Abstract:
An electrical generator for use in conjunction with a heat exchange system having an evaporator and a condenser is presented. The electrical generator comprises a control circuit, a moderator and a working spool. The moderator comprises a moderator cylinder having a moderator chamber and three moderator ports in fluid communication with the moderator chamber. The three moderator ports are respectively in fluid communication with the evaporator, the condenser and the working spool. The moderator and working spool each comprise a coil surrounding at least a portion of a cylinder having a piston slidably disposed therein. The working spool coil is configured for generating current upon movement of the working spool piston. Movement of the working spool piston is achieved through the selective admission of the working fluid to the working spool as controlled by the moderator and the control circuit.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to generation of electricity. More specifically, the invention relates to a generator that converts energy supplied by expanding gases and increased pressure into electrical energy. 
         [0002]    In satisfying energy needs for the future, increasing attention is being paid to smaller, localized power sources distributed through the power consuming community as an alternative to large centralized power plants. Large centralized power plants generally require large electrical distribution networks with long power transmission lines to provide the power produced to customers. Such large power transmission losses are typically associated with such distribution networks. 
         [0003]    The systems used in large centralized power plants often include rotating devices, such as steam or gas turbines or Pelton wheels. However, when scaled down for use in smaller power generation systems, high rotation speeds must be achieved to maintain acceptable system efficiencies. Such high rotations speeds often cannot be achieved without uncommon materials and/or precision machining, each of which results in increased system cost. 
         [0004]    Accordingly, a localized system of producing electrical energy that may operate with acceptable efficiencies without costly manufacturing processes is desirable. 
         [0005]    Greater attention is being paid to renewable energy sources, such as solar power, as an environmentally favorable alternative to fossil fuels. It is known in the art to capture solar energy and transform it into electrical power using photovoltaic systems However, photovoltaic systems traditionally have low efficiencies that often undermine the economic viability of such systems. Accordingly, energy production systems that utilize solar energy to produce electrical power while maintaining acceptable efficiencies are desirable. 
         [0006]    Moreover, it is desirable for an energy production system to utilize waste heat from other processes to produce electrical energy. The use of waste heat to generate electrical power that may be returned to an underlying process may increase the efficiency of the underlying process, require less energy input, and accordingly, less cost to operate. 
         [0007]    Power generation with mechanical devices that utilize a reciprocating piston are known, as are systems that utilize a second piston in a spool (e.g., a valve) to moderate a working piston. However, such systems are typically arranged in a manner that the electrical power that is produced is input into a rotating shaft that may drive an electrical generation device. As discussed above, rotating devices often require high rotating speeds and/or precision machining to achieve acceptable efficiencies 
         [0008]    Additionally, electrical generation by a magnetized piston reciprocating through a spool is also known. However, the force supplied to move the magnetized piston through the spool typically produced through mechanical means. 
         [0009]    It is accordingly desirable to provide a power generation system that utilizes heat and its corresponding effect on fluid to cause a magnetized piston to reciprocate through a coil in order to generate electrical power. The heat utilized in the power generation system may be dedicated heat, waste heat, or may be supplied by solar power. 
       SUMMARY OF THE INVENTION 
       [0010]    Aspects of the invention may include systems and methods for generating electricity with an electronically moderated expansion electrical generator. An electrical generator according to a particular aspect of the invention may be used in conjunction with a heat exchange system having an evaporator and a condenser adapted for operating on a working fluid. The evaporator may have an evaporator intake port for receiving working fluid in a liquid state and an evaporator outflow port for transmission of working fluid in a gaseous state, and the condenser may have a condenser intake port for receiving working fluid in a gaseous state and a condenser outflow port for transmission of fluid in a liquid state. The electrical generator comprises a control circuit, a moderator and a working spool. The control circuit comprises an electrical storage module and a timing module. The moderator comprises a moderator cylinder having a moderator chamber and first, second and third moderator ports in fluid communication with the moderator chamber. The first moderator port is also in fluid communication with the evaporator outflow port and the third moderator port is also in fluid communication with the condenser intake port. The moderator further comprises a moderator coil surrounding at least a portion of the moderator cylinder. The moderator coil is in electrical communication with the control circuit. A moderator piston comprising a magnetic body is slidably disposed in the moderator chamber. The moderator piston is capable of translating between a first position wherein the first moderator port and the second moderator port are in fluid communication and a second position wherein the third moderator port and the second moderator port are in fluid communication. The working spool comprises a working spool cylinder having a working spool chamber and first, second and third working spool ports. The first working spool port is in fluid communication with the second moderator port, the second working spool port is in fluid communication with the condenser outflow port, and the third working spool port is in fluid communication with the evaporator inlet. A working spool coil surrounds at least a portion of the working spool cylinder. The working spool coil is in electrical communication with the control circuit. A working spool piston comprising a magnetic body is slidably disposed in the working spool chamber. The working spool piston divides the working spool chamber into a condenser side volume in fluid communication with the first working spool port and an evaporator side volume in fluid communication with the second working spool port. The working spool piston is capable of translating between a first position in which the second working spool port is in fluid communication with the condenser side volume and a second position wherein the second working spool port is closed. The first working spool port is configured and positioned so that when pressurized fluid is received through the first port, the pressurized fluid causes the working spool piston to translate from the first position to the second position. 
