Abstract:
A temperature adjustable airflow device includes a vortex tube having a high pressure gas inlet and cooled and heated outlets. A mixing chamber is provided having first and second ends, one gas inlet end at the first end and a gas outlet end at the second end, and an intermediate gas inlet end between the first and second ends. A high pressure inlet conduit is connected to the high pressure gas inlet of the vortex tube and to the gas inlet of the mixing chamber. The cooled or the heated vortex tube outlet is connected to the intermediate gas inlet end, the mixing chamber mixing high pressure gas with cooled or heated gas, respectively, from the vortex tube to enhance the pressure of the cooled or heated gas emanating from the vortex tube. The arrangement allows cooled or heated gas from the vortex tube to be output for a given application at a higher pressure that would normally be available.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention generally relates to vortex tubes and, more specifically, to a modified temperature adjustable airflow device. 
         [0003]    2. Description of the Prior Art 
         [0004]    Vortex tubes, known since the 1930s, are mechanical devices that convert gas tinder pressure into hot and cold gas streams. It has no moving parts. 
         [0005]    Generally, a typical vortex tube has two openings, one at each end and an intermediate inlet tube for introducing gas under a high pressure into a spiral flow path. While there are different explanations for the way in which vortex tubes work, it is known that when a gas is introduced under high pressure, it is separated into two different streams, a first gas stream exiting one end of the tube being heated air while the gas stream exiting the other end is cooled air. The gases that exit at two opposing ends of the tube being heated and cooled gas streams, are at lower pressures that the pressure of the inlet gas. While vortex tubes are not an efficient as traditional air-conditioning equipment, they are commonly used for inexpensive sport cooling, when compressed air is available. Commercial models, for example, are designed for industrial applications to produce temperature drops of approximately 45° C. (80° F.) from the temperature of the high pressure gas. 
         [0006]    In some instances, it may be preferable to modify the output of the cold air stream exiting, at one end of the vortex tube, by either increasing its pressure or increasing its temperature somewhat. This has been done in the past by adjusting a stopcock within the heated end of the tube that regulates the extent of flow through the heated end. However, because the air exiting this tube can be hot, this is a disadvantage and make cause injury to a user. Also, while such and adjustment at the hot end of the tube may raise the temperature of the gas at the cooled end of the tube, it is not always practical to use this approach to increase the pressure of the cold air exiting the tube. 
         [0007]    As indicated, while has been conventional in the prior art to control the temperature of the discharged cold stream by providing a valve at the hot discharge end of the vortex tube, not only is such placement of a valve at the hot end of the tube inconvenient and potentially dangerous to the user who may be exposed to elevated temperatures, but the closing of the valve necessarily increases the volume of the cold discharge stream. As disclosed in U.S. Pat. No. 3,192,728 such an approach will function to a limited extent. However, this approach will tend to decrease the efficiency of the unit as the valve decreases the volume of the stream to counteract the decrease in the temperature of the stream. 
         [0008]    In U.S. Pat. No. 4,240,261 a temperature-adjustable vortex tube assembly is disclosed. However, this assembly includes a complicated mechanism for mixing the hot and cold discharge streams in an attempt to obtain a desired temperature while maintaining the flow volume of the mixture constant. The device is expensive to fabricate and the efficiency of the unit is reduced because of the manner in which the discharged streams flow in parallel to a common end of the device necessarily resulting in temperature interchanges between the hot and cold streams along such parallel flow paths. 
         [0009]    U.S. Pat. No. 3,208,229 discloses a vortex tube, wherein it is proposed that the inner surface of the tube be roughened to produce turbulence and mixing of the gases that reduce the efficiency of the tube. Furthermore, a control ring is used in conjunction with the blades at the far end of the heated tube to enable the tube to be shortened without loss of efficiency. 
         [0010]    In U.S. Pat. No. 4,339,926 a vortex tube is disclosed that seeks to overcome the disadvantages of prior art vortex tubes. The patent seeks to provide a more simple and inexpensive vortex tube that has a relatively short length relative to the diameter of the tube while still maintaining the optimum temperature differentials at the end of the tubes but without the use of blades or control rings as described in prior references. 
         [0011]    In U.S. Pat. No. 2,819,590 a ventilated suit refrigeration unit is disclosed in which the heated and cooled streams of gas emanating from the vortex tube are mixed by two air flow regulated valves  44 ,  45  interconnected through a rod  51  that may be regulated by a thermostat  58 . 
