CA1119159A - Tube-and-plate heat exchanger - Google Patents
Tube-and-plate heat exchangerInfo
- Publication number
- CA1119159A CA1119159A CA000336275A CA336275A CA1119159A CA 1119159 A CA1119159 A CA 1119159A CA 000336275 A CA000336275 A CA 000336275A CA 336275 A CA336275 A CA 336275A CA 1119159 A CA1119159 A CA 1119159A
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- plates
- heat exchanger
- depressions
- projections
- heat
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Abstract
ABSTRACT OF THE DISCLOSURE
A tube-and-plate heat exchanger comprises a plura-lity of plain tubes intended for one of the heat carriers to pass therethrough, which tubes are arranged in paral-lel rows and are received in broachod holes of cooled plates. In cross section the plates are pro-filed so as to form, in the flow direction of another, for example, gaseous heat carrier, continuous symmetric wave line, thereby forming a passage of undulatory shape for the gaseous heat carrier to flow therethrough. Projections and depressions of one plate face respective projections and depressions of another adjacent plate, thereby for-ming continuously alternating divering-converging sections of passages. The projections and depressions of the cooled plates mate with rectilinear sections which have the same angle of inclination to the axis of symmetry of the cross-sectional wave line, ranging from 8 to 45 deg.
The bending radius at the mating place of projections and depressions is not more than twenty times the thick-ness of the cooled plate material. To ensure good ther-mal contact between the plain tubes and the cooled plates, which is obtained by sintering, edges of the broached holes are formed throughout their surfaces around the periphery of each tube. The heat exchanger of the in-vention, intended for use as a water-air cooler, is smal-ler m size and weight, being, all other conditions equal, highly resistant to contamination, preventing air-suspended particles of dust and dirt from penetrating to the air space thereof.
A tube-and-plate heat exchanger comprises a plura-lity of plain tubes intended for one of the heat carriers to pass therethrough, which tubes are arranged in paral-lel rows and are received in broachod holes of cooled plates. In cross section the plates are pro-filed so as to form, in the flow direction of another, for example, gaseous heat carrier, continuous symmetric wave line, thereby forming a passage of undulatory shape for the gaseous heat carrier to flow therethrough. Projections and depressions of one plate face respective projections and depressions of another adjacent plate, thereby for-ming continuously alternating divering-converging sections of passages. The projections and depressions of the cooled plates mate with rectilinear sections which have the same angle of inclination to the axis of symmetry of the cross-sectional wave line, ranging from 8 to 45 deg.
The bending radius at the mating place of projections and depressions is not more than twenty times the thick-ness of the cooled plate material. To ensure good ther-mal contact between the plain tubes and the cooled plates, which is obtained by sintering, edges of the broached holes are formed throughout their surfaces around the periphery of each tube. The heat exchanger of the in-vention, intended for use as a water-air cooler, is smal-ler m size and weight, being, all other conditions equal, highly resistant to contamination, preventing air-suspended particles of dust and dirt from penetrating to the air space thereof.
Description
.9~59 TUB¢-A-~D-PLATE ~[EAT EXCHANGER
The present invention relates to heat engineerin~, and more particularly, to a tube-and-plate heat excnarger, ; This invention can find utility in the manufacture of air-to-air heat exchangers, and liquid-to-air `neat exchangers intended ~or various applications in the constructions o~ air coolers and evaporators required for condensation and evaporation o~ various liquids, This type of heat exchanger is well adapted to operate on both conta,minated and uncontaminated air, The heat exchanger construction o~ t'ne inven~io-n is mo~t advantageous for use as water-to-air and oil-to-air cooler3 incorporated in cooling systems of both movable and stationary power plants.
There is known a tube-and-plate heat exchanger used in the constructions of water-to-air coolers installed in motor vehicles, tractors and diesel locomotives, This type of heat exchanger comprises a plurality of plain and round tubes for the passage of a cooled workint fluid, These tubes are received ln respective through hole~ formed in flat cooled plates, The tubes for the `~
passage of a worlcing fluid can be arranged either in parallel rows or in staggered manner, Thus, t'ne coolers of this type are constructed so as to permit plain rectangular passages or channels to be ~ormed in the ,' ' ' ~
. .
. ~
.. ~ , ' .
~ . . , - .
~.~ l9~S9 intertubular space thereof. These channels or passages are not provided with vortex generators required to intenesify the heat exchanging process in the intertubular space. This intensification of the heat exchanging pro-cess is necessitated by that water-to-air coolers of various power plants operate under conditions where t'ne over-all heat trasfer coefficient K of the cooler is approximately equal to the air heat emission coeffi-cient ~ , i.e. K~ . Therefore, a reduction in size and weight of the water-to-air calls for the increase in K, which is single-valued as ~1. The value of d~is ~nown to be the smallest in plain passages. Therefore 9 the prior-art tube-and-plate heat exchanger is large in size and weight.
The tube-and-plate heat exchangers of the aforedes-cribed construction can be reduced in size and vreight only by way of increasing the hea,t emlssion coeffi~ient oL~
which is possible to carry out by producing the air flow turbulence in the cooler passages with the aid of various vortex generating means.
There is also known in the art a tube-and-plate heat exchanger which comprises plain tubes for the passage of cooled water, the tubes being arranged either in parallel rows or in staggered fashion. In order to intensify the procees of convective heat exchenge in the intertubuler , :
' 1119~59 ~ . ~
space, the cooled plates are profiled, in thc travelling direction of air flow, so as to ~orrn a continucus symmetric wave line, with the cooled plates being arranged in the cooler tube bundle so that projections and depres-sions of each pair of the adjacent plates are equidistant ~rom one another. As a result, there are formed, in the interspace between the adjacent cooled plates, passages for cooling air, which have undulatory shape if viewed in the travelling direction o~ the air flow.
The Xnown water-to-air coolers have been -tested to show insufficient~y high thermohydraulic effectiveness.
