US20110094706A1

US20110094706A1 - Thermal stratified tank

Info

Publication number: US20110094706A1
Application number: US12/912,537
Authority: US
Inventors: Dritan Ramani
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-10-26
Filing date: 2010-10-26
Publication date: 2011-04-28
Also published as: EP2314970A1

Abstract

A thermal stratified tank has at east one first reservoir serving as a storage chamber for receiving a heat transfer medium, and at least one second reservoir, laterally adjoining the first reservoir via a partition (14), serving as an inflow and stratification chamber (15, 16). At least one through-opening (21) is provided in the partition between the first and second reservoirs. A guiding channel (27) leads into the second reservoir for supplying heat transfer medium. The guiding channel has an outlet which is constructed and/or arranged in such a way that during operation the inflow into the stratification chamber (15, 16) is substantially horizontal. A deflector wall (19), from which the inflowing heat transfer medium rebounds, is arranged at a spacing from the outlet and substantially in the inflow direction of the heat transfer medium.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Swiss Patent Application No. 01635/09 filed on Oct. 26, 2009 and Swiss Patent Application No. 01987/09 filed on Dec. 23, 2009, the entirety of each of which is incorporated by this reference.

FIELD OF THE INVENTION

The invention relates generally to a thermal stratified tank, and more specifically to a thermal stratified tank having at least one first reservoir serving as a storage chamber for receiving a heat transfer medium, at least one second reservoir, laterally adjoining the first reservoir via a partition, serving as an inflow and stratification chamber, and at least one through-opening, provided in the partition, between the first and second reservoirs.

PRIOR ART

Thermal stratified tanks serve as heat and cold accumulators and are used in housing technology as well as industry. They are essentially reservoirs that may be filled with a liquid medium, usually water. This is supplied via a flow pipe and removed via a return pipe. A thermal stratified tank can in principle cooperate with any desired heat source, from a conventional boiler through to a solar collector circuit that is rendered usable through heat exchange.
Excessively high flow speeds in the stratified tank lead to disturbances in stratification and therefore impair the efficiency of the thermal stratified tank. The hot water supplied in conjunction with solar collector systems is not of uniform temperature, but can be at very different temperatures depending on the time of day and weather. It is precisely in this case that stratification of the respective temperature ranges should be as free from turbulence as possible. For this purpose it is known to convey the heated water into a stratification chamber coaxially arranged inside the storage reservoir. From there the water flows in a stratified manner through rows of flow openings provided at different heights into the annular chamber of the storage reservoir that surrounds the stratification chamber. The stored water can finally be supplied to the consumer from this annular chamber. The drawbacks could only partly be tackled using stratified tanks constructed in this way, however. They are not convincing either in terms of construction or with regard to optimal stratification or, related thereto, with respect to efficiency either.
Other known thermal stratified tanks have similar drawbacks and become less efficient when a large number of different heat generators are connected. Some are specifically mentioned below.
In utility model DE 299 20 954 U1 there is a storage reservoir having three sub-regions located vertically one above the other. A different type of energy source or load is connected in each region according to the temperature requirements or conditions. A solar collector can disburden the heating of a building as a result of the given construction of the storage reservoir.
Utility model DE 202 20 554 U1 describes a water storage device with a plurality of rising pipes. Each rising pipe leads in this case into a different temperature layer, i.e. level, of the water storage device and is intended to make optimal stratification possible as a result. The stratification quality is associated with the number of rising pipes present and their length distribution.
From Offenlegungsschrift DE 197 43 563 A1 a thermal stratified tank is known with a vertically oriented storage reservoir. To prevent mixing losses the storage reservoir has a main storage volume and a secondary storage volume. An infeed ends in the secondary storage volume which is connected by an opening to the main storage volume. The opening, which connects secondary and main storage volumes, extends across the temperature gradients over the entire height of the thermal stratified tank. The secondary tank is formed in such a way that an inflowing liquid follows along walls of a predefined path and simultaneously stratifies into the corresponding temperature layer. To achieve effective stratification the path in the secondary tank is relatively long, however. The number of secondary tanks, for example, and therefore the infeeds, is limited due to the required long path length in the secondary tank. If the secondary storage volume forms an annular space around the main tank in particular, only one infeed may advantageously be laid as the secondary storage volume encompasses the main tank over more than half of its circumference. According to the disclosure two or more secondary tanks with corresponding infeeds are merely arranged vertically one above the other. However, this kind of vertically overlapping arrangement of secondary tanks has the drawback that the respective secondary storage volume does not simultaneously extend over the entire height of the thermal stratified tank. This severely limits the usefulness of each individual secondary storage volume. In particular the connected heat generator must be selected in accordance with the vertical position of the secondary tank. The use of a thermal stratified tank described in DE 197 43 563 A1 is therefore not completely versatile.
On the basis of the above knowledge it would be advantageous to create a thermal stratified tank in which the flow speed is slowed to the extent that stratification of a liquid medium is possible as a result of purely physical forces, and use of the heating energy is improved. A further advantage would be to provide a stratified tank to which a plurality of different heat generators may be connected. A further advantage would be is to provide a stratified tank which is inexpensive to produce. A further advantage would be to provide an efficient stratified tank in which the stratification is disrupted by neither the drawing-off of water nor the connection of heat generators.

