FR2642154A1 - Method for cooling a hot fluid using a cold fluid, without a common exchange surface in contact with these fluids, and exchanger for implementation thereof - Google Patents

Abstract

Exchanger and method for cooling a hot fluid using a cold fluid, characterised in that on either side of a separation plate 4, at least one set of small bars 5, 6 are arranged, which are joined to sets of plates 9, 10, themselves joined to frames 11, 12 connected to other plates 13, 14, in order to delimit at least one circuit for a vaporisable fluid, the said separating plate 4 having a plurality of sets of holes for establishing at least two independent circuits containing a vaporisable fluid.

Description

 The present invention relates to the cooling of fluids, in particular gaseous fluids, although it can be used in the same way for the cooling of liquid fluids, by means of a cooler fluid which must in no case be able to come into contact with the fluid - cool.

 The invention also applies to the heating of a cold fluid with a warmer fluid but which must not come into contact with the cold fluid.

 The invention finds applications and uses in different techniques. It relates in particular to the cooling, respectively the heating, of fluids - from polluted fluids or even the cooling, respectively the heating, of fluids which are very corrosive or which can be dangerous, as is encountered in the development of various products in the industry.

 In accordance with the invention, the process for cooling a hot fluid with a cold or reverse fluid without there being any heat exchange surfaces between the two fluids, process in which an intermediate fluid supplied A circulate in a closed conduit of which one strand is disposed in the hot fluid and another strand disposed in the cold fluid is characterized in that several plies of conduits are provided, each having a strand disposed in the hot fluid and a strand disposed in the cold fluid and in that said strands are isolated from the layers.

 The invention also extends an exchanger for implementing the above method.

 In accordance with this second arrangement of the invention, the exchanger for implementing the method is characterized in that there is on each side of a separation plate at least one set of bars connected to games of plates, themselves connected 2 of the connected frames - other plates! to delimit at least one circuit for a vaporizable fluid, said separation plate presented L several sets of holes for the establishment of at least two independent circuits containing a vaporizable fluid.

 Various other characteristics of the invention will also emerge from the detailed description which follows.

 Embodiments of the object of the invention are shown, by way of nonlimiting examples, in the accompanying drawing.

 Fig. 1 is a schematic perspective view of an intermediate fluid exchanger illustrating an arrangement known in the art but necessary 4 for understanding the invention.

 Fig. 2 is a curve showing a characteristic of the exchanger of FIG. 1.

 The fic. 3 is a schematic perspective of an exchanger implementing one of the aspects of the invention.

 The fic. 4 is a curve similar to FIG. 2 showing the characteristics of the exchanger of FIG. 3.

 The fic. 5 is a similar perspective - FIG. 3 of another arrangement of the exchanger.

 The fic. 6 is a front elevation of a plate-type exchanger implementing the invention and produced according to a particular arrangement of this invention.

Fig. 7 is a section taken along the line
VII-VII of fig. 6.

 Fig. 8 is an exploded but partial perspective of the exchanger of FIGS. 6 and 7.

 Fig. 9 is a perspective, analogous to the fia. 3 and 5, illustrating another arrangement of the exchanger at the same time as a different design thereof.

Fig. 10 is a section taken along the line
XX of fig. 8 while illustrating an additional feature.

 Fig. 11 is a similar section> FIG. 10 illustrating a variant.

 Fig. 12 is a section similar to FIG. 10 illustrating an additional feature.

 Fig. 13 is a section similar to FIG. 7 of a variant.

 To facilitate understanding of the process and of the embodiments of the exchanger for its implementation described in the following, reference is first made to FIG. 1 which illustrates a heat exchanger, generally designated by 1, of the type known in the art under the name "heat pipe" or "heat pipe".

 The heat pipe 1 comprises a conduit 2 closed on itself delimiting two strands 2a, 2b each provided with indirect exchanger elements 3, 3a having to be crossed one, the element 3, by cooling air (cold) illustrated by the arrows fl and the other by a fluid? cool (hot) illustrated by the arrows f2.