         [0012]    In U.S. Pat. No. 6,289,679 a non-freeze enhancement for a vortex tube is disclosed in which the hot air flow is permitted to heat the vortex tubes inlet at a cross-section and diaphragm and warm the vortex cold fraction in its discharge pass that result in increasing the unit&#39;s performance reliability. As will be noted, for example, from  FIG. 1  a line  34  connects the heated end  20  of the vortex tube to the heat exchanger at the cooled side. However, the inlet air flow on the pressure, at  40  is not diverted to either side of the vortex tube. 
       SUMMARY OF THE INVENTION 
       [0013]    In order to overcome the above disadvantages inherent in prior art devices, it is an object of the invention to provide a temperature adjustable airflow device that overcomes the inherent disadvantages of such prior know devices. 
         [0014]    It is another object of the invention to provide a temperature adjustable airflow device that is simple construction and economical to the manufactures. 
         [0015]    It is still another object of the invention to provide a temperature adjustable airflow device that utilizes a vortex tube and is easy and safe to use to adjust the temperature of the gas output of the device. 
         [0016]    It is still another object of the invention to provide a temperature adjustable airflow device as in a previous object that provides accurate control of the temperature of the outlet gas of the vortex tube. 
         [0017]    It is still another object of the invention to provide a temperature adjustable airflow device as in a previous object that allows the adjustment of the temperature of the output gas without unduly reducing the efficiency of the device. 
         [0018]    It is still another object of the invention to provide a temperature adjustable airflow device of the type of the discussion that includes a temperature feedback loop for pre-cooling high pressure gas prior to entry into a vortex tube. 
         [0019]    It is yet another object of the invention to provide temperature adjustable airflow device as in the previous object that provides a temperature adjustable airflow device that provides an air stream colder than the stream of cold gas typically available at the output of a vortex tube, and at a higher pressure, by providing a pre-cooling chamber that is cooled by the colder gas exiting the vortex tube that pre-cools the gas in the high pressure input line prior to entry into the high pressure inlet of the vortex tube. 
         [0020]    In order to achieve the above objects the present invention utilizes a relative conventional vortex tube that has two opposing ends one of which releases cooled gas while the other produces heated gas relative to an ambient temperature of a high pressure gas that input into the vortex device. The one of the two vortex tubes that releases the cooled gas is tapped into a mixing chamber that has a gas mixing compartment. A bypass tube connects the high pressure tube that feeds the vortex tube to the mixing compartment of the mixing chamber, an adjustable valve being placed within the bypass tube to allow gas flowing within the bypass tube to be freely transmitted or partially blocked or fully blocked. The high pressure gas that is fed by the bypass tube and the cooled gas that is output of the vortex tube are mixed within the mixing chamber and fed to the outlet of the mixing chamber. The mixed gas will achieve a temperature that is between the ambient temperature of the high pressure gas and the temperature of the cooled gas exiting the vortex tube. This matter, the temperature at the outlet of the mixing chamber can be adjusted while maintaining a relatively high pressure or flow speed of the temperature modified gas. 
         [0021]    In accordance with one presently preferred embodiment, a temperature feedback loop is provided for pre-cooling the high pressure gas being fed into the vortex tube so that the temperature of the cooled air is lower than the temperature that would normally be obtainable by using a conventional vortex tube. This is achieved, for example, by means of a pre-cooling chamber that is cooled by the cold air exiting the vortex tube for cooling the high pressure input gas into a vortex tube. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    With the above additional objects and advantages in view, as will hereinafter appear, this invention comprises the devices, combinations and arrangements of parts hereinafter described by way of example, and illustrated in the accompanying drawings of presently preferred embodiments, in which: 
           [0023]      FIG. 1  is a schematic representation of a temperature adjustable airflow device in accordance with the present invention, shown partially exploded to indicate the manner in which the device is assembled; and 
           [0024]      FIG. 2  is a schematic representation of a temperature adjustable airflow device that includes a pre-cooling chamber as part of a temperature feedback loop for using the cold air from the vortex tube to pre-cool the high pressure gas entering into the vortex tube. 
           [0025]      FIG. 3  is a heat flow diagram representing the heat transfers in the embodiment illustrated in  FIG. 2 ; and 
           [0026]      FIG. 4  is a time temperature chart illustrating the incremental drop in temperature outlet for the embodiment illustrated in  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0027]    Referring specifically to the single Figure, a temperature adjustable airflow device in accordance with the invention is generally designated by the reference numeral  10 . 
