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EP-4739736-A1 - ADDITIVE FOR A HEAT TRANSFER FLUID, AND A HEATING AND/OR COOLING SYSTEM INCORPORATING THE SAME

EP4739736A1EP 4739736 A1EP4739736 A1EP 4739736A1EP-4739736-A1

Abstract

The present invention provides a composition provided for use as an additive to a heat transfer fluid. The composition comprises a silicone surfactant or polyether, or comprises a silsesquioxane compound. The invention also provides a heat transfer fluid for use in a heating and/or cooling system, wherein the heat transfer fluid includes water or a refrigerant and at least one additive in the form of the aforementioned composition. The invention also provides heating and cooling systems incorporating the heat transfer fluid.

Inventors

  • WILSON, ROBERT
  • YASEEN, Dr Mohammed
  • ELTAYEB, Ahmed

Assignees

  • Safesold Ltd

Dates

Publication Date
20260513
Application Date
20240828

Claims (20)

  1. CLAIMS 1. A composition provided for use as an additive to a heat transfer fluid, characterized in that said composition comprises a silicone surfactant or polyether, or comprises a silsesquioxane compound.
  2. 2. A composition according to claim 1, wherein said silicone surfactant or polyether comprises a linear- or branched-chain siloxane.
  3. 3. A composition according to claim 1, wherein said silicone surfactant comprises a branched-chain siloxane and has the general formula: wherein a = R = any one of the following functional groups: an alkyl group; a mono- or poly-unsaturated alkyl group; a fluorocarbon or hydrofluorocarbon; an aryl group; a heterocyclic group; ; - (CH2)2-COOH, a fluorocarbon or hydrofluorocarbon, or , R 2 = -COOH, -NH 2 , an alkyl group, or a fluorocarbon or hydrofluorocarbon.
  4. 4. A composition according to claim 3, wherein said branched- chain siloxane has the formula: wherein a = 0- and x = 1-5.
  5. 5. A composition according to claim 4, wherein a = 0-20, b = 1- 10, m = 8, n = 0, and x = 3.
  6. 6. A composition according to claim 4, wherein a = 0, b = 1, m = 8, n = 0, and x = 3.
  7. 7. A composition according to claim 4, wherein a = 8, b = 4, m = 8, n = 0, and x = 3.
  8. 8. A composition according to claim 4, wherein a = 20, b = 10, m = 8, n = 0, and x = 3.
  9. 9. A composition according to claim 1, wherein the sil icone surfactant or silsesquioxane compound is added to the heat transfer fluid in an amount such that it is present at a concentration of between 50-1,000ppm, in use.
  10. 10. A composition according to claim 1, wherein the composition is provided in combination with one or more further compositions, provided in the form of carbon-based nanoparticles and/or metal oxide nanoparticles.
  11. 11. A composition according to claim 10, wherein said carbon- based nanoparticles are provided as graphene oxide nanoparticles at a concentration of about 0.01 v/v% to 1 v/v%.
  12. 12. A composition according to claim 1, wherein the composition is provided in combination with one or more further compositions, provided in the form of any or any combination of scale or corrosion inhibitors, biocides and/or anti-freeze agents.
  13. 13. A composition according to claim 12, wherein said scale or corrosion inhibitors are selected from any or any combination of sodium nitrite, sodium molybdate, a combination of sodium nitrite and sodium molybdate, or a polyamine.
  14. 14. A composition according to claim 12, wherein said biocides are selected from any or any combination of isothiazolone, bronopol, or tetrakis(Hydroxymethyl)-Phosphonium Sulfate (THPS).
  15. 15. A composition according to claim 12, wherein said anti- freeze agent are selected from monoethylene glycol or monopropylene glycol.
  16. 16. A composition according to claim 12, wherein the composition is provided in combination with at least a scale or corrosion inhibitor and a biocide.
  17. 17. A heat transfer fluid for use in a heating and/or cooling system, said heat transfer fluid including: water or a refrigerant; and at least one additive, characterized in that said additive comprises a silicone surfactant or polyether, or comprises a silsesquioxane compound.
  18. 18. A heat transfer fluid according to claim 17, wherein said silicone surfactant or polyether comprises a linear- or branched-chain siloxane.
  19. 19. A heat transfer fluid according to claim 18, wherein said branched-chain siloxane has the formula: wherein a = 0- and x = 1-5.
  20. 20. A heat transfer fluid according to claim 19, wherein a = 0- 20, b = 1-10, m = 8, n = 0, and x = 3.