SUMMARY OF THE INVENTION

According to the invention, a stratified tank comprises a guiding channel, inflow or infeed pipe, leads into the second reservoir for supplying a heat transfer medium (also called medium), in that the guiding channel (i.e. the inflow or the infeed pipe) and an associated outlet are constructed and/or arranged in such a way that during operation the heat transfer medium flows into the second reservoir substantially horizontally, and in that a deflector wall is arranged at a spacing from the outlet in the inflow direction of the heat transfer medium. A predominantly horizontal inflow is achieved for example by the guiding channel ending in a substantially horizontal pipe section. Deviations in the terminal pipe section from the horizontal in the order of magnitude of less than ±30 degrees, less than 20 degrees or less than 10 degrees are conceivable, however. The guiding channel, or the inflow or infeed pipe, optionally extends into the second reservoir. Any desired pipeline can serve as the inflow, infeed pipe or guiding channel. The deflector wall, which is arranged at a spacing from the outlet and in the inflow direction of the medium flowing into the stratification chamber, limits the further displacement of the inflowing medium in the inflow direction. The stratified tank according to the invention has the advantage that inflowing medium in the second reservoir has already been largely decelerated and the stratification of the medium in the stratified tank is therefore not disrupted by the medium flowing in. This has the advantage that a steep temperature gradient can be achieved in the stratified tank and the stratified tank is very efficient.
At least one connection opening may be provided on the second reservoir for supplying the heat transfer medium. At least one extraction port may be provided on the first reservoir for removing the heat transfer medium, in particular for example, a first extraction port at the bottom of the first reservoir and a second extraction port at the top of the first reservoir.
The deflector wall is advantageously arranged substantially normally with respect to the horizontal flow direction proportion of the inflowing medium. From this it follows that the deflector wall is usually also roughly vertically oriented. Deviations in the orientation of the deflector wall from the vertical in the order of magnitude of less than ±30 degrees, less than 20 degrees or less than 10 degrees are conceivable, however. As the inflow takes place from a horizontal pipe section, the horizontal flow proportion of the total inflow, which impinges onto the deflector wall substantially perpendicularly, is high. The inflowing medium appears at the deflector wall and is forced to reverse because of it. At the deflector wall the medium is deflected more or less strongly upwards or downwards according to its speed, temperature and density and is simultaneously diverted in the direction opposite to the initially horizontal inflow direction. The inflowing medium therefore rebounds at the deflector wall and in turn flows through the stratified chamber to the through-openings. The decelerated flow can accordingly be stratified further according to its temperature, i.e. its density, into the corresponding temperature layer en route to the through-openings. The design of the stratified chamber creates a long deceleration section for the inflowing medium and this is longer than the extent of the chamber in the horizontal direction. It is important that the inflowing medium is introduced into the stratification chamber in a laminar flow past the through-openings and in the direction of the deflector wall, and that the path up until the through-openings are reached is therefore enlarged.
The inflow direction is initially defined by the outlet and optionally a pipe section leading to the opening. The flow direction of the inflowing medium can undergo a slight change of direction, however, owing to the geometry of the chamber walls. If, for example, the inflow and stratification chamber is designed as an annular space that is curved in the horizontal plane, the chamber walls lead the flow onto the deflector wall in a curve. The deflector wall is arranged so as to be perpendicular to the roughly horizontal flow direction in this case as well.
The inflow and stratification chamber advantageously extends over at least 60%, at least 80% or substantially over the entire height of the second reservoir. The inflow and stratification chamber advantageously has an elongated design in its horizontal section, with the ratio of length to width being >2:1,>4:1 or >6:1. Instead of an inflow and stratification chamber a plurality of independent chambers may be present, each chamber extending over the entire height of the second reservoir. Inflow and stratification chambers may optionally extend over a section or various sections of the height of the second reservoir. If a plurality of inflow and stratification chambers is present these are advantageously separated from each other by deflector walls.
The at least one through-opening is advantageously provided in the partition laterally with respect to the flow direction, the partition separating the stratification chamber from the storage chamber.
A plurality of through-openings is advantageously provided which are arranged one above the other and vertically one above the other. The through-openings are distributed over a substantial part of the height of the partition, in particular over at least half the height of the partition or advantageously over three quarters of the height of the partition and most advantageously over the full height of the partition. One or more slit(s) may also be provided instead of individual through-openings. Basically the through-openings may also be arranged so as to be mutually axially offset.
The at least one through-opening is provided in a part of the partition which is located closer to the outlet of the guiding channel than the deflector wall. To produce a deceleration section which is as long as possible the guiding channel with the outlet is arranged a short distance from the wall of the stratification chamber opposing the deflector wall. Viewed in the horizontal direction the through-openings are provided in the partition in the first half of the spacing between outlet and deflector wall, in the first third, in the first quarter or in the first fifth of the spacing.
The solution provides that, viewed in the direction counter to inflow, the through-openings are arranged downstream of the outlet, i.e. in the shadow of the outlet of the guiding channel or in the shadow of the inflow direction. The through-openings are arranged behind a vertical plane which is defined by the outlet and is perpendicular to the inflow direction. The through-openings are advantageously at least 5 cm or at least 10 cm behind the outlet and/or at least 5 cm or at least 10 cm from said vertical plane in the counterflow direction. In this connection the inflow direction designates the initial flow direction as the medium exits the guiding channel or its outlet, and as it simultaneously flows into the stratified chamber. The initial flow direction on exiting from the outlet of the guiding channel is a horizontal flow, in particular substantially in the direction of the deflector wall or normally to the deflector wall. This has the advantage of it being possible to optimally use the stratified chamber space for stratification. Furthermore, the proportion of inflowing medium which flows directly via the through-opening(s) into the storage chamber without being deflected by the deflector wall beforehand is kept low.
The fact that no through-opening is arranged immediately before and/or to the side of the outlet ensures that the flow cannot pass directly into the storage chamber via a through-opening located at roughly the same height without previously having been stratified into the correct temperature level.
A wide variety of heat sources may be incorporated more efficiently using the thermal stratified tank according to the invention, and in particular also solar collector systems that work with heat pumps. The thermal stratified tank can have a round or polygonal outline. In a simple embodiment a stratification chamber is arranged on an outer wall of a central reservoir. This is generally significantly smaller than the central reservoir. The volume of the stratification chamber is chosen to be as small as possible but large enough to achieve stratification of the inflowing medium. The volume ratio of stratification chamber to storage chamber is advantageously 1:3 to 1:1, but may be at 1:2 to 1:1. In this case the sum of all stratification chamber volumes is meant where there is a plurality of stratification chambers.
The deflector wall is advantageously located at least 20 cm, at least 30 cm, or at least 40 cm from the outlet. This has the advantage that the inflowing medium must cover a relatively long distance before it can pass through the through-openings and into the stratified tank. The water speed on entering the stratification chamber of the thermal stratified tank may consequently be reduced to a flow speed of, for example, about 0.02 m/s or less. It is known that optimal stratification may be achieved with such flow speeds.
The two reservoirs expediently laterally border each other and in the process are at least partially demarcated from each other by a common wall, or a partition. The partition extends vertically along the extent of the reservoir. The partition substantially extends over the entire height of the first reservoir. The two reservoirs are substantially the same height. To achieve high storage efficiency it is advantageous to surround or encircle optimally all sides—in particular all lateral surfaces—of the first reservoir, i.e. of the storage chamber, with a second reservoir. The first reservoir therefore forms an inner chamber, also called a storage chamber, and the second reservoir forms an outer chamber, which at least partially, or completely, laterally encircles the inner chamber. The wall of the first reservoir may simultaneously be a partition here.
