Abstract:
A thermodynamic system and method for performing work includes a working fluid and a fluid pump for pumping the working fluid through a cycle. A thermal input supplies heat to the working fluid. An expansion device downstream of the thermal input converts at least the heat of the working fluid to useful work. A heat exchanger downstream of the expansion device has a first portion to transfer heat from downstream said expansion device to a second portion at or upstream of said thermal input. A conversion device expands the working fluid with constant enthalpy from a higher to a lower pressure.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 14/522,117, filed Oct. 23, 2014, which claims priority from U.S. provisional application Ser. No. 61/895,445, filed on Oct. 25, 2013, the disclosures of which are hereby incorporated herein by reference in their entireties. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention is directed to an ultra-high-efficiency engine system and corresponding thermodynamic system and, in particular, to such a system that operates in a single loop closed cycle. 
         [0003]    Steam is used in typical electric generating plants worldwide. The low pressure return path crosses the wet region of the temperature versus entropy (T vs. S) plot to complete the power cycle, which results in substantial heat loss to the earth environment, and a power plant efficiency only in the 30% range. Both the OTTO (internal combustion) cycle and the diesel engine cycle employ gaseous compressions which consume much power. Both the existing low-efficiency (in the 30% range) cycles map out extensively along the waste heat “x”-axis of the T vs. S plot. 
         [0004]    In my U.S. Pat. No. 8,707,701 B2, entitled ULTRA-HIGH-EFFICIENCY ENGINES AND CORRESPONDING THERMODYNAMIC SYSTEM, issued Apr. 29, 2014, are shown numerous power systems in which a heat pump loop is added to a conventional power system to increase the efficiency of the combined cycle power system. The enthalpy of the bottom of the heat pump cancels out the enthalpy of the opposite flowing bottom of the power cycle. Likewise, the compressor of the heat pump cycle uses up a like amount of enthalpy from the vertical part of the power cycle. The result is an ultra-high-efficiency system using two closed cycles, one dominant cycle, and a minor cycle. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention provides a new cycle is that it does not significantly cross the “so called wet region.” Use of heat-exchanger between low-pressure power turbine exiting heat, and incoming high-pressure input heat, resulting in efficiency system well into the 90% range, with miscellaneous heat leaks accounting for a 10% balance. 
         [0006]    A single dominate loop thermodynamic system and method for performing work, according to an aspect of the invention, includes a working fluid and a fluid pump, such as a liquid pump for pumping the working fluid through a cycle. A thermal input supplies heat to the working fluid. An expansion device downstream of the thermal input converts at least the heat of the working fluid to useful work. A heat exchanger downstream of the expansion device has a first portion to transfer heat from downstream said expansion device to a second portion at or upstream of said thermal input. A conversion device converts the fluid back to a liquid. The conversion device expands the working fluid with constant enthalpy from a higher to a lower pressure. 
         [0007]    The invention is directed to a thermodynamic system and method that may find application in the direct extraction of power from earth surface sensible heat, from the heat of geothermal wells, from the latent and sensible heats of surface water and from the heat in ambient air. No other heat or fuel source is required. However, embodiments of the invention may also find application as a power-producing bottoming system for existing and new fossil-fuel-fired and nuclear power plants and for such engines as Diesel and internal combustion. 
