WO2002042692A1

WO2002042692A1 - Air circulation system for a chamber

Info

Publication number: WO2002042692A1
Application number: PCT/US2001/014315
Authority: WO
Original assignee: Qualmark Corporation
Priority date: 2000-06-09
Filing date: 2001-05-17
Publication date: 2002-05-30
Also published as: AU2002214530A1

Abstract

An air straightening system for staightening circulating air and air circulation system (10) mounted within a chamber (12) are provided. The chamber (12) receives a product being tested or processed and has a first chamber wall. The air straightening system comprises an air straightening device having a plurality of cells for straightenening the air flow prior to the air flow reaching the product. The air circulation system comprises an enclosure (30) defined within the chamber (12) with the enclosure (30) receiving air from the chamber and directing a first portion of the air back into the product receiving area of the chamber. An air circulation space is defined between the enclosure and the first wall of the chamber and is separated from the product receiving area by the enclosure. The air circulation space receives a second portion of the air with the second portion of air entering the air circulation space and traveling substantially along the lenght of the enclosure.

Description

AIR CIRCULATION SYSTEM FOR A CHAMBER

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to an air circulation system for a chamber and, more particularly, it relates to an air circulation system for a chamber which is easily installable within the chamber, minimizes heat loss within the chamber by reducing the amount of coolant use, increases the efficiency of the chamber by straightening the air flow within the chamber, and maximizes airflow efficiency through the chamber.

2. Description of the Prior Art Chambers for testing the reliability, durability, and processing of manufactured products are well known in the art. Testing chambers are typically used either under controlled laboratory conditions or in conjunction with an assembly line. The chambers often have circulating air, which gives the added flexibility of testing for defects in the manufactured product which can be exposed by elevated or lowered temperature and/or temperature cycling. The chambers have a circulating air assembly typically mounted at the top of the chamber for drawing air from the interior of the chamber with at least one fan and then directing the air back to the interior of the chamber. In order to lower the temperature of the test chamber, a cooling substance, coolant, or air flowing over cooled coils is typically introduced into the circulated air within circulating air assembly of the chamber in such a manner as to lower the temperature of the circulated air directed toward and about the tested product. In order to increase the temperature of the circulating air within the chamber, circulating air is typically driven through a heating unit mounted within the circulating air assembly and circulated about the tested product within the chamber. Typically, the cooling substance used in the chamber is liquid nitrogen (LN₂) or carbon dioxide (C0 ). The cooling substance is introduced into the circulated air through a coolant injection mechanism at a point near or adjacent the heating unit. Unfortunately, conventional chambers inject the cooling substance directly across the heating unit thereby decreasing efficiency in an attempt to cool the heating unit. Due to the positioning of the cooling injection mechanism within the conventional chamber, most of the cooling substance is used to actually cool the circulating air assembly before the circulating air ever reaches the tested product. In fact, a extremely large amount of liquid nitrogen is required during testing of products thereby creating unnecessary cost and expense of wasted liquid nitrogen and increased testing times. Sometimes these chambers also include shaker tables having a two-piece platform or mounting table having a top piece upon which a product to be tested is mounted and a bottom piece secured to the top piece by bonding or mechanical fasteners. At least one vibrator assembly is typically attached to the bottom piece of the mounting table by a mounting bolt and vibrates the mounting table thereby vibrating the product mounted upon the mounting table. The vibrator assembly generally consists of a housing having a slidable piston mounted therein. The slidable piston strikes a programmer comprising a shock absorbing material to achieve a predicted predetermined shock response. An accelerometer(s) mounted to the bottom piece measures the acceleration level of the mounting table in one or all orthogonal directions, e.g., the -axis direction (in plane), the_y-axis direction (in plane), and the z-axis direction (out of plane).

