Abstract:
A vapor compression apparatus and a method for operating a vapor compression system are provided. A working fluid is conveyed through a vapor compression system having a fluid line. A magnetic field generator is connected to the fluid line to direct a magnetic field through the working fluid. The magnetic field is operable to disrupt intermolecular forces and weaken intermolecular attraction to enhance expansion of the working fluid to the vapor phase, increasing the capacity, performance and efficiency of the system components, and reducing system cycling, mechanical wear and energy consumption.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims priority under 35 U.S.C. §119 to U.S. Provisional Application No. 60/368,077 filed Mar. 27, 2002, which is hereby incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates to vapor compression systems, and more specifically to a vapor compression apparatus with magnetic components, and a method for enhancing the performance of heat pump and refrigeration equipment and the efficiency of vapor compression systems.  
         BACKGROUND  
         [0003]    In the present state of the art, vapor compression systems are used in a number of applications to cool an environment. Vapor compression is used in air conditioners, refrigerators, freezers, blast freezers and other cooling systems. Cooling is achieved by evaporating a refrigerant or refrigeration media under reduced pressure to lower the temperature of the refrigerant and absorb heat from an environment.  
           [0004]    In conventional vapor compression systems, refrigerants or refrigerant mixtures with low boiling points are used as the working fluid. The refrigerant is pumped to a compressor which elevates the temperature and pressure of the refrigerant. The hot refrigerant is discharged to a first heat exchanger, or condenser, to remove heat from the refrigerant. As heat is removed in the condenser at elevated pressure, the refrigerant converts to the liquid phase. The refrigerant is then conveyed to an expansion valve that rapidly reduces the pressure of the refrigerant. The rapid pressure reduction causes the refrigerant to flash into a liquid and vapor mixture having a very low temperature. The refrigerant is discharged to a second heat exchanger, or evaporator, where the refrigerant absorbs heat. The added heat converts a substantial portion of the remaining liquid phase to the vapor phase. The refrigerant is cycled back to the compressor, where the foregoing process is repeated.  
           [0005]    A significant problem with present vapor compression systems is the excessive cost of operation. Vapor compression consumes a significant amount of energy. Energy efficiency in vapor compression systems is often limited by incomplete or inefficient evaporation and condensation of the refrigerant. When evaporation is incomplete, some of the refrigerant enters the compressor shell in the liquid phase. The compressor must consume additional energy to boil the liquid refrigerant that enters the compressor shell. This reduces the coefficient of performance (COP) of system components and overall efficiency of the system.  
         SUMMARY OF THE INVENTION  
         [0006]    In a first aspect of the present invention, a vapor compression apparatus is provided that efficiently evaporates a working fluid to cool an environment. The working fluid is conveyed through a fluid line and passed through a compressor, a condenser, an expansion valve and an evaporator. One or more magnets are connected to the fluid line to generate a magnetic field through the working fluid. The magnetic field disrupts intermolecular forces in the working fluid and permits molecules in the liquid phase to disperse. The expanded molecules are more easily converted to the vapor phase, providing for more efficient evaporation. The apparatus is intended for use with various working fluids, and operable under various ranges of boiling and condensation temperatures to cover applications including, but not limited to, refrigeration, air conditioning, heat pumping and blast freezing.  
           [0007]    The present invention may be constructed and operated without the need for a highly skilled technician. In operation, the present invention increases the cooling capacity and COP of the evaporator. The present invention also reduces the amount of liquid fluid that enters the compressor shell, decreasing the power consumption by the compressor and reducing wear on compressor parts. In addition, the present invention improves system performance to reduce system cycling and limit wear on the condenser, evaporator and other components. The enhanced performance of the system and reduced cycling lowers overall power consumption in the system, conserving energy and lowering greenhouse gas emissions to the environment.  
