Exchanger For Cooling Fluids

Abstract

This invention relates to a cooling exchanger for cooling fluids in which there are two pipe systems through which are passed respectively the fluid to be cooled and the cold-producing fluid. The pipes for the cold-producing fluid are distributed among the pipes for carrying the fluid to be cooled and both sets of pipes are submerged in a refrigerating liquid.

Description

FIELD OF THE INVENTION

The present invention relates to an exchanger for cooling fluids, particularly gas and air, of the type in which cold is transferred between the cold-producing fluid and the fluid to be cooled through the agency of a "refrigerating fluid," as it is called, for example a liquid which may be capable of freezing hard.

BACKGROUND OF THE INVENTION

In cooling exchangers of this type, the refrigerating fluid is contained in an enclosure in which are immersed two pipe systems, one of which carrys the cold-producing fluid and is connected to a refrigerating sleeve, wherein the fluid to be cooled passes through the other pipe system. Exchangers of this kind, in contrast to those in which a fluid is cooled by direct contact with a bank of tubes in which the cold-producing fluid is evaporated, offer the advantage of providing an accumulation of cold built up in the intermediate refrigerating fluid so enabling the frequency of start-up of the refrigerating machine to be reduced. However, the output is nevertheless not very satisfactory. In effect, the transfer of cold at the exchange surface between the refrigerating fluid and the gas to be cooled occurs under poor conditions, since the mass of the gas is small. To improve the rate of transfer of cold, recourse has been made to reducing the gap between the temperature of the gas to be cooled and that of the refrigerating fluid, but there is a minimum gap that cannot be decreased, since it would then be necessary to increase excessively the throughput of refrigerating fluid.

SUMMARY OF THE INVENTION

The cooling exchanger in accordance with the invention enables this drawback to be decreased. The pipes for the cold-producing fluid are arranged in the pipe system for handling the fluid to be cooled and the whole of both banks are submerged in the refrigerating liquid.

In a preferred embodiment, the pipes through which passes the fluid to be cooled are regularly spaced over the cross-section of the enclosure. The pipes of the cold-producing pipe system are arranged in several planar and horizontal banks, which are horizontal or inclined to the longitudinal plane of symmetry of the enclosure and are interposed between the pipes of the first system.

In accordance with a further feature of the invention, transverse partitions, through which pass the pipes of the two systems and which form a baffle passage, are fitted in the enclosure containing the refrigerating fluid. An exterior pump causes the refrigerating fluid to circulate at a great rate through this passage, so that it moves successively into contact with the cold pipes and the pipes that are to be cooled.

Because of this arrangement, the refrigerating fluid is forced to flow perpendicularly to the pipes of the two systems so that the turbulence so caused provides a good transfer co-efficient. Furthermore, since the pipes through which the cold-producing fluid pass are interposed between the pipes through which the fluid to be cooled pass, the refrigerating fluid moves successively and alternately into contact with the cold pipes and the pipes to be cooled. As a result, the refrigerating fluid is cooled a great number of times so that its temperature is practically constant and very close to that of the cold-producing fluid. The equipment thus possesses the advantages of refrigerators in which the fluid to be cooled moves in direct contact with the pipes for directly expanding the cold-producing fluid, and it also possesses the advantages of apparatus employing an intermediate refrigerating fluid.

BRIEF DESCRIPTION OF DRAWINGS

For a better understanding of the invention reference will now be made to the accompanying drawings which illustrate one embodiment of an apparatus according to the invention.

FIG. 1 is a longitudinal section;

FIG. 2 is a cross-section on the line II--II of FIG. 1; and

FIG. 3 is a further cross-section on the line III--III of FIG. 1.

DESCRIPTION OF SPECIFIC EMBODIMENT

As shown in the drawing, the refrigerating exchanger of the invention is constituted by a cylindrical container 1 closed at its two ends by caps 2 and 3, which are connected to the container 1 by means of flanges and bolts (not illustrated). Between that end of the container 1 closed by the cap 3 and this cap there is fitted a plate 4, a similar plate 5 being fitted in the container 1 at some distance away from its other end so as to form a chamber 6.

Pipes 7, 7' etc. (FIGS. 1 and 2) extend between the two plates 4 and 5 and pass through them. They form a first pipe system through which passes the fluid to be cooled. Fluid enters the system through a port 8 in end cap 3. The end cap is divided into two chambers 9 and 9' by a median partition 10, and fluid is discharged through the port 8'. The pipes 7 of the bank thus form two groups, an upper group of pipes through which the fluid to be cooled passes from right to left, and a lower group of pipes through which this fluid passes from left to right.

