US2521369A

US2521369A - Multifluid heat exchanger

Info

Publication number: US2521369A
Application number: US561766A
Authority: US
Inventors: Holm Sven; Karlsson Per Hilmer
Original assignee: Air Preheater Co Inc
Current assignee: Alstom Power Inc
Priority date: 1944-11-03
Filing date: 1944-11-03
Publication date: 1950-09-05
Anticipated expiration: 1967-09-05

Description

Sept 5, 1950 l s. HoLM Erm. 2,521,369

MULTIFLUID HEAT EXCHANGER 3 sheets-Sheet 2 Filed Nov. 3, 1944 INVENToRs Sven fa/w BYPeL/Ydmer IIa/rissa 5, 1950 s. HQLM ETAL uULTIFLuIn HEAT maman 3 Sheets-Sheet 3 Filed Nov. 3, 1944 INVENTOR. Sue/r Holm BY Per flilmerlfarlsson Pstenad sept s, 195o 2,521,369 MUL'rmUm HEAT nxcmncln LSven Holm and Per Hilmer Karlsson, Wellsvillo,

N. Y., assignors to The Air Preheater 'Corporation, New York, N. Y.

Application November 3, 1944, Serial No. 581,768

12 claims. (ci. 257-246) l The present invention relates to heat exchange apparatus and particularly to apparatus in which heat is transferred between three or more streams of iiuid. y

In the embodiments of the invention described herein the invention is incorporated in a plate type heat exchanger through the passages oi' which one iiuid is circulated to be cooled by indirect contact with two other fluids.

One use contemplated for the apparatus is to cool air to very low temperatures using oxygen and nitrogen both at temperatures substantially below 0 F. The air entering at a. temperature around 100 F. carries a certain amount of water vapor which sublimes to ice at low tempera-f tures. To dispose of the ice it is necessary to transpose the air and nitrogen streams so that the nitrogen re-evaporates the ice deposited from the air. The apparatus, therefore, works in two cycles, each of which must give the same performance as to heat exchange and pressure drop. The oxygen enters the apparatus at a lower temperature than the nitrogen but is required to leave at the same temperature and. therefore, receives heat from both the air andthe nitrogen.

A feature of the invention is a heat exchanger construction in which two of the streams of fluid may be switched or transposed with respect to their relation to each other without, however, changing the rate of heat' transfer among the three iiuids, the pressure drop through the exchanger for any fluid or the direction of iiow thereof. L

The invention will be best understood `upon consideration of the following detailed description of illustrative embodiments thereof when considered in conjunction with the accompanying drawings, in which:

Figure 1 is a vertical sectional elevation of a heat exchanger embodying the invention in apparatus having a series of concentric annular passages;

Figures 2 and 3 are transverse sectional views along the correspondingly designated section lines in Figure 1 and illustrate the connections of inlet and outlet ducts with the passages of the exchanger;

Figures 4 and 4a are sectional views on line 4-4 of Figure 1 illustrating the flow of the fluids during the two cycles of operation of the apparatus shown in Figures y1 to 3. v

v sages of the apparatus in Figure 9 with either a larger number of passages;

Figure 6 is a fragmentary sectional view on linel the apparatus during the second cycle of opera-- tion;

Figure 9 is a transverse sectional view showing another form oi apparatus in which two of the fluids are circulated through a single annulus in which independent passages are formed; and

Figures 10 and 11 are a sectional elevation and perspective view showing connection of the pasinlet and outlet headers for the fluids.

