US3534814A - Heat exchanger construction - Google Patents

Description

v United States Patent 111 5 4 [72] Inventor PeterN. Rena 56 Referen e Cit d 21 A I N m UNITED STATES PATENTS 1 1,667,257 4/1928 Hicks et al 219/540 [22] Flled June 9,

2,085,772 7/1937 Soverhlll 219/540X Division of Ser. No. 649,505, June 28, 1967, Pawn No 3,479 489 2,244,172 6/1941 Novak 165/ 185X 2,346,822 4/1944 Clancy l65/177X [45] Patented Oet.20, 1970 r 2,911,513 11/1959 MacCrackenW 219/530X [73] Asslgnee Amu'leanfiandardlnc.

1 3,479,489 11/1969 Zenz1 219/540 New York, New York a corporation of Delaware FOREIGN PATENTS Bil/16,995 9/1963 Japan 165/172 Primary Examiner- Volodymyr Y. Mayewsky AttorneyJefferson Ehrlich [54] HEAT EXCHANGER CONSTRUCTION lo claimsonwhgm ABSTRACT: A heat-transmitting structure having a spirally [52] US. Cl. 165/172, twisted pair of longitudinal heat-conductive tubes each con- 165/177, 165/181 219/540 structed for eonducting fluids for fluid thermal application. In- [51] lnt.Cl .1 F28! l/10 terleaved between the spiral multitude of radially extending [50] Field Search 2l /530, heat conductors there are in thermal contact with twisted 540, 165,430; 165/172. 177, 185, 181, 182-184; pairs of the tubes. The radial conductors serve to dissipate heat generated or transmitted by the twisted pairs of the tubes.

Patented 0a. 20,1910 3,534,814

INVENTOR Peter N. Renzi ATTORNEY tion, an; "proves w 'Ihe invention utilizes a longitudinal resistance element com- "prised of a twisted wire core which includes so-called spine or metal bristles frictionally or otherwise retained between the spirals of the wire core and which transmit the generated or transmittedheat'laterally by conduction along the paths of the ters.

' ing device component of FIG. 1;

BEA EEXCHANGER cousrauc'non This application is a division of application Ser. No. 649,595, filed Jurie 28, 1967, now US. Pat. No; 3,479,489, issued NovI I8, I 169 entitled Heat Exchanger Construction.

This inventiorirelate'sto heating devices having improved heat transfer properties. More specifically, this invention relates to eliectrical'heating elements which may be formed by twisted. electrical resistance, heating cores and having heat transmission elementssecured between the twists to dissipate the heat. ,Asan' alternative, the heating elements may be' formed of twisted tubesfor transporting heating fluids and employing heat transmission e'lementsto dissipate or relay the heat conveyed by the heating fluids to the adjoining space. i

The configuration' of conventional electrical heating elements, for e'xainple, is usually fixed within relatively narrow limits as dictated by performance, cost considerations, and

specified and electrical limits. Some conventional comprised of an elongated cylindrical tube which surrounds a resistance heating element disposed along the axis of the sheath. The heating element may consist of a straight wireor bar, and it may be supportedcquidistantly between the inner walls of {the sheath-by aninsulating material suchas magnesium'oxideQTo iiic'rea'se the thermal dissipation of the heating element, externiil radial fins may be added along: the length of the outer surface ofthe sheath. The amount of heat that can be "dissipated per unit "length'of resistance heater wire is a function of the exterior surface a'reaof the sheath and-of the difference in temperature between the surface of the sheath n e surrounding medium. I

' The two conductors and 12 may be any electrical 'h'ea'tersjgenerally employ a metallic outer sheath In accordance ith'one embodiment'of thepresent invenectrica'l heater is-provided which substantially. im-

nih'ehe'at dissipation from the resistance element.

metal bristles. I

"The metal bristles serve effectivelytoincrease'the exterior surface areaof the resistance heating 'el'ement'to permit an improved dissipa'tibn ofheat perunit length without 'materially affecting its electrical properties. The design ofthe twisted .wire core'is simple' a'nd'may be mass-produced by automatic machineltcchnilques. Due'to its similarity inconstruction to twisted bristle brushes, it may also be feasible to use many of the same techniques in constructing the heater construction of this invention. w

