Direct thermal energy storage (TES) systems and methods for making and using them

Abstract

In alternative embodiments, TES systems as provided herein comprise two primary components: a sealed container for encasing Phase Change Materials (PCMs) (PCMs are substances that can absorb and release heat energy when they change state, which can be used in HVAC systems for heating and cooling; PCMs can help save energy and improve thermal comfort in buildings); and, a rack for hanging these containers mounted at the top of a duct beneath the rooftop unit (RTU) on a rooftop (RTUs are typically self-contained heating and cooling units that are mounted on the roof of a building or structure).

Description

[0001] PATENT 6803*159914PCT DIRECT THERMAL ENERGY STORAGE (TES) SYSTEMS AND METHODS FOR MAKING AND USING THEM RELATED APPLICATIONS

[0002] This Patent Convention Treaty (PCT) International Application claims the benefit of priority under 35 U.S.C. § 119(e) of U.S. Provisional Application Serial No. (USSN) 63 / 756,558, February 10, 2025. The aforementioned application is expressly incorporated herein by reference in its entirety and for all purposes. All publications, patents, patent applications cited herein are hereby expressly incorporated by reference for all purposes.

[0003] TECHNICAL FIELD

[0004] This invention generally relates to heating, ventilation, and air conditioning (HVAC) systems, and direct thermal energy storage (TES) systems. In alternative embodiments, TES systems as provided herein comprise two primary components: a sealed container for encasing Phase Change Materials (PCMs) (PCMs are substances that can absorb and release heat energy when they change state, which can be used in HVAC systems for heating and cooling; PCMs can help save energy and improve thermal comfort in buildings); and, a rack for hanging these containers mounted at the top of a duct beneath the rooftop unit (RTU) on a rooftop (RTUs are typically self-contained heating and cooling units that are mounted on the roof of a building or structure).

[0005] BACKGROUND

[0006] One of the largest contributors to building energy use is building heating and cooling, and this causes large diurnal swings in energy consumption. In a warm region, energy use will peak during the late afternoons in summer, when buildings run air conditioning compressors at full power. The electrical grids must design their generation, transmission, and distribution capacity around this peak summer load.

[0007] There are substantial economic incentives to shifting energy from afternoon to morning, to free up grid capacity. A commonly suggested solution is to install electrochemical batteries behind the meter at buildings, where they will charge in the morning and power the air conditioner in the afternoon. However, small scale battery installation is expensive, thanks to the high cost of the cells, installation, electrical panel upgrades, and fire suppression requirements. In many regions, code prohibits the use of lithium-ion chemistry in small buildings because of fire risk.PATENT 6803*159914PCT An alternative to the installation of electrochemical storage is direct thermal energy storage (TES), which will specifically address the heating and cooling needs of a building. One example of a thermal storage system is to install a phase change material in a building’s HVAC ductwork. The phase change material is frozen in the morning when the air conditioning is turned on at the beginning of building occupancy and thawed in the afternoon by passing unconditioned air over it. In this way, energy use is shifted from afternoon to morning, thus, the peak energy consumption of a building is reduced.

[0008] However, existing TES designs have limitations, for example, they must be installed in-line in the HVAC duct. This is not a significant issue for new construction, but for retrofit applications it will require that existing furniture and the drop ceiling around the work area be removed; the drop ceiling below the duct at least partially removed; and a TES weighing tens to hundreds of kilograms be hoisted to be bolted to the solid ceiling such that it is aligned to the ducting. The total cost of such a retrofit installation varies considerably by building, but in some cases exceed the cost of the hardware itself. While the installed cost of such a TES is still less than batteries, and the useful lifetime greater than batteries, the payback period can be 5 to 10 years, which is longer than affordable or desirable.

[0009] Therefore, there is a great need and demand to identify new designs for TES which will have a faster payback period thanks to lower first costs for capital and installation.

[0010] SUMMARY

[0011] In alternative embodiments, provided are direct thermal energy storage (TES) systems and products of manufacture and structures comprising direct thermal energy storage (TES) systems as provided herein.

[0012] In alternative embodiments, provided are hermetically sealed (or air-tight, or liquid impermeable) packages or containers comprising at least one phase change material (PCM), wherein the hermetically sealed package or containers comprises a PCM disposed (or contained) in a plurality of metal tubes, wherein optionally each of the PCM-comprising plurality of metal tubes is sealed under a vacuum.

