FLUID FLOW SIMULATION DEVICES, FLUID HEATING CHAMBERS, AND ASSOCIATED METHODS

A fluid flow simulation device may include a heating chamber configured to heat a conductive fluid with one or more electrodes. The fluid flow simulation device may also include a heat exchanger positioned over the heating chamber and a downcomer coupled between an outlet of the heat exchanger and a bottom of the heating chamber.

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to fluid flow simulation devices. In particular, embodiments of the present disclosure relate to thermal fluid flow simulation devices and associated chambers and methods.

BACKGROUND

Thermal fluid flow or natural convection may be used to move a fluid through a system. For example, some nuclear systems may use thermal fluid circulation to move a cooling fluid or a liquid fuel through the system. Many systems that use thermal fluid circulation may operate at high temperatures and/or pressures. In some cases, such as nuclear systems, system failures may have expensive and sometimes dangerous results, such that testing and/or validation in less volatile systems may help to prevent system failures in more critical equipment. Therefore, flow simulation systems may be developed to simulate the changes in temperature and flow rates using lower temperature fluids and lower pressures. The simulation systems may be used to validate engineering models and/or software simulations.

SUMMARY

Embodiments of the disclosure may include a fluid flow simulation device. The device may include a heating chamber comprising one or more electrodes and a conductive fluid. The device may further include a heat exchanger positioned over the heating chamber. The device may also include a downcomer coupled between an outlet of the heat exchanger and a bottom of the heating chamber.

Other embodiments of the disclosure may include a fluid heating chamber. The chamber may include a salt water solution comprising a salt concentration of at least 25 wt %. The chamber may further include one or more electrodes positioned within the fluid heating chamber, the one or more electrodes configured to induce a current through the salt water solution to heat the salt water solution.

Other embodiments of the disclosure may include a method of simulating fluid flow. The method may include heating a conductive fluid in a heating chamber by generating a current through the conductive fluid with one or more electrodes. The method may further include allowing the heated conductive fluid to rise through the heating chamber. The method may also include removing heat from the conductive fluid with a heat exchanger positioned above the heating chamber. The method may further include allowing the cooled conductive fluid to travel downward in an outer fluid passage outside the heating chamber.

DETAILED DESCRIPTION

The illustrations presented herein are not meant to be actual views of any particular fluid flow simulation device or component thereof, but are merely idealized representations employed to describe illustrative embodiments. The drawings are not necessarily to scale.

As used herein, the term “substantially” in reference to a given parameter means and includes to a degree that one skilled in the art would understand that the given parameter, property, or condition is met with a small degree of variance, such as within acceptable manufacturing tolerances. For example, a parameter that is substantially met may be at least about 90% met, at least about 95% met, at least about 99% met, or even at least about 100% met.

As used herein, relational terms, such as “first,” “second,” “top,” “bottom,” etc., are generally used for clarity and convenience in understanding the disclosure and accompanying drawings and do not connote or depend on any specific preference, orientation, or order, except where the context clearly indicates otherwise.

As used herein, the term “and/or” means and includes any and all combinations of one or more of the associated listed items.

As used herein, the terms “vertical” and “lateral” refer to the orientations as depicted in the figures.

As used herein, the terms “fluid flow simulation device” refer to a device configured to initiate fluid flow in a system in a non-hostile environment, such as an environment having low temperatures, low pressures, low radiation, low reactivity, etc., to simulate fluid flow in a hostile environment, such as fluid flow through a nuclear reactor, fluid flow generated by the heating of nuclear fuel within a reactor, etc.

As described above, fluid flow simulation devices may be used to simulate fluid flow through a system at lower temperatures and pressures than the final system. For example, nuclear energy production devices may generate substantial amounts of radiation and heat, requiring significant amounts of shielding. Furthermore, any sensors in or around the nuclear energy production devices would need to be designed to withstand the heat and radiation. Testing fluid flow in a system may require significant numbers of sensors and access to the system. Therefore, it may not be safe to use nuclear energy production devices in the early stages of testing due at least to the limited accessibility and specialized sensors. Furthermore, nuclear energy production devices may require advanced materials, which may increase the cost of building the reactors.

A simulation device that can generate similar temperature differentials in a fluid without the use of expensive materials, high temperatures, and radiation may enable fluid flow models to be validated at a lower cost and in safer conditions. Furthermore, the ability to observe the fluid flow without needing to remove shielding may enable higher levels of validation beyond sensor validation.

