Hot water storage device

Abstract

Hot water storage tank (1), comprising at least a container (2) with a volume (4) enclosed by a container wall (3) for storing hot water (5) and a supply line (6) for cold water (7), wherein the supply line (6) extends from outside the container (2) over the container wall (3) into the volume (4) up to an outlet (8) of the supply line (6), characterized in that the supply line (6) has a smaller first flow cross-sectional area Q1 (9) upstream of the outlet (8) and a larger second flow cross-sectional area Q2 (10) between the first flow cross-sectional area Q1 (9) and the outlet (8).

Description

[0001] The invention relates to a hot water storage tank.

[0002] Hot water systems can include a hot water storage tank to store the heated water. Particularly when using renewable energy sources like solar thermal energy, favorable conditions for heat generation and hot water demand can occur at different times. To ensure that the required quantity and temperature of solar thermally heated water can be delivered simultaneously, hot water storage tanks are used to store the heated water until needed. Cold water is fed into the hot water storage tank and heated there, for example, via a heat exchanger. For energy-efficient use of the hot water stored in the tank, the mixing of the incoming cold water with the already heated water should be minimized.The volume of the hot water storage tank extends from a lower to an upper section. In the upper section, the hot water settles as usual, while the lower section contains the cold water due to its higher density.

[0003] It is known that cold water is supplied via a downpipe. The downpipe extends from the outside into the volume of the hot water storage tank and then runs towards a lower section of the tank. The cold water is thus transferred directly into the area of ​​the hot water storage tank where the cold water stored there settles over time. The pipe section used is usually cylindrical, meaning that the cross-sectional area of ​​the pipe is essentially constant. Due to the high flow velocity of the incoming cold water, the cold water mixes with the hot water in a relatively large portion of the hot water storage tank.

[0004] It is also known to perforate the wall of the downpipe to reduce the flow velocity of the cold water. While the perforated pipe does minimize the flow velocity through its holes, this requires a defined pipe length along which the holes are distributed. The cold water flows into the heated hot water along the length of the perforated section, mixing it as it passes through the height of the perforated pipe, resulting in increased mixing of the hot water.

[0005] The solutions mentioned each lead to a certain mixing of the water, on the one hand due to the high flow velocity present, and on the other hand due to the outflow through the perforation holes along the length of the downpipe.

[0006] Based on this, the object of the invention is to propose a hot water storage tank that at least partially overcomes the problems of the prior art described above. In particular, the hot water storage tank is intended to achieve less mixing of the water stored in it.

[0007] These problems are solved by the features of independent claim 1. Further advantageous embodiments of the solution proposed here are specified in the independent claims. It should be noted that the features listed in the dependent claims can be combined with one another in any technologically meaningful way and define further embodiments of the invention. Furthermore, the features specified in the claims are further specified and explained in the description, which also presents further preferred embodiments of the invention.

[0008] This is achieved using a hot water storage tank, comprising at least a container with a volume enclosed by a container wall for storing hot water, and a cold water supply line. The supply line extends from outside the container, across the container wall, into the volume, and up to an outlet. Upstream of the outlet (e.g., in the region of the container wall or downstream of it), the supply line has a smaller first flow cross-sectional area Q1, and between the first flow cross-sectional area Q1 and the outlet, a larger second flow cross-sectional area Q2.

[0009] A hot water storage tank is specifically designed for supplying hot water to a building, for example. It can be configured as a buffer tank and / or a stratified storage tank. It may include a heat exchanger for transferring heat, for example, to a heating circuit of a heating system. The heat exchanger can be, for instance, a coiled pipe, which (when installed) is typically located in a lower (geodesically) section of the hot water storage tank.

[0010] The hot water storage tank can be designed to hold heated or to-be-heated drinking or domestic hot water, or to hold a heat transfer fluid from the heating circuit. The volume of the hot water storage tank or container can be completely filled with water or additionally, at least partially, with air (as an internal expansion volume).

