US3313286A - Heat exchange apparatus - Google Patents

Description

April 11, 1967 c. D. WARE ETAL HEAT EXCHANGE APPARATUS 2 Sheets-Sheet 1 Filed Nov. 5, 1965 rimf liiimil I N VEN TORS w w WU um RD Ev R ER HA CH Y B WVMI ATTORNEYS HEAT EXCHANGE APPARATUS Filed Nov. 5, 1965 2 Sheets-Sheet 2 INVENTORS CHESTER D. WARE Y HARRY D. FOUST Mad aam ATTOR NEYS United States Patent Ofiice Patented Apr. ll, 1967 3,313,286 HEAT EXCHANGE APlARATUS Chester D. Ware, La Crosse, Wis, and Harry B. Faust, Dakota, Minn, assiguors to The Trane Company, La Crosse, Wis, a corporation of Wisconsin Filed Nov. 5, 1965, Ser. No. 506,596 7 Claims. (Cl. 126-110) This invention relates to heat exchange apparatus of the type comprising a combined fan and extended heat exchange surface. More particularly, this invention is directed to a compact, warm air furnace having an elongated combustion chamber-heat exchange member over Which a stream of air is directed.

The essence of this invention lies in the provision of a fan-heat exchanger combination which achieves maximum utilization of the radiation and convection efi'ects available from a hot aseous stream. This general objective is accomplished by two means:

1) By the particular construction of the flow passages for the air to be heated and the combustion gases, which permits these fluid streams to be directed in paths providing for good indirect heat transfer and producing minimum resistance to flow.

(2) By constructing and interrelating the air circulating fan, the heat exchanger, and the furnace housing in such a way as to r 'ze a significant reduction in mate rial requirements while at the same time obtainin optimum heat transfer.

By virtue of these two basic design criteria We have succeeded in producing an extremely efficient and compact furnace of much higher capacity than furnaces of comparable size now available.

The specific objects of this invention as reflected in the particular structural means utilized to achieve the above two design goals are as follows:

The construction of a furnace wherein an outer casing surrounds a combustion chamber so as to form an annular passage for the flow of air to be heated, and wherein the blades of the fan for circulating the air extend into the annular passage, the outer casing thus serving as a housing for the fan.

The construction of a furnace as aforesaid and further including a base connected to said outer casing by means of a slip joint whereby said casing may be rotated about said base so as to permit the selection of any angular orientation for the flue gas outlet extending from said combustion chamber through said casing.

The provision of a fan-heat exchanger combination including an outer casing enclosing said heat exchanger so as to form an annular passage for the flow of a fluid to be heated wherein the fan has a first set of blades for forcing a fluid directly into said annular passage and a second set of blades adapted to force a fluid over one end of said heat exchanger and then into said annular passage.

The construction of heat exchange apparatus having a generally tubular heat exchange member and a surrounding casing arranged with an annular fluid flow passage therebetween, and including scoop means disposed in said annular passage so as to direct a portion of the fluid discharging therefrom into a hollow baffle element extending into said tubular heat exchange member in spaced relation thereto.

The provision of heat exchange apparatus of the type described in the aforesaid objective wherein a voluteshaped, circumferential groove is formed in said hollow baflle element to serve as a collection and discharge passage for a heating fluid flowing out of said tubular heat exchange member.

The provision of a furnace having a combustion chamber spaced and supported from an enclosing casing solely by means of an air and fuel inlet conduit and a flue gas exhaust conduit extending between said combustion chamber and said casing.

These and other objects and advantages of the invention Will become readily apparent as the following description is read in conjunction with the accompanying drawin s, of which:

FIGURE 1 is a front elevational view, partly cut-away, of a furnace embodying the improved features of our invention;

FIGURE 2 is a cross-sectional view of the airfoil shaped, combustion air and fuel inlet taken along line 22 of FIGURE 1;

FIGURE 3 is a top view of the furnace of FIGURE 1;

FIGURE 4 is a view of the air diverting scoop showing the side opposite from that illustrated in FIGURE 6;

FIGURE 5 is a perspective view of the fan of FIG- URE l; and

FIGURE 6 is a vertical cross-section view of the top portion of the furnace taken along line 6-6 of FIG- URE 3.