The reason for this lies in that the increase in the heat emission coe~-ficient ~lis lagging in such passages very much behind that of the energy input required for stepping up the process of heat transfer as compared with smooth passages. This can be exp~ained by that vortices, formed by a flow of air behind and before each turn in such passages, are equal to, or commensurate with, the height of projection of the waving passage. It should be added that the height of the projection in these types of passages is equal to, or commensurate with, the hyd-raulic passage diameter. As a result, the amount of ener-gy delivored to the cooled air in waving passages is lost (by 70 to 80%) to effect transition to turbulence in the core of the flow wnere the temperature field gradient and that of the heat flow den~ity are smell , ........................................................................ .
; ' . , .
. : ' : ."
.
~119~59 enou~h to bring about æny substantial increase in the heat flow density. Since these large-scale vortices pos-sess con~iderable kinetic energy, they,on overcoming the forces o~ ~iscosity and friction, are gradually disso-ciating to be therea~ter displaced to the wall layer of air. This results in that the wall layer is made turbu-lent, with the turbulence heat conduction and the heat flow density increasing therein. Therefore, the heat exchange process in the waving passage is intensi~ied ;~ by the turbulence of the wall layer of the air flow and not in itis core, though the loss o~ additional energy fed to the air flow in the waving passage so as to induce turbulence in the core of the flow is much greater than that required to produce turbulence in the wall layer : thereof, And this is the main reason for low thermohydra- -ulic e~ectiveness of the heat exchanging sur~ace of the ; prior-art tube-and-plate heat exchanger.
A,'~ An object o~ the present invention is to provide a tube-and-plate heat exchanger o~ the type to permit thermohydraulic effectiveness to be enhanced by inten-sifying convective heat exchange in the intertubular ~pace thereof~
,~ ~nother object of the invention i9 to provide a tube-and-plate heat exchanger which will be smaller in ~ize and weight.
,'; ' ;, . .
, ....
''. ', ~ ; ~` ~ ' . .
lll91S9 Still another o~ject of the invention is to provide a tube-and-plate heat exchanger which i5 well adapted to operate on contaminated cooled air.
Accordingly, the present ïnvention provides a tube-and-plate heat exchanger comprising: a stack of plates spaced with a gap from one another; each of said gaps serving as a - passage; broached holes formed in each of the plates of the stack with the holes of the different plates being in register with each - other; a bundle of tubes corresponding in number to the said holes of each plate, each tube passing through each set of aligned holes; two heat carriers having different temperatures, with heat exchange takins place therebetween, one of said heat carriers flowing through said tubes, the other one flowing through said passages; each of said plates being profiled in s the flow direction of the said second mentioned heat carrier as a continuous wave line with alternating projections and depressions; diverging and converging sections of said pas~ages formed by said projections and depressions of each of said plates being disposed so as to face the respective projections and depressions of one of said plates adjacent therewith; said diverging sections defining a flaring angle; said flaring angle exceeding the critical angle of primary loss of hydrodynamic stability of laminar structure of the flow of said second mentioned heat carrier.
Projections and depressions of the cooled plates are preferably mated with rectilinear sections having the same angle of inclination to the axis of symmetry of the wave line outlining the cross section of the cooled plate, which angle equals half the angle of the diffuser.
~,30 It has been found preferable for the angle of inclin-ation of the rectilïnear section to be set at an angle of 8 to ~5 deg~ relative to the axis of symmetry of the wave B
ll91S9 line outlining the cross-sectional profile Or ~he cooled plate.
To ensure uniform distribution o~ a '~eat carrier over the passages formed in the intertubular space of a heat exchanger, it is necessary that the diverging-co~-verging sections of the passages should have, at the point of the heat carrier entrænce to and its exit from tne stac~ of cooled plates, rectilinear sections l~ing in the plane of symmetry of the wave line outlining the cross-sectional profile of the cooled plates.
The bending radius of the projections and depressions of each cooled plate should no~ be more than twenty times the thickness of the cooled plate material.
It is expedient that the orientation of the edges of the braached holes, formed in the cooled plates to receive tubes therein, should be oriented in the opposi-tely reflected lashion relative to the respective projec-tion~ and depressions of the cooled plates.
The edges o~ the broached holes are pre~erably for-med throughout their surfaces, around the peripher~y of each tube, ~ he use of the heat exchanger con~truction of the inventio~, for example, as the tractor water-to-air cooler, permits, all other conditions being equal, the aize and weight thereof to be reduced 1.5 to 2 times, as 9~59 , :.
compared with the known heat exchanger~ o~ similar ~pe, to say nothing o~ its higher resistance to contamination, wherein air-suspended particles of dust and dirt are prevented ~rom penetrating into the air space t'nereof~
The invention will now be explained~ by way o* exam- -~
ple only, with reference to the acco~panying drawin~s, wherein:
.l is a general view o~ Q tube-and-plate heat exchanger o~ the invention;
Fig,2 is a view o~ one of the adjacent plates o~ a hcat exchanger, according to tl1e invention;
~ ig.3 is a view of another type of the adjacent pla-tes o~ a heat exchanger, according to the invention; and ~ ig,4 i~ a cross section o~ one o~ the plates o~ a heat exchanger, according to the invention.
Re~erring now to the above drawings, and to Fig.l in particular, there is shown therein a tube-and-plate heat exchanger which comprises a plurality o~ plain tubes I arranged, in the pre~erred embodiment, in parallel rows and intended ~or the passage o~ one heat carrier.
~ounted on the tubes I and spaced from one another at a-n interval h are upper adjacent plates 2 and lower adjacent platcs 3, which are cooled with air. In cross section the air-cooled plates 2 and 3 are pro~iled so as to fo~n, in the air flow direction, a continuous wave line. The :. ,' ".
, i, .
" - ' . ...
~l~9~S9 .~ -- 10 --. . , adjacent upper and lower air-cooled plates 2 ~nd 3 are arranged in the heat exchallger so that projections 4 and depressions 5 of each upper adjacent plate 2 face res-pective projections 6 and de-pressions 7 of each lowe~
adjacent plate 3. Thl~s, the intertubular space of the heat exchan~er is formed with passages having continuously alternating di~erging-converging sections with the ~ame diffuser diverging and converging angle ~.
