Abstract:
A distributed refrigeration system has a temperature controlled case configured to store and display objects in a facility, a first coolant adapted to cool the objects and circulate through a first cooling system configured to operate with the case, and a second cooling system communicating with the first cooling system to receive a second coolant for removing heat from the first coolant. A method of providing a distributed refrigeration system for delivery to a facility includes providing a temperature-controlled case to store and display objects within a facility, assembling a self-contained first cooling system with the case to circulate a first coolant to cool the objects, and providing a second cooling system communicating with the first cooling system, the second cooling system having a supply connection and a return connection to circulate a second coolant to remove heat from the first coolant.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a refrigeration system. The present invention relates more particularly to a distributed refrigeration system.  
         BACKGROUND  
         [0002]    It is generally known to provide refrigeration systems for commercial or institutional food sales or food service facilities such as supermarkets, grocery stores, cafeterias, etc. These refrigeration systems operate with refrigeration or cooling devices such as temperature controlled cases (individually or in groups) that use air-cooled or water-cooled condensers supplied by a rack of compressors. For example, modern supermarket applications typically have many individual or grouped refrigeration devices located throughout the shopping or display area of the supermarket. Each refrigeration device is provided with a cooling interface such as an evaporator or cooling coil that receives refrigerant from the refrigeration system in a closed loop configuration where the refrigerant is expanded to a low pressure and temperature state for circulation through the cooling interface to cool the space and objects within the refrigeration device. In such applications, one or more condensers are typically located either outside, on the roof, or in a machine room or back room adjacent to the shopping or display area where the refrigeration devices are located and are used to cool the refrigerant that is distributed to all or a group of these refrigeration devices.  
           [0003]    In such known refrigeration systems, extensive networks of refrigerant piping are often required to interconnect the remotely located condensers to the cooling interfaces of the various refrigeration devices. These networks of refrigerant piping are often expensive to construct and maintain and are usually coordinated with the construction of the facility since the piping is often insulated and concealed by routing through the floors, ceilings, or walls of the facility to avoid exposure within the shopping area of the facility. Such known systems require numerous joints and other connections that are typically field run, installed and tested, and are subject to potential leakage concerns. Such extensive networks of refrigerant piping also require large quantities of refrigerant that must be charged after piping installation in order to properly operate in a closed loop manner over the extended distances of the network. Generally, the longer the piping network, the more refrigerant required and the greater the potential for leakage which creates adverse environmental concerns within the facilities. The concealed nature of the networks provides further difficulty in maintaining the systems due to the difficulty of locating, accessing and repairing piping leaks. Such refrigerant networks also complicate replacement and relocation of the refrigeration devices within the facility due to the substantially permanent routing of the refrigerant piping and its integration within the facility.  
           [0004]    Efforts have previously been made to address these deficiencies. For example, modular refrigeration systems are generally known, such as those described in U.S. Pat. No. 5,743,102 titled “Strategic Modular Secondary Refrigeration” issued on Apr. 28, 1998. Such modular systems typically provide a single rack unit having compressors and a condenser having a smaller piping network for connection to a group of refrigeration devices (for example, five (5) or six (6) located in a particular zone of the facility). In such modular systems, a secondary coolant may be circulated through a second, non-refrigerant piping system having a coolant such as water or a propylene glycol mixture to transfer heat from the local condenser to a remotely located chiller unit. Such known modular refrigeration systems also require field run and assembled refrigerant piping along with the corresponding additional fittings and connections necessary for supplying multiple refrigeration devices. Further, such conventional and modular systems often require separately wiring the various components of the refrigeration device upon installation in the facility, such as wiring for compressor power, control devices, lights, electric defrosting heaters, etc. As recognized in the 5,743,102 patent, it generally has not been considered feasible to provide self-contained refrigerated devices or merchandisers for stand-alone operation in a supermarket or other setting for reasons, among others, including high cost, low energy efficiency, and an unacceptably high noise volume from the compressors.  
