Pre-Subcooler for a Condenser

This application claims priority from and the benefit of U.S. Provisional Application No. 63/351,711, entitled “PRE-SUBCOOLER FOR A CONDENSER,” filed Jun. 13, 2022, which is herein incorporated by reference in its entirety for all purposes.

This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

Chiller systems, or vapor compression systems, utilize a working fluid (e.g., a refrigerant) that changes phases between vapor, liquid, and combinations thereof, in response to exposure to different temperatures and pressures within components of the chiller system. A chiller system may place the working fluid in a heat exchange relationship with a conditioning fluid (e.g., water) and may deliver the conditioning fluid to conditioning equipment and/or to a conditioned environment serviced by the chiller system. In such applications, the conditioning fluid may be passed through downstream equipment, such as air handlers, to condition other fluids, such as air in a building.

Traditional chiller systems include a refrigerant circuit having, for example, a compressor, a condenser, and an evaporator. In some condensers, one or more tube bundles may be positioned in a shell or housing of the condenser. Refrigerant vapor may be directed into the shell, and a cooling fluid may be circulated through tubes of the tube bundle to enable heat transfer from the refrigerant to the cooling fluid. The transfer or exchange of heat between the refrigerant vapor and the cooling fluid may cause the refrigerant vapor to condense or change into a liquid phase. Before the refrigerant liquid is discharged from the condenser, the refrigerant liquid may be further cooled (e.g., subcooled) by cooling fluid circulated through an additional tube bundle, which may be referred to as a subcooler, positioned within the shell of the condenser to transfer additional heat from the condensed refrigerant liquid to the cooling fluid. Unfortunately, heat transfer efficiencies of existing condenser designs may be limited.

A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

In one embodiment, a condenser of a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a shell configured to receive vapor heat transfer fluid and a condensing section. A first plurality of heat exchange tubes is configured to place the vapor heat transfer fluid in a heat exchange relationship with cooling fluid to produce liquid heat transfer fluid. The condenser includes a subcooling section having a second plurality of heat exchange tubes extending within the shell, where the second plurality of heat exchange tubes is configured to place the liquid heat transfer fluid in a heat exchange relationship with cooling fluid to subcool the liquid heat transfer fluid. The condenser includes a pre-subcooler disposed in the condensing section, where the pre-subcooler includes a trough configured to collect a portion of the liquid heat transfer fluid and direct the portion of the liquid heat transfer fluid to the subcooling section.

In another embodiment, a method includes directing vapor heat transfer fluid across a first plurality of heat exchange tubes of a condensing section of a condenser to place the vapor heat transfer fluid in a heat exchange relationship with cooling fluid directed through the first plurality of heat exchange tubes. The first plurality of heat exchange tubes is configured to condense the vapor heat transfer fluid to produce liquid heat transfer fluid. The method includes directing the liquid heat transfer fluid across a second plurality of heat exchange tubes of a subcooling section of the condenser to place the liquid heat transfer fluid in a heat exchange relationship with cooling fluid directed through the second plurality of heat exchange tubes, where the second plurality of heat exchange tubes is configured to subcool the liquid heat transfer fluid. The method includes collecting, via a pre-subcooler disposed in the condensing section, a portion of the liquid heat transfer fluid condensed by a first tube bundle of the first plurality of heat exchange tubes. The method includes directing the portion of the liquid heat transfer fluid from the pre-subcooler toward longitudinal ends of a second tube bundle of the first plurality of heat exchange tubes.

In another embodiment, a condenser of a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system includes a shell configured to receive vapor heat transfer fluid. The condenser includes a condensing section having a first tube bundle and a second tube bundle extending within the shell, where the first tube bundle and the second tube bundle are configured to place the vapor heat transfer fluid in a heat exchange relationship with cooling fluid to produce liquid heat transfer fluid from the vapor heat transfer fluid. The condenser includes a pre-subcooler disposed between the first tube bundle and the second tube bundle, where the pre-subcooler includes a trough configured to collect a portion of the liquid heat transfer fluid produced by the first tube bundle. The condenser includes a subcooling section having a plurality of heat exchange tubes extending within the shell, where the pre-subcooler is configured to direct the portion of the liquid heat transfer fluid to the subcooling section. The plurality of heat exchange tubes is configured to place the portion of the liquid heat transfer fluid in a heat exchange relationship with cooling fluid directed through the plurality of heat exchange tubes to subcool the portion of the liquid heat transfer fluid.

One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the present disclosure, 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. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

As used herein, the terms “approximately,” “generally,” “substantially,” and so forth, are intended to convey that the property value being described may be within a relatively small range of the property value, as those of ordinary skill would understand. For example, when a property value is described as being “approximately” equal to (or, for example, “substantially similar” to) a given value, this is intended to convey that the property value may be within +/−5%, within +/−4%, within +/−%, within +/−2%, within +/−1%, or even closer, of the given value. Similarly, when a given feature is described as being “substantially parallel” to another feature, “generally perpendicular” to another feature, and so forth, this is intended to convey that the given feature is within +/−5%, within +/−4%, within +/−3%, within +/−2%, within +/−1%, or even closer, to having the described nature, such as being parallel to another feature, being perpendicular to another feature, and so forth. Mathematical terms, such as “parallel” and “perpendicular,” should not be rigidly interpreted in a strict mathematical sense, but should instead be interpreted as one of ordinary skill in the art would interpret such terms. For example, one of ordinary skill in the art would understand that two lines that are substantially parallel to each other are parallel to a substantial degree, but may have minor deviation from exactly parallel.

