Domestic water communal conduit network with parallel cooling network and drinking water conduits

Abstract

The invention relates to a municipal drinking water distribution network with a plurality of drinking water pipes for supplying end consumers with drinking water, wherein there is at least one ice storage system at at least one of the end consumers to supply heating and / or cooling energy to the end consumer, wherein the ice storage system has pipes that define a cooling network, wherein the pipes of the cooling network are laid in heat exchange with the drinking water pipes. The invention also relates to a method for cooling a municipal drinking water network, wherein a cooling network of a private or municipal ice storage system is used to influence the temperature of the drinking water in the municipal drinking water network.

Description

[0001] The invention relates to a municipal drinking water supply network, comprising a plurality of drinking water pipes for supplying end users with drinking water, wherein there is at least one ice storage system at at least one of the end users to supply heating and / or cooling energy to the end user, wherein the ice storage system has pipes that define a cooling network.

[0002] Due to global warming, that is, in particular the associated increased solar radiation and increased air temperature, and the increasing development and / or paving of surfaces, an increasing heat input into the ground results from an increasingly heated surface, consequently leading to a warming of the drinking water in drinking water pipes laid in the ground.

[0003] Although the heat input into the ground via the surface is dampened with increasing depth, current studies, for example from projects funded by the German Technical and Scientific Association for Gas and Water (DVGW), show that temperature peaks attributable to the heat input, with corresponding dampening and delay, can be detected down to a depth of 1.5 m.

[0004] These temperature peaks manifest as locally elevated soil temperatures of up to 25°C at a depth of 1.5 m. These elevated soil temperatures cause the drinking water conveyed through underground pipes, which are typically laid at a depth of between 0.5 m and 1 m, to warm up. Studies funded by the DVGW (German Technical and Scientific Association for Gas and Water) also show that the water temperature in the drinking water pipe network can rise locally to as high as 30°C during the summer months.

[0005] For several years, water suppliers have been pointing out that the drinking water temperature in the pipe network is locally and consistently above 25 °C, resulting in a discrepancy between regulations and practical reality. According to standards such as DIN EN 806-2 or DIN 1988-200, the temperature of cold water must not exceed 25 °C within a maximum of 30 seconds after the tap is opened. Below this maximum drinking water temperature of 25 °C, increased Legionella contamination can be effectively avoided (see DVGW Worksheet W 551-2 2022-08). Furthermore, elevated temperatures promote the formation of biofilms, within which opportunistic premise plumbing pathogens (OPPP) can also proliferate.

[0006] The elevated water temperatures in the drinking water network already pose a significant challenge for water suppliers with regard to drinking water hygiene and thus legal aspects, as well as communication with customers due to complaints about hot water or discussions with the district heating sector. Against this backdrop, interest in and pressure to identify effective countermeasures are increasing.

[0007] Established countermeasures include cold water flushing of public supply networks / private household pipes, also to achieve a drinking water temperature within the compliant range, or drinking water recirculation in private households. However, these methods are complex and insufficient or only implementable with difficulty, and in the case of cold water flushing, they are also characterized by high water consumption. A future possible solution to the problem of drinking water heating is the laying of drinking water pipes at depths of up to 2 meters, but this represents a costly solution.

[0008] From the state of the art, cold district heating and cooling networks (also known as 5th generation district heating and cooling networks) are also known. These networks represent a technical variant of a heat supply network that operates with low transmission temperatures close to ambient temperature, i.e., in a temperature range of 5 °C to 35 °C, preferably between 10 °C and 25 °C. The cold district heating network can provide both heat and cooling, and simultaneously. The temperature level is so low that it is insufficient to directly supply the connected buildings with heat.

