US2864589A - Heat transfer device - Google Patents

Description

Dec. 16, 1958 H. T. BOOTH ET AL HEAT TRANSFER DEVICE Filed June 14, 1955 HEAT TRANSFER DEVICE Harry T. Booth, Frank E. Carroll, Jr., and Kenneth O. Parker, Dayton, Ohio, assignors to United Aircraft Products, Inc., Dayton, Ohio, a corporation of Ohio Application `lune 14, 1955, Serial No. 515,314

' 2 claims. (c1. 251-4) This invention relates to heat exchange apparatus, and particularly to a generally new combination of valve and heat exchanger of especial untility in aircraft.

An object of the invention is to provide a valve and heat exchanger combination as described especially characterized by smallness of size and lightness of Weight in relation to its heat transfer capabilities.

Another object of the invention is to introduce a generally new structural principle in devices of the kind described, it being contemplated to fabricate the device largely out of sheet metal, with the several parts thereof being united into an integrated form after assembly, as bybrazing.

A further object of the invention is to present a unitary valve and heat exchanger combination adapted for simplilied access and removal of the valve element.

Still another object of the invention is to present a valve assembly, in heat exchange apparatus as described, operable accurately to regulate the temperature of at least one of the fluids circulated in a valve and heat exchanger combination.

A still further object of the invention is to provide contoured valve means in a valve assembly as described so constructed and arranged that the rate of uid ow thereby is not proportional to the rate of movement of the valve means.

A still further object of the invention is to present a heat exchange device which on account of its size and weight is particularly adapted as an engine accessory in aircraft, for example, as a fuel heater.

In the drawings,

Fig. 1 is a view in longitudinal section of heat exchange apparatus in accordance with the illustrative embodiment of the invention; j

Fig. 2 is an enlarged view in fragmentary form, of a valve element and valve seat comprised in the heat exchange apparatus, showing the relationship of the contoured valve face to the valve seat; and

Fig. 3 is a view in cross section taken substantially along the line 3-3 of Fig. l.

In its illustrative embodiment, the invention has particular reference to the lubricant circulating and fuel supply systems of aircraft and other vehicles which operate at times under atmospheric conditions of very low temperature, as on the order of 65 F. below zero. At extremely low temperatures of this value contained water in the fuel is in a condition conducive to icing at the fcarbueretor or fuel injectors. It is desirable to warm the fuel-water solution and its has been proposed to do this by interposing in the fuel supply line a heat exchanger comprising essentially a core of thin wall tubes with the fuel flowing through the tubes and circulating engine oil flowing over and around the tubes. The engine oil is of course heated in the operation of the engine and in flowing through the described core rejects heat to the fuel. A heat exchange core of a kind useful in such an application is disclosed in our copending application S. N. 496,815, tiled March 25, 1955, for Heat Transfer States Patent() ICC Method and Apparatus. The instant invention has in view an integrated valve and heat exchanger combination of which a heat exchange core as disclosed in the application above identified is but one element.

Thus, the heat exchange section of the present combination may be constructed for heating of a fuel ow on the order of 260() pounds per hour from minus F. to F., the total amount of heat transferred at this condition being on the order of 2680 B. t. u. per minute at 70 F. A valve as presently incorporated in the system, serves to regulate or to stabilize the fuel temperature at or near a selected value by adjustment, in response to a Ichanging condition of the fuel, the position of a valve element controlling the rate of flow of the oil. It is a feature of the invention to avoid wide fluctuations in fuel temperature as a result of the described regulation of oil iiow through use of a contoured valve face by which the size of the opening controlled by the valve does not change in direct proportion to the extent of movements of the valve.

Referring to the drawings, according to a further feature of the invention the heat transfer apparatus hereof is constructed in the main of sheet metal with the parts being brazed to define an integrated structure. Thus, the apparatus includes a sheet metal cylindrical heat exchanger casing 10 and in parallel adjacent relation thereto a cylindrical sheet metal valve casing 11. One end of the casing 10 is closed by a sheet metal curved insert 12. A radial opening 13 is formed in the casing 10 near the end closure 12 and receives one end of a tubular connector 14, the other end of which extends into intertting relation with a turned out flange 15 on the casing 11 which defines a radial opening 16 therein. Longitudinally spaced from the radial opening 13 in the casing 10 is another radial opening 17. A partial jacket 18 is mounted on the casing 10 in covering relation to the opening 17 and is formed with a raised portion 19 in underlying contacting relation to the casing 11 and having an opening 21 aligned with an opening 22 in the casing 11. Also formed in `the casing 10 is another radial opening 23 receiving a hollow tting 24, the opening 23 being on the opposite side of the opening 17 and substantially in line therewith.