r In Figures 1 to 3, the four concentric wall- -members il, i2, Il and il denne a pair of adiacent annular passages I5, il extending longitudinally of the apparatus and a similarly disposed centrally located channel II. One of the cooling i'iuids (oxygen) enters the central channel I1 at one end of the apparatus through an inlet connection Il and is discharged from the opposite end of the exchanger through an outlet connection 2l. As shown in Figures 2 and 3 each of the annular passages il, I0 is divided into two semicircular parts by the diametrically located partitions IB; these annuli could be further subdivided if desired. At the upper end of the apparatus at the left hand side air to be cooled enters through an inlet connection 2i which communicates at the left hand or upper side of the partition it with the section 23 ci the outermost annular passage i5 and at the right hand or lower side of Fig. 2 of the partition il with the section 2B of the inner annular passage.' i8. At the lower end of the apparatus the outlet connection 24 for air commimicates in like man-4 ner with the lower ends of the semi-circular sec-E tions 2l, Il, one in each of the two annuli. The cold nitrogen enters the bottom of the apparatus` at the left hand side through an inlet connestion 3l which extends toward the center o! the apparatus but communicates at the ,right hand side ofthe partition Il only with the section It of the outer annulus I5 and at the left hand side of the partition Il with the section Il of the inner annulus. At the upper right hand side of the apparatus the nitrogen is discharged through a similarly connected outlet Il which communicates only with the upper ends of thesemi-

circular sections

28 and 28, one in each of the annuli Ii, I6. With connections so arranged the air flows eountercurrent with respect both to nitrogen and oxygen, which is the desired relationship for maximum heat transfer.

Plmdamentally the apparatus comprises a plurality of adjacent parallel fluid passages. In the form to be described immediately these -are in three concentric annuli. By covering the lower halves oi' the diagrams designated Figs. 4 and 4a it may be noted that if the air were to iiow in the entire outer annulus in `cycle I and in the intermediate annulus in cycle II, it is evident that the air would .be cooled to a much lower temperature in cycle II, where it would now between the cold oxygen and the cold nitrogen. Further. a discrepancy in the diameter of the annulae could also result in a difference in pressure drop due to difference in mass velocity. When nitrogen flows in the entire intermediate annulus in cycle I, the -oxygen does not exchange any heat with the air in that cycle. When in accordance with Vthe invention the air and nitrogen streams each flow in one-half or other adjacent fractional sections of the same annulus separated by a dividing wall, the total ow area for each of the two gases is the same in both cycles and the entire apparatus is balanced as to heat exchange relationship in the two cycles since the relations that exist on one side in one cycle have their counterparts on the other side in the second cycle. Heat is also exchanged at the same rate between the three gases in either cycle. The air and nitrogen iiow through the apparatus in substantially greater amount than the oxygen; therefore, extended surfaces in the form of ilns are used in the annulae Il. I6 carrying these gases. The hydraulic diameter of the channels between dns must be the same for air as for nitrogen because the pressure drop increases inversely as hydraulic diameter (also called equivalent diameter) is dened as equal to four times the area` of channel divided by the circumference. In heat transfer the hydraulic diameter of a passage depends on whatportion of its perimeter is' eifective as heat transfer surface, and is defined as four times the cross-sectional area divided by the portion of-perlmeter through which heat exchange takes place. The walls II, I2, I8 and Il are therefore spaced radially at such distances that the hydraulic diameter of the inner and outer annuli I5, I6 is the same. This applies also to Figs. 6 and 7 wherein the passages Il 2l are of greater radial width than passages Il and to obtain the same hydraulic di- For the same reason the fins are radially opposite each other in pairs, with the ilns in passage 3S having the same spacing on the circumference as the fins in passage I5, and the iinsinpassage 8i spacedradiallyoppositeiins in passage 2l. The rate of heat transfer is inversely proportional to the two-tenths power of the hydraulic diameter. It is therefore evident that by off-setting the flow in the different ananulae the two cycles are equal, whereas if one gas' stream occupies an entire annulus the two cycles would not be equal because the outside of the apparatus is nota heat transfer surface.

h eat loss from the .outside through insulation (not shown) has the same effect on temperature of nitrogen and air in both cycles, as canbe seen by study of'Flgures 4 and 4a, which 'the hydraulic diameter. For pressure drop, the

show that both of these gases contact the same portion of outside shell in both cycles.