It is therefore a general object according to the present invention toprovide a heatingdevice which has improved heat conduction properties and permits variation in design parame? It isanot'her general object according to thepresentinven- 1 tion to provideaheatin'gdevice which utilizes a twisted wire core and which employs heat tra'nsmis'sionelements secured between the twists'to substantially increase the amount ofzheat which may be dissipated per unit length,

It is another general object according to the present invento-manufactureiandreliuble inoperation. I

Other ob cts' and 'features' ofthe present invention will become'apparent' from the following detailed description'considered inconncction with the accompanying drawings which 3 disclose 'various embodiments of 'the'present-invcntion. It

should be understood, however; thatthe drawings Of-{I'lCxdiS- closed embodiments are designed for the purpose of illustration' o nlyjaridpii ot as-adcfinition of the limits of the-invention as to'whiqh' refeience'should be made in the appended claims.

' cal heating device of FIG.

and

FIG.- 2 is a schematic of a cross-sectional view taken along tion according to this invention;

FIG; 3 is a schematic of. a cross-sectional view 2 taken along the line ,3-3 of FIG. 2;

the. longitudinal dimension of the electrical heating combihaa FIG. 4. is a schematic of a cross-sectionalview vention.

Referring to gated metal tube. substantially along the axis of sheath 10 is a. wire core ,comprised of two electrical conduc tors l1 and 12.

propriate materials which, for electrical...he

might be nichrome, platinum, .chrome-alumei,

ductors might be embedded in insulating material 'l3' s uch' as magnesium oxide, etc.; and the sheath material might conel, stainless steel, etc.

Referring more particularly to FIG. 2, two such sheathed tubes or heating devices 100 and 10b, eachfencasinga pair of electrical conductors such as 11 and 12, are twisted or wrapped about each other fairly tightly within' the physical limits of the. materials of the construction. Interleaved and locked between the spirals or twists of the conductor cores l0a .and 10b are a multitudeof heatconductors ordissipators '14. Heat conductors 14 are in good physical and thermalcon tact withthe sheaths of the electrical conductor'cores loa and 10b. i As one moveslongitudinally along the length of cores 10a :and 10b, conductors 14 are seen directed throughalmost every degree of arc along the imaginary envelope of the =.tips or The finsv 14 also are employed in similar fashion in this em.

bodiment for heat dissipation purposes. Twisting the tubes or' pipes about each other must be performed with care to avoid any rupture of the tubes or pipes.

As already stated, the heat conductors l4 maybe constructed of any materials having good heat conduction or dissipation properties, such as aluminum, copper and. the like. The 'heatconductors may, if desired, be composed of appropriate synthetic materials which have good heat conduction properties. The heat conductors l4 obviously need not be metallic. When so designed, then whatever their composition, they can be employed in an electrical conduction system such :as that shown in FIG; 2,.or in a fluid heat exchanger system ;such as thatshown in FIG. 4, to dissipate the transmitted heat into the adjoining space or room or, in the case wherein a cold tion to p ovi e-a heating device which is-simple in design, easy V fluid is circulated through hollow tubes 10a and 10b as in FIG. 4,- to absorb heat from the environment.

The twisted wire core and the heat-conducting bristles may be formed separately on automatic machines and assembled lr'fthe drawings, wherein similar -'reference characters 0 denote I lar elements throughout the several views: FIG-f is a perspective view of a length of a heating'device j fqrn ring aco "iie'n't bf the arrangementaccording to the invention; I

" no: rafts a'ieh mic bra cross-sectional view of the heatinto, the combination shown in FIGS. 2, 3 and 4.

If conductor cores 10a and 10b are to carry heating or cool- .ingfluids, as;indicated in FIG. 4, suitable fluid connections or piping may obviously be provided in any well known manner at'the ends of the conductor cores. Similarly, if conductor cores 10a and 10b are to serve as electrical resistance heaters,

as in FIG. 2, electrical terminals may obviously beprovidedin any-well known manner at one or both ends of the core constructions according to the invention. As it is' readily feasible to sufficiently insulate conductor 11 from conductor 12 in either of the electrical heater cores, it is possible to drive a se- -ries electrical current over a return path through the conductors by connecting conductors l1 and 12 together at one end of the elec'itri v talten along the longitudinal dimension of another embodimentj'of the inf the FIGS, and particularlyFlGS. l and laf there is shown a component of a heating device according to" the invention having an, outer sheath lo cons'ist'ing of an elonof the core construction. The conductors 11 and 12 may also be connected in parallel by providing electrical terminals at both ends of the heating core element. y