SUMMARY The present invention additionally includes a cooling system for a chamber. The chamber circulates air about a product being tested or processed. The cooling system comprises an injection mechanism for injecting coolant into the circulating air and a vaporization device for vaporizing the coolant prior to the mixed coolant and circulating air reaching the product being tested. The present invention further includes an air straightening system for straightening circulating air within a chamber. The chamber receives a product being tested or processed. The air straightening system comprises an air straightening device having a plurality of cells for straightening the air flow prior to the air flow reaching the product. The present invention further still includes a method for circulating air within a chamber. The chamber receives a product to be tested. The method comprises providing at least one fan, driving the air through the chamber with the fan, and straightening the airflow between the fan and the product. The present invention additionally includes an air circulation system mounted within a chamber. The chamber has a first chamber wall and a product receiving area. The air circulation system comprises an enclosure defined within the chamber with the enclosure receiving air from the chamber and directing a first portion of the air back into the product receiving area of the chamber. An air circulation space is defined between the enclosure and the first wall of the chamber, separated from the product receiving area by the enclosure, with the air circulation space receiving a second portion of air and the second portion of air entering the air circulation space and traveling substantially along the length of the enclosure. The present invention further still includes a method for circulating air within a chamber with the chamber having a product receiving area. The method comprises defining an enclosure within the chamber, defining an air circulation space between the enclosure and the chamber with the air circulation space separated from the product receiving area by the enclosure, introducing air into the enclosure from the chamber, directing a first portion of the air back into the chamber, and directing a second portion of the air into the air circulation space.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and form a part of the specification, illustrate preferred embodiments of the present invention, and together with the descriptions serve to explain the principles of the invention. FIG. 1 is a perspective view illustrating an air circulation system for a chamber, constructed in accordance with the present invention, with the air circulation system being a one-piece plenum mounted along a top wall of the chamber; FIG. 2 is a perspective view illustrating the air circulation system for a chamber of FIG. 1, constructed in accordance with the present invention, with an air portal for allowing air to exit the chamber. FIG. 3 is a sectional view illustrating the air circulation system for a chamber taken along line A—A, constructed in accordance with the present invention, with the secondary air path to heat and cool the one-piece plenum; FIG. 4 is a top view illustrating the air circulation system for a chamber of FIG. 1, constructed in accordance with the present invention, with the airflow traveling through the diverters and spreading across the width of the air circulation being noted; FIG. 5 is an elevational side view illustrating the air circulation system for a chamber, constructed in accordance with the present invention; FIG. 6 is a bottom view illustrating the air circulation system for a chamber of FIG. 1, constructed in accordance with the present invention; FIG. 7 is a top view illustrating the air circulation system for a chamber of FIG. 1, constructed in accordance with the present invention, indicating the direction of air flow within the chamber; FIG. 8 is an elevational side view illustrating an inlet cone for the air circulation system, constructed in accordance with the present invention; FIG. 9 is a top view illustrating the inlet cone for the air circulation system of FIG. 8, constructed in accordance with the present invention; FIG. 10 is an elevational side view illustrating a counter-rotating fan for the air circulation system for a chamber, constructed in accordance with the present invention; FIG. 11 is a perspective view illustrating the air circulation system for a chamber, constructed in accordance with the present invention, with a heating unit having a plurality of heating frames for elevating the temperature of the air circulating through the air circulation