[0011] To replenish used hot water, hot water storage tanks typically have a cold water inlet (supply line), i.e., a supply of fresh water, often connected to a domestic water system or a water main. The cold water inlet, or rather its outlet, is usually located in the lower part of the hot water storage tank to promote temperature stratification within the water volume. The supply line extends from outside the tank, along the tank wall, into the volume, and up to an outlet. The cold water flows through the supply line towards the outlet. Accordingly, in the direction of cold water flow, the first flow cross-sectional area Q1 is located upstream of the second flow cross-sectional area and upstream of the outlet.

[0012] It is proposed here that the supply line be designed, at least partially, as a diffuser, in which, due to an increase in the flow cross-sectional area, the flow velocity of the cold water supplied to the volume is reduced to such an extent that mixing of the supplied cold water with the heated hot water within the volume is minimized. This allows for a higher degree of temperature stratification and thus a larger usable volume of hot water.

[0013] In particular, the cold water can only flow out of the supply line via the one outlet; therefore, perforation of the supply line is specifically not intended.

[0014] In particular, the ratio Q2 / Q1 is at least two, preferably at least three, and most preferably at least four. In particular, the ratio Q2 / Q1 is at most 20, preferably at most 10.

[0015] In particular, a third flow cross-sectional area changes continuously in a section of the supply line that is located between the first flow cross-sectional area and the second flow cross-sectional area.

[0016] In particular, the third flow cross-sectional area increases continuously in this section. Specifically, the supply line is designed such that the flow cross-sectional area increases exclusively in this section.

[0017] In particular, the section extends exclusively in a straight line, i.e., without any bends or curves. Specifically, the supply line extends from the outside through the tank wall to the inside and then continues in a straight line downwards to the (geodesically) lower region of the volume. Specifically, in the section where the flow cross-sectional area changes (continuously), the supply line runs exclusively parallel to the direction of gravity (when the hot water storage tank is installed as intended).

[0018] In particular, the feed line widens conically in this section, meaning the section is designed in the shape of a cone. Specifically, the opening angle of each wall of the cone is between 5 and 12 degrees, preferably between 7 and 10 degrees, relative to a parallel arrangement of the walls.

[0019] In particular, a laminar / steady flow of the supplied cold water should be maintained. This laminar / steady flow is maintained by the section acting as a diffuser, thus reducing the flow velocity at the outlet or at the second cross-sectional area of ​​the flow path according to mass conservation (continuity equation for steady flows of impermeable fluids). The length of the widening section can be determined via the opening angle and the desired flow velocity at the outlet or at the second cross-sectional area of ​​the flow path.

[0020] In particular, the first flow cross-sectional area is the smallest flow cross-sectional area of ​​the supply line (at least of the part of the supply line located within the volume). In particular, the second flow cross-sectional area is the largest flow cross-sectional area of ​​the supply line (at least of the part of the supply line located within the volume). In particular, the outlet has the largest flow cross-sectional area.

[0021] In particular, the volume extends from a lower area to an upper area of ​​the container, with the outlet in the lower area and an inlet of a hot water extraction line located above the outlet in the upper area.

[0022] In particular, a heat exchanger line is arranged at least in the lower area and within the volume, wherein the heat exchanger line extends spirally around the supply line at least in the lower area.

[0023] It should be noted as a precaution that the numerical terms used here ("first", "second", etc.) primarily serve (only) to distinguish between several similar objects, quantities, or processes, and thus do not necessarily dictate any dependency and / or sequence between these objects, quantities, or processes. Should a dependency and / or sequence be required, this is explicitly stated here, or it will be obvious to a person skilled in the art upon studying the specific configuration described. Where a component can occur multiple times ("at least one"), the description of one of these components may apply equally to all or some of the multiple components, but this is not mandatory.

[0024] This proposal features a hot water storage tank with a specially designed cold water inlet pipe. At least one section of this inlet pipe is designed like a diffuser (e.g., a funnel-shaped pipe), so that the flow velocity of the cold water is reduced within the inlet pipe itself, minimizing mixing with the already heated hot water. This allows for superior stratification within the hot water storage tank, resulting in a larger usable volume of hot water.

