US 3820598 A
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Description (OCR text may contain errors)
United States Patent [191 Fenger et al.
[ June 28, 1974 APPARATUS FOR COOLING LIQUIDS Inventors: Horst Fenger, Hose]; Ferdinand Pfeifer, Krefeld, both of Germany Assignee: Messer Griesheim GmbH,
Frankfurt, Germany Filed: Nov. 27, 1972 App]. No.: 309,807
 Foreign Application Priority Data Nov. 26, 1971 Germany 2158716 US. Cl. 165/160, 62/394 Int. Cl. F28d 7/00 Field of Search ..62/98, 218-221 394,
References Cited UNITED STATES PATENTS 2/1949 Mojonnier 62/394 4/1963 Barger 62/389 Primary ExaminerMeyer Perlin Attorney, Agent, or FirmConnolly and Hutz 5 7] ABSTRACT Apparatus for cooling liquids, particularly fuels, comprises steps of passing liquid to be cooled along plurality of separate paths interconnected at starting and end points of paths. Cooling medium is countercurrently passed along a plurality of paths equal to number of liquid paths with each path of cooling medium associated with one of liquid paths. Cooling medium paths are interconnected at starting and end points.
Devicefor cooling liquids comprises heat exchanger having housing and plurality of pipe assemblies therein..Each pipe assembly includes inner pipe for carrying liquid being processed and outer pipe for carrying cooling medium. Chambers in housing interconnect all of inner pipes and separately interconnect all of outer pipes.
3 Claims, 3 Drawing Figures PATENTEDJUH28I974 3.820.598
- sum 1 0f 2' Fig. 1
mzmaumzamm 3820 598 I mg or 2 APPARATUS FOR COOLING LIQUIDS BACKGROUND OF THE INVENTION The present invention relates to an apparatus for i cooling liquids, particularly fuels or similar liquids, to nearly the freezing point or pour point. It is particularly useful in the aircraft industry for testing fuel equipment with fuels when they are near freezing point. The fuel equipment in question includes equipment used for The cooling test in the entire examination of the stated apparatus only takes a short period of time, and the test benches with individual cooling machines and a cooling medium in an individual cycle are very expensive. Additionally, since the cooling medium is only cooled to the temperature of the fuel to be cooled, the heat exchange between the cooling medium and the fuel must be very large in order to achieve in the required fuel throughput the desired cooling up to nearly the pour point. The customary equipment is expensive to manufacture and also has an increased floor space requirement.
SUMMARY OF THE INVENTION The object of the present invention is to eliminate the stated disadvantages and to provide a process and an arrangement for the cooling of liquids, particularly fuels or similar liquids, up to nearly the-freezing point or pour point, particularly for examining fuel equipment, such as devices for conducting the fuel, dosing the fuel, and the like, which has low manufacturing costs and quick cooling of the fuel even with large throughput quantities.
According to the present invention, it is proposed that the cooling of the liquid occur directly by the vaporization of a cooling medium supplied to a pipe heat exchanger. The vaporization temperature of the cooling medium is below the freezing point or pour point of the liquid to be cooled, and the supply of the coolant and the flow-through speed of the liquid to be cooled are selected in such a manner that the liquid emerges from the heat exchanger at a temperature near its freezing point.
Preferably, the coolant is liquid nitrogen, and the liquid is conducted with a spin through the pipes of the heat exchanger in order to avoid a sticking or freezing of the liquid on the walls of the pipes through which it is conveyed.
The device for the use of the process consists of a pipe heat exchanger having a pipe assembly characterized in that each assembly has a double wall and the liquid flows through the inner opening of the assembly while the vaporizing coolant is introduced from the bottom upwardly in the space between the inner and outer pipes of the assembly.
As a further development of the arrangement, it is proposed that each double-walled assembly consist of two telescoping concentric pipes. Each inner pipe is tightly connected at each end between a pair of intermediate plates in the housing of the heat exchanger while each outer pipe is tightly connected to another intermediate plate. An inlet feed pipe for the liquid coolant is arranged between the lowermost and adjacent intermediate plates. An outlet feed pipe for the vaporized coolant is arranged in the housing of the heat exchanger between the uppermost and adjacent intermediate plate.
Advantageously. the housing of the heat exchanger is provided with a bellows for equalizing the variable thermal expansions between the inner pipes and the housing.
In order to increase the passage of heat in the heat exchanger, it is proposed to spirally wind a web about the inner pipe with a certain pitch. The web engages the interior of the outer pipe.
In order to achieve the spin of the liquid in the passage through the heat exchanger pipes, there is arranged in the inner pipe a spirally turned flat band the exterior of which engages the inside surface of the inner pipe.
BRIEF DESCRIPTION OF THE DRAWING Novel features and advantages of the present invention in addition to those mentioned above will become apparent to those skilled in the art from a reading of the following detailed description in conjunction with the accompanying drawings wherein similar reference characters refer to similar parts and in which:
FIG. 1 shows a front elevational view of a heat exchanger according to the present invention with portions broken away to show details;
FIG. 2 illustrates an arrangement for the application of the process of the present invention using liquid nitrogen as a coolant; and
FIG. 3 illustrates an arrangement for the application of the process of the present invention wherein the heat exchanger serves as the vaporizer in a customary cooling system.