Many simulation devices utilize heating elements within the fluid to generate the temperature differentials of the fluid to simulate the fluid flow. The heating elements may heat the fluid by transferring heat from the heating element to the fluid. However, in a liquid fuel nuclear system, the fluid is not heated by a heating element, such as a fuel rod, rather, the liquid fuel is heated through nuclear reactions within the fluid. Therefore, to provide a more accurate simulation of the fluid flow within a liquid fuel nuclear reactor the simulation fluid may be heated by exciting electrons within the fluid without heat transfer from a separate heating element.

FIG.1illustrates a simulation device100. The simulation device100may be configured to simulate a molten salt nuclear battery having a substantially tubular design, such as the molten salt nuclear battery described in the U.S. Provisional Patent Application 63/261,775 titled LIQUID FUEL NUCLEAR POWER GENERATION DEVICES AND ASSOCIATED COMPONENTS AND SYSTEMS, filed Sep. 28, 2021, and the U.S. Patent Application titled LIQUID FUEL NUCLEAR POWER GENERATION DEVICES AND ASSOCIATED SYSTEMS AND METHODS, attorney docket number 2939-P16402.1US, filed on even date herewith, the disclosure of each of which are incorporated herein in their entirety by this reference.

The simulation device100may be configured to have similar geometry to the device being simulated. For example, the geometry of the simulation device100may be dimensionally the same as the device being simulated. In some embodiments, the geometry of the simulation device may be proportionally the same as the device being simulated. For example, a height to diameter ratio of the simulation device100may be substantially the same as the device being simulated, such that a shorter simulation device100may have a smaller diameter as well. In other embodiments, a critical dimension may be determined such that the critical dimension of the simulation device100and the device being simulated may be substantially the same, with the other dimensions being approximated in a manner that may reduce cost or facilitate easier construction and/or workability. For example, if the height is determined to be a critical dimension and the diameter is determined to be less critical to performance, the simulation device100may be constructed to substantially match a height of the device being simulated and a diameter of the simulation device100may be constructed to diameters available in off-the-shelf materials, such that the cost of procuring parts for the simulation device100may be reduced. The geometry of the simulation device100may minimize the pressure drop, enabling natural circulation within the simulation device100.

As illustrated inFIG.1, the simulation device100may include a case102extending between two end caps104. The case102may have a substantially tubular structure. For example, the case102may be a substantially cylindrical tube as illustrated inFIG.1. In other embodiments, the case102may have other tubular geometries, such as a rectangular tube, a triangular tube, etc. The end caps104may have a complementary geometry configured to enclose the inner portion of the case102. For example, the end caps104may have substantially the same shape as a cross-section of the case102, with a larger major dimension (e.g., diameter, width, apothem, radius, etc.). The case102may also include flanges106on the ends of the case102configured to create a mounting point between the case102and the end caps104. The flanges106may include interfacing elements, such as interfacing hardware, such as studs or pins and/or interfacing geometry, such as holes, threaded inserts, threaded holes, etc.

FIG.2illustrates a cross-section view of the simulation device100. The case102may be a hollow tube housing multiple additional nested tubes to create a tube within a tube structure. In some embodiments, one or more of the case102and the nested tubes may be formed from a substantially transparent material, such that the fluid flow within the different portions of the simulation device100may be visually observed. In other embodiments, the nested tubes may include windows. The different portions of the simulation device100may also include one or more sensors, such as temperature sensors, thermocouples, pressure sensors, flow sensors, strain sensors, etc., configured to measure properties of the fluid within the simulation device100and/or properties of the structure of the simulation device100.

The simulation device100may include a heating chamber204positioned near a center of the case102. The heating chamber204may be a tubular structure having a cross-section that is substantially similar to a cross-section of the case102with a smaller major dimension. The heating chamber204may have the smallest major dimension of the nested tubes, such that the heating chamber204may be the innermost of the nested tubes. The heating chamber204may include a fluid inlet206near a bottom portion of the heating chamber204and a fluid outlet208near a top portion of the heating chamber204. The heating chamber204may also include one or more electrodes210positioned within the heating chamber204.