         [0028]    The device  10  includes a vortex tube  12  having a cold end outlet  12   a,  a hot end outlet  12   b,  and a spiral chamber  12   c.  The internal construction of the vortex tube is conventional and the details need not to be described. All of the patents that mentioned in the background of the invention are incorporated herein for the teachings of the details of the vortex tubes, and any such construction can be used. The specific construction or details of the vortex tube are not critical and the subject invention may be used with any conventional or modified vortex tube of the type well known to those skilled in the art. 
         [0029]    The vortex tube  12  has at each of the ends  12   a  and  12   b  internal threads  14 . A cold air pipe  16  is provided with an external tread  16   a  at one end and an external tread  16   b  at the other end, the external treads being dimensioned and configured to threadably mesh with the internal treads  14  of the vortex tube, effectively enlarging or extending the ends of the vortex tube. Whether the vortex tube has an adequate length along direction A V  the extension tube  16  may not be required. The same is true of the hot pipe  18  that likewise has external treads  18   a  shown at the end that meshes with the vortex tube. 
         [0030]    As with the conventional vortex tubes, a high pressure inlet pipe  20  is in fluid-flow communication with the interior of the vortex tube and the chamber  12   c.  The details of the chamber  12   c  are not shown as these are well known to those skilled in the art. The high pressure inlet pipe  20  has an outlet  20   a  that is joined to the vortex tube  12 , or may be integrally formed therewith. The high pressure inlet pipe  20  also has an inlet  20   b  that can be connected to a source of high pressure gas in any conventional manner. 
         [0031]    One feature of the invention is the provision of a mixing chamber  22  that has a high pressure inlet opening  22   a,  a cold inlet gas opening  22   b  and an outlet opening  22   c.  A bypass tube  24  has a first tube section  24   a  in fluid flow communication with the high pressure inlet pipe  20  and a tube portion  24   b  fluid flow communication with the mixing chamber  22 . An additional tube portion  24   c  may be provided that aligns the outlet end of the bypass tube with an axis A C  of the mixing chamber  22  although, clearly, the two portions  24   b  and  24   c  are shown as an integral bent tube portion. Another feature of the invention is the provision of a adjustable valve  26  between the two portions  24   a  and  24   b  that can be adjusted from the fully open position, in which case the gas in the tube portion  24   a  may flow freely into the tube portion  24   b,  or may be partially or fully closed to block, wholly or partially, the flow of gas between the portions  24   a  and  24   b.  A pressure gauge  28  is advantageously provided that is connected to the adjustable valve  26  or to one of the two portions  24   a,    24   b  by means of a tube  30  to provide an indication of the level of pressure in the bypass tube  24 . 
         [0032]    While the tube  24  is shown as a bypass tube connected to the same supply of high pressure gas supplying the inlet pipe  20 , it is also possible, and contemplated by the invention, that two separate entries of high pressure are provided, each separately supplying high pressure to the inlet pipe  20  and to the tube  24 , which would no longer be a bypass tube as shown in  FIGS. 1 and 2 . 
         [0033]    Within the interior of the mixing chamber  22  there is provided a mixing compartment, shown as being generally elongated along the chamber axis A C . 
         [0034]    The cold pipe  16 , and specifically its external tread and the remote end  16   b  are dimensioned to mesh with internal threads at the cold gas inlet opening  22   b.  All of the threaded connections are preferably sealed in any conventional manner to prevent the escape of gas through these joints. In this connection, it is also possible to attach the various tubes and pipes shown and discussed above by means other than treated connections. Thus, these tubes may be attached to each other by the conventional means such as welding, adhesive, etc. 
         [0035]    The gas that feeds the mixing chamber  22  by means of the bypass tube  24  is designated by the reference numeral  34 , this being high pressure gas that is at ambient temperature. The cold pipe  16  injects a cold stream of gas  36  into the mixing compartment  32 , at a point intermediate the outlet end of the tube portion  22   c  and the outlet tube  38  of the mixing chamber  22 . 