`At that end of the casing 10 opposite end closure 12 a sleeve 25 is installed, in which in turn is mounted a fitting 26 having a central opening 27. Within the casing -10 are longitudinally spaced apart header plates or tube sheets 28 and 29 which are in embracing relation to the radial openings 17 and 23 and which dene with the oppositely disposed end closures an inlet chamber 31 communicating with opening 27 and an outlet chamber 32 communicating with radial opening 13. The plates or sheets 28 and 29 have through longitudinal openings therein in which are mounted the opposite ends of heat exchange tubes 33. A iluid admitted to chamber 31 by way of opening 27 may thus flow longitudinally through the tubes 33 to the outlet chamber 32 and be discharged from the heat exchanger casing by way of opening 13. Another fluid, admitted to the heat exchanger casing by way of opening 17, may pass around the tubes 33 in heat transfer relation to the first mentioned lluid and escape from the apparatus by way of opening 23. The heat exchange core may comprise, in addition to the plates 28 and 29, and the tubes 33, longitudinally extending baille plates 34 each having an opening 35 at one end 'thereof and reversely arranged for a circuitous ow of the second lmentioned uid over the tubes 33 in the manner indicated 36 over a part of their length for a variable film coeflicient of heat transfer between the uids flowing through and around the tubes and for a less restricted ow of oil in the beaded tube area.

The valve casing 18 has, in addition to the radial openings 16 and 22, a radial opening 37 in opposed substantially aligned relation to the opening 16 and defined by a turned out flange 38 received in a fitting 39. On the opposite open ends of the valve casing 11 are ring-like fittings 41 and 42. Installed within the valve casing 11 are partition means in the form of ring shaped members 43 and 44 on respectively opposite sides of the opening 22. The effect of the partitioning ring shaped members 43 and 44 is to define in the valve casing 11 a longitudinal series of chambers 45, 46 and 47.

The structure as thus far described constitutes an integrated assembly. The casings and 11, connector devices 14 and 18, and end closure 25 are assembled in the organization shown and, held in a suitable jig or fixture, are subjected to a brazing operation by which the parts are united one with another. Similarly, the core assembly comprising the header plates 28 and 29, tubes 33 and baffles 34 is assembled and united by brazing. After the brazing operations, the core is slipped into the casing 10 and the plates 28 and 29 .secured thereto by welding. The end closure 12 'then is installed and welded in place, and in like manner the fixtures 24, 26, 39, 41 and 42 and the partitioning rings 43 and 44 are attached by welding.

Completing the assembly of parts is a plate 48 detachably mounted on the ring fixture 42 and mounting a check valve 49 arranged to admit a fluid flow into the chamber 47 of the valve casing but to deny a reverse flow. Further completing the assembly of parts is a valve unit 51 detachably mounted on the ring fixture 41 and combining therewith to close that end of the valve casing opposite the check valve 49. The unit 51 is in parta conventional thermostatic power valve assembly. In `general it comprises a housing in the interior of which is a bearing support 53 for a shaft 54 which `extends from one side of a case 55. From the other side of the case 55 extends another shaft 56 having a screw threaded connection with a stem 57 of a poppet type valve 58. Within the case 55 are two chambers 59 and 61 containing a substance having the property of expansion underheat and capable of exerting a relatively powerful expansive force. In the case of shaft 54, such force is applied axially thereof through a diaphragm 62 and a rubber plug 63. The material in chamber 61 is similarly applicable upon shaft 56 through a like diaphragm 64 and a rubber plug 65.

