EP3601688B1 - Method for operating a circulation system, and circulation system - Google Patents

Description

The invention relates to a method for operating a circulation system and a circulation system, each according to the features of the preambles of the independent claims.

In order to prevent the growth of microbes in cold water networks, DIN EN 806 and VDI guideline 6023 for drinking water installations in buildings require the temperature of the cold drinking water (PWC) in all pipes of the installations to be limited to a maximum of + 25 ° C at all times. According to DIN EN 806-2,3.6, the water temperature for cold water points should not exceed + 25 ° C 30 seconds after an extraction point has been fully opened. Furthermore, in order to avoid stagnation of the water, the cold water installation must be designed in such a way that the drinking water in all pipes of the installation is regularly renewed under normal operating conditions. Similarly, the VDI guideline 6023 also contains the recommendation to keep the temperature of the drinking water below + 25 ° C if possible. It goes without saying that a temperature limitation of the water is often seen as necessary for other water installations as well, for example for installations of industrial water.

• hohe PWC-Temperaturen bereits am Hausanschluss,
• thermische Beeinflussung der Installationsbereiche durch z. B. die Lage und Ausrichtung des Gebäudes oder der Installationsbereiche innerhalb des Gebäudes,
• unzureichende Dämmung der PWC-Rohrleitungen gegen Wärmeeintrag,
• Installation von PWC-Rohrleitungen in Räumen und Technikzentralen mit Wärmequellen, in gemeinsamen Installationsbereichen wie beispielsweise in Schächten, Kanälen, Abhangdecken und Installationswänden mit wärmeabgebenden Medien (z. B. Heizungsrohrleitungen, Trinkwarmwasser (PWH) und Trinkwarmwasser-Zirkulationsanlagen (PWH-C), Zuluft- und Abluftkanäle, Lampen),
• Phasen der Stagnation in vorgenannten Installationsbereichen,
• weit verzweigte PWC-Installationen mit einhergehenden großen
  Anlagenvolumina,
• zu groß dimensionierte PWC-Rohrleitungen.

The occurrence of high PWC temperatures is favored by the sole or joint occurrence of various conditions, including:

• high PWC temperatures at the house connection,
• thermal influence of the installation areas by z. B. the location and orientation of the building or the installation areas within the building,
• Insufficient insulation of the PWC pipes against heat input,
• Installation of PWC pipes in rooms and technical centers with heat sources, in common installation areas such as in shafts, ducts, suspended ceilings and installation walls with heat-emitting media (e.g. heating pipes, domestic hot water (PWH) and domestic hot water circulation systems (PWH-C), supply air and exhaust ducts, lamps),
• Phases of stagnation in the aforementioned installation areas,
• Widely branched PWC installations with accompanying large
  Plant volumes,
• PWC pipelines that are too large.

The preferred method when trying to meet the legal requirements in stagnation phases has so far been the forced flushing of the systems in order to imitate the intended operation in these phases.

In order to make cold drinking water available, various cooled circulation systems have already been proposed for the cold water network.

From the EP 1 626 034 A1 a cooled circulation system is already known in which a controlled addition of a disinfectant to the water is provided.

From the DE 10 2014 013 464 A1 A method is known for operating a circulation system with a heat store, a circulation pump, a control unit and at least two lines and with an otherwise unknown pipe network structure. The strands, which each have a valve that can be adjusted via a motor drive, correspond to temperature sensors that are arranged between the strands in front of each mixing point. The motor drives and / or the circulation pump are connected to the control unit in a wireless or wired manner for data exchange. The control unit is designed to carry out thermal hydraulic balancing and thermal disinfection by limiting the stroke of measured temperatures and / or adjusting the pump output as a function of a difference between an actual temperature value and a target temperature value.

From the DE 20 2015 007 277 U1 is a drinking and service water supply device of a building with a house connection for cold water, which is connected to the public supply network, known. The supply device comprises at least one circulation line which is provided with a pump and leads to at least one consumer. A heat exchanger is provided in the circulation line to extract heat from the water.

