Patent Publication Number: US-10782077-B2

Title: Refrigerant outlet device of a condenser

Description:
FIELD 
     The disclosure herein relates to heating, ventilation, and air-conditioning (“HVAC”) systems, such as for example a chiller, and more particularly to a condenser of a chiller system. Generally, methods, systems, and apparatuses are described that are directed to a refrigerant outlet device of a condenser in a chiller. 
     BACKGROUND 
     A HVAC system, such as a chiller, generally includes a compressor, a condenser, an evaporator and an expansion device. In a cooling cycle of the HVAC system, the compressor can compress refrigerant vapor, and the compressed refrigerant vapor may be directed into the condenser to be condensed into liquid refrigerant. The liquid refrigerant can then be expanded by the expansion device and directed into the evaporator. 
     Components of the HVAC system, such as the compressor, may include moving parts, and therefore may require lubrication during operation. Lubricants, such as oil, are commonly used in the HVAC system to provide lubrication. 
     SUMMARY 
     Embodiments provided herein relate to methods, systems and apparatuses configured to help provide lubrication in a HVAC system. In some HVAC systems, liquid refrigerant can be used to provide lubrication to, for example, moving parts, such as a bearing of a compressor. During an off-cycle, the compressor is turned off. Liquid refrigerant on the moving parts can vaporize, causing potential lack of liquid refrigerant for lubrication during the subsequent start-up. This may cause abnormal wear to the moving parts due to lack of lubrication, shortening the service lives of the moving parts. Improvements can be made to the HVAC system so that liquid refrigerant can be provided relatively fast, for example, to the moving parts, during for example a start-up. 
     A condenser equipped with a refrigerant outlet configured to receive and store liquid refrigerant, such as for example during an off-cycle. is described. In some embodiments, the refrigerant outlet may include an outflow pipe and an outer wall surrounding the outflow pipe. An outside surface of the outflow pipe and the outer wall can define an annular weir surrounding the outflow pipe. The annular weir can act as a reservoir to receive and store liquid refrigerant during, for example, an off-cycle. In some embodiments, after a start-up, the liquid refrigerant can be directed to the annular weir before flowing out of the outflow pipe so that the liquid refrigerant can be available in the annular weir. 
     In some embodiments, the outer wall may include a port in fluid communication with the weir. The port can be configured to direct the liquid refrigerant out of the weir to, for example, moving parts for lubrication. The moving parts may include, for example, a bearing of a compressor. 
     In some embodiments, the weir may be positioned below a bottom of the condenser in the vertical direction. The liquid refrigerant may be preferentially directed toward the weir before flowing out of the first end of the outflow pipe. 
     In some embodiments, the outflow pipe may have a first end and a second end, the first end is configured to be positioned inside the condenser, and the first end may be configured to be positioned in a vertical direction that is higher than an opening of the weir in a vertical direction. 
     In some embodiments, the port of the outer wall has a diameter, the outer wall and the outside surface of the outflow pipe have a distance therebetween, and the distance may be about the same as the diameter of the port. 
     The weir has a bottom in the vertical direction and the port has in the vertical direction a lowest point toward the bottom of the weir. In some embodiments, the lowest point of the port may be positioned in the vertical direction higher than the bottom of the weir. 
     In some embodiments, a method of providing liquid refrigerant during a start-up of a HVAC system may include: directing liquid refrigerant out of a condenser during an off-cycle; storing the liquid refrigerant in the reservoir; and directing the liquid refrigerant stored in the reservoir out of the reservoir during a HVAC system start-up. In some embodiments, a method of providing liquid refrigerant after a start-up of a HVAC system may include: preferentially directing liquid refrigerant toward a reservoir before the liquid refrigerant flowing out of an outflow pipe, and directing the liquid refrigerant out of the reservoir. In some embodiments, the liquid refrigerant can be directed out of the condenser from a location of the condenser that accumulates liquid refrigerant. 
     Other features and aspects of the fluid management approaches will become apparent by consideration of the following detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference is now made to the drawings in which like reference numbers represent corresponding parts throughout. 