Outward or leftward motion of the shaft 54 is inhibited byy a cage 66 engaged by a shouldered part 67 on the shaft 54 and in turn bearing against one end of a relatively strong spring 68, the other end of which is seated in the bottom of housing 52. The force generated in chamber 59 normally is insufficient to compress the spring `68 so that the force tending to move the shaft 54 outward or to the left as viewed in Fig. l is resolved into a bodily shifting motion of the case 55 toward the right or away from cage 66. This motion serves to compress another spring 69 interposed between a snap ring on the case 55 and a stationary member 71 interposed between the case 66 and a lock ring 72 stationarily mounted in the internal wall of housing 52 and preventing expansion of the spring 68 beyond the degree illustrated. Compression of the spring 69 provides a force for return of the case 55 and recompressing of the lmaterial in chamber 59. The expansive force exerted in `chamber 61 is supplied to shaft 56 in a direction to extend the shaft to the right. The forces generated in `both chambers 59 and 61 accordingly complement one another and are such as to provide for a relatively long travel of the valve stern 57 to which, as before noted, the shaft 56 is connected. The shaft 56 is returned and the material in chamber 61 recompressed by a spring 73 in a cage 74, which spring is compressed by outward extending motion of the shaft 56 relative to the case 55.

The case 55 lies within chamber 45 in the valve casing and is surrounded by a sleeve 75 mounted at its one end on a shoulder on the housing 52 and staked thereto, as by a pin 76. The other end of the sleeve 75 is received in a counterbore 77 in the partitioning member 43 and unitarily mounts a plate 78 on the periphery thereof, which plate has a relatively close fit in the counterbore 77 made uid tight by a ring seal 79 set in the periphery of the plate 78. The plate 78 has a central boss 81 projecting into the chamber 46 and providing a sliding mount for the stem 57 of the valve 58. An annular recess 82 in the valve stem 57 mounts a ring seal 83 preventing the fiow of fiuid along the surface of the valve stem between the chambers 45 and 46.

The sleeve has an opening substantially registering with the opening 16 in the valve casing 11, in which is a circular defiector member 84. In the upper part of the sleeve 75, in substantially opposed relation to the deliector 84 and in line with the radial opening 37 in the casing 11, is a peripheral slot .85. The construction and arrangement of parts is such that fluid owing upward from the heat exchanger outlet chamber 32 into the chamber 45 of the valve casing is constrained to wash the casing 55 of the thermostatic valve assembly as it passes between inlet opening 16 of the valve casing and outlet opening 37.

The partitioning member 44 defines a seat for the valve 58 in surrounding relation to a straight sided cylindrical opening 86 therein. The working face of valve 58, or that side thereof facing the partitioning member 44, is formed with a frusto conical portion 8 and, outwardly thereof, a curved or contoured surface portion 88. The portion 88 is received within the opening 86 in the closed position of the valve, as seen in Fig. 2, and it will be observed defines with the wall of opening 86 an area 89 for ow of fluid from chamber 47 past the valve 58 into chamber 46. As is known, the rate of fiuid fiow through an opening is proportional to the area of the opening. Thus with a conventional poppet type valve in which the working surface is in the shape of a frustum of a cone the rate of opening is proportional to the movement of the valve and accordingly the rate of fluid flow is proportional to the movement of the valve. In the present instance, it is desirable, however, to provide for a change in ow rate which is not in direct proportion to the movement of the valve, it being the objective .to avoid instability in the movements of the valve and thereby continuous fluctuations in the controlled fluid temperature. The contoured valve surface hereof is such, it will be understood, that relatively small movements of the valve produce relatively small changes in the rate of fluid fiow past the valve and hence small variations in temperature. That is, ,the shape of the valve face is such .that the rate of change in the area 89 with respect to valve travel is reduced and thereby reducing the instability of the temperature controlled.

`Suitably installed as an engine accessory in the lubricant circulating `and fuel supply lines, the heat exchange apparatus is arranged to receive fuel through the opening 27 of `theheat exchanger casing, with such fuel passing through the heat exchange core, out of the heat exchanger casing `by way of connector device 14 and through chamber 45 of the valve casing where its temperature is sensed by the thermal material in the chambers 59 and 61 of the thermostatic valve assembly. Continuing `beyond the thermostatic valve assembly, the fuel leaves the heat transfer apparatus by way of opening 37 in the `valve casing and continues its ow to -the engine. Oil, heated by its passage through `the engine, is admitted to the apparatus by way of the check valve fitting `48 at one end ofthe valve casing 11. The oil flows into thechamber 47 and through opening 86 past j 'the casing and follows a circuitous route through the heat exchange core to the outlet opening and tting 24. The oil gives up some of its heat to the flowing fuel which thus has been warmed by the time it washes the thermostatic valve assembly in the valve casing. Assuming the valve 58 to stand normally open as indicated in Fig. l, a rising fuel temperature will result in an axial extending motion of the valve to reduce the open area between the contoured valve face 88 and the Wall of opening 86. The rate of ow of the oil to the heat exchange core accordingly drops off and there is a resultant decrease in the rate of warming of the fuel. The valve is constructed and arranged to stabilize at a selected fuel temperature, for example 65 and there will be corresponding adjustments of the valve 58 as the fuel temperature rises above and drops below this ligure.