In the EP 3 159 457 A1 is also a drinking and industrial water supply device from the DE 20 2015 007 277 U1 known type described, wherein the heat exchanger is formed by a latent heat accumulator and has a motor-operated flushing valve provided in the circulation line, which is connected in terms of control to a control device. The flushing valve is arranged between the latent heat accumulator and an opening of the house connection in the circulation line and is arranged downstream of the latent heat accumulator in the direction of flow.

In the known circulation systems with cooling of the water, it is sometimes not guaranteed at all, or at least not in an effective manner, that the water temperature remains below the desired temperature for all sections and for all times during the operation of the circulation system.

The object of the present invention is therefore to achieve in an effective manner that the water temperature remains below the desired temperature for all sections and for all times during the operation of a circulation system.

The object is achieved according to the invention with the features of the independent patent claims.

The method according to the invention relates to a circulation system with a cooling device with an input port and an output port for cooling water and with a line system with several strands, which have one or more sections with a given heat - coupling with an environment and are connected by means of nodes, with one or more of the lines of the line system are designed as a feed line, at least one individual feed line connected to an extraction point and at least one line designed as a circulation line is connected to the feed line or lines.

The method according to the invention for operating the circulation system is characterized in that, based on a temperature start value T _MA * <T _soll and a volume flow start value V _z * for the first section connected to the output port, a temperature change of the water between the start area and the end area corresponds accordingly a model of the axial temperature change is determined, a temperature change of the water between the start area and the end area for each given further section connected to the first section is determined according to the model of the temperature change, under the boundary condition that the water temperature in the start area of the given section is equal to the water temperature is in the end area of the section to which the given section is connected in the direction of flow of the water and the value T _{a of} the water temperature and the value V _{z of} the volume flow at the output port are selected so that in the end area each section stretch of the circulation system the water temperature T _ME <T _soll and at the inlet port the water temperature T _b <T _soll with T _soll - T _b <θ, where θ> 0 is a predetermined value.

The determination preferably consists of a calculation according to the model of the axial temperature change of the water between the start area and the end area of the section, that is, of the corresponding line section, due to the absorption of heat from the area surrounding the section. Starting with the first section connected to the cooling device, the entire system of sections is successively traversed and the temperature in the entire system is therefore calculated.

According to the invention, in the method, the value T _{a of} the water temperature and the value V _{z of} the volume flow at the output port, in which it is achieved that the water temperature T _ME <T _soll in the end area of each section of the circulation system and the water temperature T at the input port _b <T _soll with T _soll - T _b <θ, where θ> 0 is a predetermined value, determined by modeling the temperature and volume flows of the water circulating in the pipe system, preferably calculated. This is preferably done for a state with a stationary Vz.

The cooling device and, if necessary, a circulation pump of the circulation system are then set in such a way that the water temperature and the volume flow assume the _{values T a} and the value V _{z determined.}

It is proposed according to the invention that a temperature is set at an output port, temperature changes are calculated based thereon and used for modeling in accordance with the specifications of the characterizing part of claim 1.

The advantage of calculating is that no sensor is required to measure something and that influencing variables can be assessed and varied and possibly also made predictions.

Compared to a two-point control and / or a subordinate floor control or string control, the calculation offers the advantage that fewer measuring points are required and the system is less susceptible to vibrations overall.

In comparison to the prior art, the regulation according to the invention is carried out by means of an actuating intervention at the output port, but the regulator design is based on the entire water pipe system with distributed parameters with a calculation of a number of temperatures TME. So basically only one controller and only one temperature setting are required to provide the temperature Ta.

A problem similar to that for a cold water network exists with a hot water network. Only the operating temperatures change, with a storage tank or heater being used instead of a cooling device. The temperatures in the hot water network are between 60 ° C at the storage tank outlet and 55 ° C at the storage tank inlet. In contrast to the cold water network, where it If there is a temperature increase as a result of heat gains from the environment, heat losses lead to a temperature decrease in the hot water network.

