Patent Application
20150113986
The present invention is directed to an ultra-high-efficiency engine system and corresponding thermodynamic system and, in particular, to such a system that uses a common working fluid in both the power production portion and the heat pump portion of the system.
The temperature versus entropy (T vs. S) diagram of
This heat discharge out of the prior art system makes it unfeasible to consider a traditional Rankine cycle for any cryogenic power cycle, since the waste stream is at a cold temperature many hundreds of degrees below ambient. The present invention overcomes such limitations.
A thermodynamic system and method for performing work, according to an aspect of the invention, 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. The conversion device may be part of a heat pump pumping heat from one portion of the working fluid to another portion of the working fluid.
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.
A greatly simplified combined heat pump/power cycle system, according to aspects of the invention, may be used with helium, neon, or argon as a working fluid because they are very low temperature cryogenic fluids necessary for the combined heat pump/power cycle system to function properly. The other very rare and expensive cryogenic fluids, krypton and xenon, are also feasible, but not needed in most applications. Blended fluids consisting of various ratios of helium, neon, or argon may be used to accommodate the temperature range of the heat source. Organic fluids exist at temperatures slightly below ambient for various refrigeration applications of the past. A variety of low temperature synthetic fluids, many of which are yet to be developed, may be used.
A thermodynamic system and method of producing useful work, according to an aspect of the invention, includes providing a working fluid and a fluid pump for pumping the working fluid through a cycle. A thermal input is provided for supplying heat to the working fluid. An expansion device downstream of the thermal input converts motion of the working fluid to useful work. A unique heat pump, according to an embodiment of the invention, is provided and will be described in greater detail later. The heat pump pumps heat from one portion of the working fluid to another portion of the working fluid.
Commonly assigned U.S. Pat. No. 8,707,701 B2, the disclosure of which is hereby incorporated herein by reference, discloses adding a heat pump loop to a Rankine power cycle as a means of recovering the low grade waste heat resulting in a substantial increase (from 35% to 80%) in power system efficiency and greatly reduces the magnitude of the low grade waste heat. The embodiments disclosed herein use a single working fluid and eliminate the boiling and re-boiling across the “so-called” wet region of the T vs. S curve. It eliminates the need for a large compressor in the heat pump system. This provides more power production that is available for performing work.
Operation is primarily focused within the cryogenic temperature regime, such as helium, but other fluids, such as neon, argon and blends of helium, neon and argon and more exotic cryogenic fluid may be used.
These and other objects, advantages and features of this invention will become apparent upon review of the following specification in conjunction with the drawings.
Referring now to the drawings and illustrative embodiments depicted therein a thermodynamic system 10 includes a circuit 12 circulating a working fluid, a fluid pump 14 for pumping the working fluid through a cycle in circuit 12, a thermal input 16 for supplying heat to the working fluid and an expansion device 18 downstream of thermal input 16 for converting at least the heat of the working fluid to useful work (
The working fluid in circuit 12 includes a noble gas, such as helium, and has a portion of the working fluid in circuit 12 operating in a cryogenic temperature region. Operation of system 10 with helium as the working fluid is illustrated beginning at
Operation of system 10 is as follows. The cycle begins with the helium reservoir 34 at the extreme bottom of the cycle. The liquid is then pumped to a pressure above the high-operating pressure of the power system (for example, 200 atmospheres) and adds heat of compression to the working fluid. The stream then enters the first portion 30 of heat pump exchanger 29 in a direction opposite the main system flow with respect to heat transfer. The working fluid gives up the heat of compression and then enters a conversion device, such as a J-T valve 22 or, alternatively, a small liquid turbine, which drops the pressure down to the operating pressure (such as 100 atmospheres). Flow then enters the low pressure side of the heat pump heat exchanger 32 to receive heat from heat exchanger 30 and deposit the heat of compression and waste heat back into the system high pressure flow. From there, the high pressure stream (which begins to change from a liquid to a vapor state) enters the second portion 26 of main heat exchanger 20 to exchange heat with first portion 24 receiving the low pressure stream leaving the main power turbine 18. When the high pressure stream leaves the main heat exchanger 26, its temperature is in the low temperature range of negative 200 degrees F. to negative 110 degrees F., substantially below ambient. This very cold stream now enters thermal input 16 which may be a heat exchanger system embedded in one of the earth's near-ambient temperature sources, such as the air, water, soil, or a geo-thermal well. Likewise, this heat exchanger system could be in the waste heat stream of a fossil fuel or nuclear-fired power plant, or in various waste streams of diesel or internal combustion engines. The temperature of the high pressure stream as it exits the thermal input 16 of the heat input heat exchanger could vary from near ambient to 800 degrees F. or 900 degrees F. depending on the exact application and system design. A very large temperature gradient exists across the main heat input heat exchanger.
The high pressure stream now enters the main power turbine or turbine power system 18 to generate power or produce other useful work. Power production results in a substantial reduction in both stream temperature and pressure. From turbine exit, the stream enters the first portion 24 of main heat exchanger 20 and then returns to the helium reservoir 34 primarily as a liquid. The system heat exchangers are designed to prevent boil-off in the steady state. However, in transient upset, or normal dewar boil-off, a small compressor 36, as shown on the lower right, provides sufficient refrigeration to return boil-off gas to liquid.
A diagram 140 illustrates operation of system 10 using neon as a working fluid in circuit 12 (
System 10 may achieve up to 80% efficiency and is capable of operating on low temperature heat source. As such, thermal input 16 may receive earth surface sensible heat, (i) geothermal heat from a geothermal well, (ii) latent heat of surface water, (iii) sensible heat of surface water, or (iv) heat from ambient air. However, heat input 16 may be used as a power-producing bottoming system for an existing or new fossil-fuel-fired power plant or for an existing or new nuclear power plant. Heat input 16 may be used as a power-producing bottoming-cycle for an existing or new diesel engine and an existing or new internal combustion engine. Other applications will be apparent to the skilled artisan and as set forth in my earlier U.S. Pat. No. 8,707,701 B2, issued Apr. 29, 2014, the disclosure of which is hereby incorporated herein by reference.
A thermodynamic system 110 that operates without a heat pump, per se, includes a working fluid in a circuit 112 including a thermal input 116 and an expansion device, such as a gaseous power turbine 118 (
Thus, it can be seen that the invention as illustrated in the embodiments herein reduces the amount of boiling and re-boiling to as close to zero as possible and does so in a manner that reduces the number of components in the overall system. Also, the system uses one working fluid, not two. As many components as possible are eliminated.
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.
This application claims priority from U.S. provisional patent application Ser. No. 61/895,445, filed on Oct. 25, 2013, the disclosure of which is hereby incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61895445 | Oct 2013 | US |
