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
  • F28F1/00—Tubular elements; Assemblies of tubular elements
  • F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
  • F28F1/12—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element
  • F28F1/24—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element and extending transversely
  • F28F1/32—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element and extending transversely the means having portions engaging further tubular elements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F17/00—Removing ice or water from heat-exchange apparatus

Definitions

• the present invention relates to heat exchangers, its manufacture and use. It relates more particularly to those which are reversible and arranged outside especially those used in heat pumps or air conditioning.
• Heat exchangers can frost in critical ice setting conditions, ie when the temperature is between -5 ° C and 2 ° C and humidity reaches 85%, this results in a loss of performance, and may cause the complete shutdown of the exchanger.
• frost it is known to stop after a certain time the thermodynamic heating cycle to reverse evaporation and condensation. This has the effect of cooling the water on the warm side (the radiators), thus allowing the outdoor heat exchanger to heat up and melt the frost.
• this has a direct impact on the heating and decreases the performance of the machine.
• the transverse pitch the space between the copper tubes in the direction transverse to the direction of the air
• the fin pitch the space between two fins
• the object of the invention is to provide a high-performance anti-icing heat exchanger which allows a longer use in critical conditions while maintaining power and equivalent dimensions, while keeping the same amount of tubes and therefore in no time. not increasing the cost.
• the heat exchanger according to the invention comprises fins punched with holes surrounded by flanges, n tubes passing through n holes and n flanges, each hole and its flange having a diameter di and a height h, characterized in that the number of holes is greater than n and the n flanges have a height hi of between 1.8 and 4.2 mm.
• the free collars are additional obstacles to the air, to cause disturbances and forcing the heat exchange between the fin and the air.
• the latter may have different shapes and dimensions of the n flanges crossed by the tubes.
• the height hi n flanges will define the space between the fins.
• the combination of the additional free collars with the greater distance between the fins makes it possible to compensate the loss of exchange (by-pass) which could result from this greater distance for an equivalent power while considerably limiting the frost in a critical situation.
• the holes and the collars all have the same diameter. The manufacture and punching of the fins is thus easier.
• the number of holes is equal to 2n.
• the exchanges are thus doubled.
• the holes are aligned longitudinally and the tubes pass through one hole in two by alignment.
• the distribution of tubes and free collars are distributed evenly.
• the holes with their flanges may be spaced from each other at a constant pitch both transversely and / or longitudinally.
• the flanges are of cylindrical shape. This shape has the best surface of heat exchange with the air without generating a pressure drop on the air
• the fins are made of aluminum.
• the use of aluminum for the fins is a good compromise between thermal conductivity, ease of realization and cost.
• the use of copper fins although better driver is possible, but it is harder to work and more expensive.
• the tubes are made of copper. Copper is a good thermal conductor. The use of aluminum is also possible.
• the holes of a row are offset from those of adjacent rows. This allows a better distribution of air around the tubes and collars.
• This method has the advantage of being substantially close to the conventional method, except that more holes and flanges have to be stamped.
• These holes and its flanges can be of different shape: circular and cylindrical of identical diameter for those who receive the tubes and of diameter and / or of different or identical shape for those intended to remain empty.
• the method of heating a room according to the invention implements the heat exchanger with at least one of the preceding characteristics, it comprises two modes of operation:
• a first heating mode when the temperature is higher than 2 ° C
• a second heating mode when the outside temperature is between -5 ° C and 2 ° C and humidity reaches 85%
• a defrost and a heating alternate with a time interval Dt the passage from one to the other being automatically regulated
• tw is the humid temperature of the outside air in contact with the exchanger.
• the pitch of the fins of the exchanger according to the invention makes it possible to significantly increase the time between two defrosting operations with respect to an equivalent heat exchanger.
• the so-called "equivalent” heat exchanger a heat exchanger having the same number of tubes and which, for a given wet outside temperature, has the same the evaporation temperature. High humidity above 85% is the most unfavorable for the exchanger.
• the heat exchanger is thus such that the operating time in evaporator mode, or heating, without defrost is doubled compared to a conventional heat exchanger of the same power. Thanks to its additional collars arranged on the passage of the air one can obtain an equivalent power with a greater distance between the fins while limiting the frost in critical conditions, avoiding any loss of exchange.
