Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F3/00—Plate-like or laminated elements; Assemblies of plate-like or laminated elements
  • F28F3/02—Elements or assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with recesses, with corrugations
  • F28F3/022—Elements or assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with recesses, with corrugations the means being wires or pins
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
  • F28F13/003—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by using permeable mass, perforated or porous materials
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F21/00—Constructions of heat-exchange apparatus characterised by the selection of particular materials
  • F28F21/06—Constructions of heat-exchange apparatus characterised by the selection of particular materials of plastics material
  • F28F21/067—Details

Definitions

• the present invention relates to a heat exchanger, which is used in a heat recovery system wherein supplying fresh fluid to be heated up and exhausting fluid to be cooled down are simultaneously carried out to perform heat exchange between the supply fluid and the exhaust fluid.
• heat exchangers are commonly used e.g. for ventilation of buildings, wherein the fluid is a gaseous fluid, such as air.
• the heat recovery units presently used in single-family houses have dimensions of say height x width x depth of 0.85 x 0.60 x 0.55 m 3 . They contain an internal heat exchanger of about 0.50 x 0.50 x 0.30 m 3 , four 150 mm air pipes and two small ventilators.
• Such a compact heat exchanger is known for example from DE-A-100 08 681 .
• DE-A-100 08 681 discloses a heat exchanger that has a gas inlet and outlet to include heat-up and cooling chambers completed with corrugated spacers, which are - preferably - made of corrugated paper.
• the chambers are preferably stacked in rows with fleece material, which is placed round the chamber and fixed to the respective spacers.
• the chambers are fixed by stacked arrangement of spacers and joined by fleece materials as secured to any one spacer in each case.
• Inlets and outlets should be arranged at right angles to one another. According to DE-A-100 08 681 the heat exchanger disclosed should have high efficiency and at the same time a more compact size than the prior art units.
• the heat exchanger of DE-A-100 08 681 still leaves room for improvement.
• the prior art heat exchanger is limited to gaseous fluids.
• gaseous fluids such as air
• drawbacks when applying the heat exchanger of DE-A-100 08 681 , in particular when the air is loaded with high amounts of water vapour.
• the demand for a ventilation system with a heat exchanger in cold areas or indoor warm swimming pools has increased with the spread of such kind of heat exchanges.
• Such environments have a problem in that a great temperature difference between supplied air and exhaust air is apt to form vapour condensation and that the above mentioned corrugated paper - although preferably being resistant to humidity - cannot withstand long use because of deformation due to vapour condensation.
• the present invention has for its object to reduce the mentioned drawbacks of the prior art. Further objects will become evident by studying the embodiments in the description.
• a heat exchanger for fluids which heat exchanger comprise each an inlet and an outlet for a fluid to be heated up and for a fluid to be cooled down, at least one heat-up chamber and at least one cooling chamber, wherein the chambers are separated by a means to carry out heat transfer there between and wherein at least one of the chambers comprises a spacer, the invention being that the spacer comprises a three-dimensional mat from thermoplastic filaments, which mat has an open structure, and which filaments are bonded at least partly at their crossing points.
• bonding of the filaments that form the mat can be accomplished by various methods, including but are not limited to applications of glues, it is preferred that the filaments are bonded by thermal fusion, either by melting partially the filaments themselves or by the application of binders that have a melting point lower than the melting point of the filaments. These binders can also be part of the filaments, as for example may form the sheath of a core-sheath filament forming the mat of the invention. Those measures are known to the skilled person.
• At least one of the fluids to be heated up or to be cooled down by the heat exchanger of the invention is a gaseous fluid, even more preferably both fluids to be heated up and to be cooled down consist mainly or entirely of air.
• the main use of the heat exchanger is in ventilation systems of buildings, where both fluids to be treated consist of air.
• the invention is not limited to that and the heat exchangers according to the invention may also be used to treat cooling air or exhaust air in industrial processes.
• the entire spacer allows - due to its open structure - high amounts of fluids to pass through the respective chamber.
• the mat causes the fluid, such as a gaseous stream, to become not only turbulent, but micro-turbulent without causing substantial pressure losses during operation.