With reference to FIGURE 1, our improved furnace has as its basic components a combined combustion chamber-heat exchan er 1 and an air circulating fan 2. Enclosing combustion chamber 1 in spaced relation thereto is outer casing 4, which forms with combustion chamber 1 an elongated annular passageway 63 for the flow of air to be heated. it will be noted that the side walls of outer casing 4 diverge outwardly at the top of the furnace. Thus an air discharge passageway of gradually increasing cross-section is provided at the outlet of annular space to affect pressure regain of the leaving air stream. Recovery of dynamic pressure is also enhanced by the use of a plurality of straightening vanes 5 in the exit portion of annular heat exchange passage Combustion chamber 1 is supported from casing 4 solely by means of combined combustion air and fuel gas inlet conduit 8 and flue gas outlet conduit iii. Conduits 8 and 1'!) are welded over openings in the side wall of chamber 1. Venturi-shaped burner 12 passes through inlet conduit 3 into combustion chamber 1, and is connected at its outer end to fuel gas pipe 14. The flow of fuel gas through pipe 14 is regulated by a conventional assembly of controls including a main automatic gas valve l6, pressure regulator 18 and pilot safety shut-o valve These controls are located within cover 22 which is provided with exhaust stack 26 and louvered draft diverter openings 24 in communication with flue outlet 16-. Cover 22 thus serves as both a control housing and draft diverter. The open bottom end of cover 22 provides an inlet opening for both primary and secondary combustion air. Primary air is induced into venturi-shaped burner 12 by the flow of fuel gas through pipe 14 in the conventional manner, and secondary air flows upwardly through the bottom end of cover 22 and inlet conduit 8 in the portion thereof surrounding burner 12. While a gas burner arrangement has been shown, it is obvious that our improved furnace may be equally well adapted to the burning of oil.

It is highly desirable to minimize the obstructions to airflow in annular passage 6 in order to limit as much as possible the pressure loss incurred by the fan air. This has been accomplished by directing both the fuel and combustion air through a single conduit 8, as opposed to using separate pipes for each of these fluid streams, and by constructing conduit 8 with an airfoil cross-section. The configuration of conduit 8 is more clearly shown in FIGURE 2. The chord of the airfoil section of conduit 8 is oriented to be in alignment with the absolute velocity vector of the air, which leaves fan 2 at an angle of approximately 45 to the vertical axis of the fan-heat exchange unit. An angular swirl is thus imparted to the air. Varies 5 serve to substantially reduce the swirling motion of the air and straighten it out as it leaves the top of annular passage 6.

It is significant to note at this point that combustion chamber 1 is preferably of cylindrical shape and has a series of generally laterally extending corrugations 28 superimposed thereon. corrugations 28 provide additional heat transfer surface in a compact shape and also serve to induce turbulence in the swirling fan air, thus keeping it in intimate heat transfer relationship with the outer surface of combustion chamber 1. The corrugations additionally serve to create a black-body condition in that they serve to trap radiant energy emanating from within the combustion chamber. This heat energy is in turn given up to the air flowing through annular passage 6. Furthermore, the arrangement whereby chamher 1 is supported solely by laterally extending conduits 8 and 10 permits corrugated chamber 1 to thermally expand and contract in a vertical direction with a bellowstype action. and contraction of cylindrical, corrugated, combustion chamber 1 greatly minimizes the noise and metal fatigue normally associated with the planar metal walls of hot air furnaces.

Referring now to FIGURES 1 and 5 it will be seen that fan 2 is comprised of an annular wheel 39 from which a first set of blades 32 extend outwards adjacent the lowe extremity of annular passage 6. A second set of blades 34 extend radially inwards through the hollow interior portion of wheel to hub 36. The entire fan assembly 2 including wheel portion 30, hub 36 and blades 32 and 34 is preferably cast as an integral unit. Fan 2 is driven by motor 40, the rotor shaft of which extends into hub 36. As may be clearly seen in FIGURE 1, a portion of fan blades 32 and 34 extend upwardly around the bottom of combustion chamber 1 into annular space 6. As a result of this arrangement the lower part of easing 4 opposite the bottom of combustion chamber 1 serves as a housing for part of fan 2. Thus casing 4 need not be extended as far downwardly to form a separate housing for fan 2, and the overall height of the unit is reduced. The portion 31 of wheel 36 extending axially into annular passage 6, and the axially extending tip portions of blades 34 serve to turn the air discharging radially from blades 34 around the bottom 29 of combustion chamber 1 and upwardly into passage 6. semicircular bafiies 42 are secured to the bottom of fan wheel portion 30 as shown in FIGURE 1 in order to provide a smooth inlet for air flowing upwardly through blades 32 and 34. The flow of air upwardly around both sides of baflies 42 is indicated by arrows in FIGURE 1.

