CA1140533A

CA1140533A - Hollow fibers of synthetic polymers

Info

Publication number: CA1140533A
Application number: CA000347724A
Authority: CA
Inventors: Helmut Stohr; Klaus Gerlach; Erich Kessler; Klaus Schneider; Karl Ostertag
Original assignee: Akzo NV
Current assignee: Akzo NV
Priority date: 1979-03-17
Filing date: 1980-03-14
Publication date: 1983-02-01
Also published as: GB2047874B; ES489544A1; BE882224R; IT8048116A0; JPS6067103U; CH650696A5; FR2451952A2; JPS56308A; ATA139180A; AT380403B; IT1143117B; FR2451952B2; GB2047874A

Abstract

TITLE: AN APPARATUS IN WHICH HEAT IS TRANSFERRED
THROUGH HOLLOW THREADS AS WELL AS HOLLOW
THREADS SUITABLE FOR THIS PURPOSE

ABSTRACT
An apparatus for transferring heat by means of hollow threads composed of synthetic polymers having from 10 to 90% by volume of inter-comminunicating pores and an even surface containing open pores. The proportion of the surface of the threads which is open amounts to from 10 to 90%.

Description

iLlL~D 533 The inven-tion relates -to an apparatus in whi.ch heat is transferred -through hollow -threads, as well as hollow threads sui-table for -this purpose.
TIeat e~changers composed o e hollow threacls or hollow -fibres ar0 known, in wh:ich the hollow -threacls or hollow fibres are arrangèd in s-trai.ght lines parallel . to each o-ther and at distances from each o-ther.
Porous hollow threads and the producti.on thereof have already been proposed. Their use as -filters, membrane carriers -for separat:i.on purposes, substrate carriers or oxygenators has also been proposed.
I~ the already proposed method, polymers can be shaped in a simple manner into an extrudible spinning composition and this spinning compost-tion can simul-taneously be ex-truded and solidified witholl-t complicated spinning -techniques and spinning ba~hs having to be employed~ Moreover, this method allows threads having adjustable porosity,perviousness and permeab.Llity to be obtained merely by varying the operation parameters. The porous hollow -threads produced by this m~thod are dis-tinguished -from -the known -threads by a favollrab:le open sur:eace, whereby bo-th the o~ter and -the :inner wa:Ll of tlie ho~Llow thread has a s-tructure WtliC}I :is prov:ided w:ith open pores but is neverthe:less even. The pornus hollow threads already proposed call -therefore be used in -the te~ti:le and ,'.~ .

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ccmmercial fields, as well as in the medical field, for examplet in separation processes and are particularly suitable as filters, microfilters, membrane carriers and as supFort substrate for certain substances.
With the method already proposed for producing porous hollow threads, a hc~ogeneous mixture of at least two comFonents, one comFonent being a fusible polymer and the other comFonent a liquid which is inert toward the polymer, both components forming a binary system which has a range of complete miscibility in the liquid state of matter and a range with mixing gaps, is extruded at a temperature above the disinte-gration temperat~res into a bath containing the inert liquid of the extruded cGmponent mixture and having a temperature below the disintegration temperature, and the hollow thread structure formed solidifies.
With this method, the hollow fibre structure formed, once it has solidified, can be washed out using a solvent, in particular acetone, and/or an optionally heated air gap can be maintained between the outlet face of t~ extrusion tool and the surface of the bath and/or the homcgeneous mixture can be extruded directly into the bath and/or a temperature-staggered bath can be used which can consist of one or more parts having a temperature grzdient such that the temperature decreases continuously from the beginning to the outlet end of the "`` i~L L~ 3 spinning ba-th and~or two or more separa-te baths ca'1. be used which each hava a differen-t tempera-ture, and/or the ~ath can 'be at a temperature which is at leas-t 100 C lower t:han -the disintegration -temperature of -the b~inary composition use~ and/or t.lle homogeneous mixture can a:Lso be ex-truded ini-lially in-to a spinning -tu'be proceding -the bath and i1lled w:i-th 'batll flllid and/or homogeneous mixtures of Irom l.0 to 9()~0 by weight O:r polymer and ~rom 90 to 10~ by weigh-t of inert liquid can be extruded, andjor ~olypropylene is use~ as polymer and NN-bis-(2-hydroxyethyl)-hexadecyl-amine can be used as inert liquid and/or the -two componen-ts, namely the mol-ten polyme:r and -the inert liquid, can pre:Eerably be mixed cont:inuonsly prior to ex-trusion, whereby :it is desirable for m:ixing -to -take place :immedia-tely before extrusion, and/or -the mixture can 'be fur:ther homogeni~ed prior to ex-trusion, a pin mixer being particularly suitable for mixillg p'urposes.
In order to carry Ollt -the method and -to produce the porous hollow th:reads already proposed, it is possible -to use conventional per se, in par-ticular fibre-:form:ing micro-molecular subs-tances, par-t:icularly synthet:ic po:lymers which' are o'btained, for example, by polymerisa-t:ioll, polyacl('li-t:ion or polycondensa-t:ion, a conditi.on bei.ng that the po:Lymer be I'us:ible, i.e can pass into -the :liquid sta-te o:~ matter withollt ~ .

disintegratillg and ~orms with a l.iquid which is iner-t toward it a b:inary sys-tem which has a range of comple-te misc:ib~ ty in the liqllid state O:r mat-ter and also s-till has a range with mixing gaps :in the :liquid s-tate of matter.
In order -to earry ou-t -the me-thod alreacly p:roposecl, :it is not absolutely essen-t:i.al :Cor -the -t;wo componen-ts each s-till to have considerable solubi.:lity rela-tive -to -the other componen-t in -the -two-phase range.
Marginal solubility in -the liquid -two-phase range :is su~ficient in many cases. However, i-t is importan-t - for -the -two componen-ts still to form two liquid phases next -to each other in -the liquid s-ta-te~ ln this respec-t, -the sys-tems which ,as alreacly mentionecl, L5 can be used di.:Efer from those sys-tems in which the dissolved po:Lymer precipi-tates d.i.rectly as a soli.d suhs-tance when -the -tempera-ture is lowered wi-thou-t fi:rstly pass:ing -through the ].iquid sta-te during coo:Ling.
As already proposed, conven-tional fusible .20 polymers can be used such as -the polymers, po:Lye-thylene, polypropylene, polyvinyl chloride, polyacryla-tes, polycaprolac-tam as well as corresponding copolymers and o-ther ob-tainable by polymerisation; po:lyconc-lensa-tion polymers such as po:lyethy].ene -terep}lthalate, polybll-ty:lene terepllthalate, po:Lyamide-6,6 polyplleny]ene ox:icle and polyaddi-tion polyme:rs sucll as polyu:re-thanes and polyureas.
Su:i-tahle inert :I:iqu:ids basical:ly :inclllde, as proposecl, all those liquids which -form a binary system of the above-mentionecl type wi-th -the polymer in the liquid sta-te, inert toward -the polymer means, in this contex-t, tha-t the liquld does no-t effec-t noticeable decomposition of the polymer or react wi-th -the polymer itself wi-thin a short periocl O-r time.
~ Ithough the phase diagram o-F -the aniline/
hexane system mentioned in the descrip-tion o:E tlle proposed method shows the ratios -for a binary mixture consisting in and for i-tself of only two essentially pure uniform subs-tances, the term binary system, as mentioned therein, sh~uld no-t stric-tly apply to mixtures of soley -two pure uniform subs-tances. The average skilled man knows -that a polymer is composed of a plurality i5 f molecules of differing molecular weigh-t distribution as describecl therein should be considered as on~
component, and the same applies to mixed polymers. Under certain circumstances, polymer mix-tures can even behave like a uni-form component, form a single-phase rnix-ture with an inert solven-t and separate in-to two liquid phases below the critical temperature. T~owever prefer-ably only one polymer is usecl.
In addition, the liquid neecl not necessarily be completely pure and represent a completely llniform substance. Thus, it is often immater1al i relativeLy small quantlties of impurities and optiollally aLso propor-tions of homologous compounds as caused by mass-production, are added.

