GB1571723A

GB1571723A - Heat exchange devices

Info

Publication number: GB1571723A
Application number: GB609977A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1976-02-13
Filing date: 1977-02-14
Publication date: 1980-07-16
Also published as: FR2341120A1; DE2706195A1; BE851337A; FR2341120B1; DE2706195C2

Description

(54) IMPROVEMENTS RELATING TO HEAT EXCHANGE DEVICES (71) 1, PIERRE LAJOYE of 40 rue Charles de Gaulle, Montigny Les Metz (Moselle), France, a French Citizen do hereby declare the invention, for which I pray that a patent may be granted to me and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention concerns a heat exchange device, particularly suitable for carrying out heat exchange between fluids with or without mixing of the fluids, and to the heating or cooling or surfaces, e.g.

friction bearing surfaces. The invention is also concerned with the manufacture of such heat exchange devices.

In certain types of heat exchanger, there are tubes having a smooth cylindrical interior surface against which a first fluid circulates, and an exterior surface provided with fins against which a second fluid circulates. It is easy to increase the surface of contact of these tubes with the second fluid since all that has to be done is to provide vanes of greater size. On the other hand, it is difficult to increase the surface of contact with the first fluid, for example because of difficulties of manufacturing internal fins, if the tubes are of appreciable length. Hence there is very little versatility in the way in which the flow of the second fluid can be arranged to achieve the best possible exchange of heat.

The present invention has the principle aim of achieving a heat exchange device by means of which it is possible to bring about exchanges of heat between two circuits of fluid within an exchanger in which the construction permits considerable choice as to how the two circuits of fluid are arranged to interact.

In addition, the invention is applicable to the cooling of friction surfaces. The friction or the sliding of two surfaces one over the other generates heat, even if the coefficient of friction is well chosen, that is to say, if the coefficient of friction of the materials in contact is low, and if the nature of the surface of the rubbing faces is suitable produced.

This heating is lessened if: a) the contact pressures are low, b) the rubbing speeds are not very high, c) lubrication, carried out by a fluid agent, interposed between the rubbing parts, is well ensured.

d) the cooling of the rubbing parts is ensured, either by direct conduction or by the lubricating agent itself serving as a cooling agent.

In certain cases in which the parameters of the coefficient of friction are constant and maintained within certain limits (mainly of speed and pressure), a film of lubricating agent is interposed between the rubbing parts and then, remaining there by capilliary action or by hydrodynamic forces, it ensures sliding without appreciable wear, provided that the cooling is sufficient to maintain the temperature of the surfaces at a reasonable level. The materials in contact then retain their mechanical characteristics, in particular their reciprocal hardness.

However, when there are difficult friction conditions, as happens when the rubbing surfaces are subiect to heavy pressure or great speeds, to shocks, to jerks, to frequent stopping and starting, to reversals of direction, to cyclic or accidental stoppages, or if the surfaces must slide in an atmosphere which is hot, dusty or damp, in the presence of abrasive particles, etc., it is difficult, even sometimes impossible: a) to maintain the film of lubricating agent, b) to cool the surface of the rubbing components, that is to say the mass itself of these components.

It is then that seizures occur, because of the heating and a pinpoint fusion of the rubbing materials between which there is no longer the interposed film of lubricating agent, or because of blockages caused by the expansion of badly cooled moving components.

The present invention has therefore the equal aim of providing a heat exchange device by means of which it is possible to make well-cooled and well-lubricated bearings for large diameter shafts with heavy radial loads.

The invention provides a heat exchange device comprising a body having two opposite external faces arranged parallel to one another, a series of circular crosssection holes the longitudinal axes of which are perpendicular to the said two faces, each hole opening externally on at least one of the said two faces, a heat exchange unit located in each hole and forming therewith a chamber, and drillings in the body, the longitudinal axes of the drillings being substantially parallel to the said two faces, the drillings being arranged to interconnect the said chambers so that each chamber is in communication with at least one adjacent chamber so that a fluid may be passed through the drillings to enable heat exchange to take place between heat exchange units located in the said holes and the fluid passing radially through the said chambers.

The axes of the circular holes may be spaced regularly over the body with a distribution representing a series of equilateral triangles, each axis being at the apex of a theoretical triangle.

There may be at least two bodies each in the form of a flat plate, the plates being superposed one against the other in such a way that the holes correspond co-axially from one plate to another.

According to one preferred embodiment, the external surface of each heat exchange unit comprises a surface of revolution substantially in the shape of a diabolo from which external fins project into the chamber defined by the heat exchange unit and the hole in which it is located, the heat exchange unit also having an axially extending passage therethrough, internal fins projecting into this passage.

Each heat exchange unit may be formed by a portion of round tube to each axial end of which is welded a flange.

Alternatively each exchange unit may be defined between the flanges welded on the outside of a cylindrical tube, all the flanges of one series of coaxial units being welded to the same tube, which extends through the entire heat exchange device transversally in relation to the plates.

The axial peripheral ends of each heat exchange unit may be welded to the body of this unit by a ring of weld which seals off the space available between the exchange unit and its associated chamber from the exterior of the body.

Two consecutive units may be separated by a seal owing to which their internal cavities communicate with each other but are fluid-tight.

Two consecutive units may have exactly the same junction plane as two consecutive bodies, the units and the bodies having the same thickness and their respective parallel flat surfaces being machined then applied one against the other with an intermediate layer of joining paste.

Each heat exchange unit may be formed by a surface of revolution pierced by at least one hole, connecting an internal cavity of the unit to the chamber defined by the unit and the hole in which it is located, so as to bring about mixing of fluids circulating in the cavity and in the chamber respectively.

Two consecutive plates may be welded one against the other by a perpetual ring of weld forming a seal.

All the plates may be held together in a single rectangular block by means of bolts which pass through all the plates, each bolt being locked by a nut bearing on one outside plate, whilst its head bears on the other outside plate.

The block may comprise central plates each comprising a metal peripheral portion and a central plastics portion enclosing the exchange units, the central plates being sandwiched between outside plates entirely of metal, and the device being able to operate with circuits of fluid at high pressure.

Drillings provided in the thickness of the plates between the circular holes may be arranged so that a first fluid circulates in an internal cavity of each unit, whilst a second fluid, which circulates in the thickness of each plate in the said chambers, passes from one unit to the other following an overall zig-zag path in each plate before reaching the following plate and passing through it in the same way.

