HEAT EXCHANGER REFRIGERANT DRAIN

Abstract

A combination refrigeration displacement and drain device is disclosed that can be mounted within a heat exchanger, such as a shell and tube heat exchanger, which may be used for example as a heat exchanger in a chiller unit, which may be used in an HVAC or refrigeration system. One example of such components can include heat exchangers, such as for example a condenser employing a gravity drain. Advantageously, the combination refrigeration displacement and drain device herein can provide a refrigerant charge reduction for example that is used in the chiller unit, while facilitating drainage out of the heat exchanger. The combination refrigeration displacement and drain device can alleviate the liquid refrigerant accumulation that may normally be necessary to induce flow in a gravity drain design.

Description

FIELD

This disclosure relates generally to a heat exchanger refrigerant drain, such as in gravity draining of refrigerant in a heat exchanger. In particular, the heat exchanger drain can be in a shell and tube heat exchanger, for example a condenser, which may be used in a chiller unit of a heating, ventilation, and air conditioning (HVAC) system or refrigeration system. In particular, apparatuses, systems, and methods are directed a refrigerant drain channel which displaces available volume in a shell of the heat exchanger, e.g. the condenser, to efficiently use and/or even reduce amount of refrigerant used in a chiller unit.

BACKGROUND

Refrigerants are used in HVAC systems such as, for example, in a chiller unit. Some heat exchangers in chiller units employ gravity drain type systems for the refrigerant circulating into and out of the heat exchanger.

SUMMARY

Certain refrigerants, such as, for example, hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), are being or have been phased out due to increasing standards to reduce ozone depletion. The use of relatively expensive refrigerants are being looked at as alternatives to meet such changing standards. Use of such relatively expensive refrigerants may be a concern when considering factors as larger capacity cooling systems, e.g., chiller units of an HVAC system, are being designed to meet for example growing comfort cooling or air-conditioning demands. Reducing refrigerant charge in such systems would be advantageous while still meeting such environmental standards and market demands on higher capacity units.

One example where such charge minimization may be available is in a condenser heat exchanger in a shell and tube design used in a chiller unit. In HVAC chillers, as one example, the condenser is the heat exchanger wherein the heat is rejected by the chiller to a second fluid system. The refrigerant within the condenser undergoes a phase change from vapor to liquid. In shell and tube condensers, the condensed liquid refrigerant can cascade from the tubes to the bottom of the shell, such as in a falling film or a gravity drain configuration. For example, one method of extracting the liquid refrigerant is using a gravity drain design where liquid accumulates until, for example, a sufficient liquid head is equivalent to the velocity head and head losses to induce flow toward a drain connection located axially along the shell length. However, in previous designs, a significant amount of liquid refrigerant charge can accumulate on the bottom of the condenser, e.g., the shell of the condenser.

Improvements may be made to such shell and tube heat exchangers, for example condensers.

Embodiments illustrated and described herein are directed to a combination refrigeration displacement and drain device that can be mounted within a heat exchanger, such as a shell and tube heat exchanger, which may be used, for example, as a heat exchanger in a chiller unit, which may be used in an HVAC or refrigeration system. One example of such components can include heat exchangers, such as, for example, a condenser employing a gravity drain, e.g., falling film type heat exchanger in a shell and tube construction. It will be appreciated that the combination refrigeration displacement and drain device herein can be implemented in various types of chillers using various types of compressors, such as, for example, a centrifugal compressor, and can be applied in various types of heat exchangers of various sized lengths and/or diameters of the shell, and where refrigerant charge may be accumulating.