'I'he oxygen stream flows through thev apparatus guided by one or more helically wound ns ll to impart a swirling motion to the uid, which thereby alternately passes over surface exchanging heat with air or nitrogen. This prevents any temperature stratification of the oxygen stream.

The construction shown in Figs. 8 and '7 embodies the same principles but has an additional pair of annular passages concentrically disposed inwardly of the oxygen channel I1. Thus there is an outer pair of` annular passages I5. It outside of the channel I1 and an inner pair of passages II and 3i inwardly of the channel I1. The arrangements of the inlet and outlet connections for this apparatus are shown in Figs. 7 and 8 wherein an inlet connection such as that for air designated 2I extends across the upper ends of all the annular passages but communicates only with the alternate

semi-circular sections

23, 43 at one side of the partition Il and with the intermediate sections zi, u at the other side of the partition Il. Nitrogen flows in

aiternate sections

28, 48 and intermediate sections 2l, 48. With this form there is complete baiance of the heat transfer relation of the several fluids as may be noted by examining Figs. 'I and 8 showing the relationships for both cycles. The streams of nitrogen and air, respectively, are always in passages at opposite sides of an intervening wall while the oxygen flowing through the channel I1 always has a stream of air at one side and of nitrogen at the other. .At the lower part of Fig, 7 the air is in the passage 25 outwardly of the channel I1, through which the oxygen flows and the nitrogen is in the inner passage section Il. The relation is reversed in the upper part (Fig. 7) of the apparatus where the nitrogen is in the outer passage section 28 and the air is in the inner passage section 43. When the air is caused to iiow through channels previously fllledwith nitrogen and vice versa, the respective positions of these fluids with respect to oxygen are changed as indicated in Fig. 8 but .the heat transfer relationships remain the saine.l

With supply and discharge piping connected vas'indicated in Fig. 5, all of the .valves .5l-ll are open when air flows through the passage sections 23, 25 (and Il, ,also Fig. 8) in the rst cycle and nitrogen flows through the

sections

28, 28, 46, 48 while all the valves 55-58 are closed. Conversely, in the second cycle all of the valves 55-58 are open and valves lI-SI are closed when the nitrogen is to flow through'the semi-circular sections 25', 23; (and Il, II also in Fig. 8). The relative countercurrent relation of the flow of air to nitrogen and oxygen is maintained in both cycles as the directions of flow are not changed.

In the construction diagrammatically indicated in Fig. 9 only one annular passage surrounds the channel I1 through which oxygen flows. This single annular passage, however, is divided by a number of closely spaced radial partitions 6I into any desired number of arcuate ',segments. The inlet and outlet connections to headers 62, are arranged so that one fluidv such as air flows through alternate passages I3 while the other, such as nitrogen, ilows through the intermediate passages 6l. It will be noted that the air is cooled by nitrogen flowing in intermediate channels at eitherside of its flow passages and also by the oxygen in the channel I1 at the inner duid by means of two others while providing ior transposing the relations of the treated fluid and one of the treating fluids due to the requirements of al process. Likewise, all forms make it possible to-preserve the same overall heat exchangerela.

tionship among the fluids passing through the heat exchanger in the different cycles and maintain the same pressure drop through the -various passages in each cycle of operation.

What we claim is:

l. -A heat exchanger particularly for gaseous media comprising; a cylindrical casing interiorly divided by concentric wall members extending longitudinally thereof to form a pair of adjacent annular passages; partitions extending longitudinally of said exchanger and sub-dividing each annular passage into a pair of contiguous semi-circular sections; multiple uid inlet ducts each connecting individually with a section of one passage at one side of each partition and with that section of the other passage located at the opposite side of said partition; similarly connected fluid outlet ducts; means forming a channel located adjacent the inner one vof said annular passages and concentric therewith; and inlet and outlet ducts connecting with said channel at opposite ends thereof.