         [0011]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. The accompanying drawings constitute a part of the specification, illustrate certain embodiments of the invention and, together with the detailed description, serve to explain the principles of the invention. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0012]    In order to assist in the understanding of the invention, reference will now be made to the appended drawings, in which like reference characters refer to like elements. The drawings are exemplary only, and should not be construed as limiting the invention. 
           [0013]      FIG. 1  depicts a block diagram of an electrically moderated expansion electrical generator in accordance with some embodiments of the present invention. 
           [0014]      FIG. 2  depicts generalized schematic diagram of an electrically moderated expansion electrical generator in accordance with some embodiments of the present invention. 
           [0015]      FIG. 3  depicts an electrically moderated expansion electrical generator according to some embodiments of the invention. 
           [0016]      FIG. 4  depicts the electrical circuit of an electrically moderated expansion electrical generator according to some embodiments of the invention. 
           [0017]      FIG. 5  depicts an electrically moderated expansion electrical generator at time T 0  during a cycle according to some embodiments of the invention. 
           [0018]      FIG. 6  depicts an electrically moderated expansion electrical generator at time T 1  during a cycle according to some embodiments of the invention. 
           [0019]      FIG. 7  depicts an electrically moderated expansion electrical generator at time T 2  during a cycle according to some embodiments of the invention. 
           [0020]      FIG. 8  depicts an electrically moderated expansion electrical generator at time T 3  during a cycle according to some embodiments of the invention. 
           [0021]      FIG. 9  depicts an electrically moderated expansion electrical generator at time T 4  during a cycle according to some embodiments of the invention. 
           [0022]      FIG. 10  depicts an electrically moderated expansion electrical generator at time T 5  during a cycle according to some embodiments of the invention. 
           [0023]      FIG. 11  depicts an electrically moderated expansion electrical generator at time T 6  during a cycle according to some embodiments of the invention. 
           [0024]      FIG. 12  depicts an electrically moderated expansion electrical generator at time T 7  during a cycle according to some embodiments of the invention. 
           [0025]      FIG. 13  depicts an electrically moderated expansion electrical generator at time T 8  during a cycle according to some embodiments of the invention. 
           [0026]      FIG. 14  depicts an electrically moderated expansion electrical generator at time T 9  during a cycle according to some embodiments of the invention. 
           [0027]      FIG. 15  depicts an electrically moderated expansion electrical generator at time T 10  during a cycle according to some embodiments of the invention. 
           [0028]      FIG. 16  depicts an electrically moderated expansion electrical generator at time T 11  during a cycle according to some embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0029]    Reference will now be made in detail to embodiments of the invention, examples of which are illustrated in the accompanying drawings 
         [0030]    With reference to  FIG. 1 , a power generation system  10  in accordance with some embodiments of the present invention will now be discussed. The power generation system  10  may generally comprise a working spool  100 , a moderating spool  200 , an evaporator  300 , a condenser  400 , and a control circuit  600 . The working spool  100  comprises a piston that may be magnetized or may have magnets attached thereto disposed in a cylinder, and a coil surrounding the cylinder. The working spool  100  is fluidically connected to the moderating spool  200 , the evaporator  300 , and the condenser  400 . Such connections may be via tubing  500 , which may be any tubing, piping, or conduit sufficient to cause communication of fluids in both gaseous and liquid phases. 
         [0031]    Similar to the working spool  100 , the moderating spool  200  comprises a piston that may be magnetized or may have magnets attached thereto disposed in a cylinder, and a coil surrounding the cylinder. The moderating spool is also fluidically connected to the working spool  100 , the evaporator  300 , and the condenser  400  via tubing  500 . 