system; FIG. 12 is a bottom view illustrating the air circulation system for a chamber of FIG. 11, constructed in accordance with the present invention, with the heating unit; FIG. 13 is a front elevational view of a heater frame of the heating unit, constructed in accordance with the present invention; FIG. 14 is a side elevational view of a heating component bracket for securing together a plurality of heating frames, constructed in accordance with the present invention; FIG. 15 is an end view of a plurality of heating frames secured together by a heating component bracket, constructed in accordance with the present invention; FIG. 16 is a elevational side view illustrating a vaporization mechanism for use with the air circulation system, constructed in accordance with the present invention, having a substantially grid-like, honeycomb configuration; FIG. 17 is an end view illustrating the vaporization mechanism of FIG. 16, constructed in accordance with the present invention; and FIG. 18 is a elevational side view illustrating a honeycomb of the vaporization mechanism of FIG. 16, constructed in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As illustrated in FIG. 1, the present invention is an air circulation system, indicated generally at 10, for circulating air within a chamber 12. The chamber 12 tests the reliability, durability, and/or processing of manufactured products (not shown) mounted within the chamber 12. It should be noted that the chamber 12 can be a thermal chamber having a heating unit for heating the circulating air and/or a cooling unit for cooling the circulating air within the chamber and/or a refrigeration chamber having only a refrigeration unit for cooling the circulating air within the chamber 12. The heating unit and cooling systems will be described in further detail below. As illustrated in FIG. 1, the chamber 12 includes a top wall 14, a bottom wall 16 substantially opposite the top wall 14, a plurality of side walls 18 between the top wall 14 and the bottom wall 16, and an access door 20 defining an enclosed chamber 22. Still referring to FIG. 2, the chamber 12 can additionally include, although not required, a shaker table assembly 24 mounted on a foundation (not shown) within the enclosed chamber 22 and is operated such that the shaker table assembly 24 and the attached testable or manufactured product is vibrated. The foundation is an essentially vibration-free support for the shaker table assembly 24. Although typically supported from below, the shaker table assembly 24 can also be supported from any direction. While the air circulation system 10 of the present invention is a novel improvement for inclusion in a chamber, operation and construction of the shaker table 24 and the chamber 12 is further described in U.S. Patent No. 5, 589,637, assigned to the same assignee of the present application, and is hereby herein incorporated by reference. The chamber 12 further includes an insulation blanket 26 secured to the side walls 18 and the access door 20 of the chamber 12. The insulation blankets 26 further insulate the chamber 12 to inhibit temperature loss through the side walls 18 and the access door 20 and maintain the desired, predetermined temperature of the circulating air through the chamber 12 and about the product being tested. As illustrated in FIGS. 1-6, the air circulation system 10 is mounted to the top wall 14 of the chamber 12. The air circulation system 10 circulates air, either heated, cooled, or ambient, about the product being tested within the chamber 12. The heated and cooled circulating air increases the stress on the product being tested to assist in determining durability and life of the product. The actual heating and cooling of the circulating air will be described in further detail below. The air circulation system 10 defines an enclosure 30 for receiving components of the air circulation system 10. The enclosure 30 is preferably constructed to be installed to the top wall 14 within the chamber 12 in a single unit, i.e., a one-piece plenum, thereby improving air flow through the enclosure 30 of the air circulation system 10 and the enclosed chamber 22 of the chamber 12. A plurality of fastening mechanisms (not shown), e.g., screws, rivets, etc. maintain the enclosure 30 within the chamber 12. In a preferred embodiment, the enclosure 30 is pop riveted to the side walls 18 of the chamber 12. A gasket (not shown) between the walls of the chamber 12 and between the enclosure 30 and the side walls 18 of the chamber 12 to further insulate the chamber 12 from heating and cooling losses. The enclosure 30 is preferably constructed from a light