Evaporator having integrated pulse wave atomizer expansion device

Abstract

An evaporator for use in a refrigeration system includes one or more Coanda evaporation chambers having an integrated, internal expansion device. The internal expansion device is a linear atomization tube having a plurality of ejection holes arranged in a series of spiral rows. Liquid refrigerant introduced into the linear atomization to is ejected onto the inner wall of the Coanda evaporation chamber, covering it completely with a thin layer of liquid refrigerant. Liquid refrigerant is fed to the linear atomization device in a series of rapid pulses.

Claims

1. An evaporator for a refrigeration system having an integrated expansion device comprising: at least one elongate evaporator chamber having an airfoil-shaped cross section and extending between an inlet manifold at a proximal end and an outlet manifold at a distal end; a plurality of vapor outlet holes near a top of the distal end of the evaporator chamber and a plurality of oil outlet holes near a bottom of the distal end of the evaporator chamber, wherein the outlet holes provide fluid communication between the evaporator and the outlet manifold; a linear atomizer comprising a tube having a plurality of substantially evenly spaced holes extending through a center of the at least one elongate evaporator chamber; a pulse injector feeding liquid refrigerant to the evaporator chamber in a series of rapid pulses; wherein the airfoil-shaped cross section of the elongate evaporator chamber induces a Coanda effect on air blown across the elongate evaporation chamber by a fan.

2. The evaporator for a refrigeration system having an integrated expansion device of claim 1 wherein the linear atomizer has a progressively smaller diameter as it travels from the proximal end to the distal end of the at least one elongate evaporator chamber.

3. The evaporator for a refrigeration system having an integrated expansion device of claim 1 further comprising a plurality of fins on the exterior of the at least one elongate evaporator chamber perpendicular to a length of the at least one elongate evaporator chamber defined by the proximal end and the distal end of the elongate evaporator chamber.

4. The evaporator for a refrigeration system having an integrated expansion device of claim 1 wherein the distal end of the elongate evaporator chamber includes a plurality of vapor outlet holes near a top of the elongate evaporator chamber and a plurality of oil outlet holes near a bottom of the elongate evaporator chamber.

5. The evaporator for a refrigeration system having an integrated expansion device of claim 1 wherein the at least one elongate evaporator chamber comprises a plurality of the elongate evaporator chambers, each of which may be individually fluidly closed so that refrigerant cannot flow from the inlet and outlet manifolds.

6. The evaporator for a refrigeration system having an integrated expansion device of claim 1 further comprising an electronically modulating valve that controls flow into the inlet manifold, thereby allowing an operator to attenuate liquid refrigerant pressure in response to changes in a refrigeration system load.

7. The evaporator for a refrigeration system having an integrated expansion device of claim 1 wherein the refrigeration system includes a compressor and a condensor, said device interposed internally in evaporator and downstream from the condenser.

8. The evaporator for a refrigeration system having an integrated expansion device of claim 1 wherein the pulse injector is a pulse wave device operated by a piezo electric valve actuator capable of operating at cycles of less than one second.

9. The evaporator for a refrigeration system having an integrated expansion device of claim 1 wherein the outlet manifold includes a plate heat exchanger and said plate heat exchanger is capable of having liquid refrigerant pumped through the plate heat exchanger prior to entering the inlet manifold.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

(2) FIG. 1 is a diagram of a typical prior art refrigeration system;

(3) FIG. 2 is a perspective view of an evaporator for a refrigeration system in accordance with the principles of the invention;

(4) FIG. 3 is a cutaway view of a Coanda evaporation chamber in accordance with principles of the invention;

(5) FIG. 4 is a perspective view of an alternative embodiment of a Coanda evaporation chamber in accordance with principles of the invention;

(6) FIG. 5 is a plan view of a distal end of an alternative embodiment of a Coanda evaporation chamber in accordance with the principles of the invention;

(7) FIG. 6 is a perspective view of an alternative embodiment of a Coanda evaporation chamber in accordance with principles of the invention;

(8) FIG. 7 is a front elevation view of an alternative embodiment of a Coanda evaporation chamber in accordance with principles of the invention;

