US 2613065 A
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M. DIDIER COOLING RADIATOR Oct. 7, 1952 2 SHEETS SHEET 1 Filed March 17, 1948 U U U U U U nU U U vA H U U U U n&
E06]; 50 wdzzzefiam' Oct. 7, 1952 M. DIDIER 2,513,065,
COOLING RADIATOR Filed March 17, 1948 2 SHEETS-SHEET 2 Inventor Maur'lce flldier',
Patented Oct. 7, 1952 COOLING RADIATOR Maurice Didier, Asnieres, France, assignor to Societe Anonyme des Usines Chausson, Asnieres,
France, a joint-stock company of France Application March 17, 1948, Serial No. 15,456 In France November 21, 1947 The cooling radiators composed of groups of tubes, which are used on motor vehicles and aircraft comprise rows of equidistant tubes which are arranged behind one another and through which the liquid to be cooled circulates, the
1 Claim. (Cl. 257-124) cooling liquid flowing successively through said rows.
Since the pitch of the tubes of said rows is the same, the tubes located at the front of the radiator are licked by cold air, whereas the tubes located more to the rear are licked by hot air. The minimum heating of the air is 30 C- in a motor car and 45 C. in an aircraft. Consequently, if it is assumed that the ambient temperature is +30 C. and that the average temperature of the fluid to be cooled is to remain about 90 C., the first row of tubes operates with a difference of 9030=60 0., whereas the last row operates with a difference of 90-60=30 C. Now, the amount of heat carried away is proportional to the temperature difference, so that the fins welded to the first row of tubes carry away twice as much heat as those welded to the last row, although they are of the same thickness and, the pitch of the tubes being the same, the distance travelled by the heat is identical. Consequently, the radiator has too much metal at the rear and not enough at the front.
The object of the present invention is to vary, together or separately, one or more characteristic parameters inside the radiator, according to a progression which takes into account the condition of the fluids at each point of the depth of the nest. In the above example, it was found that the amount of heat carried away is greater at the front of the radiator than at the rear and the following principle was deduced therefrom: the metal should be used more efficiently at the front than at the rear, its distribution should be calculated according to the differences of temperature.
Another object is to provide a cooling radiator which comprises a group composed of successive rows of tubes through which the liquid to be cooled is to flow, the cooling fluid being adapted to flow between said rows, in which the tubes are spaced apart from one another a distance which, according to the invention, increases in the successive rows from the front to the rear, said tubes being passed through fins, the thickness, the depth and the spacing of which are uniform.
A furtherobject is to mount, on the equidistant tubes of a conventional group, fins of decreasing exchange efficiency, number, area or thickness from the front towards the rear.
A still further object is to obtain a variation element and to arrange it according to the invention by using materials of different heat conductivity for forming the indirect surfaces, for example copper, aluminium and steel fins, the conductivity of which has been classified herein in decreasing order and may form a parameter similar to the variation of the thickness of the fin hereinbefore considered.
Each of these parameters make it possible, alone or in combination with the others, to ob tain according to the invention a distribution which takes into account the difference between the temperatures of the cooling fluid and the fluid to be cooled. i The invention is however notlimited to the variation only of the parameters described herein, but includes any relative arrangement of the direct and indirect heat exchange surfaces which may be obtained according to these principles.
Furthermore, in the example of the motor car or aircraft radiator given at the outset, it is observed that the resistance offered by the conventional nest to the flow of the air increases from the front towards the rear as the air is heated, owing to the fact that it increases in volume by expansion and its kinematic viscosity increases, and the following second principle may be deduced therefrom: when the fluid in question is a gas, the passage cross-section which is offered to it in the radiator should vary according to its heating.
By way of example of a radiator applying these two principles, it is possible to arrange successive rows of tubes for the flow of the liquid ot be cooled and between which the cooling air flows, the tubes being spaced apart from one another a distance which increases in the successive rows from the front to the rear of the :radiator.
According to another feature, fins or indirect surfaces are mounted on the tubes and, preferably, said fins are closer together and/or of smaller area on the successive rows of tubes from the front towards the rear of the radiator.
A radiator constructed according to the invention provides a substantially equal heatex- Further objects and advantages of my invention will be apparent from the description and claim.
In the drawing, in which an embodiment of my invention is illustrated:
Fig. 1 is a diagrammatic cross-sectionalview taken transversely of a group of heat exchange tubes.
Fig. 2 is a side view in elevation of the tubes ofv another group.
Fig. 3 is a similar side view in elevationto Fig. 2 illustrating a modification.
Fig. 4 is a cross-sectional view taken transversely through a group of tubes of another embodiment.
Fig. 5 is a side view in elevation showing another modification.
Fig. 6 is a diagrammatic cross-sectional view corresponding to Fig. 5.
Fig. '7 is a side view in elevation of a further modification.
Fig. 8is a cross-sectional view corresponding toFig. 7.
According to Fig. l, the group comprises a first row of tubes I spaced a short distance apart from one another. Behind these tubesis placed a second row of tubes 2 which are spaced further apart from one another than the tubes l. A third row of tubes 3 is located behind the row 2 and the tubes of said third row are spaced further apart from one another than those of the second row.