gauge, stainless steel material and is formed and welded into the single unit for ease in installation. It should be noted that while the enclosure 30 of the air circulation system 10 has been described as being constructed from a light gauge, stainless steel material, it is within the scope of the present invention to construct the enclosure 30 from other materials including, but not limited to, other metals, plastic, ceramics, etc. Furthermore, the enclosure 30 can be defined by a plate (not shown) extending across the width of the chamber 12. The air circulation system 10 further includes at least two counter rotating fans 32, a first fan 32a and a second fan 32b, for drawing air into the enclosure 30 of the air circulation system 30 from within the enclosed chamber 22 of the chamber 12 and driving the air through the enclosure 30 to exit the enclosure 30 from a plurality of outlet ports 34 for directing the air back toward the shaker table assembly 24 and the product being tested. In accordance with the present invention, the first fan 32a rotates in a direction substantially opposite the rotation of the second fan 32b. Each fan 32 preferably has a two (2 hp) horsepower motor and a blower wheel diameter of approximately fourteen (14") inches to fifteen (15") inches, although other size fans and motors are within the scope of the present invention. The inventors of the present application have found that by using the counter rotating fans 32, as described therein, there is less air diversion in an area 36, as illustrated in FIG. 4, behind the counter rotating fans 32 and, unlike conventional chambers, thereby increasing the volume of air flow through the enclosure 30. In fact, the counter rotating fans 32 increase the air flow volume through the enclosure 30 of the air circulation system 10 with an efficiency between approximately seventy (70%) percent and approximately ninety (90%) percent as compared to conventional chambers which typically have an efficiency of approximately fifty (50%) percent. As illustrated in FIGS. 8 and 9, each counter rotating fan 32 of the air circulation system 10 of the present invention has an inlet cone 28 mounted to the enclosure 30 and extending into the enclosed chamber 22. Each inlet cone 28 provides a non-disruptive curved entrance for the circulating air entering the fan 28 thereby eliminating the sharp angles present in conventional fans and inlets and allowing a smooth transition and less disruption of the airflow entering the fans 32 from the enclosed chamber 22. By providing the inlet cones 28 with an entrance curved in all directions of the airflow, the air is diverted directly into the counter rotating fans 32 thereby minimizing the height of the enclosure 30 of the air circulation system 10 and increasing the height of the enclosed chamber 22. The inlet cone 28 has an opening 110 for receiving air from the enclosed chamber 22. The opening 110 preferably has a diameter of approximately ten (10") inches although an opening 110 having a diameter other than approximately ten (10") inches is within the scope of the present invention. As the counter rotating fans 32 draw the air from within the enclosed chamber 22 of the chamber 12 and directs the air through the enclosure 30 of the air circulation system 10, a plurality of air di verier plates 38 are provided to increase the efficiency of the air flow through the enclosure 30 and to evenly distribute the air across a heating unit 42. The heating unit 42 will be described in further detail below. Preferably, the air diverter plates 38 are constructed into two separate diverter plate units 40 and positioned within the enclosure 30 prior to mounting the enclosure 30 to the top wall 14 of the chamber 12. This allows the air diverter plates 38 to be inserted into the enclosure 30 in an easy and inexpensive manner. Furthermore, since the air diverter plates 38 span the entire height of the enclosure 30, the air diverter plates 38 provide additional center support for the enclosure 30 thereby inhibiting the enclosure 30 from deforming in the z- direction. As illustrated in FIGS. 11 and 12, the air circulation system 10 of the present invention further includes the heating unit 42, as mentioned briefly above, mounted within the enclosure 30 of the air circulation system 10 for increasing the temperature of the air to a desired, predetermined temperature as the air circulates through the enclosure 30. As illustrated in FIG. 13, preferably, the heating unit 42 is a modular heating system having individual heating frames 44. As illustrated in FIG. 14, each heating frame 44 has a protruding portion 46. The heating frames 44 are mounted