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In order -to put -the me-thod already proposed into practise, a homogeneous mix-tu:re is produced from the -two componen-ts at the necessary tempera-tures. This can be effected by mixing -the i.ner-t liquid wi-th the comminu-ted polymer and heating i-t -to sui-table -tempera-tures, thus ensuring suita~le thorough mixing.
In another sui.table method, the -two componen-ts are brough-t to the.required -temperature separa-tely and the two components mixed together continuously in 10 the d.esired proportion jus-t pr:ior to extrusion. This mixing process can -take place :in a pill mixe:r which is preferably arranged between the metcr:ing pumps for -the individual components and the spinning pump. Subsequen-t homogeniza-tion may be advisab].e. Moreover, :i-t i.9 often 15 adv:isable to aera-te the homogeneous ~ix-ture by app:lying a sui-table vacuum prior -to ex-trusion.
The ra-tio of polymer to inert liquid in -the spinning composition can be varied wi-thi.n wide limits The pore volume :i.n -the interior and also -the surface 20 structu-re as well as the number of opem pores on the sur:faces of -the hollow thread ob-tained can be con-trolled -to a la:rge extend by adjus-t:ing the rat:io of polymcr -to :iner-t liquid. Sui-table hollow threads can be obtained in th:i.s way :~or a w:ide var:iety of IlSeS.
I-t is generally su:Eficient for t.he -tempera-ture o-f -the homogeneous mixture pri.or to ex-trusion to lie .

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only a fe~ degrees above the cr:i-tica:L -temperature or above -the disintegration -tempera-ture depending on the respec-tive composi-tion.
By increasing the dif-ference between the temperature of the homogeneous mix-ture to be extruded and the disintegra-tion tempera-ture, however, interesting effec-ts can be achieved in -the struc-ture o:l' the threads o'btained.
The homogeneous spinning composi-tion is -then extruded into a bath containing the inert liquid of the extruded componen-t mix-ture and having a tempera-ture below the disin-tegration -temperature. The bath preferab'ly consists completely or mainly of the iner-t liquicl which is also present in the ex-truded mixture.
i5 The'temperature of the bath lies below the mixing temperatures of the binary mixture used, i.e below the temperature above which -the -two components can be mi~ed -together completely homogenously. The -temperature oE the ba-th preferably lies at least 100C

2~ below -the disin-tegration temperature of the mixture ~secl.
The temperature can also be sufllciently 'Low to move in the range in whic}l a solid phase occurs depending on the phase diagram applying to the binary sys-tem.
If -the tempera-ture of the bath is so 'high that the liquid two-phases range prevails, :it is necessary to sol:id.ify the resultant thread struclure, as soon as possib1e a~ld thi.s can be done hy suitably :reducing -the tempe:ratu:re after a certain per.iod withi.n the . bath. It is :important for -the ex-truded mixture s-ti.ll to be single-phased be~ore it enter!s the ba-th, i.e. for subs-tantially.no disin-tegration into two .phases have ye-t occurred.
In certain cases9 it has proven advantageous that the bath be preceded by a spinning -tu'be which is also filled with the ba-th liquid and which is i.mmersed in the spinning bath. The spinn-ing -tube can have a conventioanl spi.nning hopper a-t its inlet end and can be curved at its lower end in order to ': make :it easie:r to talce o-ff -the thread through the 1.5 ba-th.
The spinning -tube can be filled by means ol a levelling vessel surrounding -the spinning tube by over-flow into the spinning tube To completely :Eill ancl maintain the leve:l in -the spinning tube, i-t is necessary to supply to this levelling vessel more bath liquid from the main reservior than flows through the splnning tube. rrh.e excess quantity of bath :Liqu:id can be recirc11lated into -the main reservo:ir -through a second over:r:low on the 1.eve1'1ing vcsse'l. Tl1e ma.in reservoi1 and :levelling vessel can be thermostat.ical:ly controlled.

3~ i33 Once -the thread has passed out o:E the spinning bath, it can be washed out with a sui-table extractant.
A number of solven-ts such as, :for example, ace-tone, cyclohexane, ethanoL etc., as well as mix-tures of these liquids are suitable -L'or extrac-tion puxposes.
In some cases, i-t is not necessary to wash out -the -thread, particularly if -the inert liquid used itself impar-ts additional proper-ties -to -the thread which are intended for its subsequent use or is -to fulfil a func-tion i-tsel:E. Thus, -for example, li~uids which exert an antistatic e-fEect on -the -thread or act as lubrica~-ts can be usecl.
It has proven beneficial for a number of applications to maintain an air gap between -the outlet face o-E the ex-trusion t~ool, i.e. the outle-t face of, for example, a corresponding hoLlow thread nozzle and the surface of -the bath The struc-ture of -the hollow thread ob-tained, in particular its surface, ' can be in-fluenced by varying -the air gap.
It has been found that the number of open pores in the sur:Eace can be reduced by lengthen-ing the air gap and increased by shortening it. The d-iameter of the po-res also decreases as t;he air gap increases.
The air gap can be heated, preferab'Ly to a ~5 temperatllre above the dis-in-tegrat:ion tempela-tllre oE
-tlle ex-tru-led IlliX tll r~e .
' The air gap is generally at leas-t L mm wicle and can assume a length of up to about 10 Clll, aepellaing r~J
~1~0~33 on -the operat:irlg conditions. I t is important for no, or at least no significallt, disintegrat:ion in-to two liquid phases -to occur in the air gap 'be:Eore en-try into the bath and, as rnentioned, -this can be controlled by -the s}-lor-tness o:f the path or by heà-ting. I-t is however possible -to coun-terac-t premature disintegration by increasing -the ou-tle t speed a-t the nozzle .
In a par-t icular embod imen-t o-f the rme-thod already proposed, however, the homogeneous mix-ture is ex-truded directly into the bat~l, open pores having a maximum d:iameter being formed on -the sur:Eace.
The hollow -threads ob-i;ained can be used par-ticlllarly well as -fil-ters. In par-ticular, they can be used during micro-f i l tra-tion . The -thr eads are particularly sui table in -the medical sphere, where they can for example be used ]n -the filtration of blood, for example fol separating blood, lamella, because of -their selectivity in separa-ting hacteria.
They are also very sui table as oxygenators, w'here oxygen -flows tllrough the interior of the hollow -threads while the exterior is surrounded by b100d.
The hollow threads can also l)e used as nle~ arlc carriers :Eor a mlmber of purl)oses. Due -to their excellent everl surEace strllcture wi-th open pores, they can :in Eact be coa-ted ex-tremeLy we]:l with a firmly adhering thin layer o:E a mate:rial acting as membrane l;his frequently being efl`ected by coating or spray-ing wi-th sui table film-forming solu tions . In fac t, due to - , ~

ii33 i-ts exce:llerl-t sur:Cace properties, no-t onl.y does the resul-tant membrane layer adhere very well to -the hollow threads, but the co.ating solu-t;.on can be appliecl very unifor~ly as a thin skin wi-thou-t -the solu-tion penetra-ting or even dropping i.n-to the in-terior of the hollow thread, so very e-ffec-t:ive membranes -can be procluced for a wide varie-ty of applica-tions.
As a resul-t o~ their particular sur-face s-tructure and -the struc-ture inside the hollow threads, iO they are also eminently sui-table as subs-tra-te for certain substances. Thus, -the -threads can be impregna-ted with antis-ta-tic agents which are used as iner-t liquid during the spinning process, or -the agent can be introcluced into -the thread struc-ture ~Later on af-ter production of -the -thread by -treatment for example by impregna-tionO I-t is also possible to introduce -the active substance in-to -the itl-ternal con-tinuous cavi-ty of the -thread.
In -this way, composi-tions having a long term efrec-t can be obtained, which slowly give llp -the absorbed ac-t:ive ingredien-t. Conversely9 -the hollow threads can also be used for adsorbing mater-ia:ls.
The proposecl hollow -th:reads are availab:Le :in a w:ide range of diolensions. Tlllls, ex-ternal diame-ters f up to several mi:llime-tres can be ach:i.evecl. The wal]. tll:i.cl~nesses are ec~ually w:iclely variable and can l-ie, for example, be-tween 2() niicrons and abou-t l -to 2mm.