Embodiments of the present disclosure relate to a heating, ventilation, air conditioning, and refrigeration (HVAC&R) system, such as a chiller system. The HVAC&R system may include a vapor compression system (e.g., vapor compression circuit) through which a heat transfer fluid (e.g., a working fluid), such as a refrigerant, is directed in order to heat and/or cool a conditioning fluid. As an example, the vapor compression system may include a compressor configured to pressurize the heat transfer fluid and to direct the pressurized heat transfer fluid to a condenser configured to cool and condense the pressurized heat transfer fluid. An evaporator of the vapor compression system may receive the cooled, condensed heat transfer fluid and may place the cooled, condensed heat transfer fluid in a heat exchange relationship with the conditioning fluid to absorb thermal energy or heat from the conditioning fluid, thereby cooling the conditioning fluid. The cooled conditioning fluid may then be directed to conditioning equipment, such as air handlers and/or terminal units, for use in conditioning air supplied to a building or other conditioned space.

In general, the condenser is configured to cool the pressurized heat transfer fluid by placing the pressurized heat transfer fluid in a heat exchange relationship with a cooling fluid, such as air, water, brine, or other fluid. For example, the condenser may have a shell or housing defining an inner volume configured to receive the pressurized heat transfer fluid from the compressor, and the condenser may include a plurality of tubes (e.g., one or more tube bundles, condensing tubes) disposed within the inner volume of the shell. The plurality of tubes is configured to circulate the cooling fluid (e.g., water or brine) through the plurality of tubes to enable heat transfer from the pressurized heat transfer fluid to the cooling fluid.

In some embodiments, the condenser may include a subcooler configured to further cool (e.g., subcool) the heat transfer fluid once it has condensed within the condenser (e.g., via heat exchange with the cooling fluid directed through the plurality of tubes). For example, the condenser may include an additional plurality of tubes (e.g., an additional tube bundle, subcooling tubes) disposed within the shell and configured to circulate cooling fluid to further cool the heat transfer fluid. Unfortunately, existing condenser designs may be susceptible to inefficiencies. For example, as vapor heat transfer fluid flows across the condensing tubes within the condenser, the vapor heat transfer fluid may condense into liquid heat transfer fluid, and a film of the liquid heat transfer fluid may form on one or more of the condensing tubes. As liquid film (e.g., heat transfer fluid liquid film, refrigerant liquid film) forms on the tubes and/or resides on the tubes, a heat transfer efficiency of the condenser may be reduced. That is, a heat transfer rate between the cooling fluid within the tubes of the condenser and the heat transfer fluid within the condenser may be reduced.

Accordingly, present embodiments are directed to a system and method configured to reduce formation of liquid film on condensing tubes of a condenser, which may improve a heat transfer rate and/or heat transfer efficiency of the condenser. In particular, the present embodiments include a pre-subcooler positioned within a condensing section of the condenser. The pre-subcooler is configured to collect heat transfer fluid liquid that forms from heat transfer fluid vapor within the condensing section and is configured to direct the liquid heat transfer fluid to a subcooler of the condenser. In this way, the pre-subcooler may block flow of liquid heat transfer fluid to one or more condensing tubes in the condensing section (e.g., downstream of the pre-subcooler, relative to a direction of heat transfer fluid flow; beneath the pre-subcooler, relative to a direction of gravity), thereby blocking formation or collection of a liquid heat transfer fluid film on the condensing section. As a result, the condensing tubes downstream of the pre-subcooler may benefit from improved heat transfer with vapor heat transfer fluid directed thereacross.

The pre-subcooler may include a trough extending longitudinally along the condenser and within the condensing section. The trough may include a sheet or panel and flanges extending from lateral sides (e.g., edges) of the sheet. The trough may define a basin configured to collect liquid heat transfer fluid that is formed as vapor heat transfer fluid condenses within the condensing section. Further, one or more tubes within the condensing section, which may be referred to as pre-subcooler tubes, may extend within the basin of the trough. Thus, liquid heat transfer fluid collected within the basin may be further cooled or subcooled via cooling fluid directed through the pre-subcooler tubes. The liquid heat transfer fluid collected within the basin of the trough may flow toward longitudinal ends of the trough (e.g., via gravity) and may flow out of the trough towards the subcooler of the condenser. The flanges of the trough (e.g., a first flange and a second flange of the trough) may retain the condensed heat transfer fluid and direct the condensed heat transfer fluid toward longitudinal ends of the pre-subcooler. As described in detail below, tubes of the condensing section disposed beneath the pre-subcooler (e.g., relative to gravity) may receive a reduced amount of condensed (e.g., liquid) heat transfer fluid from the condensing tubes disposed above the pre-subcooler. Accordingly, contact between remaining heat transfer fluid vapor within the condenser and the condensing tubes disposed beneath the pre-subcooler may be improved (e.g., due to reduced liquid film formed or residing on the condensing tubes), thereby improving heat transfer efficiency of the condenser. In this way, the pre-subcooler of the present disclosure improves efficiency of the condenser and the HVAC&R system.