[0013] In alternative embodiments of the hermetically sealed package or container: the plurality of PCM-comprising metal tubes comprise or are fabricated from aluminum or an Al alloy or stainless steel;PATENT 6803*159914PCT the volume of the tube is more than about 50% filled with the PCM, or the volume of the tube is filled with PCM to within about 50%, 60%, 70%, 80% or 90% or more (or between about 45% to 99%) of the pipe’s capacity before sealing;

[0014] - the contents of the tube further comprise a thermally conductive material, and optionally the thermally conductive material comprises a metal mesh or metal flake;

[0015] - the contents of the plurality of tubes further comprise a magnetic ball or a plurality of magnetic balls, and optionally the magnetic ball is a hollow stainless steel ball, or the magnetic ball comprises a permanent magnet embedded in a low density polymer, and optionally the polymer comprises a cross-linked silicone;

[0016] - the hermetically sealed package or container further comprises a magnetometer disposed outside the tube, wherein the magnetometer is used to detect the level of the magnetic ball within the tube; and / or

[0017] - the hermetically sealed package or container comprising the plurality of tubes is hermetically sealed using a process comprising tungsten inert gas welding (TIG) welding, laser welding, ultrasonic welding, metal Inert Gas (MIG) welding, shielded metal arc welding (SMAW), flux-cored arc welding (FC AW), plasma arc welding (PAW) or any combination thereof; and / or the plurality of tubes is hermetically comprising PCM contained within are sealed using a process comprising tungsten inert gas welding (TIG), laser welding, ultrasonic welding, metal Inert Gas (MIG) welding, shielded metal arc welding (SMAW), flux-cored arc welding (FCAW), plasma arc welding (PAW) or any combination thereof.

[0018] In alternative embodiments provided are systems for thermal management in a building or HVAC system, comprising a plurality of hermetically sealed packages or containers comprising phase change material (PCM) hermetically sealed in a plurality of tubes or tubular structures, wherein the hermetically sealed packages or containers comprising the plurality of tubes or tubular structures are disposed or fabricated in a ductwork or plenum, and optionally the hermetically sealed packages or containers and the plurality of tubes are disposed or fabricated, or secured, immediately below, or substantially close to and below, a rooftop unit (RTU) air conditioner or heater or HVAC.

[0019] In alternative embodiments provided are systems for thermal management in a building or an HVAC system, comprising a plurality of hermetically sealed packages as provided herein.PATENT 6803*159914PCT In alternative embodiments of systems for thermal management in a building orHVAC system:

[0020] - the thermal management in a building or HVAC system comprise a frame disposed underneath or attached below a rooftop air conditioner or a rooftop unit (RTU) or HVAC, wherein the hermetically sealed packages comprising tubes comprising phase change material are affixed to the frame;

[0021] - the frame is physically affixed to a curb underneath the rooftop unit (RTU); - the hermetically sealed (or air-tight, or liquid impermeable) packages are separated by an anchor affixed to each end of the hermetically sealed package away from the frame; and / or

[0022] - the thermal management in a building or HVAC system further comprise at least one turbulence-inducing element, and optionally the at least one turbulenceinducing element is or is fabricated a turbulator, and optionally the at least one turbulence-inducing element is or is fabricated as a winglet.

[0023] In alternative embodiments, provided are HVAC systems comprising or having fabricated therein a system for thermal management as provided herein, or a plurality of hermetically sealed packages or containers as provided herein.

[0024] In alternative embodiments, provided are a building, a shed, a ship, a train, a tunnel, an automobile, an airplane or a boat comprising or having fabricated therein an HVAC system as provided herein, or a system for thermal management as provided herein, or a plurality of hermetically sealed packages or containers as provided herein.

[0025] In alternative embodiments, provided are use of an HVAC system to thermally regulate a building, a shed, a ship, a train, a tunnel, an automobile, an airplane or a boat, wherein the HVAC systems comprises or has fabricated therein a system for thermal management as provided herein, or a plurality of hermetically sealed packages or containers as provided herein.

[0026] The details of one or more exemplary embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.

[0027] All publications, patents, patent applications, American Type Culture Collection (ATCC) deposits and NCBI reference sequences cited herein are herebyPATENT 6803*159914PCT expressly incorporated by reference in their entireties for all purposes.

[0028] DESCRIPTION OF DRAWINGS

[0029] The drawings set forth herein are illustrative of exemplary embodiments provided herein and are not meant to limit the scope of the invention as encompassed by the claims.

[0030] FIG. 1 illustrates an exemplary process for manufacturing exemplary tubes used with PCM, where the process incorporates a structural configuration as used in processes used for filling heat pipes, as described in further detail, below.

[0031] FIG. 2 illustrates alternative embodiments of the shape of a heat pipe used in exemplary TES systems as provided herein, and how the shape of a heat pipe as used herein varies and may include (but are not limited to) flat rectangular, rounded rectangular, ovoid, and circular cross-sections.

[0032] FIG. 3 illustrates alternative embodiments of how vortex generators to the external surface of containers are used; and vortex generators as provided herein can comprise structures such as delta wings, delta winglets, rectangular wings, and rectangular winglets.

[0033] FIG. 4 illustrates an alternative embodiment of an exemplary framing element that is made of parallel or crossed metal wires.

[0034] FIG. 5 illustrates an alternative embodiment of how tubes are anchored by joining the bottom end of individual tubes as they are assembled; in this embodiment exemplary tubes are capped at the bottom by a plastic molded end cap, and the cap contains magnets to snap each tube to affix to the next.

[0035] Like reference symbols in the various drawings indicate like elements.