Preferably the first fluid which circulates in the internal cavities of the unit passes through each row of co-axial units before passing through the next row in the opposite direction, the overall path being in successive planes perpendicular to the planes of the plates, in such a way that the first and the second fluids circulate in opposite directions along their walls of thermal exchange inside each unit, the entry of the first fluid being located near to the outlet of the second fluid, and vice versa.

According to another preferred embodiment all the circular holes may be blind and open on the same face of the body to receive an exchange unit constituted by a plug carrying at least one groove which defines a chamber for the circulation of a fluid from one blind hole to another within the body, and a free rubbing surface.

Each plug may have at least one drilling which establishes communication between two different zones of the groove.

The plugs may each have a hole connecting the groove to the external axial face to provide a restricted leak of fluid, the fluid spreading on this external face to lubricate it.

Each plug may carry several successive grooves to increase the surface offered for thermal exchanges with the fluid circulating around the plugs.

Each plug may have a fixed peg which is engaged in a hole provided in the axial end of the associated chamber, in order to prevent the plug from revolving.

The external surface of the plug may carry a friction lining of a material different from that of the plug.

Each plug may have an 0 ring located in a groove provided near to the base of the plug to prevent any penetration of fluid between the bottom of the associated chamber and the base of the plug.

An elastic support may be interposed between the base of the plug and the bottom of the associated chamber, whilst the plug if fitted so as to slide axially within its blind hole.

The plug may be fitted to slide axially in its blind hole, and does not extend to the full depth of the blind holes, so that, according to the pressure of the fluid, each plug may either be retracted into its blind hole or may project from its body.

The upper groove of each plug may have on the side nearest to the external face of this plug, a generating line only slightly inclined in relation to the axis of the plug in order to increase the rigidity of the peripheral portion of said external surface.

Each plug may be constituted by at least two parallel plates or discs connected to each other by an intermediate diametrically tranverse wall, each wall face being opposite two openings drilled in the body parallel to the said two faces of the body, but leading respectively to the blind holes of the two consecutive plugs of the adjacent row.

Each plug may be permanently fixed and adjusted in its blind hole, whilst its free surface is machined in line with that of the body.

The space left between the line of the external faces of the projecting plugs and the external face of the body may be filled by a solid lubricating material constituted for example by agglomerated graphite.

The invention includes a process for manufacturing a heat exchange device according to the invention in which each heat exchange unit is defined between two flanges welded on the outside of a cylindrical tube, the method being characterised in that the device is assembled plate by plate, all the tubes being first placed in the first plate, and all the washers being welded to each plate before the following plate is introduced on to the tubes.

The invention also includes a process for manufacturing a heat exchange device according to the invention in which each exchange unit is constituted by a plug located in a blind circular hole in the body so that one external face of this plug projects in relation to the external face of the body so as to present a friction surface, characterised in that all the plugs are first locked against a fixed support in the body and then machined all together on their external surfaces, which project in relation to that face of the body on which blind holes open.

Where the plugs are able to slide axially each plug is temporarily held during machining by means of a rigid annular support placed between the bottom of the plug and the bottom of the associated blind hole, the plug being hence supported pressed against the support in the working position which it will occupy in service, if necessary a screw being engaged through the body and screwing into a hole tapped in the lower face of the plug, whilst once the machining is finished, the screw is removed, its sealing hole being blocked by a separate plug and the support removed.

By way of example, specific embodiments of the invention will now be described, with reference to the accompanying drawings, in which: Figure 1 is a face view of a body in the form of a plate, for a heat exchange device according to the invention Figure 2 is a section Il-lI (Figure 1); Figure 3 is a part section Il-Il (Figure 1) showing a heat exchange unit mounted in the plate; Figure 4 is a plan view of this unit; Figure 5 is a perspective view of this unit; Figure 6 is an overall perspective view of a plate Figure 7 is a plan view of this plate; Figure 8 is a view in vertical section showing one example of the use of this plate; Figure 9 is a perspective view of a heat exchange device comprising several plates; Figure 10 is a schematic perspective view to illustrate the operation of the device; Figure Il is a part section XI-XI (Figure 9); Figure 12 is a part section XI-XI (Figure 9) according to a variant; Figure 13 is a part section Xl-XI (Figure 9) according to another variant; Figure 14 is a section XI-Xl (Figure 9) according to another variant; Figure 15 is a schematic part plan view of the device Figure 9; Figure 16 to 19 are other part sections Xl-XI of the device in Figure 9; Figure 20 is a perspective part view of an exchanger tube of known type; Figure 21 is a schematic view intended to illustrate the operation, Figures 22 and 23 are diagrams showing the operation of the device in Figure 9, Figures 24 to 26 are other part sections XI--XI of the device in Figure 9 according to two variants, Figure 27 is an elevation of a heat exchange device according to another variant of the invention, Figure 28 is a plan view of an exchange unit according to another variant of the invention Figure 29 is a section XXIX--XXIX (Figure 28), Figures 30 to 32 are other part sections XI--XI of the device in Figure 9 according to other variants, Figure 33 is a part view in perspective of an exchange unit according to another variant, Figure 34 is a section XXXlV-XXXIV (Figure 33), Figure 35 is a plan view of a plate with plugs according to another variant of the invention, Figure 36 is a section XXXVI-XXXVI (Figure 35), Figure 37 is a schematic axial view of a bearing made by means of curved plates with plugs according to the invention, Figure 38 is a part plan view of Figure 35 according to a variant, Figure 39 is a section XXXIX--XXXIX (Figure 38), Figure 40 is a part view of Figure 35 according to another variant, Figure 41 is a section XLI--XLI (Figure 40), Figure 42 is a part plan view of Figure 35, according to another variant, Figure 43 is a section XLllI-XLlIl (Figure 42), Figure 44 is a part plan view of Figure 35 according to another variant, Figure 45 is a section XLV-XLV (Figure 44), Figure 46 is a part plan view of Figure 35 according to another variant, Figure 47 is a section XLVll-XLVll (Figure 46), Figures 48 to 53 are axial sections of units or plugs according to different variants, Figure 54 is a part plan view of Figure 35 according to another variant Figure 55 is a section LV--LV (Figure 54), Figures 56 to 58 are axial sections of units or plugs according to other variants, Figure 59 is a part view on an enlarged scale of Figure 58, Figure 60 is an axial section of another unit or plug according to a variant, Figure 61 is another axial section illustrating the process for machining the same plug, Figure 62 is a section XXXVI-XXXVI (Figure 35) according to another variant, Figure 63 is a view identical to Figure 62, illustrating another phase of operation, Figure 64 is a view identical to Figure 35, according to another variant, Figure 65 and 66 are part sections LXV LXV (Figure 64).