• q̇ = spezifischer Wärmestrom in W / m
• Δϑ = ϑ_{Medium,Anfang} - ϑ_Medium,Ende Warmwasser
• Δϑ = ϑ_Medium,Ende - ϑ_{Medium,Anfang} Kaltwasser

The following formula applies both to the temperature drop in a hot water network and to the temperature rise in a cold water network. $$\mathrm{\Delta \vartheta }=\dot{q}\frac{l}{\stackrel{.}{\mathrm{m}}\cdot c_{\mathrm{W.}}}=\dot{q}\frac{l}{\stackrel{.}{\mathrm{V}}\cdot p\cdot c_{\mathrm{W.}}}$$

• q̇ = specific heat flow in W / m
• Δϑ = ϑ _{medium, start} - ϑ _{medium, end of} hot water
• Δϑ = ϑ _{medium, end} - ϑ _{medium, beginning of} cold water

The invention therefore also includes the analogous case of a hot water network, a storage tank or heater being used instead of a cooling device.

Furthermore, the above formula is also valid in a cold water network if the temperature of the water is higher than the ambient temperature.

In general, the invention therefore includes, with corresponding adaptations of the formulas used for calculation according to the model, the case that a heat exchanger is used instead of a cooling device, which can heat or cool the water.

The term “strand” refers to a line consisting of a section or several sections between two nodes, between which there is no other node.
The strands are connected by knots.

The boundary condition that the water temperature in the start area of the given section is equal to the water temperature in the end area of the section to which the given section is connected preferably relates only to the sections of a line.

The temperature and size of the volume flow leaving a node in a subsequent section depends on the temperatures and sizes of the incoming Volume flows from. The invention preferably assumes that these are given by the design of the line system.

The distribution of the volume flows flowing out of a node to the various outgoing lines or sections is preferably assumed in the invention to be given by the design of the line system.

Mixing temperatures in the case of strand unification and the temperatures in the case of strand division are preferably calculated on the basis of a percentage volume flow distribution.

In the method according to the invention, the line system is assumed to be given, it being understood that the line system is designed in accordance with the specifications of DIN 1988-300 for the design of pipe networks, whereby in particular certain nominal widths of the PWC (Potable Water Cold) lines and thermal values Coupling of the circulating water with the environment are prescribed. It goes without saying that, in general, the pipe network designs prescribed or recommended in other countries or regions can also be observed.

The highest value permissible according to the design of the line system is preferably selected as the volume flow start value V _{z *.} This value is reduced until the temperature of the circulating water is close to T _setpoint , since the temperature of the circulating water increases with decreasing volume flow and therefore the temperature at the inlet port rises.

The value T _MA * is preferably varied and the highest value T _{a of} the water temperature is selected, at which the water temperature T _b <T _soll with T _soll - T _b <θ at the inlet port, where θ> 0 is a predetermined value.

The specification T _soll - T _b <θ ensures that the water temperature in the circulation system is not set too cold and that the system is operated in an energetically ineffective manner. Typically θ lies in a range between 1 ° C. and 5 ° C., but can also lie in a different range.

The determination of the temperature change of the water between the beginning and the end of each section can take place in accordance with models that are known per se, for example by means of simulation calculations or also corresponding known formulas.

When carrying out the method according to the invention, the circulation system is preferably operated in a state in which there is no water withdrawal and no water absorption, because in this state a higher heating of the water is to be expected than in a state in which water is withdrawn and thus when using the according to the method determined parameters T _a and V _z a safety margin to a condition with an undesirably high water temperature is guaranteed.

_{The parameters T a} and V _z determined by means of the method are advantageously used to model and operate a given circulation system in which the pipe system is designed in accordance with the statutory provisions with regard to nominal widths and thermal coupling of the circulating water with the environment the legal requirements regarding the temperature of the drinking water in the circulation system are met.

