Abstract:
A condenser, for cooling a gas flow containing a vapor to promote condensation of the vapor, has a generally cylindrical chamber. Gas is admitted at one end of the chamber and is given a swirl component of velocity. The gas then travels axially along the length of the chamber, and passes radially through poles into the bore of a separator. The swirl velocity of the gas flow tends to through water droplets radially outwards, where they can drain down the inside of a casing defining the chamber. The separator can include a skirt portion separating the main chamber from a water collection compartment. Cooling to cause condensation is provided by an external jacket, preferably having a coolant flowing through it in a helical fashion.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to a condenser. More particularly, the present invention relates to a condenser for dehumidifying gases. 
     BACKGROUND OF THE INVENTION 
     There are a variety of devices used to condense water out of a gas stream in domestic and industrial applications. Examples of known condenser devices include tube and shell heat exchangers, plate type heat exchangers, etc. 
     One commonly known type of condenser employs bundles of tubes located inside an enclosure. Typically, the enclosure generally has a hollow cylindrical body with a gas inlet and a gas outlet. Gas containing high humidity flows through the chamber of the enclosure and comes into contact with the tube surfaces. Coolant runs through the tubes while moist gas flows over the outer surfaces of the tubes to exchange heat indirectly with the coolant. Water condenses out of the moist gas onto the surface of tubes. The coolant and gas may either flow in substantially same direction, known as “parallel flow”, or in opposite direction, known as “counter flow”. 
     There are variations of these condensers. In some of them, the bundles of tubes are arranged vertically while in others, the tubes are horizontal. In order to enlarge the heat exchange area, the tubes may be in a bent form (U-shape or serpentine shape). The tubes may also take coil or helical shapes. However, in order to increase the flow path and contact area between the gas and the coolant the device has to be large. The efficiency of heat exchange between the surface and the gas depends on the flow rate of gas and coolant. In order to achieve better heat exchange results, the flow rate has to be sufficiently large, which may impact or require ancillary equipment, such as a pump, a compressor, etc. This significantly reduces the system efficiency. Hence, all these variants tend to be bulky and suffer from low heat exchange efficiency. 
     Therefore, there remains a need for a compact, efficient condenser which is operable with relatively low flow rate of coolant and gas to be dehumidified. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided a condenser, for cooling vapor contained in a gas flow, the condenser comprising: 
     a chamber having a generally circular cross-section about an axis thereof and adapted to be mounted with the axis substantially vertical; 
     a gas inlet opening into one end of the chamber, for supply of gas to one end of the chamber, and a gas outlet opening into the chamber, for discharge of gas from the chamber; 
     means for imparting a swirl component of velocity to the gas flow supplied to the chamber through the gas inlet and mounted adjacent said one end of the chamber, the arrangement being such that gas flows from one end of the chamber to the other end thereof; 
     means for cooling the chamber to thereby remove heat therefrom to promote condensation of the vapor; and 
     wherein the means from imparting a swirl component of velocity to the gas flow comprises at least one of an arc-shaped gas compartment adjacent the gas inlet and a deflector vane. 
     In accordance with a further aspect of the present invention, there is provided, a condenser for cooling vapor contained in a gas flow, the condenser comprising: 
     a chamber having a generally circular cross-section about an axis thereof and adapted to be mounted with the axis substantially vertical; 
     a gas inlet opening into one, upper end of the chamber, for supply of gas to one end of the chamber, and a gas outlet opening into the chamber, for discharge of gas from the chamber; 
     means for imparting a swirl component of velocity to the gas flow supplied to the chamber through the gas inlet and mounted adjacent said one end of the chamber, the arrangement being such that gas flows from one end of the chamber to the other end thereof; and 
     means for cooling the chamber to thereby remove heat therefrom to promote condensation of the vapor; 
     wherein the chamber provides for unobstructed downward movement of condensate towards the lower end thereof. 
     Another aspect of the present invention provides a method of cooling a gas flow containing a vapor, to promote condensation of the vapor, the method comprising the steps of: 
     supplying gas containing moisture to a chamber having a generally circular cross-section, applying a swirl component of velocity to the gas flow and causing the gas to flow axially from one end of the chamber to the other with a helical path including the swirl component of flow; 
     cooling the chamber to withdraw heat from the gas and promote condensation of the vapor; 
     mounting the chamber substantially vertically, whereby condensed vapor runs vertically down the inside of the chamber; 
     withdrawing gas, depleted in the vapor, along the axis of the chamber. 