Advantageously, the combination refrigeration displacement and drain device herein can provide a refrigerant charge reduction, for example, that is used in the chiller unit, while facilitating drainage out of the heat exchanger. The combination refrigeration displacement and drain device can alleviate the liquid refrigerant accumulation that may normally be necessary to induce flow in a gravity drain design. The combination refrigeration displacement and drain device generally has one or more slants and one or more channels that are inclined and decline in the direction of a drain outlet or connection of the heat exchanger. It will be appreciated that the combination refrigeration displacement and drain device can be configured, designed, and/or optimized to account for relative velocity profiles across any section of the shell and locations at which the combination refrigeration displacement and drain device may reside. Such configuration, design, and/or optimization, whether such velocity profiles are uniform or not uniform within the shell, can be determined. Energy equations such as Bernoulli equations, derivatives and variants thereof, which are known, can be used to analyze and determine flow profiles that may be desired and/or necessary, while considering factors such as liquid head, velocity head, head losses, hydrostatic head, and specific structure of the slant(s) and channel(s) (e.g., friction slope(s)) of the combination refrigeration displacement and drain device.

In one embodiment, a heat exchanger includes a shell with a volume therein. The shell includes an inlet for a heat exchange fluid, such as for example a vapor inlet for refrigerant vapor to enter the shell, and includes an outlet which can have a drain connection. The outlet is for fluids containing predominantly liquid (e.g., liquid refrigerant that has undergone a heat exchange with the fluid on the tube side (e.g., water running through the tubes)) to drain from the shell. Heat exchange tubes that may be configured to carry a process fluid, such as, for example, water, along substantially the length of the shell. The tubes reside in the volume of the shell at around a relatively middle height and upward toward the top at about relatively higher height. A combination refrigeration displacement and drain device resides within the shell, and is located and/or positioned toward relatively a lower height of the shell. The combination refrigeration displacement and drain device has a structure, arrangement, and/or configuration to displace or prevent refrigerant from collecting at portions on the bottom of the shell, and to induce flow toward the outlet.

In some embodiments, the combination refrigeration displacement and drain device has one or more slanted portions. In some embodiments, the slanted portions extend along the length of the shell and decline from the shell wall toward a bottom of the shell. In some embodiments, the slanted portions decline from an end of the shell along one or more portions of the length of the shell.

In some embodiments, the slanted portions provide displacement which displaces, blocks, and/or does not allow the heat exchange fluid, e.g. refrigerant, to collect or otherwise accumulate on wall(s) at the bottom of the shell.

In some embodiments, the heat exchanger is a condenser.

In some embodiments, the heat exchanger can be used in a chiller unit.

In some embodiments, the chiller unit is used in an HVAC system.

Advantageously, liquid head required to induce flow in a gravity type drain, which may otherwise be needed without the use of the combination refrigeration displacement and drain device, can be displaced by the use of the combination refrigeration displacement and drain device to facilitate flow. For example, in a full load operating condition, which is the same condition where optimal charge may be determined. The combination refrigeration displacement and drain device can be configured, designed, and/or optimized, such that displaced refrigerant volume can be closely and/or directly correlated to a reduction in refrigerant charge such as in a chiller unit. Dependent, for example, on spatial constraints of the chiller unit or the heat exchanger, the combination refrigeration displacement and drain device may reduce as much as 50% to 75% of the liquid refrigerant charge, as compared to some designs primarily or only relying on gravity drain, e.g., velocity head of the liquid, within the shell.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the will become better understood when the following detailed description is read with reference to the accompanying drawings, wherein:

FIG. 1 is side schematic view of one embodiment of a heat exchanger with a combination refrigerant displacement and drain device within the shell of the heat exchanger.

FIG. 2 is a sectional or end view of the heat exchanger of FIG. 1.

FIG. 3 is a perspective view showing a part of a shell and tube heat exchanger showing part of the shell and part of an embodiment of a combination refrigerant displacement and drain device.

FIG. 4 is a perspective view showing a part of a shell and tube heat exchanger showing part of the shell and part of an embodiment of a combination refrigerant displacement and drain device.

FIG. 5 is a perspective view showing a part of a shell and tube heat exchanger showing part of the shell and part of an embodiment of a combination refrigerant displacement and drain device.

FIG. 6 is a perspective view showing a part of a shell and tube heat exchanger showing part of the shell and part of an embodiment of a combination refrigerant displacement and drain device.

FIG. 7 is a perspective view showing a part of a shell and tube heat exchanger showing part of the shell and part of an embodiment of a combination refrigerant displacement and drain device.

