Abstract:
A method and at least two devices demonstrate improvements to energy extraction from a compressible rotation working fluid in a liquid ring heat engine, which has a rotor mounted in a case. A space in the case is occupied by a liquid that establishes a liquid ring piston for the rotor. The rotor defines at least a first and a second operating zone. In the first zone, the working fluid is expanded against the liquid and, in the second zone, the working fluid is re-compressed. Between the two zones, the working fluid is cooled. In one device, the cooling step occurs on the rotor in a third zone. In another device, the cooling occurs outside of the case.

Description:
TECHNICAL FIELD  
       [0001]    The embodiments disclosed herein relate to an improved liquid ring device for converting thermal energy in the nature of a working fluid into practical mechanical work. More particularly, the improved liquid ring device as described herein incorporates more than one thermodynamic action with the working fluid, including a cooling zone in which the working fluid is cooled. 
       BACKGROUND 
       [0002]    The liquid ring device is known in the prior art, with the concept existing in the patent art at least as early as U.S. Pat. No. 1,094,919 to Nash in 1914. In the Nash &#39;919 device, a combustible gas is introduced into the device, compressed and ignited, with the expansion being used to provide mechanical energy. 
         [0003]    In some situations in the prior art, the liquid ring device is used to compress gases at the expenditure of mechanical energy, while, in another type of operation, it is used as an expander to extract thermal energy from a working fluid as practical mechanical work. One application is the recuperation of the energy carried out by the exhaust gases from an internal combustion engine or a gas turbine. 
         [0004]    Many other applications are envisioned, in which different working fluids are used. These include, but are certainly not limited to, recuperation processes involving furnace gases, foundry gases, residual industrial steam or geothermal gases, such as from a volcano. In yet other applications, the liquid ring device can be used as a prime mover or stand alone heat engine in conjunction with a hot gas generator of a suitable type. In general, the device is able to operate effectively, once the mode of operation and the energy source has been selected. 
         [0005]    It is, however, not known in the prior art to perform more than one thermodynamic transformation in a single liquid ring device. 
       SUMMARY  
       [0006]    This and other unmet advantages are provided by the device and method described and shown in more detail below and as claimed in the appended claims. 
         [0007]    This and other advantages are achieved by a liquid ring heat engine (LRHE) that extracts energy from a working fluid. The LRHE has a cylindrical case; a rotor, arranged for rotation on a shaft that is eccentrically mounted inside the cylindrical case; a space, internal to the cylindrical case, for receiving an amount of liquid that effects a piston ring around the rotor as the rotor rotates on the shaft relative to the cylindrical case, as well as an inlet and an outlet for the working fluid. The rotor defines, on a face thereof, a first zone where the working fluid is expanded and a second zone where the working fluid is compressed. To achieve this, a plurality of vanes are arranged in spaced-apart relationship, on at least one of the rotor faces. 
         [0008]    In one embodiment, the plurality of vanes are arranged symmetrically on only one face of the rotor, and, in this embodiment, each of the first and second zones is located on the face of the rotor on which the vanes are arranged. 
         [0009]    In this embodiment, the rotor further defines a third zone, positioned in a rotational sense between the first and second zones; with a means for cooling the working fluid operatively arranged in the third zone. 
         [0010]    In another embodiment, the plurality of vanes are arranged symmetrically on each of the two faces of the rotor, with the first and second zones located on the respective first and second faces of the rotor. 
         [0011]    In this second embodiment, the LRHE further comprises an intermediate outlet for the working fluid, a means for cooling, located external to the cylindrical case, and an intermediate inlet for the working fluid. The intermediate outlet, the cooling means and the intermediate inlet define a conduit such that the working fluid exits the first zone, passes through the cooler and enters the second zone. 
         [0012]    In the first embodiment, the inlet and outlet are each arranged radially with respect to the shaft. 
         [0013]    In the second embodiment, the inlet and the intermediate outlet are arranged radially with respect to the shaft, but the intermediate inlet and the outlet are arranged axially with respect to the shaft. 