[0036] DETAILED DESCRIPTION

[0037] In alternative embodiments, provided are direct thermal energy storage (TES) systems and products of manufacture and structures comprising direct thermal energy storage (TES) systems as provided herein. In alternative embodiments, provided are TES designs that can be installed as a retrofit to an existing building by a single contractor, without the use of a hoist, and / or without disrupting the interior furnishings or ceiling.

[0038] In alternative embodiments, TES systems as provided herein comprise two primary components:PATENT 6803*159914PCT • a sealed container for encasing Phase Change Materials (PCMs) (PCMs are substances that can absorb and release heat energy when they change state, which can be used in HVAC systems for heating and cooling; PCMs can help save energy and improve thermal comfort in buildings)

[0039] • a rack for hanging these containers mounted at the top of a duct beneath the rooftop unit (RTU) on a rooftop (RTUs are typically self-contained heating and cooling units that are mounted on the roof of a building or structure).

[0040] The PCM-comprising sealed containers are fed or otherwise inserted into the duct beneath the RTU on the rooftop, and then hung on a mounting rack such that they are suspended vertically (or substantially vertically) below the duct, but above a main trunk line that comes out of a plenum (a plenum in HVAC systems is a box or any volume in a building structure that connects to the HVAC system; it has a critical function: to bring in, distribute, or remove air. Each HVAC system typically uses two plenum boxes: a supply plenum and a return plenum: a supply plenum works by taking in the new cool or warm air from the heater or air conditioning system and, in turn, distributes it throughout the building using the HVAC’s ductwork; a return plenum takes in that used room air and, using the ductwork sends it back to the core HVAC system and that air is filtered, cooled, and returned to the space).

[0041] Sealed containers

[0042] In alternative embodiments, a sealed container used in a TES system as provided herein comprises a clamshell Phase Change Materials (PCM) plate, including those as described in U.S. patent no. (USPN) 10,955,154; U.S. patent application no. US / 2024 / 0125493 Al; WO / 2025 / 015175. Such clamshell plates will work for installation underneath an RTU, using the systems and methods described herein.

[0043] In alternative embodiments, the PCM is sealed within a metal tube, alternatively fabricated from aluminum (Al) or Al alloy. Use of a metal (such as an Al) metal tube provides (but is not limited to) four advantages:

[0044] (1) PCM-filled tubes are smaller and therefore lighter than plates, and easier to handle, align, and install;

[0045] (2) the PCM-filled tubes have fewer edges, and are less susceptible to damage and less likely to cut the installing contractor and the building’s internalPATENT 6803*159914PCT insulation (which in turn avoids introducing insulation particles to airstream / occupied space);

[0046] (3) as will be described below, exemplary PCM-filled tubes can be designed to fully occupy the significant depth of the ductwork below the RTU without a large pressure drop, providing enhanced thermal storage energy per unit volume; and / or

[0047] (4) the PCM-filled tubes can easily be sealed under vacuum, which makes them more robust to exposure to thermal excursions seen in a fire, and therefore have greater fire safety potential than PCM systems not sealed under vacuum. In alternative embodiments, to construct sealed tubes, an exemplary process comprises one or more of the following steps:

[0048] o an open metal (aluminum or Al alloy) tube is cleaned to remove internal residue;

[0049] o the tube is crimped and welded or capped and welded at one end; o at a second end, the tube is either welded closed with a cap that contains a small charging port, or left open to be directly charged; o PCM is charged into the tube opening or charging port; and / or o the tube is evacuated before pinching / sealing the charging port and / or the second end; and

[0050] o the system is checked for leaks.

[0051] In alternative embodiments, this exemplary process for manufacturing these tubes with PCM can incorporate a structural configuration as used in processes used for filling heat pipes, as described for example in Edelstein, F. Heat pipe manufacturing study . No. NASA-CR-139140. 1974; and an image from that reference is shown in FIG. 1, which illustrates an exemplary configuration of a PCM filling station; noting that Edelstein charged the tubes with low-pressure fluids (in Edelson, the aluminum heat pipes have been previously filled with relatively volatile liquids such as water, acetone, toluene, or ammonia, and the volatility of these gases is critical to their functioning as a heat pump).

[0052] In TES systems as provided herein, the working fluid comprise at least one PCM, such for example, as a bio-derived wax or paraffin (for example, paraffin pellets as described by USPN 9,315,710 B2). Paraffin waxes that can be used are mixtures of saturated n- and iso- alkanes, naphthenes, and alkyl- and naphthene-PATENT 6803*159914PCT substituted aromatic compounds; for example, an alkane paraffin wax chemical composition comprises hydrocarbons with the general formula CnH2n+2, such as hentriacontane, C31H64.