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The pores in the propose(l hollow -threacls can have a w:ide variety of shapes. Thus, they can be roundish or oblong and cQmmunicate Wi't}l each other, at times -thl~ough snlall connec-ting cavi-ties and at o-ther -t:imes by passing directly :irlto each o-ther. Even wi-th hollow -threads o'b-tained rrom mi~-tures containing only a'bou-t 30~ o:~ polymers t}~e polymer can still be the matrix in which -the individual pores are distributed and f'orm more or less discre-te bu-t interconnec-ting iO cavities. Conversely? s-tructures can also be formed in which the hollow cavities form the ma-tri~ in a similar manner -to non-woven -fabrics and the polymer subs-tance is arranged in an a]mos-t fibrillar manner.
~he -transi-tions between these -two s-tructures are flowing and are some-times diffused. The struc-tural shapes can also be influenced 'by o-ther opera-ting parameters such as take off s~eed, cooling speed or drafting benea-th the nozzle.
The proposed hollow -threads are al~o dist:inguished in particular by high permeability towald gases SUCil as nitrogen or air. The permeabi~i-ty can be indicated by -the so-called permeabili-ty coeffic:ient K, as discussed in more detail :in -tlle boolc FLow or ELuicls throllgh Porous Materials by R E. Co'l'lins, pu'blishe(l by ~einhold Publ:ishing Corp., New York, 1961 on page :L0. K :is define(l as K :: Q . ~, wherein Q represents the A(AP/h) volwnetric rate oi' flow per a unit -time (for example , 15~,~

m3/s), n represents -the v:iscos.i.-ty of -the fl.owing meclium (Pa..s), A represen-ts the average area through which the gas issues, P represents i,he pressure difference (Pa~ and h represents the wa].l -thickness of the threads.
The permeability coeff:icient of -the hollow .threads amounts to at leas-t lO.iO i2 cm2 pre:ferably .at least 22.10 i2 cm2. Values above 100.10 12 cm2 can be attained.
1.0 The coefficient is measllrecl in -the -following manner:
several 3i, cm long hollow -threads are embedcled at the:ir two encls in two 5 cm long PVC -tubes with the aid o:f a curable polyurethane composition. Once -the polyurethane has curecl, a PVC tube i.s cut ancl the exposecd openings are joined to a nitrogen bot-tle 'by means of a feed pipe and the end of -the ot:her tube is sealed tigh-t by a s-topper. The air issu.ing through t~le -t}lreads is measurecl wi-th -the aid of flow me-ter.
Wi-th the proposed hollow threads wh:ich have been procduced from a mi.x-ture of 30~ by weigh-t of polypropylene and 70~ by weigh-t o-L' NN-b:i.s-(2-hyclroxyethyl)-hexadecy:l.amine wllil.e maintain:ing all a:i:r.gap ~etween tlle nozz'le ancl bath., -the :fol.:l.owing valuos cou.ld bc :t'ound:
,25 ~ LO L2clll2) Air Gap ~mm) ' 22 20 The hollow -th:reads can also be used in insu~ator and ~ 3 3 - i5 I,exti:le ap~pl;.cat:ions.
A sui-ta'ble apparatus for producing -the proposed hollow threacls -is-a thermosta-tically con-trollable con-tainer, from which the iner-t liquid is me-terecl in-to a mixer hy means O:r a dou'ble piston pUlllp and a second - hea-ter. A :first hea-ter is usecl ~or preminary heating Polypropylene passes from a ch-ip container via an extruder and a ~irst gear pumpl:in-to the mixer, from which a hollow -thread nozzle is ed via a second gear pump and supp:Lied with -the necessary quantity o-f nitrogen via a Rotameter. The issuing mass passes via an air gap into a spinning -tube which is provided with a spinning'hopper and is supplied w:i-th :inert liquid -from a main reservoir via a levelling vessel.
rrhe spinning tube llas a bend a-t its lower end and -the threads are wound a-fter leaving -the ba-th.
The Eollowing embodi,ment o:E the method alleady proposed has also been recommencled;
Some polypropylene having a melting i.ndex o:~
1.5 g/10 min, is mel-tect in an e~trucler at a heating -temperature o~ -rom 260 .to 280C and is metered via a gear pump into a very e-~lecti.ve pin mixer.

Some NN-b:is-(hydroxye-thy:L)hexade~cyl am:i.ne :is s:i.mul-taneollsly p-r;elleated to :L35C :in a passage heate:r .25 by means of a doub:le p:is-ton pum}) and mel;e:rect v,ia a .' separa-te pi.pe also into tlle m:ixer.

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T'he mi.xing ratio o:f polypropylene:amine :is 30.70 rrhe mixer speecl is adjus-ted to 40V rplll.

A:f-ter passi,ng -through the mixer, the two substances S;~3 wh-ich have become homogeneous are extruded -througll a gear pulnp :in a quantity of i5g/m-in :into a hol~low -thread nozzle having an inte:rnal. diameter o:f 2000 r~m and a free anmllar gap of ~00 ~m. The hollow -thread is -formed by add:ing 4 l/h of nitrogen in-to -tlle gas capill:iary of the nozzle.
The i.ssuing mol-ten -th:reacl plunges after a free fall of 3 min into the sp:;nning funnel filled wi-th amine acting as precipitat:ion bath, flows Wit}l the precipitan-t -through the subsequen-t sp:i.nning -tube having a diameter of 8 mm antl -the length of ~-~00 mm and is woulld on a winding unit a:Eter passing a-t 7lll/m:in througil a subsequent spinning ba-th which is L m long.
The hollow thread obtainecl is extrac-ted wi-th alcohol 15 and ~reed from amine. The hollow -thread has an exter~lal diameter of 2200 l~m and an internal diameter of 140() l~m.
A cavity-forming ~luid, in particular a po~e-Iorming liquid or a gas can be ~lown into the hollow tllread du:ri.ng -the spinning of -the hollow thread to produce stable hollow threads hav:ing large external diamensions and very snall wall thickness.
I-t has now surpris:ingly been found that the already proposed porous hollow t.hreads or :fibres are al.so par-t:icularly well suitod, in add.ition l;o the already ment:ioned appl:ications, -to the -transfer Or heat, part:icularl~ if they have p:roperties and/or a shape wh:ich i.ncrease the:ir thermal concluc-tivi-ty and/o:r t~lei.r hea-t transmiss:ion and/or .

their heat transfer and if they are arranged, utilising their flexibility, in such a-way that the apparatuses produced from porous hollow threads of this type have a greater resis-tance to external mechanical stresses so that they guarantee an undiminished heat -transfer capaci-ty even after prolonged operation.
In the case of a liquid which is to be cooled and which is flowing through the porous hollow threads, it is par-ticularly advantageous if, in addition to the heat transfer through thermal conductivity taking place -through the non-porous portions of the hollow thread wall, a proportion of the liquid flowing through the porous hollow threads flows - outwards through the pores and evaporates there, i.e. on the external surface of the porous hollow threa~s, so that the necessary vaporisation energy is removed from the proportion of -the liquid remaining in the interior of the hollow thread and is thus cooled.
An objec-t of the present invention is to i~prove the k~own heat exchangers composed of hollow threads with respect to their heat transfer capacity as well as their serviceability and to provide an appara-tus in which heat is transferred which, with regard both to its production and its serviceability and heat transfer cayaci-ty, does not have the disadvantages of conven-tional hea-t exchangers produced from the known hollow threads and which can be .. _.. ..

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produced in a simple and rapid manner.
Accordi.ng to -the invention, -the:re is provided an appara-tus for -transferring hea-t comprising hollow threads composed of synthe-tic polymers having 10 -to 90% by volllme o-f in-ter-communica-ting pores and an even surface conta.ining open pores, -the propor-tion of the surface which is open amoun-ting -to from 10 -to 90~.
- ~ccording to a second aspect o-f the inven-tion -there is also provided a hollow thread composed of iO syn-thetic polymers con-taining from 10 to 90~ by volume of inter-communicating pores and an even sur:face having open pores, the propor-tion of -the openings in the surface amoun-ting -to :~rom 10 to 90~, wherein a layer which ac-ts as a membrane is apl)lied -to l;he hollow -threads and/or -the hollow -threads con-tain graphi-te, me-tal par-ticles, -fillers, stabilisers, addi-tives, carbon bla~k or dye pigmen-ts or any combi-na-tion -thereo~, and/or the hol:low threads have a subs-tan-tial:ly circula~r cross-section w-ith an external : 20 diameter -fa:lling within the range of 0.1 -to 4 mm and/or . the llollow -threads have a wall th:ickness falling in -the ; range of -from 20 -to 5 ~lm and/or -the hol.low threads are -inte.rnally andjor externally pro:r-i:led and/o:r the llollow -threa(ls have a cross sect:i.on wllicll changes .cont.inuously or :interm:i.-ttently, :in shar)e and/or s:lze in its l:ongtudinal direc-tiorl and/or the ho:llow threads COllSi S t of two or more componen-ts and/or :in that only a proportion of the componen-ts is porous.