         [0014]    In the second embodiment, the LRHE also comprises a flange, inside the cylindrical case, that coacts with the rotor to effectively divide the internal space of the cylindrical case into an expander portion and a compressor portion. 
         [0015]    In at least the first embodiment, the LRHE further comprises a sealing surface, in fixed angular position relative to the to the rotor, operating with the vanes and rotor face to trap the working fluid inside the rotor during the expansion thereof in the first zone. The LRHE can also comprise a sealing surface, in fixed angular position relative to the to the rotor, that operates with the vanes and rotor face to trap the working fluid inside the rotor during the compression thereof in the first zone. 
         [0016]    The advantages are also achieved by a method of extracting energy from a compressible working fluid. In the method, the working fluid is injected into a LRHE comprising a rotor that defines at least a first and a second zone. The injected working fluid is expanded against a liquid in the first zone and recompressed in the second zone, after which the recompressed working fluid is discharged from the LRHE. 
         [0017]    In many of the embodiments of the method, the working fluid is rapidly cooled between the expanding step and the re-compressing step. In some of these methods, the step of rapidly cooling the expanded working fluid occurs in a third zone of the rotor positioned, in a rotational sense, between the first and second zones. In other of these methods, the step of rapidly cooling the expanded working fluid occurs by several substeps, including removing the expanded working fluid from the first zone, passing the removed working fluid through means for cooling that is external to the LRHE and reinjecting the cooled working fluid into the second zone of the LRHE 
         [0018]    In an improvement to known LRHE technology for extracting energy from a working fluid, the improvement is found in arranging a first zone in which the working fluid is expanded and a second zone where the working fluid is compressed in the same LRHE case 
         [0019]    In many of these improved LRHEs, the improvement also has a third zone, positioned in the case between the first and second zones, where the working fluid is cooled. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    A better understanding of the disclosed embodiments will be obtained from a reading of the following detailed description and the accompanying drawings wherein identical reference characters refer to identical parts and in which: 
           [0021]      FIG. 1  is a sectional view looking down a major axis of a first embodiment of a liquid ring heat engine; 
           [0022]      FIG. 2  is a side sectional view, taken along a major axis, of a second embodiment of a liquid ring heat engine; and 
           [0023]      FIG. 3  is a pressure-volume diagram depicting the operation of the liquid ring heat engines according to both  FIGS. 1 and 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    The embodiments of the inventive concept are based on the liquid ring compressor/expander concept, which is known in the prior art. As will be seen, the disclosed embodiments provide some different elements and require different operation. The “conventional” liquid ring machine of the prior art has only two ports. In the first port, the gaseous working fluid enters through a gas inlet. Once the working fluid either has energy extracted or added, depending upon the selected mode of operation, the working fluid leaves the device through a gas outlet. There are several possible implementations, but in all of the known implementations, an angular region (in the sense of rotation) is located between the respective inlet and outlet. This angular region allows time and space for the working fluid to be expanded or compressed, according to the machine function. 
         [0025]      FIG. 1  depicts a schematic sectional view looking down the major axis of symmetry of a first embodiment  10  of a liquid ring heat engine. A rotor or impeller  20  is located inside a cylindrical case  30 . Rotor  20  will typically be provided with a plurality of spaced-apart vanes  22 , which are preferably symmetrically arranged, on a working face  24  of the rotor. A shaft  40  sustains the rotor  20 , to which the shaft is coupled. The shaft  40  is eccentrically located with respect to an axis of symmetry of the case  30 . Depending upon the application, case  30  may also be arranged to allow for it to rotate about its own axis of symmetry, for augmented system efficiency. The power output is taken from rotor  20 , which may also turn the case  30  with equal or different speeds by suitable means. As depicted and described, the embodiment  10  operates by counterclockwise rotation. A frame (not shown) can provide a rigid and fixed means to receive the shaft  40 . The mechanical arrangement, the shape of the vanes and related dimensions have been developed in, and can be found in, the prior art. 