[0053] Unlike the traditional working fluids used in a heat pipe, a PCM is not volatile at or near room temperature. Whereas a traditional heat pipe fluid is designed to change phases from liquid to gas near the system working temperature, where the movement of the gas rapidly transfers heat through space, from one side of the heat pipe to the other. By contrast, the PCMs described herein are designed to change from solid to liquid, and are not intended to transfer heat rapidly across space. Instead, PCM-filled tubes as provided herein are designed to store heat (or cool) at one time, and release it at a second time. Thus, function of the PCM-comprising tubes as provided herein differs from heat pipes. The containers produced for TES systems as provided herein are not suitable for use as conventional heat pipes, or for conventional spatial heat transfer applications. However, they are especially useful for thermal energy storage (TES) systems, and advantageously take advantage of existing manufacturing infrastructure for heat pipes to lower their practical cost.

[0054] In alternative embodiments, a PCM as provided herein is charged as a liquid, and the heat pipe is filled to 50%, 60%, 70%, 80% or 90% or more (or between about 45% to 99%) of the pipe’s capacity before sealing. This is different from the filling strategy for a liquid / gas heat pipe, where fill levels are typically around 30%, so that vapor may transport heat from the liquid-filled side of the pipe to the gas-filled side of the pipe during operation.

[0055] In alternative embodiments, PCM containers used in TES systems as provided herein are evacuated prior to sealing: evacuation removes air internal to the pipe, and thus removes any stresses that might otherwise be placed by trapped air on the inner walls of the pipe during heating and cooling cycles, or in case of a building fire. In alternative embodiments PCM containers used in TES systems as provided herein are hermetically sealed and resistant to fire to meet Class A plenum fire safety ratings.

[0056] In alternative embodiments, PCMs used in TES systems as provided herein comprise, or are based on, or derived from, waxes, which are flammable, and hence necessitate storage in a robust, sealed container to survive such fire testing.

[0057] In alternative embodiments the shape of a heat pipe used in TES systems as provided herein varies and may include (but are not limited to) flat rectangular, rounded rectangular, ovoid, and circular cross-sections, see for example FIG. 2, whichPATENT 6803*159914PCT illustrates exemplary of shapes of heat pipe used in TES systems as provided.

[0058] Rectangular and ovoid cross-sections can be preferable in some systems because they offer greater surface area to volume ratios, which can be useful for improving the rate of heat transfer between air and PCM.

[0059] In some embodiments, one or more properties of a PCM pipe used in TES systems as provided herein can be modified by the inclusion (mixing in with the PCM) of one or more additives; for example, in alternative embodiments, before charging with PCM, a thermally conductive material such as a metal mesh or metal flakes may be inserted or charged within the pipe interior in order to facilitate heat transfer to / from the PCM. Alternatively, the pipe may be left empty before filling, so that only PCM occupies the pipe volume.

[0060] In alternative embodiments, an additive can be mixed with a PCM and / or disposed in the tank of a heat exchange apparatus described herein. In some embodiments, an additive comprises a thermal conductivity modulator. A thermal conductivity modulator, in some embodiments, increases the thermal conductivity of the PCM. In some embodiments, a thermal conductivity modulator comprises carbon, including graphitic carbon. In some embodiments, a thermal conductivity modulator comprises carbon black and / or carbon nanoparticles. Carbon nanoparticles, in some embodiments, comprise carbon nanotubes and / or fullerenes. In some embodiments, a thermal conductivity modulator comprises a graphitic matrix structure. In other embodiments, a thermal conductivity modulator comprises an ionic liquid. In some embodiments, a thermal conductivity modulator comprises a metal, including a pure metal or a combination, mixture, or alloy of metals. Any metal not inconsistent with the objectives of the present invention may be used. In some embodiments, a metal comprises a transition metal, such as silver or copper. In some embodiments, a metal comprises an element from Group 13 or Group 14 of the periodic table. In some embodiments, a metal comprises aluminum. In some embodiments, a thermal conductivity modulator comprises a metallic filler dispersed within a matrix formed by the PCM. In some embodiments, a thermal conductivity modulator comprises a metal matrix structure or cage-like structure, a metal tube, a metal plate, and / or metal shavings. Further, in some embodiments, a thermal conductivity modulator comprises a metal oxide. Any metal oxide not inconsistent with the objectives of the present invention may be used. In some embodiments, a metal oxide comprises a transition metal oxide. In some embodiments, a metal oxide comprises alumina.PATENT 6803*159914PCT In other embodiments, an additive comprises a nucleating agent. A nucleating agent, in some embodiments, can help avoid subcooling, particularly for PCMs comprising finely distributed phases, such as fatty alcohols, paraffinic alcohols, amines, and paraffins. Any nucleating agent not inconsistent with the objectives of the present invention may be used.

[0061] In alternative embodiments, the maximum diameter or thickness of a pipe used in TES systems as provided herein, along with any thermally conductive contents, will determine the rate at which the PCM can be frozen or thawed. In alternative embodiments a wide diameter or thickness is preferred for cost reasons, as it increases the volume relative to the surface area of the pipe, and therefore decreases the relative cost contribution of the pipe; a wide diameter may also preferred for handling reasons, as it leads to fewer pieces that must be assembled into the final product, as will be described below. A shallow diameter or thickness leads to improved thermal transfer. In alternative embodiments, maximum diameter (thickness) of the PCM-comprising tubes used in TES systems as provided herein is about 1.5 cm, or 0.6 inches, or between about 1 cm and 1 inch, or 0.5 cm and 2 inches, when no thermally conductive additive is used.