Outer casing 4 rests on rectangular base 46 and is connected thereto by means of a slip joint. For this purpose lip 48 is provided at the bottom of outer casing 4 to slide over circular neck 44 at the top of base 46. The slip-joint connection between outer casing 4 and base 46 permits the selection of any angular position for flue gas stack 26 by rotating casing 4 about its base. This feature is particularly desirable in limited space applications. The bottom of base 46 is open to provide an inlet for the flow of air to be heated. The furnace is placed over an aperture in the floor of a utility closet or similar site, and fan 2 draws air up through the door aperture and the bottom of base 46 into annular passage 6 of the furnace. Alternatively base 46 could be formed with a solid bottom, and louvered openings could be provided in the side walls of base 46 for the intake of air. The customary air filters (not shown) are positioned in base 46.

Combustion chamber 1 is sealed at its bottom end by a closing wall 2 adjacent fan 2. Suspended from the upper end of combustion chamber 1 in sealing relation thereto is a radiation and convection improving baffle element 5%. Bafiie 5% is in the form of a hollow cylinder of smaller diameter than chamber 1, and serves several important purposes. By being positioned concentrically This is important in that the free expansion within combustion chamber 1, battle element 50 cooperates therewith to perform its basic function of forming an annular passageway 52 for the convection flow of combustion gases. In order to evenly distribute the rising combustion gases into annular passage 52 on all sides of bafiie element 59 with the creation of minimum turbulence, the bottom 54 thereof is given a concave shape. The concave shape of bottom surface 54 also allows relatively free thermal expansion and contraction of this surface without attendant noise and metal fatigue. he upper end of baflde element 56 is provided with a voluteshaped groove 56, the upper, inclined edge 62 of which is welded about its periphery to the top edge of combustion chamber 1. The annular space 53 between groove 56 and the surrounding walls of combustion chamber 1 serves as a collection and discharge zone for combustion gases. An opening in the upper end of the wall of combustion chamber 1 communicates space 58 with flue gas outlet conduit 10.

The volute shape of combustion gas discharge zone 58 induces a velocity pressure at the relatively small crosssectional area thereof which is substantially equal to the velocity pressure at the large cross-sectional exit area adjacent outlet conduit 1%. By virtue of this arrangement a substantially equal pressure drop and thus a substantially equal combustion gas flow is realized throughout annular passage 52 about the entire periphery of baflle element 50. If groove 56 were not given a volute shape, discharge zone 58 would be of uniform cross-section and a greater velocity pressure would develop in the portion thereof adjacent outlet conduit 19. This would induce a disproportionately greater flow of combustion gas upwards through the section of annular passage 52 immediately below outlet conduit 10. The smaller flow of combustion gas through the opposite side of annular passage 52 remote from outlet conduit 10 would result in reduced heat transfer to the air flowing through the adjacent portion of annular passage 6. Thus the disadvantages of unequal combustion gas flow and unequal heating of the air in passage 6 are obviated by providing a combustion gas discharge passage 58 of volute crosssection.

As a further device for recovering the maximum amount of heat energy from the products of combustion, we provide means for diverting a portion of the fan air leaving annular passage 6 downwardly into the interior of hollow baflle element 50. As will be more clearly pointed out below in explaining the operation of our improved heat exchange apparatus, bafile 50 is heated by the hot combustion gases and in turn gives up some of the heat to that portion of the fan air which is diverted against its interior walls. Various means may be employed for directing a portion of the air from passage-,