FIG. 8 is a perspective view showing a part of a shell and tube heat exchanger showing part of the shell and part of an embodiment of a combination refrigerant displacement and drain device.

FIG. 9 is a perspective view showing a part of a shell and tube heat exchanger showing part of the shell and part of an embodiment of a combination refrigerant displacement and drain device.

FIG. 10 is a partial sectional view showing the combination refrigerant displacement and drain device of FIG. 9.

FIG. 11 is a perspective view showing a part of a shell and tube heat exchanger showing part of the shell and part of an embodiment of a combination refrigerant displacement and drain device.

FIG. 12 is a partial sectional view showing the combination refrigerant displacement and drain device of FIG. 9.

FIG. 13 is a perspective view showing a part of a shell and tube heat exchanger showing part of the shell and part of an embodiment of a combination refrigerant displacement and drain device.

FIG. 14 is a partial end view showing the combination refrigerant displacement and drain device of FIG. 13.

While the above-identified figures set forth particular embodiments of the combination refrigerant displacement and drain device in a shell and tube heat exchanger, other embodiments are also contemplated, as noted in the descriptions herein. In all cases, this disclosure presents illustrated embodiments of the combination refrigerant displacement and drain device by way of representation but not limitation. Numerous other modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of the combination refrigerant displacement and drain device described and illustrated herein.

DETAILED DESCRIPTION

Embodiments disclosed herein relate generally to a heat exchanger refrigerant drain, such as in gravity draining of refrigerant in a heat exchanger. In particular, the heat exchanger drain can be in a shell and tube heat exchanger, for example a condenser, which may be used in a chiller unit of a heating, ventilation, and air conditioning (HVAC) system or refrigeration system. In particular, apparatuses, systems, and methods are directed a refrigerant drain channel which displaces available volume in a shell of the heat exchanger, e.g. the condenser, to efficiently use and/or even reduce amount of refrigerant used in a chiller unit.

The combination refrigeration displacement and drain device generally has one or more slants (e.g., ramps, ramp portions) and one or more channels that are inclined and decline in the direction of a drain outlet or connection of the heat exchanger. It will be appreciated that the combination refrigeration displacement and drain device can be configured, designed, and/or optimized to account for relative velocity profiles across any section of the shell and locations at which the combination refrigeration displacement and drain device may reside. Such configuration, design, and/or optimization, whether such velocity profiles are uniform or not uniform within the shell, can be determined. Energy equations such as Bernoulli equations, derivatives and variants thereof, which are known, can be used to analyze and determine flow profiles that may be desired and/or necessary, while considering factors such as liquid head, velocity head, head losses, hydrostatic head, and specific structure of the slant(s) and channel(s) (e.g., friction slope(s)) of the combination refrigeration displacement and drain device.

FIG. 1 is side schematic view of one embodiment of a heat exchanger 10 with a combination refrigerant displacement and drain device 30 within a shell 16 of the heat exchanger 10, according to an embodiment. The heat exchanger 10 has an inlet 12 and an outlet 14. Heat exchange tubes 22 run substantially the length L of the shell 16 and between the tubesheets 20. The combination refrigerant displacement and drain device 30 has one or more slanted portions 32 or slants that direct and/or induce fluid flow, e.g., liquid flow, to the outlet 14. The combination refrigerant displacement and drain device 30 separates the volume inside the shell 16 which displaces portions of the volume inside the shell 16 and proximate or toward a bottom 18 of the shell 16.

FIG. 2 is a sectional or end view of the heat exchanger 10 of FIG. 1, according to an embodiment. FIG. 2 shows the combination refrigerant displacement and drain device 30 slanting downward relative to the drawing view.

FIGS. 3 to 14 show additional embodiments for a combination refrigerant displacement and drain device, e.g., the combination refrigerant displacement and drain device 30 of FIGS. 1-2, and which are specifically described below. While bottom quarter perspective views are shown for the embodiments of FIGS. 3 to 14, it will be appreciated that structures based on the mirror images of what is shown can be achieved at any of the other bottom three quarters of the heat exchange shell to complete the view.