Simulations by the applicant for already existing systems have shown that with the parameters set according to the invention a) the mentioned legal regulations are met and b) a higher energy efficiency of the operation of the system is achieved.

_{The parameters T a} and V _z determined by means of the method are advantageously used to design the cooling device with regard to its cooling capacity for a given circulation system in which the line system is designed in accordance with the statutory provisions with regard to nominal widths and thermal coupling of the circulating water with the environment determine. Furthermore, the design of a circulation pump can be determined with regard to its pumping capacity, if necessary.

The following terms are used in this text with a specific meaning, the definition being based on the DIN EN 806 standard.

A line downstream of an extraction point in the circuit in which water runs from the outlet port of a cooling device back to the inlet port of the cooling device is referred to as a circulation line of the circulation system if no other extraction point is connected to this line.

The term node is used for a line element to which lines are connected. Either at least two volume flows can enter a node and exactly one volume flow can flow out, or precisely one volume flow can flow in and at least two volume flows can flow out. A node corresponds to a branch.

Preferably exactly two volume flows enter and one volume flow into a node of the circulation system, or exactly one volume flow enter and exactly two volume flows exit, as is the case with a T-piece, for example.

In analogy to electrical circuits, Kirchhoff's law applies to the nodes of the circulation system, according to which the sum of the inflowing volume flows is equal to the sum of the outflowing volume flows.

The outgoing volume flows are preferably divided into equally large outgoing volume flows at each node. It goes without saying that other divisions are also possible.

• t_m = Temperatur Mischwasser (°C)
• t_k = Temperatur kälteres Wasser (°C)
• t_w = Temperatur wärmeres Wasser (°C)
• m_m = Masse/Volumen (-strom) Mischwasser (kg; m³; kg/h; m³/h oder %)
• m_k = Masse/Volumen (-strom) Kaltwasser (kg; m³; kg/h; m³/h oder %)
• m_w = Masse/Volumen (-strom) Warmwasser (kg; m³; kg/h; m³/h oder %)

In the case of a node with exactly one outgoing volume flow with different temperatures and exactly one incoming volume flow, it is preferably assumed that the temperature t _m and the mass flow m _{m of} the mixed water of the outgoing volume flow have the following relationship with temperature tk and mass flow mk of the colder or temperature tw and mass flow mw of the warmer flow are related: $$t_m=\frac{t_k\ast m_k+t_w\ast m_w}{m_m}$$

• t _m = temperature of mixed water (° C)
• t _k = temperature of colder water (° C)
• t _w = temperature of warmer water (° C)
• m _m = mass / volume (flow) mixed water (kg; m ³ ; kg / h; m ³ / h or%)
• m _k = mass / volume (flow) cold water (kg; m ³ ; kg / h; m ³ / h or%)
• m _w = mass / volume (flow) hot water (kg; m ³ ; kg / h; m ³ / h or%)

T_Luft

= Temperatur Umgebungsluft(°C)

K_R

= Wärmedurchgangskoeffizient der Rohrleitung (W/(m*K))

m_M

= Massenstrom des Wassers in der Teilstrecke (kg/ s)

c_p,m

= spez. Wärmekapazität des Wassers (J/(kg*K)

V_M

= Volumenstrom des Wassers in der Teilstrecke (m³/s)

P_M

= Dichte des Wassers (kg/m³)

In addition to the length of the section, the following parameters are preferably used to determine the temperature change in the water between the start and end of a section

T _air

= Ambient air temperature (° C)

K _R

= Heat transfer coefficient of the pipe (W / (m * K))

m _M

= Mass flow of water in the section (kg / s)

c _{p, m}

= spec. Heat capacity of water (J / (kg * K)

V _M

= Volume flow of the water in the section (m ³ / s)

P _M

= Density of water (kg / m ³ )

A temperature change of the water between its starting area and its end area can advantageously be determined for each section of the circulation system with a steady volume flow, the water temperature in the end area of a given section being equal to the water temperature in the starting area of the section that is closest to the given section in the direction of flow of the circulating water is selected. Therefore, the temperature of the water in the end area of the respective section can be determined for each section of the circulation system based on the temperature in the initial area.