way 6 into baffle element 50. The preferred arrangement is shown in FIGURES 1, 3, 4, and 6, and comprises a sheet metal scoop 60 abutting against the inside wall of outer casing 4 and arcing inwardly and downwardly into the interior of hollow baflle element 50. As may best be seen in FIGURES 1 and 6, scoop 60 has a curved upper portion 64 resting at its outer extremity against the inside surface of outer casing 4. Horizontally extending edges 66 of sidewalls 70 rest on the upper edge 62 of halide element 50 and serve to support scoop 60 in the position shown. Upper portion 64 curves over the top of upper edge 62 and merges with a downwardly extending wall 72. Wall 72 is conically shaped and inclines backwardly under volute-shaped groove 56 toward the inner surface of cylindrical baffle element 50, as is best shown in FIGURES 3, 4 and 6. Curved bottom edge 68 of wall 72 is positioned very close to the inner wall of bafile element 50 so as to form therewith a narrow, annular slot 74 for the discharge of air (see FIGURE 3). FIGURE 4 shows scoop 60 as viewed from the left side of FIGURE 1, i.e. the view is of the back side of the scoop, whereas FIGURE 6 shows the front side of the scoop. With reference to these two views, it will be seen that side walls 79 are twisted so as to conform to the inner cylindrical surface of baffle element 59 in sealing contact therewith. Thus a portion of the air rising upwardly in annular passage 6 is intercepted by upper curved portion 64 of scoop of and is directed downwardly over the back side of conical wall 72 as is indicated by the flow arrows in FIGURE 4. The conical shape of wall 72 causes the air to discharge from its bottom edge 68 against the inner surface of baffle element 50 in a downwardly swirling pattern. Thus the air diverted by scoop of swirls downwardly over bafile 50 in good heat exchange relation therewith and is further heated before rising upwardly to discharge from the top of the furnace.

As may clearly be seen in FIGURE 3, scoop on extends only a part of the way around the top of annular passage 5. For purposes of illustration, scoop 60 is shown as a segment extending90 around the circumference of casing 4. Scoop 6% may be made to cover a greater or lesser portion of the top of passage 6 depending upon the amount of air which one wishes to divert into baflie i) and the degree of pressure drop in the leaving fan air which can be tolerated. Obviously, if scoop 60 extended all of the way around the top of annular space 6, all of the leaving air would be directed into baffle 56 and the leaving air stream would undergo a considerable pressure drop. By extending scoop 6-0 against outer casing 4, all of the air flowing upwardly through passage 6 under the scoop, including the air flowing along the inner wall of casing 4, is caused to flow into bafiie element 59. This is particularly desirable since it is this outer layer of air along casing 4 farthest away from combustion chamber 1 which is heated the least and thus needs to be further warmed by heat exchange with the hot surface of hollow baffle element 50. An alternative way of directing some of the air from passage 6 into baffle 53 would be to suspend a scoop from the top of combustion chamber 1 in such a way that the outer end thereof would terminate in annular passage 6 between combustion chamber 1 and casing 4 rather than extending all of the way out to casing 4. Such a scoop would extend all of the way around the top of annular passage 6t) so that a portion of the rising air would be diverted into bafile 58 while the remainder would fiow upwardly between the outer edge of the scoop and the inside of casing 4. This scoop arrangement would not produce too severe a pressure drop in the air stream. However, the foregoing advantage of directing some of the relatively cooler air along the inside wall of casing 4 into hot bafile 59 would be lost.

In operation, a stream of fuel gas and primary air passes into the lower end of combustion chamber 1 through burner nozzle 12 and is ignited in the presence of secondary air induced through conduit 8. The gaseous products of combustion rise upwardly and impinge against the bottom concave surface 54 of baffle element 50, whereby they are diverted evenly into annular space 52. The combustion gases then pass upwardly through annular space 52 into collection zone 53, from which they flow out through conduit to exhaust stack 26. Extremely hot combustion gases in the lower part of combustion chamber 1 lose heat principally by radiation to bot-tom wall 29, to the side walls of chamber 1 and to concave wall 54. The somewhat cooler but still very hot combustion products in annular passage 52 transfer heat to bafiie element 50 and the upper walls of combustion chamber 1 by radiation and forced convection, the latter mode being the dominant regime. Bafile element 50 radiates heat outwardly to the relatively cooler walls of combustion chamber 1 and also loses heat by forced convention to the fan-air directed into its interior by scoop 60.