On the one hand -the fLexil-ili-ty of the porous hollow threads is u-tilised by means of tlle design of the appara-tus according to -the inven-tion and, on the o-ther hand, the special design of the already proposed porons hollow threads results in an increase in thermal conductivi-ty and/or hea-t transmission In a particularly preferred embodiment of -the apparatus according to the inven-tion3 each individual porous hollow thread is arranged over the majority iO of its length, preferal-~ly over i-ts enti~e len~th and/or -the majori-ty of all porous hollow -threads, preferalll~
the en-tirety of all porous hollow -threads is arranged in -tlle form of reglllar and/or irreglllar loops.
Apparatus of -the type according -to the iuven-tion, in which hea-t is -transCerred, do no-t have the disadvantages of -the known heat exchangers composed of hollow -threads in which -the hollow threads are arranged in s-traigh-t lines, parallel -to each other and a-t distances from each other.
In -fac-t, -this known type of arrangemen-t, which is also conven-tional in metal tubular hea-t exchangers, make the produc-tion of such heat exchangers from hollow -threads di-fficu-lt and expensive. In addition, with this known arrangement of the hollow threads, -the bundles o-f hollow -threads can be damaged, for example nicked, even by minor ex-ternal mechanical inrluences.

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i3~

In order -to increase the heat -transfer capacity of an apparatus according -to the invention, i-t is particlllarly aclvan-tageous~i~ ~the porolls hollow -threads used contain good heat conducting ma-terials such as , :for example metals, and grapl~ te in dust or powder form, whereby these materials can be con-ta-inecl in -the polymers -forming the hol.low -threads and/or can be inser-ted :into -the pores. The pOI'OUS hollow -tllreads can however also contain, in addition for example, f:illers, s.-tabilisers, 1~ addi-tives, carbon black, dye pigments or the like. The external dia~eter o~ the hollow ~threads usecl for the apparatus according to the inven-tion preferably l'ies in the range of f-rom 0.1 to 4 mm. Moreover, the apparatus according to the invention can contain hol:Low threacls produced from two or more components~ o:f which possibly only a proportion is porous.
When using porous hol.low -threads with a small wall tl~ickness, the appara-tu.ses according l;o the i.nvention whi.ch a:re obtained have a large hea-t e~cllange capaci-ty.
Porous hollow threads having a, for example, elipti.cal or triangl~lar, rectangula.r, pentagonal, hexagonal and polygonal cross-section are suitable for -the prodlletion of a hea-t exehanger aceord:i.ng lo -I;he :invent-ion, parti.e-l:la:rly -those hav-ing a rol.lrlcl cross-seet:ion sinee, in appara-tuses with cross:ing po-rous ho'llow threacls aeeord:ing to -the invention proclueed from porous _ 2i --hollow threads having a round cross-section, the -threads contact each other subs-tan-tially only a-t points and, thus, only a minute propor-tion of the en-tire heat exchanger area is los-t through these points oi` contact.
The porolls hollow threads used can also advan-tageously be profiled in-ternally and/or externally.
It is also possible -to firmly join -together two, three or more porous hollow threads lying in a parallel position relative to each other, at their respec-tive contacting surfaces, for example by fusion, welding or adhesion. Porous hollow -threads having a cross-section whlch optionally changes periodically in shape and~or size continuollsly or intermit-ten-tly in -tlleir longitudinal direction are also suitable. Porous holLow threads of this type can advantageously influence -the mode of operation o-f the heat exchanger according to -the invention in various ways. Thus, by means of porous hollow threads which are suitably profiled internally ancl/or externally - it is possible, for example, to increase -the internal ~4~
- ~2 and/or ex-ternal heat exchange surface, to improve the nick-resistance of -the porous hollow threads and/or -to reduce the contact area of t~e crossing porous hollow threads. Moreover, the heat transfer capaclty is fur-ther increased since the heat transm1ssion on the prof`iled surfaces of the porous hollow threads is improved by turbulence in the respective fluid. Apparatuses which are more compact and/or more stable in shape can also be produced in part l`rom porous hollow threads of a non-circular cylindrical shape.
To ensure good conduction of heat through the porous hollow threads, the wall -thereof should be as th1n as possible but should still be sufficiently thick to rneet the mechanical requiremen-ts. Porous hollow threads whose wall thickness ranges from 0.02 -to 0.5 ~m have proven ad~antageous for most purposes. To achieve a good hea-t -transl~ission coefficient (k-n~nber), the cross-sec-tions of the porous hollow threads used should be dimensioned accordingly.
The looped or partially looped arrangemerlt of the porous hollow threads in an apparatus according to the inven-tion is acnieved according to the invention in a simple manner particularly in -that one or more continuous porous hollow threads are wound using a spooling or winding device with one or more thread guides which are Inoved to and fro - 23 ~-parallel -to the ro-tational axis of the spooling device, for example)on a perforated tubular reel holder (also known as bobbin or spool) and, in this way, forln a single or multiple layered spooled or wound melnber.
Tnis arrangement lS particularly advan-tageous since, in the serviceable condition of the apparatus 9 the porous hollow -threads have the shape of a spatially extending coil, the porous hollow threads advantageously being arranged in several layers for achieving an easily penetrable bobbin package which is stable in shape in such a way that the porous hollow threads in each layer contact the porous hollow threads of the adjacen-t layers and cross over optionally several times. This arrangement of the porous hollow threads allows a large heat transfer surface in a small space since, although the porous hollow -threads touch each other at the points of intersection, only an insignificant proportion of the heat transfer surface is lost by this reciprocal contact.
The reel holder accommodating the spooled or wound member need not necessarily have a circular cross-section as its cross-section can also be designed ellip-tical or as a polygon, in particular as a rec-tangle with rounded corners. ~imilarly, the reel holder used for producing the spooled or wound member can also have a cross-section which increases or decreases along i-ts longitudinal axis .

.

5~3 Thus, its surface area can be designed, for example, conical, diabolo-shaped. truncated pyramid shaped with rounded lateral eclges or barrel-sllaped e-tc.~o that the porous hollow t}lread~0und on a reel holder shaped in this way generally form a spooled or wound member whose shape corresponds to the shape of the respective reel holder.
In another embodiment of the apparatus according to the invention~the porou~l ho~low threads hGve -the sn~e o~
a spiral lying in one plane.
The apparatuses according to the invention can however also be produced from one or more sheets which ha~e been produced by a weaving, knitting or ~orl~ing method or a depositing me-thod. Like the spooled or wound members, sheets of this type can also be produced in a rapid and simple manner.
In order to produce apparatuses according to -the invention .from spooled or wound members, the two face ends can be cast on a short portion, measured in the longitudinal direction of the woLmd member, for example in a curable casting composition such as cast resin, polyurethane or the like, the casting composition penetra-ting completely in -the said region of the woLmd member and op-tionally forming one flange-like projection outside each wound member, llavLng a larger circllmferellce -than -the wound member. A
(flange-like) projection of this type can however also be 11L.'~O~33 provided only on one of the two faces of the wound member.
The arc-shaped turned back parts of -the individual layers of the wound member lying at th~ ends of the woSwnd member are removed by carrying off a proportion of each of these (flange-shaped) projections from -the end into the region of the porous hollow threads, and a configuration is produced in -this way~from the original wound members which consists of a plurali-ty of hollow thr eads pieces arranged in several layers in the form of a coil and crossing each other several times, whose openings merge from the casting composition at the external faces, generally running perpendicularly to the longitudinal axis of the wound member, of the remaining ~ part of each of the ~flange-like) projections described above.
To produce apparatuses according to the invention from sheets, one or more edges of the sheets which are optiorally also superimposed can be cast in a suitable manner, for example in cast resin in each case and the openings of the porous hollow threads can then be freed in a similar manner, as already described above for spooled and wound members.
By winding 9 shifting or arranging the porous hollow threads ln ano-ther manner and sOy cutting the bundle of windings in a suitable manner it is possible to produce appara-tuses according -to the invention in which the inlet openings and .~ .