The temperature of the circulating water can advantageously be determined on the basis of a temperature at the output port with a stationary volume flow for each section, i.e. also a value T _{a of} the water temperature at the output port can be determined as the starting temperature of the section following the output port, in which for the end areas all Sections where the water temperature is T _ME <T _soll .

In a further embodiment of the invention it is provided that the values T _a and V _{z are determined} in an iterative approximation method, in which starting from a temperature start value T _MA * <T _soll and a volume flow start value V _z * for the first section connected to the output port, for each given section the water temperature T _{ME is} calculated in its end area, with the water temperature T _MA 'in the start area of the next connected section equal to the water temperature T _ME in the end area of the given section as selected is.

In a further embodiment of the invention, it is provided that the sections over the length between their starting area and their end area are designed to be axially uniform with regard to their thermal coupling with the environment, and therefore do not change axially. This enables the calculations to be simplified.

$$\mathrm{\epsilon }=\frac{{\mathrm{k}}_{\mathrm{R}}}{{\mathrm{m}}_{\mathrm{M}}\ast {\mathrm{c}}_{\mathrm{pm}}}=\frac{{\mathrm{k}}_{\mathrm{R}}}{{\mathrm{V}}_{\mathrm{M}}\ast {\mathrm{P}}_{\mathrm{M}}\ast {\mathrm{C}}_{\mathrm{pm}}}$$

bestimmt wird, wobei gilt

L

= Länge (m) der uniformen Teilstrecke (T_S1)

T_MA

= Wassertemperatur im Anfangsbereich (°C)

T_ME

= Wassertemperatur im Endbereich (°C)

T_Luft

= Temperatur Umgebungsluft(°C)

k_R

= Wärmedurchgangskoeffizient der Rohrleitung (W/(m*K))

m_M

= Massenstrom des Wassers in der Teilstrecke (kg/ s)

c_p,m

= spez. Wärmekapazität des Wassers (J/(kg*K)

V_M

= Volumenstrom des Wassers in der Teilstrecke (m³/s)

P_M

= Dichte des Wassers (kg/m³)

In a further embodiment of the invention it is provided that the water temperature T _ME in the end region of at least a section of length L is determined by means of the formula $${\mathrm{T}}_{\mathrm{ME}}=\left({\mathrm{T}}_{\mathrm{MA}}-{\mathrm{T}}_{\mathrm{air}}\right)*{\mathrm{e}}^{-\mathrm{\epsilon }\ast \mathrm{L.}}+{\mathrm{T}}_{\mathrm{air}}$$

$$\mathrm{\epsilon }=\frac{{\mathrm{k}}_{\mathrm{R.}}}{{\mathrm{m}}_{\mathrm{M.}}\ast {\mathrm{c}}_{\mathrm{pm}}}=\frac{{\mathrm{k}}_{\mathrm{R.}}}{{\mathrm{V}}_{\mathrm{M.}}\ast {\mathrm{P}}_{\mathrm{M.}}\ast {\mathrm{C.}}_{\mathrm{pm}}}$$

is determined, where applies

L.

