Thermal storage unit and methods for using the same to heat a fluid
A thermal storage unit having at least one annular flow channel formed between an inner and outer member is provided. The thermal storage unit uses conventional mill products to create annular flow channels that are coupled to each other via transverse channels for allowing various fluid routing arrangements and piping connections, and that economically maximize the surface area of flow in contact with the thermal mass included in the inner and outer members. This enables the thermal storage unit to economically provide heat storage as well as effective heat delivery and pressure containment for a fluid flowing through the annular channel. The thermal storage unit's size and shape are optimized and its performance enhanced by providing features for maintaining the position of the inner member within the outer member, features for providing support for the unit, and insulation.
This application is a continuation-in-part of U.S. patent application Ser. No. 10/738,825, filed Dec. 16, 2003.
BACKGROUND OF THE INVENTIONThis invention relates to thermal storage units (TSUs). More particularly, this invention relates to TSUs that provide sensible heat thermal energy storage and delivery in a way that increases efficiency and reduces costs compared to known TSUs.
TSUs are well known and are often used in power delivery systems, such as compressed air storage (CAS) systems and thermal and compressed air storage (TACAS) systems. Such systems, often used to provide an available source of electrical power, often use compressed air to drive a turbine which powers an electrical generator.
In TACAS systems, it is desirable to heat the compressed air prior to reaching the inlet port of the turbine. It is known that heated air, as opposed to ambient or cool air, enables the turbine to operate more efficiently. Therefore, a mechanism or system is needed to heat the air before providing it to the turbine. One approach is to use a suitable type of fuel-combustion system. Another approach is to use a TSU. While fuel-combustion systems usually emit polluting gases, TSUs may be preferable over fuel-combustion systems at least because they are not associated with such harmful emissions.
Although TSUs may offer advantages over fuel-combustion systems, existing TSUs have several shortcomings, as discussed below.
One known configuration of a TSU is shown in
Another known TSU uses tube flow through elongated cavities embedded in a solid medium. As shown in
Therefore, it can be seen that the TSUs shown in
In view of the foregoing, it is an object of this invention to provide a low-cost TSU that provides efficient heat storage, heat delivery and pressure containment.
SUMMARY OF THE INVENTIONThis and other objects of the present invention are accomplished in accordance with the principles of the present invention by providing a TSU having at least one flow channel disposed annularly about an axis that is substantially parallel to the TSU's longitudinal axis. The annular channel may be contained between an inner member and an outer member, both of which may include thermal mass or thermal storage material having desirable energy or heat storage properties and may be fabricated using standard mill products. The annular channel may be coupled to a port or pipe on each end of the channel for either providing fluid thereto or projecting fluid therefrom. In one embodiment of the present invention, the TSU may include a single annular flow channel disposed about the TSU's longitudinal axis. In another embodiment of the present invention, the TSU may include multiple parallel annular flow channels, each being contained between the outer member and a different inner member. In yet another embodiment of the present invention, the TSU may include multiple parallel annular flow channels that may be coupled to each other via transverse channels such that various fluid routing arrangements and piping connections are made possible within the TSU. The TSU's size and shape may be optimized for manufacturing, packaging, transporting and storing.
The inner and outer members of the TSU may be heated to effectively heat a fluid flowing through the annular channel. Efficient heat transfer is realized with the annular channel because the ring-like channel maximizes the surface area of fluid contact with the inner and outer members. The inner members may be centered, offset or tilted in order to achieve different heating profiles. Moreover, insulation may be added to the TSU to limit heat loss from the TSU.
In addition to providing energy storage and efficient heat transfer, the outer member provides structural support for the TSU, thereby enabling it to contain pressurized fluids. For example, the TSU may be used in a TACAS system whereby compressed air may be sensibly heated in the TSU. The heated and compressed air may then drive a turbine which powers an electrical generator to provide an electrical output. Features that enable single-ended or same-side piping and mounting to supporting structures may be added to the TSU to limit the effects of thermal growth and provide alternative methods to couple the TSU to the TACAS system. The TACAS system may also include an inert gas purging system that minimizes fouling in the TSU channel(s).