According to one embodiment, the first reservoir is a cylindrical reservoir having a first diameter, and the second reservoir is a cylindrical reservoir having a second, larger diameter. The first reservoir can consequently be received in the second reservoir, so an annular space is formed between the reservoirs. This is a particularly advantageous configuration which may be inexpensively achieved. The stratified tank is also insulated from the outside world by the annular space. The deflector wall or walls are provided on the outside of the first reservoir so it may be inserted in the second reservoir as a unit. The first reservoir is expediently coaxially arranged in the second reservoir. Other embodiments, which differ from this geometry, are also conceivable.
A plurality of deflector walls is advantageously provided which divide the annular space into a plurality of stratification chambers or recesses. Different heat generators, such as boilers or ovens, solar collectors inter alia, may be connected where a plurality of stratification chambers is present.
The guiding channel is advantageously designed as a rising pipe. A guiding channel of this kind may be inexpensively produced. However, it is also conceivable for the guiding channel to be part of the reservoir wall. The outlet of the guiding channel is advantageously constructed as an infeed curve. The provision of an infeed curve or another corresponding design of the end piece is intended to make the inflowing medium flow into the stratification chamber in a substantially non-turbulent manner. This means that the stratification of the medium in the stratification chamber should be disrupted as little as possible by the inflowing medium. A predominantly horizontal inflow, which is achieved, for example, by the infeed curve ending in a substantially horizontal pipe section, also contributes to a steady inflow.
Part of the guiding channel is expediently led outwards through the reservoir wall. A lateral connection opening is provided on the outer, i.e. outer-lying, part of the guiding channel and has a smaller cross-section than the guiding channel. This has the advantage that a reduction in the flow speed is already achieved at this point. The ratio of throughflow cross-section of the guiding channel to that of the connection or feeding pipe is advantageously greater than 1:1, greater than 1.5:1, greater than 2:1, or greater than 3:1. A cross-sectional ratio of at least 5:1 is particularly advantageous. This causes the inflowing medium to slow down by a factor of about 5. The ratio of the cross-sectional area of the guiding channel to the total cross-sectional area of the through-openings is advantageously greater than 3:1, greater than 5:1 or greater than 8:1. This configuration can bring about a further deceleration of the medium. The individual cross-sections of the feeding pipe, guiding channel and all of the through-openings are expediently selected such that a mean flow speed of less than about 0.03 m/s or less than about 0.02 m/s numerically results in the case of the through-openings. If, for example, the flow speed in the feeding pipe is 1 m/s, this may be reduced by a factor of 5 if the internal cross-section of the guiding channel is greater than that of the feeding pipe by a factor of at least 5. This means that when exiting the guiding channel the medium still has a speed of 0.2 m/s. If the cross-sectional area of all through-openings is accordingly selected so as to be ten times larger than the cross-section of the guiding channel or outlet, the mean flow speed in the case of the through-openings may be reduced by a factor of 10 to 0.02 m/s. To attain optimal stratification in the stratification chamber the cross-sectional ratios of the feeding pipe, guiding channel and through-openings will be selected such that, with a given flow speed in the feeding pipe, the resulting flow speed in the case of the through-openings is less than 0.03 m/s or less than 0.02 m/s.
A lateral inflow into the guiding channel also causes the inflowing medium to swirl and thereafter it flows through the guiding channel at a speed distribution that is uniform in cross-section, and optionally increases in and with the guiding channel. An expedient embodiment includes the guiding channel, in particular the connection opening of the guiding channel, being constructed with a connecting branch which ends in the guiding channel at an angle, at an angle between 60 and 120 degrees (i.e. at an angle of 90±30 degrees) or between 80 and 100 degrees (i.e. 90±10 degrees) or at approximately a right angle. A minimum length of the guiding channel, i.e. from the connection opening to the outlet, of 20 cm, 35 cm or of 50 cm, ensures that the exiting medium has a laminar flow.
The guiding channel is advantageously guided though the base of the second reservoir. This has the advantage that the foot projecting from the base can act as a stand base for the stratified tank. A first part of the guiding channel, which is guided outwards through the reservoir wall, can be made of a different material from that of a second part of the guiding channel, which projects into the second reservoir. The part of the guiding channel outside of the stratification chamber is expediently made of metal and the part located in the stratification chamber of plastics material.
A plurality of stratification chambers is advantageously provided and the guiding channels ending in the stratification chambers have different lengths. The length of the guiding channels may be selected in accordance with the anticipated temperatures of the inflowing medium. Adjusting the length of the guiding channels can provide for efficient stratification in the stratification chamber. A relatively long first guiding channel is provided for a primary heat generator, such as gas or oil heating, and this extends into the warmest zone of the stratified tank. A shorter, second guiding channel is provided for connecting solar collectors because the anticipated temperatures of the inflowing medium are, on average, lower. In addition to different lengths the guiding channels can have different diameters.
The first reservoir can expediently be constructed as an internal reservoir and be made substantially from plastics material. The second reservoir can accordingly be constructed as an external reservoir and be made from metal.
The first reservoir is divided into at least two partial chambers located one above the other which are thermally insulated from each other and the second reservoir is optionally also divided into at least two partial chambers located one above the other which are thermally insulated from each other. A panel, for example, may be arranged in horizontal orientation in the first reservoir and an additional panel may optionally also be arranged in the second reservoir for thermal insulation. The dividing panel in the first reservoir is solid, in other words does not have any continuous openings, in order to decelerate heat exchange of the upper warm layers with the lower cooler layers of the heat transfer medium in the storage chamber. The dividing panel in the second reservoir should comprise openings in order not to prevent stratification in accordance with the temperature of the inflowing medium but to decelerate heat exchange, i.e. heat transfer, of the upper warmer layers with the lower cooler layers during periods without the entry of heat medium from the heat generators. These measures help to maintain the stratification of the heat medium in the thermal stratified tank for as long as possible. The dividing panels contain heat-insulating material or are made from heat-insulating material.
According to one embodiment, a heat exchanger is fitted in at least the first reservoir. This may be used as a fresh water station and may be fitted in the top half of the tank. The heat exchanger advantageously has first and second heat exchanger sections, with the first heat exchanger section being arranged in the second reservoir and the second heat exchanger being arranged in the first reservoir. This arrangement has the advantage that in the first heat exchanger section the flowing fresh water may already be heated to the temperature prevailing in the stratification chamber. The fresh water then passes into the second heat exchanger section where it is heated to the temperature prevailing in the upper layers of the first internal reservoir. The heat exchanger is advantageously produced from spirally or helically wound heat exchanger tubes. An embodiment of this kind has the advantage that a large heat exchange surface may be provided on the smallest space. The heat exchanger tubes are upwardly helically wound, so the fresh water passes from layers at a lower temperature into layers at a higher temperature as if flows through the heat exchanger. Other types of known heat exchanger are also conceivable.
According to a further embodiment, a heat exchanger or an additional heat exchanger is provided in the second reservoir, i.e. in the stratification chamber. A heat exchanger of this kind is suitable for connecting thermal solar collectors. This has the advantageously that a separate heat exchanger, as is usually required in known tank systems, may be omitted.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention will be described in more detail hereinafter with reference to the drawings:

FIG. 1 shows a three-dimensional schematic view of a first exemplary embodiment of a thermal stratified tank consisting of an external reservoir and an internal reservoir arranged coaxially therein, between which a plurality of annular chambers is formed which are used as stratification chambers,

FIG. 2 shows a section through the stratified tank of FIG. 1,

FIG. 3 shows the details of a foot,

FIG. 4 schematically shows a view of a second exemplary embodiment of a stratified tank with a heat exchanger in a stratification chamber,

FIG. 5 shows a section through the stratified tank of FIG. 4,

FIG. 6 schematically shows a view of a third exemplary embodiment of a stratified tank with a heat exchanger which controls both stratification chambers, in particular a view of a stratified tank with a fresh water station,

FIG. 7 shows a section through the stratified tank of FIG. 6,

FIG. 8 shows various examples of stratified tanks that are round in cross-section and have annular spaces,

FIG. 9 shows further examples of stratified tanks with polygonal outline or with a plurality of stratification chambers arranged one above the other,

FIG. 10 shows in a perspective view a plurality of exemplary embodiments of internal reservoirs with deflector walls arranged thereon and through-openings arranged in different ways,

FIG. 11 schematically shows various forms of through-openings in plan view,

FIG. 12 a shows a schematic view of a fourth exemplary embodiment of a thermal stratified tank consisting of an external reservoir and an internal reservoir arranged coaxially therein, between which a plurality of annular chambers is formed which act as stratification chambers, external reservoir and internal reservoir having sectional insulation, and

FIG. 12 b shows a section through the stratified tank of FIG. 12.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

