METHOD FOR FILLING AN INTERNAL EXPANSION AREA OF A HOT WATER STORAGE TANK, COMPUTER PROGRAM, CONTROL AND REGULATION DEVICE, HOT WATER STORAGE TANK AND USE OF COMPRESSED AIR

Description

[0001] The invention relates to a method for filling an internal expansion area of ​​a hot water storage tank, a hot water storage tank and a computer program.

[0002] Hot water or drinking water supply systems typically include a hot water storage tank to store the heated water. To compensate for temperature fluctuations and the associated volume changes of the stored hot water, these systems usually incorporate an expansion vessel. This can be, for example, an external diaphragm expansion vessel, which has a diaphragm separating a water-holding compartment from a gas-holding compartment, often nitrogen. The diaphragm is therefore securely sealed within the expansion vessel to ensure a particularly gas-tight seal. Such external expansion vessels, as described, for example, in DE 10 2017125 672 A1, are generally considered wear parts and are therefore replaced when their functionality is impaired (particularly due to leakage or diaphragm failure).

[0003] Furthermore, internal expansion sections are known in which an air cushion located in the upper part of the hot water storage tank is separated from the stored water by a baffle plate floating on the water surface in the hot water storage tank (compare, for example, DE 6 93 13 798 U1) or an elastic bladder (compare, for example, DE 201 09 610 U1). In the case of a baffle plate moving up and down in the hot water storage tank, there is no gas tightness, so that gas from the air cushion can dissolve in the water and / or gas from the water can escape into the air cushion. Due to the lack of gas tightness of the baffle plate, the air cushion changes, and in particular is consumed, through gas exchange with the stored water and must be regularly adjusted, especially replenished.

[0004] According to the current state of the art, this involves closing the fresh water supply to the hot water storage tank and opening a hot water draw-off point located geodetically below the storage tank to create a negative pressure that can build up an air cushion. A problem with this method is the need for a hot water draw-off point located geodetically below the storage tank, for example, in the case of hot water storage tanks located in a basement. Furthermore, this relatively complex procedure must be carried out regularly.

[0005] German patent DE 10 2017 125 672 A1 discloses an expansion vessel, among other things, for a heating system, which enables significantly reduced-effort monitoring of the functionality of an expansion vessel integrated into a piping system. In this expansion vessel, two chambers are separated by a clamped flexible diaphragm, and a non-contact distance measuring instrument is directed at a central area of ​​the diaphragm. This allows for the detection of insufficient pressure in the second chamber and, if necessary, the addition of pressurized gas. A disadvantage of this design is its unsuitability for a hot water storage tank, as the flexible diaphragm has a limited service life and is unsuitable for accommodating large volumes. Furthermore, the non-contact distance measuring instrument is complex, and the necessary window can become opaque due to dirt or condensation, thus preventing measurement.

[0006] WO 2020 / 122 483 A1 also deals with an expansion vessel containing an elastic membrane or bladder for holding water. The bladder is arranged around or coaxially to a central axis of the expansion vessel. The expansion vessel includes a compressor connected to an air chamber, sensors for detecting the water level and pressure in the air chamber, and valves for releasing air from the air chamber and / or adding and / or releasing water. The expansion vessel may have a control system that activates the compressor or opens valves based on the parameters detected by the sensors. This solution, too, is unsuitable for use as a hot water storage tank and the associated storage of large volumes of water due to the elastic bladder.

[0007] EP 0 117 389 A2 discloses an expansion vessel for holding a fluid that changes its volume. In a closed vessel, an air cushion is present above the fluid, while in an open vessel, the atmosphere is present. Between the fluid and the air cushion, a (liquid) separating agent, an oil degreaser, and a sensor that detects the level of the separating agent are provided. If the fill level of the expansion vessel falls below a certain limit, the sensor can trigger a shut-off valve to close an outlet of the expansion vessel, thus preventing the release of the separating agent. The use of a liquid separating agent is unsuitable for a hot water storage tank because the separating agent could enter the domestic hot water. Furthermore, the proposed expansion vessel does not offer a means of replenishing the air cushion.