In Fig. 2, successive rows of tubes 1, 5, 6 have been shown. In the front row 4, numerous fins or. other secondary surfaces 1 are arranged very close together on these tubes. On the other hand, in the rows '5 and 6, the fins .B are spaced further apart and have a smaller total area.
Fig. 3 shows another .construction in which the tubes 8, 10, H are alternately provided with fins l2 extending over these three tubes, fins l3 only extending over thetubes .9 and i and fins l4 only extend round the front. tube 9.
Fig. 4 shows another embodiment in which the group comprises three rows of tubes 15, 1.6, 111.
In the first row [5, the tubes arevery close to one another, in the second row I6, the tubes are spaced further apart and in the third row I! the tubes are spaced still further apart from one another. Fins l8, which are as large .as possible, surround the tubes l and are located very close together so as to form secondary heat exchange surfaces of very large area. Other fins l9 surround the tubes 16.; these fins may be further apart and/or be of smaller area than the fins [8.
The third row of tubes 17 is also provided with fins .20 which are .further apart and/or of smaller area than the fins 19. In all these embodiments, the cold air licks the first row of tubes, as .indicated by the air flow directional arrows A, Figures .1, 4, 6 and 8.. The first row of tubes offers very large primary heat exchange and secondary heat exchange surfaces since not only are the tubes very close together, but the fins are also very close together and of as largean area as possible. The air is heated against this system, it expands and its viscosity increases. When it reaches the second row of tubes, it only encounters primary heat exchangev and secondary heat exchange surfaces of smaller area, and there is 'a larger space between these surfaces which enables it to pass with its expanded volume without increasing its speed. The same effect is produced when the air reaches. the third row '4 of tubes. There also, it encounters smaller primary and secondary heat exchange surfaces than in the previous row, and there are larger spaces for it to pass through which enable it to fiow through this third row without increasing its speed despite the increase in its volume and viscosity.
According to Figs. 5 and 6, the rows of tubes 22, 23, 24 are successively spaced further apart from the front to the rear of the nest and the fins 25, 26, 2"! surrounding said tubes are progressively spaced further apart and also of smaller area and decreasing thickness from the front to the rear of the radiator.
In the modification of Figs. 7 and 8, the nest comprises rows of tubes 28, 29, 30 which are successively spaced further apart from the front to the rear of said nest and fins 3|, 32, 33 surrounding said tubes which are decreasing both in area and thickness from the front to the rear of the radiator.
In all the foregoing embodiments, the device considered is .a cooler for a fiuid, which may be liquid or even gaseous, the cooling being obtained by the flow of a gas which in so doing is itself heated and therefore increases in volume. and viscosity but the invention is also applicable to the case of the heating of a .fiuid by an external gas which in so doing .is cooled and thus decreases in volume .and viscosity. In this latter case, the distance between the fins would of course decrease in the depthwise direction from the front towards the rear, contrary to the previous embodiments, soas to favor the flow of the external v,gas, but the tubes would remain closer together at the front than at the rear, or, .if the distance between the tubes was constant, the thickness of the fins would be greater at the front than at the rear, since according to the invention, these variations are proportional to the differences of temperature.
The construction of a device according to. the invention may be effected inside a single group, all the tubes being, secured together by the whole or a portion of the fins as here'inbefore described, but it may also be embodied in .a composite radiator, the operative element of which comprises a plurality of groups which differ from one another by the pitch and/or the thickness of the fins, the pitch of the tubes, etc., involving the features of the invention together or separately. r
The invention is obviously not limited to the embodiments illustrated and described. The radiator may comprise any number of successive rows of tubes and the increase of pitch .between the tubes of the rows may be calculated in any manner according to the desired application. The pitch may be increased for each .row or only every other row. Similarly, the secondary heat exchange surfaces may be the same on each tube or may be decreased in the rows of tubes from the front towards the rear.
Further modifications will be apparent to those skilled in the art and it is desired, therefore, that the invention be limited only by the prior art and the scope of the appended claim.
Cooling radiator comprising a group .of these successive rows of tubes which are successively spaced further apart in each row so that the tubes decrease in number and area from the front row to the rear row of said group and .a plurality of transverse fins spaced longitudinally along the lengthof the rows of. tubes and arranged in groups of three, the first fins of each group extending crosswise of and around the ,front row of tubes, the intermediate fin of each v against the front surfaces of the 'frontrow of tubes.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,524,520 Junkers Jan. 27, 1925 1,781,781 Higgins Nov. 1.8, 1930 1,899,098 Mack 1 Feb. 28, 1933 1,911,522 McIntyre May 30, 1933 2,006,649 Modine July 2, 1935 2,055,549 Modine 1-. Sept. 29, 1936 FOREIGN PATENTS Number Country Date 380,801 France Oct. 19,1907
OTHER REFERENCES Handbook of Chemistry and Physics, published by Chemical Rubber Publishing Co., Cleveland, Ohio, 20th edition, pages 1299 to1303.