         FIGS. 1A to 1C  illustrate a condenser equipped with a refrigerant outlet, according to one embodiment.  FIG. 1A  illustrates a portion of the condenser that includes the refrigerant outlet.  FIG. 1B  illustrates an enlarged sectional view of the refrigerant outlet.  FIG. 1C  illustrates a top sectional view of the refrigerant outlet along the line  1 C- 1 C in  FIG. 1B . 
         FIG. 2  illustrates a sectional view of a condenser equipped with a refrigerant outlet, according to another embodiment. 
         FIG. 3  illustrates another embodiment of a refrigerant outlet. 
         FIG. 4  illustrates yet another embodiment of a refrigerant outlet. 
     
    
    
     DETAILED DESCRIPTION 
     A HVAC system, such as a chiller system, may commonly include components with moving parts, such as a bearing of a compressor. The moving parts generally require proper lubrication. The lubrication is commonly provided by lubricants, such as oil. In some HVAC systems, the lubrication can be provided by liquid refrigerant. Such a HVAC system is sometimes called an oil-free system. In the oil-free system, liquid refrigerant can be directed to surfaces of the moving parts for lubrication. The liquid refrigerant on the moving parts may be vaporized, because the refrigerant has a relatively low boiling temperature. During an off-cycle, for example, the liquid refrigerant on the moving parts may be vaporized. When the HVAC system subsequently starts up from an off-cycle, the surfaces of the moving parts may not have sufficient liquid refrigerant to provide lubrication, potentially causing abnormal wear on the moving parts. Improvement can be made to direct liquid refrigerant to the moving parts relatively quickly when, for example, the HVAC system starts up from an off-cycle. 
     The embodiments as disclosed herein describe methods, systems and apparatuses directed to a refrigerant outlet of a condenser that can receive and store liquid refrigerant during, for example, an off-cycle. The stored liquid refrigerant can be directed relatively quickly to, for example, moving parts during the subsequent start-up. The refrigerant outlet may include an outflow pipe and a weir. In some embodiments, the weir may be an annular reservoir surrounding the outflow pipe. In some embodiments, the refrigerant outlet can be positioned below a bottom of the condenser so that liquid refrigerant in the condenser can flow to the weir. The weir may include a port, through which liquid refrigerant in the weir can be directed to, for example, moving parts of the chiller. In some embodiments, the outflow pipe may extend vertically relative to the bottom of the condenser. In some embodiments, a first opening of the outflow pipe may be positioned inside the condenser and may be positioned higher than the bottom of the condenser; while the weir may be positioned lower than the bottom of the condenser. In some embodiments, when the chiller is in an off-cycle, liquid refrigerant in the condenser can flow to and be stored in the weir. During the subsequent start-up, the liquid refrigerant in the weir can be directed relatively quickly to moving parts of the chiller. In some embodiments, such as after start-up and/or during an off cycle, the liquid refrigerant can be preferentially directed to the weir before the liquid refrigerant flowing out of the outflow pipe so that liquid refrigerant may be available in the weir as needed for, for example, lubrication. 
     References are made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration of the embodiments in which the embodiments may be practiced. The term “off-cycle” generally means that a compressor of a HVAC system is not in operation. The term “start-up” generally means that the HVAC starts to operate from an off-cycle. It is to be understood that the terms used herein are for the purpose of describing the figures and embodiments and should not be regarding as limiting the scope of the present application. 
       FIGS. 1A to 1C  illustrate a portion of a condenser  100  of, for example, a chiller system (not shown). As shown in  FIG. 1A , the illustrated condenser  100  is a shell-and-tube type condenser, which may be commonly found in a commercial chiller system. In the illustrated configuration, the condenser  100  has a longitudinal direction L and a vertical direction V. The condenser  100  has a shell  102  that defines an inner space  105 , which has a top  110  and a bottom  120 . The condenser  100  may be configured to condense compressed refrigerant vapor to liquid refrigerant in the space  105 . The liquid refrigerant is typically accumulated on the bottom  120  of the condenser  100 . 
     A refrigerant outlet  130  is attached to the shell  102  on the bottom  120 . In some embodiments, the refrigerant outlet  130  may be attached to the shell  102  at about the lowest point of the shell  102  in the vertical direction V. 