it is obvious from the above disclosure that the construction of this invention may embody coaxial cable units each embodying one or more conductors such as 11. And the cable units need not'be wrapped or twisted about each other. However, the heat conductors may be either metallic or nonmetallic elements having relatively good heat transmission qualities and may be fastened or otherwise affixed to or between the cable units so as to conduct the electrically generated heat from the cable units to the adjoining space. The sheaths of the cableunits need not be metallic. Furthennore, the invention is equally applicable to a similar unwrapped or untwisted pipe structure in which a fluid conveyor is transported. The heat dissipators will relay the heat of the fluid to the outer space or absorb heat from the outer space and conduct it to a cold fluid in the tubes.

Each twisted core unit, such as 104, need not be limited to one having but two conductors, but the unit may include any I I desired number of conductors constructed from fluid tubing or from electrical resistance heating wire, as the case may be.

' Furthermore, each combination of core units need not be limited to two. as shown in FIGS. 2 and 4, but the combination may embody any desired number of core units wrapped about each other to grip and maintain numerous heat conductors suchas '14. The relative tightness of the twists will lock the heat conductors 14 in substantially immovable positions a between the core units.

Although the heat transmission elements 14 have been shown and described as radial elements, naturally these elements 14 may be positioned or held at any desired angle or j orientation with respect the longitudinal path of the elements a and 10b. The angle or orientation may be perpendicular to the general path of the elements 10a and 10b, or positioned 7 considered in arriving at a desired design of a heat transfer device for a particular installation or operation and .these'factors would be considered in connection with the number 'of teristics for the installation or operation.

twisted core elements and their physical and thermal charac- While only a few embodiments of the present inventionhave been shown and described, it will be understood that many other changes and modifications may be madetherein without departing from the spirit andscope of the, invention as defined by the appended claims. 5 g

lclaim: V I

1. A heat transfer apparatus co mpris ing; two' longitudinal heat-conducting tubes helically twisted aboutea it other and transmitting therethroughheat-conductivefliid, aridal' mul titude of linear heat transmission elements held and secured between the twists ofsaidtubes. i

2. The apparatus as recitedin claim wherein each of said twisted tubes comprises one or more cores fofvthe conduction offluids. a

3. The apparatus as recited heat transmission elements al.

4. The combination of a'pai' of longitudinai heating conducting tubes helically twisted about each other and contihuously transmitting heated fluids and a multitude of linear fins interposed between and held by the tubes for transferring heat clai rn 1 \wghe ein'each of said of heat-conducting materifrom said tubes into the surrounding space 5. A heat transfer'device comprising a pair of linear heatconducting conduits helically twiste'dabodteach other and continuously transmitting fluid which carries heat, a multitude of linear heat-transmitting fins positioned in physical contact with said linear conduits substantially throughout the length of the conduits, said fins being held between and "maintained substantially perpendicular to said linear conduits'tind dissipating heat developed within said linear conduitsl 6. A heat transfer device according to claim 5, in which the fins are made of a material which is classifiable both as a good electrical insulator and as a good heat transmitter.

7. A heat transfer device according to claim 5, inwhich-the fins are composed of boron nitride. E

8. A heat transfer device according to claim 5, iri'which the transmitting fins are bilateral heat-cohducting' m edia which will transfer heat from the surrounding space to the linear conduitswhen the surrounding space is ataihighertemperature than those of the linear conduits andlwill transfer heat from the linear conduits to the surrou nding spac'e when the temperature of the linear conduits exceeds that of the surrounding space.

9. A heat transfer device for maintaining a spatial region within predetermined temperature limits, comprising two linearly arranged heat-conducting conduit elements'helically twisted about each other and transmitting fluids, a multitude of linear fins having good heat-transmitting properties, and means for fastening said fins between said conduit elements to hold and maintain said fins substantially perpendicular to said conduit elements so that said fins may transfer heat between said conduit elements and the spatial region.

l0. A'heat transfer device according to claim 9, in which the fins are made of heat-conducting metals.

Images