Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H3/00—Air heaters
  • F24H3/002—Air heaters using electric energy supply
  • F24H3/004—Air heaters using electric energy supply with a closed circuit for a heat transfer liquid
• • 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
  • F28D1/00—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators
  • F28D1/02—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid
  • F28D1/0226—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid with an intermediate heat-transfer medium, e.g. thermosiphon radiators
• • 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
  • F28D1/00—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators
  • F28D1/02—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid
  • F28D1/04—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid with tubular conduits
  • F28D1/053—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid with tubular conduits the conduits being straight
  • F28D1/05308—Assemblies of conduits connected side by side or with individual headers, e.g. section type radiators
• • 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
  • F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
  • F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
  • F28D15/0275—Arrangements for coupling heat-pipes together or with other structures, e.g. with base blocks; Heat pipe cores

Definitions

• the invention relates to a radiator more particularly for home heating, and operating with a heat transfer fluid. More specifically, the heat transfer fluid used in the radiator of the invention operates in two-phase form, in particular liquid vapor.
• Heat-transfer-medium radiators are also known in which said fluid, generally oil, is heated by means of an electric heating element and passes through a heating body, at which heat transfer is effected to the heating element.
• said fluid generally oil
• said heating body is heated by means of an electric heating element and passes through a heating body, at which heat transfer is effected to the heating element.
• ambient air by natural convection. Due to the presence of a heating body whose exchange surface is relatively large, the temperature gradient is reduced with the ambient air so that the convective air movements in the room in question are limited.
• radiators in which the fluid operates in monophasic regime.
• said fluid remains in the liquid state.
• the heat transfer fluid heats up in contact with an electric heating element, lightening and rising inside the heating body.
• the coolant gives up to the ambient air part of the heat through the wall of the heating body, and corollary cools.
• the fluid thus cooled becomes denser, and therefore heavier, down by gravity in the lower part of the radiator.
• it is therefore necessary to have a minimum temperature difference between the fluid amount (hot) and the descending fluid (cold), directly dependent on the pressure losses of the fluid generated by its circulation.
• a heat-transfer fluid radiator operating in two-phase mode, in particular liquid / vapor mode.
• the operation of such a radiator is as follows: The heat transfer fluid in the liquid state rests by gravity in the lower part of the radiator traversed by a heating element, constituted by a fluid mounted in temperature, and sealingly passing through the base of said radiator.
• the coolant Under the effect of heat, the coolant is vaporized, said vapor then rising in the internal structure of the radiator, in particular at a heating body, at which a heat transfer occurs.
• the latter condenses.
• the condensate thus formed is in liquid form, and returns by simple gravity in the lower part of the radiator.
• the heating element when the heating element is directly in contact with the heat transfer fluid for heating thereof, as is the case for example in the document WO-A-02/50479, it may be damaged when the volume of liquid is too weak. Indeed, the vapor phase in which the heating element is predominantly, or even completely, bathed, is not sufficient to absorb the energy of the heating element which can therefore undergo overheating.
• the object of the present invention is to solve the problem of overheating of the heating element and maximum acceptable pressure by the radiator.
• the invention provides a radiator for home heating with heat transfer fluid operating in two-phase form, said heat transfer fluid consisting of a mixture of at least two different heat transfer liquids comprising: a reservoir of said heat transfer fluid;
• a hot source intended to raise the temperature of said heat transfer fluid to a temperature such that it causes a phase change of said fluid
• a heating body at which the transfer of heat with the air takes place ambient having a number n of channels, in communication in the lower zone with the reservoir, n being equal to 1.
• the heat transfer liquids having between them different boiling temperatures of at least ten degrees Celsius, and the lowest boiling temperature liquid represents from 70% to 95% of the volume of the mixture for a temperature of it approximately equal to 20 0 C.
• the at least two heat transfer liquids are miscible with each other.
• the vapor formation phase is performed in at least two consecutive stages as the temperature of the heating element increases.