The electrodes210may be configured to generate or induce a current through a fluid within the heating chamber204by creating a voltage differential across the fluid, such as between two electrodes210. The simulation fluid (e.g., working fluid) of the simulation device100may be a conductive fluid (e.g., an ionized fluid capable of carrying a current), such as a salt water solution. In some embodiments, the simulation fluid may be a salt water solution having a salt content (e.g., salt concentration) of greater than about 1 wt %, and a maximum concentration of the salt saturation conditions for the operating conditions of the unit, i.e., temperature and pressure, or other suitable conducting fluid. For example, the salt concentration may be less than about 25 wt %, such as between about 1 wt % and about 25 wt %. The salt content may enable the electrodes210to generate a current through the simulation fluid. Higher salt contents may reduce the voltage that is used to generate the current. The simulation fluid may be enclosed within the case102and configured to pass through the heating chamber204. The current passing through the simulation fluid may cause the simulation fluid to increase in temperature. Heating the simulation fluid by passing a current through the fluid may substantially mimic the fluid behavior of a nuclear molten salt solution, such as a solutions of fluorine and uranium, fluorine and thorium, chlorine and uranium, chlorine and thorium, etc. Nuclear reactions within the nuclear molten salt solution may internally heat the nuclear molten salt solution similar to the internal heat generated by passing a current through the simulation fluid.

A substantially accurate simulation may be created by substantially matching a volumetric energy generation rate (e.g., the amount of heat generated in the fluid per volume of the fluid). For example, a simulation device100configured to simulate a molten salt nuclear reactor may be configured to generate heat within the simulation fluid at a rate of between about 0.5 Megawatts/meter3 (MW/m3) and about 3 MW/m3, such as about 1 MW/m3. The volumetric energy generation rate may be controlled by adjusting the voltage provided to the one or more electrodes210and/or by changing the number of active electrodes210within the heating chamber204. For example, increasing a voltage provided to the active electrodes210may increase the energy generation rate. Increasing the number of active electrodes210within the heating chamber204may also increase the energy generation rate without increasing the voltage.

As the simulation fluid is heated within the heating chamber204, an upward flow may be created as the warmer fluid rises in the heating chamber204. The upward flow may be characterized as natural convection. The upward flow may be driven by a temperature difference between the fluid entering the heating chamber204through the fluid inlets206and the fluid exiting the heating chamber204through the fluid outlets208. The heating chamber204may be configured to achieve a temperature difference of between about 1° C. and about 100° C., such as between about 5° C. and about 50° C. The flow velocity of the fluid through the heating chamber204may affect the temperature differential. The difference between the flow velocities may affect the amount of time that the fluid spends in the heating chamber204. For example, a high flow velocity may be in the heating chamber204for a shorter amount of time such that the fluid may not absorb as much energy as a slower moving fluid. The reduction in energy imparted to the fluid may result in a lower temperature differential than the slower moving fluid. This may also be similar to a molten salt nuclear reactor, where a higher flow rate through the reactor may result in fewer reactions and a lower temperature differential. The simulation device100may be configured to measure a temperature differential between the fluid inlets206and the fluid outlets208. The simulation device100may be configured to compare the measured temperature differential to a temperature differential threshold and adjust the voltage applied to the electrodes210to change the temperature differential. The temperature differential threshold may be determined based on an expected or desired temperature differential for the nuclear reactor being simulated. The simulation fluid may rise within the heating chamber204until it reaches an upper portion of the heating chamber204, where the simulation fluid may exit the heating chamber204through fluid outlets208in the heating chamber204. The fluid outlets208may be openings or passages formed in the wall of the heating chamber204. The fluid outlets208may be arranged radially about the top portion of the heating chamber204, such that the simulation fluid may exit the heating chamber204in substantially all radial directions.

The upper portion of the heating chamber204may be surrounded by a heat exchanger212. The heat exchanger212may include multiple coils configured to extract heat from the simulation fluid as described in further detail below. The simulation fluid may exit the heating chamber204and pass through the heat exchanger212. As the simulation fluid passes through the heat exchanger212the simulation fluid may be cooled. The cooled simulation fluid may begin to travel downward again through natural convection.

The simulation device100may include an inner case202positioned between the case102and the heating chamber204. The inner case202may be configured to define a fluid passage214(e.g., downcomer) between the inner case202and the case102. The simulation fluid may travel through the fluid passage214to a bottom portion of the simulation device100after being cooled in the heat exchanger212. In some embodiments, the fluid passage214may be one or more tubes coupled between the heat exchanger212and the bottom of the simulation device100. The inner case202may also define an insulated space216between the fluid passage214and the heating chamber204. The insulated space216may be configured to substantially limit the transfer of heat from the heating chamber204to the simulation fluid traveling through the fluid passage214. In some embodiments, the insulated space216may be an air gap between the inner case202and the heating chamber204. In other embodiments, the insulated space216may be filled with an insulating material, such as foam, fiberglass, etc.