in heating sets of three (3) individual heating frames 44 by a bracket 48 extending over the protruding portion 46 of each heating frame 44. As illustrated in FIG. 15, a bank of three (3) heating sets can be installed within the enclosure 30. To install the heating unit 42 in the air circulation system 10 within the enclosure 30, the enclosure 30 includes a protrusion receiving slot 50 formed therein. As illustrated in FIG. 11, the protruding portions 46 at one end of the heating frames 44 are inserted into the protrusion receiving slot 50. A heating frame aperture 52 at the opposite end of the heating frames 44 is then aligned with a corresponding enclosure aperture 54. A fastening mechanism 56, such as a screw or bolt, is inserted and secured within the heating frame aperture 52 and the enclosing aperture 54. By providing a heating unit 42 as described and illustrated herein, installation of the heating unit 42 within the enclosure 30 can be accomplished in an easy and efficient manner. In thermal chambers, the air circulation system 10 of the present invention further includes a cooling device 58 positioned within the chamber 12 for cooling the temperature of the air to a predetermined temperature as the air circulates through the enclosure 30 of the air circulating system 12. The cooling device 58 includes a distribution manifold 60 positioned within the side wall 18 of the chamber 12 and connected to a coolant supply (not shown) via an inlet pipe 62 or the like. Preferably, the coolant used for cooling the circulating air is liquid nitrogen (LN₂) or liquid carbon dioxide (C0₂) although other coolants are within the scope of the present invention. As noted before, the cooling of the circulating air can be accomplished by providing cooled coils for the circulating air to pass over or through, i.e., a refrigeration unit. A coolant, such as liquid nitrogen, can be forced through the coils to cool the coils and the circulating air passing thereover. As mentioned above, the distribution manifold 60 is positioned within the side wall 18 of the chamber 12. The cooling device 58, including the distribution manifold 60, are insertable into and removable from within the chamber 12 as a one-piece unit for ease of installation, removal, and servicing. The cooling device 58 injects the coolant from the distribution manifold 60 into the circulating air within the enclosure 30 of the air circulation system 10 through a plurality of injection ports 64 extending through the side wall 18 of the chamber 12. The injection ports 64 can be a variety of sizes. For instance, with the distribution manifold 60, as illustrated in FIGS. 5-7, the distribution manifold 60 has a substantially T- shaped configuration. With such a configuration, the distribution manifold 60 preferably includes smaller diameter injection ports 64 nearingly adjacent the inlet pipe 62 and increasingly larger diameter injection ports 64 distant from the inlet pipe 62. Since the amount of coolant flow is dependent upon the pressure within distribution manifold 60, the varying sized injection ports 64 maintain equal distribution of the coolant into the air circulation system 10. An insulation material 66 can be disposed about the distribution manifold 60 and the inlet pipe 62 to maintain the desired, predetermined temperature of the coolant therein. Preferably, the insulation material 66 is a plurality of cork granules although other types of insulation material 66 is within the scope of the present invention. Preferably, the coolant is injected through the plurality of injection ports 64 into the circulating air at a point between the heating unit 42 and the outlet ports 34. For optimum cooling efficiency and minimal heat loss, the injection ports 64 are positioned nearingly adjacent the outlet ports 34 thereby allowing the cooled circulating air to circulate through the enclosed chamber 22 of the chamber 12, and thus the product being tested before the circulating air is circulated out of the enclosed chamber 22 into the enclosure 30 through the fans. By positioning the injection ports 48 closely adjacent the outlet ports 48, the coolant is initially being used to reduce the temperature of the product being tested and not for cooling the heating unit 42 and the enclosure 30 of the air circulation system 10. Therefore, the cooling device 58 of the present invention effectively reduces the amount of coolant use and increases the efficiency of the chamber 12. As the coolant is injected into the circulating air through the injection ports 64, the coolant contacts and passes through a circulation unit 68 mounted immediately adjacent the injection ports 64 for