 51 and to an outlet tube 153. In all other aspects the embodiment of Figure 3 is similar to the embodiment of Figure 2 A.

Figure 4 shows yet another embodiment 224 of a parallel flow condenser having two passages, wherein a single bypass return line 53 redirects the predominantly liquid refrigerant from an intermediate manifold 34 to a downstream point 160 and to a chamber 30B of outlet manifold, to be combined with the refrigerant leaving a second bank of heat transfer tubes 36. In all other aspects the embodiment of Figure 4 is similar to the embodiment of Figure 2 A.

Figure 5 shows another embodiment 324 of a parallel flow condenser having four passages, wherein bypass return lines 58 and 62 redirect predominantly liquid refrigerant from an intermediate manifold chamber 30B to an outlet tube 25 and from a intermediate manifold chamber 34B to a manifold outlet chamber 30C, respectively, or to locations 60 and 64 where a predominantly single liquid phase refrigerant is already present. Again, in the absence of active flow control devices associated with the bypass lines, maintaining a liquid seal in all operating conditions is essential. In this embodiment, the flow of refrigerant is generally upward but in all other aspects it is similar to the embodiment of Figure 2A.

Figure 6 shows yet another embodiment 424 of the parallel flow condenser having three coolant passages, collector inlet and outlet chambers on opposite sides of the condenser core and generally a coolant direction, upwards, where a bypass return line 62 to redirect the liquid refrigerant from a manifold intermediate chamber 30B to a manifold outlet chamber 34B. Again, in all operating conditions the maintenance of a liquid seal is critical. In addition, in the two embodiments of Figures 5 and 6, in which the flow of refrigerant is generally towards 6 10

above, the pressure drop across the omitted bank of heat transfer tubes (for example, the bench 40 in the embodiment of Figure 5 and the bench 38 in the embodiment of Figure 6) must be smaller than the drop in pressure through the bypass return duct 58 plus the hydrostatic height between the chambers 30B and 30C in the embodiment of Figure 5 and through the bypass return line 62 plus the hydrostatic height between the chambers 30B and 34B in the embodiment of Figure 6.

Figure 7 shows another embodiment 524 of a parallel flow condenser having two steps in which a bypass return line 70 leads to a point 68 in the manifold outlet chamber 30A in which it is mixed with the refrigerant leaving of the second bank of heat transfer tubes 36, and includes a float valve 80 and a hole 66. In all other aspects, this embodiment is similar to the embodiments of Figure 5 and Figure 6.

As a summary, in the present invention, one of the phases of the two-phase refrigerant mixture, which is the liquid phase for the condensers and the vapor phase for the evaporators, is taken from a location within a heat exchanger of parallel flow, in which a liquid phase is likely to separate from a vapor phase and accumulate, causing poor distribution of the refrigerant in downstream heat transfer tubes that are in fluid communication with this location upstream. The refrigerant taken, predominantly in a single phase, (once again, liquid for condensers and steam for evaporators) is redirected to a downstream location in a parallel flow heat exchanger, in which the refrigerant is already predominantly in a single phase (the liquid phase for condensers and the vapor phase for evaporators), without going through at least some of the banks (or passages) of downstream heat transfer tubes. Therefore, the rest of the refrigerant predominantly in a single phase (steam for condensers and liquid for evaporators) flowing through the next step of the parallel flow heat exchanger can be evenly distributed between the parallel heat transfer tubes that are placed downstream of the redirection location (or outlet) and are in fluid communication with this location. As a result, the performance of the heat exchanger and the coolant system in total are improved.

A predominantly single phase refrigerant is taken from an intermediate manifold and redirected to another downstream intermediate manifold, or to an outlet manifold, or to a refrigerant outlet line. Although the most convenient collector locations and bypass and tap return points are preferred, other positions in parallel flow heat exchangers and within the scope of the invention are also feasible. The redirection method may be internal to the heat exchanger design, such as redirection through the plates separating the collector chambers, or external, such as by bypass coolant lines. Active flow control devices, such as flotation valves or solenoid valves, passive bypass devices, such as orifices or check valves can be used.

On the other hand, a single-phase refrigerant can be taken from a single location within a parallel flow or multi-point heat exchanger. In addition, although the most feasible is a single bypass return point, space limitations and design can drive multiple bypass return points and are within the scope of the invention.