- For reliable connection of the plain tube~ I with the air-cooled pla~es 2,3~the latter broached to have holes 8 with edges 9, In the upper plate 2 (~ig,2) and the lower plate 3 (~igo3) adjacent therewith, t'ne edges 9 o~ the broached holes 8 are oriented in opposite-ly reflected fashion in relation to the respective projections 4 (Fig,2) and 6 (~ig~3) and the depressions 5 (~ig,2) and 7 (~ig,3), The projections 4 (Fig,4) and the depressions 5 of the cooled plates 2 mate with one another along rectilinear section~ 10 which have the same angle ~ of inclination to the axis of sym~etry of the wave line outlining the profile of the cooled plate 2, The pro~ections 5 (~ig,l) and thedepressions 7 of the plates 3 mate with one another in a similar manner~ As a result, the intertubular space of the heat exchanger is formed with passages having continuous symmetric diverging-converging sections wherein the angle ~ of divergence is equal to that of convergence, ,, .
:, :
" ::
: ' , , ~
~ he v~ave line outlining the profile of the cooled plates 2, 3 (Fig.4) is con~ined, from the side o~ ~he cooling air entry to and exit therefrom, by rectilinear sections 12 lying on the axis II of ita sy~metry. Thus 9 in the cooling air flow direction i~dicated by an arrow~
the cooled plate~ 2, 3 (~ig.l) are con~ined by plane-paral- -lel sections.
The projections 4,6 and the depression~ 5~7 are made round over the bending radius R (Fig.4).
Inten~ification o~ the convective heat e~change process in the heat exchanger con~truction of the inve~tion is conditioned by the following factors, As the cooling air flows through the intertubular space of the heat exchanger, the con~ective heat exchange prOCe88 i8 s.tepped up in the passages due to the fact that the loas of hydrodynamic stability of the heat car-rier flow laminar structure takes place primarily on the diffuser walls in the diverging sections o~ the air passages. Ths diffuser flare angle ~ (Fig.l), at which the- ;
re takes place primary loss of hydraulic stability in the flo~ laminar structure, i~ called critical. A minimum va-lue of this critical angle,enabling favourable hydrody-namic conditions for the flow of air in the annular dif-fu~er, ha~ been found to be 8 deg. With the diffuser flaring angle ~ ranging from 16 to 90 deg~ in excess of the critical angle, the 103s of hydrodynamic stabilit~
,~
~ ,.,: : , l9~S9 of the air flow laminar structure in the diverging secti-ons of the pas~a~es fo~med in the intertubular space is a continuous process. A~ a reæult, ~ortice~ are generated on the dif~user walls in the wall layer of the heat carrier at the corresponding flaring angle ~ of the diffuser and under requisite flow conditions. ~his 9 in turn9 re~ul~s in a sharp-increase of eddy viscosity and heat conduction of this layer, a~ well as in the temperature gradie~t and heat flow den~ity. Hence is a substantial increase (up to 2.5 times) in the coefficient ~ of heat transfer ~ro~
the cooling air to the walls of the diverging-converging passages. It is to be noted that no additional energy is required for the core of the air ~low. This can be expla-ined by the fact that the projection~ 4,6 and the depr%ssions ~-5, 7 of the continuously alternating divergln~-convergin~
~ections mate with one another over the radius R (~ig.4).
A change of R within the range of R~ 20/~ 9 ~here ~ is the thickne~s of the material o~ the cooled plate 29 3 (~ig.l), results in that three-dimensional vortex, disposed in the wall layer of the heat carrier, i9 generated along the walls o~ the diverging-co~verging sections of the pas~ages. Here the hydrodynamic ~tructure in the core of the flow remaine the same as in a smooth passage throughout the entire operating range of the heat carrier flow.
'~
-` ~119lS9 Therefore, in the heat exchanger of the invention the additional energy9 required for the intensification of the heat exchange process, is consumed primarily ~or the generation of the wall three-dimensional ~ortex which accounts for a ~harp incraase in the tubular visco~ity and heat conduction of the wall layer o~ the low, as compared with the same parameters obtained in a smooth pas~age. This factor 8110w8 for a substantial increase in the heat transfer to be obtained at relatevely low energy input required for ~he delivery o~ the heat carrier in the diverging-converging tgpes o~ passages. Wi~h regard to diverging -converging type~ of pa~ages, a maximum increaae in the heat transfer coefficient ~1 9 being ~ , 52.2-2,5 with an increase in the los~ of pressure of the heat carrisr being ~ = 2~2.-2.5, ~her~ are respe¢tively heat trans~er coe~icients in the diverging-¢onverging and smooth passages; ~p , apl are respectively the pre~sure 103ses in the heat carrier in the diverging-con~erging and smooth passages. Thus it has become possible to effe¢t ~ubstantial reduction (up to 2-2.5 times) in size, weight and cost of the no-in-use water-to-air coolers for use in tractors, automobiles and diesel locomoti~es, by introducing diverging-converging type3 of pas3age~
in~tead of ~mooth type. of passag~s used in the .prior-art heat exchanger.
, : ' '; '~
. ~ :
~ he heat exchanger according to the invention is well adapted to operate on contaminated air wherein the generation of vortices on the walls of the pa~age~
prevents the air-su~pended particles of du~t and dirt from being deposited thereon due to the action of centrifugal forces in the wall area, effective to carry out these particles through the in~ermidiary layer into the core of the flow to be thereafter discharged from the cooler together with the main air flow.