5~3 _ 2~ -the ou-tlet openings of the porous hollow threads lie in one and the same plane~ but are shifted, for example,by 180 each and/or at equal or differing distances from each other ln each case and are thus arranged in such a way that all inlet openings lie in one half of this plane and all outlet openings lie in the other half of this planeO
- It is also possible to produce apparatuses according to -the invention which allow as much fluid as desired to participate in the heat transfer without the individual fluids being mixed together.
The apparatuses according to the in~ention produced from a spooled or wound member can, for example, be equipped in such a way that the inlet openings and the outlet openings for a first fluid lie at one end of the apparatuses and those for a second fluid lie at the other end of the apparatuses.
To produce a plurallty of smaller apparatuses, it is possible to divide the spooled or wound r~embers or sheets intended for the production of the appara-tuses in-to units, for example, strips or cliscs of desired size, in which case the porous hollow -threads are pref`erably fixed in shape and position beforehand in a suitable manner, for example, by casting into cast resin or the like as already described, in those regions in which the division is to -take place, and their openings can thus be freed without dif~iculty by -the division It is also possible within the scope of the present invention to cast the porous ho~low threads into a material which is a good conductor of hea-t in order to transfer heat in this ~anner from one fluid to the said material which is a good conductor of heat o~ vice versa. The apparatuses according to the invention which are designed in this way and which also have, for example, two separa-te circuits for two fluids which are to be kept apart allow heat to be transferred~ for example from the first fluid initially onto the cast me~ber which is a good conductor of heat and thence to deliver it to the second fluid. It is also possible with apparatuses of this type, for example, to deliver the heat absorbed) for example, by radiation, from the cast member which is a good conductor of heat simul-taneously to two fluids Apparatùses according to the invention are suitable for solving even the most demanding problems of heat transfer of the type which can arisej for example during evaporation or condensation. In particular, the apparatuses according to -the invention are suitable wherever there are only relatively small temperature differences for the recovery of energy which inevitably demand large heat transfer surfaces which obviously have to be arranged in the minimum of space. Due to the desirable corrosion properties of the porous hollow threads which can be used for the produc-tion o:f -the heat exchanger according to the invention, -the appara-tuses according to -the :invention..
are particularly sui-tab~e for corrosive media such as fo~ example acicls and caus-tic .solu-tions. By selec-ting sui.-table porous hollow threads to he usedy it is possible, by means o-f the known dif:Eering surface ~roperties -thereof, also -to use -the apparatuses accord:ing -to -the invention -for those fluids which tend to form deposits on the tube walls in conventional metal tubular heat exchangers.
The appartuses according to the invention are-therefore equally suitable :eor chemical processes, in the production or conversion of energy, in re:t`r:igera-t:ion, in air-conditioning, in -the food indus-try, in centrat.
hea-ting, in land, water and air vehicles, in particular as an oil cooler, as a water cooler for discharging enginer heat or for heating -~resh ai:r supplied to -the interior of -the vehicle? as a condenser and as an evaporator, :in particular also as a :rlash evaporator.
The apparatuses, according to -the inven-tion a:re suitable quite speci-fical:ly for heat pump devices in which,for example, heat from the surroundlng air or from -the grollnd is used for heat:ing hous:ing space or as co~Llectors for rece:iving t;he heal; of the.sun, rOr Wtl:i..Ch l)~lrl)OSe those embod:illlents of -the appa:ra-tuses accord:i.ng to the invent:ion in w}ricll -the porous hollow t;hrea.ds are ar:ranged :in only one layer and, more~over, are blacl~, have proven particularly advantageous.

- 2~9 -The apparatllses according -to -the inven-tion are thus suitable for solving mos-t problems oE heat -transfer wi-th op-tionally simultaneous exchange of ma-terial, i.e.
for the hea-t -transEer from gaseous fluids -to gaseous fluids, from liquid -fluids to l:iquid fluids, :Erom l.iquid fluids -to gaseous fluids and vice versa, from soLicls materials to gaseous and/or liquid fluids and vice versa, in which c.ase care has to be -taken to.limit the tempera-tures o:E the materials participating in the hea-t exchange accordingly due to -the physical and chemical properties oE the porous hollow -threads used.
In a~dition to the suitable polymers already proposed and men-tioned, the polyamides, in particular polyhexame-thylene adipic ac:kl amide, the polyes-ters as i5 well as the polyole~ins can also use in embodiment of -the invention.
Due -to their chemical resistances, for example, to food s-tuf:fs and carbon dioxide containing liqu:ids, polyesters, in particular polyethylene tereph-thala-te~
are preferred. I:f chemical resis-tance is desired in addition to good -thermal stability, hollow threads composed o:E polyile:f:ins, in part:i.cular o:E polypropylene, are prefe:rred. I:E higher strengtll vall.les are desired, tlle llollow l]lreads are p:r-oduced :from ~po:lyam.i.des,:in ~5 pa:rticular :Erom po.lyhesamethylene adipic acid amide.
When d:imensionin~ the appa-ratllses accord:in~ to -the _ 3~) -invention, it should be noted that the heat trans~er surface attainable per uni-t volume available is grea-ter, the smaller the diameter of the porous hollow threads to be used. The amo-mt of heat to be transferred generally increases as the diameter of the hollow threads decreases if the cross-section of flow o~ all porous hollow threads and the quantity of fluid rèmain constant. It should however be noted that the pressure loss in -the porous ho~ow threads also increases in this case. It should also be noted that the nick-resistance of -the porous hollow th~ ads generally decreases as the diameter increases and the wall thickness stays constant. With a suitable choice and dimensioning of the porous hollow threads used for the apparatuses according to the invention, i-t is possible -to achieve specific heat transfer capacities which can be better, and in part even considerably better than those which can be achieved with conventional metal tubular hea-t exchangers.
The choice of suitable porous hollow threads should be made as far as possible in such a way -that the heat transmission resistance through the wall o~ the porous hollow threads is subs-tantially negligible relative to the heat transfer resis-tances occurring inside and outside the porous hollow threads. This means tha-t ~orous hollow threads made of a material having rela-tively good proper-ties f thermal conductivity should have thicker walls than -those ~ .

with very low thermal conductivi-ty values.
A "hollow thread" in the con-tex-t of the present invention is a hollow cylindrical configuration of any length having a, for example, circular or elliptical cross-section with a wall thickness which is generally subs-tantially constant in the longltudinal and circum~erential direc-tion.
The term"cross-section"of the porous hollow threads the spooled or wound member or the reel holder is interpreted in the context of the invention as the cross-sectional area obtained if a porous hollow thread, a spooled or wound body or a reel holder is cut at a random point or at a point described in more de-tail3perpendicularly to its longitudinal or ro-tational axis. In the case of a round porous hollow thread, a circular cross-section is ob-tained in this way.
In the case, for example, of a spooled or wound member which is wound on a reel holder having a rectangular cross-section with rounded corners, a rectangular annular cross-section with ro~nded corners is obtained according to -this defin:ition.
The term~loop form~in the context of the present invention is interpre-ted as -that form which differs from a rectilinear form and, in particular, that type of flat or three-dimensional curvature in which the radius of curvature is sufficiently large to preven-t nicking of the porous hollow threads. The radius of curvature is generally smaller than 1 m but it can also be larger. Il;

the objec-t forming -the basis of the present invention, it is not necessary for all porous hollow threads to ha~e a loop form over their entire lengt~l but rather it is sufficien-t for the majority of the porous h~llow threads to have a loop form i.e. for each individual porous hollow thread in an apparatus according to.the invention to have a loop form over ~ majority of its length and/or for rectilinear and loop-form porous hollow threads to be present providing the total length of all.the porous hollow threads and/or hollow thread portion present in loop form is greater than the.
~otal length of all rectilinear porous hpllow threads and/or hollow threadPortions~
This loop form of the porous hollow threads allows the porous hollow threads to cross over",optionally several times at substantially short intervals,and to support each other in this way so that each porous hollow thread is generally unsupported only over relatively short portions of i~.s length so that the risk of the porous hollow threads being nicked is reduced considerably.
Al-though the above-mentioned advantages are generally obtained only by the arrangement according to the invention of the porous hollow threads in apparatuses in which heat is transferred, it is nonetheless t)a~,i.c~ll.y possible also to arrange -the porous hollow threads in a known manner, thus, for example, in a U-shape or in the form of a bundle of straight porous hollow threads and the like arranged parallel to each other and a-t distances from each other.
Serviceable appara~uses which possibly yield satisfac-tory to advantageous results can also be produced using porous hollow threads other -than -those according to t}le second aspect 5 of the inventi on and tho~:e already propo~3ed .
Finally, i-t is possible accordlng to the inven-tion and in many cases advan-tageous to use those porous hollow threads for the production of apparatuses according to the invention in which, in addition to the heat transfer and/or the vaporisation .of a proportion of the liquid flowing throu~h the porous hollow threads on the external surface of the porous hol].ow threads, filtration, microfiltration, transfer of material - . or exchange of ~aterial takes place as proposed. Those porous hollow threads which contain no layer ac-tin~ as a nlembrane wll:icll is optionally impermeable to fluid and thus have an operl pored surface,are generally particularly suitable for this purpose.
Moreover, it is advantageous in many cases for these, but also other9 applicatibns to use those hollow threads which have an open pored surface only in portions and have the membrane-like layer described in more detail above on the remaining portions. The optionally un.interrupted membrane-like layer can be arranged on the external and/or internal surface of the porous hollow threads. This layer is particularly preferably provlded after pr~duction of the spooled or wo~d member, in particular inside the porous hollow . .