BRIEF DESCRIPTION OF THE DRAWINGSThe above and other features of the present invention, its nature and various advantages will be more apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which:
TSU 100 may include three main compartments, namely, middle portion 110 and end portions 120. Middle portion 110 may be defined as the portion of TSU 100 that is between lines 101, whereas end portions 120 may be defined as the portions of TSU 100 that extend beyond lines 101 to both ends of TSU 100. When fluid is applied to TSU 100, it is directed into one of end portions 120, flows through middle portion 110, and is directed out of the other end portion 120. Fluid may be matter in the liquid, gas or plasma phase.
When fluid is routed through middle portion 110, it flows in a ring-like channel, which is referred to as annular flow channel 115. Annular channel 115 may extend generally along middle portion 110, between outer member 114 and inner member 112. Annular channel 115 may extend along the length of middle portion 110, in a direction that is substantially parallel to longitudinal axis 150.
Referring back to
End portions 120, which may be identical, may each include a hollow or tubular enclosure, namely, port 125, within a portion of outer member 114 that extends into each of the end portions. Port 125 may be coupled to the portion of annular channel 115 that extends into the end portion for either providing fluid thereto or projecting fluid therefrom. In this arrangement, annular channel 115 may decrease in mean diameter from a point within TSU 100 (e.g., a point proximal to line 101) to the point on the end portion where port 125 couples to annular channel 115. This arrangement enables fluid delivery to and from the TSU. Port 125 may be also seen in
In a preferred embodiment of the present invention, inner member 112 may be constructed from solid material(s) that have adequate thermal conductivity and other desirable thermal properties such as high volumetric heat capacity. Outer member 114 may be constructed from the same material(s) as inner member 112. Therefore, both inner and outer members 112 and 114 may provide thermal mass for energy storage. Alternatively, outer member 114 may be constructed from material(s) capable of withstanding high pressure, in addition to possessing desirable thermal properties. Such materials may include iron, steel, aluminum, any alloys thereof or any other suitable material(s).
According to the principles of the present invention, TSU 100 may be heated to a desired temperature by heating inner and outer members 112 and 114. Fluid may then be heated by routing it through TSU 100 such that it enters one of ports 125 at one end, flows through annular channel 115, and exits through port 125 at the opposite end.
Inner member 112 and/or outer member 114, may be heated through radiation by means of an external or internal heater. For example, a ceramic fiber heater that annularly surrounds—without coming into contact with—TSU 100 may heat both inner and outer members 112 and 114 through radiation when actuated. Alternatively, one or more heating rods may be placed into one or more cavities extending through at least a portion of or the entire length of TSU 100. When such heating rods are actuated, they radiate heat energy to heat both inner and outer members 112 and 114.
Due to the thermal conductivity of the inner and outer members 112 and 114, heat energy is effectively conducted through these members. Moreover, because annular channel 115 maximizes the surface area of fluid contact with the thermal mass in inner and outer members 112 and 114, the fluid flowing in the channel may be sensibly heated through convection from inner member 112 and/or outer member 114 to the fluid. Accordingly, heating either member or both enables the efficient heating of the fluid flowing through the channel. Thus, when fluid having a predetermined temperature (e.g., ambient temperature) is supplied to TSU 100, its temperature rises as it flows through annular channel 115 formed between inner and outer members 112 and 114.
Persons skilled in the art will appreciate that electronic circuitry (not shown) may be used to monitor the temperature of TSU 100 and control the mechanism (e.g., the external ceramic heater or internal heating rods) used to heat TSU 100. A more detailed discussion of such electronics is provided below in connection with
An example of a fluid that may be routed through TSU 100 is compressed air. Compressed air may be heated using TSU 100, as discussed above. Moreover, TSU 100 provides structural integrity against pressure exerted from the compressed air flowing in the channel. This is due to the fact that outer member 114, which contains material capable of withstanding high pressure, cylindrically surrounds the annular channel, thereby containing the pressure exerted by the air on the outer member. Therefore, not only is TSU 100 adequate for providing heat storage, TSU 100 is conducive to high pressure operation, unlike the parallel-plate channel flow TSU 10 of
Moreover, unlike drilling multiple small-diameter holes that extend through the entire length of a bar in order to implement tube flow as shown in connection with TSU 20 of
Like TSU 100 of
Each one of annular channels 215 may be disposed annularly about an axis that is substantially parallel to longitudinal axis 250, such as axis 251. Each annular channel 215 may be formed by drilling or casting a relatively large-diameter hole in a round bar, which may be referred to as outer member 214, and inserting a smaller round bar, which may be referred to as inner member 212, such that each inner member 212 extends at least along the length of middle portion 210. Because the holes in outer member 214 are relatively large, at least compared to the holes bored through TSU 20 of
In a preferred embodiment of the present invention, each mean diameter of annular channels 215 may be substantially equal in length. Moreover, inner and outer members 212 and 214 may be constructed from the same material as members 112 and 114 of TSU 100 of
The present invention may be used in many applications.