With a purpose of creating ~avourable condi~ions for intencifying the convective heat exchange process in the diverging-converging passages formed by the adjacent cooled plates 2,3, ths projections 4,6 and the depressions 5,7 of the~e plates mate with one another through the rectilinear section~ 10 (Fig.4) having the same angle ~ of inclination to the axis II of symmetry of the wave line outlining the pa~age profile. A~ the result, the air heat exchange sur~ace i3 defined by symmetric diverging-converging ~ection of the pas~ages. The equality of angle ~ is necCessitated by that one side of the cooled plate 2,3 (Fig,l) is, for example, the diverging section of the air pa~sage, the other side thereof being the converging ~ection of the passage and vice ver~a. The ab~ence of symmetry of the angle~ ~ (Fig.4) of inclination in conju-gating rectilinear ~ections 10 may result in a relative-ly large length of the diverging ~ection of the passages .
-.
. . . ~
: ~ .
~` 11~9~59 at one side of the cooled plate 2,3 (Fig.l) which rna'~e for da~lping of vortices in the ~Jall layer of the air flow. Simultaneously, the length of the diverging section of the passage will be reduced on the other side of t'ne cooled plate 2,3, along which three-dim~nsional vor~ices are generated with an ensuing intensificatio~ of the con-vective heat exchange process.
Depending on the operating range of the heat car-rier flow, the angle ~ (Fig.~) of inclination of the conjugating rectilinear sections 10 is altered within the range o~ ~ = 8 to 45 deg., which corresponds to the range of change in the diffuser flare angle ~ (Fig.l) =
The present invention relates to heat engineerin~, and more particularly, to a tube-and-plate heat excnarger, ; This invention can find utility in the manufacture of air-to-air heat exchangers, and liquid-to-air `neat exchangers intended ~or various applications in the constructions o~ air coolers and evaporators required for condensation and evaporation o~ various liquids, This type of heat exchanger is well adapted to operate on both conta,minated and uncontaminated air, The heat exchanger construction o~ t'ne inven~io-n is mo~t advantageous for use as water-to-air and oil-to-air cooler3 incorporated in cooling systems of both movable and stationary power plants.
There is known a tube-and-plate heat exchanger used in the constructions of water-to-air coolers installed in motor vehicles, tractors and diesel locomotives, This type of heat exchanger comprises a plurality of plain and round tubes for the passage of a cooled workint fluid, These tubes are received ln respective through hole~ formed in flat cooled plates, The tubes for the `~
passage of a worlcing fluid can be arranged either in parallel rows or in staggered manner, Thus, t'ne coolers of this type are constructed so as to permit plain rectangular passages or channels to be ~ormed in the ,' ' ' ~
. .
. ~
.. ~ , ' .
~ . . , - .
~.~ l9~S9 intertubular space thereof. These channels or passages are not provided with vortex generators required to intenesify the heat exchanging process in the intertubular space. This intensification of the heat exchanging pro-cess is necessitated by that water-to-air coolers of various power plants operate under conditions where t'ne over-all heat trasfer coefficient K of the cooler is approximately equal to the air heat emission coeffi-cient ~ , i.e. K~ . Therefore, a reduction in size and weight of the water-to-air calls for the increase in K, which is single-valued as ~1. The value of d~is ~nown to be the smallest in plain passages. Therefore 9 the prior-art tube-and-plate heat exchanger is large in size and weight.
The tube-and-plate heat exchangers of the aforedes-cribed construction can be reduced in size and vreight only by way of increasing the hea,t emlssion coeffi~ient oL~
which is possible to carry out by producing the air flow turbulence in the cooler passages with the aid of various vortex generating means.
There is also known in the art a tube-and-plate heat exchanger which comprises plain tubes for the passage of cooled water, the tubes being arranged either in parallel rows or in staggered fashion. In order to intensify the procees of convective heat exchenge in the intertubuler , :
' 1119~59 ~ . ~
space, the cooled plates are profiled, in thc travelling direction of air flow, so as to ~orrn a continucus symmetric wave line, with the cooled plates being arranged in the cooler tube bundle so that projections and depres-sions of each pair of the adjacent plates are equidistant ~rom one another. As a result, there are formed, in the interspace between the adjacent cooled plates, passages for cooling air, which have undulatory shape if viewed in the travelling direction o~ the air flow.
The Xnown water-to-air coolers have been -tested to show insufficient~y high thermohydraulic effectiveness.
The reason for this lies in that the increase in the heat emission coe~-ficient ~lis lagging in such passages very much behind that of the energy input required for stepping up the process of heat transfer as compared with smooth passages. This can be exp~ained by that vortices, formed by a flow of air behind and before each turn in such passages, are equal to, or commensurate with, the height of projection of the waving passage. It should be added that the height of the projection in these types of passages is equal to, or commensurate with, the hyd-raulic passage diameter. As a result, the amount of ener-gy delivored to the cooled air in waving passages is lost (by 70 to 80%) to effect transition to turbulence in the core of the flow wnere the temperature field gradient and that of the heat flow den~ity are smell , ........................................................................ .
; ' . , .
. : ' : ."
.
~119~59 enou~h to bring about æny substantial increase in the heat flow density. Since these large-scale vortices pos-sess con~iderable kinetic energy, they,on overcoming the forces o~ ~iscosity and friction, are gradually disso-ciating to be therea~ter displaced to the wall layer of air. This results in that the wall layer is made turbu-lent, with the turbulence heat conduction and the heat flow density increasing therein. Therefore, the heat exchange process in the waving passage is intensi~ied ;~ by the turbulence of the wall layer of the air flow and not in itis core, though the loss o~ additional energy fed to the air flow in the waving passage so as to induce turbulence in the core of the flow is much greater than that required to produce turbulence in the wall layer : thereof, And this is the main reason for low thermohydra- -ulic e~ectiveness of the heat exchanging sur~ace of the ; prior-art tube-and-plate heat exchanger.
A,'~ An object o~ the present invention is to provide a tube-and-plate heat exchanger o~ the type to permit thermohydraulic effectiveness to be enhanced by inten-sifying convective heat exchange in the intertubular ~pace thereof~
,~ ~nother object of the invention i9 to provide a tube-and-plate heat exchanger which will be smaller in ~ize and weight.
,'; ' ;, . .
, ....