     The present invention provides a compact and effective condenser. The design of arc shaped chamber, deflector vane increases the disturbance of gas flow and hence increases the heat exchange efficiency. The helical flow path of coolant further provides sufficient heat exchange between the gas and the coolant resulting in high efficiency of water separation from the gas. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made to the accompanying drawings, which show, by way of example, preferred embodiments of the present invention: 
     FIG. 1 is a perspective view illustrating a condenser in accordance with the present invention; 
     FIG. 2 is an elevation view illustrating the condenser in accordance with the present invention; 
     FIG. 3 is a perspective sectional view illustrating the condenser in accordance with the present invention along line A—A in FIG. 2; 
     FIG. 4 is an elevational and sectional view illustrating the condenser in accordance with the present invention along line A—A in FIG. 2; 
     FIG. 5 is a perspective view illustrating a head portion of the condenser in accordance with the present invention; 
     FIG. 6 is a plan section view illustrating the head portion of the condenser in accordance with the present invention along line B—B in FIG. 5; 
     FIG. 7 is a perspective section view illustrating the head portion of the condenser in accordance with the present invention along line C—C in FIG. 6; 
     FIG. 8 is a perspective of a deflector of the condenser in accordance with the present invention; 
     FIG. 9 is a longitudinal sectional view of the deflector of the condenser in accordance with the present invention; 
     FIG. 10 is a perspective view of a deflector vane of the condenser in accordance with the present invention; 
     FIG. 11 is a sectional view of the deflector vane of the condenser in accordance with the present invention; 
     FIG. 12 is a perspective sectional view of an outer casing of the condenser in accordance with the present invention; 
     FIG. 13 is a longitudinal sectional view of the outer casing of the condenser in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The features and advantages of the present invention will become more apparent in light of the following detailed description of preferred embodiments thereof. 
     FIGS. 1 to  4  show the condenser  10  of the present invention. Hereinafter, the present invention will be described by way of its application in dehumidifying air using water as coolant. It should be appreciated, however, that the present invention may also be employed to dehumidify other gases or fluids and to exchange heat, and that coolants other than water can be used. 
     The condenser  10  of the present invention generally consists of a casing  20  and a head portion  30 . In operation, the condenser  10  is placed in substantially vertical position with the head portion  30  on top of the casing  20 . As shown in FIG. 1, the casing  20  of the condenser  10  is generally cylindrical in shape and comprises (with reference to FIGS. 3 and 4) an outer casing  80  and an inner casing  90 , which defines a chamber  40 . The inner casing  90  and the outer casing  80  is disposed in coaxial relation and defines an annular space  100  therebetween. The inner casing  90  and the outer casing  80  are welded together at the top ends and bottom ends thereof. The outer casing  80  is provided with a coolant inlet  22  and a coolant outlet  24  located perpendicular to the axis of the casing  20 . The coolant inlet  22  is located adjacent to the bottom of the casing  20  while the coolant outlet  24  is located adjacent to the head portion  30 . The bottom end of the casing  20  is closed by a cap  28 . A water discharge port  26  is provided on the cap  28  to discharge the water condensed from the gas out of the chamber  40  thereof. 
     The head portion  30  of the condenser  10  comprises a semicircular portion  36  and a transversely extending portion  38 . A gas inlet  32  and a gas outlet  34  are provided on an end wall  35  of the transversely extending portion  38 . A separator  50  (FIGS. 8 and 9) and a deflector vane  60  (FIGS. 10 and 11) are disposed inside the chamber  40  of the casing  20 . The deflector vane  60  facilitates the distribution of the gas into the chamber  40  in a desired flow pattern. The separator  50  permits the dehumidified gas to flow out of the chamber  40  and separates the gas from condensed water. The assembly of the casing  20 , head portion  30 , the separator  50  and the deflector vane  60  will be described in more detail below. 