 The conduit 2 contains an intermediate heat transfer fluid which is chosen from the fluids capable of being condensed at the temperature of the cooling air and of being vaporized at the temperature of the air to be cooled.

 Fluids of this nature are well known in the art and most often consist of chlorine and fluorine compounds, for example tetrachlorofluoromethane constituting one of the fluids known under the trademark Freon.

 A heat pipe like the one briefly described above is usually arranged so that the exchange elements 3 and the strand 2a are at the top so that the strand 2b and the exchange element 3a are at the bottom, which allows the flow by gravity of the condensed fluid in the strand 2a towards the strand 2b.

If we denote by
- TEC the inlet temperature of the hot intermediate fluid in the strand 2a,
- TSC the outlet temperature of the hot intermediate fluid,
- TEF the inlet temperature of the cold or cooling fluid circulating according to the arrows fl and
- TEV the evaporation / condensation temperature of the intermediate fluid, we note the following with reference to fig. 1 and 2.

 The intermediate fluid evaporates in strand 2b and condenses in strand 2a at pressure pressure and temperature equal to TEA.

The efficiency of the heat exchange is defined by: t = TEC - TEV and it is maximum
TEC - TEF when 8 = 1, i.e. TSC = TEF.

In the case of the heat pipe in fig. 1, TSC cannot be less than 9 TEV. Consequently, the maximum efficiency which could only be achieved for an exchanger of infinite size is 8 MAX = TEC - TEV
TEC - TEF
Assuming that the heat flows of the coolant and the coolant are identical, the evaporation / condensation temperature TEV is
TUT = 1 (TEC + TEF)
2 and: # MAX = TEC - 0.5TEC - 0.5TEF
TEC - TEF
It thus appears that the use of a heat pipe according to FIG. 1 can only lead to a maximum efficiency of less than 0.5 under ideal conditions in which the coolant and coolant flow rates are the same. The efficiency of 0.5 is only achieved with sets exchangers of infinite size.

 According to the process of the invention, to improve the efficiency of the heat exchange, several condenser evaporators or independent evaporator / condenser layers illustrated in FIG. 3 by heat pipes I, II, III.

 Each heat pipe is made as illustrated in fig. 1 and their indirect exchange elements 3, 3a are arranged in series and are traversed in the same way as in FIG. 1 by the coolant according to the arrows fl and by the lie> cool according to the arrows f2.

 If we consider the direction of circulation of the fluid to be cooled, we note that it first crosses the evaporator I operating - the temperature TEV'1, then the evaporator II operating at the temperature TEV2 (TEV1 then l evaporator III operating the temperature TEV3 to TEV2 to TElTl, etc.

The taxman. 4 thus shows that it is possible to reach an outlet temperature for the fluid to cool.
TSC significantly lower than that obtainable by the heat pipe of fig. 1, the performance being improved by multiplying the number of layers I, II,
III ..., etc.

 In practice, there is thus a tendency towards the efficiency of a direct exchange, that is to say in which the two fluids are in contact with the same heat exchange surfaces and circulating against the current.

 The embodiment of the exchanger of fig. 3 of the heat pipe type but multiple plies makes it possible to have between the indirect exchange elements 3, 3a a separation plate 4 so that the coolant is completely isolated from the fluid to be cooled to allow for example the use of a polluted coolant or the cooling of a coolant 7 should not be mixed or brought into contact in any way with the coolant.

 Fig. 5 illustrates another arrangement according to which the plies I, II, III are no longer arranged in series as in FIG. 3 but stacked one above the other as illustrated in Ia, IIa and IIIa, the choice between the construction according to FIG. 3 and the construction according to FIG. 5 essentially depends on the space available for the installation of the exchanger. A combination of the two construction methods is also possible.