''. ', ~ ; ~` ~ ' . .
lll91S9 Still another o~ject of the invention is to provide a tube-and-plate heat exchanger which i5 well adapted to operate on contaminated cooled air.
Accordingly, the present ïnvention provides a tube-and-plate heat exchanger comprising: a stack of plates spaced with a gap from one another; each of said gaps serving as a - passage; broached holes formed in each of the plates of the stack with the holes of the different plates being in register with each - other; a bundle of tubes corresponding in number to the said holes of each plate, each tube passing through each set of aligned holes; two heat carriers having different temperatures, with heat exchange takins place therebetween, one of said heat carriers flowing through said tubes, the other one flowing through said passages; each of said plates being profiled in s the flow direction of the said second mentioned heat carrier as a continuous wave line with alternating projections and depressions; diverging and converging sections of said pas~ages formed by said projections and depressions of each of said plates being disposed so as to face the respective projections and depressions of one of said plates adjacent therewith; said diverging sections defining a flaring angle; said flaring angle exceeding the critical angle of primary loss of hydrodynamic stability of laminar structure of the flow of said second mentioned heat carrier.
Projections and depressions of the cooled plates are preferably mated with rectilinear sections having the same angle of inclination to the axis of symmetry of the wave line outlining the cross section of the cooled plate, which angle equals half the angle of the diffuser.
~,30 It has been found preferable for the angle of inclin-ation of the rectilïnear section to be set at an angle of 8 to ~5 deg~ relative to the axis of symmetry of the wave B
ll91S9 line outlining the cross-sectional profile Or ~he cooled plate.
To ensure uniform distribution o~ a '~eat carrier over the passages formed in the intertubular space of a heat exchanger, it is necessary that the diverging-co~-verging sections of the passages should have, at the point of the heat carrier entrænce to and its exit from tne stac~ of cooled plates, rectilinear sections l~ing in the plane of symmetry of the wave line outlining the cross-sectional profile of the cooled plates.
The bending radius of the projections and depressions of each cooled plate should no~ be more than twenty times the thickness of the cooled plate material.
It is expedient that the orientation of the edges of the braached holes, formed in the cooled plates to receive tubes therein, should be oriented in the opposi-tely reflected lashion relative to the respective projec-tion~ and depressions of the cooled plates.
The edges o~ the broached holes are pre~erably for-med throughout their surfaces, around the peripher~y of each tube, ~ he use of the heat exchanger con~truction of the inventio~, for example, as the tractor water-to-air cooler, permits, all other conditions being equal, the aize and weight thereof to be reduced 1.5 to 2 times, as 9~59 , :.
compared with the known heat exchanger~ o~ similar ~pe, to say nothing o~ its higher resistance to contamination, wherein air-suspended particles of dust and dirt are prevented ~rom penetrating into the air space t'nereof~
The invention will now be explained~ by way o* exam- -~
ple only, with reference to the acco~panying drawin~s, wherein:
.l is a general view o~ Q tube-and-plate heat exchanger o~ the invention;
Fig,2 is a view o~ one of the adjacent plates o~ a hcat exchanger, according to tl1e invention;
~ ig.3 is a view of another type of the adjacent pla-tes o~ a heat exchanger, according to the invention; and ~ ig,4 i~ a cross section o~ one o~ the plates o~ a heat exchanger, according to the invention.
Re~erring now to the above drawings, and to Fig.l in particular, there is shown therein a tube-and-plate heat exchanger which comprises a plurality o~ plain tubes I arranged, in the pre~erred embodiment, in parallel rows and intended ~or the passage o~ one heat carrier.
~ounted on the tubes I and spaced from one another at a-n interval h are upper adjacent plates 2 and lower adjacent platcs 3, which are cooled with air. In cross section the air-cooled plates 2 and 3 are pro~iled so as to fo~n, in the air flow direction, a continuous wave line. The :. ,' ".
, i, .
" - ' . ...
~l~9~S9 .~ -- 10 --. . , adjacent upper and lower air-cooled plates 2 ~nd 3 are arranged in the heat exchallger so that projections 4 and depressions 5 of each upper adjacent plate 2 face res-pective projections 6 and de-pressions 7 of each lowe~
adjacent plate 3. Thl~s, the intertubular space of the heat exchan~er is formed with passages having continuously alternating di~erging-converging sections with the ~ame diffuser diverging and converging angle ~.
- For reliable connection of the plain tube~ I with the air-cooled pla~es 2,3~the latter broached to have holes 8 with edges 9, In the upper plate 2 (~ig,2) and the lower plate 3 (~igo3) adjacent therewith, t'ne edges 9 o~ the broached holes 8 are oriented in opposite-ly reflected fashion in relation to the respective projections 4 (Fig,2) and 6 (~ig~3) and the depressions 5 (~ig,2) and 7 (~ig,3), The projections 4 (Fig,4) and the depressions 5 of the cooled plates 2 mate with one another along rectilinear section~ 10 which have the same angle ~ of inclination to the axis of sym~etry of the wave line outlining the profile of the cooled plate 2, The pro~ections 5 (~ig,l) and thedepressions 7 of the plates 3 mate with one another in a similar manner~ As a result, the intertubular space of the heat exchanger is formed with passages having continuous symmetric diverging-converging sections wherein the angle ~ of divergence is equal to that of convergence, ,, .
:, :
" ::
: ' , , ~
~ he v~ave line outlining the profile of the cooled plates 2, 3 (Fig.4) is con~ined, from the side o~ ~he cooling air entry to and exit therefrom, by rectilinear sections 12 lying on the axis II of ita sy~metry. Thus 9 in the cooling air flow direction i~dicated by an arrow~
the cooled plate~ 2, 3 (~ig.l) are con~ined by plane-paral- -lel sections.
The projections 4,6 and the depression~ 5~7 are made round over the bending radius R (Fig.4).