The following discussion of TACAS system 600 is not intended to be a thorough explanation of the components of a TACAS, but rather an illustration of how TSU 100 or 200 can enhance the performance of a TACAS system. For a detailed description of a TACAS system, see commonly-assigned, co-pending U.S. patent application Ser. No. 10/361,728, filed Feb. 5, 2003, which is hereby incorporated by reference herein in its entirety.
As shown in
The hot air emerging from TSU 100 may flow against the turbine rotor (not shown) of turbine 641 and drive turbine 641, which may be any suitable type of turbine system (e.g., a radial-flow turbine). In turn, turbine 641 may drive electrical generator 642, which produces electric power and provides it to electrical output 650.
Also shown in
Not only is system 600 advantageous because it uses a relatively inexpensive and efficient TSU, it is also non-polluting. That is because, unlike conventional systems that use fuel-combustion systems to provide hot air to the turbine, it does not require a fuel supply to heat the air that is being supplied to turbine 641. Instead, TSU 100 may be powered by electrical input 610, which provides the energy needed to heat the compressed air, while providing effective pressure containment. For example, TSU 100 may include an external or internal radiant heater, as discussed above, which may be powered by electrical input 610. System 600 therefore provides the benefits of heating compressed air from pressure tank 623 before it is supplied to turbine 641, without producing the harmful emissions associated with combustion systems.
It will also be understood by persons skilled in the art that, alternatively, the thermal storage material of TSU 100 may be heated by any other suitable type of heating system. For example, a resistive heater may provide a heat source that is in physical contact with the thermal storage material of TSU 100 and may heat this material to a predetermined temperature. Alternatively, electrically conductive thermal storage materials, such as iron, may be heated inductively using induction heating circuitry that causes current to circulate through and heat the thermal storage material of TSU 100. Thus, the invention is not limited to the specific heating manners discussed above.
TACAS system 600 may also include control circuitry 620 which may be coupled to both TSU 100 and electrical input 610. Control circuitry 620 may include means for measuring the temperature of TSU 100. Control circuitry 620 may also include electric circuitry for controlling the temperature of TSU 100. Control circuitry 620 may control the temperature of TSU 100 by, for example, controlling the electric power provided to the heat source. This may be achieved by providing instructions to electrical input 610, such as instructions to activate, deactivate, increase or decrease the output of electrical input 610. Control circuitry 620, along with electrical input 610, may therefore be used to monitor and control the temperature of TSU 100. As a result, the TSU 100 may be heated to and maintained at a desired temperature.
Moreover, valve 632 may be coupled to piping (not shown) that bypasses TSU 100 and feeds into turbine 641 along with the output from TSU 100. By controlling the portion of the total compressed air flow through the TSU, the ratio of heated to non-heated air provided to turbine 641 may be modified, thereby providing another means for controlling the temperature of the air being supplied to the turbine.
Another advantage of utilizing TSU 100 is that larger pressure tanks are not required as is the case with compressed air storage systems that do not utilize thermal storage units or combustion systems.
Like TSU 200 of
TSU 300 may also include one or more transverse flow channels formed by transverse members 330, through which fluid may flow. Two adjacent annular channels 315 may be coupled through transverse member 330 close to one end of TSU 300. One of these two annular channels may be coupled to a different annular channel 315 that is adjacent to it through another transverse member 330 away from the first end and/or close to the other end of TSU 300. Transverse members need not extend through the entire width of TSU 300, so long as each transverse member couples two adjacent annular channels to each other such that they are in fluidic communication with one another.