Air to be heated is forced into annular heat exchange passage 6 by fan 2. Fan blades 32 supply the major ii portion of the air, which flows directly into passage 6 in an axial direction and mixes just downstream of the fan wheel with the smaller stream of air issuing from supplementary blades 34. Blades 34 serve several purposes. Their proximity to combustion chamber 1 causes them to be heated by radiation from the bottom 29 of the combustion chamber. They thus serve as an additional heat transfer surface, giving up this heat by convection to the air flowing over them. The air discharging from blades 34 is further heated by convection as it flows in a substantially radial direction over the extremely hot bottom wall 29 of combustion chamber 1. Blades 34 also function to draw a cooling stream of air over and through motor 40 and the fan assembly. This prevents overheating of the motor and permits the use of low temperature materials such as aluminum in constructing the fan. The air leaving fan 2 swirls upwardly in a helical pattern through annular passage 6 over the corrugated wall of combustion chamber 1. The hot outer surface of chamber 1 thus heats the air by convection. Heat is also transferred to the air from the inner surface of outer casing 4, this surface being heated by radiation from the walls of combustion chamber 1. That portion of the air which is diverted by scoop 6% receives additional heat as it swirls against the hot inner surface of halide element 543 before exiting from the top of the furnace.

On the basis of the foregoing discussion it will be clear that all surfaces of our improved fan-heat exchanger assembly are effectively utilized for the transfer or" heat. The manner in which fan 2 is arranged to embrace the bottom of the combustion chamber permits all of the metal which is normally used only as fan structure to serve as heat exchange surface as well; and by extending the blades of fan 2 up into annular passage 6, outer casing 4 advantageously becomes a fan housing in addition to being a heat exchange surface and support means for the combustion chamber. These and the other unique features discussed above cooperate in the formation of a very efficient furnace having exceptional capacity for its size. Although our improved heat exchange apparatus has been described as a hot air furnace, those skilled in the art will readily appreciate the adaptability of our novel structural features to other types of heat transfer ap lications. Thus any gaseous stream could be circulated by fan 2, and fluids other than combustion gases could be directed through chamber 1 via conduits 8 and It).

We do not intend to limit our invention to the particular embodiment shown and described, which is illustrative only. It is contemplated that changes may be made without departing from the spirit and scope of the invention as defined by the following claims.

We claim:

1. A furnace comprising: an elongated casing; a tubular heat exchange member disposed within said casing and spaced inwardly therefrom so as to form an annular passage for the fiow of air to be heated, said heat exchange member being provided with a fuel and combustion air inlet and a flue gas outlet; a fan for circulating air to be heated through said annular passage; a cylindrical baflie element extending into said tubular heat exchange member and sealingly connected thereto at one end, said bathe element being of smaller crosssection than said tubular heat exchange member whereby an annular passage for the how of combustion gases is formed between said baffle element and said heat exchange member; a volute-shaped, circumferential groove in said bafile element adjacent said one end, said groove and the surrounding portion of said tubular heat exchange member serving to define a collection and discharge passage for combustion gases, said discharge passage increasing in cross-sectional area in the portions thereof closest to said flue gas outlet.

2. A furnace comprising: a cylindrical combustion chamber having a combined fuel and combustion air inlet opening and a line gas outlet opening; generally laterally disposed corrugations extending continuously about the entire periphery of said combustion chamber; an outer casing surrounding said combustion chamber and spaced outwardly therefrom so as to form an annular space for the flow of air to be heated; a first conduit extending through said annular space and connecting said inlet opening with a first opening in said outer casing; a second conduit extending through said annular space and connecting said outlet opening with a second opening in said outer casing; said first and second conduits constituting the soie means for supporting said combustion chamber within said outer casing, whereby said corrugated combustion chamber may freely expand and contract in response to changes in temperature.

3. Heat exchange apparatus comprising: an elongated casing; a generally tubular heat exchange member concentrically positioned within said casing and spaced inwardly therefrom so as to form an annular passageway for the flow of a fluid stream, said tubular heat exchange member being sealed at one end by a closing wall; a fan located within said casing adjacent said closing wall and having an axis of rotation coextensive with the longitudinal axis of said tubular heat exchange member, said fan including a first of axial flow blades positioned adjacent said annular passageway, and a second set of blades lyin in planes substantially parallel to the longitudinal axis of said tubular heat exchange member and extending outwardly from said axis of rotation along said closing wall, whereby said first set of blades will direct a fluid axially into said annular passageway and said second set of blades will direct a fluid generally radially outwards over the surface of said closing wall towards said annular passageway.

4. Heat exchange apparatus as recited in claim 3, wherein said fan comprises an annular wheel, said first set of blades extending outwards from the outside surface of said annular wheel and lying in their entirety outside of said wheel, and said second set of blades extending radially inwards from the inside surface of said annular wheel, whereby said second set of blades forces a fluid through the inside of said annular wheel and over said closing Wall.