         [0036]    The specific configuration of the mixing chamber  22  is not critical, although it is preferable that the end of the cold pipe  16  at  16   b  be positioned or is located closer to the outlet opening  22   c  than is the tube portion  24   c.  In the presently preferred embodiment, the mixing chamber  22  is in the form of cylindrical hollow tubular member that is sealed or closed with the exceptions of openings described. The mixing chamber has an axial length “1” along the axis A C  and has a diameter “d”. The cold and hot pipes  16 ,  18  are shown aligned with the vortex tube  12  axis A V , and the axes A C  and A V  are preferably relative to each other inclined at an angle α as shown. The angle α is 45° in the present preferred embodiment, although this angle may be varied considerably, with different degrees of advantage. It is also preferred that the cold air stream  36  be injected at a distance approximately 1.5-2 inches from the outlet to  38 . This distance can, also, be modified slightly with different degrees of advantage. The angle of 45° is generally preferred and provides improved results. Thus, while the high pressure air stream  34  generally enters along the axis A C  shown, the lower pressure cold air stream  36  as injected at angle of 45° relative to the high pressure stream  34 , the gas is being mixed within the mixing chamber and exit as a stream  40  that may be at higher pressure than the pressure of the stream  36  but it has been elevated temperature somewhat depending on the adjustment of the valve  26 , between the temperatures of the ambient and cold streams  34 ,  36  respectively. 
         [0037]    Referring now to  FIG. 3 , another present preferred embodiment of the invention is illustrated that is generally is designated by the reference numeral  10 ′. As it will be more fully described below, the difference between the device illustrated in  FIG. 2  and the one illustrated in  FIG. 1  is that the device illustrated in  FIG. 2  includes a temperature amplification device, utilizing a feedback loop, that is used for a lower temperature of the usable out-stream of gas. 
         [0038]    In  FIG. 2 , a pre-cooler housing  42  is provided that may be made of plastic or other temperature insulating or heat-flow resistant material. The pre-cooler housing  42  has an inlet opening  42   a  and an outlet opening  42   b,  shown at opposing or opposite sides of the housing. A pair of opposing openings  42   c  and  42   d  are provided that are arranged along a direction generally transverse to the direction of the openings  42   a,    42   b  shown. The pre-cooling housing  42  has an internal chamber, cavity or compartment  42   e  that serves as a heat exchange chamber, as it will become more evident from the discussion that follows. 
         [0039]    The mixer  22  is connected, at its inlet end with a bypass tube  24   b,    24   c  that is coupled to the valve  26 . As indicated, the valve  26  can be used to adjust the pressure and, therefore, the gas flow velocity from the inlet to the mixer chamber  22 . The cold air inlet tube  16  transfers the cooled air  36  from the cooled air end  12   a  of the vortex tube  12  as previously described. The high pressure gas  34  is mixed with the cooled air  36  and the mixed gas is channeled by means of pipe portions  38   a - 38   e  to the inlet opening  42   c  of the cooling chamber. The high pressure inlet tube  20  is now formed of spaced sections  20   x  and  20   y  that are aligned but spaced from each other along an axis of the high pressure inlet pipe. The inlet pipe portion  20   x  has a threaded end  20   x ′ that is connected, such as by bushing  46 , to a heat exchange tube or pipe  48  that has opposing threaded ends  48   a  and  48   b  that are respectively attached to the bushing  46 , at one end, and a coupling  50  that joins the threaded end  48  as well as a threaded end  21 ′ of the pipe portion  20   y.  It will be clear, therefore, that the high pressure gas entering the pipe portion  20   x  passes through the heat exchange pipe  48  and into the vortex tube  12  by means of a pipe or tube portion  20   y.  The gas in the pipes or tubes  38   a - 38   e  emanates from the mixing chamber  22  and is directed into the compartment or chamber  42   e  and exits as the cooled gas stream  40 . However, because the cooled air stream fills the chamber or compartment  42   e,  it absorbs some of the heat from the heat exchanger pipe or tube  48 , as it passes through the pre-cooler  42 , and ultimately is outputted for use in cooling objects. The heat exchanger  48 , therefore, becomes cooler in time, and high pressure gas that passes through pipe or tube portions  20   x,    20   y  through the pre-cooling chamber  42  is likewise cooled by the removal of heat. 