FIG. 3 is a perspective view showing a part of a shell and tube heat exchanger showing part of a shell 306 and outlet 304, and part of an embodiment of a combination refrigerant displacement and drain device 300. The combination refrigerant displacement and drain device 300 has slants 302 which slant down toward a bottom of the shell 306 and also slant from an end toward the outlet 304. The slants 302 converge forming a channel(s) 308.

FIG. 4 is a perspective view showing a part of a shell and tube heat exchanger showing part of a shell 406 and outlet 404 and part of an embodiment of a combination refrigerant displacement and drain device 400. The combination refrigerant displacement and drain device 400 has slants 402 which slant down toward a bottom of the shell 406 and also slant from an end toward the outlet 404. The slants 402 converge forming a channel(s) 408 which meets up with the outlet 404.

FIG. 5 is a perspective view showing a part of a shell and tube heat exchanger showing part of a shell 506 and outlet 504 and part of an embodiment of a combination refrigerant displacement and drain device 500. The combination refrigerant displacement and drain device 500 has slants 502 which slant down toward a bottom of the shell 506 and also slant from an end toward the outlet 504. The slants 502 converge forming a channel(s) 508. The device 500 can also include a modified sump area 510, which is in fluid communication with the channel 510 and the outlet 504, where the sump 510 forms a step or intermediate region to induce fluid flow.

FIG. 6 is a perspective view showing a part of a shell and tube heat exchanger showing part of a shell 606 and outlet 604 and part of an embodiment of a combination refrigerant displacement and drain device 600. The combination refrigerant displacement and drain device 600 has slants 602 which slant down toward a bottom of the shell 606 and also slant from an end toward the outlet 604. The slants 602 converge forming a channel(s) 608, which can meet with the outlet 604. The channel 608 at a portion proximate the outlet can be “clipped” or shaped to provide a slanted edge to help induce flow.

FIG. 7 is a perspective view showing a part of a shell and tube heat exchanger showing part of a shell 706 and an outlet 704 and part of an embodiment of a combination refrigerant displacement and drain device 700. The combination refrigerant displacement and drain device 700 has slants 702 which slant down toward a bottom of the shell 706 and also slant from an end toward the outlet 704. As shown there are multiple discreet or separate slants 702 which may have tapered edge to form separate channels 708.

FIG. 8 is a perspective view showing a part of a shell and tube heat exchanger showing part of a shell 806 and outlet 804 and part of an embodiment of a combination refrigerant displacement and drain device 800. The combination refrigerant displacement and drain device 800 has slants 802 which slant down toward a bottom of the shell 806 and also slant from an end toward the outlet 804. As shown there are multiple discreet or separate slants 802 which may have tapered edge to form separate channels 808 and which may taper toward the center to form additional channels.

FIG. 9 is a perspective view showing a part of a shell and tube heat exchanger showing part of a shell 906 and an outlet 904 and part of an embodiment of a combination refrigerant displacement and drain device 900. The combination refrigerant displacement and drain device 900 has a slant 902 which slant which may also include a curvature portion down toward a bottom of the shell 906 and also slant from an end toward the outlet 904. The slant 902 can converge forming a channel(s) 908. The slant 902 also can include a displacer wall. FIG. 10 is a partial sectional view showing the combination refrigerant displacement and drain device 900 of FIG. 9.

FIG. 11 is a perspective view showing a part of a shell and tube heat exchanger showing part of a shell 1106 and an outlet 1104 and part of an embodiment of a combination refrigerant displacement and drain device 1100. The combination refrigerant displacement and drain device 1100 has a slant 1102 which slants down toward a bottom of the shell 1106 and also slants from an end toward the outlet 1104. The slant 1102 can converges forming a channel(s) 1108. The slant 1102 also can include be a displacer wall. FIG. 12 is a partial sectional view showing the combination refrigerant displacement and drain device 1100 of FIG. 9.