As may be seen from the stratified tank diagram of FIG. 1, the thermal stratified tank according to the invention comprises an external reservoir 11 in which an internal reservoir 13 is arranged. The internal reservoir 13 is formed by a cylindrical partition 14 which is inserted into the external reservoir 11. At least one free space remains between the internal reservoir 13 and the external reservoir 11 and in the present case this has the form of an annular space. If, as in the present exemplary embodiment, the cylindrical partition 14 is arranged coaxially to and a spacing from the external reservoir 11 a central inner space which serves as a storage space 17 is produced and an external annular space 15 is produced which serves as a stratification chamber 16. The annular space 15 can be divided by deflector walls 19 into one or more chamber(s) 16 or annular spaces. Each chamber 16 is fitted with at least one inflow or guiding channel, in particular a rising pipe 27 with infeed curve 29, via which the flow can flow from a heat generator, not shown in the figures. If a plurality of inflow or guiding channels is present in a chamber 16 the outlets thereof are advantageously arranged at different heights or temperature levels. As a result a plurality of heat generators may optionally be connected via various inflow or guiding channels to the same chamber 16, according to their flow temperature. Cooler flows are introduced into lower-lying regions than warmer flows in the process. Rising pipe 27 and infeed curve 29 are advantageously constructed in such a way that a predominantly laminar flow leaves the infeed curve in a substantially horizontal direction. This is achieved for example by the infeed curve ending in a horizontal pipe section.
The partition 14 separating the annular space 15 from the inner space 17 is provided with a plurality of through-openings 21 which are arranged one above the other in a vertical direction. The through-openings 21 consequently allow medium to be exchanged between annular space 15 and inner space 17 at different height levels.
The annular space 15 (or the chambers 16 constructed therein) has the function of receiving the inflowing medium and of stratifying it during its dwell time. The flows and/or return flows from one or more heat exchanger(s) flow into the annular space and are stratified on the basis of their specific density, which is temperature-dependent. The stratified medium then flows through at least some of the through-openings 21 (according to its respective density and temperature) into the inner space 17, which has the function of a storage space, in which there is scarcely still any flow. Cold water may be removed from the inner or storage space 17 via a runoff 31 and be fed back into the heat exchanger(s).
If a plurality of stratification chambers 16 is present there is usually a separate guiding channel 27 for each one. An exception from this rule occurs if a heat exchanger is fitted in the stratification chamber 16 (see description relating to FIGS. 4 and 5 below). Furthermore, a large number of through-openings 21 are associated with each stratification chamber 16 and these are arranged one above the other in the axial direction. The advantage of an arrangement with a plurality of stratification chambers 16 with individual guiding channels 27, which, for example, are formed by rising pipes 27 with infeed curves 29, lies in the fact that, compared with single-chamber systems, different flows, which originate from different heat generators (i.e. the flows) and are introduced into the stratification chambers 16 via different guiding channels 27, cannot intermix. This results in more selective stratification and therefore an energy saving.
According to the specific embodiment of FIG. 1, three partitions or deflector walls 19 are arranged in the annular space for substantially perpendicular division or break down of the annular space into three stratification chambers 16.
In the additional embodiments according to FIG. 8, the annular space is divided using at least one partition or deflector wall 19. According to the illustrated exemplary embodiments one or up to six deflector wall(s) is/are used to divide the annular space into one or more stratification chamber(s) 16. The annular space can therefore be divided over its circumference, i.e. viewed from above as a horizontal section, into a plurality of, for example two to four, stratification chambers 16. A section example with three stratification chambers 16 can be seen in FIG. 2. Further section examples with stratification chamber numbers that differ therefrom can be seen in FIG. 8. According to alternative examples in FIG. 9 neither the external reservoir nor the internal reservoir 11, 13 have to have a circular cross-section in section. Instead any desired shapes are conceivable, from triangular to polygonal. Even irregular cross-sections are possible in particular in the case of specific fitting situations. The annular space 15 can consequently have any desired geometry that differs from a purely circular ring. Reference is also made to the fact that more than one internal reservoir 13 is also possible, see for example the second exemplary embodiment in FIG. 9 with internal reservoirs 13 a and 13 b. In this embodiment with coaxially arranged internal reservoirs 13 a, 13 b two annular spaces are placed inside each other in the manner of onion layers and both annular spaces are divided into a large number of stratification chambers.
A common feature of the different embodiments of the annular spaces 15, i.e. the inflow or stratification chambers 16, is clear in the horizontal sectional drawing (FIGS. 8 and 9 (reference numerals of parts with the same function are indicated here by way of example for only some of the exemplary embodiments)): a chamber 16 contains at least two conveying sides 40, 42 and one deflector side 41. The deflector side 41 adjoins each conveying side and is constructed as a vertical deflector wall 19. The conveying sides are used to convey the inflowing medium in the direction of the deflector wall. In a horizontal view the two conveying sides 40, 42, together with the, shorter, deflector side 41 located therebetween, form a substantially U-shaped deflection zone. The deflection zone advantageously extends over the entire height of the chamber 16. At their contact points or lines the conveying sides 40, 42 each form an angle of about 90 degrees with the deflector side 41. According to an alternative embodiment the angles can deviate herefrom, however. The angles should advantageously lie in a range from approximately 60 to 120 degrees or from 80 to 100 degrees. The conveying sides 40, 42 may be curved. If the first conveying side 40 is curved the deflector side 41 adjoins its concave surface, in particular at an angle of 90 degrees. One of the conveying sides, in particular the inner conveying side 42, is simultaneously also part of the partition 14. An inflow or stratification chamber 16 is advantageously elongate in its horizontal extension and optionally curved.