         [0040]    The operation of the device illustrated in  FIG. 2  will now be described. Initially, the high pressure gas P enters the tube portion  20   x  and is guided through the heat exchanger tube  48  and through the tube portion  20   y  into the vortex tube  12 . As all the temperatures are initially at ambient temperature, there is a little or not heat transfer to the initial stream of the high pressure gas stream as it enters the vortex tube. However, the cooled air stream  36  exiting from the cooled air outlet end  12   a  of the vortex tube is mixed with high pressure gas  34  in the mixing chamber  22 , as previously described. Since the high pressure gas stream  34  is typically at a higher temperature than the temperature of the cooled gas stream  36 , the gas stream  38  that exits the mixing chamber  22  tends to be at a temperature between of temperature of the high pressure gas and the cooled air stream. The mixing chamber  22 , therefore, elevates the temperature of the cooled air stream  36 , although that stream is now at a higher pressure. The cooled air stream that enters the pre-cooling chamber  42  lowers the temperature within that chamber and there is a transfer of heat due to the cooling effect of the heat exchanger tube  48 . As the heat exchanger tube  48  cools, high pressure has P passing through the heat exchanger tube  48  is pre-cooled before it enters the vortex tube  12  at the high pressure input pipe portion  20   y.  Such pre-cooled gas is then further cooled by the vortex tube  12  and this results in further cooling at the outlet of the mixing chamber  22 , and additional cooling of the heat exchanger tube  48 . Such a feedback-type arrangement continues to increasingly cool the heat exchanger tube  48  thereby resulting in a continued drop in temperature of the input gas pressure stream P prior to entry into the vortex tube  12 . The pre-cooling chamber  48  is, therefore, in the nature of an amplification device and it amplifies the cooling effect of the cooled output gas outputted by the vortex tube  12  and the gas exiting the mixing chamber  22 . This continues until an equilibrium is reached when the drop in the temperature in the pre-cooling chamber is such that decreases in temperature are compensated or offset by increases in heat transfer from the ambient atmosphere. 
         [0041]    Referring to  FIGS. 3 and 4 , the heat and temperature parameters can be explained in term of the device shown in  FIG. 2 . Thus, the inlet air at high pressure enters at heat level Q 1 . As indicated, initially, the pre-cooling chamber  42  is at ambient and there are no change in temperature as the high pressure gas passes through the heat exchange or transfer tube  48 . However, in time, the heat transfer tube  48  cools off and there is a change in heat −ΔQ 1  as the high pressure gas passes though the heat exchanger tube  48 . The gas passing through the heat exchanger tube  48  is modified, therefore, by a change in heat −ΔQ 1  as it enters the vortex tube  12 . The air in the vortex tube is further modified at the heated end by a decrease of heat −ΔQ 2  at one end and an increase in heat at the other end at +ΔQ 3 . The outlet of the vortex tube  12  is at a heat level Q 4  as it enters the mixing chamber  22  where the heat level is increased by +ΔQ 4 , due to the addition of and mixing with the high pressure gas at ambient emanating directly from the high pressure side. The heat level Q 5  at the inlet to the heat exchanger  48  may experience slight rise in heat removed from the ambient high pressure gas at Q 1 . However, because the flow of Q 5  is relatively high through the pre-cooling chamber  48  the heat level Q 6  is approximately equal to Q 5 . 
         [0042]    In  FIG. 4 , a transition is shown between the temperature T of the stream  40  over time after the device is activated. At t 1 , the temperature is at T 1 . As the cooled air  36  from the vortex tube  12  circulates through the mixing chamber  22  and the pre-cooling chamber  42 , there is a gradual drop in the temperature of the heat exchanger tube  48  and the amount of heat exchange results in a drop in temperature of the gas exiting the pre-cooling chamber  48  into the input pipe portion  20   y  of the vortex tube. The drop of temperature continues until time t 2  when the temperature has dropped to T 2 , where the temperature remains as long as the device operation is maintained. As indicated, the temperature does not drop below T 2  because a equilibrium state is reached between the amount of heat removed from the flowing gases and the amount of heat that is transferred to the device from the ambient atmosphere. Clearly, the greater the differential in the temperatures between the temperature T 2  and the ambient the greater the heat added from the ambient atmosphere and that is the reason why a steady state condition is reached in time. However, examining  FIG. 3  it will be clear that the differences in heat levels between the embodiments shown in  FIG. 2  is −ΔQ 1  imparted by the pre-cooling chamber  48 . The greater the efficiency of the pre-cooling chamber, therefore, the greater the quantity −ΔQ 1  and the greater the temperature drop in the outlet stream of cooled air  40 . Constructions to optimize the efficiency of the heat exchanger  42 ,  48  are well known to those skilled in the art. 
         [0043]    It would be obvious to those having skill in the art that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the present invention should, therefore, be determined only by spirit and the scope of the disclosure and the state of the prior art.