Two transverse members 330 may be disposed close to a first end of TSU 300 wherein one transverse member 300 may couple a set of annular channels 315 that is different than the set of annular channels 315 coupled by the other member. At least one transverse member 330 may be disposed close to the other end of TSU 300 for coupling a set of annular channels 315 that is different than the sets coupled by the members disposed close to the first end. The sets of annular channels coupled by two members disposed close to the same end of TSU 300 preferably do not have an annular channel in common. Moreover, the sets of annular channels coupled by two members disposed close to opposite ends of TSU 300 preferably do have one annular channel in common. Furthermore, the two members disposed close to the same end preferably are parallel to each other and perpendicular to the at least one member disposed close to the other end.
The foregoing arrangement of annular channels 315 and transverse members 330 allows for much flexibility in routing of fluid through TSU 300. For example, fluid may be routed through one or more annular channels simultaneously via different paths. Such an arrangement also enables fluid to be supplied to and retrieved from the same end of TSU 300, provided the fluid flows through an even number of annular channels. Examples of different fluid flow arrangements are depicted in
Similarly, several transverse members may be omitted when fabricating TSU 300 according to another alternative embodiment of the present invention. Specifically, multiple TSUs 300 may be coupled together in order to provide even longer flow paths. For example,
The foregoing flow arrangements are only illustrative of the principles of the present invention. Various modifications and fluid routing arrangements can be implemented by those skilled in the art without departing from the scope and spirit of the invention.
In a preferred embodiment of the present invention, inner and outer members 312 and 314 may be constructed from the same material as members 112, 212, 114 and 214 of TSUs 100 and 200 of
Because TSU 300 utilizes annular flow channels, it provides efficient energy storage, heat transfer and pressure containment consistent with that discussed above in connection with TSU 100. Unlike TSUs 100 and 200 of
Moreover, similar to TSUs 100 and 200, TSU 300 can be fabricated relatively easily without incurring severe costs, as compared to drilling multiple small-diameter holes that extend through the entire length of a bar in order to implement tube flow as shown in connection with TSU 20 of
Centering inner members 312, as shown in
In alternative embodiments of the present invention, inner member 312 may be positioned as shown in
Positioning inner members 312, as shown in
Centering, offsetting or tilting inner member 312 as shown in
Other features, such as the ones shown in
The features shown in
Alternatively, features to prevent fluid flow blockage may include machining, forging or welding the ends of inner member 312, or using any other appropriate method in order to maintain a gap between inner members 312 and outer member 314 or drilled plug 2802 discussed in connection with
As discussed above, TSU 300 allows for various fluid routing arrangements that enable retrieving fluid from the same end it is supplied. Allowing for various fluid routing arrangements also provides more flexibility in choosing optimum piping connections to TSU 300 in order to supply and retrieve fluid to and from the TSU. This aspect is further enhanced by the existence of transverse members 330, which allow for making piping connections to the side of TSU 300. Examples of such piping configurations are illustrated in
For example,
As another example,
An alternative piping arrangement to that of
As yet another example,
As yet another example,
An alternative piping arrangement to that of
As yet another example,
As illustrated by some of the examples discussed in connection with
Like TSUs 100 and 200, TSU 300 may be heated to a desired temperature by heating inner and/or outer members 312 and 314 through radiation, by placing one or more heating rods into one or more cavities extending through at least a portion of or the entire length or width of TSU 300, or by any method or apparatus disclosed in U.S. patent application Ser. No. ______, filed Sep. ______, 2004 (Attorney Docket No. AP-53), which is hereby incorporated by reference herein in its entirety, or by any other suitable method or apparatus.
Heating a TSU, especially for extended time periods at elevated temperatures, may result in dissipation of thermal energy through its walls in the form of heat. To counter such heat loss, insulating material may be coupled to the outer surface of the unit, as can be seen in
For example, insulating material fabricated in single or multiple layers with stepped interfaces between adjacent faces may be used. Effective insulation material would not corrode or degrade significantly over time. Preferably, such material may be inert, such as ceramic microporous material. Moreover, such material may be in either pressed rigid board form or fabric-coated stitched form, having thermal conductivities ranging from 0.023 W/m-K to 0.050 W/m-K. The thickness of such high efficiency insulation material need not be considerable to attain a substantial reduction in heat loss. Therefore, not only does a TSU surrounded by or coated with such material benefit from a reduction in heat loss, which reduces the cost of maintaining a TSU, using such material does not result in a significant increase in the volume of the unit. This, in turn, does not substantially affect packaging, transporting and storing of the unit negatively.