 To implement the process described above, the invention creates a new plate exchanger illustrated essentially in FIGS. 6 to 8 which makes it possible to use no external connection conduit for connecting the circulation strands 2a, 2b of FIGS. 1 and 3.

 In fig. 6 8 8 above, the separating plate 4 of the cooling fluid and of the fluid to be cooled constitutes one of the plates of the exchanger and is connected on each of its two faces = bars 5 respectively 6 between which are arranged heatsinks 7 respectively 8 preferably and in a known manner formed by wavy strips.

 ec bars 5, 6 are attached to plates 9, 10 on which frames 11, 12 are stacked. The frames 11, 12 are themselves covered by plates 13, 14.

As illustrated in the drawing
The frames 11, 12 define notches 13, 13a, 14, 14a opening towards the inside of the frame. The plates 9, 10 delimit holes 15, 15a respectively 16, 16a coinciding with the notches of the frames 11, 12.

The bars 5, 6 delimit holes 17, 17a, 18, 18a and a plate 4 of the holes 19, 19a which coincide with each other and with the notches of the frames 11, 12. On the other hand, the plates 13, 14 do not have any holes corresponding to the notches 13, 13a and notches 14, 14a of the frames 11, 12, so that the plate 4, the bars 5, 6, the plates 9, 10 and the frames 11, 12 define a circuit
I analogous to circuit I of FIG. 3 but entirely included in the stack described above without there being any external conduit.

 The bars 5, 6 and the dissipators 7, 8 delimit the indirect exchange elements for the passage of the cooling fluid and for the passage of the fluid to be cooled which must circulate on either side of the separation plate 4, while the intermediate fluid circulates inside the circuit I while being completely isolated from the cooling fluid and from the fluid to be cooled when the plates, bars and frames are joined together, of reference by brazing as is usual in an exchanger; plates.

 The drawing shows that circuit II is made in my own way by notches 131, 13la '141, 141a provided in frames 11 121 which correspond to plate holes and similar bars? those described in the foregoing but offset with respect to the notches and holes of the frames, plates and bars described in detail above.

 Fig. 6 shows that in the same way the sheet III is produced in a similar manner, always by stacking plates, bars and frames, the notches and holes of which coincide to form a circuit independent of the other circuits.

 After brazing, all of the plates, bars and frames constitute a monolithic whole, the internal circuits of which are independent, perfectly sealed with respect to each other while delimiting portions of condensation and evaporation also separated in a sealed manner by the plate 4 .

 The embodiment described in detail above with reference to FIGS. 6 n 8 corresponds -'.- a stacked sheet exchanger similar to that of the fi. 5. The same result would be obtained by assembling plate exchangers I, II, III in series as shown in FIG. 9, these exchangers delimiting, by their plates, bars and frames, each a circuit similar to the circuit illustrated in FIGS. 6 h 8 and corresponding, therefore, to the theoretical realization of fig. 3.

 Fig. 9 shows that the plate heat exchangers are separate but it could similarly be joined.

 In the above, only three layers I, II, III have been shown superimposed or successive. It is obvious that a different number of layers can be used.

 Fig. 10 shows that for am67-ozez thermal change, it is possible to have disturbing plates or other secondary heat exchange surfaces 20 in the frames such as 11, 12, 111, 121 ...

 Furthermore, the shape of the holes communicating the circuits delimiting the layers I, II, III ...

can be either circular as illustrated in fig. 10, or polygonal as illustrated in FIG. 11, or else the edges 21 of the holes, both of the frames and of the plates and bars, may have ribs and grooves (FIG. 12) promoting capillary flow of the intermediate fluid.

Fig. 13 illustrates a development of the invention according to which there are provided, for example, two half-exchangers A, B similar to that of FIGS. 6 n 8, these half-exchangers being arranged at a distance from the separating plate 4 and their corresponding internal circuits being connected by tubes 22 passing through the separating plate 4 in leaktight manner. The two tax exchangers. 13 can thus be arranged at a distance

<tb><SEP> that
<tb>'' one relative to the other pa exeny'e different speakers. In addition, it is possible to provide more than two exchangers.