[0008] NL 1 016 219 C1 describes a closed system for heating water. This system can include an extension of a water tank that absorbs water when heated and releases it when cooled. The system is particularly suitable for very large expansion tanks and thermal storage tanks with a volume of up to 2,000 m³. Degassing of the contained liquid must be prevented. A separating element is useful for this purpose; however, a membrane appears difficult to install due to its large diameter. The introduction of a nitrogen cushion is proposed. Consequently, the system is unsuitable for systems providing domestic hot water in buildings.

[0009] WO 2010 / 097 566 A1 discloses a liquid container in which a piston element separates a first container section from a second container section. The piston element has an external shape designed to create a sealing connection between the container and the piston element when fluid pressure occurs. The piston element may have an opening with a valve to allow fluid flow from the first container section to the second. This liquid container does not provide a direct means of filling the second container section and therefore cannot contribute to the present problem.

[0010] Based on this, the object of the invention is to propose a method for filling an internal air cushion of a hot water storage tank, a computer program, and a hot water storage tank that at least partially overcome the problems of the prior art described above. In particular, the method for filling an internal air cushion of a hot water storage tank should be simple and location-independent, as well as enabling automated execution. This should, in particular, reliably compensate for the dissolution of air in the hot water during operation of the hot water storage tank.

[0011] Furthermore, the invention should not significantly increase the complexity of a hot water storage tank and should require only minor structural changes.

[0012] These problems are solved by the features of the independent claims. 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.

[0013] This is achieved by a method for filling or refilling an internal expansion area of ​​a hot water storage tank, wherein a movable separating element designed as a float is arranged in the hot water storage tank, which separates the expansion area and the water, and the method comprises at least the following steps: Detecting the position or change in position of the movable separating element in the hot water storage tank by means of a proximity sensor or a proximity switch, initiating a filling of the expansion area upon reaching a predetermined first limit value or a predetermined first limit position, whereby a pressurized gaseous fluid is supplied via an opening of the hot water storage tank.

[0014] In particular, a gaseous fluid pressurized to (above-atmospheric) pressure is introduced through the opening of the hot water storage tank. This pressurized gaseous fluid can then be directed, in particular, to the (internal) expansion zone of the hot water storage tank.

[0015] A hot water storage tank is a familiar storage device for hot water supply, for example, to a building. It can be designed as a buffer tank and / or a stratified storage tank. It may include a heat exchanger to absorb a heat flow, for example, for heat exchange with a heating circuit of a heating system. Hot water storage tanks typically have a cylindrical reservoir for water, which may be surrounded by thermal insulation.

[0016] The hot water storage tank can have, as part of its receiving area, at least one internal expansion chamber that can be filled with a gaseous fluid. In other words, this can mean that the hot water storage tank forms an internal cavity, part of which is designed as an expansion chamber. The expansion chamber, which is not a separate unit, is essentially (only) bounded by the wall of the hot water storage tank and a movable partition. The preferably single expansion chamber is located adjacent to the reservoir for the water to be stored. The gaseous fluid can be, in particular, ambient air. Other gases, such as nitrogen, can also be used for this purpose.

[0017] The expansion zone compensates for volume fluctuations in the water stored in the hot water tank, caused by temperature-related variations in water density. For example, heating of the water by the heat exchanger can lead to an increase in the water's volume. To replenish the hot water drawn, hot water tanks typically have a fresh water supply, often connected to a domestic water system or mains water supply. The hot water tank is therefore pressurized with water. To ensure a sufficient volume for the expansion zone within the hot water tank to accommodate these volume fluctuations, the expansion zone must contain a minimum volume of gaseous fluid.Overfilling the expansion zone of the hot water storage tank could also lead to a loss of function, characterized by the escape of gaseous fluid from a hot water tap during use. Furthermore, a high hot water storage tank capacity is desirable, but this is reduced by the expansion zone. Therefore, the volume of the expansion zone should be between a minimum and a target volume to ensure proper functionality of the hot water storage tank even when its capacity is fully utilized.

[0018] To separate the intake area from the expansion area, at least one (movable and / or deformable) separating element must be provided. The separating element cannot usually guarantee a gas-tight separation between the expansion area and the water, so that gas contained in the expansion area can dissolve in the water, thus reducing the amount of gas contained in the expansion area.

[0019] In particular, the separating element can be a flat, three-dimensional structure. Alternatively, the separating element can have a cylindrical shape with a low height, where the base area can largely correspond to the cross-sectional area of ​​the receiving area, thus ensuring a largely complete separation of the water surface and the expansion area, and can have a lower density than water, and therefore be suspended on the contained water.