• FIGS. 1 and 2 are views of the assembly of the exchanger according to the invention.
• FIG. 3 is a side view of the exchanger of the preceding figures
• FIG. 4 illustrates the heating capacity of a exchanger of the state of the art
• FIG. 5 illustrates the heating capacity of an exchanger according to the invention
• FIG. 6 is a heat exchanger of the state of the art
• FIG. 7 is a graph showing the interval between two defrostings with respect to the humid temperature of the air in contact with the exchanger.
• the top corresponds to the top of the figures and the bottom to the bottom
• the longitudinal part is parallel to the z axis of FIG. 6
• the transverse part is parallel to the x axis of FIG. .
• a heat exchanger 1 of the state of the art as illustrated in FIG. 6 comprises tubes 2 and fins 3.
• the tubes 2 are usually copper and bent pin 22. They are separated by a transverse pitch Pt.
• the fins 3 can be flat, smooth, corrugated or louvered and are usually aluminum.
• the stack of the fins 3 of the exchanger 1 has a length L.
• the fins 3 are perforated with holes 30 in order to let the tubes 2 pass. These holes 30 are aligned in several vertical rows 33 spaced a distance, corresponding to the not longitudinal PI of space between the tubes 2.
• the air passes through the exchanger 1 transversely in the direction of the arrow A.
• a refrigerant circulates in the tubes 2 from an inlet tube 20 and exits through an outlet tube 31
• This fluid can be for example of the water.
• the tubes 2 and the fins 3 must be in close contact to ensure good conduction. To guarantee this contact, an expansion tube is introduced into each tube 2 after it has been inserted into the fins to widen it and ensure better contact with said fins 3.
• the fins 3 must be spaced by a pitch Pa enough to let air circulate but not too important to avoid a loss of exchange (by-pass phenomenon).
• This pitch Pa must be identical between each fin 3 in order to have a uniform exchange.
• the pitch Pa of the fins 3 of the state of the art is such that under certain conditions of temperature and humidity of the frost can be formed the fins 3, it is then necessary to reverse the exchanger to heat the fins 3 and melt the frost. During this time, the room is no longer heated which causes inconvenience to the user.
• the exchanger 1 according to the invention illustrated in FIGS. 1 to 3, also has fins 3 and tubes 2.
• the fins 3 are pierced with holes 30 lined with flanges 31 and aligned in several rows 33. These flanges 31 have height Pa '> Pa.
• Two successive rows 33 are offset vertically relative to each other which gives flanges 31 staggered and which allows a better distribution of air.
• the holes 30 and the flanges 31 of a row 33 are regularly spaced.
• the number of holes 30 and flanges 31 are greater than the number of n tubes 2 of the exchanger 1.
• the tubes 2 together constitute a pin 22 and are inserted in two. These two tubes 2 are inserted in the main holes 300 of the same row 33, but with a free hole 301 intermediate them. There are therefore main flanges 310 traversed by a tube 2 and free flanges 311 not crossed by a tube 3.
• the tubes 2 are for example 50cm apart.
• a conventional heat exchanger will operate as shown in Figure 4.
• the outdoor temperature and humidity drop to a certain level for example, if the temperature is between -5 ° C and 2 ° C and the humidity at 85%, it will begin to frost, its heating capacity 4 gradually decreases 40 as frost sets in, so you have to switch on a defrost mode 5 to melt the frost.
• This defrosting mode 5 consists in reversing the operating mode of the exchanger 1 which will then heat the fins and this hot fluid will be missing in the room which will then be cooled.
• This mode has a disadvantage for the user, in order to limit it, it is possible to provide a buffer tank of about 3001 which allows the heating of the fins.
• the exchanger according to the invention illustrated in FIG. 5 has a heating capacity 4 which decreases twice as late as that of FIG. 4, here the offset is 1 hour, the operating time is therefore doubled with respect to exchanger of the state of the art and without the need for a buffer tank.
• the interval between two defrost is 130 minutes instead of one every 60 minutes.
• the table of FIG. 7 illustrates the time interval Dt between two defrostings as a function of the humid temperature of the air in contact with the exchanger.
• Curve A shows this gap with a heat exchanger of the state of the art and curve B that of the invention.
• curve B shows that if the absolute humidity of the air increases with the temperature, frost is formed around 0 ° C. Above 2 ° C, the temperature is too high for the water to frost and below -7 ° C, the air becomes too dry. The critical zone is around 0 ° C.
• the measurements below show that the invention makes it possible to significantly increase the time Dt between two defrosts.
• the heat exchanger can indifferently be used on an air conditioner or a heat pump without departing from the scope of the invention.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Geometry (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=62948213

Family Applications (1)

Country Status (3)

Family Cites Families (3)

• 2018
  • 2018-03-27 FR FR1852660A patent/FR3079604B1/fr active Active
• 2019
  • 2019-03-27 WO PCT/FR2019/050711 patent/WO2019186071A1/fr unknown
  • 2019-03-27 EP EP19719558.9A patent/EP3775750A1/de not_active Withdrawn

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