 The invention is not limited to the exemplary embodiments, shown and described in detail, since various modifications can be made thereto without departing from its scope. In particular, filling tips are normally provided to give access to the various circuits containing the intermediate fluid. In particular, it is also possible that the plate 4 is fixed to frames instead of the bars described above, in particular with reference to FIGS. 6 to 8.

Claims (16)

 1 - Method for cooling a hot fluid with a cold fluid without there being a heat exchange surface between the two fluids in which an intermediate fluid is used which is brought to circulate in a closed conduit of which a strand is disposed in the hot fluid and another strand disposed in the cold fluid, characterized in that several plies of conduits are provided, each having at least one strand disposed in the hot fluid and at the bottom of the body spotted in the cold fluid.  2 - Process according to claim 1, characterized in that the strands in the hot fluid and the strands in the cold fluid are arranged in series.  3 - Method according to one of claims 1 and 2, characterized in that the strands placed in the hot fluid are superimposed as well as the strands placed in the cold fluid.  4 - Process according to ure of claims 1?. 3, characterized in that the strands arranged in the hot fluid are separated from the strands arranged in the cold fluid.  5 - An exchanger for implementing the method of one of claims 1 to 4, characterized in that there is on either side of a separation plate (4) at least one set of bars ( 5, 6) connected; sets of plates (9, 10), themselves reread? frames (11, 12) connected to other plates (13, 14) to delimit at least one circuit (I) for a vaporizable fluid, said separation plate (4) having several sets of. holes for reestablishing at least two independent circuits (II, III) containing a vaporizable fluid.  6 - Exchanger following the l-eler-dication 5, characterized in that the separation plate (4) is directly fixed between casings (5, 6) or frames (11, 12).  7 - Exchanger according to one of claims 5 and 6, characterized in that the plates (13, 14) closing the circuit (I) in turn support R other sets of bars, plates and frames having offset circulation holes compared to those of circuit (I) to delimit other independent circuits (II, III) themselves containing a vaporizable fluid.  8 - Exchanger according to claim 5, characterized in that the separation plate (4) supports several sets of bars, plates, frames and closing plates arranged in series.  9 - Exchanger according to one of claims 5 to 8, characterized in that the sets of bars (5, 6), plates (9, 10) and frames (11, 12) arranged in series on both sides other of the separation plate (4) are joined.  10 - Exchanger according to one of claims 5 to 8, characterized in that the sets of bars (5, 6), plates (o, 10) and frames (11, 12) arranged in series on both sides other of the separation plate (4) are separated.  11 - Exchanger according to one of claims 5 10, characterized by corrugated heatsinks (7, 8) disposed between the sets of bars (5, 6 ...).  12 - Exchanger according to one of claims 5 9 Z characterized in that the holes drilled in the frames (1), 12) communicate with the interior thereof by notches (13, 13a, 14, 14a).  13 - Exchanger according to one of claims 5 to 12, characterized in that the holes in the separation plates (4), bars (5, 6), plates (9, 10), frames (11, 12) ... have ribs and grooves.  14 - Exchanger according to one of claims 5 13, characterized in that the frames (11, 12) are provided with disturbing plates (20).  15 - Exchanger according to one of claims 5 14, characterized in that the separation plate (4), the bars (5; 6), the heatsinks (7), the plates (9, 10), the frames (11 , 12) and other plates (13, 14 and following) are assembled by brazing to form a monolithic whole.  16 - Exchanger according to one of claims 5 to 15, characterized in that at least two half-exchangers (A, B) are arranged ^ distance from each other on either side of the intermediate plate (4) and in that the circuits of said half-exchangers are connected by tubes ((22) passing through said intermediate plate (4) in a sealed manner.