           [0005]    Accordingly, it would be advantageous to provide a distributed refrigeration system having a stand-alone refrigeration device with a self-contained refrigeration system that is suitably efficient for commercial viability. It would be further advantageous to provide a distributed refrigeration system having a sufficiently low noise level for use in supermarkets or other consumer-oriented facilities. It would also be advantageous to provide a distributed refrigeration system that reduces the amount of refrigerant and refrigerant piping within a facility to reduce environmental hazards and to reduce installation costs, complexity, maintenance and repair time. It would also be advantageous to provide a distributed refrigeration system having a refrigerant piping system limited to a particular refrigeration device and capable of having all refrigerant piping installation and connections made and pre-charged in a factory setting to minimize installation time and complexity, and to improve flexibility in retrofit applications. It would be further advantageous to provide a distributed refrigeration system having a central electrical unit in which all electrical functions of the distributed refrigeration unit are pre-wired at the factory and require only a single electrical power hook up when installed at a facility.  
           [0006]    Accordingly, it would be advantageous to provide a distributed refrigeration system having any one or more of these or other advantageous features. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a schematic diagram of a conventional refrigeration system.  
         [0008]    [0008]FIG. 2 is a schematic diagram of a distributed refrigeration system according to a preferred embodiment.  
         [0009]    [0009]FIG. 3A is a perspective view of a refrigeration device for a distributed refrigeration system according to a preferred embodiment.  
         [0010]    [0010]FIG. 3B is a side view of a refrigeration device for a distributed refrigeration system according to a preferred embodiment.  
         [0011]    [0011]FIG. 4 is a perspective view of a portion of a refrigeration device for a distributed refrigeration system according to a preferred embodiment.  
         [0012]    [0012]FIG. 5 is a schematic view of an electrical and control system for a distributed refrigeration system. 
     
    
     SUMMARY  
       [0013]    The present invention relates to a distributed refrigeration system and includes a temperature-controlled case configured to store and display objects in a facility, a first coolant adapted to cool the objects and circulate through a first cooling system configured to operate with the temperature controlled case, and a second cooling system in thermal communication with the first cooling system, where the second cooling system is adapted to receive a second coolant for removing heat from the first coolant.  
         [0014]    The present invention also relates to a method of providing a distributed refrigeration system for delivery to a facility and includes providing a temperature controlled case adapted to store and display objects within a facility, assembling a self-contained first cooling system with the temperature controlled case, the first cooling system adapted to circulate a first coolant to cool the objects, and providing a second cooling system in thermal communication with the first cooling system, where the second cooling system has a supply connection and a return connection to circulate a second coolant to remove heat from the first coolant.  
         [0015]    The present invention further relates to a stand-alone temperature controlled case for a supermarket and includes an enclosure for storing and displaying objects, a self-contained first cooling system having a first coolant, where the first cooling system is coupled to the enclosure and adapted for exclusive use with the enclosure, and a second cooling system coupled in thermal communication to the first cooling system and adapted to receive a second coolant from a second coolant supply source for removing heat from the first coolant.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]    Referring to FIG. 1, a conventional supermarket refrigeration system is shown. As previously discussed, it is conventional practice to place the compressors  10  and the condenser  12  in a location remote from the refrigeration or cooling devices  16 . In this conventional arrangement, the compressors  10  are configured in a parallel bank located in an equipment room or on the roof or other remote area of the facility separate from the shopping or display area. The compressors supply a relatively large condenser  12 , which may be air or water cooled. The condenser  12  supplies liquid refrigerant to a receiver  14 , which provides a condensed refrigerant reservoir for supplying liquid refrigerant to the individual refrigeration devices located throughout a shopping or display area within the facility through a refrigerant piping supply network  20 . The refrigerant is expanded in an expansion device (not shown) and directed through an evaporator  18  in each of the refrigeration devices  16 , where the refrigerant vaporizes as it receives heat from the space and any objects within the refrigeration device. The compressors extract the refrigerant vapor by suction through a refrigerant return piping network  22 , and compress the refrigerant back to a liquid state where it is then cooled in condenser  12 , whereupon the cycle continues. The refrigerant supply and return piping networks  20 ,  22  are field-run and often routed at least partially through concealed areas of the facility such as floors, walls, ceilings, etc. and have numerous joints, couplings, fittings and other connections (not shown).  
