CA1163987A

CA1163987A - Tertiary heat exchanger

Info

Publication number: CA1163987A
Application number: CA000378312A
Authority: CA
Inventors: Ingemar Persson; Olov Eklind
Original assignee: Parca Norrahammar AB
Current assignee: Parca Norrahammar AB
Priority date: 1980-05-27
Filing date: 1981-05-26
Publication date: 1984-03-20
Also published as: SE421934B; SE8003949L

Abstract

ABSTRACT OF THE DISCLOSURE

A tertiary heat exchanger having three sets of adjacent ducting, two stacked within the third, all of which carrying heat exchange mediums so that the heat carried by one medium in any set of a ducting is efficiently transferred to the other two. Two of the three sets of ducting are tubing and this tubing is helically coiled in a container within the third set of ducting. The two sets of tubing are in alternating layers and the fluid flow of the heat exchange mediums are in opposite directions in each adjacent layer of the tubing. Outlet channels are provided at various points along the helical path of a ducting so as to alter the effective length of a ducting.

Description

~ 1 ~39~7 BACKGROUND OF THE IN~ENTION
The present invention relates to heat, exchangers, and more particularly to heat exchaneers having first and second spiral tube arrangements conducting ~irst and second heat exchange mediums, respectively, with a third heat exchange medium conducted through a ~luralit,y of ducts formed between, and surroundin~, the tube spirals.

Many ~ields o r use exist for t,ertiary heat ex-changers: radiator exchangers, hot wat,er exchangers in a heat pump, district heating systems or boiler stations, heat exchangers in water storage t,anks, ground heat exchangers, etc.

Typically heating stations with heat pumps and/or district heating constitute an area where tertiary heat exchangers are required. In such stations, there is a flow of heat exchange medium into a first side of the exchanger, which is supplied wit,h heat from a heat pump, a solar ab-sorbator, or the like. A second side ol' ~,he exchanger includes, on the one hand, a charginfr~ circuit, of a st,orafre tank for warm water, and on the other hand, a radiator circuit. Previously known heat exchangers ofthe tertiary type used in this field comprised separat,e st,acks o~ t,ube spirals, each one conduct,infr~ a heat, exchanfr,e medium and positioned in a tank. Between the two st,acks of tube spirals, a third heat exchange medium served as a heat exchanging agent.

. _ ~

~ 1 63987 A primary purpose of the invention is to pro-' vide a heat exchanger in which the effective len~ths of ~'low o~' t~le ~wo heat exchange Ille~iulrls in ~he prilllcll~y and secondarycircuits can be made different, so that it is possible to optimize the quantity of exchanged heat at certain pressure drops and temperature levels. In practice, this can be attainecl in such a way that the media are conducted in spiral tubes andducts from the center of the vessel to the periphery, or between an input position and an output position a bit -~rom t,he center endthe periphery. The effective length of the spiral duct can thereby be more or less shortened in-dependent of the routes of flow of the other fluids, and can be located arbitrarily along the routes of these ones.

SUMr~ARY OF THE INVENTION

These and other purposes may be realized by the present invention in which a tertiary heat exchanger is provided with three sets of ad,j(lcerll; ducting~ two stacked within the third, all of which carrying heat exchange mediums therethrough, so that heat carried by one medium in any set of the ducting is efficiently trans~erred to the others. The heat exchanger is provided with primary and secondary tubing or ducting which is helically coiled or wound in a spiral fashion in a cylindrical tank. The primary and secondary tubing is stacked in alternating layers, and pressed together by the tank end walls.
Jacketing the primary and secondary stacked layers is the tertiary ducting which permits a third heat exchange medium carried within to be placed in intimate contact with the primary and secondary tubing. In this way, the tertiary ~ ~ ~3987 he~t exchanr;cr o f l:he proscr~ vellt::i on pr(:)v~i(3cs sub-stantially increased e:f~icierlcy ~>ver ~.ertiary heat exchangers heretofore known in the prior art.

BRIEF DESCRIPTION ori' Tl[E DRAWINGS

In order to achieve the aforesaid purpose, the invention has been given the characterizing features de-fined in the attached claims. An embodiment of the in-vention is described as ~ollows, with re~erence to the accompanying drawings, in which:

Figure 1 shows a vertical cross-section through a hcat cxch;lrl~or accordinr to the prcsent inventi.on; and Figure 2 illustrates the view taken along section line 2-2 of Figure 1, showing a sectional view of the heat exchanger tank and the corresponding winding pattern for the tube spirals enclosed within the heat exchanger.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals represent identical forcorresponding parts through-out the views, Figure 1 depicts a cross-sectional view of the heat exchanger of the present invention, taken along section line 1-1 of Figure 2, in which a tank or cistern 1 includes bottom end wall 2 and top end wall 3. The tank, which is normally closed, contains a pressurized heat ex-change medium, for example water wi~h ~.he pressure en-su:r-irlg t;~lat circulatiorl to dlstanl. polnts of use is achieved, as for example to radiators or the like. Located within the vessel is a heat exchanger battery 4 including a ~ 1 ~3987 first (primary~ portion or circuit provided with an inlet manifold pipe 5 and an outlet manifold pipe 6, and a second (secondary) portion or circuit provided with inlet and outlet manifold pipes 7 and 8, respectively. Carried within the primary and secondary circuits are primary and secondary heat exchange media, respectively. The primary and secondary circuits of the battery each comprise several layers of wound tubing 9, 10 which enclose and conduct respective heat exchange media from the inlet, to the outlet, manifold pipes, respectively.

The increased efficiency of the heat exchanger of the present invention is a direct consequence of the manner of winding the tubing used in the battery. The primary and secondary circuits,comprising the tubes 9, 10, respectively, are stacked alternately one on the other in a vertical extent in such a manner that every second tube in the vertical extent of the winding belongs to one circuit, and the other tube to the o~her circuit. The tubes 9 and 10 are pressed against each other in the stack, the end walls of the tank compressing the windings in an axial direction.
Contact between the tubes, which preferably are metal, causes heat; conduc~ rl Irom t.ube 9 t.o t;ube 10, the heat transport by contact with the surrounding radiator water effecting a double-exchange between the tubes 9 and 10.
The coiled tubing 9 and 10 are in contact throughout their entire length from the inlet manifold pipe to the outlet manifold pipe, helically disposed duct 13 being provided about the tubing within tank 1, to thereby enclose or jacket the entire stack of layered tubing 9, 10, 9, 10...

The invent.ion contemplates that the heat exchange ~ medium used in the bat.tery primary circuit will b~ ~6 and the second circuit medium will be tap water. Thus, _ _ .. . . . . . .

1 1 639~7 for example, radiator water coming from a pump is con-ducted into the tank through the bottom thereof by pipe 11.
The water, heated by the tubing 9 which encloses the freon, is made to pass through the battery outwardly to the outlet 5 pipe 12 located in the circumference of the tank shell. In addition, tap water is sent through the inlet manifold pipe 7, into theb~lt;ery secondary circuit through the tubing 10, and out through the manifold pipe 8 to a point o~ use. The tap water carried by tubing 10 is heated by conduction, that is, the heat from tubing 9 being trans-ferred to tubing 10. To enhance the heat transfer process, tubings 9 and 10 are arranged so that the freon in tubing 9 flows in a direction counter to the direction of flow of the water in tubing 10. The pressurized water conducted into tank 1 through pipe 11 is forced through ducting 13 between tubing 9 and 10, and passes through the ducting, adjacent to, and along the entire length of, the tubing 9 and 10. This, of course, assumes that inlet 11 and outlet 12 are located in the center, and periphery, of the tank 1, respectively.

Owing to the compression of the stacked winding, and the abutment of the end walls t~o the outermost layers, the necessity of a ba~fle between the turns is eliminated thereby enabling a tremendous savings. The compression of the stacked windings is further advantageous inasmuch as every turn of the winding presses against an adjacent turn, and the outermost layers press against the end walls so that the turns support each other and are thereby kept in place without any assisting means. The battery, and thus the heat exchanger, then attain a compact design which per~its a simple installation of the exchanger.

I ~ ~3~87 From an economic standpoint,, it is advantageous to heat each one of the primary and secondary circuits to a desired end temperature directly in the heat, exchanger, inasmuch as losses will occur when the temperature first is increased in a circuit; to a ceri,ain high value and a~fter that decreased by mixing. Such an advantap:e is obtained by tapping t,he radiator water frorn duc1, 13 within the battery. The radiator water is therefore forced through spiral duct 13 in a direction counter to the direction ln of flow of the heat transfer medium in tube 9 so that the route of flow begins at the inlel; 11 and proceeds in a spiralling fashion through duct 13 to a collecting duct 14, where the duct 13 ends, and the manifold pipe 15 conducts the water out Or the vessel to a receiving consumer station. The collecting duct 14 intersects duct 13 and thus effectively shortens duct 13 in relation to the tubing 9, 10. Duct 13 ex~,ends a bit beyond collecting duct 14, but that portion does not take part in the flow. By shortening duct 13 in this way, an ad-vantage may be obt,ained when it is desirable ~,o controlthe heat imparted to the primary and secondary circuits, i.e. when there is a ~leed to heat the tap water to a higher temperature than t,he radiator water. By using this first portion of the tertiary circuit (duct 13) only for heating the radiator water, it is possible to reach a higher temperature than when -the primary and secondary circuits are employed all the way along the tertiary circuit. The tapping off through pipe 15 from collecting duct 14 brings radiator water having the proper end 3o temperature directly in the exchanger, and mixing is therefore rarely required.