There is shown in Figures 1 and 2 part of a body in the form of a plate 1 (Figure 6) in which a series of holes 2 is drilled transversely from side to side. The axes of these holes are distributed so as to represent a series of equilateral triangles, in such a way that a distance 3 always separates the edges of two adjacent holes.

The holes contain exchange units 4 (Figures 3 to 5) which are cylindrical, this form being naturally that which allows the easiest assembly for machining. The holes 2 and exchange unit 4 co-operate to define chambers 6. The chambers 6 communicate one with another via holes such as 5, generally drilled, of which the axis for preference coincides with the line which joins the centres of two consecutive units 4 when fitted in place, to allow a fluid agent to circulate from one chamber to another within the plate.

Each unit 4 essentially comprises a surface of revolution 7 in the shape of a diabolo from which project external fins 8 and internal fins 9. An internal compartment which is defined between the fins 9 inside the unit extends axially throughout this unit, of which the height is closely the same as the thickness 10 of a plate. At each axial end of the unit the periphery of the surface 7 is welded to the edges of the hole 2 by a ring of weld 11 to form seal.

The plate I, considered as a whole, may be traversed by a first fluid following the arrow 13 (Figure 6) perpendicularly to its large faces, and by a second fluid, following the arrow 12, within the thickness of the plate. The fluid 12 can circulate in various ways in the plate, either in parallel flows passing individually through each row of units 4 or in a single flow passing successively through each row by making a half-turn at the end of each row (Figure 7).

In each case however the fluid 12 passes radially through the chambers 6.

If such a plate is immersed vertically in a container holding a fluid so as to separate the said container into two parts 14 and 15 (Figure 8) a current of fluid passes through the units of the plate without communicating with the current of fluid circulating within the thickness of the plate, and a simple heat exchanger is thus obtained.

A more rational exchanger may be constructed by stacking one on top of another several identical plates fitted with appropriate units (Figure 9). Square, rectangular or, if needed, even circular plates are placed in contact with one another so that the axes of the units coincide and are attached so as to form a simple cubic or parallelipipedic block.

This attachment may be carried out welding each plate to the next (Figures 24 and 25). Two consecutive plates are then linked by a ring of weld around the periphery 16 (Figure 25) which is attached to the plates by means of zones 17 of material fused by the penetration of the weld. A peripheral groove 18 may be provided at a certain distance from the edge to avoid any crack in the weld at the level of the junction of two plates.

This attachment may also be carried out by strips 19 which cover the joints of the plates. The strips 19 are then welded to the edges of the plates (Figure 26).

In both cases, almost the whole of the surface of the plates may be taken up by the seating holes of the units 4. In the case of exchangers for high pressure circuits, it is necessary that the plates be joined to each other by threaded clamp bolts 20, the ends of which carry clamping nuts 21 (Figure 27).

All the peripheral part of the plates is then used for clamping, whilst the central part constitutes the exchanger proper. The thickness of the outside plates 22 and 23 as well as the distance 24 between the part containing the units 4 and the outside edges of the plates depend on the pressures within the exchanger. If necessary, the assembly may be further reinforced by central clamps. It will naturally be necessary to provide a sealing joint all around the plates.

When the machining of the plates is very smooth they alone ensure sealing through the contact of the surfaces. For preference, O rings are used, each fitted between two plates on a groove parallel to the external edge of the plates, or a paste joint spread on assembly between each two plates.

It will be seen then that the units, introduced into circular holes drilled in each plate in a fixed pattern allow an exchange of heat between two crossing fluids. A first fluid passes in the central part or channel 25 of each unit, whilst a second fluid passes between the wall 7 of the unit and the wall of the hole 2, the different holes 2 communicating with one another by means of holes, parallel to the large faces of the plates. The second fluid thus passes through the chamber 6 around each unit, then the next, ect. until it finally leaves the plate either by an opening 27 drilled in the edge of the plate or through a special header unit to reach the next plate. The first fluid similarly passes through the channel 25 of all the coaxial units in one row until it finally either leaves the exchanger by the axial opening of the unit in the last plate or else on reaching the last plate of the exchanger it is directed by a special header unit in this last plate so as to continue in the opposite direction in the channel 25 of the next row.

There is shown schematically in Figure 15 the circulation of the second fluid near to one edge of the plate. It will be seen that the last holes 28 and 29 have a connecting hole 30 which allows the fluid to pass from one row of holes to the other following an overall plane sinuous path (Figure 7).

In Figure 10 this circulation of the second fluid is shown by dotted lines 31.

The special header unit shown in Figure 19 carries a passage 32 through which the first fluid may divert, or turn back into the exchanger by passing from one row of units to another. This path may likewise be ensured by means of a special supplementary plate 33, placed at the end of the stack of plates (Figure 16).

The circulation of the first fluid is shown in full lines in Figure 10.

It is evident that all kinds of circuits may be envisaged in relation to the particular heat exchangers which it is desired to obtain. In a case where special circuits are necessary a special part may be used such as, for example, part 35 in Figure 17, as a replacement for several superposed units 4, so that the second fluid which is circulating within one plate leaves it to begin circulating in another plate.

In Figure 18 a part 36 is shown, which allows the second fluid passing normally around the units, to circulate in the central channel of the units in place of the first fluid, or co-jointly with this first fluid, as required. Such an arrangement may be used where, in addition to bringing about heat exchange between two fluids, it is desired to mix the fluids, or a proportion of the fluids.

It may also be used where heat is exchanged not from one fluid to another, but from fluids flowing in the passages to the exchange units 4 themselves, either to heat up the units 4 or cool them down.

In addition, several variants may be used to ensure sealing between the circuits of the first and second fluids, by replacing the ring of weld 11 in Figure 3, the advantage of which is mainly to avoid in all circumstances any mixing between the two circuits, even if the plates join badly to each other.

Following a first variant illustrated in Figure 11, each unit is inserted between two seals 37 of metalloplastic or 0 ring type which project into a recess 38 machined around the circular hole 2, on each side of the plate. In this way sealing is obtained between the units and the plates, and between the plates themselves.

According to another variant shown in Figure 12, the units are fitted in the plates and the plates are sealed between themselves either by seals around their edges or by individual seals placed around each unit or by a single 0 ring 39 placed between two units.

Figure 13 shows a unit of which the height 14 is equal to the thickness of the plate. The stacking of the plates may then ensure sufficient sealing in the machining is correctly carried out, or if a plastic paste seal is spread on the two opposite faces of the plates before assembly.