Inten~ification o~ the convective heat e~change process in the heat exchanger con~truction of the inve~tion is conditioned by the following factors, As the cooling air flows through the intertubular space of the heat exchanger, the con~ective heat exchange prOCe88 i8 s.tepped up in the passages due to the fact that the loas of hydrodynamic stability of the heat car-rier flow laminar structure takes place primarily on the diffuser walls in the diverging sections o~ the air passages. Ths diffuser flare angle ~ (Fig.l), at which the- ;
re takes place primary loss of hydraulic stability in the flo~ laminar structure, i~ called critical. A minimum va-lue of this critical angle,enabling favourable hydrody-namic conditions for the flow of air in the annular dif-fu~er, ha~ been found to be 8 deg. With the diffuser flaring angle ~ ranging from 16 to 90 deg~ in excess of the critical angle, the 103s of hydrodynamic stabilit~
,~
~ ,.,: : , l9~S9 of the air flow laminar structure in the diverging secti-ons of the pas~a~es fo~med in the intertubular space is a continuous process. A~ a reæult, ~ortice~ are generated on the dif~user walls in the wall layer of the heat carrier at the corresponding flaring angle ~ of the diffuser and under requisite flow conditions. ~his 9 in turn9 re~ul~s in a sharp-increase of eddy viscosity and heat conduction of this layer, a~ well as in the temperature gradie~t and heat flow den~ity. Hence is a substantial increase (up to 2.5 times) in the coefficient ~ of heat transfer ~ro~
the cooling air to the walls of the diverging-converging passages. It is to be noted that no additional energy is required for the core of the air ~low. This can be expla-ined by the fact that the projection~ 4,6 and the depr%ssions ~-5, 7 of the continuously alternating divergln~-convergin~
~ections mate with one another over the radius R (~ig.4).
A change of R within the range of R~ 20/~ 9 ~here ~ is the thickne~s of the material o~ the cooled plate 29 3 (~ig.l), results in that three-dimensional vortex, disposed in the wall layer of the heat carrier, i9 generated along the walls o~ the diverging-co~verging sections of the pas~ages. Here the hydrodynamic ~tructure in the core of the flow remaine the same as in a smooth passage throughout the entire operating range of the heat carrier flow.
'~
-` ~119lS9 Therefore, in the heat exchanger of the invention the additional energy9 required for the intensification of the heat exchange process, is consumed primarily ~or the generation of the wall three-dimensional ~ortex which accounts for a ~harp incraase in the tubular visco~ity and heat conduction of the wall layer o~ the low, as compared with the same parameters obtained in a smooth pas~age. This factor 8110w8 for a substantial increase in the heat transfer to be obtained at relatevely low energy input required for ~he delivery o~ the heat carrier in the diverging-converging tgpes o~ passages. Wi~h regard to diverging -converging type~ of pa~ages, a maximum increaae in the heat transfer coefficient ~1 9 being ~ , 52.2-2,5 with an increase in the los~ of pressure of the heat carrisr being ~ = 2~2.-2.5, ~her~ are respe¢tively heat trans~er coe~icients in the diverging-¢onverging and smooth passages; ~p , apl are respectively the pre~sure 103ses in the heat carrier in the diverging-con~erging and smooth passages. Thus it has become possible to effe¢t ~ubstantial reduction (up to 2-2.5 times) in size, weight and cost of the no-in-use water-to-air coolers for use in tractors, automobiles and diesel locomoti~es, by introducing diverging-converging type3 of pas3age~
in~tead of ~mooth type. of passag~s used in the .prior-art heat exchanger.
, : ' '; '~
. ~ :
~ he heat exchanger according to the invention is well adapted to operate on contaminated air wherein the generation of vortices on the walls of the pa~age~
prevents the air-su~pended particles of du~t and dirt from being deposited thereon due to the action of centrifugal forces in the wall area, effective to carry out these particles through the in~ermidiary layer into the core of the flow to be thereafter discharged from the cooler together with the main air flow.
With a purpose of creating ~avourable condi~ions for intencifying the convective heat exchange process in the diverging-converging passages formed by the adjacent cooled plates 2,3, ths projections 4,6 and the depressions 5,7 of the~e plates mate with one another through the rectilinear section~ 10 (Fig.4) having the same angle ~ of inclination to the axis II of symmetry of the wave line outlining the pa~age profile. A~ the result, the air heat exchange sur~ace i3 defined by symmetric diverging-converging ~ection of the pas~ages. The equality of angle ~ is necCessitated by that one side of the cooled plate 2,3 (Fig,l) is, for example, the diverging section of the air pa~sage, the other side thereof being the converging ~ection of the passage and vice ver~a. The ab~ence of symmetry of the angle~ ~ (Fig.4) of inclination in conju-gating rectilinear ~ections 10 may result in a relative-ly large length of the diverging ~ection of the passages .
-.
. . . ~
: ~ .
~` 11~9~59 at one side of the cooled plate 2,3 (Fig.l) which rna'~e for da~lping of vortices in the ~Jall layer of the air flow. Simultaneously, the length of the diverging section of the passage will be reduced on the other side of t'ne cooled plate 2,3, along which three-dim~nsional vor~ices are generated with an ensuing intensificatio~ of the con-vective heat exchange process.
Depending on the operating range of the heat car-rier flow, the angle ~ (Fig.~) of inclination of the conjugating rectilinear sections 10 is altered within the range o~ ~ = 8 to 45 deg., which corresponds to the range of change in the diffuser flare angle ~ (Fig.l) =
2~ (Fig.4) = 16 to 90 deg.
'I'he change of angle ~ within the above range makes it possible for the heat transfer coefficient ~ 1 to grow faster or at the same rate with the loss of pressure, as compared with the smooth heat exchange sur~ace. Eowe-ver, a decrease in the angle ~ below 8 deg. fails to bring about any significant intensification of the con-vective heat exchange process, which makes it imprac-tical to develop tube-and-plate heat exchangers o~
smaller size and weight, and at reduced expences. If the angle'~ of inclination is less than ~ deg., the converging section of the air passage will be substan-tially increased in length, which, in turn, will result in it~ enhanced stabilizing effect on the turbulent 11~9~S9 .
structure o~ the ~low in the passage. ArA increased length o~ the converging sec-~ion of the passage will result in -the damping of vortices at the very begi.~nir~
of the converging section, with the remaining leng~h thereof being inef~ective to promote any significant intensification o~ the convective heat exchange process.
