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 
       [0001]    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 
       [0002]    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 
       [0003]    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. 
         [0004]    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. 
         [0005]    Improvements may be made to such shell and tube heat exchangers, for example condensers. 
         [0006]    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. 
         [0007]    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. 
         [0008]    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. 
         [0009]    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. 
         [0010]    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. 
         [0011]    In some embodiments, the heat exchanger is a condenser. 
         [0012]    In some embodiments, the heat exchanger can be used in a chiller unit. 
         [0013]    In some embodiments, the chiller unit is used in an HVAC system. 
         [0014]    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 
         [0015]    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: 
           [0016]      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. 
           [0017]      FIG. 2  is a sectional or end view of the heat exchanger of  FIG. 1 . 
           [0018]      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. 
           [0019]      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. 
           [0020]      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. 
           [0021]      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. 
           [0022]      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. 
           [0023]      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. 
           [0024]      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. 
           [0025]      FIG. 10  is a partial sectional view showing the combination refrigerant displacement and drain device of  FIG. 9 . 
           [0026]      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. 
           [0027]      FIG. 12  is a partial sectional view showing the combination refrigerant displacement and drain device of  FIG. 9 . 
           [0028]      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. 
           [0029]      FIG. 14  is a partial end view showing the combination refrigerant displacement and drain device of  FIG. 13 . 
       
    
    
       [0030]    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 
       [0031]    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. 
         [0032]    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. 
         [0033]      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 . 
         [0034]      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. 
         [0035]      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. 
         [0036]      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 . 
         [0037]      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 . 
         [0038]      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. 
         [0039]      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. 
         [0040]      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 . 
         [0041]      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. 
         [0042]      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 . 
         [0043]      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 . 
         [0044]      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 . 
         [0045]    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.