If it is permissible that a slight leak may occur from one circuit to another, absolute sealing is of no great importance (for example, in the case of cooling fresh water by fresh water). In the case of an exchanger made from mild steel which contains fresh water all the joints are quickly blocked by rust.

In Figure 14 a unit 41 welded into its seating is shown. Sealing is ensured by a seal 42 placed between the two units in a gap allowed inside the weld.

The operation of the exchanger is as follows.

It is known that to obtain an effective heat exchange between two fluids it is necessary that the difference in temperature between the fluids be as great as possible throughout the duration of the exchange. If fluids A and B circulate along parallel paths and in the same direction in an exchanger, temperatures taken along the common path evolve according to the curves 43 and 44 of Figure 22. On the other hand, if the fluids circulate along parallel paths but in opposite directions, the temperatures evolve according to curves 45 and 46 of Figure 23, which allows a better heat exchange.

However, if in most cases efforts are made to bring about the second condition, it may be advantageous in some cases, to bring about the first, in that the various parts of the exchanger itself are at closely constant temperatures, which avoids geometrical distortion due to expansion.

The circulation diagram which has been described above in conjunction with Figure 10 constitutes two circulations following plane sinuous paths which allow the circuits to cross over each other.

There are thus two circuits of which the respective individual networks 31 and 34 are perpendicular to each other, but form layers respectively parallel to the faces of the parallelipiped, going towards each other to cross over in the central part of the block.

One of the advantages of the exchanger made in this way resides in that the two circuits of fluid may be in contact with the fins and so benefit from a larger exchange surface. It is known that in certain existing exchangers using profiled tubes of great length such as tube 47 of Figure 20, the fluid which passes inside the tube cannot benefit from a large exchange surface owing to the technical difficulty of manufacturing fins or other additional heat transfer surfaces inside the tubes.

It will be noticed in addition that in the embodiment according to the invention the circuit of the first fluid undergoes a succession of constrictions and expansions while passing through the successive channels 25 of the unit (Figure 21), which is favourable to exchanges of temperature by friction on the walls.

This succession of widenings and narrowings is also true with respect to the circuit of the second fluid, and it may be utilised to homogenise a mixture of two fluids circulating in the same cavities, which may be achieved using unit 36 of Figure 18.

Part 36 may also be placed instead of two consecutive units in the same plate when their internal circuits communicate to cause a circuit in the central channel 25 to change its direction in the same way as in Figure 16.

Placed one above the other parts 36 may replace the part 35 on the left of Figure 17.

Naturally, the plates and the units are made of a material, metal or alloy, suitable for the demands of termperature and pressure of the fluids present. The material which constitutes them must likewise, if necessary, resist corrosion in these fluids.

The units 4 must resist the corrosion of both fluids, whilst the plates, if the seals between the units are well made, may only have to resist the corrosion of the fluid which circulates around the units.

Plates of plastics material may be used in so far as the temperature of the hotter fluid is sufficiently low as not to affect the material.

It is advantageous to make the plates from plastics or other material of low thermal conductivity, thus reducing the dissipation of heat in the material of the plates.

The units 4 are, on the other hand, preferably made from a material of high conductivity, for example from copper or aluminium alloys.

If the manufactured equipment must be capable of resisting temperatures acceptable to a plastics material, but pressures too high for the material, the central plates may be made of plastics material and enclosed between metal plates 22 and 23 (Figure 27). If necessary only that part of each central plate which houses the units 4 may be of plastics material, the peripheral part of each central plate being made from a resilient metal or alloy. Thus all exposed faces of the arrangement shown in Figure 27 would be made of metal.

The exchanger block may likewise be made by replacing the plates by a block in one piece in the form of a parallelipiped, drilled with parallel holes of a diameter equal to that of the units, and perpendicular holes spaced at the height of a unit increased by that of a seal. The units are then threaded in line in the first holes. In this way, to the detriment of the ease of machining and with necessity of providing numerous threaded plugs to close off unwanted open ends of drillings, it is possible to use higher pressures without having to use seals between the plates. It becomes, on the other hand, difficult to combine complex circuits with special units as may be done with stacks of plates.

As a variant, a unit 4 may be made in the form of a portion of tube 50 (Figure 30), to which are welded external flanges 51 at the two axial ends. A tube unit 52 may likewise constitute a unit 4 (Figure 31), if external fins are machined on this unit.

A series of coaxial units 4 may likewise be replaced by long tubes 54 to which are welded spaced external flanges 55. Each flange 55 corresponds to one plate thickness, and ensures sufficient sealing between the different channels of the circuit of the second fluid (Figure 32).

As opposed to a conventional tube exchanger, this exchanger allows complete control of the fluid circulating within the plates, parallel to their large faces and external to the tubes. A high pressure exchanger may be made more easily, and heat may be easily transferred to a fluid, the heat for example arising from solid material contained in the tube.

The exchanger may be assembled plate by plate by fitting from the beginning all the tubes to the first plate and by welding each time all the flanges 55 on the one hand to the tubes and on the other hand to the appropriate plate; this system presents the double advantage of ensuring perfect sealing between the internal circuits of the plates whilst immobilising the tubes and thus reducing the likelihood that expansion will cause them to buckle.

According to a variant illustrated in Figures 28 and 29, the units 4 are replaced by units 56, the walls 7 of which do not carry fins but are drilled with one or several small holes 57 through which the second fluid may squirt into the circuit of the first fluid in the channel 25. If these holes are inclined in relation to the radii of the unit, the mixture is caused to revolve about its axis in the channel 25. This movement allows the mixture to be homogenised when combined with the successive expansions and compressions caused by the shape of each channel 25.

If one unit, or a series of successive units, makes the current turn in one direction, the following unit, or the following series of units, will, for preference, turn the current in the opposite direction through an opposite inclination of the holes 57 in order to improve the mixing.

This arrangement allows a mixer to be obtained which will bring about extremely close mixing of two gaseous liquid or viscous fluids. The respective pressures of the two circuits may be varied to modify the proportions of the mixture.

The fluid which circulates in the grooves or between the external fins of the units may be fluent solid in the form of a paste forced into the circuit, for example by a plasticising machine.

It will be seen that the exchanger block may likewise be used as a reactor, since it allows a liquid component to be introduced in a homogeneous way into another liquid with which it reacts to produce a chemical combination, or to introduce one gas into another gas, or else a liquid into a current of gas or a gas into a current of liquid, or again, a solid in paste form into a liquid.