[0025] The invention and its technical context are explained in more detail below with reference to the accompanying figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the situations described in the figures and combine them with other components and findings from the present description. It should be emphasized that the figures, and especially the depicted dimensions, are only schematic. They show: Figure 1: a hot water storage tank in a perspective view; Figure 2: the hot water storage tank after Fig. 1 in a side view in section; Figure 3: the hot water storage tank after Fig. 1 and 2 in another side view; Figure 4: the lower area of ​​the hot water storage tank Figs. 1 to 3in a side view in section; Fig. 5: the hot water storage tank after Figs. 1 to 4 in a first state, in a side view in section; Fig. 6: a known hot water storage tank in a first state, in a side view in section; Fig. 7: the hot water storage tank after Fig. 5 in a second state, in a side view in section; and Fig. 8: the hot water storage tank after Fig. 6 in a second state, in a side view in section.

[0026] Figure 1 shows a hot water storage tank 1 in a perspective view. Fig. 2 shows the hot water storage tank 1 after Fig. 1 in a side view in section. Fig. 3 shows the hot water storage tank 1 after Fig. 1 and 2 in another side view. Fig. 4 shows the lower section 13 of the hot water storage tank 1 after Figs. 1 to 3 in a side view in section. Figs. 1 to 4 will be described together below.

[0027] The hot water storage tank 1 has a container 2 with a volume 4 enclosed by a container wall 3 for storing hot water 5, and a supply line 6 for cold water 7. The supply line 6 extends from outside the container 2, across the container wall 3, into the volume 4, and up to an outlet 8 of the supply line 6. Upstream of the outlet 8, and also in the region of the container wall 3 (and downstream of it), the supply line 6 has a smaller first flow cross-sectional area Q1 9, and between the first flow cross-sectional area Q1 9 and the outlet 8, a larger second flow cross-sectional area Q2 10.

[0028] The volume 4 of the container 2 extends from a lower region 13 to an upper region 14 of the container 2, wherein the outlet 8 is located in the lower region 13 and an inlet 15 of a withdrawal line 16 for the withdrawal of hot water 5 from the container 2 is located above the outlet 8 in the upper region 14.

[0029] The hot water storage tank 1 has a heat exchanger in the form of a heat exchanger line 17 for heat exchange with a heating circuit of a heating system (not shown). The heat exchanger is designed as a coiled pipe (heat exchanger line 17) which (in the assembled state) is located in a (geodesically) lower section 13 of the hot water storage tank 1. The heat exchanger line 17 extends spirally around the supply line 6, at least in the lower section 13.

[0030] The supply line 6 extends from outside the container 2, across the container wall 3, into the volume 4, and up to an outlet 8 of the supply line 6, with the flow direction of the cold water 7 running through the supply line 6 towards the outlet 8. Accordingly, in the flow direction of the cold water 7, the first flow cross-sectional area Q1 9 is arranged upstream of the second flow cross-sectional area Q2 10 and upstream of the outlet 8.

[0031] The supply line 6 is at least partially designed in the manner of a diffuser, in which, due to an (increasing) enlargement of the third flow cross-sectional area 11, the flow velocity of the cold water 7 supplied to the volume 4 is reduced to such an extent that the mixing of the supplied cold water 7 with the heated hot water 5 within the volume 4 is as minimal as possible (see Figs. 4 to 8This allows for a higher quality of temperature stratification and thus a larger usable volume of hot water.

[0032] A third flow cross-sectional area 11 of the supply line changes continuously in a section 12 of the supply line 6, which is arranged between the first flow cross-sectional area 9 and the second flow cross-sectional area 10.

[0033] The third flow cross-sectional area 11 in section 12 increases continuously and is conical in shape. The supply line 6 is designed such that in section 12, only the third flow cross-sectional area 11 increases up to the second flow cross-sectional area 10. The opening angle 18 of each wall of the cone is between 5 and 12 degrees relative to a parallel arrangement of the walls.

[0034] Section 12 extends in a straight line, i.e., it is neither bent nor curved. The supply line 6 extends from the outside through the tank wall 3 into the interior of the tank 2 and then extends downwards in a straight line with section 12 to the (geodesically) lower region 13 of the volume 4. Within section 12, where the flow cross-sectional area 11 changes continuously, the supply line 6 runs exclusively parallel to the direction of gravity (when the hot water storage tank 1 is installed as intended).

