US 3566615 A
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Description (OCR text may contain errors)
March'Z, 1971 RQEDER, JR 3,566,615
HEAT EXCHANGER WITH ROLLED-IN CAPILLARY FOR REFRIGERATION APPARATUS Filed April 5, 1969 f J9 J6 I 24 jnUenZ 07": Jo/zw/ Raeder; J2,
United States Patent HEAT EXCHANGER WITH ROLLED-IN CAPILLARY FOR REFRIGERATION APPARATUS John Roeder, Jr., Benton Harbor, Mich., assignor to Whirlpool Corporation Filed Apr. 3, 1969, Ser. No. 813,187 Int. Cl. Fb 41/06 US. Cl. 62-511 10 Claims ABSTRACT OF THE DISCLOSURE A fluid flow structure wherein a first fluid flow duct is provided with an external, outwardly opening groove. The groove is covered by an outer element which, in the illustrated embodiment, comprises an outer tube. The groove is made to be small in cross-section so as to define a capillary restrictor relative to fluid flow therethrough. The restriction of flow is adjusted by suitably deforming the outer tube overlying the groove so as to adjustably decrease the cross-section of the capillary restrictor passage. The fluid flow structure may be used in a refrigeration system for providing heat exchange between refrigerant fluid delivered from the evaporator through the first tube and refrigerant fluid delivered from a condenser to the evaporator through the capillary passage.
BACKGROUND OF THE INVENTION Field of the invention This invention relates to fluid flow structures and in particular to heat exchangers such as used in refrigeration apparatus.
Description of the prior art In conventional refrigeration systems, restriction of the flow of refrigerant to the evaporator is provided by means of a capillary duct having a small cross-section. Further, the capillary duct is connected through a heat exchanger to the evaporator with a heat exchanger defining a duct for delivering refrigerant from the evaporator for subsequent recycling. A conventional method of adjusting the capillary restriction is to vary the length of the capillary tube. Such a method of adjusting the restriction has the obvious disadvantage of requiring disconnection and reconnection of the capillary restrictor after determining a need for such adjustment.
Another problem found in the conventional refrigeration system structures is the space requirements for providing separate capillary and heat exchanger devices arranged in series in the system. The known devices further have the disadvantage of relatively high cost.
SUMMARY OF THE INVENTION The present invention comprehends an improved fluid flow structure which eliminates the disadvantages of the above discussed known structures. More specifically the present invention comprehends a fluid flow structure including wall means defining a flow passage, the wall means further defining an outwardly opening groove of small cross-section, a cover element overlying the groove and sealed to the wall means, the overlaid groove defining a second fluid flow passage providing capillary restriction of fluid flow therethrough, means defining an inlet to the second flow passage, and means spaced from the inlet defining an outlet for the second flow passage.
Further, more specifically, the invention comprehends the provision of such a fluid flow structure for use as a heat exchanger in a refrigeration system having an evaporator and a condenser, the heat exchanger comprising a first tube, means for connecting the first tube to the evap- Patented Mar. 2, 1971 "ice orator for conducting refrigerant from the evaporator, the wall of the first tube having an indented small crosssection groove therein, a second tube encircling the first tube and covering said groove whereby the covered groove defines a capillary passage, and means for connecting the capillary passage between the condenser and the evaporator for conducting refrigerant from the condenser to the evaporator, the first tube being formed of a thermally conductive material whereby refrigerant being delivered through the capillary passage is cooled by refrigerant flowing through the first tube.
The invention comprehends adjusting the restriction provided by the capillary restrictor by suitably deforming the outer cover element so as to project inwardly into the groove. The deformation of the cover element can be readily effected after assembly of the fluid flow structure and by the simple expedient of rolling a groove in the cover element overlying the groove of the inner tube, the depth of the rolled-in outer groove being controlled to provide the desired increased restriction of fluid flow through the covered groove.
In the illustrated embodiment, the inner tube or duct and outer cover element comprise concentric cylindrical tubes having a relatively snug fit with the groove in the inner tube being helical and with suitable inlet and outlet structures provided in the outer tube to permit flow of fluid therethrough.
BRIEF DESCRIPTION OF THE DRAVVI NGS Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawing wherein:
FIG. 1 is a diametric section of a fluid flow structure embodying the invention in a portion of a refrigeration system including an evaporator and a condenser;
FIG. 2 is a transverse section thereof; and
FIG. 3 is a fragmentary diametric section of the fluid flow structure illustrating the arrangement thereof as adjusting for providing a preselected capillary restriction.
DESCRIPTION OF THE PREFERRED EMBODIMENT In the exemplary embodiment of the invention as disclosed in the drawing, a refrigeration system generally designated 10 is shown to comprise a fluid flow structure generally designated -11 defining a heat exchanger for providing precooled refrigerant liquid to an evaporator 12 from a condenser 13. The liquid refrigerant is cooled by heat exchange with the refrigerant delivered from the evaporator !12 flowing in counter-current flow through the heat exchanger 11.
As discussed above, the fluid flow'structure 11 is extremely simple in construction while providing the highly desirable heat exchange between the liquid refrigerant delivered to the evaporator and the refrigerant delivered from the evaporator which may be in the form of vapor and purge liquid. As best seen in FIG. 1, the fluid flow structure 11 comprises a first tube 14 having an inlet end 15 and an outlet end 16. The tube is defined by wall means provided with an indented groove 17, which in the illustrated embodiment, is helical and extends from adjacent inlet 15 to adjacent inlet 16. The tube 14 is preferably formed of a material having high thermal conductivity such as metal and illustratively may be formed of steel, brass, aluminum, etc. The groove 17 may be formed in the tube 14 as by a conventional rolling process well known to those skilled in the art. The cross-section of the groove, as shown in FIG. 1, is relatively small as compared with the cross-section of the tube 14.