         [0026]    Beyond the strictly structural elements, an amount of a liquid is placed in the case  30 , where it resides in an internal space  32  of the case. As is known from the prior art, the liquid effects a piston ring around rotor  20 , due to centrifugal force from the spin of the rotor and especially of the vanes  22 . While a rather small spin is enough to shape the liquid into the piston ring configuration, optimal functioning relative to the working pressure and geometry requires a typical tip speed at or above 10 m/s for the vanes  22 . When case  30  is also being driven or is arranged for free rotation, even higher tip speeds may be desired. 
         [0027]    Inside the shaft  40 , a first conduit  42  supplies the energized or fresh working fluid to the working face  24 . A second conduit  44  removes the expended working fluid from the working face  24 . The respective conduits  42 ,  44  are separated from each other by a septum  46  which represents a top dead center (“TDC”) position for rotor  20 . 
         [0028]    A third conduit  48  in shaft  40  supplies cooling liquid under pressure to a cooling means, depicted here as a cooler  50  having multiple nozzles. In practice, the cooler  50  will have an array of cooling sprays  52  as a result of the multiple nozzle arrangement, but only one is depicted in  FIG. 1 , to not complicate the drawing. 
         [0029]    It will be typical and common to use the same liquid for cooling as is used in the internal space  32  to effect the piston ring, but there may be reasons in some application to not rigidly do this. However, use of the same liquid provides quite obvious advantage by eliminating a need for separation. 
         [0030]    Turning now to the operation of the embodiment  10 , the energetic working fluid enters the embodiment along the shaft  40  in first conduit  42  and passes through an inlet port  54  in the shaft onto a space in the rotor  20  that is defined by a pair of adjacent vanes  22 , rotor face  24  and the piston ring provided by the fluid. In principle, the pressure inside the portion of the rotor  20  in communication with inlet port  54  is constant and equals the pressure existing in second conduit  44 . 
         [0031]    In terms of rotational direction, which is counterclockwise in  FIG. 1 , a first sealing surface  60  is located beyond the port  54 . This first sealing surface  60 , which is angularly fixed in place and does not rotate with the rotor  20 , operates with the vanes  22 , rotor face  24  and liquid piston ring to trap the working fluid inside the rotor  20 . This geometry allows the working fluid to expand to a lower pressure and higher volume. As a practical point, the final expansion pressure should be as low as possible below the atmospheric pressure, perhaps limited only by cavitations. 
         [0032]    As noted in  FIG. 1 , the depicted first sealing surface  60  extends rotationally to approximately the bottom dead center (BDC”) of the rotor  20 , with the angular distance between the beginning of the inlet port  54  to the end of the first sealing surface  60  generally defining a first zone of operation in which the working fluid is expanded. 
         [0033]    Past the first sealing surface  60 , using the rotational sense, a cooling zone is encountered by the trapped and now-expanded working fluid. In principle, the pressure inside this portion of the rotor  20  in communication with the cooling zone is constant and close to the final expansion pressure. The cooler  50  is arranged to spray cooling liquid into the cooling zone, removing heat from the working fluid. In the cooling zone, the pressure of the working fluid is reduced while the volume remains substantially constant. This process continues until the rotor  20  moves the trapped portion of working fluid past the cooling zone. 
         [0034]    At the end of the cooling zone, a second sealing surface  62  is angularly fixed in place and serves to continue to trap the working fluid, along with the rotor face  24 , the vanes  22  and the liquid piston ring. This new zone, which continues angularly through the point where the working fluid is exhausted from the embodiment  10 , is a compression zone. The working fluid is compressed to, or at least close to, atmospheric pressure. Once past the second sealing surface  62 , the working fluid can pass through outlet port  56  in the wall of shaft  40 . From there, the expended working fluid passes into second conduit  44 . 
         [0035]      FIG. 2  represents another embodiment  210  of a liquid ring heat engine. Rather than dividing a face of the rotor into a first zone where expansion occurs and a second zone where re-compression occurs, as well as an intermediate cooling zone, the rotor  220  has a first face  224  where the expansion occurs and a second face  226  where the re-compression occurs, with an intermediate cooling step that occurs external to the case  230  in which the rotor is contained. Each face  224 ,  226  is appropriately arrayed with vanes  222 ,  228 . The vanes  222 ,  228  are symmetrically arranged on the respective faces, but the number of vanes may vary on each face of the rotor  220 . 