[0035] The first flow cross-sectional area 9 is therefore the smallest flow cross-sectional area 11 of the supply line 6. The second flow cross-sectional area 10 is the largest flow cross-sectional area 11 of the supply line 6. The outlet 8 has the largest flow cross-sectional area 10, 11.

[0036] Fig. 5shows the hot water storage tank 1 after Figs. 1 to 4 in an initial state, in a side view in section. Fig. 6 shows a known hot water storage tank 1 in its first state, in a side view in section. Fig. 7 shows the hot water storage tank 1 after Fig. 5 in a second state, in a side view in section. Fig. 8 shows the hot water storage tank 1 after Fig. 6 in a second state, in a side view in section. The Figs. 5 to 8 will be described together below. The explanations regarding the Figs. 1 to 4 will be referred.

[0037] Fig. 5 and 7 show the hot water storage tank 1 with the expanding supply line 6. Fig. 6 and 8 show a known hot water storage tank with a known supply line 6. In the first state ( Figs. 5 and 6The mixing of water 5, 7 in container 2 is shown when the level of cold water 7 is low. In the second state ( Figs. 7 and 8 ) shows the mixing of the water 5, 7 in the container 2 when the level of the cold water 7 is high.

[0038] The supply line 6 of the hot water storage tank 1 to Fig. 5 and 7 Section 12 is designed like a diffuser (e.g., as a funnel-shaped pipe) so that the flow velocity of the cold water 7 is reduced in the supply line 6, i.e., in section 12, to such an extent that mixing with the already heated hot water 5 is minimal. This allows for a high degree of stratification within the hot water storage tank 1, thus providing a larger usable volume of hot water 5. Reference symbol list

[0039] 1 Hot water storage tank 2 Tank 3 Tank wall 4 Volume 5 Hot water 6 Supply line 7 Cold water 8 Outlet 9 First flow cross-sectional area Q1 10 Second flow cross-sectional area Q2 11 Third flow cross-sectional area 12 Section 13 Lower area 14 Upper area 15 Inlet 16 Draw-off line 17 Heat exchanger line 18 Opening angle

Claims

1. Hot water storage tank (1), comprising at least one container (2) with a volume (4) enclosed by a container wall (3) for storing hot water (5) and a supply line (6) for cold water (7), wherein the supply line (6) extends from outside the container (2) over the container wall (3) into the volume (4) up to an outlet (8) of the supply line (6), characterized in that the supply line (6) has a smaller first flow cross-sectional area Q1 (9) upstream of the outlet (8) and a larger second flow cross-sectional area Q2 (10) between the first flow cross-sectional area Q1 (9) and the outlet (8).

2. Hot water tank (1) according to claim 1, characterized in that a ratio Q2 / Q1 is at least two.

3. Hot water tank (1) according to one of the preceding claims, characterized in thata third flow cross-sectional area (11) in a section (12) of the supply line (6) which is arranged between the first flow cross-sectional area (9) and the second flow cross-sectional area (10) changes continuously.

4. Hot water tank (1) according to claim 3, characterized in that the third flow cross-sectional area (11) in the section (12) increases continuously and exclusively.

5. Hot water tank (1) according to one of the preceding claims 3 and 4, characterized in that the section (12) extends exclusively in a straight line.

6. Hot water tank (1) according to one of the preceding claims 4 and 5, characterized in that the supply line (6) widens conically in the section (12).

7. Hot water tank (1) according to one of the preceding claims, characterized in that the outlet (8) has the largest flow cross-sectional area (11).

8. Hot water tank (1) according to one of the preceding claims, characterized in that the volume (4) extends from a lower region (13) to an upper region (14) of the container (2), wherein the outlet (8) is arranged in the lower region (13) and an inlet (15) of a withdrawal line (16) for the hot water (5) arranged in the volume (4) is arranged above the outlet (8) in the upper region (14).

9. Hot water tank (1) according to claim 6, characterized in that a heat exchanger line (17) is arranged at least in the lower region (13) and within the volume (4), which extends spirally around the supply line (6) at least in the lower region (13).

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