substantially vaporizing the coolant prior to the coolant reaching the product being tested within the chamber 12 and for straightening the air flow as the air leaves the enclosure 30. Vaporization of the coolant is accomplished due to the fact that the temperature of the circulation unit 68 is greater than the boiling point of the coolant. As the cold coolant contacts the circulation unit 68, the coolant is vaporized and effectively mixed with the circulating air. It should be noted that in refrigeration and other similar chambers, the circulation unit 68 only straightens the air since vaporization is not necessary. The circulation unit 68 of the air circulation system 10 of the present invention is preferably positioned between approximately fifteen (15") inches and twenty (20") inches from the injection ports 64 for optimum coolant vaporization. It should be noted, however, that positioning the circulation unit 68 at a distance less than approximately fifteen (15") inches from the injection ports 64 and at a distance greater than approximately twenty (20") inches from the injection ports 64 is within the scope of the present invention so long as the liquid nitrogen is sufficiently vaporized prior to circulating about the product being tested. As illustrated in FIGS. 16 - 18, the circulation unit 68 preferably has a substantially grid-like cross-sectional configuration which substantially vaporizes the liquid nitrogen and straightens the airflow by breaking up any eddys in the airflow prior to the circulating air exiting the air circulating system 12 through the outlet ports 34. The circulation unit 68 has a plurality of cells 69. Preferably, each cell 69 has a substantially honeycomb cross-sectional configuration having six (6) sides. While the cells 69 have been described as having a substantially honeycomb cross-sectional configuration with six (6) sides, it is within the scope of the present invention for the cells 69 to have other cross-sectional configurations with various number of sides including, but not limited to round, oval, elliptical, triangular, quadrilateral, etc. The inventors of the present application have discovered that the smaller the cell size, the coolant experiences improved vaporization due to increased surface area. Furthermore, the smaller cell sizes promotes air flow circulation throughout the chamber 12. In the embodiment of the circulation unit 68 having cells 69 with a honeycomb cross- sectional configuration, the width of two opposite sides are each approximately 0.16 inch and the width of the remaining four side walls are each approximately 0.08 inch with the remaining four side walls being angled from the two opposite side walls at an angle of approximately sixty (60°) degrees . Each side wall of the honeycomb cell 69 preferably has a thickness of approximately 0.0003 inch. It should be noted that it is within the scope of the present invention, however, for the circulation unit 68 to have varying cross-sectional configurations and/or dimensions so long as the circulating air travels toward the outlet ports 34, the circulation unit 68 straightens the airflow of the circulating air and promotes vaporization of the liquid nitrogen or other coolant. The circulation unit 68 preferably has a length of approximately forty-eight (48") inches, a height of approximately four and three-fourths (4.75") inches, and a thickness of approximately one (1") inch although other lengths, heights, and thicknesses are within the scope of the present invention. The inventors of the present invention have discovered that the circulating air which is normally exhausted from the chamber can be used to cool the enclosure 30 of the air circulation system 10. Therefore, as illustrated in FIGS. 2 and 3, the air circulation system 10 includes a secondary exhaust system 70 for cooling the enclosure 30. The secondary exhaust system 70 includes a space 72 between the enclosure 30 and the top wall 14 of the chamber 12. An exit portal 74 formed in the enclosure 30 distant from the fans 32 allows circulating air to exit the enclosure 30 and enter the space 72. As the circulating air enters the space 72 between the enclosure 30 and the top wall 14 of the chamber 12, the circulating air travels within the space 72 between the enclosure 30 and the top wall 14 of the chamber 12 until the circulating air exits the space 72 through an air exit opening 76 formed in the top wall 14 of the chamber 12 substantially above the fans 32. The secondary exhaust system 70 of the air circulation system 10 of the present invention allows cooled air which would normally exit the enclosure 30 adjacent the fans 32 to assist in cooling