(9) FIG. 8 is a perspective view of a linear atomization tube in accordance with principles of the invention;

(10) FIG. 9 is a perspective view of an alternative embodiment of a linear atomization tube in accordance with the principles of the invention;

(11) FIG. 10 is a perspective view of another alternative embodiment of an evaporator for a refrigeration system in accordance with the principles of the invention;

(12) FIG. 11 is a perspective view of another alternative embodiment of an evaporator for a refrigerator system in accordance with the principles of the invention;

(13) FIG. 12 is a perspective view of another alternative embodiment of an evaporator for a refrigerator system in accordance with the principles of the invention;

(14) FIG. 13 is a perspective view of a plate heat exchanger affixed to an outlet manifold for an evaporator for a refrigeration system in accordance with principles of the invention;

(15) FIG. 14 is a cutaway view of an outlet manifold for an evaporator for a refrigeration system in accordance with principles of the invention.

DETAILED DESCRIPTION

(16) The invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.

(17) The disclosed subject matter is described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the various embodiments of the subject disclosure. It may be evident, however, that the disclosed subject matter may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing the various embodiments herein.

(18) Unless otherwise indicated, all numbers expressing quantities of ingredients, dimensions reaction conditions and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about”. The term “a” or “an” as used herein means “at least one” unless specified otherwise. In this specification and the claims, the use of the singular includes the plural unless specifically stated otherwise. In addition, use of “or” means “and/or” unless stated otherwise. Moreover, the use of the term “including”, as well as other forms, such as “includes” and “included”, is not limiting. Also, terms such as “element” or “component” encompass both elements and components comprising one unit and elements and components that comprise more than one unit unless specifically stated otherwise.

(19) As used herein, unless otherwise indicated, either explicitly or implicitly due to the context, the term “Coanda evaporation chamber” refers generally to an elongate evaporation chamber having a cross-sectional shape that induces a Coanda effect on a fluid passing over the outside of the evaporation chamber in a direction parallel to the cross-section and perpendicular to the length of the evaporation chamber. The evaporator chamber may have a pure elliptic cross-section or a cross-section of an ellipse where one or both ends of the ellipse or pointed, a cross-sectional shape of an airfoil, or other configuration improving laminar airflow by means of a Coanda effect. The length of a Coanda evaporation chamber may be substantially straight, curved or serpentine as is known in the art.

(20) Various embodiments of the disclosure could also include permutations of the various elements recited in the claims as if each dependent claim was a multiple dependent claim incorporating the limitations of each of the preceding dependent claims as well as the independent claims. Such permutations are expressly within the scope of this disclosure.

(21) The expansion device in accordance with the principles of the invention, instead of being upstream from the evaporation chamber is integrated into the evaporation chamber and comprises an atomization system. One atomization system in accordance with the principles of the invention may be referred to as an LRAD (Linear Refrigerant Atomizer Design), and is formed from a tube inside a Coanda evaporation chamber extending along the length of the evaporation chamber and positioned substantially centrally within the evaporation chamber. The linear atomization tube in accordance with the principles of the invention provides an improved rate of heat transfer in the evaporation chamber by atomizing the refrigerant into small droplets, or particles, and spraying them evenly onto the inner wall of the evaporator chamber. As a result, substantially all of refrigerant vaporizes almost instantly upon contact with the inner wall. This saturated vapor then (expansion) leaves the evaporator as a vapor, which is not necessarily superheated.

(22) FIGS. 2 and 3 shows an exemplary evaporator 40 in accordance with the principles of the invention having an inlet manifold 42 which distributes liquid refrigerant into eight identical Coanda evaporation chambers 44. The Coanda evaporation chambers 44 of this embodiment are elliptic cylinders, as opposed to circular cylinders, and are substantially straight along their lengths which extend from a proximal end 43 connected to the inlet manifold 42 to a distal end 45 connected to the outlet manifold 46. The eight Coanda evaporation chambers 44 of this embodiment are connected to a plurality of cooling fins 49 aligned perpendicular to the lengths of Coanda evaporation chambers 44. In this embodiment, the cooling fins 49 are attached to all eight of the Coanda evaporation chambers 44. The inlet manifold 42 may include internal valves, not shown, for regulating flow into the Coanda evaporation chambers 44. When the load on a refrigeration system is low, the inlet manifold 42 may feed refrigerants to only a few or one of the Coanda evaporation chambers 44. If the load increases, the inlet manifold 46 may feed refrigerant to more or all Coanda evaporation chambers 44. The Coanda evaporation chambers 44 may be aligned substantially horizontally, or may be tilted such that their distal ends 45 are higher than their proximal ends 43, or vice versa.