         [0032]    The evaporator  300  may be any body that contains a fluid that, when heat is applied, causes the fluid to evaporate from its liquid state to a gaseous state. The evaporator  300  is exposed to a heat source (not shown) and may be connected to the working spool  100  and moderating spool  200  via the tubing  500 . 
         [0033]    In contrast to the evaporator  300 , the condenser  400  is any body that causes a fluid in a gaseous state to cool and return to its liquid state. The condenser  400  may include a cooling device, such as but not limited to, a fan. The condenser  400  is also connected to the working spool  100  and moderating spool  200 . 
         [0034]    The control circuit  600  controls the interactions and the timing of the working spool  100  and the moderating spool  200 , and is electrically connected to the working spool  100  and the moderating spool  200 . The control circuit  600  may include various electronic components, including a power source and/or power storage device. 
         [0035]    With reference to  FIGS. 1 and 2 , generalized operation of the power generation system  10  will now be discussed. Heat may be applied to the evaporator  300 , causing fluid therein to evaporate from its liquid state to a gaseous state. Such evaporation provides pressure through the open moderating spool  200  onto one surface of the a piston  10  in the working spool  100 . A small amount of electrical energy may be supplied from the control circuit  600  to the working spool coil  120  in order to prevent the working spool piston  110  from moving under the pressure. Once sufficient pressure has built up, the electrical current from the control circuit  600  is ceased, and the working spool piston  110  is subject to the increased pressure from the evaporator  300 . 
         [0036]    The increased pressure may cause the magnetized working spool piston  10  to slide in its cylinder and accordingly through the working spool coil  120 . As the working spool piston  110  slides through the working spool coil  120 , electrical energy is created, and may be captured by the control circuit  600  and stored in a power storage device (e.g., battery). Additionally, as the working spool piston  110  slides in its cylinder, it presents additional volume for the gaseous fluid to expand to. In order to maintain increased pressure, condensate from the condenser  400  may be fed to the evaporator  300  via the working spool  100 . Once the working spool piston  110  has completed its stroke, it obstructs the flow of condensate from the condenser  400  to the evaporator  300 . This prevents additional fluid pressure from being generated by the evaporator  300 . 
         [0037]    The moderating spool  200  may now be activated by the control circuit  600 . The control circuit  600  supplies electrical power to the moderating spool  200 , causing the magnetized moderating spool piston  210  to slide within its bore. When the moderating spool piston  210  has completed its travel, it opens a pathway from the working spool  100  to the condenser  400 . The gases trapped in the working spool  100  may therefore travel into the condenser  400 . The gases may be condensed to their liquid phase for later use. 
         [0038]    The control circuit  600  now supplies electrical power to the working spool  100 , in order to cause the working spool piston  100  to move within it bore and return to its starting position. By applying a current through the working spool coil  120 , the working spool piston  110  is caused to move. As the working spool piston  110  moves within its bore, it forces any additional gases out of the working spool cylinder and to the condenser  400 . During this motion, the working spool piston  110  may also draw condensate from the condenser  400  that is supplied to the evaporator  300 . Once the working spool piston  110  is back in its original position, the moderating spool piston  210  returns to its original position, either by utilizing electric power from the control circuit  600 , or by being forced back into its original position by the expanding gases of the evaporator  300 . Once the moderating piston is back to its original position, the system  10  is recharged and ready to repeat the process. 
         [0039]    The system described above is a closed loop system in which the working fluid is repeatedly caused to change phase through the use of an evaporator and a condenser. It will be understood, however, that some embodiments of the invention make use of an open system in which the working fluid is continually exhausted and replenished. In such embodiments, the evaporator may be replaced by any fluid source providing fluid at high pressure (and, in many cases, high temperature) and the condenser may be replaced by any exhaust environment at a lower pressure than that of the fluid source. Typically in such embodiments working fluid is not recaptured. One example of such a system is one in which the working fluid is the exhaust from an internal combustion engine and the exhaust environment is the atmosphere. 
         [0040]    With reference to  FIG. 3 , power generation system in accordance with some embodiments of the present invention will now be discussed in more detail. A working spool  100  comprises a cylinder divided into two sides, a working evaporator side  130  and a working condenser side  140 . These sides are separated by a working spool piston  110 . The working spool piston  110  may be magnetized or may have magnets attached thereto. A working spool coil  120  surrounds at least a portion of the working spool cylinder. The working spool cylinder comprises a first port, a second port, and a third port. The first port provides communication between the working evaporator side  130  and the moderating spool  200 . The second port provides communication between the working condenser side  140  and the condenser  400 . The third port provides communication between the working condenser side  140  and the evaporator  300 . 