FIG. 13 is a perspective view showing a part of a shell and tube heat exchanger showing part of a shell 1306 and the outlet 1304 and part of an embodiment of a combination refrigerant displacement and drain device 1300. The combination refrigerant displacement and drain device 1300 has slants 1302 which slant down toward a bottom of the shell 1306 and also slant from an end toward the outlet 1304. The slants 1302 converge forming a channel(s) 1308. The channel 1308 can include a trough section, such as a central trough, which can help induce flow. FIG. 14 is a partial end view showing the combination refrigerant displacement and drain device 1300 of FIG. 13.

With regard to the forgoing description, it is to be understood that changes may be made in detail, without departing from the scope of the present invention. It is intended that the specification and depicted embodiments are to be considered exemplary only, with a true scope and spirit of the invention being indicated by the broad meaning of the claims.

Claims

1-20. (canceled)

21. A heating, ventilation, and air conditioning (HVAC) system, comprising: a compressor, a condenser, an expander, and an evaporator,the compressor, the condenser, the expander, and the evaporator are fluidly connected,the condenser is configured to condense vapor refrigerant received from the compressor to liquid refrigerant,the condenser comprising: a shell having a volume, a length, a first end, a second end, a refrigerant inlet, and a refrigerant outlet, the shell being cylindrical, the refrigerant inlet being disposed at a relatively higher vertical elevation of the shell than the refrigerant outlet such that gravitational force induces flow of refrigerant from the refrigerant inlet toward the refrigerant outlet, the length of the shell extending from the first end to the second end in a longitudinal direction, the refrigerant outlet being disposed in the middle of the shell along the longitudinal direction;heat exchanger tubes extending in the longitudinal direction of the shell between tubesheets; anda combination refrigerant displacement and drain device disposed within the shell and separating the volume inside the shell, the combination refrigerant displacement and drain device comprising:a plurality of slants which slant from a first vertical elevation in the shell toward a second vertical elevation in the shell, the second vertical elevation being relatively closer to a bottom cylindrical part of the shell, the plurality of slants extending and slanting toward the refrigerant outlet in the longitudinal direction, wherein the plurality of slants converge to form a channel, the channel extending a length of one of the plurality of slants, and the channel adapted to guide the refrigerant toward the refrigerant outlet,wherein the combination refrigerant displacement and drain device is configured to prevent refrigerant from collecting and accumulating in the volume of the shell which is between the combination refrigerant displacement and drain device and the bottom cylindrical part of the shell,wherein the combination refrigerant displacement and drain device displaces a portion of the volume of the shell, which is between the combination refrigerant displacement and drain device and the bottom cylindrical part of the shell, the portion being a displaced refrigerant volume,wherein the heat exchanger tubes are disposed at a vertical elevation that is relatively closer to the refrigerant inlet than the combination refrigerant displacement and drain device,wherein in operation, the flow of refrigerant is directed into the shell of the condenser via the refrigerant inlet, such that the combination refrigerant displacement and drain device is configured to direct the flow of refrigerant out of the shell to the expander via the refrigerant outlet, the flow of refrigerant is then directed from the expander to the evaporator, the flow of refrigerant is then directed from the evaporator to the compressor, and the flow of refrigerant is then directed from the compressor back into the shell of the condenser via the refrigerant inlet.

22. The HVAC system according to claim 21, wherein the plurality of slants extend continuously along a length of the shell.

23. The HVAC system according to claim 22, wherein the plurality of slants is designed based on a relative velocity profile of the refrigerant in the shell.

24. The HVAC system according to claim 21, wherein the plurality of slants converge to form a plurality of channels.

25. The HVAC system according to claim 21, wherein the plurality of slants extend continuously from an end of the shell toward the refrigerant outlet.

26. The HVAC system according to claim 21, further comprising a sump area disposed in fluid communication with the channel and the refrigerant outlet, the sump area being disposed between the channel and the refrigerant outlet.

27. The HVAC system according to claim 21, wherein a first end of the plurality of slants at the first vertical elevation is disposed at an end of the shell that is opposite the refrigerant outlet, and a second end of the plurality of slants at the second vertical elevation is disposed relatively closer to the refrigerant outlet.

28. The HVAC system according to claim 21, wherein the plurality of slants slant from the first end and the second end of the shell toward the refrigerant outlet in the longitudinal direction.