5~

-threacl s .
Finally, i-t is poss:ible according to the invention also to use the apparatuses according to the inven-tion with heat exchangers of the -type which frequen-tly oceur cluring, for example, m:i.x:ing dissolution, dill~-tion or chemical reae-tion, et¢., of several reactan-ts, a proportion of a fluid reaetan-t flowing through -the hollow threads being allowed to issue th:rough -the pores of the hollow -threads and enter a second -fluid reaetan-t, for example.
As the porous hollow threads described herein ha~ve proven most sui-table not only -.in the appara-tlls according to -the invention, the scope ol the :invention also cove~rs -the porolls hollow -threads proposed, -the holl~ th:reads comprising the propert~.es according -to -the invention individually or i.n any comb:ination.
The invention will now be deseribed :in more de-tail with reference to the drawings.
Figures i -to 7 show cross-sections -through porous hollow threads of various shapes.
Figures 8 and 9 show longitudinal sec-tions througll porous llollow threacls wh-.ich are no-t designed as eireular ey}inders.
Figures 10 and ll show a simpliIiecl schematic view o-f the produc-t:ion of a multi-layer wol~nd member from a porous hollow thread.

S3~

Figure 12 shows a simplified schema-tic view of a longitudinal sec-tion through a spooled member of porous hollow threads with flange-like projec-tions at its ends cast from a casting composition.
Figures 13 to 15 show a simplified schematic view of longitudinal sections through spooled members of various shapes composed of porous ho~ow -threads wlth flange-like projec-tions cast at -t:heir en~s erom a casting composi-tion.
Figure 16 shows a simplified ~iew of a spooled member from porous hollow threads with only one flange-like projection made of a casting composition arranged at its end.
Figure 17 shows a simplified schematic view of a spooled member with flange-like projections cast at bo-th i-ts ends from a cas-t-ing composi tion.
15- Figures 18 to 21 show a simplified schematic view of embodiments of apparatuses according to the invention using a spooled member made of porous hollow threads.
Figures 22 to 24 show a simplified schematic view of the production of a spooled member made of two porous hollow threads.
~igure 25 shows a simplified schematic view of an embodiment of an apparatus according to the invention using a spooled member produced according to Figures 22 to 24.
Figures 26 to 31 show a simplified schematic view ~ ' .... . . . ., , . . . . .. . . _ ..... _.. _. _.. ... .. _ .. _ _ .. _ .... .

i33 of various embodiments of bundles of hollow threads produced ' from spooled members each having differing cross-sectional shapes.
~ Figures 32 to 37 show a ,simplified schematic view of the production of a~ embodiment of the apparatuses according to the invention from a substan-tially disc~shaped wound member fro~ porous hollow threads.
Figures 1 to 5 show possible cross-sec-tions of ;' profiled porous hollow threads of the type which are sui-table for apparatuses according to the inventi,on.
' In the form illustrated in Figure 1, the porous hollow thread has a substantially circular cylindrical cavity 27 while it has a rib-like elevation 26 running ' in its longitudinal direction on its exterior, which can 15' optionally consist of a different material from the hollow thread sheath.
The porous hollow threadillustrated in Figure 2 also has a sùbsta~tially circular cylindrical cavity 27 and four rib-like elevatlons 26 running in its longitudinal direction, optionally made of a differing material.
The porous holl'ow thread illustrated in Figure 3 has a substantially three-tabbed cross-section, the cavity 27 having a similar shape to the hollow thread sheath 28 so that this porous hollow thread has a wall of substantially constant thlckness over its circ~nference.
.

' ~ - . .
.
~ ' - 37 ~

The porous hollow thread illustrated in Figure 4 has an externally substantially circular sheath 28 which has on its interior four rib,like elevations 26 running in the longitudinal direction of the porous hollow thread and penetrating into its cavity 27 which are optionally made of a differing material from the sheath 29.
Figure 5 shows a porous hollow thread in which the sheath 28 has a hexagonal annular cross-section and the cavity 27 has a hexagonal cross-section.
Figure 6 shows a cross-section through a hollow thread configuration which can be produced, for example, by fusing three porous hollow tllreads of round cross-section together on their common lines of contact.
Figure 7 shows a cross-section through a porous hollow thread with a cross member 29 arranged centrally inside the porous hollow thread and running in its longitudinal direction. This porous hollow thread therefore has two equally large cavities 27 which are sep~rated from each other by the cross member 29 and run parallel to each other and have a semi circular cross-section.
Figure 8 shows a longitudinal section through a porous ho]low thread having an external diameter or circumference which increases and then decreases again at optionally regul æ
intervals in its longitudinal direction and having an internal dian~ter or cavity circum~erence which decreases and then 31 :i L L'~J~O S3~3 increases again at optionally regular intervals in its longitudinal direc-tion. The porous hollow thread thus has a sheath 28 whose wall thickness changes in the longitudinal direction of -the porous hollow -thread.
5- ~ Figure 9 shows a longitudinal sec-tion through a porous hollow thread with a cross-section which increases at-optionally regular intervals in its longitudinal direction, the wall thickness of the porous hollow -thread remaining : ;~ cunstant in its longitudinal direction.
~'igures 10 and 11 show a simplified sche~tic view .`. of a known device for the pr.oduction of spooled members which are suitable for apparatuses according to the invention.
A continuous porous hollow thread 1 supplied is wound by means of a thread guide 2 which moves to and fro onto a rotating perforated re~l holder 3 so tha-t a spooled member 4 is produced which is made up in the manner of a coil of several layers or portions bf the con-tinuously supplied and wound porous hollow thread 1 which cross over at a predetermined angle.
Figure 12 shows a longitudinal section through a spooled me~ber 4 which is producea usi.ngJ'i~or example, a device described with reference to Figures 10 and 11.
The spooled member 4 is provided at its two ends 5 with flange-like projectlons 7 made of a curable casting composition which has been brought in-to the desired shape by centrifu~al c~s-ting. The openings of the porous hollow -threads of the ,~, .

~ 3 spooled.member 4 can be freed by severing a part of the flange-like projections 7 along the lines A and B. The perforated reel holder 3 ensures that the spooled mer~ber 4 ~ is traversed radially.
5r The spooled member 4 illustra-ted in a longitudinal section in Figure 13 is forrned by the uniforln winding of a con-t,inuous porous hollow thread on a conically designed reel holder 3 and thus has a conical shape i-tself, ~i-th this spooled ~ember 4, the ends of -the individual tube portions are freed by severing a propor-tion of -the flange-like projections 7 (as already desc.ribed with'reference to Figure 12).
The spooled member 4 illustra-ted in the lon~itudinal , section in ~'igure 14 is produced by -the uniform winding of a continuous porous hollow thread on a diabolo-shaped reel holder 3 and therefore has a diabolo shape itself. In this : spooled member 4, the ends of the indi~idual hollow thread portions a~ already freed by severing a part of the flange-~, like projections 7 (as already déscribed with reference to 2Q ~igure i2~ ' The spooled mernber 4 illus-tra-ted in -the longitudinal sec-tion in Figure 15 is produced by the unifor~ winding of a continuous porous hollow thread-onto a barrel-shaped reel holder 3 and is thus barrel-shaped itself. ~i-th this' spooled rnember 4, the ends of the indiv.idual tube por-tions are freed by severing a par-t of the flange-like projections s~