         [0017]    Referring to FIG. 2, a distributed refrigeration system is shown according to a preferred embodiment. Distributed refrigeration system  30  may be provided for a single cooling device  32  or may include multiple cooling devices or temperature controlled cases (shown schematically as a low temperature cooling device  34  such as a freezer unit and a medium temperature cooling device  36  such a refrigeration unit) located in a shopping or display area  52  of a facility  50  (e.g. supermarket, grocery store, hotel, restaurant, cafeteria, etc.). In a particularly preferred embodiment, each cooling device includes an enclosure for storing or displaying objects in a spaced that is cooled by a direct expansion refrigeration system having an expansion device  38 , a cooling interface  40  (e.g. heat exchanger, evaporator, platform with coolant flow passages, etc.) a compressor  42 , and a condenser  44 . The refrigeration system is provided as a self-contained unit for exclusive use with a particular cooling device  32 , where cooling interface  40  and expansion device  38  are provided within cooling device  32  and compressor  42  and condenser  44  are mounted on or externally to cooling device  32  (shown schematically, for example, as mounted on a top portion of the cooling device). The condenser of cooling device  32  is cooled by a secondary coolant loop  60  using a liquid coolant, such as mixture of water and inhibited propylene glycol. The secondary coolant loop  60  communicates with a remotely located cooling device, shown schematically as a chiller  62 , located away from the cooling devices in a remote area  54  (e.g. equipment room, machine room, roof top, etc.). An electrical system, as shown in FIG. 5, is provided to operate and control the various electrical components of the distributed refrigeration system and includes, among others, a controller, solenoid valves, temperature sensors, switches, compressor motor and control relays and contactors, cabinet lighting within the cooled space of the cooling device, timers, fan motors and control switches, anti-sweat heaters and electric defrost heating elements. In an alternative embodiment, the compressor and condenser may be mounted in a lower portion of the cooling device, such as on a slide-out unit for ease of access and maintenance.  
         [0018]    Referring to FIGS. 2, 3A and  3 B, the refrigeration system  30  is provided as a self-contained unit for exclusive use with each cooling device. The expansion device  38  and cooling interface  40  may be located in any advantageous location within cooling device  32  for communication with the space and objects or products (not shown) to be cooled and the compressor  42  and condenser  44  are provided in a location that does not interfere with the space or cooling functions of cooling device  32 . In a particularly preferred embodiment, the expansion device  38  and cooling interface  40  are located in a lower portion of cooling device  32  and compressor  42  and condenser  44  are located on a top panel  46  of cooling device  32 . Fans (not shown) may be provided near cooling interface  40  to distribute cooled air from cooling interface  40  within cooling device  32 . The expansion device  38 , cooling interface  40 , compressor  42  and condenser  44  are interconnected in a closed loop configuration by a local refrigerant piping system  48  to form a primary cooling loop. In a particularly preferred embodiment, the expansion device  38 , cooling interface  40 , compressor  42  and condenser  44  and piping system  48  are pre-assembled and installed on cooling device  32  in a factory setting for shipment as a stand-alone unit to facility  50 . In an alternative embodiment, the cooling system components and piping may be custom configured and installed at the facility to suit customer preferences.  
         [0019]    The refrigerant piping system contained locally at the refrigeration system minimizes the amount of refrigerant piping and corresponding refrigerant required to operate the cooling device  32 , and minimizes the number of joints or connections in piping system  48 . Further, the ability to pre-assemble, pre-test and pre-charge the relatively smaller piping system  48  and components in a factory setting tends to improve the quality and integrity of the joints to minimize future potential refrigerant leakage. The location of the refrigerant piping solely at cooling device  32  also helps to improve the ability to locate any leakage that may develop within piping system  48  and the accessibility of the piping improves the ability to repair such local leakage quickly and cost-effectively. In conventional back-room or modular refrigeration piping networks the amount of refrigerant necessary to charge and operate the systems is substantially greater than the amount of refrigerant required by the distributed refrigeration system. Accordingly, substantial leakage in conventional systems may occur before being detected, whereas the smaller amount of refrigerant used by the distributed refrigeration system results in both a smaller quantity of refrigerant available for loss by leakage and the may increase the likelihood that leakage would be more readily detectable due to its more rapid impact on the performance of cooling device  32 , thereby reducing the effects of any leakage associated with the distributed refrigeration system.  