[0020] The separating element is designed as a float and can rest on the surface of the hot water. The separating element can be designed, in particular, to follow the position or shape of the water surface. The separating element can be multi-part, i.e., with several floats. In particular, at least one guide element can be provided in the hot water storage tank to guide the separating element when the (geodetic) position and / or shape of the water surface in the hot water storage tank changes. The guide element can be designed as a central rod located in a guide opening in the separating element. The guide element can be located on the wall of the hot water storage tank and guide the separating element around its circumference during movement.Preferably, the separating element (vertically) is movable in the hot water storage tank (guided), in particular due to a change in the gas volume in the expansion area (occurring during operation) and / or a change in the water volume in the reservoir.

[0021] The hot water storage tank may have an opening in a wall of the hot water storage tank for refilling the gaseous fluid, which may be located in a geodetically upper area of ​​the hot water storage tank in the installation position to prevent the escape of contained water.

[0022] The at least one opening (which can be opened and closed) can be located within the expansion zone and penetrate the wall of the hot water storage tank. A pressure- and liquid-tight fluid line can be associated with it.

[0023] According to an advantageous embodiment, the opening can include a valve. The valve can, in particular, be arranged in the wall in such a way that the supply of gaseous fluid to the expansion area is possible, but the escape of gaseous fluid through the valve is prevented.

[0024] According to an advantageous embodiment, the valve can be a Schrader, Presta, or Dunlop valve. Advantageously, these valve types can be connected to, or already be connected to, known air pumps for inflating motor vehicle or bicycle tires.

[0025] The system is designed to detect the position and / or changes in position of the movable baffle within the hot water storage tank. This is achieved primarily through sensors or automatically. Specifically, the position is measured as the geodetic elevation of the baffle, and changes in position are measured as the magnitude and / or rate of any change in geodetic elevation. Therefore, the movement of the baffle within the hot water storage tank must be monitored. It is also possible to detect the position and / or changes in position of the movable baffle within the hot water storage tank by analyzing other operating parameters of the hot water storage tank (temperature, pressure, water flow, etc.) and incorporating them into a calculation for the acquisition and / or adaptation of the measured value.

[0026] If the detection process indicates that the separating element has reached a predetermined first limit value or a predetermined first limit position, an (automatic) refilling of the expansion zone is initiated or started (automatically and / or immediately). The limit value can, for example, relate to a change in position. The first limit position can be a predetermined upper geodetic height of the separating element in the hot water storage tank.

[0027] Additionally, the system can detect when a predetermined second limit value or position of the separating element is reached (after or during the filling process), and then continue filling the expansion zone until this second limit value or position is reached. This second limit value could, for example, refer to a change in position. The second limit position could be a predetermined lower geodetic elevation of the separating element within the hot water storage tank. If the second limit value is reached, the filling process can be stopped (automatically).

[0028] According to an advantageous embodiment, a simple implementation of the method proposed here can be achieved by connecting an air pump, for example for bicycle or motor vehicle tires, to the opening and by controlled operation of the air pump producing a (always) sufficiently large volume of the expansion area.

[0029] According to an advantageous embodiment, the position of the separating element relative to the hot water storage tank can be detected. When the separating element reaches a (predefined) first limit position within the detection range, this could indicate a (predefined) minimum volume of the expansion zone. Reaching the first limit position can thus be recognized or defined as the point in time to initiate the filling of the expansion zone.

[0030] According to a further advantageous embodiment, when the need to refill the expansion zone is detected, i.e., when the first limit position is reached, a pump can be automatically started to fill the expansion zone with the gaseous fluid. In a simple embodiment of the proposed method, the pump can be operated for a defined filling period. This filling period is defined as a pre-determined duration during which the pump fills the expansion zone from its minimum volume to the target volume.

[0031] According to an advantageous embodiment, the system can additionally detect when the separating element reaches a second limit position within the expansion range, which may correspond to a (predefined) target volume. The pump could then be automatically started when the minimum volume is detected and switched off again when the target volume is detected.

[0032] According to an advantageous embodiment, the fluid can also be stored in a pressurized gas container, for example, a carbon dioxide or nitrogen container. The pressurized gas container can, for example, be arranged in a replaceable manner and regularly exchanged as needed. The pressurized gas container can also be filled with compressed air and, if necessary, refilled using an (external) compressor.