     Now, reference will be made to FIGS. 5 to  7 , which show the head portion  30  of the condenser  10 . The head portion  30  has a circular open end  70  at the bottom face  71  thereof. A rim  72  is provided around the edge of the circular open end  70 . The center of the open end is provided with a bore  76  which is in fluid communication with the gas outlet  34 . The side wall  74  of the bore  76  separates the bore  76  from the rest of the open end  70 , forming an arc shaped compartment  78 . The end face  73  of the bore  76  and side wall  74  are recessed from the bottom face  71  of the head portion  30 . The arc shaped compartment  78  is in fluid communication with the gas inlet  32 . As can be best seen in FIG. 4, a female thread  77  is provided adjacent the bottom end of the bore  76  for connection with the separator  50 . 
     FIGS. 8 and 9 illustrate the separator  50  of the condenser  10 . The separator  50  is generally cylindrical in shape with a skirt portion  52  at the bottom end thereof. The separator  50  has a central portion  51  and a reduced diameter portion  56  at the top end thereof. The reduced diameter portion  56  forms a step  59  with the central portion  51 . A male thread  53  is provided on the outer wall of the reduced diameter portion  56 . The upper end of the male thread  53  is used for connection to the female thread  77  in the bore  76  of the head portion  30 , and hence mounting the separator  50  onto the head portion  30 . The rest of the male thread  53  is used for connection to the deflector vane  60 . 
     The separator  50  has a bore  54  extending axially from the top end of the reduced diameter portion  56  to the bottom wall  49  of the central portion  51 . In this particular embodiment, the bore  54  has a reduced diameter portion  44  axially extending from the top end of the reduced diameter portion  56  to an axial position substantially corresponding to the step  59 . However, it is to be understood that the bore  54  does not necessarily have such a reduced diameter portion  44 . 
     A plurality of through holes extending traverse to the axis of the separator  50  are provided on the side wall of the central portion  51  of the separator  50 . In this example, six through holes  55  are provided evenly around the side wall of the central portion  51  in an axial position adjacent to the bottom end of the central portion  51 . In addition, four through holes  57  are provided evenly around the side wall of the central portion  51  in an axial position adjacent to the top end of the central portion  51 . The through holes fluidly communicate the bore  54  and the space outside the side wall of the separator  50 . 
     A skirt portion  52  extends radially outwardly and downwardly from the bottom wall  49  of the central portion  51 . The diameter of the skirt portion  52  is slightly smaller than the inner diameter of the inner casing  90  to allow water to flow between them. The skirt portion  52  inclines downwardly to facilitate the flow of the condensed water. A plurality of notches  58  are provided around the edge of the skirt portion  52  to further facilitate the drip down of the condensed water into a water collection compartment  53  defined between the skirt portion  52  and the cap  28 . Thus, the inner casing  90  encloses both the main chamber  40  and the water collection compartment  53 . 
     As shown in FIGS. 3 and 4, a deflector vane  60  is mounted around the reduced diameter portion  56  of the separator  50 . The deflector vane  60  is shown more clearly in FIGS. 10 and 11. The deflector vane  60  has a truncated conical shaped portion  62 . A plurality of vanes  64  are provided around the larger end of the truncated conical shaped portion  62 . The vanes  64  are arranged such that helically inclined gaps are formed between adjacent vanes  64 . The gaps are inclined along substantially same helical direction. The outer diameter of the vanes  64  is slightly smaller than the inner diameter of the inner casing  90  to allow flow through of gas and easy assembly. The deflector vane  60  has a bore  65  in the center thereof. The bore  65  extends axially throughout the length of the deflector vane  60  and has a female thread  66 . The female thread  66  connects the deflector vane  60  to the separator  50  in cooperation with the male thread  53  on the reduced diameter portion  56  of the separator  50 . When the deflector vane  60  is mounted onto the separator  50 , the bottom face  68  of the deflector vane  60  abuts against the step  59  of the separator  50  and the top face  69  abuts against the bottom face  73  of the side wall  74  on the head portion  30 , as can be seen in FIGS. 3 and 4. Thus, the chamber  40  largely comprises an unobstructed annular spaced between the deflector vane  60 , the inner casing  90 , the separator  50  and the skirt portion  52 , through which the gas flows without being subject to any other elements affecting gas velocity or direction. 