Turning now to the drawings,is a perspective view of an embodiment of an environment for a heating, ventilation, air conditioning, and refrigeration (HVAC&R) systemin a buildingfor a typical commercial setting. The HVAC&R systemmay include a vapor compression systemthat supplies a chilled liquid, which may be used to cool the building. The HVAC&R systemmay also include a boilerto supply warm liquid to heat the buildingand an air distribution system which circulates air through the building. The air distribution system can also include an air return duct, an air supply duct, and/or an air handler. In some embodiments, the air handlermay include a heat exchanger that is connected to the boilerand the vapor compression systemby conduits. The heat exchanger in the air handlermay receive either heated liquid from the boileror chilled liquid from the vapor compression system, depending on the mode of operation of the HVAC&R system. The HVAC&R systemis shown with a separate air handler on each floor of building, but in other embodiments, the HVAC&R systemmay include air handlersand/or other components that may be shared between or among floors.

illustrate embodiments of the vapor compression systemthat can be used in the HVAC&R system. The vapor compression systemmay circulate a heat transfer fluid (e.g., a refrigerant) through a circuit starting with a compressor. The circuit may also include a condenser, an expansion valve(s) or device(s), and a liquid chiller or an evaporator. The vapor compression systemmay further include a control panel(e.g., controller) that has an analog to digital (A/D) converter, a microprocessor, a non-volatile memory, and/or an interface board.

In some embodiments, the vapor compression systemmay use one or more of a variable speed drive (VSDs), a motor, the compressor, the condenser, the expansion valve or device, and/or the evaporator. The motormay drive the compressorand may be powered by a variable speed drive (VSD). The VSDreceives alternating current (AC) power having a particular fixed line voltage and fixed line frequency from an AC power source, and provides power having a variable voltage and frequency to the motor. In other embodiments, the motormay be powered directly from an AC or direct current (DC) power source. The motormay include any type of electric motor that can be powered by a VSD or directly from an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor.

The compressorcompresses a heat transfer fluid vapor and delivers the vapor to the condenserthrough a discharge passage. In some embodiments, the compressormay be a centrifugal compressor. The heat transfer fluid vapor delivered by the compressorto the condensermay transfer heat to a cooling fluid (e.g., water or air) in the condenser. The heat transfer fluid vapor may condense to a heat transfer fluid liquid in the condenseras a result of thermal heat transfer with the cooling fluid. The heat transfer fluid liquid from the condensermay flow through the expansion deviceto the evaporator. In the illustrated embodiment of, the condenseris water cooled and includes a tube bundleconnected to a cooling tower, which supplies the cooling fluid to the condenser.

The heat transfer fluid liquid delivered to the evaporatormay absorb heat from another cooling fluid, which may or may not be the same cooling fluid used in the condenser. The heat transfer fluid liquid in the evaporatormay undergo a phase change from the heat transfer fluid liquid to a heat transfer fluid vapor. As shown in the illustrated embodiment of, the evaporatormay include a tube bundlehaving a supply lineS and a return lineR connected to a cooling load. The cooling fluid of the evaporator(e.g., water, ethylene glycol, calcium chloride brine, sodium chloride brine, or any other suitable fluid) enters the evaporatorvia return lineR and exits the evaporatorvia supply lineS. The evaporatormay reduce the temperature of the cooling fluid in the tube bundlevia thermal heat transfer with the heat transfer fluid. The tube bundlein the evaporatorcan include a plurality of tubes and/or a plurality of tube bundles. In any case, the heat transfer fluid vapor exits the evaporatorand returns to the compressorby a suction line to complete the cycle.

is a schematic of the vapor compression systemwith an intermediate circuitincorporated between condenserand the expansion device. The intermediate circuitmay have an inlet linethat is directly fluidly connected to the condenser. In other embodiments, the inlet linemay be indirectly fluidly coupled to the condenser. As shown in the illustrated embodiment of, the inlet lineincludes a first expansion devicepositioned upstream of an intermediate vessel. In some embodiments, the intermediate vesselmay be a flash tank (e.g., a flash intercooler). In other embodiments, the intermediate vesselmay be configured as a heat exchanger or a “surface economizer.” In the illustrated embodiment of, the intermediate vesselis used as a flash tank, and the first expansion deviceis configured to lower the pressure of (e.g., expand) the liquid heat transfer fluid received from the condenser. During the expansion process, a portion of the liquid may vaporize, and thus, the intermediate vesselmay be used to separate the vapor from the liquid received from the first expansion device.