[0033] The position or change in position of the movable separating element in the hot water storage tank can be detected, particularly through its closed wall. This means, in particular, that contactless detection is possible. Specifically, no sight glasses are required for (optical) observation of the separating element's movement within the wall. Proximity sensors or switches selected from the following groups can be used for this purpose: magnetic proximity sensors / switches, inductive proximity sensors / switches, capacitive proximity sensors / switches, and ultrasonic proximity sensors / switches.

[0034] According to an advantageous embodiment, at least one proximity sensor or proximity switch, particularly a magnetic switch (such as a reed switch, reed relay, and / or Hall sensor), can be used to detect the position of the separating element relative to the hot water storage tank, especially the first and / or second limit position. This sensor can be arranged in the area of ​​the hot water storage tank wall. The separating element can have a sensorily detectable component (for example, a magnet) in a corresponding (external) area near the proximity switch. It is understood that the proximity switch can also be located on the separating element, and a detectable component can also be located in or on the wall.

[0035] This makes it advantageous to implement a fully automated execution of a proposed procedure.

[0036] Furthermore, a computer program is proposed which is designed to (at least partially) carry out a method presented here. In other words, this specifically concerns a computer program (product) comprising instructions which, when executed by the device, cause it to perform a method proposed here.

[0037] Another aspect that is proposed is a machine-readable storage medium on which the computer program is stored. This machine-readable storage medium is typically a computer-readable data carrier.

[0038] In particular, a control unit, for example, of a heating appliance connected to the hot water storage tank, is proposed, configured to carry out a method proposed herein. The control unit may, for example, include and / or have a processor. In this context, the processor may, for example, execute the method stored in a memory (of the control unit). Advantageously, operating data and reference values ​​(for example, an ignition flow rate and / or a target power) for carrying out a method presented herein may also be stored in the memory of the control unit. The control unit may, in particular, include an electrical connection to a device for detecting when the lower and / or upper limit position of the separating element in the receiving area of ​​the hot water storage tank has been reached, and to a pump.An electrical connection here refers to a wired or wireless connection for the transmission of data.

[0039] Another aspect proposed is a hot water storage tank featuring a separating element designed as a float, which separates an internal expansion zone filled with gaseous fluid from the stored water. Furthermore, an opening in a wall of the hot water storage tank within the expansion zone, encompassing a valve, is provided. Additionally, the hot water storage tank incorporates a sensor, designed as a proximity sensor or proximity switch, to detect the position of the separating element through the closed wall of the tank.

[0040] According to an advantageous embodiment, the hot water storage tank can include a device for detecting the position of the separating element relative to the hot water storage tank.

[0041] In particular, the use of compressed air to fill an internal expansion chamber is proposed. The compressed air can be supplied, in particular, by means of a pump or a pressure accumulator.

[0042] The details, features, and advantageous designs discussed in connection with the process can also occur in the computer program, control unit, and / or hot water storage tank presented here, and vice versa. Therefore, the explanations provided therein can be fully applied to further characterize the features of the other aspects.

[0043] 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.

[0044] This document describes a method for filling the internal expansion zone of a hot water storage tank, a hot water storage tank itself, and a computer program that at least partially solve the problems described with reference to the state of the art. In particular, the method and the hot water storage tank contribute to creating a simple and location-independent way to fill the internal expansion zone of a hot water storage tank.

[0045] Furthermore, the invention allows for fully automated refilling of the internal expansion area, which can significantly increase user comfort and also eliminate costs for possible maintenance appointments to refill the expansion area.

[0046] 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: Fig. 1: a hot water storage tank proposed here.

[0047] Fig. 1Figure 1 shows an exemplary and schematic representation of a proposed hot water storage tank 1. This tank can have a receiving area 2 enclosed by a wall 3. The receiving area 2 can include an expansion area 9 in the upper region of the receiving area 2 (in the installation position), which can contain a pressurized gas, in particular air.

[0048] The receiving area 2 can be separated from the expansion area 9 by a separating element 11. The separating element 11 can, in particular, have a density lower than that of water and thus float on the water it contains.

[0049] The hot water storage tank 1 can have an opening 4 with a valve 5 in the wall 3 within the expansion zone 9, which can be connected to a pump 6. The pump 6 can pressurize a gaseous fluid, in this example air, and supply it to the expansion zone 9 via the opening 4.