5. Heat exchange apparatus as defined in claim 3, wherein each of said second set of blades has a tip portion extending axially into said annular passageway.

6. Heat exchange apparatus comprising: an elongated casing; a tubular heat exchange member disposed concentn'cally within said casing and spaced inwardly therefrom so as to form an annular passage for the flow of a fluid stream to be heated; a fan for circulating said fluid stream through said annular passage, said fan being disposed adjacent one end of said heat exchange memher; a hollow baflie element extending into said heat exchange member from the opposite end thereof, and spaced inwardly therefrom; means for diverting a portion of the heated fluid stream discharging from said annular passage into said hollow baffie element, said means comprising a scoop extending a substantial distance around said annular passage in sealing relationship with the inside of said casing and having a portion thereof extending towards the interior of said hollow baffle element; an inlet for conducting a heating medium into said heat exchange member in proximity to said one end; and an outlet for discharging heating medium from said heat exchange member in proximity to said opposite end.

7. A furnace comprising: a combustion chamber having a fuel and combustion air inlet and a fiue gas outlet, said combustion chamber being sealed at one end by a closing wall; an outer casing enclosing said combustion chamber and spaced therefrom so as to form an annular passageway for the flow of air to be heated; a fan positioned within said outer casing with its axis of rotation coextensive with the longitudinal axis of said casing, said fan including a plurality of blades lying in planes generally parallel to the longitudinal axis of said casing and extending substantially radially outwardly along said closing wall in closely spaced, heat transfer relation thereto; and turning means to direct the air issuing from said blades around said one end of said combustion chamber and into said annular passageway in an axial direction, said turning means comprising an annular wheel secured to the outer extremity of said blades, an axially extending tip portion of each of said blades, and an axially extending wall portion of said wheel against which said tip portions abut.

References tlited by the Examiner UNITED STATES PATENTS 150,603 5/1874 Patric 126-106 2,162,084 6/1939 Hoffman 126-110 X 2,574,024 11/ 1951 Elliott 126106 2,588,352 3/1952 Budlane 126-110 2,600,020 6/1952 Pietsch 126-110 2,704,062 3/1955 Beyerman l26l10 X 2,715,975 9/1955 Johnston 126-110 2,808,047 10/1957 Jaye et al.' 126-1 10 X 3,125,089 3/1964 Taylor 1261 10 FOREIGN PATENTS 1,061,162 11/1953 France.

769,776 3/ 1957 Great Britain.

JAMES W. WESTHAV-ER, Primary Examiner.

Claims (1)

1. 6. HEAT EXCHANGE APPARATUS COMPRISING: AN ELONGATED CASING: A TUBULAR HEAT EXCHANGE MEMBER DISPOSED CONCENTRICALLY WITHIN SAID CASING AND SPACED INWARDLY THEREFROM SO AS TO FORM AN ANNULAR PASSAGE FOR THE FLOW OF A FLUID STREAM TO BE HEATED; A FAN FOR CIRCULATING SAID FLUID STREAM THROUGH SAID ANNULAR PASSAGE, SAID FAN BEING DISPOSED ADJACENT ONE END OF SAID HEAT EXCHANGE MEMBER; A HOLLOW BAFFLE ELEMENT EXTENDING INTO SAID HEAT EXCHANGE MEMBER FROM THE OPPOSITE END THEREOF, AND SPACED INWARDLY THEREFROM; MEANS FOR DIVERTING A PORTION OF THE HEATED FLUID STREAM DISCHARGING FROM SAID ANNULAR PASSAGE INTO SAID HOLLOW BAFFLE ELEMENT, SAID MEANS COMPRISING A SCOOP EXTENDING A SUBSTANTIAL DISTANCE AROUND SAID ANNULAR PASSAGE IN SEALING RELATIONSHIP WITH THE INSIDE OF SAID CASING AND HAVING A PORTION THEREOF EXTENDING TOWARDS THE INTERIOR OF SAID HOLLOW BAFFLE ELEMENT; AN INLET FOR CONDUCTING A HEATING MEDIUM INTO SAID HEAT EXCHANGE MEMBER IN PROXIMITY TO SAID ONE END; AND AN OUTLET FOR DISCHARGING HEATING MEDIUM FROM SAID HEAT EXCHANGE MEMBER IN PROXIMITY TO SAID OPPOSITE END.

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