     The refrigerant outlet  130  includes an outflow pipe  135  and an outer wall  136  that surrounds the outflow pipe  135 . The outer wall  136  and an outside surface  137  (see  FIG. 1B ) of the outflow pipe  135  define a weir  138  that surrounds the outflow pipe  135 . In the embodiment shown, the weir  138  is positioned below the bottom  120  of the condenser  100 . The outer wall  136  includes a port  140  that forms fluid communication with the weir  138 . The weir  138  has an opening  142  on the bottom  120 , through which the weir  138  forms fluid communication with the space  105 . (See  FIG. 1B ) 
     The outflow pipe  135  is configured to extend in the vertical direction V and form fluid communication with the space  105 . The outflow pipe  135  has a first opening  135   a  positioned inside the space  105  and a second opening  135   b  positioned outside the space  105 . As illustrated in  FIG. 1A , the first opening  135   a  is configured to be higher than the bottom  120  of the condenser  100  in the vertical direction V, and has a height H 1  relative to the bottom  120  of the condenser  100  in the vertical direction V. In some embodiments, the height H 1  can be about 1 to about 1.3 inches, and can be somewhat higher or lower as may be desired and/or needed. The height H 1  may be configured so that liquid may be preferentially directed toward the weir  138  before flowing out of the outflow pipe  135 . 
       FIG. 1B  is an enlarged sectional view of a portion of the condenser  100  that includes the refrigerant outlet  130 . As illustrated, the outer wall  136  and the outside surface  137  of the outflow pipe  135  define the weir  138 . The weir  138  is in fluid communication with the space  105  independently from the outflow pipe  135 . The outside surface  137  of the outflow pipe  135  and the outer wall  136  have a distance D 1  in the longitudinal direction L as shown. Generally, the larger the distance D 1 , the easier liquid refrigerant can flow into the weir  138 . The distance D 1  can be configured so that liquid refrigerant can flow into the weir  138  relatively easily, or the distance D 1  does not create restriction to the liquid refrigerant flowing into the weir  138 . 
     The port  140  has a diameter D 2 . In some embodiments, the distance D 1  is about the same as the diameter D 2 . 
     As illustrated in  FIG. 1B , the port  140  is positioned higher than a bottom  139  of the weir  138 . The port  140  has a lowest portion  145  in the vertical direction V. The lowest portion  145  is higher than the bottom  139  in the vertical direction V. When the weir  138  contains the liquid refrigerant, precipitates in the liquid refrigerant may accumulate on the bottom  139  of the weir  138 . Positioning the lowest portion  145  of the port  140  higher than the bottom  139  can help reduce the precipitates flowing out of the weir  138  from the port  140 . 
       FIG. 1C  is a top sectional view of the refrigerant outlet  130  along the line  1 C- 1 C in  FIG. 1B . As illustrated, the outflow pipe  135  and the outer wall  136  generally have a circular profile, with the understanding that the outer wall  136  and/or the outflow pipe  135  can have a profile of other shapes. The outflow pipe  135  and the outer wall  136  are generally concentric and define the annular weir  138  surrounding the outflow pipe  135  in the illustrated embodiment. 
     Referring to  FIGS. 1A to 1C , when in operation, liquid refrigerant can accumulate at the bottom  120  of the condenser  100  and can flow to the weir  138 . The liquid refrigerant accumulated in the weir  138  can be directed out of the weir  138  from the port  140  to, for example, a compressor (not shown) to lubricate moving ports of the compressor, such as a bearing of the compressor. 
     The outflow pipe  135  is configured to direct liquid refrigerant out of the condenser  100 . And the refrigerant can be directed toward such as for example an evaporator or an economizer (not shown). The liquid refrigerant can flow from the first end  135   a  to the second end  135   b  of the outflow pipe  135 . Because the first end  135   a  of the outflow pipe  135  is positioned higher than the bottom  120  (e.g. the height H 1  is about 1 inch in  FIG. 1A ), while the weir  138  is positioned lower than the bottom  120  in the vertical direction V, the weir  138  may contain the liquid refrigerant before the liquid refrigerant can flow out of the condenser  100  from the outflow pipe  135 . After a start-up, for example, the liquid refrigerant may be preferentially directed toward the weir  138  before the liquid refrigerant flowing out from the outflow pipe  135 , so that the weir  138  can generally have liquid refrigerant available for, for example, providing lubrication to areas of the system that may have a need. 