           [0008]    In a second aspect of the present invention, a method for operating a vapor compression system is provided. As described above, a magnetic field is applied to a working fluid in a vapor compression system to disrupt intermolecular forces in the working fluid. The magnetic field is applied to the fluid before the fluid is conveyed through an expansion valve to enhance vaporization of the fluid. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0009]    The foregoing summary as well as the following description will be better understood when read in conjunction with the figures in which:  
         [0010]    [0010]FIG. 1 is a schematic view of an apparatus in accordance with the present invention.  
         [0011]    [0011]FIG. 2 is a fragmented perspective view of an apparatus in accordance with the present invention, illustrating one possible arrangement of magnets connected to a fluid line.  
         [0012]    [0012]FIG. 3 is a fragmented perspective view of an apparatus in accordance with the present invention, showing an alternate arrangement of magnets on the fluid line. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]    Referring to FIGS.  1 - 3  in general, and to FIG. 1 specifically, a schematic view of a vapor compression system in accordance with the present invention is shown and designated generally as  20 . The system  20  is operable to condense and evaporate a working fluid which flows through the system. A magnetic field is generated through the working fluid to enhance the coefficient of performance and energy efficiency of the system  20 .  
         [0014]    The vapor compression system  20  comprises a compressor  22 , a condenser  24 , an expansion valve  26  and an evaporator  28 . Depending on operating conditions, the system  20  may also incorporate other components used in vapor compression, including but not limited to a pre-condenser, post-condenser, pre-evaporator, post-evaporator, reversing valve, suction accumulator, and other components. The system  20  may use any type of heat exchanger in the condenser  24  and evaporator  28 , including but not limited to refrigerant/air, refrigerant/water or refrigerant/anti-freeze exchangers.  
         [0015]    A magnetic device  30  is connected to the system to create a magnetic field through the working fluid. The magnetic field is applied to the working fluid in the liquid phase to disrupt intermolecular forces in the working fluid and enhance expansion of the working fluid molecules. This reduces the amount of residual liquid that is boiled in the compressor shell, lowering the power consumption of the compressor and improving the overall efficiency of the system. The direction of flow of the working fluid in the system  20  is represented by the arrows in FIG. 1.  
         [0016]    The system  20  is intended to enhance the performance of a number of working fluids in vapor compression systems, including but not limited to pure refrigerants and multi-component HFC mixtures. The type of working fluid is dependent on, among other things, the desired application and operating temperatures for the condenser and evaporator. The present invention has been found to enhance performance of working fluids at condenser temperatures between 20° C. and 90° C., and evaporator temperatures between −85° C. and 25° C. The system  20  may be used with any pure refrigerant or refrigerant mixture, including but not limited to R-12, R-22, R-502, R-11, R-114, R-134a, R-507 (R-125/R-143a:50/50%), R-404A (R-125/R-143a/R-134a:44/52/4%), R-410A (R-32/R-125:50/50%), and R-407C (R-32/R-125/R-134a:23125/52%). In addition, ammonia, methane, ethane, propane, butane, pentane and carbon dioxide may be used as working fluids in the present invention. The foregoing list of refrigerants represents just some of the possible refrigerants that may be used, and is not intended to be exhaustive or exclude other refrigerants not explicitly mentioned. In the description that follows, the system  20  will be described simply as using a refrigerant, with the understanding that this may include a variety of pure refrigerants, multi-component HFC refrigerant mixtures, and other working fluids suitable for different applications.  
         [0017]    It has been found that magnetic enhancement of refrigeration media has performed best with multi-component HFC refrigerant mixtures, which are preferred in the present invention. Ternary refrigerant mixtures are most preferred. However, binary mixtures and pure refrigerants such as R-134A may also be used. Significant improvements in system performance have been found when magnetic enhancement is applied to systems using the R-404A and R-410A refrigerant mixtures. In particular, significant improvement in evaporator capacity has been observed when magnetic enhancement is used with R-404A. Significant improvement in condenser capacity has been observed when magnetic enhancement is used with R-410A.  