         [0020]    Referring further to FIG. 2, the compressors  42  at both the low temperature cooling device  34  and the medium temperature cooling device  36  are each sized correspondingly smaller than compressors used with conventional back-rom or modular systems due to the reduced cooling demand dictated by the standalone nature of the distributed refrigeration system. Such smaller compressor sizes may operate at lower efficiencies than the larger compressors of the more conventional systems. However, the smaller compressors  42  of the distributed refrigeration system are capable of operating with a lower refrigerant condensing temperature than the refrigerant condensing temperatures of the conventional systems. In a particularly preferred embodiment, the refrigerant condensing temperature at condenser  44  is in the range of approximately fifty (50) degrees F. to sixty (60) degrees F. (however, other suitable temperature ranges may be used in alternative embodiments). This lower condensing temperature, relative to conventional systems, provides for the use of relatively warmer secondary coolant temperatures at the condenser than are typically considered feasible for conventional low temperature refrigeration devices. In a particularly preferred embodiment, the lower refrigerant condensing temperature associated with the smaller compressor size of the distributed refrigeration system corresponds to a secondary coolant temperature (supplied by another cooling device, such as chiller  62 ) at the condenser  44  in the range of approximately twenty (20) degrees F. to fifty (50) degrees F. (however, other suitable temperature ranges may be used in alternative embodiments). This temperature requirement is within the operational range of conventional water-glycol solutions for applications below thirty (30) degrees F. and conventional water coolant for applications above thirty (30) degrees F. to provide an alternative to the use of chemicals such as potassium acetate or potassium formate that are often required in conventional systems having lower coolant temperature design requirements. The chiller may be an existing chiller already existing at the facility for use with medium temperature units, or alternatively, may be a custom-sized chiller designed for use with multiple distributed refrigeration systems intended for use at the facility.  
         [0021]    In a particularly preferred embodiment, condenser  44  is a shell and coil type condenser that reduces the required amount of refrigerant charge and the amount of refrigerant flashing, and also preferably avoids the need for a receiver. Since refrigerant contained in the receiver of a conventional system tends to gain heat from the surrounding ambient environment, the additional heat tends to reduce the efficiency of conventional systems. Accordingly, in a particularly preferred embodiment, the absence of a receiver from the distributed refrigeration system tends to improve the comparative efficiency of the distributed refrigeration system. In addition, the lower condensing temperature of the distributed refrigeration system provides efficiency gains over the conventional systems having higher condensing temperatures. These collective efficiency gains help to offset efficiency losses that may result from the use of a relatively smaller compressor  42  in the distributed refrigeration system.  
         [0022]    Referring further to FIG. 2, the secondary coolant system  60  for the distributed refrigeration system is shown according to a preferred embodiment. Secondary cooling system  60  includes chiller  62 , which is shown located away from the shopping or display area  52 , such as in a remote area  54 , such as an equipment room, machine room, roof top location or other convenient location. The chiller  62  provides a source of chilled coolant to remove the heat load from condenser  44  at cooling device  32 . The secondary cooling loop  60  has a supply side  64  and a return side  66 . The supply and return side may have a single branch directing secondary coolant to and from a single cooling device, or may have multiple parallel branches for directing secondary coolant to multiple cooling devices (shown schematically for example as two branches and refrigeration devices in FIG. 2). The branch lines may be routed to the distributed refrigeration system in any convenient manner and connected to corresponding inlet location  45  and outlet location  47  (shown schematically on FIG. 4) to condenser  44 . In a particularly preferred embodiment, flexible hoses are used to connect the secondary coolant supply and return lines to the inlet and outlet of condenser  44 . Accordingly, the distributed refrigeration system provides a self-contained direct expansion refrigeration system in a stand-alone cooling device that may be located at any convenient location within a facility and requires only the routing of a secondary coolant supply and return line to the condenser and connection of electrical power. In an alternative embodiment, conventional piping (e.g. copper, PVC, etc.) may be used in place of the flexible hoses to connect the secondary coolant supply and return lines to the inlet and outlet of condenser.  