The function of the annular space 15, or the stratification chamber or chambers 16, is described using the exemplary embodiment according to FIG. 2. The annular space 15 is divided here into three separate stratification chambers 16 by three radially applied deflector walls 19 that extend vertically and are advantageously arranged perpendicularly to the reservoir walls. The stratification chambers 16 are elongated and have a curve.
The stratification chambers 16 are connected to the storage reservoir 17 of the thermal stratified tank by at least one through-opening 21 respectively. The through-openings 21 are each arranged in the vicinity of the wall 19, which is located on the side remote from the outlet of the infeed curve 29. The outlet 22 defines an exit plane normally to the exit flow. In relation to the flow direction—shown by means of arrows—the through-openings 21 are each located downstream of the outlets 22 of the infeed curve 29 ending in said stratification chambers 16, or downstream of the plane defined by the outlet 22 or, in other words, in the shadow of the outlet. The outlets 22 of the infeed curve 29 are, moreover, arranged much closer in the case of one deflector wall than the other 19 and are oriented in such a way that the inflowing liquid medium firstly flows to the more remote deflector wall 19, is forced back at that location and deflected or rebounds and as it flows back passes the exit plane in order to be conveyed via the through-openings 21 into the storage chamber 17. The dimension of the rising pipe 27 and the spacing of the outlet 22 from the deflector wall 19 is adjusted according to the anticipated flow volumes in such a way that the flow can be decelerated in the stratification chamber 16 to the extent that the medium is stratified. The flow of the medium conveyed through the annular space 15 or its individual stratification chambers 16 is decelerated by the given arrangement and is stratified, optionally by dropping or rising, according to its specific density in relation to its surroundings before it can pass into the central storage reservoir 17. It is noted here that, alternatively, a plurality of inflow channels could also be present in each case.
FIG. 10 shows deflector wall embodiments with different arrangements of the through-openings 21. The deflector walls 19 are radially provided on the cylindrical partition 14, as already demonstrated in the exemplary embodiment according to FIG. 2. The through-openings 21 of the partition 14 are positioned between two deflector walls 19 respectively, but as described above advantageously closer to the deflector wall 19 in whose vicinity the conveying channel is also located. The through-openings 21 can be distributed over the entire axial length, or over the entire height of the cylinder. This can be advantageous if the temperature of the inflowing flow is subject to extreme variations and/or stratification should be possible in all density zones. If the temperature of the flow is known and/or the storage space 17 should receive a certain, controlled density stratification a certain storage zone can be selected that is coordinated therewith in which the passage of the stratified medium should be allowed. Through-openings 21 are only provided in these selected zones. As each stratification chamber 16 may be filled with medium at different temperatures it may be advantageous to individually determine the position of the through-openings 21 in each stratification chamber 16.
Different forms and sizes of the through-opening 21 are possible. As demonstrated in FIG. 11 elongate or compact through-opening forms may be used equally as well as circular ones. It is also conceivable to provide slits instead of discrete through-openings.
Even before the liquid medium passes from the conveying channel into the stratified tank the flow speed of the inflowing medium is advantageously decelerated. This is brought about in the foot 23 of the rising pipe 27. As can be seen in FIG. 3 the foot 23 of the rising pipe 27 consists of a pipe end that is closed at one side and which can be applied to the conveying channel 27 by way of a guide piece 24. At the side, the foot 23 has a connection 25 ending at an angle. The connection 25 ends in the foot 23 in such a way that the medium flowing in through the connection 25 impacts on the inside of the pipe end. The result of this is that the inflowing medium is swirled. A significant reduction in the inflow speed may already be achieved in combination with a pipe cross-section of the rising pipe 27 that is larger relative to the connection cross-section. Swirling of the medium as it flows into the rising pipe 27 ensures that, viewed over the pipe cross-section, the inflowing medium has a uniform speed distribution. Instead of the described supply of medium a deflector element could also be provided which swirls the inflowing medium.
As also emerges from FIG. 1 the distal end piece of the conveying channel 27 is constructed as a curve 29. The point of this is for the medium flowing into the stratification chamber to have a substantially laminar flow. This has the advantage that the inflowing medium cannot cause excessive swirling in the stratification chamber 16. An appropriately selected spacing of the deflector wall 19 from the outlet of the conveying channel 27 can decelerate the inflowing medium in the stratification chamber. Impact and rebound of the flow on the deflector wall leads to a banked-up flow so the speed of the inflowing medium is reduced to the extent that the medium starts to stratify according to temperature and density. The spacing of the deflector wall from the outlet is selected such that the speed of the medium following impact on the deflector wall is reduced to <0.03 m/s or to <0.02 m/s. It is therefore expedient to reduce the speed of the inflowing medium in at least two stages, namely once on entry into the conveying channel 27 by selecting a favorable cross-section ratio of feeding pipe and guiding channel and then in the stratification chamber 16 by selecting a sufficiently long flow path of the inflowing medium from the outlet to the through-openings 21.