A~ increase in the angle ~ ol inclination above 45 deg.
will bring about a f`aster rate of pressure losses in the heat carrier in relation to the growth of the heat transfer coefficient (~ , as compared to the parameters in the similar passages but of smooth type.
This, therefore, Iails to ensure favourable conditions required ~or highly intensified convective heat e~changi~g proce~s, which leads to an emmensely high consumption of energy nea~ded for the heat carrier delivery to obtain a requisite degree of intensification of the convective heat exchange process. An increase of the angle ~
above 45 deg. results in an enhanced stabilizing e~fect o~ the converging section of the passage on the development of tubular structure of the heat carrier flow at the exit from the dive~ing section of the pas-sage . As a result of this~ the three-dimensional vor-tices ~enerated at the diverging section of the passage are damped almost completely. As this happens, the vortices ~ormed in the depressions 5,7 change their :' . ; , ~ . .~
lll9~S9 three-dimensional structure for two-dimensional. ~he presence of two-dimensional vortices in the depressions 5, 7 have but insignificant effect on the intensi~ication of the heat exchange process. I~ addition, a subs-tantional amount of energy is required to keep them active which is inexpe,dient~
With the purpose of insuring uniform distribution of air over the passages in the intertubular space o~ the tube-and-plate heat sxchan~er~ the wave line outlining the profile of the cooled plates 2, 3 is confined, at the air inle~ and outlet places, by the rectilinear sec-tion 12 (Fig.4) lying on the axis II of its symme~r~.
In this case, the adjacent passages will have the same resistarlce to thereby result in uniform distribution of air over the passages of the intertubular space. Hence is the enhanced ther~modynamic ef~ectiveness of the tube-and-plate heat exchanger.
In the preferred embodiment of the invention the adjacent plates 2 and 3 are formed with broached holes 8 the edges 9 of which are oriented in oppositely reflected ~ashion to the respective projections 4 and 6 a~d the depressions 5 and 7. It is to be emphasized that this type of orientation of the edges 9 of the broached holes 8 is the sole possible to enable the heat exchanger construction according to the invention wherein the intertubular space is ~ormed with passages having diverging-converging sections.
In order to enable the best possible therrnal con~ac~
between the cooled plates 2,3 with the plain tubes I9 obtained by a sint~ring method ef~ected in furnaces the ~-projections 4 and 6 and the depressions 5 and 7 are not provided at those places of the cooled plates 2 and 3 which are fo~med with.the broac~ed holes 8. If ~he.holes 8 are broached in the cooled plates 2 and 3 over the undulatory surface, the generatrix o~ the surface of the edges 9 of the holes 8 will not be similar to that o~ the plain tubes which will ~ail to ensure their in-timate mating (after sintering) with the surface of the plain tube I throughout the contour o~ the edges 9 of the holes 8, and will impair thermal contact between the cooled plates 2 and 3 with the plain tube 1. ~he use of the tube-and-plate heat e2changer as the water-to-air cooler for tractors has made it possible to carry out reduction in size and weight thereof by 1.5 to 2 times, all other cond~tions being equal. Taking into account the ~act that the coolers Intended for use in tractors, automobiles and diesel locomotives are manufactured from expensive and scarce non-ferrous metals, such as brass, commercially pure electrolitic copper and tin solder, as well as considering ~ass production of these coolers, ~ ,.
-,~ ~91,~g estimated at millions o~ pieces per year, tha applica-tion o~ the tube-and-plate heat exchanger ~or the above purposes will gi~e substantial eco~omic e~fect.
'I'he change of angle ~ within the above range makes it possible for the heat transfer coefficient ~ 1 to grow faster or at the same rate with the loss of pressure, as compared with the smooth heat exchange sur~ace. Eowe-ver, a decrease in the angle ~ below 8 deg. fails to bring about any significant intensification of the con-vective heat exchange process, which makes it imprac-tical to develop tube-and-plate heat exchangers o~
smaller size and weight, and at reduced expences. If the angle'~ of inclination is less than ~ deg., the converging section of the air passage will be substan-tially increased in length, which, in turn, will result in it~ enhanced stabilizing effect on the turbulent 11~9~S9 .
structure o~ the ~low in the passage. ArA increased length o~ the converging sec-~ion of the passage will result in -the damping of vortices at the very begi.~nir~
of the converging section, with the remaining leng~h thereof being inef~ective to promote any significant intensification o~ the convective heat exchange process.
A~ increase in the angle ~ ol inclination above 45 deg.
will bring about a f`aster rate of pressure losses in the heat carrier in relation to the growth of the heat transfer coefficient (~ , as compared to the parameters in the similar passages but of smooth type.
This, therefore, Iails to ensure favourable conditions required ~or highly intensified convective heat e~changi~g proce~s, which leads to an emmensely high consumption of energy nea~ded for the heat carrier delivery to obtain a requisite degree of intensification of the convective heat exchange process. An increase of the angle ~
above 45 deg. results in an enhanced stabilizing e~fect o~ the converging section of the passage on the development of tubular structure of the heat carrier flow at the exit from the dive~ing section of the pas-sage . As a result of this~ the three-dimensional vor-tices ~enerated at the diverging section of the passage are damped almost completely. As this happens, the vortices ~ormed in the depressions 5,7 change their :' . ; , ~ . .~
lll9~S9 three-dimensional structure for two-dimensional. ~he presence of two-dimensional vortices in the depressions 5, 7 have but insignificant effect on the intensi~ication of the heat exchange process. I~ addition, a subs-tantional amount of energy is required to keep them active which is inexpe,dient~
With the purpose of insuring uniform distribution of air over the passages in the intertubular space o~ the tube-and-plate heat sxchan~er~ the wave line outlining the profile of the cooled plates 2, 3 is confined, at the air inle~ and outlet places, by the rectilinear sec-tion 12 (Fig.4) lying on the axis II of its symme~r~.