[0009] In cold district heating networks, decentralized water-to-water heat pumps must therefore be installed to raise the temperature level to the required level for the building's heating system. Unlike conventional district heating networks, hot water generation and building heating are not achieved directly via heat exchangers, but rather via heat pumps that extract their thermal energy from the district heating network. Cooling can be achieved either directly via the cold district heating network or, if necessary, indirectly via the heat pumps. These heat pumps are installed in cold district heating networks and raise the temperature level of the heat from the network to the flow temperature in the building's heating circuit.

[0010] Cold district heating networks enable the development of environmental heat sources, i.e., renewable heat sources. These renewable heat sources include, among others, waste heat, wastewater heat, well water, groundwater, and solar thermal energy. Ice storage systems or ground-source heat storage systems also serve as heat sources.

[0011] German patent application DE 10 2019 111 184 A1 discloses such a cold heating network for temperature control of at least one building. The cold heating network has a first closed circuit for supplying heat to or removing heat from a heat pump assigned to the respective building, and a second circuit which indirectly exchanges thermal energy from a heat source located away from the building, preferably a ground source heat pump, with the first closed circuit, wherein a latent heat storage system is arranged between the first closed circuit and the second circuit.

[0012] In connection with latent heat storage systems, the prior art also discloses document DE 10 2019 121 166 B4. This document discloses a modified heat exchanger tube for ice storage applications as a cold storage system. Specifically, it discloses a plastic tube for a latent heat storage system, comprising a hollow tube body for conducting a heat-conducting fluid. The tube body is designed to be at least partially wetted with a heat storage fluid, and a multitude of crystallization nuclei formed during ice formation from a mineral are permanently or inseparably attached to the outer surface of the tube body.

[0013] The present invention aims to achieve an improvement over the prior art. Known disadvantages are to be eliminated or at least reduced.

[0014] In a municipal drinking water supply network as presented above, this is achieved according to the invention by laying the pipes of the cooling network in heat exchange with the drinking water pipes.

[0015] In other words, the invention relates to a municipal drinking water supply network in which renewable energy sources are used to limit the reduction of the drinking water temperature in the drinking water pipes to a more compliant temperature range, so that a permissible maximum temperature for the drinking water is not exceeded.

[0016] Advantageous embodiments are claimed in the dependent claims and are explained in more detail below.

[0017] It has proven advantageous if the pipes of the cooling network are laid at least partially parallel to the drinking water pipes.

[0018] This arrangement advantageously allows for the cooling of the drinking water pipes via the cooling network through heat exchange, thanks to short connection paths. The advantageously short connection paths also reduce the influence of the ambient temperature. These advantages result in the availability and storage of preferably pre-conditioned, i.e., pre-cooled, drinking water in the drinking water pipes.

[0019] Furthermore, it is advantageous if a reservoir is integrated into the drinking water supply network, which is also specifically integrated into the cooling network as a heat source.

[0020] The elevated reservoir is preferably designed as a drinking water reservoir and configured in such a way that heat extraction is technically feasible in winter. Due to the preferably available possibility of heat extraction, the extracted heat can preferably be used as a heat source for the at least one heat pump of the cooling network and for heating processes.

[0021] Furthermore, it is advantageous to integrate additional heat exchangers into the drinking water supply network and / or cooling network in order to use regeneratively generated energy as active cooling of the cooling network.

[0022] The embodiment of the municipal drinking water supply network according to the invention, with an additional heat exchanger, preferably for integration into the cooling network, enables the additional use of renewable energies. Furthermore, the integration of an additional heat exchanger into the drinking water supply network for connection to a cooling network is conceivable in a manner that is advantageous with regard to heat extraction.

[0023] It has proven advantageous if the ice storage system is designed to utilize crystallization energy.

[0024] By designing the ice storage system, i.e., the latent heat storage system, to utilize crystallization energy, faster and more efficient charging of the ice storage can be achieved through a suitably reduced subcooling. This is particularly advantageous when operating the ice storage as a pure cold storage system, and thus especially in summer. This is because a cooling medium with a sufficiently low thermal energy can be provided via heat exchange with the cold storage system, thereby ensuring reliable domestic hot water cooling.