This introduction may, in addition, be made at the very high pressures which are sometimes necessary for chemical reactions to take place, and it is possible in all cases to control with precision the output of each of the components which must react in a definite proportion.

Part of the apparatus, before the exchanger reaction, may be used to raise or lower the temperature of one of the components in relation to the other before the reaction, by means of appropriate heat exchange and this may be done with an auxiliary fluid for each of the two reagents, which allows, for example, a paste to be fluidised, or the component reagents to be brought to the temperature the most suited to the reaction. In fact, the device described lends itself to all possibilities, and this with standard units; units with fins for exchanges.

special units for changes in direction, smooth units with openings for mixtures and reactions.

It is particularly interesting to use units of plastics material, as has been said above, in the case of an apparatus used as a mixer or as a reactor at low or medium temperature, if metallic material are unsuitable for reasons of corrosion.

Following another variant of the invention, the apparatus may be used as a tubular boiler by passing hot comstion gas through the central channels 25 of the units, whilst cold water is admitted to the interior circuit of the plates in order to emerge hot.

In all cases the exchanger, mixer or reactor apparatus has no limit in size, since it is possible to add to it any number of additional standard plates required.

According to a variant illustrated principally in Figures 35 and 36, the plate I is replaced by a plate 58 drilled with blind holes 59 in one of its large faces. Each hole 59 receives a plug 60 which is generally deeper than the hole so as to project beyond the face 61 of the plate 58. The holes 59 and the peripheral grooves 62 of the plugs 60 define compartments 63 which can communicate with one another through holes 64 drilled parallel to the faces of the plates as for plates 1.

The juxtaposition of the upper faces 65 of the plugs 60 constitute a friction bearing surface for a body 66 which is moving over the plate 58. This friction bearing surface may be flat as in Figure 36, but it may likewise be cylindrical, as is partly shown in Figure 37, or again spherical or conical.

By making a fluid circulate from one chamber 63 another, by means of the holes 64, it is possible to establish a current of cooling fluid from main openings situated for example at the end of the line of a series of plugs. This flow of fluid is able to pass through a certain number of consecutive plugs before leaving the friction compartment, or to pass through a new line of plugs after being deflected in the thickness of the plate 58.

Certain plugs may act as distributors.

Thus the plug 67 in Figure 38 is located in a hole into which four communication holes 64 open. The section of the groove around the plug 67 (Figure 39) is calculated in relation to the distribution output required.

A transverse hole 68 (Figures 40 and 41) or two parallel transverse holes 69 (Figures 42 and 43) may be provided in a plug, in order to allow all or part of the cooling fluid to pass through this plug. The holes 68 and 69 open either into the circular groove or grooves of the plugs. They may open into the groove or grooves directly opposite the communication holes 64.

Naturally the cooling may be modified so as to be concentrated particularly on certain plugs more subject to pressure from the rubbing component 66, which is produced particularly in the case of bearings. So as to enhance the cooling of certain plugs the diameters of the communication holes 64 which connect the chambers 63 may be varied, as may be the section of the grooves in the plugs; these diameters and this section will be larger in the zones which concern the privileged plugs.

The contact surface between the plug and the cooling fluid may also be increased by using plugs with double grooves (Figure 49) or multiple grooves 70 (Figure 56). In all cases, the section of the holes 59 may remain the same overall.

The circuit of fluid may naturally be fed at a variable pressure controlled by an adjustable pressure reducer placed at the outlet from the device.

Each individual plug may be lubricated by drilling one or two channels 71 (Figures 44 and 47) allowing the compartment 63 to communicate with the friction surface of the plug, so as to bring to it the fluid which is chosen to have lubricating properties.

The size of the grooves 71 is calculated in relation to the pressure in the circuit, and the pressure of friction to ensure an adequate film of lubricant on each individual plug. The opening of each channel is designed to facilitate the establishment and the conservation of the film of lubricant, or the maintenance of a patch of lubricant.

By closing more or less completely the outlet openings from the plugs of the underlying lubricant circuit, the main role of the fluid may be limited to that of a lubricating agent, or the outlet of the same fluid may be proportioned at will so that the fluid will serve both as lubricating agent and cooling agent.

Given that the friction surface of the plug projects above that of the support, and that the plugs are not in contact with one another, there remains when the moving part is in place a series of closed cavities communicating with each other, which affect part of the surface. It is into this volume that the lubricating fluid arriving at the surface of each plug will pour to constitute the film of lubricant.

Therefore if solid impurities are introduced inadvertently into this system: they have room to remain in this free space 72 (Figures 35 and 36) between the moving surface and the surface of the support instead of becoming inserted between the two surfaces in contact which would have the effect of damaging the said surfaces, they are carried by the excess of lubricating fluid which bears them to a filter where they are held.

In the particular case in which the plugs are cylindrical and uniformly distributed in a pattern of equilateral triangles, the residual surface not covered by the plugs is equal to: 4/4(d+E)22/8d2 where E is the distance from edge to edge of the plugs and d their diameter.

As an indication, if E=O, the plugs are touching and the surface between the plugs represents 10.50/, of the total surface.

If the distance between plugs represents 0.05 d, the relationship surface of the spaces to surface of the plugs is approximately equal to 20% The projection of the plugs and the distance between plugs may be varied so that the return circuit of the lubricating agent coming to the plug surface may be under pressure or on the contrary may flow freely in this cavity.

The material employed for the manufacture of the plugs must possess the following qualities:- good resistance to compression, at least sufficient for their projecting portion not to crush; an elasticity sufficiently good for the plugs to be able to absorb machining irregularities, even minimal, in the moving component; a low coefficient of friction with the material of the contacting moving part; a thermal conductivity as great as possible.

The plugs may be composite, and include an upper part 73 of special material (such as an antifriction alloy), the rest of the body being made from a very good conducting material which is also resistant, such as copper 4/4 hard, chrome copper, beryllium copper, etc. (Figures 52 and 53).

Figures 48 to 58 show the different shapes of plug which may be made, following several variants, in the case of cylindrical plugs.

The plug in Figure 48 is the simple plug 60 with an external groove 62.

The plug 74 in Figure 49 includes two grooves, of which the total section is equal to that of the groove 62. The two holes 75, drilled diametrically in these grooves, have a section equivalent to that of the grooves.

The plug 76 in Figure 50 has an outlet hole 77. the shape of which is designed so as to facilitate the introduction of the individual film of lubricant, by drawing it from the cooling circuit. The dissymmetry arises from the direction of sliding.

The plug 78 in Figure 51 has an opening 79 in the shape of a funnel which opens on the one hand in the centre of the rubbing surface, and on the other in a transverse hole drilled in the plug.