FIGS. 12 a and 12 b show a further stratified tank with the same reference numerals designating parts with the same function as illustrated above. In contrast to the stratified tank shown in FIGS. 1 and 2 the infeed curve 29 leads from outside directly into the stratification chamber 16. A rising pipe 27 is optional. The connecting branch 25 can be attached directly to the infeed curve 29. Each infeed curve advantageously leads into the stratified tank at the temperature level which as far as possible matches the temperature (or the density) of the heat transfer medium supplied by the heat generator. Furthermore, there is sectional insulation consisting of a first sectional insulating panel 32 in the storage chamber 17 and a second sectional insulating panel 30 in the stratification chamber 16 in FIG. 12 a. The sectional insulating panels 30 and 32 are horizontally oriented. The first sectional insulating panel 32 is designed as a solid panel. The second sectional insulating panel 30 is fitted with at least one compensation opening 28. The at least one compensation opening 28 allows the medium that has flowed in to rise and/or sink for stratification. The two panels 30, 32 divide stratification chamber and storage chamber into two regions respectively, in particular into two partial chambers respectively. The respective two regions, upper and lower regions, of the stratification chamber and storage chamber are separated on a horizontal plane so as to be heat insulating. The panels 30, 32 delay heat dissipation from the warmer upper regions into the colder lower regions of the storage chamber. This embodiment primarily demonstrates advantageous storage properties during operation with relatively long interruptions in heat generation, such as an interruption in the power generation of solar cells in the night.
It may be seen from FIGS. 4 and 5 that a stratification chamber 16 may be used to receive a heat exchanger 33 which, for example, may be coupled to thermal solar collectors. The heat which is given off by these heat exchangers 33 into this stratification chamber 16 or which is removed therefrom causes stratification of the medium regions affected by way of purely physical forces.
The described construction of the thermal stratified tank means that stratification takes place substantially within the stratification chambers 16. The medium stratified according to its temperature only passes via the through-opening(s) 21 corresponding to the respective temperature layer and into the corresponding storage layer in a final step following successful stratification.
Furthermore, as may be seen from FIGS. 6 and 7, a fresh water station 35 may be located in the upper region of the stratified tank. The fresh water station 35 is used to produce hot fresh water from cold fresh water. The fresh water station consists of a heat exchanger which consists of a first heat exchanger section 37 and a second heat exchanger section 39 adjoining the fist heat exchanger section 37. The first heat exchanger section 37 extends through the stratification chamber(s) 16. The second heat exchanger section 39 is arranged in the upper region of the storage space 17 where the temperature of the medium is highest. The heat exchanger 35 is advantageously produced from a pipe, such as a copper pipe, of a specific diameter which is spirally wound. The first heat exchanger section 37 has a first diameter which roughly matches the mean diameter of the annular chamber 15 and the second heat exchanger section 39 has a second diameter which is smaller than the diameter of the internal reservoir 13. It is conceivable for the second heat exchanger section 39 to have two or more heat exchanger sections that are helically placed inside each other. A large heat exchanger surface may be produced as a result, so heating may take place in a relatively narrow section of the stratified tank.
During operation the cold fresh water firstly passes through the first heat exchanger section which is fitted in the stratification chamber(s) 16. The water then passes into the second heat exchanger section which is fitted in the top hot water region of the storage reservoir 17. There the water is raised to the temperature which prevails in the top region of the stratified tank.
Compared with others this variant of a fresh water station 35 has the advantage that it can manage completely without controllers, valves, pumps and measuring instruments (sensors, flowmeters, etc.). This in turn has the advantage that this fresh water station 35 is fail-safe and inexpensive to maintain. A fresh water station 35 of this kind reaches its full range of functions only when combined with the described stratified tank. As the cold fresh water is firstly guided through the stratification chambers 16 it cools the warm medium that is located there. However, unlike in other reservoirs this does not affect the temperature stratification of the stratified medium in the storage chamber 17. Instead the cold medium sinks to the bottom in the stratification chamber 16 already and re-enters the layer with the same properties (i.e. layer with the same temperature or density).
The stratified tank construction according to the invention has significant advantages: the fresh water cascade arranged in the stratified tank does not require any external fittings (pumps, valves etc.) as the water is conveyed by the prevailing water pressure of the fresh water feed. No flow occurs which is caused by pumps. This means the stratification chamber(s) 16 can operate extremely efficiently.
A thermal stratified tank has at least one first reservoir serving as a storage chamber for receiving a heat transfer medium, and at least one second reservoir, laterally adjoining the first reservoir via a partition 13, serving as an inflow and stratification chamber 16. A first extraction port 31 is provided at the bottom of the first reservoir and a second extraction port (not shown) at the top for the removal of heat transfer medium respectively. A connection opening 25 for supplying the heat transfer medium is provided on the second reservoir. At least one through-opening 21 is also provided in the partition between the first and second reservoirs. A guiding channel 27 is connected to at least one connection 25 and this leads into the second reservoir and advantageously extends into the second reservoir. The guiding channel has an outlet 22 which is arranged such that during operation the inflow into the stratification chamber is substantially horizontal. A deflector wall 19 is arranged at a spacing form the outlet and substantially in the flow direction. The inflowing medium rebounds from this wall. The through-opening 21 is provided in part of the partition 13 which, viewed counter to the inflow direction, is located downstream of the outlet of the guiding channel. The described arrangement has the advantage that the inflowing medium has to cover a relatively long distance until it reaches the through-openings. The speed of the inflowing medium is reduced by the deflector wall 19 to the extent that the medium is stratified. The speed of the inflowing medium is advantageously already reduced once on entering the guiding channel. This takes place by way of appropriate selection of the cross-sectional ratio of the feeding pipe and the guiding channel.