the enclosure 30 prior to exiting the chamber 12. In particular, as the cooled air enters the enclosure 30 from the chamber 12, the fans drives the cooled air through the heating unit 42 before a portion of the cooled air exits the enclosure 30 through the exit portal 74 into the space 72. The cooled air then travels within the space 72 in a generally opposite direction along substantially the entire length of the enclosure 30 until the cooled air exits the space 72 through the exit opening 76. The secondary exhaust system 70 cools the enclosure 30, especially in the area about the heating unit 42, maintains the desired temperature of the air circulating in the chamber 12, and reduces the amount of cooling fluid necessary during operation of the chamber 12. While the present invention has been described as having the exit portal 74 positioned distant from the fans 32 and subsequent to the heating unit 42, it is within the scope of the present invention to have the exit portal 74 positioned at any position along the enclosure including, but not limited to, adjacent the fans 32. Since the circulating air will only enter into the secondary exhaust system 70 when under pressure, such as upon injection of the coolant, the secondary exhaust system 70 is primarily used for cooling the enclosure 30. It should be noted, however, that since some expansion occurs during heating operations, the circulating air can also enter the secondary exhaust system 70 during heating of the circulating air. It is often desirable to have a light source within the enclosed chamber 22 of the chamber 12 to aid and assist the operator in testing the product. Therefore, an additional added feature for minimizing heat loss and controlling the temperature within the enclosed chamber 22 of the chamber 12 is provided. As illustrated in FIG. 2, at least one non-heat generating lighting source 78 can be mounted within the enclosed chamber 22. Preferably, the non-heat generating lighting source 78 are fiber-optic lights, but other types of non-heat generating light sources are within the scope of the present invention. The fiber-optic lights minimize the heat generated when lighting the enclosed chamber 22. The air circulation system 10 of the present invention effectively minimizes heat loss prior to the coolant reaching the product 13 thereby reducing the amount of coolant use and increasing the efficiency of the chamber 12 by straightening the circulating air therein. Furthermore, the air circulation system 10 of the present invention injects a coolant, such as liquid nitrogen, into the circulating air of the chamber 12 at a point distant from the heating ^■ unit 42 and near the product 13 being tested. Additionally, the air circulation system 10 which substantially vaporizes the coolant prior to the coolant reaching the product being tested thereby increasing efficient use of the coolant during testing procedures. The air circulation system 10 of the present invention effectively increases the efficiency of the air flow through the chamber 12 and allows the easy installation, maintenance, and removal of components therein. Specially designed inlet cones allow air to enter the enclosure 30 in a substantially unimpeded manner and allows the height of the enclosure 30 to be minimized. Counter rotating fans 32a, 32b increase the volume of air flowing through the enclosure 30 and, thus within the chamber 12. Air diverter plates 38 are mounted adjacent the fans 32 to evenly distribute the air flow across the width of the enclosure 30 and through the heating unit 42, if present. A modular heating unit 42 can be constructed and installed within the enclosure 30 thereby allowing easy installation, maintenance, and replacement. A secondary exhaust system 70 is provided to gain full use of heated or cooled air to assist in heating or cooling the enclosure 30 thereby decreasing the amount of heating and/or cooling required. The foregoing exemplary descriptions and the illustrative preferred embodiments of the present invention have been explained in the drawings and described in detail, with varying modifications and alternative embodiments being taught. While the invention has been so shown, described and illustrated, it should be understood by those skilled in the art that equivalent changes in form and detail may be made therein without departing from the true spirit and scope of the invention, and that the scope of the present invention is to be limited only to the claims except as precluded by the prior art. Moreover, the invention as disclosed herein, may be suitably practiced in the absence of the specific elements which are disclosed herein.