Description

Additive for a heat transfer fluid, and a heating and/or cooling system incorporating the same The invention to which this application relates is an additive for a heat transfer fluid, and a heating and/or cooling system incorporating the same therein. Almost 40% of all the energy used in the U.K. is used to heat our homes and places of work. Nearly all this energy (85%) is used to heat water. This water is heated in boilers, by heat pumps or other means to temperatures up to 80oC and circulated through radiators or fan coils to heat individual spaces. The efficiency of boilers, heat pumps etc and radiator/fan coil design has been optimised to the extent that further improvements would not greatly improve fuel savings. Surfactants and their effect on energy improvement in a water environment have been known for some time. Most commonly, Alkyl Polyglucosides (APG’s) have been used to improve saltwater evaporation, and it has been demonstrated that less energy was used to evaporate water in a vat when the surfactant was added. It has been shown that APG’s are a thermally stable category of surfactant, which can improve energy efficiency under boiling conditions. However, it remained unknown for some time why radiators should become hotter in a central heating system with the added APG surfactant, as only a very small proportion of the circulating water in a heating circuit contacts hot metal in the boiler. The inventors of the present invention eventually surmised that the improvement in radiator temperature was associated with the reduced surface tension of the water in the system, caused by the presence of the surfactant. It was suggested by the inventors that the lower surface tension allowed water to access more of the radiator’s interior surface, thereby improving heat transfer through the radiator and into the room in which it is located. Treatments based on APG (mainly coco-glucoside) have been commercialised and these have delivered around 10%-15% energy savings. The main reason proposed for why they work is that they lower surface tension and allow the water to access more of the radiator or fan coil surface. Such examples are disclosed in granted British patent GB 2494073 and in published international patent application publication number WO 2016/128724 – both being disclosures developed by the inventor of the present application. Metal surfaces are not smooth and contain micro-indentations or micro-cracks, as well as much smaller indentations including nano-cracks. Water, which has high surface tension, ca 72 mN/m at 70o C to 80o C, will sit on top of most of these micro- indentations and thus have a lower surface contact. Agents that reduce the surface tension of water can result in better wetting and improved surface contact at the metal – liquid interface. The addition of 1,000 ppm of certain surfactants to water reduces its surface tension down to ca. 30 mN/m, improving the wettability of water and enhancing “liquid – metal” contact and therefore improving the transfer of heat. This mechanism has only recently been acknowledged in a peer reviewed journal (“Effect of surface tension on the thermal performance of a pulsating heat pipe – a review” Vaishnavi K. e t al. International Journal of Research in Engineering IT and Social Sciences ISSN 2250-0588; Volume 10, Issue 06; June2020 pps 29-34) stating that fluid physical properties play a large part in energy transfer and emphasising surface tension as being an important factor. The addition of a surfactant breaks the network of water structural bonding giving increased wettability and allowing more transport of water and the energy it contains on to the metal surface of for example a radiator or fan coil. Wettability hence depends on the interfacial tension between water and the metal surface. This is the adhesive force between the water and the metal, and the higher this force is, the wetter the surface will be. Surfactants have already been used in the UK, North America and in many other countries as energy saving products, and this capability has been heavily linked to the ability of these surface- active agents to lower the surface tension of water. However, while surfactants like alkyl polyglucosides (APG’s) reduce surface tension of water, they still do not allow water to access the complete surface. It is therefore an aim of the present invention to provide an improved additive for a heat transfer fluid of a heating and/or cooling system which overcomes the aforementioned problems associated with the prior art. It is a further aim of the present invention to provide an improved heat transfer fluid to maximise the thermal energy transfer from a heating/cooling system into a space in which it is located. It is yet a further aim of the present invention to provide improved heating and cooling systems which overcome the aforementioned problems associated with the prior art. According to a first aspect of the invention there is provided a