The plug 80 in Figure 53 has a hole 81 for lubrication combined with an upper part 73 of special material, hence it is composite, cooled and lubricated, whilst the plug in Figure 52 is not lubricated.

The plug 82 in Figure 55 carries a safety peg 83. This peg is located in a hole provided in the plate 58, to prevent the plug 82 from turning (Figure 56) under the effect of friction.

The plug 70 in Figure 56, already mentioned, has the disadvantage of being less rigid around its periphery which is not as thick. There is shown in Figure 57 a plug, the groove 84 of which is, on the other hand, specially designed so that the periphery of the upper part shall be as thick as possible, and hence as rigid as possible, owing to an upper curve not so much inclined to the axis as the curve of say the plug of Figure 52.

All the plugs described so far are intended to be sealed into the blind holes 59 into which they are fitted.

The penetration of cooling and lubricating fluid below the plug may be prevented by providing around each plug an O ring 85 located in a groove 86 (Figures 58 and 59) in the lower part of the plug. Thus, in the case in which the sealing may be discontinuous, it is possible to avoid the plug tending to leave its hole or to exercise a greater pressure than the other plugs on the moving component 66 (Figure 36).

The plugs are manufactured in the following manner: They are first machined, their upper faces remaining rough, then they are pressed into their seatings with an initial tightness which holds them immobile, and they are sealed to the bottom of their blind hole with an adhesive product such as Araldite, Loctite, etc.

The plugs once assembled are all machined together so that their rubbing surface is suited to the shape of the moving component, whether this shape is cylindrical, spherical, conical, or simply flat.

The surface of the support is generally parallel to that of the rubbing component, so that the clearance remains more or less constant between the moving component 66 and the plate 58.

It is possible, according to a variant, to vary the distance which separates the surface of the support from the rubbing surface (Figure 37), by restricting the return flow of the lubricant at certain points causing a build up of pressure, and by permitting a free return flow in other places.

The same result may be obtained by reducing the diameter of the plugs in certain places, without changing the projection of these plugs in relation to the support. This operates, however, to the detriment of the density of the rubbing surface, owing to the reduction of the said diameter.

This system is suited to numerous variants, some of which will be described by way of example.

According to a first variant of this system, each plug 87 is fitted so as to slide axially in its blind hole (Figure 60) and an elastic support 88 is placed between the bottom 89 of the blind hole and the bottom of the plug.

The contacting moving part 66 has the benefit of a small degree of liberty, whether it be flat or cylindrical, to the detriment of the rigidity of the assembly. In this case, it is absolutely necessary to fit an 0 ring 85 at the base of the plug (Figure 59) if it is desired that the plugs be individually lubricated.

According to a second variant of the said system, all the plugs which are fed by a circuit of oil at the same pressure may be transformed into individual lacks acting collectively, by feeding pressurised fluid through radial drilling (not shown) into chambers located between the lower face of the plugs and the bottom of the blind holes.

Proiections 89a prevent the volume of the chambers from being reduced to zero. They must then be fitted with one or several 0 rings in their upper part (Figures 62 and 63) in order to prevent the pressurised fluid from escaping to the level of the surface of the support, whilst the lateral surface of the seating is lapped. In this case, all the plugs are not lubricated individually for fear of reducing or diminishing control of the operating pressure.

This device will be used if it is necessary for example to cause the nat sliding of a moving part 90, or to cause it to stop, on a surface. The plugs are then either completely retracted (Figure 62), the moving part 90 then coming to rest on the support. or extended (Figure 63) to raise the moving part 90 and allow it to slide. The fluid also removes from the plugs any heat generated by the sliding action.

In this case, as in the case of the variant illustrated in Figure 61, a rigid annular support 91 is placed in the bottom of the cavity to allow the plug to rest rigidly on its lower face for machining in the working position which it will later occupy. Once the machining is finished, the supports are removed, either to be replaced by the elastic support or to allow the hydraulic fluid to circulate freely. If it is necessary to hold the plugs pressed against this support during machining, use is made of a screw passing through the support and screwing it into a hole tapped in the lower face of the plug.

Once the machining is finished, the locating holes of the screws are blocked by separate plugs.

According to another variant of the same system, the support is a smooth bearing when all the plugs are retracted, and the extension of the plugs causes the braking of a moving shaft. In this case, the plugs are made from a material with a high coefficient of friction. A bearing may likewise comprise only a single circular line of braking plugs, all the other plugs being used for sliding.

According to another variant, the cooling and/or lubricating fluid is a more or less viscous liquid (for example, oil), a gas, the vapour of a liquid, or a metallic liquid (for example, mercury or liquid sodium). It may likewise be a gas charged with solid particles with a very low coefficient of dry friction.

According to another variant, the circuit established around or in the plugs and in the support may be followed by a hot fluid in order to bring the assembly to a required temperature.

According to another variant, the geometrical shape formed by the grooved plugs and the blind holes may be considered only as a means of having a rigid volume traversed in a controlled manner by a cooling or heating current. The plugs are then welded to form a seal, or else secured by adhesive, screwed, etc. By machining the surface of the plugs and the support, each constituted by the same metal, or by different metals, at the same time, it is possible to manufacture for example a plate, a pad, or some sliding bearing which is entirely heated or cooled. The section of the passageway which may be considerably increased, is only limited by the maximum surface of the hole which may be drilled between two adjacent plugs. A conformation such as that shown in Figures 64 and 65, by using the plugs of two consecutive rows alternately allows a controlled circulation of very large section to be achieved.

In this case, the plugs are slotted on each side by two parallel grooves 92, that is to say they each comprise two flat parallel discs connected to each other by a transverse diametrical wall 93. Owing to the variation in the angular position of these plugs, precisely directed circuits may be achieved in a solid from its surface or surfaces, by simple drilling.

Each plug may carry two pairs of grooves 94 instead of the groove 92 (Figure 66), which allows an outward circuit of the heating or cooling fluid under one of the faces and a return circuit under the other to be achieved in a solid with two parallel faces close to each other.

According to another variant of the invention, the space left free between projecting plugs is packed with a material different from that of the plugs.

This material is a solid lubricant generally constituted by agglomerated graphite which is introduced through wear in case normal lubrication ceases; for example, because of an occasional non-instantaneous overload, or of a breakdown in the lubrication circuit.

It is a known practice to place in rubbing surfaces such as those of bearings or slideways inserts of this type. These inserts are generally in the form of circular plugs, bands transversal to the direction of sliding, or spiral bands.