= Length (m) of the uniform section (T _S1 )

T _MA

= Water temperature in the initial area (° C)

T _ME

= Water temperature in the end area (° C)

T _air

= Ambient air temperature (° C)

k _R

= Heat transfer coefficient of the pipe (W / (m * K))

m _M

= Mass flow of water in the section (kg / s)

c _{p, m}

= spec. Heat capacity of water (J / (kg * K)

V _M

= Volume flow of the water in the section (m ³ / s)

P _M

= Density of water (kg / m ³ )

This formula allows a good approximation of the temperature change for uniform sections.

bestimmt ist, wobei

1lk_R

= Wärmedurchgangswiderstand Rohrleitung (m∗K/W)

αi

= Wärmeübergangskoeffizient innen (W/(m ²∗K))

1/ΛR

= Wärmedurchlasswiderstand (m∗K/W)

a_a

= Wärmeübergangskoeffizient außen (W/(m²∗K))

d_a

= Außendurchmesser (m)

d_i

= Innendurchmesser (m)

und $$\frac{1}{{\Lambda }_R}=\frac{1}{2\ast \pi }\ast \left(\frac{1}{{\lambda }_r}\ast \mathit{ln}\frac{d_{\mathit{aR}}}{d_{\mathit{iR}}}+\frac{1}{{\lambda }_D}\ast \mathit{ln}\frac{d_{\mathit{aD}}}{d_{\mathit{iD}}}\right)$$

Im folgenden wirdIn a further embodiment of the invention it is provided that the heat transfer coefficient of the sections according to the formula $$\frac{1}{k_{\mathrm{R.}}}=\frac{1}{d_i\ast {\alpha }_i\ast \pi }+\frac{1}{{\Lambda }_{\mathrm{R.}}}+\frac{1}{d_a\ast {\alpha }_a\ast \pi }$$

is determined, where

1 lk _R

= Heat transfer resistance pipe ( m ∗ K / W )

αi

= W Ärm eübergangskoeffizient inside (W / (m ² * K))

1 / ΛR

= Thermal resistance ( m ∗ K / W )

a _a

= Heat transfer coefficient outside ( W / (m ² ∗ K ))

d _a

= Outer diameter ( m )

d _i

= Inside diameter ( m )

and $$\frac{1}{{\Lambda }_{\mathrm{R.}}}=\frac{1}{2\ast \pi }\ast \left(\frac{1}{{\lambda }_r}\ast \mathit{ln}\frac{d_{\mathit{aR}}}{d_{\mathit{iR}}}+\frac{1}{{\lambda }_{\mathrm{D.}}}\ast \mathit{ln}\frac{d_{\mathit{aD}}}{d_{\mathit{iD}}}\right)$$

The following will

In the following, equations 1-4 are used to determine the temperature changes and the heat gain in the water as a result of the temperature difference to the environment.

For this purpose, equation 1 is used for the thermal resistance in equation 2 and thus the thermal resistance is determined. Using the reciprocal of equation 2, the heat transfer coefficient equation 3 is calculated. 1

einer Rohrleitung inkl. Dämmung $$\frac{1}{{\lambda }_{\mathit{ges}}}=\frac{1}{2\cdot \mathrm{\pi }}\cdot \left(\frac{1}{{\mathrm{\lambda }}_{\mathrm{R}}}\cdot \ln \frac{{\mathrm{d}}_{\mathrm{aR}}}{{\mathrm{d}}_{\mathrm{iR}}}+\frac{1}{{\mathrm{\lambda }}_{\mathrm{D}}}\cdot \ln \frac{{\mathrm{d}}_{\mathrm{aD}}}{{\mathrm{d}}_{\mathrm{iD}}}\right)$$

, siehe VDI 2055, 2008Thermal resistance $\frac{1}{{\lambda }_{\mathrm{total}}}$

a pipeline including insulation $$\frac{1}{{\lambda }_{\mathit{total}}}=\frac{1}{2\cdot \mathrm{\pi }}\cdot \left(\frac{1}{{\mathrm{\lambda }}_{\mathrm{R.}}}\cdot \ln \frac{{\mathrm{d}}_{\mathrm{aR}}}{{\mathrm{d}}_{\mathrm{iR}}}+\frac{1}{{\mathrm{\lambda }}_{\mathrm{D.}}}\cdot \ln \frac{{\mathrm{d}}_{\mathrm{aD}}}{{\mathrm{d}}_{\mathrm{iD}}}\right)$$