Concentrically surrounding the inner tube 14 is a second or outer tube 18 which may have a relatively snug fit with the inner tube, and which defines a cover element overlying the groove 17. The covered groove thusly defines a capillary restrictor passage 19. As shown in FIG. 1, the end of the tube 18 may be welded to the inner tube 14 adjacent inlet 15 and the end 21 of the tube 18 may be welded to the tube adjacent the outlet 16 whereby the tube 18 effectively sealingly covers the groove 17 to define the capillary passage 19.
The outer tube 18 may be provided with an opening 22 defining an inlet opening to the capillary passage 19. A suitable connector 23 may be secured to the tube at opening 22 for delivering refrigerant from the condenser 13 to the capillary passage 19. A similar opening 24 is provided in the opposite end of the tube 18 to define an outlet opening for delivering the refrigerant from the restrictor passage 19 through an outlet connector 25 to the evaporator 12.
As the inner tube 14 is formed of a material having high thermal conductivity, heat exchange readily occurs between the refrigerant flowing through the restrictor passage 19 to the evaporator and the refrigerant flowing from the evaporator through the inner tube 14. Thus, the refrigerant being delivered to the evaporator 12 is precooled for improved efficiency of cooling in the evaporator. Illustratively, the refrigerant may comprise liquid ammonia where the refrigeration system comprises a conventional absorption refrigeration system.
Thus fluid flow structure 11 is extremely simple and economical of construction while providing the highly desirable dual function of precooling of the refrigerant being delivered to the evaporator and providing capillary restriction thereof for control of the fluid pressures in the system.
The fluid flow structure provides a further advantage over the conventional fluid flow structures in such refrigerator systems in that adjustment of the restriction of flow from the capillary passage 13 may be readily effected by simple deformation of the outer tube to cause at least a portion thereof to project into the capillary passage 19, as shown at 26 in FIG. 3, whereby the crosssection of the flow passage 19 is adjustably reduced to a desired preselected value. The deformation of the outer tube may be substantially along the entire length of the passage 19 or may be at preselected portions thereof as desired. Where the passage is helical, the deformation may comprise a helical groove substantially coincident with the passage 19. The deformation may be readily provided in the outer tube 18 as by a conventional rolling operation.
Thus, at least a portion of the passage 19 comprises a capillary restrictor in heat exchange relationship with the refrigerant delivered from the evaporator. Accurate control of the amount of restriction is readily obtained in the improved simplified fluid flow structure by virtue of the readily controllable deformation of the outer tube relative to the groove 17.
The invention has been illustrated in connection with a refrigerator system wherein the fluid flow structure comprises a heat exchanger for controlling refrigerant delivered to and from the evaporator. As will be obvious to those skilled in the art, the fluid flow structure 11 may equally well be utilized as an evaporator having integral capillary passage means, as well as other similar heat exchanger arrangements.
Having described my invention as related to the embodiment' shown in the accompanying drawings, it is my intention that the invention be not limited by any of the details of description, unless otherwise specified, but rather to be construed broadly within its spirit and scope as set out in the accompanying claims.
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A refrigerant fluid flow structure comprising: wall means defining a first refrigerant fluid flow passage, said wall means further defining an outwardly opening groove of small cross-section; a cover element overlying said groove and sealed to said wall means, the overlaid groove defining a second refrigerant fluid flow passage having an accurately preselected configuration providing a preselected capillary restriction of fluid fiow therethrough, said cover element facially engaging said wall means over a major portion of the confronting surfaces thereof; means defining an inlet to said second fluid flow passage; and means spaced from said inlet defining an outlet for said second flow passage.
2. The fluid flow structure of claim 1 wherein said cover element defines an inwardly projecting portion extending adjustedly into said groove to provide a preselected adjusted restriction of the fluid flow through said second fluid flow passage.
3. The fluid flow structure of claim 1 wherein said wall means is formed of thermally conductive material providing high heat transfer between fluids flowing through said first and second fluid flow passages.
4. The fluid flow structure of claim 1 wherein said wall means comprises a first tube, and said cover element comprises a second tube concentrically encircling said first tube.
5. The fluid flow structure of claim 1 wherein said groove comprises a helical groove.
6. The fluid flow structure of claim 1 wherein said second flow passage has a substantially constant crosssection throughout its length whereby substantially the entire second flow passage comprises a capillary restrictor.
7. In a refrigerator system having an evaporator and a condenser, a heat exchanger comprising:
a first tube;
means for connecting the first tube to the evaporator for conducting refrigerant from the evaporator, said first tube having an indented small cross-section groove therein;
a second tube surrounding said first tube and covering said groove whereby said covered groove defines a capillary passage;
and means for connecting said capillary passage between said condenser and said evaporator for conducting refrigerant from the condenser to the evaporator, said first tube being formed of a thermally conductive material whereby refrigerant being delivered through the capillary passage is cooled by refrigerant flowing through said first tube.
8. The heat exchanger of claim 7 wherein said groove comprises a rolled groove.
9. The heat exchanger of the claim 7 wherein said second tube is adjustably deformed into said groove to provide adjustable flow restriction of said refrigerant being delivered to said evaporator.
10. The heat exchanger of claim 7 wherein said second tube is adjustably deformed into said groove along substantially the entire length of said groove.
References Cited UNITED STATES PATENTS 1,797,014 3/1931 Nichols 156 1,957,828 5/1934 Greenwald 62-5l1 2,145,774 1/1939 Muffly 62513 3,468,371 9/1969 Menze 165-l56 MEYER PERLIN, Primary Examiner US. Cl. X.R.