[0062] Exemplary ways to increase cooling power provided by PCM containers

[0063] In alternative embodiments, a metal mesh or similar conductive structure is inserted into a container alongside (or together with) the PCM; and when the mesh or similar conductive structure is inserted into the container alongside the PCM, power performance increases. In alternative embodiments, an aluminum mesh that occupies about 5 to 10% of the PCM volume is used, and this improves the power performance by about 5 to 10-fold. This would allow a tube that is limited to 1.5 cm diameter without thermally conductive additives or mesh, to be equivalent to a tube of about 10 cm with mesh. In alternative embodiments, a circular cross-section tube of length of about 1.5 meters with an internal diameter of about 1.5 cm is used, and this would have an internal volume of about 265 cc, and contain about 250g of PCM (assuming a density slightly higher than 0.9 g / cc). In alternative embodiments installation of a TES as provided herein in an HVAC requires about 50-100 kg of PCM, and therefore would require about 200-400 of these tubes, making installation relatively complex. To address this potential problem, in alternative embodiments, the thickness of the walls of an exemplary tube is between about 0.02 inch to about 0.25 inch, or is aboutPATENT 6803*159914PCT 0.03 inch, or 0.04 inch, or 0.05 inch, or 0.06 inch, where in some embodiments thinner walls are preferred to reduce the cost and weight of the aluminum, but thicker walls can provide better performance in fire testing. For the circular tube described above, the weight of the aluminum will likely match or exceed the weight of the PCM, more than doubling total system weight.

[0064] In alternative embodiments a mesh is used, and in alternative embodiments if a mesh is used the diameter of the tube is increased; for example, if a 10 cm diameter, 1.5 m long tube is used, its internal volume would be over 11 liters, and it would be charged with over 10 kg of PCM. In another embodiment having 0.05 inch walls, the tube would contribute another 1.6 kg in mass, and the total system weight will be about 11-12 kg (about 25 lbs).

[0065] In one preferred embodiment, each tube has a weight of between about 5 to 15 pounds (or 2 to 6 kg), between about 2 to 20 pounds, to facilitate installation, for example, using a single hand, while still limiting the number of pieces to 10-20 for the installation described above. Thus, in one alternative embodiment a tube diameter or thickness is between about 5 to 7 cm, is between about 3 to 10 cm. In alternative embodiments the tube need not have a round cross-section, and with an oval or rectangular cross-section the tube diameter could be decreased to increase power transfer, while keeping overall tube weight within the desired range, a set of trade-offs that would be understood by someone skilled in the art.

[0066] Improving heat transfer from the air

[0067] In some embodiments, the mixing of air around the tubes is increased in order to accelerate heat transfer; in alternative embodiments, this includes adding a piece on the exterior of the container to disrupt air flow, such as a turbulator or vortex generator. In alternative embodiments, vortex generators to the external surface of containers are used, and vortex generators such as those known in the art or as described by Chai, et al. "A review of air side heat transfer augmentation with vortex generators on heat transfer surface." Energies 11.10 (2018): 2737 can be used; and vortex generators as provided herein can comprise structures such as delta wings, delta winglets, rectangular wings, and rectangular winglets, as illustrated in FIG. 3. Addition of these vortex-generating elements will increase the pressure drop caused by the PCM containers, but when placed into a duct, extended tubes will create only a modest pressure drop when the flow of air is along the long axis of the tube. In somePATENT 6803*159914PCT embodiments, it is preferred to keep the pressure drop of the entire PCM assembly in an HVAC duct less than or equal to about 0.05 to 0.1” of water, or alternatively, between about 0.025 to 0.3” of water.

[0068] To create the desired turbulence, in an alternative embodiment, a plastic or metal element decorated with wings or winglets is affixed around each tube, either before or after filling. Alternatively, flat PCM-filled tubes may be placed in a staggered configuration alongside a separate turbulator, which mixes the air around it and thereby distributes turbulent air to each of the tubes. An example of such a turbulator is a HITRAN™ (hiTRAN) system (Calgavin, Warwickshire, UK) (which incorporate a wire matrix element, called turbulators, which provide benefit for laminar and transitional flow regimes). In alternative embodiments, a turbulator may be configured around the tubes. In alternative embodiments, an enhanced surface tube such as a VIPERTUBE™ (Bischofshofen, Austria) or a finned tube may be employed as the primary container for the PCM.