(23) A pulse wave injector 55 receives liquid refrigerant from a typical condenser upstream from the evaporator 40. The pulse wave injector 55 feeds liquid refrigerant to the inlet manifold 42 which then distributes the pulsed liquid refrigerant into the linear refrigerant atomization tubes 48 which are centrally positioned inside each of the Coanda evaporation chambers 44. In this embodiment, each of the linear refrigerant atomization tubes 48 comprises a plurality of sequentially smaller sections having progressively smaller radii and are shown in more detail in FIG. 3. Each of the linear refrigerant atomization tubes 48 has several small holes arranged in a spiral pattern along the entire length of the atomizer 48. The holes may be as small as 100 microns in diameter and may be formed by laser drilling or other techniques. Refrigerant is ejected evenly through the holes of the spray pattern of the atomizer 48, forming droplets, or particles, of liquid refrigerant. The spray pattern of the ejected particles substantially completely coats the inside walls of the evaporator chambers 44 with a thin sheet of liquid refrigerant. This thin sheet of liquid refrigerant evaporates substantially instantaneously into a vapor that then travel from the Coanda evaporation chambers 44 to the outlet manifold 46, and proceed to a compressor as with standard existing refrigeration systems.

(24) The spray patterns of the linear refrigerant atomization tubes 48 substantially maximize heat transfer between the refrigerant and an ambient fluid flowing over the Coanda evaporation chambers 44. The inventors have found that this refrigerant evaporation process is improved by supplying liquid refrigerant to the atomization tubes 48 in a series of pulsed waves provided by the pulse wave injector 55. Supplying liquid refrigerant in a series of rapid pulses allows all of the liquid refrigerant from one pulse to evaporate off the inner wall 56 of the Coanda evaporation chambers 44 prior to receiving a second coating from a subsequent pulse. This prevents pooling or collecting of refrigerant within the evaporator chamber 44. Thus, applying liquid refrigerant particles to the inner wall 56 in pulse waves improves the efficiency of vaporization, generally eliminating the need to superheat the evaporator. In addition, the rapid pulsing impinging of liquid refrigerant against the inner wall 56 removes lubricating oils that otherwise accumulate on the inner wall 56, thus reducing or eliminating the insulating effect caused by accumulated oil on the inner wall 56.

(25) FIG. 3 shows a cutaway view of a single Coanda evaporation chamber 44 of the evaporator 40 shown in FIG. 2. The Coanda evaporation chamber 44 extends from its proximal end 43 to the distal end 45. During use, a fluid such as air or water flows across and impinges the outer wall 50. The linear atomization tube 48 extends from the inlet manifold 42, through the proximal end 43 and extends distally toward the distal end 45 through the center of the Coanda evaporation chamber 44. The linear atomization tube 48 has a multitude of small ejection holes (not shown), as small as 100μ in diameter or smaller. Liquid refrigerant enters the linear atomization tube 48 from the inlet manifold 42 in a series of pulsed waves. The linear atomization tube 48 has a decreasing cross-sectional area as it travels through the Coanda evaporation chamber toward the distal end 43. In the embodiment shown in FIG. 3, the linear atomization tube 48 comprises four sections 54, each progressively smaller. Linear atomization tube 48 is cylindrical and each section 54 has a progressively smaller radius in the distal direction. Those skilled in the art will appreciate that this results in the liquid refrigerant reach each of the ejection holes at substantially the same pressure. This allows the linear atomization tube 48 to coat the inner wall 56 substantially evenly along the entire length of the Coanda evaporation chamber 44. Each Coanda evaporation chamber 48 has openings in its distal end 45 that allows both vaporized refrigerant and lubricating oil to exit the chamber.