Additionally, the intermediate vesselmay provide for further expansion of the liquid heat transfer fluid because of a pressure drop experienced by the liquid heat transfer fluid when entering the intermediate vessel(e.g., due to a rapid increase in volume experienced when entering the intermediate vessel). The vapor in the intermediate vesselmay be drawn by the compressorthrough a suction lineof the compressor. In other embodiments, the vapor in the intermediate vessel may be drawn to an intermediate stage of the compressor(e.g., not the suction stage). The liquid that collects in the intermediate vesselmay be at a lower enthalpy than the liquid heat transfer fluid exiting the condenserdue to expansion in the expansion deviceand/or the intermediate vessel. The liquid from intermediate vesselmay then flow in linethrough a second expansion deviceto the evaporator.

It should be appreciated that any of the features described herein may be incorporated with the vapor compression systemor any other suitable HVAC&R system. As mentioned above, embodiments of the present disclosure are directed to a pre-subcooler that may be utilized with the condenserof the vapor compression system. The pre-subcooler may be disposed within a condensing section of the condenserthat is configured to condense vapor heat transfer fluid received by the condenser. As described in further detail below, the pre-subcooler may be configured to collect liquid heat transfer fluid that forms within the condensing section and direct the liquid heat transfer fluid toward a subcooler of the condenser. In some embodiments, the pre-subcooler may also subcool the collected liquid heat transfer fluid. The pre-subcooler enables improved heat transfer between tubes in the condensing section and vapor heat transfer fluid by enabling reduced formation of liquid film (e.g., liquid heat transfer fluid film) on the tubes.

is a schematic cross-sectional side view of an embodiment of a condenserin accordance with aspects of the present disclosure. The condensermay be an embodiment of the condenserof the vapor compression systemdescribed above. The condenserincludes a shellthat defines an inner volumeand separates the inner volumefrom an exterior environment. In some embodiments, the shellmay be formed from a metal and may have a generally cylindrical shape. As indicated by arrow, the condenser(e.g., the shell) is configured to receive a heat transfer fluid (e.g., vapor heat transfer fluid, refrigerant vapor) circulated through the vapor compression system. The condensermay place the heat transfer fluid in a heat exchange relationship with a cooling fluid (e.g., water, brine). For example, the condensermay include a plurality of heat exchange tubesconfigured to direct the cooling fluid therethrough, and the heat transfer fluid within the condensermay flow across the heat exchange tubesand transfer heat to the cooling fluid. As discussed further below, the heat exchange tubesmay be grouped in one or more tube bundles and/or one or more sections. For example, the condensermay define a condensing section having corresponding heat exchange tubesconfigured to condense vapor heat transfer fluid received by the condenserto form liquid heat transfer fluid. The condensermay also define a subcooling section (e.g., a subcooler) having corresponding heat exchange tubesconfigured to further cool or subcool the liquid heat transfer fluid formed in the condenser.

As mentioned above, the heat exchange tubesare configured to direct a cooling fluid through the condenser. In the illustrated embodiment, the condenseris a multi-pass heat exchanger and is configured to direct the cooling fluid therethrough along multiple passes (e.g., arranged in series with one another). In particular, the condenserdefines a first pass, which may include a first subset of the heat exchange tubes, and a second pass, which may include a second subset of the heat exchange tubes. Thus, at least a portion of the heat transfer fluid may be directed across the heat exchanges tubesof the second passand then be directed across the heat exchange tubesof the first passbefore the heat transfer fluid is discharged from the condenseras indicated by arrow.

In operation, the condensermay receive a flow of the cooling fluid, as indicated by arrow. The cooling fluid may enter the condenservia a first cooling fluid section(e.g., cooling fluid box, water box). The first cooling fluid sectionis divided into an inlet sectionand an outlet sectionthat are separated (e.g., fluidly separated) by a divider plate. The cooling fluid may be directed into the inlet sectionand may then be directed into the heat exchange tubesof the first pass, as indicated by arrow. The heat exchange tubesof the first passmay include condensing tubes and subcooling tubes, as described further below. The cooling fluid may travel through the heat exchange tubesof the first pass(e.g., along a lengthof the condenser) and may be discharged into a second cooling fluid sectiondisposed at an end of the condenseropposite the first cooling fluid section. The second cooling fluid sectionmay direct the cooling fluid (e.g., a first flow of cooling fluid) into the heat exchange tubesassociated with the second pass, as indicated by arrow. At least a portion of the heat exchange tubesassociated with the second passmay be condensing tubes. The cooling fluid may flow into the heat exchange tubesof the second passand into the outlet sectionof the first cooling fluid section, as indicated by arrow, and may then be discharged from the first cooling fluid sectionand the condenser, as indicated by arrow. As such, the cooling fluid may flow sequentially through the first passand the second pass.

As mentioned above, vapor heat transfer fluid (e.g., gaseous heat transfer fluid) may be directed into the shellof the condenser. The vapor heat transfer fluid first flows across heat exchange tubesof the second pass. As the vapor heat transfer fluid contacts heat exchange tubesof the second pass, heat is transferred from the cooling fluid within the heat exchange tubesto the vapor heat transfer fluid, which causes the vapor heat transfer fluid to condense and form liquid heat transfer fluid. In some instances, as the heat transfer fluid continues to flow across the heat exchange tubesof the second pass, and thereafter flow across the heat exchange tubesof the first pass, condensed liquid heat transfer fluid may form a liquid film on one or more of the heat exchange tubes(e.g., of the second pass, the first pass, or both). Unfortunately, formation and/or accumulation of liquid film (e.g., liquid heat transfer fluid film) on the heat exchange tubesmay reduce heat transfer efficiency between the heat exchange tubesand the heat transfer fluid.

