Patent Application
20110138800
The present invention generally relates to energy conversion, and more specifically, to a heat conversion device and system configured for generating electricity and converting thermal energy.
Temperature differences often exist between fluids in a system. For example, a primary fluid may have a comparatively higher temperature than that of a secondary fluid. Such temperature differences therefore provide a source of thermal energy that may be converted to another form of energy.
Additionally, in such systems, thermal energy may also be transferred between the primary fluid and the secondary fluid. That is, the primary fluid may be used to increase the temperature of the secondary fluid, via, for example, a heat conversion device such as a heat exchanger.
A heat conversion device configured for generating electricity and converting thermal energy includes a heat engine and a generator. The heat engine is configured for converting thermal energy to mechanical energy in a combination which includes a pseudoplastically pre-strained shape-memory alloy. The shape-memory alloy has a crystallographic phase changeable between austenite and martensite in response to thermal energy from a temperature difference between fluids of less than or equal to about 300° C. The generator is configured for converting mechanical energy to electricity and is driven by the heat engine.
A heat conversion system configured for generating electricity and converting thermal energy includes a source of thermal energy provided by a temperature difference of less than or equal to about 300° C. between a primary fluid having a first temperature and a secondary fluid having a second temperature that is different from the first temperature. The heat conversion system also includes the heat conversion device configured for generating electricity and converting thermal energy. In particular, the heat conversion device includes the heat engine in a combination which includes the pseudoplastically pre-strained shape-memory alloy disposed in heat exchange relationship with each of the primary fluid and the secondary fluid. The heat conversion device also includes the generator driven by the heat engine and configured for converting mechanical energy to electricity.
In one variation, a heat conversion system includes the primary fluid, the secondary fluid, and the heat conversion device. In particular, the heat conversion device has an interior configured for transferring thermal energy between the primary fluid and the secondary fluid. The heat conversion device includes the heat engine that is configured for converting at least some thermal energy to mechanical energy. Further, the heat engine and the generator are disposed within the interior of the heat conversion device. Additionally, the heat conversion system includes an electronic control unit in operable communication with the heat conversion device and configured for regulating transfer of thermal energy between the primary fluid and the secondary fluid. Further, the heat conversion system includes a transfer medium configured for conveying electricity from the heat conversion system.
The heat conversion devices and systems of the present invention provide excellent conversion of thermal energy. Additionally, the heat conversion devices and systems generate electricity. That is, the heat conversion devices and systems may be useful for not only converting thermal energy provided by a temperature difference between fluids, but also for supplying electricity. The heat conversion devices and systems may be scaled to service both household and commercial or industrial applications. And, the heat conversion devices and systems are operable and can generate electricity in response to minimal temperature differences between fluids.
The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings.
Referring to the Figures, wherein like reference numerals refer to like elements, a heat conversion device is shown generally at 10 in
Referring now to
Further, as used herein, the terminology “shape-memory alloy” refers to known alloys which exhibit a shape-memory effect and have the capability to quickly change properties in terms of stiffness, spring rate, and/or form stability. That is, the shape-memory alloy 18 may undergo a solid state phase change via crystalline rearrangement to shift between a martensite phase, i.e., “martensite”, and an austenite phase, i.e., “austenite”. Stated differently, the shape-memory alloy 18 may undergo a displacive transformation rather than a diffusional transformation to shift between martensite and austenite. In general, the martensite phase refers to the comparatively lower-temperature phase and is often more deformable than the comparatively higher-temperature austenite phase. The temperature at which the shape-memory alloy 18 begins to change from the austenite phase to the martensite phase is known as the martensite start temperature, Ms. The temperature at which the shape-memory alloy 18 completes the change from the austenite phase to the martensite phase is known as the martensite finish temperature, Mf. Similarly, as the shape-memory alloy 18 is heated, the temperature at which the shape-memory alloy 18 begins to change from the martensite phase to the austenite phase is known as the austenite start temperature, As. And, the temperature at which the shape-memory alloy 18 completes the change from the martensite phase to the austenite phase is known as the austenite finish temperature, Af.
Therefore, the shape-memory alloy 18 may be characterized by a cold state, i.e., when a temperature of the shape-memory alloy 18 is below the martensite finish temperature Mf of the shape-memory alloy 18. Likewise, the shape-memory alloy 18 may also be characterized by a hot state, i.e., when the temperature of the shape-memory alloy 18 is above the austenite finish temperature Af of the shape-memory alloy 18.