2. A heat exchanger particularly for gaseous media comprising; means defining a plurality of independent parallel passages extending from rnd to end of said heat exchanger parallel to its longitudinal axis; partitions extending parallel to the longitudinal axis of said exchanger and subdividing each passage into a pair of adiacent independent sections; multiple fluid inlet ducts each connecting individually with sections of the alternate passages at one side of each parti-- tion and with sections of the adjacent passages at the opposite side of each partition; similarly connected fluid outlet ducts; means forming a channel located between two of said passages and parallel therewith; and inlet and outlet ducts connecting with said channel at opposite ends thereof.

3. A heat exchanger particularly for gaseous media comprising; means defining inner and outer pairs of concentric annular passages extending longitudinally of said heat exchanger; partitions extending longitudinally of said exchanger and sub-dividing each annular passage into a plurality of adjacent sections; multiple fluid inlet ducts each connecting individually with sections of the alternate passages at one side of each partition and with sections of the intermediate passages at the opposite side of each partition; similarly connected fluid outlet ducts; means forming a. cham,

nel located intermediate the inner and outer pairs of passages and concentric therewith; and inlet and outlet ducts connecting with said channel and opposite ends thereof.

4. A heat exchanger particularly for gaseous media comprising; means defining inner and outer pairs of concentric annular passages extending longitudinally of said exchanger; partitions extending longitudinally of said exchanger and sub-dividing each annular passage into a pair of contiguous semi-circular 6 s inlet ducts each connecting individually with scctions of the -alternate passages at one side of each partition and with sections of the intermediaiepassages at the opposite side of each partition; similarly connected fluid outlet ducts-Z means forming an annular channel located between the inner and outer pairs of es and concentric therewith; and inlet and outlet ducts connecting with said channel at opposite ends thereof.

45. A heat exchanger as recited ln claim 3 wherein the radial depth of the respective passages and channels is such that they have the same hydraulic diameter.

6. A heat exchanger as recited in claim 3 wherein the concentric circular walls forming said passages and channel are mutually spaced radially of the heat exchanger at distances pro# viding the same hydraulic diameter for all said passages and said channel.

7. A heat exchanger particularly for gaseous media comprising; a cylindrical casing interior` ly divided by concentric wall members extending longitudinally thereof to form a pair of adjacentI annular passages; partitions extendingy longitudinally of said exchanger and sub-dividing each annular passage into a pair of contiguous semi-circular sections; an inlet duct for one f and atl the other side of'said partition withfa semi-circular section of the adjacent annular passage; an inlet duct for a second fluid connecting with those sections of both said annular passages vthat .are contiguous to the sections connected with said first mentioned inlet duct; similarly connected fluid outlet ducts; means forming a channel located adjacent the inner one-of said' annular passages and concentric therewith; and

inlet and outlet ducts for circulating fluid through said channel in heat exchange relationship simultaneously with said one fluid flowing in a semi-circular section of the adjacent. annular passage and with said other fluid flowing in the contiguous semi-circular section of said same annular passage.

8. A heat exchangerv particularly for gaseous media comprising; means-defining a plurality of independent parallel passages extending from end to end of said heat exchanger parallel to its longitudinal axis; partitions extending parallel to the longitudinal axis of said exchanger and sub-dividing each passage into a pair of adjacent inde'l pendent sections; an inlet duct for one fluid connecting at one side of one partition with a section of one passage and at the other side of said partition with a section of the adjacent passage; an inlet duct for a second fluid connecting with those sections of both said passages that are contiguous to the sections connected with said first mentioned inlet duct; similarly connected fluid outlet ducts; means forming a channel located adjacent one of said passages and parallel therewith; and inlet and outlet ducts for circulating fluid through said channel in heat exchange relationship simultaneously with said one fluid flowing in a section of the adjacent passage and with said other fluid flowing in the contiguous section of the same passage.