Accordingly, present embodiments of the condenserinclude a pre-subcoolerconfigured to enable a reduction in liquid film (e.g., condensed, liquid heat transfer fluid) formed on heat exchange tubeswithin the condenser. In the illustrated embodiment, the pre-subcooleris positioned at least partially within the second passand/or at least partially within a region(e.g., gap, space) extending between (e.g., vertically between) the first passand the second pass(e.g., a region without heat exchange tubes). The pre-subcoolerincludes a troughconfigured to collect condensed, liquid heat transfer fluid formed via heat exchange with the heat exchange tubesof the second pass. As described further below, the troughmay include a sheet or panel (e.g., horizontal sheet) extending along the lengthof the condenser(e.g., along the second pass) and lateral sides or segments (e.g., vertical segments) extending from edges of the panel and along the length of the condenser. In some embodiments, the troughmay be formed from a solid (e.g., non-perforated) piece of material. The troughmay extend substantially horizontally (e.g., with respect to gravity) along the lengthof the condenserand/or along a width (e.g., a dimension extending cross-wise to the length) of the condenser. That is, a plane formed by a panel (e.g., a lower panel, with respect to a direction of gravity) of the troughmay include a slope (e.g., with respect to gravity) that is substantially negligible (e.g., less than 5 degrees, less than 1 degree) along the lengthof the condenserand/or along the width of the condenser.

Liquid heat transfer fluid collected within the troughmay flow (e.g., via force of gravity) towards longitudinal endsof the pre-subcooler, as indicated by arrows. That is, as liquid heat transfer fluid accumulates within the relatively horizontal basin formed by the trough, gravity may naturally force the heat transfer fluid toward the longitudinal endsof the trough. The longitudinal endsmay enable the heat transfer fluid to flow therethrough (e.g., via one or more openings formed in the longitudinal ends). As such, at the longitudinal ends, the liquid heat transfer fluid may flow out of the trough(e.g., in a vertically downward direction) toward the first pass(e.g., toward a subcooler of the condenser). In this way, the liquid heat transfer fluid collected within the troughmay not flow across one or more heat exchange tubesof the first passand/or may not flow across a substantial portion of the heat exchange tubesof the first pass. Thus, liquid film may not form on heat exchange tubesof the first pass, which may improve heat transfer efficiency of the heat exchange tubesof the first passand the condensergenerally.

In some embodiments, the longitudinal endsmay be configured to retain a threshold level of heat transfer fluid within the troughduring operation of the condenser. For example, the longitudinal endsmay be configured to block flow of heat transfer fluid from a basin of the troughtoward the first passuntil a threshold quantity (e.g., a threshold level) of heat transfer fluid has accumulated within the trough. The longitudinal endsmay be configured (e.g., via openings formed therein, by having a designed height) to allow heat transfer fluid (e.g., liquid heat transfer fluid) to flow out of the trough(e.g., from the troughto the first pass) once the level of heat transfer fluid within the troughexceeds the threshold quantity. As such, the longitudinal endsmay ensure that tubes (e.g., pre-subcooler tubes) within the troughremain submerged (e.g., partially submerged, fully submerged) in heat transfer fluid within the troughduring operation of the condenserto facilitate heat exchange with and subcooling of the heat transfer fluid within the trough.

It should be understood that, in certain embodiments, the troughmay include a slope configured to direct heat transfer fluid that may be accumulated within the troughtoward one of the longitudinal ends. In other embodiments, a first portion of the troughmay include a first slope configured to direct heat transfer fluid accumulated within the first portion of the troughtoward one of the longitudinal ends, while a second portion (e.g., a remaining portion) of the troughmay include a second slope configured to direct heat transfer fluid accumulated within the second portion of the troughtoward an opposing one of the longitudinal ends.

As described further below, one or more heat exchange tubesof the second passmay extend within the trough(e.g., within a basin of the trough). Thus, liquid heat transfer fluid collected within the troughmay be placed in a heat exchange relationship with the heat exchange tubesextending within the trough. To enable subcooling of the liquid heat transfer fluid within the trough, the heat exchange tubesextending within the troughmay not receive the cooling fluid directed through remaining heat exchange tubesof the second pass. Instead, cooling fluid from the inlet sectionof the first cooling fluid sectionmay be directed to the heat exchange tubesextending within the trough(e.g., without first being directed through the first passor the second pass).