         [0041]    Similarly, the moderating spool  200  comprises a cylinder divided into two sides, a moderating evaporator side  230  and a moderating condenser side  240 . These sides are separated by moderating spool piston  210 . The moderating spool piston  210  may be magnetized or may have magnets attached thereto. A moderating spool coil  220  surrounds at least a portion of the moderating spool cylinder. The moderating spool cylinder may comprise a first port, a second port, and a third port. The first port provides communication between the moderating evaporator side  230  of the moderating spool and the evaporator  300 . The second port provides communication between the moderating evaporating side  230  of the moderating spool and the working evaporator side  130  of the working spool, via the working spool&#39;s first port. The third port provides communication between the moderating condenser side  240  of the moderating spool and the condenser  400 . 
         [0042]    Tubing  500  may connect the working condenser side  140  to the condenser  400 . Tubing  500  may connect the working condenser side  140  to the evaporator  300 . The tubing  500  from the condenser  400  to the working condenser side  140  and the tubing  500  from the working condenser side  140  to the evaporator  300  may be arranged such that there may be fluidic communication from the condenser  400  to the evaporator  300  via the working condenser side  140 . This fluidic communication may be prevented when the working spool piston  110  slides in the working spool cylinder into the working condenser side  140 . Alternatively, tubing  500  from the condenser  400  may connect directly to the evaporator  300 . 
         [0043]    The evaporator  300  is connected to the moderating spool  200  via additional tubing  500 . The moderating spool  200  is connected to the working spool  100  and the condenser  400  via additional tubing  500 . 
         [0044]    As can be seen from  FIG. 3 , check valves  520 ,  530  may be used to prevent fluids from passing through the tubing in an undesirable direction. A first check valve  520  prevents fluid from traveling from the working spool  100  to the condenser  400 , while a second check valve  530  prevents fluid from traveling from the evaporator to compression volume  140  of the working spool  100 . 
         [0045]    The electrical circuit  600  is used to regulate the power generation system, and may be used to store or transfer generated electrical power. The electrical circuit  600  is electrically connected to the working spool solenoid  120  and the moderating spool solenoid  220 . In this manner, the electrical circuit can provide electricity to, and receive generated electricity from, the working spool solenoid  120  and/or the moderating spool solenoid  220 . The specific orientation and components selected for the electrical circuit  600  may be any that allow the electrical circuit to control the working spool  100  and the moderating spool  200 , and selectively provide electricity to, and receive electricity from, the working spool  100  and the moderating spool  200 . 
         [0046]    With reference to  FIG. 4 , the electrical circuit  600  generally comprises a power storage device (e.g., a battery)  620 , a diode  630 , a first and second resistor  640 ,  670 , a capacitor  650 , and a transistor  660 . These components are connected via electrical wire  610  in such a manner so as to provide the functionality discussed above. 
         [0047]    With reference to  FIGS. 4-16 , operation of a system in accordance with some embodiments of the present invention will now be discussed.  FIG. 5  depicts an electrically moderated expansion electrical generator at time T 0 . At T 0  the working piston  110  may be disposed in the working spool  100  such that the working evaporator side  130  has a minimal volume while the working condenser side  140  has a maximum volume. In other words, the working piston  110  is positioned at one end of its stroke. At T 0 , the moderating piston  210  may be disposed in the moderating spool  200  such that the moderating evaporator side  230  has a maximum volume while the moderating condenser side  240  has a minimal volume. At T 0  fluid in its liquid phase flows through tubing  500  from the condenser  400 , through the check valve  520 , through the working condenser side  140 , and to the evaporator  300 . 
         [0048]    As shown in  FIG. 6 , at time T 1  heat is applied to the evaporator  300 , causing the liquid in the evaporator  300  to boil and release and become pressurized gas. With reference to  FIG. 7 , at time T 2  heat may be continually applied to the evaporator  300  and the pressurized gas may fill the tubing  500  leading from the evaporator  300  to the moderating spool  200 . 
         [0049]    At time T 3  and as illustrated in  FIG. 8 , while heat is continually applied to the evaporator  300 , the pressurized gas enters and fills both the tubing  500  leading from the evaporator  300  to the moderating spool  200  and the moderating expansion volume  230  of the moderating spool  200 . 