9. A heat exchanger particularly for gaseous media. comprising; a cylindrical casing interiorly divided by concentric wall members extending longitudinally thereof to form a pair of adjacent annular passages; partitions extending longisections; multiple fluid u tudinally of said exchanger and sub-dividing 7 each annular passage into a pair of contiguous semi-circular. sections; an inlet duct for one fluid connecting at one side of one partition lwith a semi-circular section 'of one annular passage and at the other side of said partition with a semi-circular section of the adjacent annular passage; an inlet duct for a second iluid connecting with those sections of both said annular passages that are contiguous to the sections con- .neeted with said ilrst mentioned inlet duct;

similarly connected fluid outlet ducts; means forming a channel located adjacent the inner one of said annular passages and concentric therewith: and inlet and outlet ducts for circulating fluid through said channel in heat exchange relationship simultaneously with said one iiuid owing in a semi-circular section of the adjacent annular passage and with said other fluid nowing in the contiguous semi-circular section of saidsame annular passage; and a spiral dellector 4disposed in said annular channel for causing a volume of iiuid flowing through said channel at either side of its longitudinal axis to be transposed about the latter so that as said iluld volume progresses longitudinally of said exchanger it is in heat exchange relationship with thetwo fluids in the sections of the adjacent passage.

`10. A heat exchanger particularly for gaseous media having a passage extending from end to end thereof parallel to its longitudinal axis; transverse partitions in and extending from. end to end of said passage and subdividing itinto a plurality of contiguous sections for flow of iluid in parallel streams longitudinally of said exchanger; an inlet duct for one huid connecting individually with alternate sections of said passage at one end of said exchanger; an inlet duct for a second iluid connected with the intermediate sections of said passage at the opposite end A of said exchanger; similarly connected fluid outlet ducts connected to the other ends of said alternate and intermediate sections; a channel located adjacent said passage and separated therefrom by a common intervening wall; and inlet and outlet ducts connecting with said channel at opposite ends thereof for circulating a third fluid therethrough in heat exchange relationship with the rst and second fluids in the sections of said passage.

11. A heat exchanger particularly for gaseous media comprising concentric walls forming an annular passage; transverse partitions in and extending from end to end of said passage and sub-dividing it into a plurality of contiguous sections for ilow of uid longitudinally of said exchanger parallel to its axis; an inlet duct for one iluid connecting individually with alternate sectionso! saidpassageatoneendofsaidexchanger; an inlet duct for a second fluid oonnected with the intermediate sections of said passage at the opposite end of said exchanger;

Y similarly connected nuid .outlet duets connected to the other ends of said alternate and intermediate sections: means forming a channel located adjacent said annular passage and separated therefrom by a common intervening wall; and inlet and outlet ducts connecting with said channel at opposite ends thereof for circulating aVA third iluld therethroughin heat exchange relationship with the iirst and second uids flowing in the sections of said passage.

12. A heat exchanger particularly for gaseous media comprising; a cylindrical casing interiorally divided by concentric wall members extending longitudinally thereof to form a pair of forming a channel locatedadjacent the inner one .of said annular passages' and concentric therewith; inlet and outlet ducts connecting with said channel at opposite ends thereof; and deiiecting means dlspod 'across said channel and extending spirally from end to end thereof for directing the fluid in said channel in a stream. successively in contact with wall portions thereof in heat exchange relation with uid flowing both semicircular sections of adjacent 1: 1

" SVEN' HOIM.

PER HILMER. KARLSSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 621,537 Ostergren et al. Mar.' 21, 1899 1,763,012 Shipman June 10, 1930 2,057,804 Twomey f Oct. 20, 1936 2,186,077 Noyes Jan. 9, 1940 FOREIGN PATENTS Number Country Date 320,279 Great Britain Oct. 10, 1929 326,278 Great Britain Mar. 13, 1930 538,391 Great Britain July 31, 1941 615,919 France Jan. 19, 1927