Claims

CLAIMSWhat is claimed is:

1. A cooling system for a chamber, the chamber circulating air about a product being tested, the cooling system comprising: an injection mechanism for injecting coolant into the circulating air; and a vaporization device for vaporizing the coolant prior to the mixed coolant and circulating air reaching the product being tested.

2. The cooling system of claim 1 wherein the injection mechanism is positioned nearingly adjacent the vaporization device.

3. The cooling system of claim 1 wherein the injection mechanism includes a distribution manifold and at least one injection port.

4. The cooling system of claim 1 wherein the coolant selected from the group consisting of liquid nitrogen (LN ) and liquid carbon dioxide (C0₂) .

5. The cooling system of claim 1 wherein the vaporization device straightens the air flow.

6. The cooling system of claim 1 wherein the vaporization device has a plurality of cells, each cell having a cross-sectional configuration selected from the group consisting of round, oval, elliptical, triangular, quadrilateral, and honeycomb.

7. An air straightening system for straightening circulating air within a chamber, the chamber receiving a product being tested or processed, the air straightening system comprising: an air straightening device having a plurality of cells for straightening the air flow prior to the air flow reaching the product.

8. The air straightening system of claim 7 wherein each cell has a cross-sectional configuration selected from the group consisting of round, oval, elliptical, triangular, quadrilateral, and honeycomb.

9. The air straightening system of claim 7 and further comprising: an injection mechanism for injecting coolant into the circulating air.

10. The air straightening system of claim 9 wherein the air straightening device vaporizes the coolant prior to the mixed coolant and circulating air reaching the product being tested.

11. The air straightening system of claim 9 wherein the injection mechanism is positioned nearingly adjacent the air straightening device.

12. The air straightening system of claim 9 wherein the injection mechanism includes a distribution manifold and at least one injection port.

13. The air straightening system of claim 9 wherein the coolant selected from the group consisting of liquid nitrogen (LN₂) and liquid carbon dioxide (C0 ) .

14. An air circulation system mounted within a chamber, the chamber having a first chamber wall, the chamber having a product receiving area, the air circulation system comprising: an enclosure defined within the chamber, the enclosure receiving air from the chamber and directing a first portion of the air back into the product receiving area of the chamber; and an air circulation space defined between the enclosure and the first wall of the chamber, separated from the product receiving area by the enclosure, the air circulation space receiving a second portion of the air, the second portion of air entering the air circulation space and traveling substantially along the length of the enclosure.

15. The air circulation system of claim 14 wherein the chamber has a top chamber wall and the enclosure has a top enclosure wall and a bottom enclosure wall, the top enclosure wall being mounted adjacent the top chamber wall thereby defining the air circulation space therebetween.

16. The air circulation system of claim 15 and further comprising: an air introduction opening formed in the enclosure for introducing circulating air into the air circulation space.

17. The air circulation system of claim 14 and further comprising: an air exit opening formed in the first wall of the chamber allowing the circulating air within the air circulation space to exit from the chamber.

18. The air circulation system of claim 14 and further comprising: at least one fan mounted within the enclosure adjacent the inlet for directing the air into the air circulation space and through the enclosure; and an inlet cone mounted in the inlet adjacent each fan, the inlet cone having a smoothly rounded configuration for airflow into the enclosure.

19. The air circulation system of claim 18 wherein at least a portion of the inlet cone extends into the chamber, the portion extending into the chamber being curved about and into each inlet.

20. The air circulation system of claim 14 and further comprising: a first fan rotating in a first rotation direction; and a second fan rotating in a second rotation direction; wherein the first rotation direction of the first fan is substantially opposite the second rotation direction of the second fan.

21. The air circulation system of claim 14 and further comprising cooling means for cooling the circulating air and heating means for heating the circulating air.

22. The air circulation system of claim 14 and further comprising: insulation means mounted to the walls of the chamber for thermally isolating the chamber.

23. The air circulation system of claim 14 wherein the enclosure is defined by a plate extending across the width of the chamber.

24. A method for circulating air within a chamber, the chamber having a product receiving area, the method comprising: defining an enclosure within the chamber; defining an air circulation space between the enclosure and the chamber, the air circulation space separated from the product receiving area by the enclosure; introducing air into the enclosure from the chamber; directing a first portion of the air back into the chamber; and directing a second portion of the air into the air circulation space.

25. The method of claim 24 and further comprising: directing the second portion of the air substantially along the length of the enclosure.

26. The method of claim 24 and further comprising: forming an air introduction opening in the enclosure for introducing the second portion of the air into the air circulation space.

27. The method of claim 24 and further comprising: forming an air exit opening in the chamber allowing the second portion of the air within the air circulation space to exit from the chamber.

28. The method of claim 24 and further comprising: mounting at least one fan within the enclosure adjacent the inlet for directing the air into the air circulation space and through the enclosure; and mounting an inlet cone in the inlet adjacent each fan, the inlet cone having a smoothly rounded configuration for airflow into the enclosure.

29. The method of claim 28 and further comprising: extending at least a portion of the inlet cone into the chamber, the portion extending into the chamber being curved about and into each inlet.