7 (as already described with reference to Figure 12).
The spooled member 4 illustrated in Figure 16 is produced by the ~liform winding of a continuous porous hollow thread on a circular cylindrical reel holder and thus has a circular cylindrical shape itself. This spooled member 4 is provided wi-th a flange-like projec-tion 7 only at one end so that the ends of the individual hollow thread portions of the spooled member 4 are freed only on this one side by the severing of part of the flange-like projection 7 already described.
The path of flow of a fluid through the porous hollow threads of a spooled member of this type runs in the manner ~ of that of a U-shaped pipe. This means that the inlet and outlet openings for th~ fluid lie in one and the same plane in -this spooled member.
Figure 17 shows a spooled member of the type produced when the flange-like projections 7 are partially severed, for example in the manner shown in Figure 12 along the lines-A~A and B-B.
Figure 18 shows the use of a spooled member 4 produced in the manner described with reference to Figures 10 to 12 in an apparatus according to -the invention. The spooled member 4 with -the flange-like projec-tions 7 is arranged in the correspondingly dimensioned housing 10 in this case. A
first fluid 8 flows through the inlet nozzle 11 into the "~
i33 ), ,l distribuion c.hamber 16 of the apparatus and passes thence into the inlet openings of the porous hollow threads arranged in the spooled member 4, flow's through them and leaves them at the opposite end of the spooled member 4, passes into the collecting chamber 17 of the hea-t exchanger and leaves it through the outlet nozzle I2. It can also flow through the.porous hollow threads in the opposite direction. A second fluid 9 flows through the inlet nozzle 13 into -the core chamber 18 of the spooled member 4 which is sealed at its end 15, flows through the spooled mem'ber 4 in the radial direction from the in-terior outwards and passes into -the annular cylindrical collection chamber 19~ whence it leaves the apparatus ~ through the outlet nozzle 14.
As in,the embodiments of the apparatus according to .15 the inventlon described in Fi~ures 19 to 21 and 34 to 37, , , the first fluid 8 can be~a liquid and the second fluid 9, ' for example, a gas or air~ which absorb and entrain the liquid vapours produced on -the external surface of the hollow thread . portions when employing evaporation or vaporisation cooling.
The first fluid 8 can have a hgher or lower -temperature than the second fluid 9. However, if it is undesirable for the fluids to flow through the wall of -the porous hollow threads the apparatuses can be produced according to the invention from porous hollow threads surrounded by a membrane-like layer which is impermeable to fluid.

- ~

- ~2 - ~ ~4~3 Figure 19 shows an apparatus of the invention in which spooled member 4 includes a dividing wall 21, which is so arranged, that the free flowing cross-section of the individual porous hollow threads is not interrup-ted. A first Eluid 8 flows through the apparatus in the same manner as already described with reference to Figure 18. A second fluid 9 flows through inlet noz~le 13 of the apparatus, into the annular cylindrical distri-bution cham~er 20, flows then in the right-hand halE of spooled member 4 from the exterior inwards in a radial direction, and enters the core space 1~ of spooled member 4 which is sealed at the end 15. Subsequently the second fluid 9 flows in the left-hand hal~ of spooled member 4 from the interior outwards in a radial direction, and passes into the annular cylindrical collection chamber 19, whence it leaves the apparatus through the outlet nozzle 14.
Figure 20 shows an ap~aratus of the invention in which the porous hollow threads of the spooled member

4, according to Figure 16 are included, the spooled member 4 having a flange-like projection 7 only at one end, and severed as described. The inlet openings and the outlet openings of the porous hollow threads are displaced 180to each other, and are therefore opposed, that is they are similarly arranged, as in the conventional heat exchanges with U-shaped tubes. In this apparatus a first fluid 8 enters through ii33 the inle-t nozzle 11 lnto the distribution chamber 16, passes thence in-to the interior of the porous hollow threads of the spooled member 49 traverses it firstly in one direction and then in the substan-tially opposite dlrection and subsequently

-5 enters the collection chamber 17 whence it leaves the apparatus again through the outlet nozzle 12. A second fluid 9 flows through the inlet nozzle 13 into the annular cylindrical distribution chamber 20, whènce it flows through the spooled member 4 from the exterior inwards in a radial direction and enters the core space 18 of the spooled member 4 which is . sealed at the end 15 and thence leaves the apparatus -through the outlet nozzle 14.
Figure 21 shows an apparatus according to the invention which combines the essential features of the spooled member 4 shown in Figures 19 and 20. In this case, the first fluid 8 flows through the porous hollow threads of the spooled member 4 in the manner described with reference to Figure 20 and the second fluid 9 flows round the porous hollow threads of the spooled member 4 in the manner described with reference to Figure 19.
~ `igures 22 to 23~ show a simplified schema-tic view of a device for the production of a spooled member 4 from two porous hollow threads 1 which are supplied separately from two spiols 6 but are wound simultaneously onto a common reel holder 3. By arranging -the thread guides 2 offset in the longitudinal direc-tion of the spooled member 4 in the .. ~ .
.. .. . .. , . .. . , . _ ___ _ , s~

manner shown in Egures 2~ and 24, i-t is possible to produce a spooled member 4 in which the respecti~e layers of the two porous hollow threads 1 a~ wound offset relative to each other in the longitudinal direc-tion of -the spooled member 4 so as to form a region 22 at each of the ends of the spooled ~ember 4 which is formed only by one of -the two porous ho~ow threads. A spooled member which has -the inlet and -the outlet openings for a first fluid on one side and those for a second fluid at the opposite end is produced by removing these two regions 22.
The use of a spooled member produced in this way in accordance wi-th Figures 22 to 24 in an appara-tus according - to the inven-tion is illustrated in Figure 25. In addition, the spooled member 4 is located in a solid or liqu.id substance 23 which is a good conduc-tor of heat in this embodiment illus-trated in Figure 25. An apparatus of this type allows, for example, the heat to be -transferred from a first fluid 8 to a second fluid 9 u-tilising the good heat conducting properties of the substance 23, the fluid 8 flowing through the corresponding layers of the spooled member formed by a porous hollow thread~ for example in the manner illustrated in Figure 20. In Figure 25, -thls path of flow is indicated schema-tically as a broken line, while the second fluid 9 follows a path of flow which is a mirror image of it, which is- indicated by the continuous line in Figure 25.

~ .

~L ~ Lq~ 5j33 - ~5 ~ igure 26 shows a spooled member 4 with flange-like projections 7 arranged at its -two ends, the flange-llke projections 7 ~like those of the spooled member 4 illustrated in Figures 12 to 21) having a larger external circumference than the spooled member 4. The flange~like projections 7 and the spooled member 49 however, have an elliptical annular cross-section in this case.
Figure 27 shows that a spooled member 4 can be cast not only at its ends and cut up accordingly in the manner described above but can also be cast along one or more of its generating lines. In the embodiment illustrated in Figure 27 the porous hollow -threads consequently merge into two circular cylindrical cavities 24 and 25 which are surrounded by a wall consisting, for example, of cast resin which, as explained with reference to the Figures already.~escribed, act as distribution and collection chamber for the fluid ~lowing through the porous hollow threads.
Figure 28 shows a cross-sçction through a spooled member 4 which is obtained if porous hollow threads are wound on a reel holder 3 witll a rectangular cross-section having rounded corners.
Figure 29 shows a cross-section through a spooled member 4 which is obtained if a spooled member L according to Figure 28 is cast, for example in cast resln, along two of its generating linesin the manner described with reference - ~16 ~-to Figure 27 and the openings of the porous hollow threads are then freed in the manner already described.
Figure 30 shows a cr~s-section through a spooled member 4 which can also be produced from -the spooled member 4 illustrated in Figure 28, and Figure 31 shows one which is obtained in a manner similar to tha-t described in Figure 27 from a spooled member 4 of circular annular cross-section7 The embodimen-ts according to the inven-tion illustrated - in Figures 27 to 31 are eminently suitable for the heat transfer from a liquid medium to a gaseous medium (for example as a car radiator) or vlce ~ersa~ the liquid medium preferably flowing through the porous hollow threads and the gaseous medium flowing round the porous hollow threads, whereby vaporization cooling can be employed or not employed, depending on the type of porous hollow threads used, as described aboYe .
Figure 32 shows a cross-section through an annular coil holder 31 of the type which is sui-table for the production of a disc-shaped coiled member from porous hollow threads.
F`igure 33 shows a possible arran~ement of the individual thread por-tions, for example of a cont.inuously wound porous hollow thread on the annular coil holder 31.
In -this case, the hollow thread portions can be arranged in several superimposed layers which each cross each o-ther several times. By cas-ting -the external portion of the annular ~ 47 -coil holder 31 for example into a curable casting ccmposition and then removing a part of the annular casting composition projection into the region of the turned ~ack fragments 32 of the hollow thread portions, the porous hollow thread 1 which is initially continuous is divided into a plurality of equally long hollow thread portions arranged in several layers and crossing over each other several t~mes and the openings in the individual hollow thread portions are freed at each severing point.
The external diameter of the unw3rked part of the annular casting canFosition projection is thus generally equal to or slightly smaller than ~le external diameter of the annular coil holder 31.
Figure 34 shows a sectional illustration along the line XXXV-XXXV in Figure 33 of a disc-shaped embodiment of the apparatus according to the invention in ~hich â wound member 4 according to Figure 33 has b~en used. By s~itably arranging the inlet nozzle 11 and the distribution chambers 16 as well as the collection chamb~rs 17 and the outlet nozzle 12 for a first fluid 8 and the inlet nozzle 13 and the ~0 distribution chambers 20 as w211 as the oollection chambers 19 and the outlet ~ozzle 14 for a second fluid 9, an apparatus having a total of two inlets and tw~ outlets for each of the tw~ fluids 8 and 9 is obtained. In this case, the fluid stream entering the apparatus through the inlet at anyti~e is divided so that only half o~ each partial stream of fluids 8 and 9 reaches the two outlets communicating with the 3~ 3~