For example, the condensermay include a conduit(e.g., pipe, manifold, nozzle, etc.) extending between and fluidly coupling the inlet sectionof the first cooling fluid sectionand the heat exchange tubesextending within the trough, which may be longer than the heat exchange tubesof second pass(e.g., condensing heat exchange tubes). For example, the conduitmay extend through the divider plate. The divider plateand the conduitmay be coupled to one another in a sealing engagement to block flow of cooling fluid directly from the inlet sectionto the outlet sectionof the first cooling fluid section. As will be appreciated, the cooling fluid within the inlet sectionof the first cooling fluid sectionmay be colder than the cooling fluid directed from the second cooling fluid sectioninto heat exchange tubesof the second pass. Thus, the cooling fluid directed from the inlet sectionof the first cooling fluid sectionand through the heat exchange tubesextending within the troughmay enable further cooling and/or subcooling of the liquid heat transfer fluid collected within the trough. Cooling fluid directed through the heat exchange tubesextending within the troughmay be discharged into the second cooling fluid section, and the second cooling fluid sectionmay then direct the cooling fluid (e.g., a second flow of cooling fluid) into the heat exchange tubesof the second pass, as indicated by arrow. As such, the flow of cooling fluid (e.g., indicated by arrow) discharged from the heat exchange tubesextending within the troughmay mix (e.g., in the second cooling fluid section) with cooling fluid (e.g., indicated by arrow) received from the first pass. Arrangements of the heat exchange tubeswithin the condenserand embodiments of the pre-subcoolerare described in further detail below.

is a cross-sectional axial view of an embodiment of the condenserincluding the pre-subcooler. In the illustrated embodiment, the heat exchange tubesare arranged in a first tube bundle, a second tube bundle, and a third tube bundle. The first tube bundlegenerally defines the second passconfigured to direct cooling fluid through the condenser. However, as described below, one or more of the heat exchange tubesof the first tube bundlemay not be associated with the second pass. The second tube bundleand third tube bundledefine the first passconfigured to direct cooling fluid through the condenser.

In the illustrated embodiment, the first tube bundleand the second tube bundlemay generally define a condensing sectionof the condenser. That is, heat transfer fluid directed across the heat exchange tubesof the first tube bundleand the second tube bundle(e.g., along a vertical axis) may be vapor heat transfer fluid that condenses to form liquid heat transfer fluid. Thus, heat transfer fluid that flows to the third tube bundlemay be substantially in a liquid phase. Accordingly, the third tube bundlemay generally define a subcooling section(e.g., subcooler) of the condenser. Liquid heat transfer fluid flowing along and/or across the heat exchange tubesof the third tube bundlemay be further cooled and/or subcooled before the heat transfer fluid is discharged from the condenser. The subcooling sectionmay have any suitable configuration. For example, in some embodiments, the subcooling sectionmay define multiple passes (e.g., heat transfer fluid passes) whereby heat transfer fluid may flow sequentially across and/or along different groups of heat exchanger tubesin the subcooling section.

The condenseralso includes the pre-subcoolerhaving the trough. The troughis disposed within the condensing sectionand is at least partially disposed within the regionextending between (e.g., extending vertically between, relative to vertical axis) the first tube bundleand the second tube bundle. In some embodiments, the troughmay be completely disposed within the region. In particular, a sheet(e.g., horizontal sheet relative to gravity) of the troughextends within the region(e.g., along a lateral axisor horizontal axis). The troughalso includes lateral segments(e.g., vertical segments, flanges) extending from lateral edges or sides of the sheet. That is, the lateral segmentsmay extend cross-wise from lateral edges or sides of the sheet. In some embodiments, a single piece of material (e.g., sheet metal) may be utilized (e.g., bent) to form the troughhaving the sheetand the lateral segments. In other embodiments, the sheetand the lateral segmentsmay be separate components mechanically fastened to one another (e.g., via welding, bolts, rivets, etc.). The sheet, the lateral segments, or both, may be solid (e.g., non-porous, non-perforated) pieces of material. That is, the sheet, the lateral segments, or both, may not include perforations (e.g., apertures) formed therein, such that fluid flow through a thickness of the sheet, through thicknesses of the lateral segments, or both, may be blocked.

The sheetand the lateral segmentscooperatively define a basin(e.g., reservoir, volume) of the trough. As vapor heat transfer fluid is directed across the heat exchange tubesof the first tube bundle, some of the vapor heat transfer fluid may condense to form liquid heat transfer fluid, and the liquid heat transfer fluid may be captured within the basinof the trough. That is, liquid heat transfer fluid that may be formed on at least a portionof the first tube bundlemay flow (e.g., drip) from the portionof the first tube bundleinto the basin. The portionmay include some of or all of the tubes included in the first tube bundle.