• the presence of the heat transfer fluid of higher boiling temperature also meaning a more dense and less volatile liquid, ensures the presence of a minimum level of liquid in the collector of the radiator, thus avoiding the phenomenon of drying of the element. heating.
• the heat-transfer fluid can be a mixture of at least two types of fluorocarbon or hydrofluorocarbon aliphatic chains, especially hydrogenofluoroethers.
• the heat transfer fluid comprises two different heat transfer liquids, the first liquid being methoxy-nonafluorobutane, and the second liquid being decafluoro-3-methoxy-4-trifluoromethylpentane, and in that the heat transfer liquid with a lower boiling point constitutes approximately 95% of the volume of the mixture for a temperature of this equal to 20 ° C.
• the heat transfer fluid is a mixture of three different heat transfer liquids, the first liquid being methoxy-nonafluorobutane, the second liquid being decafluoro-3-methoxy-4-trifluoromethylpentane, and the third liquid being a product corresponding to the formula HF 2 C- (OC 2 F 4 ) m - (OCF 2 ) n -OCF 2 H, in which m and n are natural numbers with 0 ⁇ m ⁇ 3 and 0 ⁇ n ⁇ 3, and advantageously ZT-130 ® , and the first, second and third liquids respectively represent approximately 85%, 10% and 5% of the volume of the mixture for a temperature thereof equal to 20 ° C.
• the section S of the connection between the heat transfer fluid reservoir, situated in the lower part of said radiator and the heating body, capable of having a plurality n of channels, n being equal to 1,
• AxP ⁇ 5 is greater than or equal to 1 expression: expression in which: - P denotes the power of the electrical resistance;
• the number of constituent channels of the heating body is a constant which depends on the nature of the fluid and the temperature thereof (A is expressed in m 2 .W "4/5 ).
• connection zones with a passage between the reservoir and the channels constituting the heating body respecting the aforesaid relationship, eliminates or decreases at least drastically the number of drops of heat transfer fluid in liquid form driven by the steam generated at the hot source, and therefore optimizes the operation of the radiator.
• connection zone of the constituent channels of the heating body at the reservoir opens above the electrical resistance.
• the zones for connecting the channels of the heating body at the level of the tank have their lower part at a minimum distance ⁇ above the line of greater tangency of the electric heating resistance passing through. the reservoir, said distance respecting the relationship ⁇ > 0.5 ⁇ D, wherein D is the diameter of said heating resistor.
• the filling coefficient ⁇ must be greater than the value of 0.0142, said coefficient ⁇ being defined by the ratio of the mass of vapor produced at 20 ° C. to the total mass of fluid introduced into the body of the radiator.
• FIG. 1 is a schematic, partially exploded representation of a known heat transfer fluid radiator.
• Figure 2 illustrates a cross-sectional view of such a radiator, but according to the invention.
• Figure 3 is a detailed schematic representation of the cross section of the lower zone of said radiator.
• Figure 4 is an illustration of a variant of the invention.
• Figures 5 and 6 are schematic sectional views illustrating one of the features of the invention.
• FIG. 1 shows a radiator with heat transfer fluid known per se.
• This radiator is in this case constituted by a plurality of unitary elements 1, constituting the heating body, all the elements being connected to a lower tank 3.
• These different elements 1 may, for example, be made of cast aluminum and, in order to optimize the transfer with the ambient air, may have fins 2 thus promoting the diffusion of heat within the room in which such a radiator is implanted. Within each of these elements 1 circulates a heat transfer fluid, the nature of which is adapted to the thermal function envisaged.
• This fluid may be water, ethanol, or a polymeric synthetic material, such as, for example, Rl 13 (chlorofluorocarbon), or a fluorocabonated or hydrofluorocarbonated aliphatic chain, and preferably a hydrogenofluoroether (such as HFE 7100 ® , HFE 7300 ® or HFE 7500 ® , marketed by 3M, or ZT-150 ® , ZT-130 ® or ZT-85 ® marketed by Solvay-Solexis).