     When the HVAC system is in an off-cycle, for example, liquid refrigerant may be emptied from the outflow pipe  135 . The condenser  100  may generally still have some liquid refrigerant condensing during the off-cycle. Because the weir  138  is positioned below the bottom  120 , the weir  138  can receive and store the liquid refrigerant left in the condenser  100  during the off-cycle. When the HVAC system starts up subsequently, the weir  138  can provide liquid refrigerant stored during the off-cycle. During the off-cycle, the weir  138  can function as a liquid refrigerant reservoir. During normal operation condition, the weir  138  can generally receive liquid refrigerant from the condenser and store the liquid refrigerant. 
     It is to be appreciated that the refrigerant outlet  130  may be used with other types of condensers than shell-and-tube condensers. Generally, the refrigerant outlet  130  can be attached to a location of a condenser that can accumulate or have liquid refrigerant during an off-cycle. In some embodiments, a method of providing lubricating liquid refrigerant relatively quickly during start-up may include directing liquid refrigerant out of a condenser during an off-cycle; storing the liquid refrigerant in a reservoir (such as the weir  138  in  FIG. 1A ); and directing the stored liquid refrigerant out of the reservoir during a subsequent start-up. 
     It is to be appreciated that a component of the HVAC system, other than a condenser, that may be able to pool liquid refrigerant during certain operation conditions and/or during the off-cycle may be potentially used as a source of liquid refrigerant for providing lubricating liquid refrigerant. The refrigerant outlet  130  may be configured to be suitably applied to such components, e.g. an evaporator, or other heat exchangers. 
     As illustrated in  FIGS. 1A and 1B , the refrigerant outlet  130  can be an integrated part of the shell  102  of the condenser  100 . This is exemplary.  FIG. 2  illustrates another embodiment of the refrigerant outlet  230  that is attached to a condenser  200 . The condenser  200  has an outlet port  222 . An outer wall  236  of the refrigerant outlet  230  can be removably coupled to the outlet port  222  via, for example, threads  260 .  FIG. 2  also illustrates that distance D 1   a  between an outside surface  237  of the outflow pipe  235  to the outer wall  236  can be smaller than a diameter D 2   a  of a port  240 , which may help pool the refrigerant faster between the outer wall  236  and the outside surface  237  of the outflow pipe  235 . It is to be appreciated that the diameters and distances shown and described herein can be suitably applied to any of the embodiments, configurations shown and described in  FIGS. 1 to 4 . 
     As illustrated in  FIG. 1C , the port  140  can roughly extend along a diameter D 5  of the circular profile of the outer wall  136 . That is, a centerline C 2  of the port  140  generally extend through a center C 1  of the circular profile of the outer wall  136 . This is exemplary.  FIG. 3  illustrates another embodiment of a refrigerant outlet  330 . An outer wall  336  can be not concentric with an outflow pipe  335 . In the orientation as shown in  FIG. 3 , a port  340  of the outer wall  336  is positioned toward a side that is different from the outflow pipe  335  relative to a center C 3  of the outer wall  336  in a longitudinal direction L 3 , so that the outflow pipe  335  and the outer wall  336  may be eccentrically arranged where the port  340  is off-set in the longitudinal direction L 3  relative to a center C 4  of the outflow pipe  335 . 
     As illustrated in  FIGS. 1A and 1B , the outflow pipe  135  is a straight pipe, which has a relatively uniform diameter. This is exemplary. As illustrated in  FIG. 4 , an outflow pipe  435  of a refrigerant outlet  430  may include two sections  435   a  and  435   b  that have different diameters D 3  and D 4  respectively. In some embodiments, the diameter D 3  can be larger than D 4 . In some embodiments, the diameter D 3  can be smaller than D 4  or they can be about the same diameter. 
     Aspects 
     Any of aspects 1 to 6 can be combined with any of aspects 7-17. Any of aspects 7-15 can be combined with any of aspects 16, 17. 