(26) FIGS. 4-7 show an alternative embodiment of a Coanda evaporation chamber 60. Coanda evaporation chamber 60 is substantially straight and has a length defined by a proximal end 62 and a distal end 64. Coanda evaporation chamber 60 has a cross-sectional shape of an ellipse that is pointed on each end, i.e. an airfoil shape. Coanda evaporation chamber 60 has an outer surface 68 having a plurality of fins 70 that are perpendicular to its length. Refrigerant ejected from a linear atomization to evenly coats the and are wall 74 before evaporating. FIG. 5 shows the distal end 64. A plurality of vapor outlet holes 76 are located in the distal end 64 near the top of the Coanda evaporation chamber 60, and a plurality of oil outlet holes 78 lie near the bottom of the chamber 60 in the distal end 64. In this embodiment, there are eight vapor outlet holes 76 and three oil outlet holes 78. There is an opening 72 and the proximal end 62 for receiving a linear atomization tube, as shown in FIG. 6.

(27) FIG. 8 shows a linear atomization tube 90 that is cylindrical in shape and includes several rows 92 of ejection holes 94 along the length of the tube 90. In this embodiment, the linear atomization tube 90 has a diameter of 0.125″ and the rows 92 are spaced 0.125″ apart. Each row 92 includes 24 ejection holes 94, each 100 microns wide and spaced 15° apart. Each ejection holes 94 of each successive row 92 has holes that are 7.5° rotated from the orientation of the holes of the previous row. This creates a spiral pattern that helps to ensure an even distribution of ejected refrigerant particles across the inner wall of a Coanda ejection chamber.

(28) FIG. 9 shows an alternative embodiment of a linear atomization tube 100 that is cylindrical in shape and includes several rows 102 of ejection holes 104 along the length of the tube 100. In this embodiments, the linear atomization tube 100 has a diameter of 0.125″ and the rows 102 are spaced 0.125″ apart. Each row 102 includes 12 ejection holes 94, each 100 microns wide and spaced 30° apart. Each ejection holes 104 of each successive row 102 has holes that are 15° rotated from the orientation of the holes of the previous row. This creates a spiral pattern that helps to ensure an even distribution of ejected refrigerant particles across the inner wall of a Coanda ejection chamber.

(29) During use, refrigerant enters the inlet manifold and sprays a pulse wave expansion of high quality refrigerant through a linear atomization tube directly onto the inner wall of a Coanda evaporation chamber in a predetermined pattern. Each linear atomization tube has the nature of a throttle (flow control) by a pulse wave expansion device in conjunction with the linear atomization tube consisting of an array of thousands of 100 micron sized or smaller holes with equal, spiral, spacing. The tubes perform the function of the expansion device, only now there are thousands of pulse wave expansion particles evenly distributed to the inner wall of the evaporator chamber. The thousands of pulse wave expansion devices insure that refrigerant enters each evaporator chamber in the form of droplets of 100 microns or less. This linear pulse wave expansion device with a directional spray array provides a direct refrigerant spray pattern to the entire inner wall surfaces. This pulse wave expansion of refrigerant vaporizes instantly as it contacts the entire area of the inner wall of the evaporator. An additional effect of this pulse wave refrigerant spray distribution system is to scrub and emulsify refrigerant oils off the inner evaporator walls continuously which prevents oil clogging and oil insulating effects typically found in existing evaporator designs. The vapor is now removed and the oil exits at the lowest point of the evaporation chamber.

(30) The linear atomization tube in accordance with the principles of the invention provides a wetted spray of 100-micron or less sized particles of refrigerant perpendicularly and directly onto the inside wall of the evaporator chamber. These micro sized particles tend to keep from combining to form larger globules of solid liquid, which immensely improves the rate of evaporation. This is an advantage with the newer environmentally friendly refrigerants having high boiling points. Evaporators have also increased surface area to compensate for these environmentally friendly Refrigerant replacements.