Heating a TSU may also lead to thermal growth due to the expansion of the materials used to fabricate it. This may have harmful effects on the system in which the unit is used. For example, axial expansion of a unit having piping connections on opposite ends to a thermal storage system may strain or stress and therefore fracture such piping connections.
One way to avoid such effects is to design the TSU such that piping connections to other portions of the system need not be made on opposite ends of the unit. As evidenced by the discussion relating to
Moreover, features, such as the ones illustrated in
TSU 300 may be mounted to a support structure in order to minimize the impact of thermal growth of outlet pipe 3604 which may heat substantially. By mounting TSU 300 to a support structure close to the end of TSU 300 where the inlet and outlet pipes 3602 and 3604 are situated, the outlet pipe may grow in a direction away from the TSU and opposite to the direction of growth of the TSU, thereby allowing for unrestrained growth of the outlet pipe that does not impact TSU 300. TSU 300 may be coupled to the support structure through any of fixtures depicted in
Similar to TACAS system 600 of
TACAS system 3800 benefits from the advantages discussed in connection with TACAS system 600. Moreover, because TSU 300 is coupled to other components of TACAS system 3800 such that piping connections to the other components are made on the same end of TSU 300, the opposite end of TSU 300 may remain unsecured. As described aove, this limits or avoids the negative impact of thermal expansion on the piping connections and on TACAS system 3800.
TACAS system 3800 also includes gas tank 3823 and valve 3832. Gas tank 3823 may contain a pressurized inert purge gas. After electric power is needed from system 3800, and compressed air from pressure tank 623 is routed to TSU 300, heated and provided to turbine 641, valve 3832 may be actuated such that the inert gas is routed from gas tank 3823 to TSU 300. The inert gas may be used to purge and replace some or all of the air present in TSU 300. Valve 3832 may be used to control the portion of inert gas supplied to TSU 300, thereby modifying the ratio of inert gas to air in TSU 300. Preferably, gas tank 3823 may contain an inert gas that is heavier than air, such as argon. TSU 300 may be oriented such that the piping connections to other components of TACAS system 3800 are above the body of TSU 300, thereby allowing gravity to assist the purge gas to displace the air in TSU 300 and remain in TSU 300.
The benefit of using an inert gas to purge the air in TSU 300 is the prevention of oxidation that could cause fouling of the flow channels in the TSU. Fouling refers to the build-up of an oxide residue layer on the internal surfaces of the flow channels, thereby partially or completely blocking the flow channels and degrading performance. High temperature operation increases the rate of oxidation in the flow channels. Accordingly, fouling may be prevented by lowering the operating temperature which would require a larger TSU for the system to operate efficiently. This, in turn, may lead to increased manufacturing, packaging, transporting and storing costs relating to the TSU. Alternatively, occasionally substituting an inert gas for air in a TSU reduces the rate of oxidation in the TSU's flow channels. Therefore, implementing a purge gas system in a thermal and compressed air system, or any other system that utilizes a TSU, may be a more desirable alternative.
The present invention was presented in the context of industrial backup utility power. The present invention may be alternatively implemented in a continuously operating electrical generation system such as a continuously operating TACAS system. Such a system may use a compressor that constantly provides compressed air to a TSU that may be continuously heated to ensure that the air is sensibly heated before being provided to a constantly operating turbine.
Alternatively, the present invention may be used in any application associated with generating power, such as in thermal and solar electric plants. Furthermore, the present invention may be used in any other application where thermal storage, fluid heating or heated fluid delivery may be desirable.
The above described embodiments of the present invention are presented for purposes of illustration and not of limitation, and the present invention is limited only by the claims which follow.