     Aspect 1. A refrigerant outlet of a heat exchanger, comprising: 
     an outflow pipe; 
     an outer wall surrounding the outflow pipe, an outside surface of the outflow pipe and the outer wall define an annular weir surrounding the outflow pipe; and 
     a port on the outer wall in fluid communication with the weir; 
     wherein the outflow pipe has a first end and a second end, the weir has an opening, 
     and the first end is configured to be positioned higher than the opening of the weir when the refrigerant outlet is installed on the heat exchanger. 
     Aspect 2. The refrigerant outlet of aspect 1, wherein the port of the outer wall has a diameter, the outer wall and the outside surface of the outflow pipe has a distance therebetween, and the distance is about the same as the diameter. 
     Aspect 3. The refrigerant outlet of aspects 1-2, wherein the weir has a bottom, the port has a lowest point, and the lowest point is positioned higher than the bottom of the weir when the refrigerant outlet is installed to the condenser. 
     Aspect 4. The refrigerant outlet of aspects 1-3, wherein the refrigerant outflow pipe has a first section with a first diameter and a second section with a second diameter, and the first diameter is different from a second diameter. 
     Aspect 5. The refrigerant outlet of aspects 1-4, wherein the outer wall and the outflow pipe have circular profiles, and the circular profile of the outer wall and the circular profile of the outflow pipe are concentrically positioned. 
     Aspect 6. The refrigerant outlet of aspects 1-5, wherein the outer wall and the outflow pipe have circular profiles, and the circular profile of the outer wall the circular profile of the outflow pipe are eccentrically positioned. 
     Aspect 7. A heat exchanger, comprising: 
     a shell having a bottom, the shell defining a space; and 
     a refrigerant outlet installed on the bottom of the shell; 
     wherein the refrigerant outlet includes an outflow pipe; 
     an outer wall surrounding the outflow pipe, the outflow pipe and an outside surface of the outer wall define an annular weir surrounding the outflow pipe; 
     a port on the outer wall in fluid communication with the weir; the outflow pipe has a first end and a second end, the first end is configured to be positioned inside the shell; the weir has an opening in fluid communication with the space; and the first end is configured to be positioned higher than the opening of the weir. 
     Aspect 8. The heat exchanger of aspect 7, wherein the port of the outer wall has a diameter, the outer wall and the outside surface of the outflow pipe has a distance therebetween, and the distance is about the same as the diameter. 
     Aspect 9. The heat exchanger of aspects 7-8, wherein the weir has a bottom, the port has a lowest point, and the lowest point is positioned higher than the bottom of the weir. 
     Aspect 10. The heat exchanger of aspects 7-9, wherein the refrigerant outflow pipe has a first section with a first diameter and a second section with a second diameter, and the first diameter is different from a second diameter. 
     Aspect 11. The heat exchanger of aspects 7-10, wherein the outer wall and the outflow pipe have circular profiles, and the circular profile of the outer wall and the circular profile of the outflow pipe are concentrically positioned. 
     Aspect 12. The heat exchanger of aspects 7-11, wherein the outer wall and the outflow pipe have circular profiles, and the circular profile of the outer wall the circular profile of the outflow pipe are eccentrically positioned. 
     Aspect 13. The heat exchanger of aspects 7-12, wherein the outflow pipe has a first section with a first diameter, and a second section with a second diameter, and the first diameter is different from the second diameter. 
     Aspect 14. The heat exchanger of aspect 13, wherein the first diameter is larger than the second diameter. 
     Aspect 15. The heat exchanger of aspects 13-14, wherein the first section is positioned inside the shell of the heat exchanger. 
     Aspect 16. A method of providing liquid refrigerant in a HVAC system, comprising: 
     directing liquid refrigerant out of a condenser into a reservoir during an off-cycle; 
     storing the liquid refrigerant in the reservoir; and 
     directing the liquid refrigerant stored in the reservoir out of the reservoir for lubrication during the HVAC system start-up. 
     Aspect 17. The method of providing liquid refrigerant in a HVAC system of aspect 16, further comprising: 
     after start-up, directing the liquid refrigerant preferentially toward the reservoir before the liquid refrigerant flows out of the condenser. 
     With regard to the foregoing 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.