         [0018]    Referring now to FIGS.  1 - 2 , the system  20  will be described in greater detail. The system  20  is a closed loop system, in which the refrigerant is recycled. A fluid line  40  connects the compressor  22 , condenser  24 , expansion valve  26  and evaporator  28  in the closed loop. The magnetic device  30  comprises one or more magnets  32  that are held proximate to the fluid line  40 . The magnets  32  may be either permanent magnets or electromagnets. Various arrangements of magnets  32  may be used to generate a magnetic field through the fluid line  40 . For example, the magnets  32  may be made up of single-type or double-type magnets. In addition, the magnets  32  may have a unipolar or dipolar arrangement with respect to the fluid line  40 .  
         [0019]    The magnets  32  may be held in contact with the fluid line  40  using any type of connector or conduit arrangement. For example, the magnets may be secured to the fluid line  40  by a clamp that connects around the fluid line. Alternatively, the magnets  32  may be enclosed around a short section of conduit that is configured to be connected in line with the fluid conduit  40  using couplings, fittings or other technique. Although it is preferable to connect the magnetic device  30  to the fluid line  40  so that it directly contacts the fluid line, there may be a gap between the magnetic device and the fluid line. The magnetic device  30  simply must be sufficiently proximate the fluid line  40  to allow the magnetic field produced from the magnets to affect the working fluid.  
         [0020]    In FIG. 2, three magnets  32  are shown connected to fluid line  40 . Each magnet  32  is connected to the fluid line  40  with a clamp  34 . Each clamp  34  comprises a pair of plates that are connected together around the fluid line and a magnet. The plates hold the magnet in direct contact with the exterior of the fluid line. More specifically, the clamp  34  comprises a first plate  36  having a generally curved shape that fits around a magnet  32  and one side of the fluid line  40 , as shown in FIG. 2. The clamp  34  also comprises a generally flat second plate  38  placed on an opposite side of the fluid line  40 . The first plate  36  has a pair of outwardly extending flanges  37  that are configured to cooperate with a pair of ends  39  on the second plate  38 . The flanges  37  on first plate  36  and the ends  39  on the second plate  38  have bores that align with one another when the plates are placed around the fluid line  40 . The plates  36 ,  38  are held together in tight engagement by screws inserted through the bores as the bores are aligned. In this way, the plates  36 , 38  are configured to hold the magnet  32  securely against the exterior of the fluid line  40 . As stated earlier, the magnets may be arranged in a number of configurations relative to the fluid line  40 . The foregoing description and reference to FIG. 2 illustrates just one of the many arrangements that may be used in the present invention. For example, two curved plates similar to the first plates  36  in FIG. 2 may be clamped together around the fluid line  40  so that magnets are disposed on both sides of the fluid line.  
         [0021]    Evaporation of the refrigerant is enhanced by the application of an external magnetic field through the refrigerant in the liquid phase. Magnetic field energy has been found to alter the polarity of refrigerant molecules and disrupt intermolecular Van der Waals dispersion forces between refrigerant molecules. When the liquefied refrigerant is converted to vapor, intermolecular attraction caused by dipole interaction and Van der Waals forces must be overcome. The magnetic field affects the intermolecular attractions between neighboring molecules to permit the molecules to expand. More specifically, it is believed that the magnetic field weakens the intermolecular attraction between molecules in the refrigerant thereby allowing the molecules to expand more readily. This lowers the amount of energy required to drive the molecules apart, resulting in enhanced vaporization of the fluid.  
         [0022]    Magnetic fields are preferably applied to the refrigerant prior to flowing through the expansion valve  26 . In FIG. 1, the magnets  32  are shown connected to the fluid line  40  between the outlet of the condenser and the inlet of the expansion valve  26 . The magnets are positioned on the fluid line  40  so as to apply a magnetic field through a full liquid line before the fluid passes through the expansion valve  26 . The precise location where the refrigerant achieves a full liquid state after the condenser varies depending on the refrigerant, the size of the fluid line and operating conditions. Preferably, the magnets  32  are placed at a distance from the condenser outlet of between 20D and 120D, where D represents the outside diameter of the fluid line. Working fluids will typically be fully condensed in the liquid phase at this distance from the condenser outlet. The fluid line  40  between the condenser outlet and expansion valve inlet preferably has no fittings or transitions that could trap gas or interfere with condensation of the refrigerant. The line between the condenser outlet and expansion valve inlet may be vertical to assure that the fluid line passing through the magnetic field carries a full liquid flow without any trapped gas.  