[0069] Heat from the air is exchanged with the PCM as passes over the containers in an assembly. During discharge, the upstream side of the PCM may thaw before the downstream side, which in some cases is disadvantageous, as the PCM assembly will present shorter and shorter lengths for heat transfer over the length of discharge. In alternative embodiments, to equalize the melting across the length of the container, a gradient of conductive filler can be used such that the upstream portions have higher conductivity than the downstream portions: for example, if the container is a tube, multiple sizes of metal flakes can be loaded in tube such that smaller flakes, which pack more densely, are at the bottom, while larger flakes, which pack less densely, are at the top. In alternative embodiments a similar gradient in the pitch or density of a metal mesh provides analogous results, ensuring that the upstream segment of the tubes (where the temperature gradient is largest) thaw more slowly than the downstream segments (where temperature gradients are smaller), and thereby more evenly thawing the PCM.

[0070] In another embodiment, the pitch of a turbulator or the density of vortex generators are set as a gradient, so that the creation of turbulence in the air is less severe on the upstream side, and more severe on the downstream side. Again, this will lead to less contact between air and PCM upstream, and more contact downstream, equalizing the rate of melting.PATENT 6803*159914PCT State of charge measurement inside a PCM container

[0071] In alternative embodiments, containers such as elongated or tubular containers used in TES systems as provided herein comprise use of a magnetic level sensor and a magnetometer is disposed outside the tube. In alternative embodiments, the magnetic level sensor comprises a magnetic ball, optionally a hollow stainless steel ball, or a magnetic ball is a permanent magnet embedded in a low density polymer (where optionally the polymer comprises a cross-linked silicone).

[0072] In some embodiments, it is preferred to include a method for measuring the state of charge of the PCM. In a fully charged PCM container used for shifting cooling, the PCM will be 100% solidified; when discharged, the PCM will be 0% solidified. During use, the PCM will be at an intermediate stage of melt / solid.

[0073] Because the temperature of the PCM does not change during the melting process, intermediate states of charge cannot be measured by measuring the temperature of the PCM alone.

[0074] The volume of the PCM does change significantly during solidification, for example compacting by 7-8% when transitioning from liquid to solid. Thus, the state of charge of the PCM can in principle be measured by measuring the volume of the material. However, such a measurement is difficult in an environment where PCM is sealed inside a metal container.

[0075] We have found that the challenge of measuring PCM volume by measuring its height is substantially reduced by using elongated or tubular containers, such that the level of the PCM can be tracked with good accuracy even with a small average density change to the bulk. In one embodiment, the state of charge is tracked using a magnetic level sensor. In one embodiment, a low-density magnetic ball is added to the tube prior to sealing. This magnetic ball is designed to have a density of less than that of the PCM, for example less than about 0.86 g / mL. In an alternative embodiment, the magnetic ball is a hollow stainless-steel ball. In another embodiment, the magnetic ball is a permanent magnet embedded in a low-density polymer such as a cross-linked silicone.

[0076] In these embodiments, a magnetometer is disposed outside the tube near the level of the surface on filling. In one embodiment, the tube is disposed at an angle with respect to the ground, such that one end of the tube is higher than the other, and the magnetic ball is at the top of the tube. In one embodiment, the magnetometer is calibrated. For example, the response of the magnetometer is measured when the tubePATENT 6803*159914PCT is fully discharged, at a temperature just above the melting point; and then the response of the magnetometer is measured when the tube is fully charged, at a temperature just below the melting point. In some embodiments, this calibration may be done at the factory. In some embodiments, this calibration is done in the field after the device is installed. In some embodiments, the calibration values are corrected to account for the coefficient of thermal expansion of the liquid above and below the melting point. After calibration, the state of charge is calculated based on interpolating the magnetometer signal between its values at full charge and discharge.

[0077] In another embodiment, TES systems as provided herein comprise an ultrasonic level sensor or an array of ultrasonic transducers, where the state of charge of the tube is measured using the ultrasonic level sensor. In one embodiment, an array of ultrasonic transducers is disposed on the outside of the tube, near the top level of the PCM within the tube. In some embodiments the level of the PCM is established by interpolating between the known heights during charge and discharge.

[0078] Assembling and installing containers underneath an RTU

[0079] In some embodiments, to optimize the air flow within the duct the containers are spaced at regular intervals; for example, an exemplary duct underneath a rooftop air conditioning unit (RTU) has a rectangular cross-section, such as 15”xl7”; it is thus favorable to arrange the containers in a regular pattern within that space. In some embodiments, for tubes, this may be, without being limiting, a 4 x 5 rectangular pattern (with 20 tubes), or a 5 x 7 pattern (35 tubes), or an 8 x 10 pattern (80 tubes) depending on the size of the tubes and the load-shift requirement of the building. In some embodiments, some of the locations for tubes in the above-described grid are replaced by turbulators to productively increase mixing. In another embodiment, a hexagonal grid may be used instead of a rectangular one.

[0080] In some embodiments, at the top of the duct, the set of hanging containers is affixed to framing element at the top of the tubes. In one embodiment, the framing element is a metal wire mesh or grate, and is secured to the roof curb using prefabricated bends on the edges of the framing element, or flat edges that mate to the edge where the roof curb attaches to the plenum to distribute the weight of the tubes to the curb. In some embodiments, the framing element is a perforated metal sheet, or a molded plastic end plate. In some embodiments, the framing element is made of parallel or crossed metal wires, as illustrated for example in FIG. 4. In somePATENT 6803*159914PCT embodiments, the framing element is cut to size on site, such that it matches the required dimensions of the exposed roof curb.