Claims
1. A thermal storage unit having a longitudinal axis, the unit comprising:
- a first annular flow channel disposed about an axis parallel to the longitudinal axis;
- a second annular flow channel disposed adjacently to the first annular flow channel about an axis parallel to the longitudinal axis;
- a first transverse channel coupling the first and second annular flow channels at a first location along the longitudinal axis that is proximal to an end of the unit;
- a third annular flow channel disposed adjacently to the second annular flow channel about an axis parallel to the longitudinal axis; and
- a second transverse channel coupling the second and third annular flow channels at a second location along the longitudinal axis that is distal from the end of the unit.
2. The thermal storage unit of claim 1 wherein each of the first, second and third transverse channels is perpendicular to the first, second and third annular flow channels.
3. The thermal storage unit of claim 1 further comprising:
- a fourth annular flow channel disposed adjacently to the third annular flow channel about an axis parallel to the longitudinal axis; and
- a third transverse channel coupling the third and fourth annular flow channels at a third location along the longitudinal axis that is proximal to the end of the unit.
4. The thermal storage unit of claim 3 wherein the first and third transverse channels are parallel to one another and perpendicular to the second transverse channel.
5. The thermal storage unit of claim 1 further comprising a fourth transverse channel coupling the first and fourth annular flow channels at a fourth location along the longitudinal axis that is distal from the end of the unit.
6. The thermal storage unit of claim 5 wherein each of the first, second, third and fourth transverse channels is perpendicular to the first, second, third and fourth annular flow channels.
7. The thermal storage unit of claim 5 wherein the first and third transverse channels are parallel to one another, the second and third transverse channels are parallel to one another and perpendicular to the first and third transverse channels.
8. The thermal storage unit of claim 3 wherein the first and second annular flow channels are in fluidic communication with each other through the first transverse channel, the second and third annular flow channels are in fluidic communication with each other through the second transverse channel and the second and third annular flow channels are in fluidic communication with each through the third transverse channel.
9. The thermal storage unit of claim 5 wherein the first and second annular flow channels are in fluidic communication with each other through the first transverse channel, the second and third annular flow channels are in fluidic communication with each other through the second transverse channel, the second and third annular flow channels are in fluidic communication with each through the third transverse channel and the third an fourth annular flow channels in fluidic communication with each other through the fourth transverse channel.
10. A method for using the thermal storage unit of claim 8, the method comprising:
- providing a fluid to thermal storage unit such that: the fluid flows through the first annular flow channel to the first transverse channel, the fluid flows through the first transverse channel to the second annular flow channel, the fluid flows through the second annular flow channel to the second transverse channel, the fluid flows through the second transverse channel to the third annular flow channel, the fluid flows through the third annular flow channel to the third transverse channel, and the fluid flows through the third transverse channel to the fourth annular flow channel; and
- retrieving the fluid from the thermal storage unit after the fluid has flown through the fourth annular flow channel.
11. The method of claim 10 further comprising heating the thermal storage unit using a heat source.
12. A method for using the thermal storage unit of claim 9, the method comprising:
- providing a fluid to thermal storage unit such that the fluid flows through a first and second path simultaneously, the first path comprising: the fluid flowing through the first annular flow channel to the first transverse channel, the fluid flowing through the first transverse channel to the second annular flow channel, and the fluid flowing through the second annular flow channel to the second transverse channel,
- the second path comprising: the fluid flowing through fourth transverse channel to the fourth annular flow channel, the fluid flowing through fourth annular flow channel to the third transverse channel, and the fluid flowing through the third transverse channel to the third annular flow channel; and
- retrieving the fluid from the thermal storage unit after the fluid has flown through the second transverse channel in the first path and after the fluid has flown through the third annular flow channel in the second path.
13. The method of claim 12 further comprising heating the thermal storage unit using a heat source.
14. A method for using the thermal storage unit of claim 9, the method comprising:
- providing a fluid to thermal storage unit such that the fluid flows through a first and second path simultaneously, the first path comprising: the fluid flowing through the first annular flow channel to the first transverse channel, and the fluid flowing through the first transverse channel to the second annular flow channel,
- the second path comprising: the fluid flowing through fourth transverse channel to the fourth annular flow channel, the fluid flowing through fourth annular flow channel to the third transverse channel, the fluid flowing through the third transverse channel to the third annular flow channel, and the fluid flowing through the third annular flow channel to the second transverse channel; and
- retrieving the fluid from the thermal storage unit after the fluid has flown through the second annular flow channel in the first path and after the fluid has flown through the second transverse channel in the second path.