When the simulation fluid reaches the bottom portion of the simulation device100, the fluid may re-enter the heating chamber204through fluid inlets206positioned in a bottom portion of the heating chamber204. The fluid inlets206may be openings or passages formed in the wall of the heating chamber204. The fluid inlets206may be arranged radially about the bottom portion of the heating chamber204, such that the simulation fluid may enter the heating chamber204from substantially all radial directions.

FIG.3andFIG.4illustrate views of the upper portion of the simulation device100. As described above, the heated simulation fluid may exit the heating chamber204through fluid outlets208positioned radially about the heating chamber204. The fluid may then pass through the heat exchanger212. The heat exchanger212may include one or more rows of tubes304. For example, the heat exchanger212may include a first row of tubes304a, a second row of tubes304b, and a third row of tubes304c. Each row of tubes304may be formed from one or more tubes306formed into a coil substantially surrounding the heating chamber204. The one or more tubes306may be filled with a cooling fluid, such as water or refrigerant. The cooling fluid may flow through the one or more tubes306removing heat from the one or more tubes306. The cooling fluid may then be cooled through a separate heat removal device, such as a fin tube heat exchanger, a plate heat exchanger, a chiller, a refrigeration loop, etc.

The tubes306in each row of tubes304may be spaced such that the simulation fluid may pass between the tubes306. If the heat exchanger212includes multiple rows of tubes304as illustrated inFIG.3andFIG.4, the rows of tubes304may also be spaced, such that the simulation fluid may pass between the rows of tubes304. The rows of tubes304may have different numbers of coils. For example, the first row of tubes304amay include a larger number of coils of tubes306than the second row of tubes304bor the third row of tubes304c. The number of coils of tubes306may reduce as the row of tubes304gets farther from the heating chamber204. For example, as the simulation fluid travels a greater distance from the heating chamber204through the heat exchanger212the amount of heat to be removed from the simulation fluid may be reduced at least due to the amount of heat that the rows of tubes304positioned nearer to the heating chamber204have already removed. Furthermore, the first row of tubes304amay also be configured to remove additional heat that may be transferred from the heating chamber204to the simulation fluid through the insulated space216and the inner case202, at least in the upper region of the heating chamber204where the temperatures in the heating chamber204may be the highest.

The simulation device100may include a second inner case302in the area of the fluid passage214below the heat exchanger212. The second inner case302may define an additional insulated space308between the inner case202and the fluid passage214. The additional insulated space308may further limit heat transfer from the204to the fluid passage214.

FIG.5andFIG.6illustrate views of the lower portion of the simulation device100. As described above, the simulation fluid may travel through the fluid passage214to the lower portion of the simulation device100. The end cap104on the bottom end of the case102may stop the downward flow of the simulation fluid. The simulation fluid may then flow through the fluid inlets206back into the heating chamber204. The heating chamber204may include an orifice plate602. The orifice plate602may include one or more orifices604in the orifice plate602through which the simulation fluid may pass. The orifice plate602may be configured to control the flow of the simulation fluid through the heating chamber204. For example, the orifice plate602may be configured to substantially prevent turbulent flow and/or the formation of vortices in the heating chamber204. In some embodiments, the orifice plate602may be configured to regulate the flow velocity of the simulation fluid. In some embodiments, the orifice plate602may be adjustable, such as to change the flow velocity between simulations or mid simulation.

FIGS.7A and7Billustrate different views of an electrode arrangement in the heating chamber204of the simulation device100.FIG.7Aillustrates a cross-sectional view of the heating chamber204.FIG.7Billustrates a schematic side view of the heating chamber204. The heating chamber204may include multiple electrodes210spaced throughout the heating chamber204to generate heat in the simulation fluid.

The electrodes210may be arranged in electrode sets702,704,714. Each electrode set702,704,714may include multiple electrodes210angularly spaced about the heating chamber204.FIG.7Aillustrates two electrode sets702,704. The first electrode set702may include at least two electrodes210, such as three electrodes210, as illustrated inFIG.7A. In other embodiments, the first electrode set702may include a different number of electrodes210, such as two electrodes210, four electrodes210, or greater than four electrodes210. The electrodes210of the first electrode set702may be arranged with substantially uniform angular spacing. For example, an angle708between two adjacent electrodes210of the first electrode set702may be about 120° when the first electrode set702includes three electrodes210as illustrated inFIG.7A. In an embodiment, with four electrodes210, the angle708between two adjacent electrodes210may be about 90°.