Claims

1. A thermal stratified tank, comprising:

at least one first reservoir serving as a storage chamber for receiving a heat transfer medium;

at least one second reservoir, laterally adjoining the first reservoir via a partition, serving as an inflow and stratification chamber;

at least one through-opening; provided in the partition; between the first and second reservoirs;

a guiding channel leading into the second reservoir for supplying a heat transfer medium, the guiding channel and an associated outlet constructed in such a way that during operation the heat transfer medium flows into the second reservoir substantially horizontally; and

at least one deflector wall arranged at a spacing from the outlet in an inflow direction of the heat transfer medium.

2. The thermal stratified tank according to claim 1, wherein the at least one through-opening is located closer to the associated outlet of the guiding channel than the deflector wall and, viewed in the direction counter to the inflow, is downstream of the associated outlet.

3. The thermal stratified tank according to claim 1 wherein the spacing between the associated outlet and the deflector wall is such that a speed of inflowing heat transfer medium before reaching the at least one through-openings attains less than one of 0.03 m/s or 0.02 m/s.

4. The thermal stratified tank according to claim 1, wherein the first reservoir is a first cylindrical reservoir with a first diameter and the second reservoir is a second cylindrical reservoir with a second, larger diameter, the first reservoir arranged in the second reservoir, to form an annular space between the first and second reservoirs.

5. The thermal stratified tank according to claim 4, wherein the at least one deflector wall comprises a plurality of deflector walls that divide the annular space into at least one of a plurality of stratification chambers and a plurality of stratification recesses.

6. The thermal stratified tank according to claim 1 or 5, wherein the at least one deflector wall is provided on an outside of the first reservoir, and can be inserted in the second reservoir as a unit.

7. The thermal stratified tank according to claim 1 wherein a ratio of a cross-sectional area of the guiding channel to a cross-sectional area of the a feeding pipe is greater than at least one of 1.5:1, 2:1 and 3:1.

8. The thermal stratified tank according to claim 1 wherein a ratio of a cross-sectional area of the guiding channel to a total cross-sectional area of the through-openings is greater than at least one of 3:1, 5:1 and 8:1.

9. The thermal stratified tank according to claim 1 wherein the guiding channel is constructed as a rising pipe and having a length of at least 20 cm and the outlet of the guiding channel constructed as an infeed curve.

10. The thermal stratified tank according to claim 1 wherein a part of the guiding channel extends outwards through a wall of the second reservoir and further comprising a lateral connecting opening on the part of the guiding channel which has a smaller cross-section than the guiding channel.

11. The thermal stratified tank according to claim 1, further comprising a connecting branch which ends in the guiding channel at a substantially 90 degree angle with a maximum deviation of approximately ±30 degrees.

12. The thermal stratified tank according to claim 1, further comprising a plurality of stratification chambers, a plurality of guiding channels, the plurality of guiding channels ending in the plurality of stratification chambers and having at least one of different lengths and different diameters.

13. The thermal stratified tank according to claim 1, further comprising a plurality of through-openings arranged vertically one above the other.

14. The thermal stratified tank according to claim 1, further comprising at least one heat exchanger fitted in at least one of the first and second reservoir.

15. The thermal stratified tank according to claim 14, wherein the at least one heat exchanger has a first and a second heat exchanger section, the first heat exchanger section in the first reservoir and the second heat exchanger section in the second reservoir.

16. The thermal stratified tank according to claim 1, wherein

the storage chamber is divided into at least two regions located one above the other that are heat insulated from one another and

the inflow and stratification chamber is divided into at least two regions located one above the other that are heat insulated from one another.