In a variation of the present in~ention, the circuit containing the radiator water includes an inlet 16 connected to an inlet duct 17, where a portion of duct 13 1 ~ 63987 , is circumvented. By such an arrangement, it is possible to provide an undercooling of the primary circuit, as~
for example, when it comprises a condensor of a heat pump. In the end portion of the primary circuit, where the main part o~ the ~reon already has condensed but still contains an amount oI heat, some heat exchange occurs between the rreon and the tap water which, prior to the heat exchange, has a lower temperature. In the hottest portiorl oL ~he primary circui~, tl~o ~leat rrc)m the freor is transrerred to the tap water with su~ficiently high temperature to insure that the radiator water has a proper end temperature.

Obviously, many modifications and variations Or t:he presellt inverltion are possible in light of the above teachings. For example, while the tap water in the above described embodiments may be the tertiary medium, and the radiator water the secondary medium, other media can also be utilized in the circuits. It is therefore understood that, within the scope of the appended claims, the in-vention may be practiced otherwise specifically describedherein.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A tertiary heat exchanger, comprising:
a container including inlet and outlet means;
a first fluid conducted into said centainer through one of said inlet means;
first means helically disposed within said container, and forming a passageway extending from said one inlet means outward to one outlet means, for conducting said first fluid out of said container;
second means for conducting a second fluid through said container;
third means for conducting a third fluid through said container;
at least one of said first, second or third conducting means having a length which is alterable;
one of said first, second or third fluids being heated, and a substantial portion of said second and third conducting means being housed within said first conducting means so that heat from said one fluid is imparted to the remaining fluids by conduction when said fluids are caused to flow through their respective conducting means.

2. The tertiary heat exchanger as claimed in claim 1 wherein said second and third conducting means are coiled within said first conducting means, and said container includes means for holding said second conducting means in contact with said third conducting means, whereby maximum heat transfer between said conducting means is facilitated.

3. The tertiary heat exchanger as claimed in claim 2 wherein each of said second and third conducting means comprise a layered stack wherein each turn of the respective coil defines one layer, the direction of flow of fluid in said second conducting means is opposite to the direction of flow of fluid in said third conducting means, and said holding means defines surface means, located above and below said second and third conducting means, for pressing said second conducting means against said third conducting means throughout their entire length.

4. The tertiary heat exchanger as claimed in claim 3 wherein said second and third coiled conducting means form a single stack having a plurality of layers, wherein every n th layer comprises one of said second or third conducting means, and every n+l th layer comprises the other of said second or third conducting means.

5. The tertiary heat exchanger as defined in claim 3 wherein the layered stack formed by said second conducting means comprises, with the layered stack formed by said third conducting means, a single layered stack wherein successive layers of said first stack alternate with successive layers of said second stack.

6. The tertiary heat exchanger as defined in claim 3 wherein said single layered stack defines, in vertical cross-section, a plurality of vertically extending rows, each said row compressed between said surfaces means, and said first conducting means defines, in vertical cross-section, a plurality of compartments, each compartment being configured to jacket a single row.

7. The tertiary heat exchanger as defined in claim 6 wherein at least one of said fluids is liquid and conducted through said container under pressure, and at least one of said second or third fluids is heated.

8. The tertiary heat exchanger of claim 1 wherein said container outlet means comprises two outlets associated with said first conducting means including means for alterately rerouting said first fluid through one of said two outlets so that said first fluid can be conducted out of said container

9. The tertiary heat exchanger of claim 8 wherein said container comprises means for holding said second conducting means in contact with said third conducting means, one of said two outlets being located in a side wall of said container, and said one of said container inlet means being located at the center of one of said holding means, whereby the distance over which said first fluid is conducted is maximized.

10. The tertiary heat exchanger of claim 9 wherein the other of said two outlets is disposed in the holding means at a first location between said one of said inlet means and said one of said two outlets, and said rerouting means comprises means for intersecting said first conducting means along the length thereof at said first location, whereby when said rerouting means becomes operative, said other of said two outlets are opened causing said first fluid to flow out of said container through said other outlet and thereby altering, by shortening, the effective length of said first conducting means.

11. The tertiary heat exchanger of claim 1 wherein said container includes inlet means for each of said second and said third conducting means, one of said second and third conducting means comprising two outlets, and further comprising, means, associated with said outlets, for alternately rerouting the fluid in said one of said conduction means through an appropriate one of said outlets so that only one outlet at a time is operative, and the distance between the inlet means of said one of said second and third conducting means and one of said appropriate outlets being greater than the distance between the other inlet means and said other of said appropriate outlets, whereby alternate rerouting of said fluid in said one of said second and third conducting means to said appropriate one of said outlets causes heat transfer to occur for differing periods of time between the respective said one fluid and the remaining fluids.