15. The method of claim 14 further comprising heating the thermal storage unit using a heat source.
16. A method for adding piping connections to the thermal storage unit of claim 8 wherein the end of the thermal storage unit is a first end, the thermal storage unit having a second end proximal to the second location, the method comprising:
- about the second end, coupling a first pipe to the first annular flow channel for providing fluid to the thermal storage unit.
17. The method of claim 16 further comprising:
- about the second end, coupling a second pipe to one of the channels from the group consisting of the second annular flow channel, the third annular flow channel, the fourth annular flow channel and the second transverse channel for retrieving fluid from the thermal storage unit.
18. The method of claim 17 further comprising coupling at least one beam to the thermal storage unit about the second end for securing the thermal storage unit to a support structure.
19. The method of claim 18 wherein the at least one beam is coupled to the thermal storage unit through one of the fixtures from the group consisting of at least one threaded rod and at least one bushing.
20. The method of claim 18 wherein the support structure comprises a plurality of apertures for placing heating rods in order to heat the thermal storage unit.
21. The method of claim 18 wherein the support structure comprises insulation material coupled to the thermal storage unit for preventing heat loss from the thermal storage unit.
22. The method of claim 21 wherein the insulation material comprises inert ceramic microporous material.
23. The method of claim 21 wherein the insulation material is in pressed rigid board form.
24. The method of claim 21 wherein the insulation material is in fabric-coated stitched form.
25. The method of claim 21 wherein the support structure further comprises an envelope for protecting the insulation material coupled to the thermal storage unit.
26. A method for adding piping connections to the thermal storage unit of claim 9 wherein the end of the thermal storage unit is a first end, the thermal storage unit having a second end proximal to the second and fourth locations, the method comprising:
- about the second end, coupling a first pipe to one of the channels from the group consisting of the first annular flow channel and the second transverse channel for providing fluid to the thermal storage unit.
27. The method of claim 26 further comprising:
- about the second end, coupling a second pipe to one of the channels from the group consisting of the second annular flow channel, the third annular flow channel, the fourth annular flow channel, the second transverse channel and the fourth transverse channel for retrieving fluid from the thermal storage unit.
28. The method of claim 27 further comprising coupling at least one beam to the thermal storage unit about the second end for securing the thermal storage unit to a support structure.
29. The method of claim 28 wherein the at least one beam is coupled to the thermal storage unit through one of the fixtures from the group consisting of at least one threaded rod and at least one bushing.
30. The method of claim 28 wherein the support structure comprises a plurality of apertures for placing heating rods in order to heat the thermal storage unit.
31. The method of claim 28 wherein the support structure comprises insulation material coupled to the thermal storage unit for preventing heat loss from the thermal storage unit.
32. The method of claim 31 wherein the insulation material comprises inert ceramic microporous material.
33. The method of claim 31 wherein the insulation material is in pressed rigid board form.
34. The method of claim 31 wherein the insulation material is in fabric-coated stitched form.
35. The method of claim 31 wherein the support structure further comprises an envelope for protecting the insulation material coupled to the thermal storage unit.
36. A backup energy system comprising:
- the thermal storage unit of claim 1 for heating a fluid;
- a turbine coupled to the thermal storage unit for receiving the heated fluid, the received heated fluid driving the turbine; and
- an electrical generator for providing power when the turbine is driven by the heated fluid.
37. The backup energy system of claim 36 further comprising:
- a heating system for heating the thermal storage unit; and
- means for maintaining the thermal storage unit at a predetermined temperature.
38. The backup energy system of claim 36 wherein the fluid is compressed air, the system further comprising a storage tank containing compressed air for providing the compressed air to the thermal storage unit.
39. The backup energy system of claim 38 further comprising:
- a storage tank containing an inert gas for purging the compressed air in the thermal storage unit; and
- a valve coupled to the storage tank for providing the inert gas to the thermal storage unit.