         [0008]    These and other objects, advantages, purposes, and features of this invention will become apparent upon review of the following specification in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a block diagram of a closed cycle thermodynamic system according to an embodiment of the invention; 
           [0010]      FIG. 2  is a temperature vs. entropy (T vs. S) diagram of the embodiment in  FIG. 1 ; 
           [0011]      FIG. 3  is the same view as  FIG. 2  of a system using Nitrogen as the working fluid; 
           [0012]      FIG. 4  is a bar chart illustrating temperature region in which the embodiment shown in  FIG. 1  operates; 
           [0013]      FIG. 5  is the same view as  FIG. 1  of another embodiment of the invention; 
           [0014]      FIG. 6  is the T vs. S diagram of the embodiment in  FIG. 5 ; 
           [0015]      FIG. 7 a    is the power portion of a T vs. S diagram of a system using helium as the working fluid; 
           [0016]      FIG. 7 b    is the pressure portion of the T vs. S diagram in  FIG. 7   a;    
           [0017]      FIG. 8 a    is the power portion of a T vs. S diagram of a system using neon as the working fluid at high temperature; 
           [0018]      FIG. 8 b    is the compression portion of the T vs. S diagram in  FIG. 8   a;    
           [0019]      FIG. 9  is the power portion of the T vs. S diagram of a system using helium as a working fluid; 
           [0020]      FIG. 10  is the power portion of the T vs. S diagram of a system using argon as a working fluid at high temperatures; 
           [0021]      FIG. 11  is a T vs. S. diagram of carbon dioxide; 
           [0022]      FIG. 12  is a block diagram of a high pressure air system according to an embodiment of the invention; and 
           [0023]      FIG. 13  is a block diagram of a system according to an embodiment of the invention that produces power as well as cool air. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    Referring now to the drawings and the illustrative embodiments depicted therein, a thermodynamic system  10  includes a liquid tank or cryogenic Dewar  11  that is maintained at some nominal pressure near absolute zero or slightly above. A liquid pump  14  elevates a wording fluid  12  in the liquid state to the desired operating pressure. The fluid is heated in a heat absorbing coil  22  of a heat exchanger  20  by the returning low pressure stream passing through a heat transfer coil  24  after it exits an expansion device such as a power turbine  18 . The high pressure stream enters a heat source  16  which heats the working fluid to the top temperature of the cycle. The high pressure and the high temperature working fluid enters the power producing gas turbine  18 . The working fluid as a low pressure stream exits turbine  18  and transfers its heat to the high pressure stream via heat exchanger  20 . The low pressure stream enters a conversion device  26  in the form of a J-T valve, which takes the working fluid from the bottom of low-pressure side  24  of heat-exchanger  20  along a constant enthalpy line, to the bottom of the working fluid tank  11  in the liquid dominated (90%) bottom side of the tank. For some applications, the conversion device maybe a liquid turbine, a gas turbine, or a J-T valve turbine combination. Because the working fluid in liquid form is at the bottom of tank  11 , the J-T valve discharges to the bottom portion of tank  11 . The closed thermodynamic cycle begins anew at the intake of liquid pump  14 . 
         [0025]    The working fluid (m) in tank  11  in the illustrative embodiment is approximately 90% (0.9 m) liquid and 10% (0.1 m) gas. A boiled-off gas compressor  28  compresses the gas from tank  11  to a higher press gas state, and injects the gas output of compressor  28  to top system pressure and merges the approximate 10% gas working fluid with the 90% stream now a gas at the junction between heat absorbing coil  22  and heat source  16 . 
         [0026]    System  10  may be started by starting the high pressure flow by applying the heat source  16  which will start the turbine  18 . After the turbine, the flow will heat the low pressure side  24  of the heat exchanger  20 , which will then heat the high temperature side at  22 . 
         [0027]    Referring to  FIG. 2 , the thermodynamic cycle of system  10  has most of the characteristics of a conventional Rankine cycle, except that the return path goes to the left of the wet region instead of to the right, or through the wet region as is the case with a conventional steam cycle. For steam, the gaseous region above the wet region is very small compared to the wet region, and there is no room to take the return path below the steam turbines. Working fluid  12  has a very substantial gaseous regions in comparison to the wet regions. Working fluid  12  is illustrated in  FIGS. 1 and 2  as argon. 
         [0028]    The top temperature of system  10  is illustrated at 300 degrees K, which corresponds to earth ambient temperature. Hence, the very low temperatures of the cycle operates in the cryogenic regime.  FIG. 4  illustrates the cryogenic regime compared to the steam cycle regime. The cryogenic regime is about one-half the temperature range of the steam cycle regime. To date the cryogenic cycle regime has not been used for power generation. Such a cycle can be fueled with one of many ambient temperature sources of heat. This is very significant since global heat passing into one of these new cryogenic temperature engines potentially reduces global heating by producing motive or electric power. This ambient heat can be captured by using a piping network buried in the ground, much like that currently used to augment furnaces in winter. Flowing water in a creek or river with a properly designed heat exchanger is another way of gathering in this ambient heat. 
         [0029]    This type of cryogenic cycle can also operate as a bottoming cycle operating on the discharge stream from a large coal fired, or nuclear fueled power plant, or the cooling fluid discharge of a Diesel engine, or internal combustion engine. Power plants and present day Diesel and internal combustion engines are somewhere between 30% and 40% efficient. The present invention provides a technique for capturing most of the 60% to 70% of the fuel that goes to heating the atmosphere. 