, see VDI 2055, 2008

der isolierten Rohrleitung $$\frac{1}{{\mathrm{U}}_{\mathrm{R}}}=\frac{1}{{\mathrm{d}}_{\mathrm{iR}}.{\mathrm{a}}_{\mathrm{i}}.\pi }+\frac{1}{{\mathrm{\lambda }}_{\mathit{ges}}}+\frac{1}{{\mathrm{d}}_{\mathrm{aD}}.a_{\mathrm{a}}.\pi }$$

, siehe VDI 2055, 2008 $$\frac{1}{{\mathrm{U}}_{\mathrm{R}}}=\frac{1}{2\cdot \mathrm{\pi }}\cdot \left(\frac{1}{{\mathrm{\lambda }}_{\mathrm{R}}}\cdot \ln \frac{{\mathrm{d}}_{\mathrm{aR}}}{{\mathrm{d}}_{\mathrm{iR}}}+\frac{1}{{\mathrm{\lambda }}_{\mathrm{D}}}\cdot \ln \frac{{\mathrm{d}}_{\mathrm{aD}}}{{\mathrm{d}}_{\mathrm{iD}}}\right)+\frac{1}{{\mathrm{d}}_{\mathrm{aD}}.a_{\mathrm{a}}.\pi }$$

Thermal resistance $\frac{1}{{\mathrm{U}}_{\mathrm{R.}}}$

the insulated pipeline $$\frac{1}{{\mathrm{U}}_{\mathrm{R.}}}=\frac{1}{{\mathrm{d}}_{\mathrm{iR}}.{\mathrm{a}}_{\mathrm{i}}.\pi }+\frac{1}{{\mathrm{\lambda }}_{\mathit{total}}}+\frac{1}{{\mathrm{d}}_{\mathrm{aD}}.a_{\mathrm{a}}.\pi }$$

, see VDI 2055, 2008 $$\frac{1}{{\mathrm{U}}_{\mathrm{R.}}}=\frac{1}{2\cdot \mathrm{\pi }}\cdot \left(\frac{1}{{\mathrm{\lambda }}_{\mathrm{R.}}}\cdot \ln \frac{{\mathrm{d}}_{\mathrm{aR}}}{{\mathrm{d}}_{\mathrm{iR}}}+\frac{1}{{\mathrm{\lambda }}_{\mathrm{D.}}}\cdot \ln \frac{{\mathrm{d}}_{\mathrm{aD}}}{{\mathrm{d}}_{\mathrm{iD}}}\right)+\frac{1}{{\mathrm{d}}_{\mathrm{aD}}.a_{\mathrm{a}}.\pi }$$

Heat transfer coefficient U _{R of} the insulated pipeline $${\mathrm{U}}_{\mathrm{R.}}=\frac{\mathrm{<figure-callout\; id="1"\; label="\pi "\; filenames="imgf0002.png"\; state="\{\{state\}\}">\pi </figure-callout>}}{\frac{1}{2}\cdot \left(\frac{1}{{\mathrm{\lambda }}_{\mathrm{R.}}}\cdot \ln \frac{{\mathrm{d}}_{\mathrm{aR}}}{{\mathrm{d}}_{\mathrm{iR}}}+\frac{1}{{\mathrm{\lambda }}_{\mathrm{D.}}}\cdot \ln \frac{{\mathrm{d}}_{\mathrm{aD}}}{{\mathrm{d}}_{\mathrm{iD}}}\right)+\frac{1}{{\mathrm{d}}_{\mathrm{aD}}\cdot a_{\mathrm{a}}}}$$

The heat transfer coefficient is a central component of equation 4 for calculating a temperature at the end of a section.

$$\mathrm{\Delta \vartheta }={\mathrm{\Delta \vartheta }}_{\mathrm{a}}\left(1-e^{\frac{-U_{\mathrm{R}}\cdot l}{e^{m\cdot c_{\mathrm{W}}}}}\right)$$