         [0023]    Referring to FIG. 4, the condenser and compressor assembly for the distributed refrigeration system is shown according to a preferred embodiment. In a particularly preferred embodiment, compressor  42  is a semi-hermetic type compressor such as those commercially available from Copeland Corporation of Sidney, Ohio. The compressor  42  provides a suction source for removing the refrigerant from cooling interface  40 . The compressor  42  includes a high pressure switch  86  and a low pressure switch  88  (shown schematically in FIG. 5) that operate to stop compressor  42  when the refrigerant pressure is above a predetermined set point indicative of an overload condition, and when the refrigerant pressure is below another predetermined set point indicative of a vacuum condition. The condenser  44  is preferably a shell and coil type condenser such as those commercially available from the Standard Refrigeration Company of Melrose Park, Ill. The condenser  44  cools the compressed refrigerant to a temperature within the range of approximately forty-five (45) to fifty (50) degrees F. A regulating valve  68  senses the pressure of the refrigerant in the compressor and regulates the secondary coolant flow through condenser  44  according to compressor demand to maintain the condensed refrigerant within the desired temperature range. In a particularly preferred embodiment, valve  68  is a pressure actuated coolant regulating valve, model V46AC-1 of a type commercially available from Penn/Johnson Controls. A compressor refrigerant suction valve  84  (such as a manual shut-off valve) is provided for use in activities such as charging the refrigerant piping system  48 . In an alternative embodiment, a balancing valve may be used to control the coolant flow. In other alternative embodiments, other components or component types such as a scroll-type compressor, or other condensed refrigerant temperature ranges may be used having suitable characteristics for operating as a stand-alone distributed refrigeration system.  
         [0024]    Referring to FIG. 5, the electrical and control system components of the distributed refrigeration system are shown according to a preferred embodiment. Electrical and control system  70  includes compressor motor controls, relays, switches, contactors, transformers, defrost devices (e.g. electric heating elements, etc.), lights, compressor motor wiring, solenoid valves, sensors, etc. In a particularly preferred embodiment, the electrical and control system components are pre-wired in a central electrical and control unit configured for a single electrical power supply connection during installation at the facility. The electrical system may be configured to receive any conventional power supply at a facility such as 208 volt, three (3) phase electrical power. In an alternative embodiment, the electrical and control components may be individually connected or wired during installation at the facility to suit customer preference. The electrical and control system  70  includes an electrical system  72  having a central electrical unit  74  that receives a source of electrical power from a conventional electrical power source at facility  50 . Central electrical unit  74  includes the necessary conventional distribution and switching apparatus, such as transformers, breakers, contactors, switches, relays, overload protectors, etc. of a standard and commercially available type for operating the motors associated with compressor  44  and the fan  76 , the defrosting elements  78 , cooling device case lights  80 , the anti-sweat heaters  82  and the compressor high and low temperature switches  86  and  88 . Anti-sweat heaters  82  may be provided on any surface of the low temperature cooling device  34  or medium temperature cooling device  36  that may be subject to condensation, including, but not limited to, doors, windows, walls, panels, air-flow ducts, housings, etc. In an alternative embodiment, the compressor motor may be supplied by a separate power supply and may also be provided with a separate compressor control module including devices such as contactors, etc. for operation of the compressor motor. The compressor control module may be separately mounted or may be included as a component within the central electrical unit.  