_ ~8 corresponding inlet at any time and combines there wi-th one of the halves of -the other partial stream of fluids 8 and 9. Figure 34 shows -this path of flow by arrows and four hollow threa~ portions dra~n as thick lines.
Figure ~5 shows a cross-section along the line XXXV-XXXV through Figure 34. The annular coil holder 31, the annular projection 7 made of a curable casting composi-tion, the wound member 4 as well as the -two opposirlg distribution chambers 16 for the first fluid 8 can be seen.
Figure 36 shows another possible arrangement of a continuous porous hollow thread 1 on an annular coil holder 31 for the production of a hollow thread winding for disc-shaped embodiments of the ~ppa:ra-tus according -to the invention~ .
Figure 37 shows a cross-section through an apparatus according to the inven-tion in which a wound member according to Figure 36 has been used. The openings in the individual hollow thread layers have been freed here, as already described with reference to Figures 32 to ~5. In this embodiment, the first fluid 8 flows through the inlet nozzle 11 into the distribution chamber 16, then traverses the porous hollow threads of the wound member 4, enters the collection chamber 17 and leaves the apparatus through the ou-tlet nozzle 120 The reference numerals of the remaining parts of this appara-tus correspond to the parts described -- ~1(") --by way of example with reference to Figure 34. An exemplary second fluid participating in the hea-t transfer traverses the apparatus illustrated in Figure 37 in substantially -the axial direction thereof.
~hereas the apparatus illustrated in Figure 37 is tllus suitable for transferring heat, from one medium to another~
a to-tal of -three mcdia can participate in -the heat transfer in the apparatus illustra-ted in Figures 34 and 35v With the apparatus illustrated in Figures 34 and 35, the third medium could be~ for example, a solid or liquid ,s,ubstance which is a good conductor of heat and which surrounds the porous hollow threads from the ou-tside or a third fluid which flows through the heat exchanger in i-ts axial direction.
The use of the disc-shaped wound member described by way of example with reference to Figures 33 and 36 is not restricted -to the production of substan-tially dlsc-shaped apparatuses bu-t rather it is ~ossible according to the invention to superimpose a plurality of these wound members and, in this way, to allow an op-tional number of fluids to participate in the transfer of materials and/or heat.

Claims

The embodiment of the invention in which an exclusive property or privelege is claimed are defined as follows:

1. An apparatus for transferring heat comprising hollow threads composed of synthetic polymers having from 10 to 90% by volume of inter-communicating pores and an even surface containing open pores, the propor-tion of the surface which is open amounting to from 10 to 90%.

2. An apparatus according to Claim 1, wherein a majority of the individual hollow threads are arranged in the form of regular and/or irregular loops over a majority of their respective lengths.

3, An apparatus according to Claim 1, wherein all of the hollow threads are arranged in the form of regular and/or irregular loops over their respective lengths.

4. An apparatus according to any of Claims 1,2 or 3, wherein the hollow threads are arranged in the form of regular and/or irregular loops over the entirety of their respective lengths.

5. An apparatus according to Claim 1, wherein the hollow threads are arranged in the form of a spatially extending coil and/or a spiral lying in one plane.

6. An apparatus according to Claim 1, wherein the hollow threads are arranged in several layers.

7. An apparatus according to Claim 6, wherein the hollow threads in each layer cross over the hollow threads in each of the adjacent layers several times.

8. An apparatus according to Claim 1 comprising a multi-layer spooled or wound member.

9. An apparatus according to Claim 1 or 8 comprising a spooled or wound member having a round, elliptical or polygonal annular cross-section with rounded corners.

10. An apparatus according to Claim 1 or 8 comprising a spooled or wound member having a rectangular annular cross-section with rounded corners.

11. An apparatus according to Claim 1 or 8 comprising a spooled or wound member with an annular cross-section which increases and/or decreases along its longitudinal axis.

12. An apparatus according to Claim 1 or 8 comprising a woven, worked or knitted sheet or a sheet produced by a depositing method.

13. An apparatus according to Claim 1 further comprising at least one inlet each and at least one outlet each for at least three fluids participating in the heat transfer.

14. An apparatus according to Claim 1, wherein a pro-portion of the liquid flowing through the hollow threads passes outwards through the pores and vaporises or evaporates on the outer surface of the hollow threads.

15. An apparatus according to claim 1 or 14, wherein in addition to the heat transfer, filtration, microfiltration, separation of material or exchange of material takes place through the porous hollow threads and/or simultaneous vaporisation or evaporation of the proportion of the liquid flowing through the porous hollow threads takes place on the outer surface of the porous hollow threads.

16. An apparatus for transferring heat comprising hollow threads composed of synthetic polymers having from 10 to 90% by volume of inter-communicating pores and an even surface containing open pores, the proportion of the surface which is open amounting to from 10 to 90%, wherein a layer which acts as a membrane is applied to the hollow threads and/or the hollow threads contain graphite, metal particles, fillers, stabilisers, additives, carbon black or dye pigments or any com-bination thereof and/or the hollow threads have a substantially circular cross-section with an external diameter falling within the range of 0.1 to 4 mm and/or the hollow threads have a wall thickness falling in the range of from 20 to 500 um and/or the hollow threads are internally and/or externally profiled and/or the hollow threads have a cross-section which changes con-tinuously or intermittently, in shape and/or size in its longitudinal direction and/or the hollow threads consist of two or more components and/or in that only a proportion of the components is porous.

17. An apparatus according to claim 16, wherein said layer which acts as a membrane is impermeable to fluid.

18. An apparatus according to claim 16 or 17, wherein the hollows have a cross-section which changes periodically continuously or intermittently.

19. A device for the transfer of heat by synthetic polymer hollow filaments with 10 to 90 per-cent by volume of pores in mutual communication, said filaments having a flat surface with open pores the apertures of which constituting 10 to 90 percent of the surface, including means associating with said filaments for connection thereamongst.

20. In a heat exchanger comprising a plurality of porous hollow filaments, the improvement wherein said filaments are of a synthetic polymer effective for heat transfer by thermal conductivity with 10 to 90 percent by volume of pores in mutual communication, said filaments having a flat surface with open pores the apertures of which constitute 10 to 90 percent of the surface, said pores being such that a portion of liquid flowing through the hollow filaments is able to pass outwardly through the pores and vaporize or evaporate on the outer surface of the filaments to further cool the flowing liquid.

21. A heat exchanger according to claim 20, wherein a layer which acts as a membrane is applied to the hollow threads and/or the hollow threads contain graphite, metal particles, fillers, stabilisers, additives, carbon black or dye pigments or any combination thereof and/or the hollow threads have a substantially circular cross-section with an external diameter falling within the range of 0.1 to 4 mm and/or the hollow threads have a wall thick-ness falling in the range of from 20 to 500 um and/or the hollow threads are internally and/or externally pro-filed and/or the hollow threads have a cross-section which changes continuously or intermittently, in shape and/or size in its longitudinal direction and/or the hollow threads consist of two or more components and/or in that only a proportion of the components is porous.

22. In a method of exchanging heat in which a flow-ing liquid is cooled by transfer of heat, the improvement wherein said liquid is flowed through porous hollow fila-ments of a synthetic polymer, with 10 to 90 percent by volume of pores in mutual communication, said filaments having a flat surface with open pores the apertures of which constitute 10 to 90 percent of the surface.

23. A method according to claim 22, wherein said synthetic polymer filaments are effective to provide heat transfer from said flowing liquid by thermal conductivity.

24. A method according to claim 22 or 23, wherein a portion of the liquid flowing through the hollow filaments is allowed to pass outwardly through the pores and vaporise or evaporate on the outer surface of the filaments to further cool the flowing liquid.