         [0023]    As stated earlier, the magnets  32  may be either single-type or double-type magnets. Referring to FIG. 2, single-type magnets  32  are shown held against the fluid line  40  such that the polarity of each magnet is directed orthogonally to the flow direction in the fluid line; however, the polarity of magnets may be changed and still achieve acceptable results. The required number and arrangement of magnets will vary depending on operating conditions, including but not limited to the length of fluid line available to connect the magnets. A number of arrangements may be used in the present invention. For example, the present invention may utilize one relatively long magnet of low intensity, or a series of smaller magnets each having a larger intensity. Magnets  32  should each have a magnetic strength no less than 300 gauss. It has been found that enhancement of thermal capacities and COP of the system  20  increases as gauss levels are increased. Therefore, the magnetic strength of each magnet  32  is preferably no less than 2000 gauss, and more preferably no less than 4000 gauss. It has been found that three 4000 gauss magnets enhance vaporization of a refrigerant in a cooling system using a ⅜″ diameter conduit for the refrigerant. However, vaporization enhancement will also be achieved with other magnet intensities and conduit diameters. The magnets  32  may be formed of any suitable material or combination of materials, including but not limited to ferrites embedded in polymers.  
         [0024]    The magnets  32  may be clamped individually to the fluid line  40 , as described earlier. Alternatively, the magnets  32  may be interconnected and mounted to the fluid line  40  as an assembly. Referring to FIG. 3, magnets  32 A,  32 B and  32 C are interconnected on a threaded rod  50  and held in contact with fluid line  40 . The threaded rod  50  permits fine adjustment of the spacing between magnets on the fluid line  40  to alter the magnetic field characteristics. Magnet  32 A is anchored to the fluid line  40  in a fixed position by a clamp  34 . The threaded rod  50  is connected to the clamp  34  so that it is fixed relative to magnet  32 A. The rod  50  may be welded to the clamp  34  or inserted through a sleeve having threads that mate with the threads on the rod. Once magnet  32 A is clamped on the fluid line  40 , the rod  50  is configured to hold additional magnets in contact with the fluid line.  
         [0025]    In FIG. 3, magnets  32 B and  32 C are placed on the rod  50  on each side of magnet  32 A. Magnets  32 B and  32 C are each connected on the rod  50  by a sleeve  52 . Each sleeve  52  has a bore  54  adapted to receive the rod and permit the magnets to slide along the length of the rod. A pair of locknuts  56  are threaded onto the rod on each side of the sleeves on magnets  32 B and  32 C. When threaded on the rod, the locknuts  56  are axially displaceable on the rod by rotating the locknuts. The locknuts engage the sleeves to limit displacement of magnets  32 B and  32 C relative to the fluid line  40 . More specifically, the locknuts  56  are configured to be tightened against the sleeves  52  to retain the magnets  32 B and  32 C in fixed positions relative to the fluid line  40  and magnet  32 A. The magnets  32 B and  32 C are movable on the rod  50  when the locknuts are rotated out of engagement and away from the sleeves to provide clearance for the magnets to be moved on the rod. As such, the locknuts are configured to hold the magnets  32 B and  32 C in a fixed position on the rod  50 , and operable to increase or decrease the spacing between the magnets.  
         [0026]    The terms and expressions which have been employed are used as terms of description and not of limitation. There is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof. It is recognized, therefore, that various modifications are possible within the scope and spirit of the invention. Accordingly, the invention incorporates variations that fall within the scope of the following claims.