     Now, reference will be made to FIGS. 12 and 13, which show the outer casing  80  of the condenser  10 . The outer case  80  is generally cylindrical in shape with two open ends  88  and  89 . On the side wall, a coolant inlet port  82  is provided adjacent the bottom end of the outer casing  80  and a coolant outlet port  84  is provided adjacent the top end thereof. The top edge of the outer casing  80  is provided with a reduced diameter portion  83  so that the reduced diameter portion  83  fits into the rim  72  of the head portion  30  in assembly. During assembly, the rim  72  and the reduced diameter portion  83  jointed are welded together to prevent any leakage of gas to be dehumidified between the head portion  30  and the casing  20 . 
     A rib  86  is provided on the inner wall of the outer casing  80 . The rib  86  starts from the coolant inlet port  82 , runs helically upwardly around the inner wall of the outer casing  80  and ends at a position adjacent to the top end of the outer casing  80 . The helical rib  86  protrudes from the inner wall of the outer casing  80  such that when the inner casing  90  and outer casing  80  are welded together, the rib  86  substantially abuts against the outer wall of the inner casing  90 , thereby separating the annular space  100  between the inner casing  90  and the outer casing  80  into one continuous helical channel  110 , as shown in FIGS. 3 and 4. The bottom end  88  of the outer casing  80  is provided with a female thread  85  for connection with a cap  28 . It can be seen from FIGS. 3 and 4 that the inner casing  90  is generally cylindrical in shape. It is to be understood that the inclination and pitch of the helical rib  86 , and hence that of the helical channel  110  may vary as desired, and there can be more than one helical channel. 
     Stilling referring to FIGS. 3 and 4, the cap  28  closes the bottom end of the casing  20  through thread connection. Therefore, the chamber  40  is defined therein. A water level detector  42  can be mounted on the cap  28  to monitor the level of the condensed water in the water collection compartment  53 . When the condensed water reaches a certain level, the water discharge port  26  is opened to discharge water out of the chamber  40 . This can be done manually or automatically. 
     In operation, gas to be dehumidified flows into the condenser  10  through the gas inlet  32 . From the gas inlet  32 , the gas flows through the arc shaped chamber  78 . The disturbance or turbulence of the gas flow increases as the direction of gas flow changes. In addition, since the vane  64  of the deflector vane  60  substantially closes the circular open end  70  of the head portion  30  except for a plurality of gaps between adjacent vanes  64 , the gas flows into the chamber  40  through said plurality of helically inclined gaps. Therefore, a vortex is formed in the gas flowing into the chamber  40 , i.e. a substantial swirl component of velocity is imparted to the gas flow. The gas flows downwardly in a swirling pattern in the chamber  40  around the separator  50 . 
     Simultaneously, a coolant, usually water, is supplied from the coolant inlet  22  near the bottom of the casing  20 . From the coolant inlet  22 , the coolant flows into the annular space  100  between the inner casing  90  and the outer casing  80 . From here, coolant flows upwardly along the helical channel  110  and flows out of the annular space  100  from the coolant outlet  24  adjacent the top end of the casing  20 , i.e. the coolant flow is countercurrent in the axial direction. 
     In the chamber  40 , the gas is cooled on the surface of the inner casing  90  and hence water is condensed. The dehumidified gas then flows through the plurality of through holes  55  and  57  into the bore  54  of the separator  50 . From here, the gas flows along the channel formed by the bore  54  of the separator  50 , and the bore  76  of the head portion  30 . Then the dehumidified gas flows out of the condenser  10  through the gas outlet  34 . The swirling flow of the gas and the helical flow path of coolant provide sufficient heat exchange between the gas and the coolant, resulting in high efficiency of water separation from the gas. The swirling flow also promotes separation of water droplets from the gas flow, and should prevent water droplets being entrained in the radially inward flow of gas into the through holes  55 ,  57 . 
     Condensed water flows down along the inner wall of the inner casing  90  and the skirt portion  52  of the separator  50 , down to the bottom of the water collection compartment  53 . As mentioned before, condensed water is discharged when it reaches a certain level. 
     It should also be appreciated that the present invention is not limited to the embodiment disclosed herein. It can be anticipated that those having ordinary skills in the art can make various modification to the embodiments disclosed herein after learning the teaching of the present invention. For example, the number and arrangement of components in the system might be different, different elements might be used to achieve the same specific function. However, these modifications should be considered to fall into the protection scope of the invention as defined in the following claims.