The valve unit 51 is installed in the casing 11 as a subassembly and may he similarly removed for inspection and servicing. For servicing of the core, the end closures 12 and 25 can be removed for access to the ends of the core, whereby a broken tube can be removed and replaced or its ends plugged. The same or new end closures may then be reinstalled and re-welded in place.

In further regard to the core, the relatively dense arrangement of'the tubes, and the beaded structure thereof so materially raise the heat exchange efficiency that outlet opening 23 may be located opposite inlet opening 17 whereby substantially to reduce the pressure drop through the core, on the oil side.

What is claimed is: f

1. A light weight valve and heat exchanger combination, including an open ended sheet metal heat exchanger casing, an open ended sheet metal valve cosng in parallel adjacent relation to said heat exchanger casing a pair of hollow sheet metal devices interconnecting said casings and providing communication between the interiors thereof, said casings and said devices being joined together in a unitary assembly, closures for the ends of said casings, one closure in each of. said casings being open for ow of respectively different fluids therethrough, tube sheets installed in said heat exchanger casing on opposite sides of one of said pair of devices, the other vsaid device being located between the other one of said closures and an adjacent one of said tube sheets, tubes supported between said tube sheets to conduct a first uid from said one closure of said heat exchanger casing to said other device, partition means in said valve casing between the said one closure thereof and said one-device and other` partition means in said valve casing between said devices,

an outlet for said first uid from said valve casing communicating with the space between said other partition means and the other end closure in said valve casing, a passage through said partition means to conduct a second iiuid from the said one end closure of s aid valve casing to said one device and vthence to the interior of said heat exchanger casing between said tube sheets, a valve controlling the rate of ilow through said passage, means responding to a changing condition of said first fluid to position said valve, and an outlet for said second fluid from the interior of said heat exchanger casing.

2. A light weight valve and heat exchanger combination, including a heat exchanger casing, a valve casing in parallel adjacent relation to said heat exchanger casing,

said casings being joined together in a unitary assembly, a pair of spaced apart lateral passes intercommunicating the interiors of said casings, tube sheets installed insaid heat exchanger casing on opposite sides of one of said passes, the other one of said passes being located between one of said tube sheets and corresponding ends of said casings, said end being closed, tubes supported between said tube sheets, means to introduce a rst uid under pressure between the other one of said tube sheets and the opposite end of said heat exchanger casing, said first fluid owing through said tubes to the "said other one of said passes and being communicated thereby to the interior of said valvev casing, an outlet fromr said valve casing for said first fluid, a partition in said valve casing between the said other one of said passes and the opposite end of said casing, saidone pass communicating with the interior of said valve casing between the said opposite end thereof and said partition, means to introduce a second uid under pressure into said valve casing at said opposite end thereof, including a passage in said valve casing through which said second uid ows, a valve controlling the rate of flow through said passage, thermal means in said valve casing responding to a changing temperature of said first uid therein, a connection between said thermal means and said valve under control of said thermal means relatively to said passage, and an outlet for said second uid from the interior of said heat exchanger `casing between said tube UNITED STATES PATENT OFFICE CERTIFICATE 0F CRRECTION Patent No 2,864,589 December 16, 1958 Harry T. Booth et al.,

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line 37, for "Valve CostingH read m valve casing n; column 69 line 39, after "valveH insert -1- through sadlpartition to adjust said valve um;

signed and Sealed this 31st day 'of March i959n (SEAL) Attest:

KARL H AXLINE ROBERT C. WATSON Commissioner of Patents Attesting Ocer

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