In this case, the adjacent passages will have the same resistarlce to thereby result in uniform distribution of air over the passages of the intertubular space. Hence is the enhanced ther~modynamic ef~ectiveness of the tube-and-plate heat exchanger.
In the preferred embodiment of the invention the adjacent plates 2 and 3 are formed with broached holes 8 the edges 9 of which are oriented in oppositely reflected ~ashion to the respective projections 4 and 6 a~d the depressions 5 and 7. It is to be emphasized that this type of orientation of the edges 9 of the broached holes 8 is the sole possible to enable the heat exchanger construction according to the invention wherein the intertubular space is ~ormed with passages having diverging-converging sections.
In order to enable the best possible therrnal con~ac~
between the cooled plates 2,3 with the plain tubes I9 obtained by a sint~ring method ef~ected in furnaces the ~-projections 4 and 6 and the depressions 5 and 7 are not provided at those places of the cooled plates 2 and 3 which are fo~med with.the broac~ed holes 8. If ~he.holes 8 are broached in the cooled plates 2 and 3 over the undulatory surface, the generatrix o~ the surface of the edges 9 of the holes 8 will not be similar to that o~ the plain tubes which will ~ail to ensure their in-timate mating (after sintering) with the surface of the plain tube I throughout the contour o~ the edges 9 of the holes 8, and will impair thermal contact between the cooled plates 2 and 3 with the plain tube 1. ~he use of the tube-and-plate heat e2changer as the water-to-air cooler for tractors has made it possible to carry out reduction in size and weight thereof by 1.5 to 2 times, all other cond~tions being equal. Taking into account the ~act that the coolers Intended for use in tractors, automobiles and diesel locomotives are manufactured from expensive and scarce non-ferrous metals, such as brass, commercially pure electrolitic copper and tin solder, as well as considering ~ass production of these coolers, ~ ,.
-,~ ~91,~g estimated at millions o~ pieces per year, tha applica-tion o~ the tube-and-plate heat exchanger ~or the above purposes will gi~e substantial eco~omic e~fect.
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A tube-and-plate heat exchanger comprising:
a stack of plates spaced with a gap from one another;
each of said gaps serving as a passage;
broached holes formed in each of the plates of the stack with the holes of the different plates being in register with each other;
a bundle of tubes corresponding in number to the said holes of each plate, each tube passing through each set of aligned holes;
two heat carriers having different temperatures, with heat exchange taking place therebetween, one of said heat carriers flowing through said tubes, the other one flowing through said passages;
each of said plates being profiled in the flow direction of the said second mentioned heat carrier as a continuous wave line with alternating projections and depressions;
diverging and converging sections of said passages formed by said projections and depressions of each of said plates being disposed so as to face the respective projections and depressions of one of said plates adjacent therewith, said diverging sections defining a flaring angle;
said flaring angle exceeding the critical angle of primary loss of hydrodynamic stability of laminar structure of the flow of said second mentioned heat carrier.
a stack of plates spaced with a gap from one another;
each of said gaps serving as a passage;
broached holes formed in each of the plates of the stack with the holes of the different plates being in register with each other;
a bundle of tubes corresponding in number to the said holes of each plate, each tube passing through each set of aligned holes;
two heat carriers having different temperatures, with heat exchange taking place therebetween, one of said heat carriers flowing through said tubes, the other one flowing through said passages;
each of said plates being profiled in the flow direction of the said second mentioned heat carrier as a continuous wave line with alternating projections and depressions;
diverging and converging sections of said passages formed by said projections and depressions of each of said plates being disposed so as to face the respective projections and depressions of one of said plates adjacent therewith, said diverging sections defining a flaring angle;
said flaring angle exceeding the critical angle of primary loss of hydrodynamic stability of laminar structure of the flow of said second mentioned heat carrier.
2. A heat exchanger as claimed in claim I, in which said projections and depressions of said plates mate with one another through rectilinear sections having an angle of inclination to the axis of symmetry of said wave line; said angle of inclination of each of said rectili-near sections being equal half the flaring angle of the diverging sections.
3. A heat exchanger as claimed in claim I comprising rectilinear section of said plates at the inlet and outlet of said second mentioned heat carrier from the stack of said plates, said rectilinear sections lying in the plane of symmetry of said wave line.
4. A heat exchanger as claimed in claim I, wherein said projections and depressions of said plates have the ben-ding radius not exceeding twenty times the thickness of material used for said plates.
5. A heat exchanger as claimed in claim I,comprising edges of said broached holes; the edges of said broached holes of said plates adjacent therewith being oriented in the oppositely reflected fashion relative to the respective said projections and depressions.
6. A heat exchanger as claimed in claim 2, in which said angle of inclination of said rectilinear section to the axis of symmetry is 8 to 45 deg.
7. A heat exchanger as claimed in claim 5, in which said edges of said broached holes are formed throughout their surfaces around the periphery of said tubes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000336275A CA1119159A (en) | 1979-09-25 | 1979-09-25 | Tube-and-plate heat exchanger |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000336275A CA1119159A (en) | 1979-09-25 | 1979-09-25 | Tube-and-plate heat exchanger |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1119159A true CA1119159A (en) | 1982-03-02 |
Family
ID=4115202
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000336275A Expired CA1119159A (en) | 1979-09-25 | 1979-09-25 | Tube-and-plate heat exchanger |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1119159A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11592238B2 (en) | 2017-11-23 | 2023-02-28 | Watergen Ltd. | Plate heat exchanger with overlapping fins and tubes heat exchanger |
-
1979
- 1979-09-25 CA CA000336275A patent/CA1119159A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11592238B2 (en) | 2017-11-23 | 2023-02-28 | Watergen Ltd. | Plate heat exchanger with overlapping fins and tubes heat exchanger |
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