The arrangement already described of friction plugs in an equilateral triangular pattern gives these inserts an additional advantage; rubbing can occur in any direction and still bring a solid lubricant to the rubbing surface as soon as the latter begins to wear. On the other hand, these inserts may be used with plugs which are only cooled and a conventional greasing or with cooled plugs with a lubricated surface.

According to another variant, a sliding surface may be machined simply to produce hollows having the shape of the interstices between circular plugs arranged in an equilateral triangle pattern, and then these hollows filled with solid lubricant.

The support of the plugs will generally be chosen from materials which are cheap and easy to machine, as well as being nonporous.

Laminated or forged steel is one of the most economic materials which is suitable.

However, it may be necessary for the support to be immune to rust, if, for example, the thermal exchanges are carried out by water. A rough cast support, for example chill-cast, may be equally suitable.

If salt water is to be used, special cuproaluminium with iron and nickel, or cupronickel would be used for preference.

In cases where heavy wear liable to destroy the plugs is feared, the support is in a bearing alloy (for example, bronze or lead), to ensure trouble-free sliding.

For reasons of weight, a support made of light alloy may be used.

The plugs may be made of bearing plastics material. In this case, the underlying circuit serves to lubricate the rubbing surfaces, and also to cool the support, hence the return fluid running on it and the spaces between the plugs are of the greatest use in preventing impurities from penetrating into the plastics friction material.

According to a final variant, a fluid bearing may be provided using high pressure of fluid linked to the central and individual oil-flows in the plugs. Before being set in motion, the moving component is raised from the rubbing component by cushions of lubricant on each plug. A cushion of oil may be used, for example.

WHAT I CLAIM IS: 1. A heat exchange device comprising a body having two opposite external faces arranged parallel to one another, a series of circular cross-section holes the longitudinal axes of which are perpendicular to the said two faces, each hole opening externally on at least one of the said two faces, a heat exchange unit located in each hole and forming therewith a chamber, and drillings in the body, the longitudinal axes of the drillings being substantially parallel to the said two faces, the drillings being arranged to interconnect the said chambers so that each chamber is in communication with at least one adjacent chamber so that a fluid may be passed through the drillings to enable heat exchange to take place between heat exchange units located in the said holes and the fluid passing radially through the said chambers.

2. A device according to claim 1, in which the circular holes are not touching, their respective axes being arranged in a pattern of equilateral triangles.

3. A device according to either claim 1 or claim 2, in which at least two bodies, each in the form of flat plates, are superposed one against the other in such a way that the holes correspond co-axially from one plate to the other.

4. A device according to any one of the preceding claims, in which the external surface of each heat exchange unit comprises a surface of revolution substantially in the shape of a diabolo from which external fins project into the chamber defined by the heat exchange unit and the hole in which it is located, the heat exchange unit also having an axially extending passage therethrough, internal fins projecting into this passage.

5. A device according to any one of claims I to 3, in which each heat exchange unit is formed by a portion of round tube to each axial end of which is welded an external flange.

6. A device according to claim 3, in which each heat exchange unit is defined between two flanges welded on the outside of a cylindrical tube, all the flanges of one series of coaxial units being welded to the same tube, which extends through the entire heat exchange device transversally in relation to the plates.

7. A device according to any one of claims 4 to 6, in which the axial peripheral ends of each heat exchange unit are welded to the body of this unit by a ring of weld which seals off the space available between the exchange unit and its associated chamber from the exterior of the body.

8. A device according to any one of claims 4 to 6, in which two consecutive units are separated by a seal owing to which their internal cavities communicate with each other but are fluid-tight.

9. A device according to any one of Claims 4 to 6, in which two consecutive

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Claims

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an occasional non-instantaneous overload, or of a breakdown in the lubrication circuit.

It is a known practice to place in rubbing surfaces such as those of bearings or slideways inserts of this type. These inserts are generally in the form of circular plugs, bands transversal to the direction of sliding, or spiral bands.

The arrangement already described of friction plugs in an equilateral triangular pattern gives these inserts an additional advantage; rubbing can occur in any direction and still bring a solid lubricant to the rubbing surface as soon as the latter begins to wear. On the other hand, these inserts may be used with plugs which are only cooled and a conventional greasing or with cooled plugs with a lubricated surface.

According to another variant, a sliding surface may be machined simply to produce hollows having the shape of the interstices between circular plugs arranged in an equilateral triangle pattern, and then these hollows filled with solid lubricant.

The support of the plugs will generally be chosen from materials which are cheap and easy to machine, as well as being nonporous.

Laminated or forged steel is one of the most economic materials which is suitable.

However, it may be necessary for the support to be immune to rust, if, for example, the thermal exchanges are carried out by water. A rough cast support, for example chill-cast, may be equally suitable.

If salt water is to be used, special cuproaluminium with iron and nickel, or cupronickel would be used for preference.

In cases where heavy wear liable to destroy the plugs is feared, the support is in a bearing alloy (for example, bronze or lead), to ensure trouble-free sliding.

For reasons of weight, a support made of light alloy may be used.

The plugs may be made of bearing plastics material. In this case, the underlying circuit serves to lubricate the rubbing surfaces, and also to cool the support, hence the return fluid running on it and the spaces between the plugs are of the greatest use in preventing impurities from penetrating into the plastics friction material.

According to a final variant, a fluid bearing may be provided using high pressure of fluid linked to the central and individual oil-flows in the plugs. Before being set in motion, the moving component is raised from the rubbing component by cushions of lubricant on each plug. A cushion of oil may be used, for example.