[0081] In alternative embodiments, the framing element has a low fill factor, for example 30% or below, or 20% or below, or 10% or below, or 5% or below, to allow air to flow past it with minimal pressure drop. In one embodiment, the framing element is a steel metal plate ’A” thick, capable of supporting the weight of an array of tubes (100-200 lbs in total) hanging from it, and distributing this weight to a roof curb. In alternative embodiments the framing element is secured to the roof curb underneath the RTU, for example using bolts or hooks also. In alternative embodiments the tubes are secured to the framing element for example through a series of hooks.

[0082] In some embodiments a set of anchors is used to ensure the tubes remain regularly separated along their lengths. For example, in alternative embodiments the tubes are fed through a second end plate to form a regular pattern. Aligning and affixing the tubes in this way also productively keeps them from independently swinging in the air duct, which could cause noise. These anchors would also contribute a low fill factor to ensure that pressure drops do not exceed their design target.

[0083] In an alternative embodiment, the tubes are anchored dynamically by joining the bottom end of individual tubes as they are assembled. In this example, tubes are capped at the bottom by a plastic molded end cap, and the cap contains magnets to snap each tube to affix to the next, for example, as illustrated in FIG. 5. With this solution, tubes can be inserted into a duct and removed as individual units, without the need to align to an external framing element. This is especially useful to align tubes that will be placed down into ductwork, where the ends of the tubes cannot be easily reached to correct misalignment.

[0084] In one embodiment, the framing element comprises square or rectangular openings through which the metal tube can be fed; and the metal tube contains endcaps with orienting magnets aligned roughly to the comers of the squares. The metal tube can be inserted in a configuration that allows the endcap to pass through the squares or rectangles, and then rotated such that the orienting magnets point towards each other, and click the assembly into place. In some embodiments, the magnets are color coded, to allow the installer to distinguish positive poles from negative poles. In some embodiments, the metal framing element also contains colorPATENT 6803*159914PCT codes, to facilitate orienting the magnets into matching configurations. In some embodiments, the opening in the framing element is asymmetric, and the endcap has a matching asymmetry, such that the tube can only be slide through the frame in a manner that would encourage the endcaps to align.

[0085] In alternative embodiments, the top of the tubes are bonded to a top cap that is too wide to pass through holes in the framing system, in order to prevent tubes from falling through. In some embodiments, the top cap contains hooks or protrusions to secure the system to the framing element. In some embodiments, the framing element has matching recessed areas to ensure the protrusions lock in place.

[0086] Products of manufacture and Structures

[0087] Provided are products of manufacture and structures comprising TES systems as provided herein. In alternative embodiments provided are HVAC systems comprising TES systems as provided herein. In alternative embodiments, the structure comprises a building, a shed, a ship, a train, a tunnel, an automobile, an airplane or a boat.

[0088] Any of the above aspects and embodiments can be combined with any other aspect or embodiment as disclosed here in the Summary, Figures and / or Detailed Description sections.

[0089] As used in this specification and the claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise.

[0090] Unless specifically stated or obvious from context, as used herein, the term “or” is understood to be inclusive and covers both “or” and “and”.

[0091] Unless specifically stated or obvious from context, as used herein, the term “about” is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. About (use of the term “about”) can be understood as within 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12% 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from the context, all numerical values provided herein are modified by the term “about.”

[0092] Unless specifically stated or obvious from context, as used herein, the terms “substantially all”, “substantially most of’, “substantially all of’ or “majority of’PATENT 6803*159914PCT encompass at least about 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 99.5%, or more of a referenced amount of a composition.

[0093] The entirety of each patent, patent application, publication and document referenced herein hereby is incorporated by reference. Citation of the above patents, patent applications, publications and documents is not an admission that any of the foregoing is pertinent prior art, nor does it constitute any admission as to the contents or date of these publications or documents. Incorporation by reference of these documents, standing alone, should not be construed as an assertion or admission that any portion of the contents of any document is considered to be essential material for satisfying any national or regional statutory disclosure requirement for patent applications. Notwithstanding, the right is reserved for relying upon any of such documents, where appropriate, for providing material deemed essential to the claimed subject matter by an examining authority or court.

[0094] Modifications may be made to the foregoing without departing from the basic aspects of the invention. Although the invention has been described in substantial detail with reference to one or more specific embodiments, those of ordinary skill in the art will recognize that changes may be made to the embodiments specifically disclosed in this application, and yet these modifications and improvements are within the scope and spirit of the invention. The invention illustratively described herein suitably may be practiced in the absence of any element(s) not specifically disclosed herein. Thus, for example, in each instance herein any of the terms "comprising", "consisting essentially of, and "consisting of' may be replaced with either of the other two terms. Thus, the terms and expressions which have been employed are used as terms of description and not of limitation, equivalents of the features shown and described, or portions thereof, are not excluded, and it is recognized that various modifications are possible within the scope of the invention. Embodiments of the invention are set forth in the following claims.