         [0036]    As before, the rotor  220  is contained in the interior  232  of case  230 . Since the sectional depiction cuts through rotor  220  looking from a point representing top dead center, the eccentric placement of the rotor in the case is not seen, but this is an inherent feature of the liquid ring heat engine, as is the liquid which provides the liquid piston ring. An internal flange  234  that runs circumferentially inside case  230  effectively divides the case interior  232  into an expansion portion  236  and a re-compression portion  238 . In many embodiments, it will be very desirable to provide a series of small passages  235  through flange  234 , to allow equilibration of the piston liquid in each of the portions  236 ,  238 . 
         [0037]    The energetic working fluid passes along shaft  240  in conduit  242 . Inlet port  248  allows the working fluid to radially enter the expansion portion  236 , where the working fluid expands in a volume defined by a pair of vanes  222 , the rotor face  224 , a rotor top surface  225  and the liquid piston. After moving around the expansion portion  236 , the expanded working fluid leaves the expansion portion in a radial direction through an intermediate outlet  272 , through a conduit  274  and into a cooling means  250 , where the working fluid is cooled. 
         [0038]    Leaving the cooling means  250 , conduit  276  injects the working fluid into intermediate inlet  278 , which is depicted in  FIG. 2  as an axial insertion into recompression portion  238 . In the re-compression portion  238 , the working fluid is recompressed in a volume defined by a pair of vanes  228 , the rotor face  226 , a rotor bottom surface  227  and the liquid piston. After moving around the re-compression portion  238 , the working fluid leaves axially through outlet  256 , through a conduit  244 . 
         [0039]      FIG. 3  illustrates, in an idealized thermodynamic pressure versus volume representation, how the working fluid is handled in the embodiments described herein. 
         [0040]    For exemplary purposes only, the working fluid passes through a very well known ideal Otto cycle, represented by segments  302 ,  304 ,  306  and  308 , to increase the pressure and volume of the working fluid from that represented by point  0  to that represented by point  4 . This Otto cycle is used as a “support cycle”. Because the heat engine is conceived as a device for converting thermal energy from a high enthalpy gas, the operation of the heat engine is independent from the specific nature of the support cycle and of the type of gases used. Starting, then, at the thermodynamic state represented at point  4 , which represents the end of the expansion stroke of the support cycle, the hot gases are discharged by the exhaust port of the support cycle engine and injected into the heat engine through appropriately-sized ducts. 
         [0041]    Once in the heat engine, such as embodiment  10 , the hot gases undergo the expansion represented by segment  310  in the first zone described relative to  FIG. 1 , the working fluid arriving at the condition indicated by point  5 . In the cooling zone that angularly follows in the  FIG. 1  embodiment  10 , the rapid cooling of the working fluid by means of water spray injection or other suitable cooling process decreases the pressure while not affecting volume, taking the working fluid to point  6  along segment  312 . Finally, as the working fluid enters the compression zone that is associated with sealing surface  62 , the working fluid is recompressed along segment  314 , arriving back at point  1 . From here, the discharge of the working fluid occurs along segment  302 , but in the opposite direction of the first step in the process. 
         [0042]    The same process can be understood as occurring in relation to the  FIG. 2  embodiment. Again starting in the heat engine at point  4 , the expansion step  310  in the case&#39;s expansion portion  236  is followed by the cooling step  312  in the external cooler  250  and the compression step  314  occurs in the case, but on the opposing side of the rotor, in re-compression portion  238 . 
         [0043]    Having shown and described a preferred embodiment of the invention, those skilled in the art will realize that many variations and modifications may be made to affect the described invention and still be within the scope of the claimed invention. Thus, many of the elements indicated above may be altered or replaced by different elements which will provide the same result and fall within the spirit of the claimed invention. It is the intention, therefore, to limit the invention only as indicated by the scope of the claims.