WHAT I CLAIM IS: 1. A heat exchange device comprising a body having two opposite external faces arranged parallel to one another, a series of circular cross-section holes the longitudinal axes of which are perpendicular to the said two faces, each hole opening externally on at least one of the said two faces, a heat exchange unit located in each hole and forming therewith a chamber, and drillings in the body, the longitudinal axes of the drillings being substantially parallel to the said two faces, the drillings being arranged to interconnect the said chambers so that each chamber is in communication with at least one adjacent chamber so that a fluid may be passed through the drillings to enable heat exchange to take place between heat exchange units located in the said holes and the fluid passing radially through the said chambers.
2. A device according to claim 1, in which the circular holes are not touching, their respective axes being arranged in a pattern of equilateral triangles.
3. A device according to either claim 1 or claim 2, in which at least two bodies, each in the form of flat plates, are superposed one against the other in such a way that the holes correspond co-axially from one plate to the other.
4. A device according to any one of the preceding claims, in which the external surface of each heat exchange unit comprises a surface of revolution substantially in the shape of a diabolo from which external fins project into the chamber defined by the heat exchange unit and the hole in which it is located, the heat exchange unit also having an axially extending passage therethrough, internal fins projecting into this passage.
5. A device according to any one of claims I to 3, in which each heat exchange unit is formed by a portion of round tube to each axial end of which is welded an external flange.
6. A device according to claim 3, in which each heat exchange unit is defined between two flanges welded on the outside of a cylindrical tube, all the flanges of one series of coaxial units being welded to the same tube, which extends through the entire heat exchange device transversally in relation to the plates.
7. A device according to any one of claims 4 to 6, in which the axial peripheral ends of each heat exchange unit are welded to the body of this unit by a ring of weld which seals off the space available between the exchange unit and its associated chamber from the exterior of the body.
8. A device according to any one of claims 4 to 6, in which two consecutive units are separated by a seal owing to which their internal cavities communicate with each other but are fluid-tight.
9. A device according to any one of Claims 4 to 6, in which two consecutive

units have exactly the same junction plane at two consecutive bodies, the units and the bodies having the same thickness and their respective parallel nat surfaces being machined then applied one against the other with an intermediate layer of joining paste.
10. A device according to any one of the preceding claims, in which each heat exchange unit is formed by a surface of revolution pierced by at least one hole, connecting an internal cavity of the unit to the chamber defined by the unit and the hole in which it is located, so as to bring about mixing of fluids circulating in the cavity and in the chamber respectively.
I I. A device according to Claim 3, or any one of claims 4 to 10 when dependent on claim 3, in which two consecutive plates are welded one against the other by a peripheral ring of weld forming a seal.
12. A device according to claim 3, or any one of claims 4 to 10 when dependent on claim 3, in which all the plates are held together in a single rectangular block by means of bolts which pass through all the plates, each bolt being locked by a nut bearing on one outside plate, whilst its head bears on the other outside plate.
13. A device according to claim 12, in which the block comprises central plates each comprising a metal peripheral portion and a central plastics portion enclosing the exchange units, the central plates being sandwiched between outside plates entirely of metal, and the device being able to operate with circuits of fluid at high pressure.
14. A device according to claim 3 or any one of claims 4 to 13 when dependent on claim 3, in which the drillings provided in the thickness of the plates between the circular holes are arranged so that a first fluid circulates in an internal axial cavity of each unit, whilst a second fluid, which circulates in the thickness of each plate in the said chambers, passes from one unit to the other following an overall zig-zag path ih each plate before reaching the following plate and passing through it in the same way.
15. A device according to claim 14, in which the first fluid which circulates in the internal cavities of the units passes through each row of co-axial units before passing through the next row in the opposite direction, the overall path being in successive planes perpendicular to the planes of the plates, in such a way that the first and the second fluids circulate in opposite directions along their walls of thermal exchange inside each unit. the entry of the first fluid being located near to the outlet of the second fluid, and vice versa.
16. A device according to either of claims I and 2, in which all the circular holes are blind and open on the same face of the body to receive an exchange unit constituted by a plug carrying at least one groove which defines a chamber for the circulation of a fluid from one blind hole to another within the body, and a free rubbing surface.
17. A device according to claim 16, in which each plug has at least one drilling which establishes communication between two different zones of the groove.
18. A device according to either one of claims 16 and 17, in which the plugs have each a hole connecting the groove to the external axial face to provide a restricted leak of fluid, the fluid spreading on this external face to lubricate it.
19. A device according to any one of claims 16 to 18, in which each plug carries several successive grooves to increase the surface offered for thermal exchanges with the fluid circulating around the plugs.
20. A device according to any one of claims 16 to 19, in which each plug has a fixed peg which is engaged in a hole provided in the axial end of the associated chamber, in order to prevent the plug from revolving.
21. A device according to any one of claims 16 to 20, in which the external surface of the plug carries a friction lining of a material different from that of the plug.
22. A device according to any one of claims 16 to 21, in which each plug has an O ring located in a groove provided near to the base of the plug to prevent any penetration of fluid between the bottom of the associated chamber and the base of the plug.
23. A device according to claim 22, in which an elastic support is interposed between the base of the plug and the bottom of the associated chamber, whilst the plug is fitted so as to slide axially within its blind hole.
24. A device according to Claim 22, in which the plug is fitted to slide axially in its blind hole, and does not extend to the full depth of the blind hole, so that, according to the pressure of the fluid, each plug may either be retracted into its blind hole or may project from its body.
25. A device according to any one of claims 16 to 24, in which the upper groove of each plug has on the side nearest to the external face of this plug a generating line only slightly inclined in relation to the axis of the plug in order to increase the rigidity of the peripheral portion of said external surface.
26. A device according to claim 16, in which each plug is constituted by at least two parallel plates or discs connected to each other by an intermediate diametrically transverse wall, each wall face being opposite two openings drilled in the body parallel to the said two faces of the body, but leading respectively to the blind holes of the two consecutive plugs of the adjacent row.
27. A device according to any one of claims 16 and 26, in which each plug is permanently fixed and adjusted in its blind hole, whilst its free surface is machined in line with that of the body.
28. A device according to any one of claims 16 to 26, in which the space left free between the line of the external faces of the prqjecting plugs and the external face of the body is filled by a solid lubricating material constituted for example by agglomerated graphite.
29. A process for the manufacture of a device according to claim 16, in which all the plugs are first locked against a fixed support in the body and then machined all together on their external surfaces, which project in relation to that face of the body on which the blind holes open.
30. A process according to claim 29, to manufacture a device in which the plugs are able to slide axially, each plug being temporarily held during machining by means of a rigid annular support placed between the bottom of the plug and the bottom of the associated blind hole, the plug being hence supported pressed against the support in the working position which it will occupy in service, if necessary a screw being engaged through the body and screwing it into a hole tapped in the lower face of the plug, whilst once the machining is finished, the screw is removed, its seating hole being blocked by a separate plug and the support removed.
31. A process to manufacture a device according to claim 6, in which the device is assembled plate by plate, all the tubes being first placed in the first plate, and all the washers being welded to each plate before the following plate is introduced on to the tubes.
32. A heat exchange device constructed and arranged substantially as hereinbefore described, with reference to Figures 1 to 10, or any one of Figures 11 to 19 or 21 to 66 of the accompanying drawings.
33. A process for the manufacture of a heat exchange device substantially as hereinbefore described, with reference to Figures 1 to 10, or any one of Figures Il to 19 or 21 to 66 of the accompanying drawings.