[0095] A number of embodiments of the invention have been described.

[0096] Nevertheless, it can be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.

Claims

PATENT 6803*159914PCT WHAT IS CLAIMED IS:

1. A hermetically sealed (or air-tight, or liquid impermeable) package or container comprising at least one phase change material (PCM), wherein the hermetically sealed package comprises a PCM disposed (or contained) in a plurality of metal tubes, wherein optionally each of the PCM-comprising plurality of metal tubes is sealed under a vacuum.

2. The hermetically sealed package or container of claim 1, wherein the plurality of PCM-comprising metal tubes comprise or are fabricated from aluminum or an Al alloy or stainless steel.

3. The hermetically sealed package or container of claim 2, wherein the volume of the tube is more than about 50% filled with the PCM, or the volume of the tube is filled with PCM to within about 50%, 60%, 70%, 80% or 90% or more (or between about 45% to 99%) of the pipe’s capacity before sealing.

4. The hermetically sealed package or container of claim 2 or claim 3, wherein the contents of the tube further comprise a thermally conductive material, and optionally the thermally conductive material comprises a metal mesh or metal flake.

5. The hermetically sealed package or container of any of claims 1 to 4, wherein the contents of the plurality of tubes further comprise a magnetic ball or a plurality of magnetic balls, and optionally the magnetic ball is a hollow stainless-steel ball, or the magnetic ball comprises a permanent magnet embedded in a low density polymer, and optionally the polymer comprises a cross-linked silicone.

6. The hermetically sealed package or container of claim 5, further comprising a magnetometer disposed outside the tube, wherein the magnetometer is used to detect the level of the magnetic ball within the tube.

7. The hermetically sealed package or container of any of claims 1 to 6, wherein the hermetically sealed package or container comprising the plurality of tubes is hermetically sealed using a process comprising tungsten inert gas welding (TIG), laser welding, ultrasonic welding, metal Inert Gas (MIG) welding, shielded metal arc welding (SMAW), flux-cored arc welding (FC AW), plasma arc welding (PAW) or any combination thereof.PATENT 6803*159914PCT8. The hermetically sealed package or container of any of claims 1 to 7, wherein the plurality of tubes is hermetically comprising PCM contained within are sealed using a process comprising tungsten inert gas welding (TIG), laser welding, ultrasonic welding, metal Inert Gas (MIG) welding, shielded metal arc welding, shielded metal arc welding (SMAW), flux-cored arc welding (FC AW), plasma arc welding (PAW) or any combination thereof.

9. A system for thermal management in a building HVAC system, comprising a plurality of hermetically sealed packages or containers comprising phase change material (PCM) hermetically sealed in a plurality of tubes or tubular structures, wherein the hermetically sealed packages or containers comprising the plurality of tubes or tubular structures are disposed or fabricated in a ductwork or plenum, and optionally the hermetically sealed packages and the plurality of tubes are disposed or fabricated, or secured, immediately below, or substantially close to and below, a rooftop unit (RTU) air conditioner or heater or HVAC.

10. A system for thermal management in a building HVAC system, comprising a plurality of hermetically sealed packages or containers as set forth in any of claims 1 to 8.

11. The system for thermal management of claim 9 to claim 10, comprising a frame disposed underneath or attached below a rooftop air conditioner or a rooftop unit (RTU) or HVAC, wherein the hermetically sealed packages or containers comprising tubes comprising phase change material are affixed to the frame.

12. The system of any of claims 9 to 11, wherein the frame is physically affixed to a curb underneath the rooftop unit (RTU).

13. The system of any of claims 9 to 12, wherein the hermetically sealed (or air-tight, or liquid impermeable) packages or containers are separated by an anchor affixed to each end of the hermetically sealed package away from the frame.

14. The system of any of claims 9 to 13, further comprising at least one turbulence-inducing element,PATENT 6803*159914PCT and optionally the at least one turbulence-inducing element is or is fabricated a turbulator, and optionally the at least one turbulence-inducing element is or is fabricated as a winglet.

15. An HVAC system comprising or has fabricated therein a system for thermal management of any of claims 9 to 14, or a plurality of hermetically sealed packages or containers as set forth in any of claims 1 to 8.

16. A building, a shed, a ship, a train, a tunnel, an automobile, an airplane or a boat comprising or having fabricated therein an HVAC system of claim 13, or a system for thermal management of any of claims 9 to 14, or a plurality of hermetically sealed packages or containers as set forth in any of claims 1 to 8.

17. Use of an HVAC system to thermally regulate a building, a shed, a ship, a train, a tunnel, an automobile, an airplane or a boat, wherein the HVAC systems comprises or has fabricated therein a system for thermal management of any of claims 9 to 14, or a plurality of hermetically sealed packages or containers as set forth in any of claims 1 to 8.

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