The liquid heat transfer fluid within the basinmay be directed (e.g., via force of gravity) to the longitudinal endsof the trough. From the longitudinal ends, the liquid heat transfer fluid may flow downward (e.g., along vertical axis) across longitudinal ends of the heat exchange tubesof the second tube bundle. In some embodiments, the longitudinal ends of the heat exchange tubesof the second tube bundlemay include designated portions of a length of the heat exchange tubesof the second tube bundle. For example, the designated portions may be a percentage of a length of the heat exchange tubesof the second tube bundle(e.g., 5 percent, 10 percent) extending from corresponding distal ends of the heat exchange tubesof the second tube bundle. Additionally or alternatively, the liquid heat transfer fluid may be directed to the subcooling section(e.g., after contacting the longitudinal ends of the tubes of the second tube bundle, without contacting tubes of the second tube bundle) where the liquid heat transfer fluid may be further cooled and/or subcooled prior to discharge of the liquid heat transfer fluid from the condenser. In this way, the liquid heat transfer fluid collected within the troughdoes not contact a substantial portion of the heat exchange tubesof the second tube bundle, which reduces formation of liquid film on a substantial portion of the heat exchange tubesof the second tube bundleand therefore improves heat transfer of remaining vapor heat transfer fluid via the second tube bundle. That is, vapor heat transfer fluid that does not condense and collect within the troughas liquid heat transfer fluid may continue flowing across the first tube bundleand subsequently flow across the second tube bundleand undergo more efficient heat transfer via the heat exchange tubesof the first tube bundleand second tube bundledisposed beneath (e.g., relative to the vertical axis) the trough.

As mentioned above, one or more heat exchange tubesmay be disposed within the basindefined by the trough. For example, heat exchange tubesdisposed within the basinmay be referred to as pre-subcooler tubes. In some embodiments, the lateral segmentsmay protrude vertically beyond (e.g., along the axis) the pre-subcooler tubes, such that the pre-subcooler tubesmay be disposed completely within the basinwith respect to the vertical axis. In other embodiments, a portion of the pre-subcooler tubesmay protrude beyond (e.g., above, with respect to a direction of gravity) the basin.

While the pre-subcooler tubesmay be arranged with and/or adjacent the heat exchange tubesof the first tube bundle, the pre-subcooler tubesmay not receive the same flow of cooling fluid that is received by the heat exchange tubesof the first tube bundle, in some embodiments. For example, as described above, cooling fluid from the inlet sectionof the first cooling fluid sectionmay be directed into (e.g., directly into) the pre-subcooler tubesvia the conduit. Thus, the pre-subcooler tubesmay define a pre-subcooler pass of the condenser, and cooling fluid directed through the pre-subcooler tubesmay bypass the heat exchange tubesof the first pass. However, in other embodiments, the pre-subcooler tubesmay receive the cooling fluid from the second cooling fluid section, similar to the heat exchange tubesof the first tube bundle.

As liquid heat transfer fluid flows within the basintoward the longitudinal endsof the pre-subcooler, the liquid heat transfer fluid may be further cooled (e.g., pre-subcooled) and/or subcooled via heat exchange with the pre-subcooler tubes. Indeed, in some embodiments, the pre-subcooler tubesmay be at least partially immersed in liquid heat transfer fluid collected within the trough. Thus, the pre-subcooler tubesmay effectively further cool the liquid heat transfer fluid prior to discharge of the liquid heat transfer fluid from the trough.

As shown in the illustrated embodiment, the pre-subcoolerincludes a width, which may be a dimension extending between the lateral segmentsof the trough. In other words, the widthmay be a dimension of the sheetextending along the lateral axis. A magnitude of the widthmay be different for different embodiments of the pre-subcooler. As will be appreciated, the widthof the pre-subcooler(e.g., the trough) may affect with a pressure drop of vapor heat transfer fluid flowing through the condenser. Accordingly, a magnitude of the widthmay be selected to achieve a desired pressure drop of vapor heat transfer fluid. In some embodiments, the magnitude of the widthmay be determined or selected based on a position of the pre-subcoolerwithin the shell(e.g., a vertical position, along the vertical axis, of the troughwithin the condenser). Indeed, an amount of remaining vapor heat transfer fluid (e.g., vapor heat transfer fluid that does condense to liquid heat transfer fluid collected within the trough) that flows across heat exchange tubesdisposed beneath the troughmay be dependent on a vertical position of the pre-subcoolerwithin the shell. In some embodiments, a higher position of the pre-subcoolerwithin the shell(e.g., along vertical axis, relative to gravity) may correspond to a reduced magnitude of the width.

As mentioned above, the trough(e.g., the sheet) may be positioned within the regionbetween the first tube bundleand the second tube bundle(e.g., vertically between the first passand the second pass) where heat exchange tubesare not located. Thus, in some embodiments, the pre-subcoolermay be incorporated with the condenserand without modifying a number of the heat exchange tubes(e.g., relative to an embodiment of the condenserwithout the pre-subcooler), which may further contribute to improved heat transfer efficiency of the condenserwith the pre-subcooler. However, it should be appreciated that the pre-subcoolermay be disposed in any suitable location within the condenserbased on operating condition considerations, including but not limited to heat transfer fluid pressure drop, number of total heat exchange tubes, number of pre-subcooler tubes, number of passes (e.g., cooling fluid passes), and so forth.

is a cross-sectional axial view of an embodiment of the condenserincluding the pre-subcooler. In the illustrated embodiment, the pre-subcoolerincludes two separate troughs. Thus, the condensermay be described as including two pre-subcoolers(e.g., a first pre-subcoolerand a second pre-subcooler). Each troughincludes the sheetand the lateral segmentsdiscussed above. As in the embodiment described above with reference to, the troughsmay be disposed within the regionbetween the first tube bundleand the second tube bundle. The respective sheetsof the first pre-subcoolerand the second pre-subcoolermay be aligned with one another along the lateral axisor may be vertically offset from one another along the vertical axis. Each troughis configured to receive and collect liquid heat transfer fluid that is condensed via heat exchange tubesof the second pass(e.g., the first tube bundle). However, in other embodiments, the troughsmay be vertically offset from one another and may receive liquid heat transfer fluid condensed via different heat exchange tubesand/or different tube bundles within the condenser.