         [0050]    As shown in  FIG. 9  at time T 4  the pressurized gas flows to the working evaporator side  130  via the tubing  500  and the moderating evaporator side  230 . In order to keep the pressure elevated and constant, condensate may be provided to the evaporator  300  from the condenser  400 . As shown in  FIG. 10  at time T 5  heat is applied to the evaporator  300 , and the pressurized gas fills the tubing  500  leading from the evaporator  300  to the moderating spool  200 , the moderating evaporator side  230 , the tubing  500  leading from the moderating spool  200  to the working spool  100 , and the available portion of the working evaporator side  130 . At this time, a small current may be applied from the electrical circuit  600  to the working spool coil  120  in order to resist initial movement of the working spool piston  110 . 
         [0051]    At time T 6  and with reference to  FIG. 11 , increased fluid pressure in the closed system resulting from the increased heating of the fluid in the evaporator  300  may overcome the resisting force of the current applied by the working spool coil  120  to the working spool piston  110 , such that the working spool piston  110  begins to move in a direction that results in increased volume of the working condenser side  130 . As the working piston  110  moves through the working spool coil  120 , it generates a current in the working spool coil  120  that may be applied to the electrical circuit  600 . At this point, the generated current may not yet overcome the Zener diode in the electrical circuit  600 , and accordingly produced electricity may be prevented from being introduced to the full electrical circuit  600 . 
         [0052]    As shown in  FIG. 12  at time T 7  the working spool piston  110  continues to move in its bore away from the pressurized fluid and through the working coil  120 , thereby creating a current in the working coil that may be applied to the electrical circuit  600 . Again, the generated current may not yet overcome the Zener diode in the electrical circuit  600 . 
         [0053]      FIG. 13  illustrates the system at time T 8 . The working piston  110  is continuing its travel through its cylinder and through the working coil  120 . At time T 8 , the current generated in the working coil  120  may overcome the Zener diode and may flow through the diode  630  and may charge the power storage device  620  (e.g., battery). The generated current may also begin to charge the capacitor  650  in the electrical circuit  600 . 
         [0054]    At time T 9  and with reference to  FIG. 14 , the capacitor  650  that was charged by the electric current generated by the working coil  120  discharges, and a command current flows through the transistor  660  and to the moderating coil  220 . As the command current flows through the moderating coil  220 , a force is exerted on the moderating piston  210 , causing the moderating piston  210  to move in its bore in a manner to reduce the volume in the moderating condenser side  230 . In doing so, the moderating spool piston  210  blocks the tubing connecting the moderating spool  200  to the working spool  100 . This prevents additional gas pressure from being provided to the working spool  100 . 
         [0055]    As shown in  FIG. 15 , at time T 10  the capacitor  650  discharges and the command current flows through the transistor  660  and to the moderating spool coil  220 . As the command current flows through the moderating spool coil  220 , a force may be applied to the moderating piston  210 , such that the moderating piston  210  moves in its bore in a manner to reduce the volume of the moderating evaporator side  230 . When the moderating piston  210  has moved toward the moderating evaporator side  230  a sufficient amount, fluidic communication exists between the working evaporator side  130  and the moderating spool condenser side  240 ; communication that was previously blocked by the moderating piston  210 . By opening up this communication, the addition of pressurized gas from the evaporator  300  to the working spool  100  is prevented. The pressurized gas in the working spool  100  may be released to the condenser  400  via the moderating condenser side  240  and the tubing  500 . The pressure in the working evaporator side  130  may now be lower, potentially at or near ambient atmospheric pressure. 
         [0056]    As shown in  FIG. 16 , at time T 11 , a command current is applied to the working coil  120 , thereby causing the working piston  110  to slide within its bore in a manner to reduce the volume of the working spool expansion volume  120 . Such movement may push remaining gases to the condenser  400  via the moderating condenser side  240  and the tubing  500 , and may cause condensate from the condenser  400  to be drawn into the working condenser side  140  for use in the next cycle. 
         [0057]    Finally, a command current is applied to the moderating coil  220 , causing the moderating piston  210  to move in a manner to reduce the volume of the moderating condenser side  240 , and accordingly block fluidic communication between the moderating condenser side  240  and the working evaporator side  130 . The system is now reset and ready to repeat the cycle. 
         [0058]    The above description relates to the operation of a closed-loop system. It will be understood that a similar method may be used to operate an open system in which the working fluid is provided continuously from a fluid source at a particular pressure and temperature and is exhausted to an exhaust environment at a pressure lower than the fluid source pressure. 
         [0059]    It will be apparent to those skilled in the art that various modifications and variations can be made in the method, manufacture, configuration, and/or use of the present invention without departing from the scope or spirit of the invention.