• the micro-turbulence on either side of the means to carry out heat transfer the overall efficiency increases substantially compared to the known heat exchangers, which in turn allows making them compacter.
• This additional reduction in size - as mentioned above - is a major advantage; this applies as well to small units for private housing as for large units for large buildings and industrial use.
• the spacer is made from thermoplastic filaments renders it entirely insensitive to humidity, increasing the lifetime of the heat exchanger, in particular in environments with high vapour condensation.
• An additional advantage lies in the fact that such mats as spacer render a better resilience to the entire structure, which also leads to an increase of the durability of the structure and is of help during the production of the heat exchanger, when the matting is to be handled, and during cleaning operations.
• the heat exchanger comprises a series of heat-up chambers and a series of cooling chambers that are piled up.
• the chambers are piled up in an alternating manner, i.e. a cooling chamber followed by a heat-up chamber followed by a cooling chamber and so on.
• any of the chambers comprises a three-dimensional mat from thermoplastic filaments as spacer.
• this consists of a thin plate or a foil which is made of a material that is gas impermeable, i.e. tight and insensitive to humidity. Furthermore, good heat conductivity will contribute to the efficiency of the heat exchanger. Any plate that is sufficiently thin of a suitable metal, such as aluminium, or a foil could for example achieve this.
• both the gaseous fluids to be cooled down or heated up consist of air.
• the means to carry out heat transfer between the chambers is a foil made of a material that is air impermeable and water vapour permeable. This leads to good exchange and transport of water vapour throughout the entire structure, rendering the heat exchanger less susceptible to condensates.
• foils that are air impermeable and water vapour permeable An example is foils made of a copolyetherester and sold under the trade name Sympatex® by Sympatex Technologies GmbH, Wuppertal (Germany).
• thermoplastic filaments of the three-dimensional mat comprise polyamide 6 as main component.
• This material can be spun laid into various homogeneous three-dimensional structures in a convenient and reproducible way.
• polyamide 6 is a very durable polymer, which is insensitive to low temperatures.
• the three-dimensional mat comprises an open random structure, i.e. forming flow paths for the fluid without a preferred flow direction, thus enhancing the formation of micro-turbulences and avoiding too high pressure loss during operation.
• vortices within the streaming fluid are being created.
• these vortices exhibit diameters that are less than one half (0.5), more preferably less than one tenth (0.1), of the hydraulic diameter (D) of the flow path within the three-dimensional mat.
• a particularly preferred three-dimensional mat exhibiting such a structure is commercially available under the trade name Enka®-Spacer from Colbond Geosynthetics GmbH, Obernburg (Germany).
• Three-dimensional mats from the Enka®-Spacer type have the advantage that they can be used in a convenient and reproducible manner due to the fact that their weight-area-ratio is very constant. This facilitates dosage of the material and as a consequence the reproducibility of the efficiency of the heat exchanger.
• the means to carry out heat transfer - also known as separation layer between the heat-up and the cooling chamber - is fixed to the top side and/or to the bottom side of the three-dimensional mat. This can preferably be accomplished by thermal fixing of this means to the three-dimensional mat, which renders the assembly of the structure very easy and durable.
• the heat exchanger is formed by simply piling up the means to carry out heat transfer that are (pre-) fixed to the top side or to the bottom side of the three-dimensional mat.
• the inlet(s) and outlet(s) are arranged such that the fluids to be heated up and the fluids to be cooled down have a maximum contact without being intermixed.
• the fluid to be heated up can only stream into and through the heat-up chamber(s) of the heat exchanger and the fluid to be cooled down only into and through the cooling chamber(s). This can be performed e.g. by sealing those sides of the chambers that should not be reached by a respective fluid.
• Those measures are known to the skilled person. Examples for such constructions for gaseous fluids can be found in DE 100 08 681 (Fig. 1 and Fig. 3), which are hereby incorporated by reference.

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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)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

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Publications (1)

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Family Applications (1)

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Citations (4)

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• 2006
  • 2006-06-24 EP EP06013075A patent/EP1870657A1/de not_active Withdrawn
• 2007
  • 2007-06-19 WO PCT/EP2007/005390 patent/WO2007147562A1/en not_active Ceased

Patent Citations (4)

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