It should be noted that the bypass line can be placed in the path of the secondary means, such as air, to obtain an additional heat transfer and further improve the performance of the heat exchanger and the system as a whole. The bypass line may have internal and external heat transfer enhancement elements to further improve heat transfer between a predominantly single phase bypass refrigerant and a secondary fluid. Since a counterflow arrangement is desired, the bypass line is preferably positioned upstream of the core of the parallel flow heat exchanger for condenser and evaporator applications, with respect to secondary fluid flow.

The invention is applicable to any form and configuration of multi-step parallel flow heat exchanger, with any number of steps and with a general coolant flow direction up or down. In an upward condenser configuration, the pressure drop through the bypass return line and the hydrostatic height must not exceed the pressure drop through the bypass tube bank for the desired amount of bypass refrigerant flow. Also, in many cases, as indicated above, in the absence of active flow control devices a good liquid seal is important for proper operation and functionality. In addition, the invention is beneficial for any parallel flow heat exchanger orientation, even horizontal, vertical and inclined.

The refrigerant taken in a single phase can be actively controlled to maintain the liquid seal to improve the functionality or adjust the thermodynamic conditions of the refrigerant at the heat exchanger outlet. In addition, sensors, such as a liquid level sensor, can be used in conjunction with these flow control devices. While the main subject of the invention focuses on condenser applications, refrigerant system evaporators can also benefit from the invention. In evaporator applications, a predominantly single-phase vapor refrigerant is derived around some of the banks of heat transfer tubes (instead of liquid in condenser applications). In addition, if, for example, collector locations are used as intake points, a predominantly steam bypass flow must be taken for evaporator applications from the location near the top of the collector or collector chamber (in applications condenser should be taken predominantly liquid bypass flow from the location near the bottom of the collector or collector chamber). In most other aspects, the concept of the invention is similar for condenser and evaporator applications.

Although the invention is described for parallel flow heat exchangers, it has applications for other types of heat exchangers, for example, for heat exchangers having intermediate collectors in condenser applications. In addition, the number of steps shown is purely exemplary and a heat exchanger with any number of steps can also benefit from the present invention. In addition, the collector constructions 30 and 34 covering a series of cameras can have different shapes and

10 design settings. In addition, the collector chambers cannot necessarily be placed within the same collector construction.

Although a preferred embodiment of this invention has been described, one skilled in the art will recognize that certain modifications fall within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.

Claims (12)

1. A refrigerant system (20) comprising: a capacitor (24; 124; 224; 324; 424; 524); a compressor (22); an expansion device (26); Y an evaporator (28), the compressor to deliver a compressed refrigerant to the condenser, the refrigerant of said condenser passes through the expansion device, and from said expansion device through the evaporator, and from said evaporator is returned to said compressor; Y at least said condenser or said evaporator having a plurality of heat transfer tubes (32, 36, 38, 40) that pass a refrigerant downstream in a generally parallel manner; Y at least one location (30B, 34A, 34B, 34) within said evaporator (28) that is likely to receive separate phases of vapor and coolant mixture when the coolant flows through the plurality of transfer tubes of heat, characterized in that at least a part of the separated vapor phase is taken from said location and delivered to a downstream location (30C, 34B; 30; 25) without going through at least some of the transfer tubes of heat to improve the distribution of a remaining refrigerant flowing through the omitted heat transfer tubes that are in direct fluid communication with this location.

2.

The refrigerant system (20) as set forth in claim 1, comprising

at least one location (30B, 34A, 34B, 34) within said condenser that is likely to receive separate phases of vapor and coolant mixture when the coolant flows through the plurality of heat transfer tubes, and at least a part of the liquid phase is taken from said location and delivered to a downstream location (30C, 34B; 30; 25) without going through at least some of the heat transfer tubes to improve the distribution of a remaining refrigerant that flows through the omitted heat transfer tubes that are in direct fluid communication with this location.

3.