DETAILED DESCRIPTION OF THE INVENTION The drawing shows that the heat exchanger for the execution of the present process consists of a housing 1 sealed at each end with housing closures 4. Each closure includes an inlet or outlet connecting pipe 3 with a flange at the outer end thereof. The housing closures 4 are mounted by means of screws 6 and nuts 5 to the housing flanges 7 with seals 8 therebetween. Housing 1 includes a bellows 2 which allows for the equalization of variable thermal expansions. Intermediate plates'l2, l3 and 14 are welded into housing 1, and a plurality of inner pipes 11 for the passage of the fuel are securely welded to the intermediate plates 12 and 13, as shown. A plurality of outer pipes 9 serves to conduct coolant and each pipe 9 is securely welded to the intermediate plate 14 at the lower end of the pipe. The upper end of each pipe 9 terminates just before the intermediate plate 12. In order to conduct the coolant along the longest route possible through the space 9a between each outer pipe 9 and each inner pipe 1 l, a web 10 is spirally wound about the inner pipe. The web ID has a certain pitch and the exterior thereof engages to interior of the pipe 9. As noted above, a plurality of inner and outer pipe arrangements 9, 11 are provided with each such arrangement disposed in the housing 1 in the manner of the one shown in FIG. 1.
A connecting pipe 16 for the liquid coolant is welded to housing 1 in such a manner that the liquid coolant enters the space between the intermediate plates 13 and 14. From there the coolant enters into the spaces 9a between the inner pipes 11 and the outer pipes 9, as is clear from FIG. 1 of the drawing.
The vaporized coolant is drawn off through outlet connecting pipes 18 situated at the housing 1 after it emerges from the upper end of the pipes 9. In order to remove the still liquid coolant from the heat exchanger after shutting off the coolant supply at pipe 16, a connecting pipe 19 is welded to the housing for introducing compressed air into the system. The air may be heated.
In order to prevent adhesion or freezing of the liquid to be cooled to the walls of the inner pipes 11, the passing liquid is given a certain spin in that a spirally turned, flat band 17 is arranged in the inner pipes 11. The width of the flat band corresponds to the inside diameter of the inner pipe 11.
In order to cool the liquid entering from above to nearly the pour point or the freezing point, liquid coolant is introduced through the inlet pipe 16. The coolant flows upwardly in countercurrent fashion through spaces 90 between the inner pipes 11 and the outer pipes 9 and is thereby vaporized. In this manner, for the cooling of the passing liquid, both the vaporization heat of the coolant and the heating of the vaporized coolant are utilized.
In order to achieve the most advantageous cooling effect possible, according to the invention, a coolant is employed whose vaporization temperature is below the pour point or of the freezing point of the liquid to be cooled. Preferably, liquefied gases, particularly liquid nitrogen, are used as the coolants. These materials are usually ordered by a contractor in liquid form and are conducted from a heat-isolating vessel 20 by means of valve 21 to the pipe 16, as shown in FIG. 2. The liquid nitrogen is forced into the heat exchanger by the gas pressure in the container, which is produced by a separate vaporizer (not shown). The quantity of the coolant supplied is regulated depending on the outlet temperature of the fuel from the heat exchanger.
In the described use of liquid nitrogen as coolant, the vaporized nitrogen is released into the atmosphere through pipe 18.
In the arrangement illustrated in FIG. 3, the heat exchanger functions as a vaporizer in the circulation of a customary cooling system. However, a stipulation with an arrangement of this type is that the coolant used have a vaporization temperature which is not excessively below the pour point or the freezing point of the liquid to be cooled. The customary coolants which may be used in such cooling systems have a vaporization temperature of 75 C., which is sufficient to achieve a satisfactory cooling effect. However, in this case the heat exchanger must be made larger than that used with liquid nitrogen as the cooling agnetv In the arrangement illustrated in FIG. 3, the coolant is compressed in compressor 24, liquefied in condenser 22 and enters the heat exchanger in a liquid state through throttle 23 by means of inlet pipe 16. It is vaporized there with the cooling of the passing liquid and is discharged as vapor through pipe 18 and recycled back to the compressor 24 by means of conduit 25. In using the novel process, here too the cooling of the liquid in the heat exchanger is achieved directly by the vaporization of the coolant in the heat exchanger so that the arrangement is very much simplified and is less expensive to manufacture as compared to the art mentioned in the introduction.
The device disclosed, as already mentioned, is particularly suited for use in test bench equipment for the examination of fuel apparatus, such as devices for conducting fuel, dosing the fuel, and the like, in the proximity of the pour point of the fuel. However. the use is not limited to this example since the process and the device may advantageously be used everywhere where quick cooling of a liquid is required without encountering the danger of having the conduits obstructed by the sticking or freezing of the liquid at the walls. This is the case, for example, with liquids which are cooled to prevent or delay a chemical reaction.
What is claimed is:
1. A device for cooling liquids comprising a heat exchanger having a housing and a plurality of pipe assemblies therein, each pipe assembly including an inner pipe constructed and arranged to carry the liquid being processed and an outer pipe constructed and arranged to carry a cooling medium, chamber means in the housing interconnecting all of the inner pipes and separately interconnecting all of the outer pipes, the housing including opposite end plates for closing the housing and three intermediate plates spaced apart in the housing, each of the inner pipes extending between the uppermost and lowermost intermediate plates and communicating with the spaces in the housing above the uppermost plate and below the lowermost plate, and each of the outer pipes being connected to the middle intermediate plate and providing communication between the space in the housing on opposite sides of the middle intermediate plate, and a bellows between the uppermost and middle intermediate plates for the equalization of the variable thermal expansions between the inner pipes and the housing.
2. A device as in claim 1 including a spiral web on the outside of each inner pipe with the exterior of the web engaging the interior of the outer pipe.
3. A device as in claim 2 including a spirally turned flat band inside each inner pipe engaging the inside surface of the inner pipe.