The pipes 7, 7' etc. in which the fluid to be cooled circulates are distributed substantially uniformly over the cross-section of the enclosure defined by the container 1. In this pipe system are inserted or interposed the pipes through which passes the refrigerating fluid supplied by the refrigerating machine 11. These pipes are staggered over the transverse plate 5 and are divided into three planar banks 12, 12' and 12" (FIGS. 1 and 2), each of which is constituted by three pipes which are interconnected by return bends as can be seen in FIG. 1. The three lower pipes are connected, as shown in FIG. 1, to the distributor 13 connected to the refrigerating machine, in which distributor the fluid expands, whereas the three upper pipes are connected to a collector 14 which passes the vaporized fluid to the machine 11. The cold pipework 12 must be horizontal or must slope downwards so as not to form pockets in which lubricating oil could be trapped. The distributor 13 and the collector 14 are connected to the refrigerating machine 11 by pipes 15 and 16 which pass through the wall of the container 1 to the interior of the chamber 6, fluid-tight seals being provided between these pipes and said wall. Thus, these fluid-tight conduits do not require to be dismantled when it is required to clean the banks of pipes or to replace certain of the pipes. For this purpose, it suffices to remove the end caps 2 and 3, which operation can be carried out without difficulty.

Transverse partitions 17-18, 17'-18', 17"-18" etc. are fitted inside the container 1 so as to form a baffle path for the refrigerating fluid. A pump 19, connected to the container 1 at 20 and 21 near the plates 4 and 5, causes the refrigerating fluid to circulate through the enclosure and in contact with the pipes. The pipes 7 and 12 pass through the partitions 17 and 18 which help to support these pipes.

It will be seen that, due to the partitions 17 and 18, the interior of the container 1 is divided into a certain number of successive chambers through which the refrigerating liquid, pressurized by the pump 19, passes alternately in the upward and downward directions. Consequently, this liquid, during its entire travel through the container 1, moves alternately into contact with the cold pipes 12 and with the pipes 7 to be cooled, and this enables the above-mentioned advantages to be achieved.

The volume of refrigerating liquid supplied by the pump is kept at such a level that it does not entirely fill the container 1. This level can be checked through an inspection window 22. This gives, on the one hand, turbulent flow between the pipes of the two systems and, on the other hand, a good coefficient of cold transfer. However, if it is required to create an accumulation of cold by freezing the refrigerating liquid, this incomplete filling of the container 1 ensures the necessary margin of safety to cover expansion caused by the freezing.

When it is required to use a non-freezing liquid, alcohol, glycol or aqueous solutions of these substances will be employed so as to lower the freezing point. Mercury may also be used.

Where it is required to use a liquid that can freeze, pure water, a low-concentration brine or an eutectic solution may be employed.

Claims

I claim:

1. In an exchanger for cooling fluids of the type in which heat is transferred from the fluid to be cooled to an intermediate refrigerating fluid and then to a cooling fluid, said exchanger including an enclosure, first and second pipe systems arranged within said enclosure, each pipe system comprising a multiplicity of pipes, means for passing a cooling fluid through said first system, said first system having connector means for coupling to a refrigerating machine, means for passing a fluid to be cooled through said second system, and an intermediate refrigerating liquid within the enclosure, the improvement wherein said pipes of both said first and second systems are distributed within said enclosure and submerged in said refrigerating liquid, said pipes of said first and second pipe systems being interspersed respectively with each other throughout such liquid.

2. A cooling exchanger according to claim 1, wherein said pipes of said second system are regularly spaced over the cross-section of the enclosure and said pipes of said first system are arranged horizontally or at an incline relative to a horizontal longitudinal plane of symmetry of the enclosure.

3. A cooling exchanger according to claim 1, comprising transverse partitions spaced apart in said enclosure and forming a baffle passage, apertures in said partitions through which pass the pipes of said first and second pipe systems, and pump means for circulating said refrigerating liquid through said baffle passage.

4. A cooling exchanger according to claim 1, in which said enclosure includes a substantially cylindrical container, first and second transverse plates adjacent respective ends of the container, apertures in said first and second plates for receiving ends of pipes of said second pipe system, apertures in said second plate for receiving ends of pipes of said first pipe system, first and second cap members closing the ends of the cylindrical container, first and second chambers defined between said cap members and said first and second transverse plates, a longitudinal partition in said first chamber defining first and second compartments, inlet and outlet ports in said first and second compartments respectively for said fluid to be cooled, means for feeding said cooling fluid to the ends of said pipes of said first system at said second chamber, a collector in said second chamber for receiving vaporized cooling fluid from ends of pipes of said first system, and a refrigerating machine connected to said connector means of said first pipe system through said feeding means and said collector.

5. A cooling exchanger according to claim 4, wherein pump means for circulating said refrigerating liquid is connected to said enclosure adjacent the inlet and outlet for the fluid to be cooled.

6. A cooling exchanger according to claim 5, wherein the volume of the refrigerating liquid in circulation is selected so as not to completely fill the enclosure.