The refrigerant system (20) as set forth in claim 1 or 2, wherein said at least one of said condenser (24; 124; 224; 324; 424; 524) and said evaporator (28) has at least one manifold structure (30, 34) in fluid communication with said plurality of heat transfer tubes (32, 36, 38, 40), said at least one manifold structure is provided with at least one member of separation that provides at least two cameras (30A, 30B, 30C, 34A, 34B) within said at least one distributor structure and at least one of said cameras is said socket location.

Four.

The refrigerant system (20) as set forth in claim 3, wherein said separation member is one of a separation plate (42), a check valve, a float valve (52; 80), a solenoid valve, a hole with a liquid seal and a combination thereof.

5.

The refrigerant system (20) as set forth in claim 1 or 2, wherein said at least one of said condenser (24; 124; 224; 324; 424; 524) and said evaporator (28) has at least one manifold structure (30, 34) in fluid communication with said plurality of heat transfer tubes (32, 36, 38, 40), said at least one manifold structure is provided with at least one member of separation that provides at least two chambers (30A, 30B, 30C, 34A, 34B) within said at least one distributor structure and at least one of said chambers is said downstream location (30C, 34B; 30; 25).

6.

The refrigerant system (20) as set forth in claim 1 or 2, wherein said at least one of said condenser (24; 124; 224; 324; 424; 524) and said evaporator (28) has a coolant outlet tube (25) and said coolant outlet tube is said downstream location (30C; 34B; 30; 25).

7.

The refrigerant system (20) as set forth in any preceding claim, wherein said separated refrigerant is carried at least partially by a branch line (53; 56; 62; 78).

8.

The refrigerant system (20) as set forth in claim 7, wherein said bypass line (53; 56; 62; 78) has at least internal or external heat transfer enhancement elements.

9.

The refrigerant system (20) as set forth in claim 7, wherein said bypass line (53; 56; 62; 78) associated at least with said condenser (24; 124; 224; 324; 424; 524 ) or with said evaporator (28) is placed in the air flow path that moves over at least said condenser

or said evaporator. 9 10. The refrigerant system (20) as set forth in claim 9, wherein said bypass line (53; 56; 62; 78) associated at least with said condenser (24; 124; 224; 324; 424 ; 524) or with said evaporator (28) is placed upstream of at least said condenser or said evaporator, with respect to the air flow. The refrigerant system (20) as set forth in any preceding claim, wherein each of said plurality of heat transfer tubes (32, 36, 38, 40) has a plurality of small channels (100) parallel internals carrying refrigerant in parallel paths within said heat transfer tubes, and wherein said parallel internal channels create a heat transfer microchannel tube or heat transfer minichannel tube. 10 12. The refrigerant system (20) as set forth in any preceding claim, wherein there are multiple locations with intakes.

13.

The refrigerant system (20) as set forth in any preceding claim, wherein there are multiple downstream locations.

14.

A method of operation of a refrigerant system comprising the steps of:

15 (1) providing a compressor (22) to deliver a compressed refrigerant to a condenser (24; 124; 224; 324; 424; 524), the refrigerant of said condenser passes through an expansion device (26), and from said expansion device through an evaporator (28) and from said evaporator it is returned to said compressor; Y (2) provide at least said condenser or said evaporator having a plurality of tubes of 20 heat transfer (32, 36, 38, 40) that pass a refrigerant downstream in a generally parallel manner; characterized by the stage of: (3) identify at least one location (34A, 34B, 30B, 34) within said evaporator (28) that is likely to receive separate phases of vapor and coolant mixture when the coolant flows to 25 through the plurality of heat transfer tubes, and at least a part of the vapor phase is taken from said location and delivered to a downstream location (30C, 34B; 30; 25) without passing at least by some of the heat transfer tubes to improve the distribution of a remaining refrigerant flowing through the omitted heat transfer tubes that are in direct fluid communication with this location. 15. The method as set forth in claim 14, comprising the step of (4) identifying at least one location (34A, 34B, 30B, 34) within said condenser (24; 124; 224; 324; 424; 524) is likely to receive separate phases of vapor and coolant mixture when the refrigerant flows through the plurality of heat transfer tubes, and at least a part of the separated liquid phase is taken from said location and delivered to a downstream location (30C, 34B; 30; 35 25) without going through at least some of the heat transfer tubes to improve the distribution of a remaining refrigerant flowing through the omitted heat transfer tubes that are in direct fluid communication with this location.