• a polymeric synthetic material such as, for example, Rl 13 (chlorofluorocarbon), or a fluorocabonated or hydrofluorocarbonated aliphatic chain, and preferably a hydrogenofluoroether (such as HFE 7100 ® , HFE 7300 ® or HFE 7500 ® , marketed by 3M, or ZT-150 ® , ZT-130 ® or ZT-85 ® marketed by Solvay
• hydrogenofluoroether mainly a family of molecules corresponding to the following structure I:
• A, B, C and D represent linear or branched aliphatic groups having from 1 to 10 carbon atoms, the hydrogens of which are wholly or partially substituted by fluorine atoms, and wherein m and n are natural numbers with 0 ⁇ m ⁇ 3 and 0 ⁇ n ⁇ 3.
• the aforementioned aliphatic groups are alkyl groups.
• the HFE 7100 ® is a mixture of 1-methoxy-nonafluorobutane, and 1-methoxy- nonafluorotertiobutane
• HFE 7300 ® is the decafluoro-3-methoxy-4-trifluoromethyl methylepentane.
• the assembly of the various elements 1 between them constitutes the heating body itself, and are each provided with a vertical channel 4, opening in the lower zone at the level of the tank 3 by a connection zone 5.
• an electric heating resistor 6 is inserted into the lower reservoir 3 and passes through it over substantially its entire length.
• a resistor may for example consist of a double insulated heating cartridge.
• the connection zone 5 between the channel (s) 4 of the heating body and the tank 3 located in the lower part of said radiator has a section S corresponding to the following formula:
• P represents the power of the electrical resistance 6
• n is the number of channels 4 and therefore the number of elements 1 constituting the heating body opening into the same reservoir 3
• A is a constant, which depends on the nature of the fluid measured at a given temperature.
• the constant A results from the practice of a liquid droplet flow model driven by a vapor flow, such as the Wallis and Kutateladze model.
• the model in the context of the present invention is modified to take into account the thermal power injected, found directly in the source term of the production of the steam flow in the channels constituting the radiator. Under these conditions, the constant A has the following formula:
• K is a function of the physical properties of the fluid and is expressed as follows:
• h is the latent heat of vaporization of the fluid and p is the density (liquid or vapor).
• the constant A is valid when the coolant consists of only one of the following elements:
• the coolant is water, developing 1,000 watts electric, and having ten elements 1, so ten channels 4 in parallel, the connection section 5 between each of the channels and the reservoir 3 must be greater than 0.27 cm 2 .
• the section of the connection zone 5 must then be greater than or equal to 0.383 cm 2 .
• FIG. 3 illustrates the operating mode of such a radiator.
• the upward arrows illustrate the vaporization and then the ascent of the coolant in the vapor phase at the level of the heating body, and the downward arrows illustrate said fluid then condensed in contact with the side walls of the channel 4 considered, falling down in liquid form and by simple gravity in the tank 3 via the connection zone 5.
• the electrical resistance 6 is further dimensioned such that the thermal flux density at the surface of the latter does not exceed 3 watts per cm 2 , in order to vaporize the heat transfer liquid in the form of small bubbles and consequently in order to reduce the phenomenon of noise generated conventionally in heat transfer radiators.
• the surface of the heating rod or electrical resistance 6 in contact with the heat transfer fluid must be greater than 330 cm 2 , regardless of the number of channels and regardless of the heat transfer fluid.
• connection zone 5 of the channels 4 at the reservoir 3 opens above the upper maximum tangency line 7 of said heating rod 6 by a distance ⁇ greater than or equal to 0.5 ⁇ D, D being the diameter of the heating rod or electrical resistance 6.
• connection area must not be flooded.
• the coefficient ⁇ of filling of the radiator is greater than 0.0142, the coefficient ⁇ being defined by the following relation:
• the mass of vapor at 20 ° C. is determined by the following expression:
• ⁇ i denotes the specific mass volume of the saturation liquid at 20 ° C. (in rnVkg).