In operation, i.e., when exposed to the temperature difference of the fluids 12, 14, the shape-memory alloy 18 can change dimension upon changing crystallographic phase to thereby convert thermal energy to mechanical energy. That is, the shape-memory alloy 18 may change crystallographic phase from martensite to austenite when heated and thereby dimensionally contract if pseudoplastically pre-strained so as to convert thermal energy to mechanical energy. Conversely, the shape-memory alloy 18 may change crystallographic phase from austenite to martensite when cooled and thereby dimensionally expand when under stress so as to be pseudoplastically strained. That is, the shape-memory alloy 18 may dimensionally expand when cooled while under stress so as to reset the shape-memory alloy 18 for another cycle of converting thermal energy to mechanical energy.
The shape-memory alloy 18 may have any suitable composition. In particular, the shape-memory alloy 18 may include in combination an element selected from the group of cobalt, nickel, titanium, indium, manganese, iron, palladium, zinc, copper, silver, gold, cadmium, tin, silicon, platinum, and gallium. For example, suitable shape-memory alloys 18 may include nickel-titanium based alloys, nickel-aluminum based alloys, nickel-gallium based alloys, indium-titanium based alloys, indium-cadmium based alloys, nickel-cobalt-aluminum based alloys, nickel-manganese-gallium based alloys, copper based alloys (e.g., copper-zinc alloys, copper-aluminum alloys, copper-gold alloys, and copper-tin alloys), gold-cadmium based alloys, silver-cadmium based alloys, manganese-copper based alloys, iron-platinum based alloys, iron-palladium based alloys, and combinations of one or more of each of these combinations. The shape-memory alloy 18 can be binary, ternary, or any higher order so long as the shape-memory alloy 18 exhibits a shape memory effect, e.g., a change in shape orientation, damping capacity, and the like. A skilled artisan, in accordance with this invention, may select the shape-memory alloy 18 according to desired operating temperatures of the heat conversion device 10 (
Further, the shape-memory alloy 18 may have any suitable form, i.e., shape. For example, the shape-memory alloy 18 may have a form of a shape-changing element. That is, the shape-memory alloy 18 may have a form selected from the group of springs, tapes, wires, bands, continuous loops, and combinations thereof. Referring to
The shape-memory alloy 18 may convert thermal energy to mechanical energy via any suitable manner. For example, the shape-memory alloy 18 may activate a pulley system (shown generally in
Referring again to
Referring to
More specifically, in one variation shown in
Referring generally again to
The fluids 12, 14 may be in contact in the heat conversion device 10, or may be separated from one another in the heat conversion device 10, so long as thermal energy may be converted to mechanical energy via the heat engine 16. For example, the fluids 12, 14 may be in a heat exchange relationship, i.e., disposed with respect to each other so as to transfer thermal energy to the heat engine 16 for conversion to mechanical energy and/or disposed so as to transfer thermal energy between each other. That is, the heat conversion device 10 may be a shell-and-tube heat exchanger, a plate heat exchanger, a regenerative heat exchanger, a plate fin heat exchanger, a fluid heat exchanger, a waste heat recovery heat exchanger, a dynamic scraped surface heat exchanger, a phase-change heat exchanger, a direct contact heat exchanger, a spiral heat exchanger, and any heat exchange combinations thereof.
In the variation including the heat exchanger as the heat conversion device 10, the heat exchanger may have a configuration of fluid flow selected from the group of parallel-flow, counter-flow, cross-flow, and combinations thereof. As used herein, the terminology “parallel-flow” refers to a configuration in which the fluids 12, 14 each enter a same end of the heat exchanger and travel parallel to each other through the heat exchanger. In contrast, the terminology “counter-flow” refers to a configuration in which the fluids 12, 14 enter the heat exchanger at opposite ends. The terminology “cross-flow” refers to a configuration in which the fluids 12, 14 flow approximately perpendicularly to each other through the heat exchanger. It is further contemplated that the heat conversion device 10 may include other elements such as, but not limited to, filters, valves, baffles, controls, sensors, and pressure regulators.
Referring again to
The primary fluid 12 and the secondary fluid 14 may each be selected from the group of gases, liquids, fluidized beds of solids, and combinations thereof. Likewise, the primary fluid 12 may have a different form, i.e., phase, than the secondary fluid 14. For example, the primary fluid 12 may be a liquid and the secondary fluid 14 may be a gas. Further, the primary fluid 12 may be the same as or different from the secondary fluid 14. In one variation, the primary fluid 12 and the secondary fluid 14 may each be water, but the water of the primary fluid 12 may have a first temperature that is higher than the second temperature of the water of the secondary fluid 14.