         [0025]    Referring further to FIG. 5, the electrical and control system  70  also includes a control system  100  for controlling the operation of cooling device  32 . Control system  100  has a control module  102  that receives electrical power from central electrical unit  74 . In a particularly preferred embodiment, control module  102  includes a microprocessor having software that may be custom developed in-house or may be commercially developed according to specifications by a commercial supplier such as Danfoss Inc. of Baltimore, Md. A variety of sensors may be provided with the distributed refrigeration system including, among others, a cooling interface inlet air temperature sensor  110 , a cooling interface outlet air temperature sensor  112 , a cooling interface surface temperature sensor  114 , cooling interface refrigerant pressure sensor  116 , a simulated product temperature sensor  118 , and a cooling device air temperature sensor  120 . Sensors  110 ,  112 ,  114 ,  118  and  120  may be thermocouples, thermistors or resistance temperature devices (RTDs) and suited for use with control system  100 . The simulated product temperature sensor  118  is provided in a material having the typical mass and thermal inertia characteristics of the products intended for storage or display in cooling device  32  and may be used during either or both of initial testing operation or commercial operation to provide an indication of actual product temperature within cooling device  32 . In a particularly preferred embodiment, control module  102  receives a signal representative of temperature from one or more of sensors  110 ,  112 ,  114 ,  118  and  120  and provides an output signal to control operation of compressor  42 , fan  76  and defrosting elements  78 . Control system  100  includes a timer  104  for initiating a defrost mode of operation on a predetermined frequency (e.g. once per day) where the electric defrosting heater elements  78  are energized and compressor  42  is temporarily stopped. The duration of the defrost mode of operation is terminated by either of a signal representative of defrosted condition temperature from cooling interface surface temperature sensor  114  or on a predetermined elapsed shut-off time from timer  104  which acts as a backup device to reinitiate the cooling mode of operation (e.g. by shutting off electric defrost heaters  78  and restarting compressor  42 ) in the event of failure of sensor  114 . In an alternative embodiment, the control module software may be developed in-house and the control module may be configured to receive and send other control signals to control the operation of the distributed refrigeration system. In another alternative embodiment, the defrost mode of operation may be initiated without the use of a timer and may be based upon a signal representative of refrigerant pressure within the cooling interface. In a further alternative embodiment, the defrost mode may be controlled by any of the sensors that provide an indication of the cooling performance of the cooling interface.  
         [0026]    According to any preferred embodiment, the distributed refrigeration system provides a stand-alone cooling device with a self-contained refrigeration system that is intended to reduce installation time, ownership costs and improve retrofitting flexibility by providing a pre-assembled unit that eliminates the need for a refrigerant piping network external to the cooling device and the corresponding additional amount of refrigerant necessary in such conventional systems with refrigerant networks. The distributed refrigeration system also gains efficiency from avoidance of a receiver and by using lower condensing temperatures compared to conventional supermarket refrigeration systems. The distributed refrigeration system further minimizes the potential for future refrigerant leakage by providing factory installed piping and connections and piping leakage detection and repair is more readily addressed by the location, limitation and accessibility of the refrigerant piping. The distributed refrigerant system also provides for multiple cooling devices having different temperature applications (e.g. low temperature and medium temperature devices) to be cooled by a common secondary coolant and chiller loop.  
         [0027]    According to alternative embodiments, the distributed refrigeration system may include a medium temperature cooling device such as a refrigerator, a cold storage room, etc. of a low temperature cooling device such as a freezer case, walk-in freezer, etc. In further alternative embodiments, the cooling system may be an open storage or display device such as “reach-in” coolers that may have a fan, airflow passages or other devices for creating an “air curtain” of cooled air that creates a boundary between warmer ambient air and the cooled space in which the objects are stored and/or displayed.  
         [0028]    It is important to note that the construction and arrangement of the elements of the distributed refrigeration system provided herein are illustrative only. Although only a few exemplary embodiments of the present invention have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible in these embodiments (such as variations in features such as components, coolant compositions, heat removal sources, defrosting devices, orientation and configuration cooling interfaces, location of components and sensors of the cooling and control systems; variations in sizes, structures, shapes, dimensions and proportions of the components of the system, use of materials, colors, combinations of shapes, etc.) without materially departing from the novel teachings and advantages of the invention. For example, closed or open space refrigeration systems may be used having either horizontal or vertical access openings, and cooling interfaces may be provided in any number, size, orientation and arrangement to suit a particular refrigeration system. According to other alternative embodiments, the distributed refrigeration system may be used with any cooling device using a direct expansion refrigerant or other coolant for transferring heat from one space to be cooled to another space or source designed to receive the rejected heat and may include commercial, institutional or industrial refrigeration devices. According to further alternative embodiments, the defrosting of the cooling interface may be provided by warm air circulation, hot gas (i.e. refrigerant) circulation, or circulation of a liquid coolant. Further, it is readily apparent that variations of the distributed refrigeration system and its components and elements may be provided in a wide variety of types, shapes, sizes and performance characteristics, or provided in locations external or partially external to the refrigeration system. Accordingly, all such modifications are intended to be within the scope of the inventions.  
         [0029]    The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating configuration and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the inventions as expressed in the appended claims.