40. The backup energy system of claim 39 wherein the inert gas is a inert gas that is heavier than air.
41. The backup energy system of claim 39 wherein the inert gas is argon.
42. A thermal storage unit comprising:
- at least two annular flow channels disposed adjacently to one another, each annular flow channel being formed between an inner cylindrical surface of a single first member and an outer cylindrical surface of a second member, the outer cylindrical surface having a diameter smaller than the inner cylindrical surface; and
- a transverse member coupling the at least two annular flow channels to each other such that they are in fluidic communication with one another.
43. The thermal storage unit of claim 42, the thermal storage unit having a longitudinal axis, each annular flow channel being disposed parallel to the unit's longitudinal axis.
44. The thermal storage unit of claim 43 wherein the transverse member is perpendicular to the unit's longitudinal axis.
45. The thermal storage unit of claim 43 wherein each one of the second members has a longitudinal axis, at least one second member being disposed such that its longitudinal axis is parallel to the unit's longitudinal axis.
46. The thermal storage unit of claim 45 wherein the at least one of the second members is positioned such that it does not come in contact with the first member.
47. The thermal storage unit of claim 45 wherein the at least one of the second members is positioned such that it comes in contact with the first member.
48. The thermal storage unit of claim 43 wherein each one of the second members has a longitudinal axis, at least one second member being disposed such that its longitudinal axis is not parallel to the unit's longitudinal axis.
49. The thermal storage unit of claim 48 wherein the at least one of the second members is positioned such that it comes in contact with the first member.
50. The thermal storage unit of claim 43 wherein movement of at least one of the second members in a direction transverse to the unit's longitudinal axis is restricted through a fixture coupled to the least one of the second members.
51. The thermal storage unit of claim 43 wherein movement of at least one of the second members in a direction parallel to the unit's longitudinal axis is restricted through a fixture coupled to the least one of the second members.
52. The thermal storage unit of claim 42 wherein at least a portion is removed from at least one of the second members.
53. A method for fabricating the thermal storage unit of claim 42, the method comprising:
- creating a plurality of holes in a block of solid material to form the first member and the transverse member; and
- inserting the second members into the first member to form the at least two annular flow channels.
54. The method of claim 53 wherein each of the block of solid material and the second members comprises thermal storage material.
55. The method of claim 54 wherein the thermal storage material is constructed from one of the materials from the group consisting of iron, aluminum and steel.
56. The method of claim 53 further comprising sealing the plurality of holes with a plurality of plugs wherein a first plug is drilled to form an inlet for providing a fluid to the thermal storage unit and wherein a second plug is drilled to form an outlet for retrieving the fluid from the thermal storage unit.
57. A method for adding piping connections to the thermal storage unit of claim 42, the method comprising:
- coupling a first pipe to a first one of the at least two annular flow channels for providing fluid to the first one of the at least two annular flow channels; and
- coupling a second pipe to a second one of the at least two annular flow channels for retrieving fluid from the second one of the at least two annular flow channels.
58. A backup energy system comprising:
- the thermal storage unit of claim 42 for heating a fluid;
- a turbine coupled to the thermal storage unit for receiving the heated fluid, the received heated fluid driving the turbine; and
- an electrical generator for providing power when the turbine is driven by the heated fluid.
59. The backup energy system of claim 58 further comprising:
- a heating system for heating the thermal storage unit; and
- means for maintaining the thermal storage unit at a predetermined temperature.
60. The backup energy system of claim 58 wherein the fluid is compressed air, the system further comprising a storage tank containing compressed air for providing the compressed air to the thermal storage unit.
61. The backup energy system of claim 60 further comprising:
- a storage tank containing an inert gas for purging the compressed air in the thermal storage unit; and
- a valve coupled to the storage tank for providing the inert gas to the thermal storage unit.
62. The backup energy system of claim 61 wherein the inert gas is a inert gas that is heavier than air.
63. The backup energy system of claim 61 wherein the inert gas is argon.
Type: Application
Filed: Sep 17, 2004
Publication Date: Jun 16, 2005
Inventors: Robert Hudson (Austin, TX), David Perkins (Austin, TX), Donald Hudson (Austin, TX), David Beatty (Austin, TX), Donald Stamets (Cedar Park, TX), Joseph Pinkerton (Austin, TX)
Application Number: 10/943,293