(31) Optionally, the distal end of the Coanda evaporation chamber can be angled downward as much as thirty degrees, to assist oil droplets to exit the evaporation chamber and return to the compressor. This Coanda evaporation chamber and integrated linear atomization tube also does not require superheating at the outlet of the evaporator, only a minimum superheat at the inlet of the compressor. The superheat at the compressor is maintained by a pressure regulating control valve (mechanical or electronic) mounted on the liquid line at the inlet of the liquid manifold. Another flow control device is an electronic pulsating injector mounted prior to each individual LRAD tube, or a single pulsating injector to all the circuits on the manifold. The control method could also be a combination of both, an electronic pressure regulating and pulse wave device. The vapor of the refrigerant after evaporation leaves the evaporation chamber through a predetermined amount of holes in the upper portion of each oval chamber, or a single outlet (pipe fitting) that can or may be pulled from one or both ends of the evaporator. The oil escapes through holes on the lower portion of the oval chamber.

(32) FIG. 10 shows an alternative embodiment of an evaporator 110 in accordance with the principles of the invention. In this embodiment, a pulse wave control 112 is positioned between the inlet manifold 114 and each individual linear atomization tube 116 for each individual Coanda evaporation to 118. This provides more precise control and can lead to increased overall evaporator efficiency. This type of control also enables an individual Coanda evaporation chamber 118 to defrost without stopping the refrigeration process of the remaining evaporation chambers. This is crucial in medium temperature food storage.

(33) FIG. 11 shows another alternative embodiment of an evaporator 130 in accordance with the principles of the invention. This embodiment includes all the same features as the embodiment shown in FIG. 2. However, in this embodiment, an electronically modulating valve 132 controls flow into the inlet manifold 134. The modulating valve 132 allows an operator to reduce or increase the liquid refrigerant pressure in order to maintain the proper amount of refrigerant flow to match the load of refrigeration system.

(34) FIG. 12 shows another alternative embodiment of an evaporator 140 having a plurality of Coanda evaporation chambers 142. In this embodiment, the evaporator 140 includes all of the features of the embodiment shown in FIG. 11, and is also configured so that the flow of the refrigerant may be reversed, allowing the evaporator 140 optionally form the function of a condenser. The evaporator outlet manifold 144 now becomes the condenser discharge manifold and the discharge vapor will enter the Coanda evaporation chambers 142 through the vapor holes and oil holes in their distal ends 148. As the vapor condenses and converts to a liquid, the liquid refrigerant will exit the Coanda evaporation chambers 142 at their proximal ends 149 through a liquid outlet manifold 150 and then through a check valve 152 and into the liquid line. The control valve 154 will be closed during the heat pump mode to prevent discharge vapor from going backwards through the inlet manifold 156.

(35) FIGS. 13 and 14 show a plate heat exchanger 160 in accordance with the principles of the invention. The plate heat exchanger 160 is affixed to an outlet manifold 164 similar to those described in the other embodiments. The liquid line 162 from the condensor is bonded to the exterior wall of the outlet manifold 164. As the liquid refrigerant flows through the plate heat exchanger circuit 168 it will become sub cooled prior to entering the linear atomization tubes via subcooling outlet 170. The outlet manifold 164 may receive saturated droplets through the vapor holes and enter the interior wall of the header and vaporize as it hits the outside wall of the outlet manifold. The plate heat exchanger 160 will transfer heat from refrigerant in the plate heat exchanger 160 to refrigerant droplets inside the outlet manifold 164, thereby sub cooling the refrigerant before it is fed into the linear atomization tubes.

(36) The present invention also includes a DRAD (Disc Refrigerant Atomization Design) which is a disc with thousands of holes that can be used as a retrofit for existing serpentine type or chamber style evaporators. The thousands of laser drilled holes in the disc provide individual pulse wave expansions that are propelled from the high pressure liquid into the evaporator circuit.

(37) Whereas, the present invention has been described in relation to the drawings attached hereto, other and further modifications, apart from those shown or suggested herein, may be made within the spirit and scope of this invention. Those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. Descriptions of the embodiments shown in the drawings should not be construed as limiting or defining the ordinary and plain meanings of the terms of the claims unless such is explicitly indicated. The claims should be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.