Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
  • F28D20/02—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat
  • F28D20/023—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat the latent heat storage material being enclosed in granular particles or dispersed in a porous, fibrous or cellular structure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
  • F28D20/02—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
  • F28D20/02—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat
  • F28D20/021—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using latent heat the latent heat storage material and the heat-exchanging means being enclosed in one container
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/14—Thermal energy storage

Definitions

• the invention relates to the efficient storage, with rapid absorption and extraction, of thermal energy.
• the invention provides a latent heat storage device in accordance with claim 1 of the appended claims.
• the latent heat storage device contains at least one phase change material (PCM) contained within containment means and comprises a containment vessel forming a supporting structural exoskeleton to provide support for the containment means.
• the containment means comprises very thin elastomeric material and is of a wall thickness that is much thinner than has previously been contemplated in the art. The thinness of the walls enables very efficient heat transfer to and from the PCM.
• the thin elastomeric material can be formed into any shape of thin section and providing a very large surface area to volume ratio, for example having many sided or circular chambers, and provided the distance through any section of PCM is small enough to effect rapid melting and freezing of the PCM.
• the containment means comprises thin elastomeric material formed as a continuous tube, filled with PCM and sealed at both ends, then folded along its length to occupy the maximum amount of space that is available within the containment vessel.
• This arrangement allows the amount of sealing required to be minimised and provides a very efficient means of maximising the amount of space used within the vessel by the containment means.
• An alternative advantageous form comprises an array of tubes joined by small web sections. This type of array can be formed by moulding or extrusion or can even be made using 3D printing technology techniques.
• the tubes can be sealed at each end and enables a maximum amount of space to be occupied within the vessel by the tubes.
• the elastomeric material is selected to have as thin a wall thickness as possible to structurally retain the PCM and at the same time to provide the minimum effect on the transfer of heat to and from the PCM. This enables the device of the invention to have a very rapid response time and to absorb and provide energy very quickly. Additionally it is effective even for very small temperature differences.
• the device may have a multiplicity of different PCM, with different properties, within the one vessel.
• the device may also have a multiplicity of different compartments within the one vessel, either with PCMs that are the same or that are different.
• the compartments may be formed using insulated or non-insulated panels.
• the flow of heat exchange fluid is controlled through the vessel and it may be directed to the different compartments in turn. The flow of fluid can be directed to different parts of the device to accommodate different requirements at different times.
• the device may have a multiplicity of vessels within the one device.
• the latent heat storage device vessel has a sealed lid. If the device is sealed, then gas or fluid can be injected into the sealed vessel to effect a different atmosphere or environment such as a reduced oxygen atmosphere for the benefit of any heat transfer fluid or other material's needs for a reduction in oxidation.
• gas or fluid can be injected into the sealed vessel to effect a different atmosphere or environment such as a reduced oxygen atmosphere for the benefit of any heat transfer fluid or other material's needs for a reduction in oxidation.
• the inert gas may be nitrogen or carbon dioxide.
• the device has a means whereby heat exchange fluid is supplied to the vessel and removed from the vessel, so as to be a closed circuit such that whatever fluid is supplied is also removed at the same time to avoid overfilling or emptying of the vessel.
• the elastomeric contained PCM is allowed to expand and contract according to its nature.
• the expansion and contraction can take place initially out of and back into the the vessel, preferably the top of the vessel.
• the containment means may subsequently expand into the heat exchange channels within which the heat exchange fluid flows.
• This arrangement has the particular advantage in that it can be used to provide an automatic limiting of the flow of fluid as the expansion acts to progressively restrict the flow of heat exchange fluid between the elastomeric tubes. This provides a particularly useful safety mechanism to prevent overheating of the PCM, elastomeric and/or other materials used.
• the vessel is arranged to provide the exoskeleton structural integrity for the elastomeric PCM, once the PCM has melted. If the device has internal compartments or dividers, these can also be used to provide the structural integrity for the elastomeric PCM, once the PCM has melted. This enables a far thinner wall thickness of the containment means to be used than has previously been achievable.