         [0030]      FIG. 3  shows that nitrogen is a potential candidate for use with system  10 .  FIGS. 5 and 6  illustrate is a lower pressure version of an argon cycle. The argon cycle of  FIG. 1  is shown with a top pressure of approximately 1000 atm.  FIGS. 5 and 6  illustrate a lower pressure argon system  110  that reaches approximately 200 atm. A small bleed flow through a bleed turbine  30  from the low pressure return heat transfer coil  24  is taken and re-injected downstream to tank  111  at an appropriate pressure. 
         [0031]      FIGS. 7 a  and 7 b    show the T vs. S diagram for helium as a working fluid at temperatures below 300 degrees K. Helium is viable for these systems since it operates at reasonable low pressures. However, helium is in short supply and for high flow applications, neon may be a preferable working fluid. Neon is shown in  FIGS. 8 a  and 8 b   . Neon also operates at low enough pressures to be viable. 
         [0032]      FIG. 9  shows that helium can be used as a working fluid all the way up to at least 2700 degrees Rankine (3160 Fahrenheit). Since helium is a monatomic fluid, it will not disassociate at these high temperatures, which enables it to be used for most engine processes.  FIG. 10  shows that other noble (monatomic) fluids such as argon can also operate well above cryogenic temperatures and can be potentially used in combustion and nuclear power cycles. 
         [0033]      FIG. 11  shows the wet region of carbon dioxide. Carbon dioxide, or blended with other fluids such as ammonia, might function well with the systems disclosed herein. Hot carbon dioxide is one of the power producing fluids in existing engines and power plants. It is typically discharged to atmosphere and is a greenhouse gas. Thus, its use in an ultra-high-efficiency thermodynamic system will have the added benefit of turning a harmful byproduct into a useful ingredient. 
         [0034]    The present invention may also be embodied in high pressure ratio jet engines and air conditioners that produce electric power instead of consuming it.  FIG. 12  shows the basic concept of a high pressure ratio jet engine  200  using a system process  201 . A very low temperature cryogenic coil  202  is used to cool incoming air to liquid air. The liquid air is then pumped to a very high pressure with a liquid pump  203  and then heated by a heater  204 , using output power of system process  201 , back to a gas. In some cases, all or part of the generated power is used to perform other functions on the airplane. 
         [0035]      FIG. 13  shows an air conditioner  300 . A battery or generator driven fan  301  brings hot outside air into a duct or chamber  302  cooled by a very low temperature cryogenic coil  303 . The new cycle recharges the battery and produces additional power from the heat (enthalpy) extracted from the air by the cryogenic temperature variant of this new cycle. This version of an air conditioner produces power instead of consuming it, thus contributing greatly to betterment of the environment. 
         [0036]    The present invention is embodied in a system which begins at the saturated liquid curve of the T vs. S graph and ends at the same point, thus not substantially rejecting heat other than through miscellaneous heat leaks. Thus, there are a number of “closed-thermodynamic-cycle gas-turbines” on the left side of most T vs. S charts that function with no rejection of heat, except small parasitic insulation heat leaks all are capable of operating with efficiencies well into the 90% bracket. 
         [0037]    Thus, it is seen that the present invention provides a totally new cycle/engine, embodied in a single closed thermodynamic cycle of a liquid pump, a heat exchanger, a heat source, and a gas turbine, forming a closed cycle power system based exclusively left of the wet region on a T vs. S plot has been defined. Cryogenic fluids such as helium, neon, argon, nitrogen, and air make it feasible to extract motive power and electricity from ambient heat sources such as ground, water, and air. This cycle is also capable of functioning as a bottoming cycle for steam plants, Diesel trucks, and automobiles. This new cycle is capable of functioning alone to power electric generating plants, trucks, and automobiles, using such ambient based fluids as carbon dioxide. This researcher believes that the Diesel and internal combustion engines, and the steam power plant, all developed in the eighteen hundreds, need to be retired because they are nominally 33% efficient, and dump the nominal 67% balance as heat to the atmosphere. He also believes that the new cycle would be very difficult to integrate into these old systems because there are numerous interface conditions that must be satisfied. This new system could potentially be better engineered as a standalone. 
         [0038]    While the foregoing description describes several embodiments of the present invention, it will be understood by those skilled in the art that variations and modifications to these embodiments may be made without departing from the spirit and scope of the invention, as defined in the claims below. The present invention encompasses all combinations of various embodiments or aspects of the invention described herein. It is understood that any and all embodiments of the present invention may be taken in conjunction with any other embodiment to describe additional embodiments of the present invention. Furthermore, any elements of an embodiment may be combined with any and all other elements of any of the embodiments to describe additional embodiments.