Referring again to
However, in one variation of the heat conversion system 42, the heat conversion device 10 may be the heat exchanger set forth above, and may transfer the majority of the thermal energy between the primary fluid 12 and the secondary fluid 14. That is, the heat conversion device 10 may transfer thermal energy from the primary fluid 12 to the secondary fluid 14 to thereby increase the second temperature of the secondary fluid 14. However, it is to be appreciated that the heat conversion device 10 may alternatively transfer thermal energy from the secondary fluid 14 to the primary fluid 12, depending upon the temperature difference between the primary fluid 12 and the secondary fluid 14.
As shown generally in
Further, the shape-memory alloy 18 may change both modulus and dimension upon changing crystallographic phase to thereby convert thermal energy to mechanical energy. More specifically, the shape-memory alloy 18, if pseudoplastically pre-strained, may dimensionally contract upon changing crystallographic phase from martensite to austenite and may dimensionally expand, if under tensile stress, upon changing crystallographic phase from austenite to martensite to thereby convert thermal energy to mechanical energy. Therefore, for any condition wherein the temperature difference ΔT exists between the first temperature of the primary fluid 12 and the second temperature of the secondary fluid 14, i.e., wherein the primary fluid 12 and the secondary fluid 14 are not in thermal equilibrium, the shape-memory alloy 18 may dimensionally expand and contract upon changing crystallographic phase between martensite and austenite. And, the change in crystallographic phase of the shape-memory alloy 18 is sufficient to drive the generator 20.
In operation, with reference to the heat conversion system 42 of
Referring again to
It is to be appreciated that the primary fluid 12 and the secondary fluid 14 may not pass through the housing 44. That is, for applications including a liquid primary fluid 12 and a liquid secondary fluid 14, the frame 22 (
Alternatively, the primary fluid 12 and the secondary fluid 14 may pass through the housing 44, but may remain separated within the housing 44. For example, the housing 44 may include inlets and outlets for each of the primary fluid 12 and the secondary fluid 14, and the primary fluid 12 may be separated from the secondary fluid 14 by a seal or barrier.
Although not shown, it is also contemplated that the primary fluid 12 and the secondary fluid 14 may be contained by, and separated within, the housing 44. For example, in this arrangement, the primary fluid 12 and the secondary fluid 14 may each be a liquid or a gas that may be heated or cooled by other fluids passing across the housing 44 during operation of the heat conversion device 10. In this arrangement, the heat engine 16 may be disposed within, for example, a shell (not shown), and adjacent to and in contact with, for example, a tube (not shown) of the heat conversion device 10. Therefore, a comparatively warmer fluid may pass through the tube of the heat conversion device 10 while a comparatively cooler fluid passes through the shell of the heat conversion device 10. The primary fluid 12 and the secondary fluid 14 may thus be warmed and/or cooled by convection or conduction by the fluids within the shell and tube of the heat conversion device 10. The primary fluid 12 and the secondary fluid 14 may be separated within the housing 44, for example by a physical barrier. And, the heat engine 16 may straddle the barrier so that the shape-memory alloy 18 protrudes into each of the primary fluid 12 and the secondary fluid 14.
Referring again to
Referring now to
As also shown in
Referring again to
Likewise, the heat conversion system 42 further includes an output circuit, shown generally at 54 in
It is to be appreciated that for any of the aforementioned examples or configurations, the heat conversion device 10 and/or the heat conversion system 42 may include a plurality of heat engines 16 and/or a plurality of generators 20. That is, one heat conversion device 10 may include more than one heat engine 16 and/or generator 20. For example, one heat engine 16 may drive more than one generator 20. Likewise, one heat conversion system 42 may include more than one heat conversion device 10, each including at least one heat engine 16 and generator 20. In variations including more than one heat conversion device 10, the heat conversion devices 10 may be connected in series or in parallel. That is, if a plurality of heat conversion devices 10 are arranged in parallel (not shown), each heat conversion device 10 may be disposed in contact with a common primary fluid 12. Conversely, if a plurality of heat conversion devices 10 are arranged in series (not shown), the primary fluid 12 of one heat conversion device 10 may also be the secondary fluid 14 of another heat conversion device 10.
Heat conversion devices 10 and systems 42 of the present invention provide excellent conversion of thermal energy. Additionally, heat conversion devices 10 and systems 42 generate electricity EE. That is, heat conversion devices 10 and systems 42 may be useful not only for converting thermal energy and/or transferring thermal energy between fluids 12, 14, but also for supplying electricity EE. Heat conversion devices 10 and systems 42 may be scaled to service both household and commercial or industrial applications 56. And, heat conversion devices 10 and systems 42 are operable and can generate electricity EE in response to minimal temperature differences between fluids. As such, heat conversion devices 10 and heat conversion systems 42 harvest thermal energy so as to convert thermal energy to mechanical energy and to electricity EE.
While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.