The respective pre-subcooler tubesdisposed within the respective troughsmay each receive cooling fluid from the inlet sectionof the first cooling fluid section, or the respective pre-subcooler tubesmay receive cooling fluid from different portions of the condenser. Further, the pre-subcoolerseach include the width, which may be the same or different from one another and may be selected based on the factors discussed above. In some embodiments, the condenserhaving the first pre-subcoolerand the second pre-subcoolermay enable a reduced pressure drop of vapor heat transfer fluid within the condenser(e.g., as compared to an embodiment of the condenserhaving one pre-subcooler). The first pre-subcoolerand the second pre-subcoolerare also configured to operate in a similar manner as that described above. In other embodiments, the pre-subcoolermay include 1, 2, 3, 4, 5, or more than 5 separate troughsdisposed along various locations and/or at various orientations within the condenser.

is a schematic cross-sectional side view of an embodiment of the condenserincluding the pre-subcoolerand flow of liquid heat transfer fluid through the condenser. As described above, the pre-subcoolerincludes the trough, which may be positioned at least partially between the first tube bundleand the second tube bundlethat cooperatively define the condensing sectionof the condenser. The condenser also includes the subcooling sectionhaving the third tube bundle.

In the illustrated embodiment, the subcooling section(e.g., subcooler) is a two pass subcooler. That is, the subcooling sectiondefines two passes (e.g., a first passand a second pass) that cooperatively define a heat transfer fluid flow path through the subcooling section. The heat exchange tubesof the third tube bundlemay be divided into a first group of heat exchange tubesassociated with the first pass(e.g., a first subcooler pass) and a second group of heat exchange tubesassociated with the second pass(e.g., a second subcooler pass). The subcooling sectionalso includes a separation plateextending between (e.g., relative to vertical axis) the heat exchange tubesof the first passand the heat exchange tubesof the second pass. The separation plategenerally extends along a longitudinal axisof the condenser. In some embodiments, the separation platemay be a solid piece of material (e.g., a non-perforated piece of material) that does not include apertures formed therein.

The first passof the subcooling sectionmay be described as an open pass (e.g., an open subcooler section) that is, for example, configured to receive heat transfer fluid directly from the second tube bundle(e.g., the condensing section). That is, heat transfer fluid (e.g., liquid heat transfer fluid) may flow from the second tube bundledirectly to heat exchange tubesof the third tube bundleassociated with the first passof the subcooling section, as indicated by arrows. The heat transfer fluid may then be directed by the separation plate(e.g., via gravity) to flow along the heat exchange tubesof the first passtowards longitudinal endsof the separation plate, as indicated by arrows. At the longitudinal ends, the heat transfer fluid may flow from the first passto the second passof the subcooling sectionand be directed along the heat exchange tubesof the second pass, as indicated by arrows, to flow toward an outletof the condenser. The second passmay be described as a closed pass of the subcooling section. As the heat transfer fluid (e.g., liquid heat transfer fluid) flows along the first passand the second pass, the heat transfer fluid may be further cooled and/or subcooled via heat transfer with the cooling fluid directed through the heat exchange tubesof the subcooling section.

As discussed above, the troughof the pre-subcooleris configured to collect liquid condensate that forms via heat exchange with the first tube bundle. The liquid condensate may be captured within the basinof the troughdefined by the sheetand lateral segments. The troughis configured to direct the liquid condensate to the longitudinal endsof the trough. At the longitudinal ends, the liquid condensate may flow out of the troughand downward (e.g., along vertical axis), as indicated by arrows. As mentioned above, the liquid heat transfer fluid discharged from the troughmay flow across longitudinal endsof the heat exchange tubesin the second tube bundle. Thus, formation and/or accumulation of liquid heat transfer fluid film on a substantial portion (e.g., central portion) of the heat exchange tubesin the second tube bundleis avoided, which improves heat transfer between the second tube bundleand vapor heat transfer fluid that flows from the first tube bundleto the second tube bundle. That is, the troughmay be configured to direct liquid heat transfer fluid onto the longitudinal endsof the second tube bundleand to block flow of liquid heat transfer fluid from the trough(e.g., from the first tube bundle) onto the central portionof the second tube bundle. In some embodiments, the central portionmay correspond to a majority of a length of the second tube bundle(e.g., 50 percent of the length of the second tube bundle, 60 percent of the length of the second tube bundle, 70 percent of the length of the second tube bundle) and the longitudinal endsmay correspond to remaining portions of the length of the second tube bundle.