[0025] Furthermore, it is advantageous if the drinking water pipes are laid at a depth of approximately 0.8 m to approximately 1.2 m (or at a depth of 2.0 m + / - 25%).

[0026] By installing drinking water pipes at a depth of 0.8 m to 1.2 m, existing drinking water pipes can be used advantageously with regard to cost savings through the use of existing pipe infrastructure.

[0027] In a further embodiment of the municipal drinking water supply network according to the invention, positioning the drinking water pipes at a depth of 2.0 m + / - 25% is also advantageously conceivable. This second embodiment allows the base temperature of the drinking water to be advantageously reduced under otherwise constant conditions. The cooling capacity required to achieve a water temperature within the compliant temperature range can thus be advantageously reduced.

[0028] Furthermore, it is advantageous if the drinking water pipes and the pipes of the cooling network are laid in such a way as to maintain a temperature of approximately 10 °C in both pipe systems all year round.

[0029] Maintaining a consistent drinking water temperature throughout the year ensures reliable protection against bacterial growth in the summer, thus promoting water hygiene. In winter, a minimum temperature of 10°C protects the water pipes from freezing, advantageously ensuring a reliable water supply. Operating the cooling network at 10°C also facilitates the efficient extraction of heat energy by the heat pump. Cooling the drinking water pipes is preferably achieved indirectly using the heat pumps.

[0030] A method for cooling a municipal drinking water network is also presented, whereby a cooling network of a private or municipal ice storage system is used to influence the temperature in the drinking water of the municipal drinking water network.

[0031] The method for cooling the municipal drinking water network preferably uses a private or municipal ice storage system, which advantageously makes it possible to cool the drinking water network using renewable energy sources in the interest of environmental protection.

[0032] In connection with the presented method, it is advantageous if the medium in the pipes of the cooling network is in heat exchange with the drinking water in the drinking water pipes.

[0033] The heat-exchanging connection between the medium in the pipes and the drinking water in the drinking water pipes allows for a direct extraction of cold from the drinking water, i.e., a heat transfer to the medium, which can be achieved advantageously with regard to the shortness of the interactions.

Claims

1. Municipal drinking water supply network, comprising a multitude of drinking water pipes for supplying end users with drinking water, wherein there is at least one ice storage system at at least one of the end users to supply heating and / or cooling energy to the end user, wherein the ice storage system has pipes that define a cooling network, characterized by the fact that The pipes of the cooling network are laid in heat exchange with the drinking water pipes.

2. Municipal drinking water supply network according to claim 1, characterized by the fact that The pipes of the cooling network are laid at least partially parallel to the drinking water pipes.

3. Municipal drinking water supply network according to one of claims 1 or 2, characterized by the fact that A reservoir is integrated into the drinking water supply network, which is also specifically integrated into the cooling network as a heat source.

4. Municipal drinking water supply network according to one of claims 1 to 3, characterized by the fact thatAdditional heat exchangers are integrated into the drinking water supply network and / or cooling network to use regeneratively generated energy as active cooling of the cooling network.

5. Municipal drinking water supply network according to one of claims 1 to 4, characterized by the fact that The ice storage system is designed to utilize crystallization energy.

6. Municipal drinking water supply network according to one of claims 1 to 5, characterized by the fact that The drinking water pipes are laid at a depth of approximately 0.8 m to approximately 1.2 m.

7. Municipal drinking water supply network according to one of claims 1 to 6, characterized by the fact that The drinking water pipes and the pipes of the cooling network are laid in such a way as to maintain a constant temperature of approximately 10 °C in both pipe systems throughout the year.

8. Method for cooling a municipal drinking water network, wherein a cooling network of a private or municipal ice storage system is used to influence the temperature in the drinking water of the municipal drinking water network.

9. Method for cooling a municipal drinking water network according to claim 8, wherein the medium in the pipes of the cooling network is in heat exchange with the drinking water of the drinking water pipes.

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