A second electrode set704may be positioned a distance away from the first electrode set702. The second electrode set704may be spaced both vertically and angularly from the first electrode set702. For example, as illustrated inFIG.7A, the second electrode set704may include a similar arrangement of electrodes210(e.g., similar number of electrodes210and a similar spacing between electrodes210). The second electrode set704may however, be angularly offset from the first electrode set702by an angle706. For example, the angle706may be less than the angle708between individual electrodes210of the first electrode set702, such that the electrodes210of the second electrode set704may be positioned angularly between the electrodes210of the first electrode set702. In some embodiments, the angle706may be about one half of the angle708, such that the electrodes210of the second electrode set704may be positioned to bisect the angle708between the electrodes210of the first electrode set702.

The second electrode set704may also be spaced vertically from the first electrode set702as illustrated inFIG.7B. The vertical spacing between each of the first electrode set702, the second electrode set704, and the third electrode set714may distribute electrical current throughout the heating chamber204generating greater amounts of heat in the simulation fluid within the heating chamber204. The vertical positions of the electrode sets702,704,714may be determined to approximate the releases of energy in a nuclear reactor. For example, models of a core of a nuclear reactor may predict zones that are hotter than other zones (e.g., having a larger number of reactions), such as due to delayed release neutrons. The electrode sets702,704,714may be positioned to approximate the vertically locations of the hotter zones.

Each electrode set702,704,714may include two sets of electrodes210, a primary electrode set716and a secondary electrode set718. The primary electrode set716may be a set of source electrodes210coupled to a positive side of the power source and the secondary electrode set718may be a set of receiving electrode210coupled to a negative side of the power source. The primary electrode set716and the secondary electrode set718may be configured to generate a current between the primary electrode set716and the secondary electrode set718through the simulation fluid. The primary electrode set716and the secondary electrode set718may be spaced vertically in the heating chamber204as illustrated inFIG.7B. The vertical spacing between the primary electrode set716and the secondary electrode set718may be configured to provide substantial space for the current between the primary electrode set716and the secondary electrode set718to generate heat within the simulation fluid while being sufficiently close together that the current may be generated with an easily accessible voltage, such as line voltage (e.g., 120 V, 220 V, 277 V, 408 V, etc.). The vertical spacing may be determined based on factors such as the available voltage, the composition of the simulation fluid, safety considerations, etc.

In some embodiments, the individual electrode sets702,704,714may include electrodes210having different lengths. For example, the first electrode set702may have electrodes210with a first length710and the second electrode set704may have electrodes210with a second length712as illustrated inFIG.7A. The different lengths710,712may generate heat in different portions of the simulation fluid. For example, the electrodes210of the first electrode set702may have a first length710that is greater than the second length712of the electrodes210in the second electrode set704. The greater first length710of the electrodes210in the first electrode set702may generate a current in a portion of the simulation fluid radially closer to a center of the heating chamber204than the electrodes210of the second electrode set704. This may result in a more uniform heat distribution throughout the simulation fluid in the heating chamber204.

The embodiments of the present disclosure may provide a less expensive simulation device for simulating natural convection flow within a liquid fuel nuclear reactor. Embodiments of the present disclosure may be configured to simulate the generation of heat within a liquid rather than the transfer of heat to a liquid. This may provide a more accurate representation of a liquid fuel nuclear reactor. The cost of the simulation device may be substantially lower than the cost of building a liquid fuel nuclear reactor. Furthermore, embodiments of the present disclosure may not include moving components, such as pumps, valves, compressors, etc., such that the embodiments of the present disclosure may be less complicated and have higher efficiencies. The lower costs of building and/or operating the simulation devices may enable greater amounts of testing and/or validation of the far more expensive nuclear reactors, which may ultimately reduce the cost of producing a fully functional liquid fuel nuclear reactor.

The embodiments of the disclosure described above and illustrated in the accompanying drawing figures do not limit the scope of the invention, since these embodiments are merely examples of embodiments of the invention, which is defined by the appended claims and their legal equivalents. Any equivalent embodiments are intended to be within the scope of this disclosure. Indeed, various modifications of the present disclosure, in addition to those shown and described herein, such as alternative useful combinations of the elements described, may become apparent to those skilled in the art from the description. Such modifications and embodiments are also intended to fall within the scope of the appended claims and their legal equivalents.