[0050] The hot water storage tank 1 can also be connected to a heating device 8, for example, to a heating circuit that can heat the hot water contained in the hot water storage tank 1 via a heat exchanger (not shown here). Hot water can be drawn from the hot water storage tank 1 via a draw-off pipe 10, which opens in an upper section to accommodate temperature stratification within the hot water storage tank 1 and thus ensure that hot water at the highest possible temperature is drawn off. Overfilling the expansion zone 9 can cause the (air-filled) expansion zone 9 to expand up to the opening of the draw-off pipe 10, causing air (from the expansion zone 9) to escape from the draw-off pipe 10.

[0051] Proximity switches 15 can also be arranged in the wall 3 of the hot water storage tank 1 in the area of ​​a first limit position 12 and a second limit position 13. The separating element 11 can also have a position indicator 14 in an outer area near the wall 3. The first limit position 12 can indicate a minimum volume and the second limit position a target volume of the expansion area 9. For example, the proximity switches 15 can be designed as magnetic switches and the position indicator 14 as a magnet.

[0052] A control unit 7 can be configured to carry out the procedure proposed here and can be electrically connected to the proximity switches 15 and the pump 6 for this purpose. This enables fully automated execution of the proposed procedure. For example, when the control unit 7 detects that the separating element 11 has reached the first limit position 12 via a proximity switch 15, the pump 6 can be activated by means of a control signal. This allows the expansion zone 9 to be filled with compressed air, enabling the separating element 11 to move towards the second limit position 13. Upon reaching the second limit position 13, the control unit 7 can switch off the pump 6. Reference symbol list

[0053] 1 Hot water storage tank 2 Intake area 3 Wall 4 Opening 5 Valve 6 Pump 7 Control and monitoring unit 8 Heating unit 9 Expansion area 10 Extraction pipe 11 Separating element 12 First limit position 13 Second limit position 14 Position indicator 15 Proximity switch

Claims

1. Method for filling an internal expansion area (9) of a hot water storage tank (1), wherein a movable separating element (11) designed as a float is arranged in the hot water storage tank (1), which separates the expansion area (9) and the water, and the method comprises at least the following steps: - detecting a position or position change of the movable separating element (11) in the hot water tank by means of a proximity sensor or a proximity switch (15), - initiating filling of the expansion chamber (9) when a predetermined first limit value or a predetermined limit position (12) is reached, wherein a pressurised gaseous fluid is supplied via an opening (4) in the hot water tank (1).

2. Method according to one of the preceding claims, wherein the gaseous fluid is supplied through a valve (5) arranged in the opening (4).

3. Method according to one of the preceding claims, wherein the position of the movable separating element (11) in the hot water storage tank (1) is detected by its closed wall (3).

4. Method according to one of the preceding claims, wherein the reaching of a predetermined second limit value or a predetermined second limit position (13) of the separating element (11) is additionally detected and the filling of the expansion area (9) is carried out until the second limit value or the second limit position (13) is reached.

5. Method according to one of the preceding claims, wherein the gaseous fluid is pressurised by a motor-driven and controllable pump (6) and / or a pressure accumulator.

6. Method according to claim 5, wherein a filling process is carried out by starting up the motor-driven pump (6) and / or opening a connection to the pressure accumulator for a defined period of time.

7. Hot water storage tank (1), comprising - a separating element (11) which is movably arranged in the hot water storage tank (1) and designed as a float, which separates an internal expansion area (9) filled with gaseous fluid from stored water, - an opening (4) in a wall (3) of the hot water storage tank (1) in the area of the expansion area (9), comprising a valve (5); and - a sensor system for detecting the position of the separating element (11) through the closed wall (3) of the hot water storage tank (1), designed as a proximity sensor or proximity switch (15).

8. Hot water storage tank (1) according to claim 7, comprising a device for detecting the position of the separating element (11) relative to the hot water storage tank (1).

9. Hot water storage tank (1) according to one of claims 7 to 8, wherein the hot water storage tank (1) is connected to a control and regulating device (7) which is electrically connected to a device for detecting the position of the separating element, wherein the control and regulating device (7) is designed to carry out the steps of a method according to one of claims 1 to 4.

10. Computer program comprising instructions that cause a hot water storage tank (1) according to claim 9 to execute a method according to one of claims 1 to 4.