• the vessel may be surrounded by insulation.
• This may be any suitable insulating material including vacuum insulation.
• the device may be surrounded by a secondary insulated tank filled with water or any other suitable fluid, such that any thermal energy that escapes from the inner vessel or vessels will be absorbed and there will be minimal loss to the surrounding atmosphere.
• the thermal conductivity of certain PCMs may be improved by adding very small quantities of very fine powders of suitable conductive material to the PCM. If the particle sizes are small enough then they will remain suspended within the main body of the PCM. They will also have a tendency to get continually redistributed by any convection currents induced by the melting of the PCM.
• the invention further provides a latent heat storage device comprising a containment vessel, at least one phase change materal (PCM) and at least one PCM containment means wherein at least one very fine nano-particle conductive powder is added to the PCM to improve the transfer of thermal energy.
• PCM phase change materal
• the addition of very fine nano-particle conductive powders can significantly improve the performance of poorly conducting PCMs. Suitable examples include, but are not limited to, carbon and aluminium.
• the concentrations can vary depending upon the materials used but typically can be anything from 0.5% to 2%; larger concentrations may well reduce the amount of PCM volume and influence the overall performance. It is now possible to make up new composite materials utilising the properties of the different components to maximise the thermal capacity and heat transfer rates. Although it is possible to improve the situation the current technical specifications are exacting as there is a tendency for these materials to settle or separate out with time and the present invention enables these problems to be overcome.
• the vessel may be surrounded by secondary layers of different PCM filled elastomeric material.
• the PCM of the secondary layer may have a lower phase change temperature than the PCM of the vessel.
• the latent heat storage device of the invention is used with a solar heating device or other device, it can be arranged so that the heat exchange fluid feed- back temperature is lower than it would otherwise be; so as to maximise the efficiency of the solar heating or other device.
• Figure 1 shows a schematic cross-section of a latent heat storage device according to the invention.
• Figure 2 shows a more detailed view of a corner of the device shown in Figure 1.
• Figure 3 shows an example of a containment means in the form of a continuous round tube folded into six rods.
• Figure 4 shows an embodiment of the invention in form of a "tank within a tank”.
• FIG. 5 shows an embodiment of the invention, wherein separators can be used to direct the flow of heat exchange fluid through different compartments of PCM.
• Figure 6 shows an alternative shaped containment means, with detail shown in Figure 6a.
• Figure 7 shows a further alternative shaped containment means, with detail shown in Figure 7a.
• Figure 8 shows a possible packing arrangement of containment means of the type shown in Figure 3.
• a rapid absorption and extraction latent heat storage device comprises a means 1 for storing a phase change material 2 arranged within a containment vessel 3 (for which insulation is not shown in this example).
• the containment means 1 is in the form of rods or tubes, which are made out of elastomeric material 4 containing the PCM 2.
• a heat exchange fluid 6 flows along the length of the rods 1.
• the PCM 2 may advantageously have a fine nano-particle conductive powder such as carbon or aluminium added to improve its conductivity.
• the containment vessel 3, is shown as hexagonal but could be any shape that maximises the storage capacity for round rod-like multiple components 1 but the rods can be any shape provided they offer a thin enough section, for conduction, to enable heat transfer through the whole section in an acceptable time frame.
• the outer skin of the rods is made from an elastic material 4 which utilises the close proximity of all the adjacent rods to support them when the PCM 2 is in the liquid phase.
• the rods 1 have a small diameter and are long.
• the tubes have an external diameter of 10.5mm and an internal diameter of 10.0mm, and as such have a wall thickness of only 0.25mm.
• WO 95/16175 describes tubes of HDPE having an outer diameter of 38mm and an internal diameter of 32mm and thus having a wall thickness of 3.0mm. This thick a wall will limit the heat transfer that is possible between the heat exchange fluid and the PCM within the tube. Entry/exit pipes 13a allow the heat exchange fluid to be fed into and removed from the vessel 3.
• Figure 2 shows the detail of a comer of a containment vessel 3.
• the heat exchange fluid 6 passes through the spaces in between the rods 1.