• This criterion is respected if a maximum of 400 ml of HFE 7100 ® , 5 ml of water or 39 ml of ethanol is introduced into a radiator with an internal volume of 4 liters.
• the radiator of the invention thus makes it possible to overcome the various disadvantages mentioned in relation with the radiators of the prior art in a simple and effective manner and also makes it possible to regulate the operation of such a radiator in a facilitated manner.
• the heat-transfer fluid consists of at least two heat-transfer liquids, preferably miscible, having boiling temperatures different from at least 10 ° C., and preferably from 20 ° C., and more particularly mixture of at least two types of aliphatic chains fluorocarbon or hydrofluorocarbonées, including two types of hydrogénofluoroéthers from the HFE ® 7100, HFE 7300 ®, HFE ® 7500, the ZT 150 ®, the ZT 130 ® and the ZT-85 ® .
• a mixture comprising from 70% to 95% by volume of the heat transfer fluid, when the temperature of said fluid is 20 ° C., having the lowest boiling temperature, this low boiling temperature preferably being close to 60 0 C, in particular: - a mixture of 67% of HFE 7100 ® and 33% HFE ® 7300 (hereinafter
• Product ® ZT 130 is deemed to correspond to the formula II below: HF 2 C- (OC 2 F 4) m - (OCF 2) n OCF 2 H in which m and n are integers with 0 ⁇ m ⁇ 3 and 0 ⁇ n ⁇ 3.
• Such a mixture has the effect, in particular, compared to a coolant consisting of a single heat transfer liquid: • to lower the vapor pressure in the radiator;
• a temperature difference between the hottest point and the coldest point of the heating body 6 less than 0.6 0 C, when the heating element 6 operates at its nominal power Qn (maximum operating power allowed when the radiator is in use);
• a temperature difference between the hottest point and the coldest point of the heating body 6 less than 0.3 0 C, when the heating element operates at 1.24 times its nominal power Qn (Qn ' 1, 24 * It is usually the power at which vapor pressure tests are carried out to know if the radiator is capable of supporting it); a drop in the vapor pressure of 40 mbar with respect to a reference heat transfer fluid commonly used in radiators of the state of the art, in particular HFE 7100 ® , when the heating element 6 is operating at its nominal power Qn and "a decrease of the vapor pressure of 60 mbar compared to the heat transfer fluid of reference, when the heating element 6 operates at 1.24 times its nominal power Qn.
• the above mixtures allow a reduction in the operating pressure with respect to the reference fluid, while ensuring a good homogeneity of the radiator temperature since the maximum temperature difference observed is less than 50.degree .
• the mixture 2 provides a better homogeneity of the temperature while the mixture 4 allows a more significant decrease in the operating pressure of the radiator.
• the mechanical design pressure of the radiator is twice the vapor pressure obtained at 1.24 times the nominal power Qn, it can be deduced that the mechanical stress is reduced by nearly 800 mbar when the mixture 4 is used against 120 mbar when the mixture 2 is used.
• the radiator and more particularly the section S of these channels, the distance ⁇ and the coefficient ⁇ of filling are chosen according to the mixture in question, in a manner similar to that described above.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Central Heating Systems (AREA)
• Cooling Or The Like Of Electrical Apparatus (AREA)
• Air-Conditioning For Vehicles (AREA)

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• 2009
  • 2009-01-19 FR FR0950302A patent/FR2941290B1/fr not_active Expired - Fee Related
  • 2009-12-28 EP EP09805791.2A patent/EP2379951B1/de active Active
  • 2009-12-28 WO PCT/FR2009/052703 patent/WO2010081957A1/fr active Application Filing
  • 2009-12-28 JP JP2011545776A patent/JP2012515320A/ja not_active Withdrawn
• 2011
  • 2011-06-30 US US13/174,117 patent/US8909034B2/en not_active Expired - Fee Related

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