• the tubular elastomeric material 4 used for the containment of the PCM 2 must be thin enough to not take up too much volume and also to conduct thermal energy efficiently. Initial prototypes have shown that many kilo watts of thermal energy could be stored and released in only a few minutes.
• Figure 3 shows a preferred example of a containment means of the invention.
• the containment means comprises a continuous tube 7, of preferably circular cross-section, folded into six rods 1. Where the folds take place at the top and bottom of the rods, while the PCM 2 is molten, this area can be shaped to provide the round rod like shape.
• the containment means 1 was made from one length of tubing nominally 4500 mm long. In this example there are only two seals 8 needed for each batch of six rods.
• the containment means 1 can be any desired length but handling and the strength of the tubing will create a practical limit.
• Figure 4 shows an embodiment of the invention in form of a "tank within a tank", where two different types of PCM 2a, 2b are housed within the same tank and separated by separators 9, which in this example are an internal block and an external block where the separators 9 are suitable internal insulation; typically capable of withstanding higher temperatures. Similarly external insulation 10 is also shown. Insulation can be made from any suitable materials including Vacuum Super Insulation.
• FIG 5 shows a different arrangement, where separators 11 are arranged within the containment vessel 3.
• the separators 11 can be used to direct the flow of heat exchange fluid 6 through the different compartments of the vessel 3 which can utilise different types of PCM 2 having different melting temperatures should this be required.
• the separators could be made out of any suitable insulation materials.
• the tubes 2 in this arrangement can advantageously be formed as an extruded array of tubes connected by thin webs between each adjacent tube.
• Each section in the containment vessel 3 has an array 50 fitted within the section. The arrays
• a single compartment vessel as shown in Figure 1 may have a single array 50 or a combination of two or more arrays to fill the vessel.
• each section of the vessel shown in Figure 5 may have one or more arrays to fill the sections of the vessel.
• Figure 6 shows a rod having a rectangular cross-section.
• the section depicted is effectively where the round rods depicted in Figure 1 are joined together.
• Figure 7 gives another example of different shaped rods.
• the vessel 3 is round and the elastomeric rods 14 are similarly shaped and are arranged as concentrical rings linked by small web sections 12 with heat-exchange fluid 6 flowing between the layers.
• heat-exchange fluid 6 flowing between the layers.
• this is in the form of a "corrugated" type outer surface 15, which can be seen in more detail in Figure 7a.
• the flow path could alternatively be accommodated by varying the shape of the vessel but the essential feature is that the rods are still supported and contained by the vessel as it acts as an exoskeleton for the main structure.
• Figure 8 shows a packing arrangement of a plurality of tubes 7 of the type shown in Figure 3, each folded into six rods 1 and close packed within a hexagonal containment vessel 3.
• a single entry/exit pipe 13b allows the heat exchange fluid 6 to flow in and out of the vessel 3, as required.
• the elastomeric material 4, containing the PCMs 2 is provided in the form of an extruded tube but the elastic film surrounding the PCMs can be sprayed on to the PCM material or the PCM material can be dipped into a solution. It is also possible to construct the elastomeric material using the 3D printing technologies so that the complete structure can be made as one unit, or as an assembly of smaller units.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• Filling Or Discharging Of Gas Storage Vessels (AREA)
• Extraction Or Liquid Replacement (AREA)
• Distillation Of Fermentation Liquor, Processing Of Alcohols, Vinegar And Beer (AREA)

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• 2007
  • 2007-12-19 GB GB0724776A patent/GB2455748A/en not_active Withdrawn
• 2008
  • 2008-12-19 US US12/809,105 patent/US20110030915A1/en not_active Abandoned
  • 2008-12-19 WO PCT/GB2008/004199 patent/WO2009077765A1/en active Application Filing
  • 2008-12-19 EP EP08861002A patent/EP2235466A1/de not_active Withdrawn
  • 2008-12-19 GB GB1012030.1A patent/GB2468619B/en active Active
  • 2008-12-19 CN CN2008801258723A patent/CN101932898B/zh not_active Expired - Fee Related

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