, siehe VDI 2055, 2008 $$\mathrm{\Delta \vartheta }={\mathrm{\vartheta }}_{\mathrm{MA}}-{\vartheta }_{\mathrm{ME}}$$

$${\mathrm{\vartheta }}_{\mathrm{MA}}-{\vartheta }_{\mathrm{ME}}=\mathrm{\Delta \vartheta }\mathrm{a}\left(1-e^{\frac{-U_{\mathrm{R}}\cdot l}{m\cdot c_{\mathrm{W}}}}\right)$$

$${\vartheta }_{\mathrm{ME}}=-\mathrm{\Delta \vartheta }\mathrm{a}\left(1-e^{\frac{-U_{\mathrm{R}}\cdot l}{m\cdot c_{\mathrm{W}}}}\right)+{\vartheta }_{\mathrm{MA}}$$

$${\vartheta }_{\mathrm{ME}}=-{\mathrm{\Delta \vartheta }}_{\mathrm{a}}+{\mathrm{\Delta \vartheta }}_{\mathrm{a}}{e}^{\frac{-U_{\mathrm{R}}\cdot l}{m\cdot c_{\mathrm{W}}}}+{\vartheta }_{\mathrm{MA}}$$

einsetzen von Δϑ_a = ϑ_MA - ϑ_Luft und anschließend zusammenfassen. $${\vartheta }_{\mathrm{ME}}={\mathrm{\Delta \vartheta }}_{\mathrm{a}}\cdot e^{\frac{-U_{\mathrm{R}}\cdot l}{m\cdot c_{\mathrm{W}}}}+{\vartheta }_{\mathrm{Luft}}$$

With the help of equation 4, the respective start and end temperatures of the cold water are determined for all relevant sections. The derivation of the formula for the axial heating of water in a pipeline begins with equation 5: $${\vartheta }_{\mathrm{ME}}={\mathrm{\Delta \vartheta }}_{\mathrm{a}}\cdot e^{\frac{-U_{\mathrm{R.}}\cdot l}{m\cdot c_{\mathrm{W.}}}}+{\vartheta }_{\mathrm{air}}$$

$$\mathrm{\Delta \vartheta }={\mathrm{\Delta \vartheta }}_{\mathrm{a}}\left(1-e^{\frac{-U_{\mathrm{R.}}\cdot l}{e^{m\cdot c_{\mathrm{W.}}}}}\right)$$

, see VDI 2055, 2008 $$\mathrm{\Delta \vartheta }={\mathrm{\vartheta }}_{\mathrm{MA}}-{\vartheta }_{\mathrm{ME}}$$

$${\mathrm{\vartheta }}_{\mathrm{MA}}-{\vartheta }_{\mathrm{ME}}=\mathrm{\Delta \vartheta }\mathrm{a}\left(1-e^{\frac{-U_{\mathrm{R.}}\cdot l}{m\cdot c_{\mathrm{W.}}}}\right)$$

$${\vartheta }_{\mathrm{ME}}=-\mathrm{\Delta \vartheta }\mathrm{a}\left(1-e^{\frac{-U_{\mathrm{R.}}\cdot l}{m\cdot c_{\mathrm{W.}}}}\right)+{\vartheta }_{\mathrm{MA}}$$

$${\vartheta }_{\mathrm{ME}}=-{\mathrm{\Delta \vartheta }}_{\mathrm{a}}+{\mathrm{\Delta \vartheta }}_{\mathrm{a}}{e}^{\frac{-U_{\mathrm{R.}}\cdot l}{m\cdot c_{\mathrm{W.}}}}+{\vartheta }_{\mathrm{MA}}$$

insert Δϑ _a = ϑ _MA - ϑ _air and then summarize. $${\vartheta }_{\mathrm{ME}}={\mathrm{\Delta \vartheta }}_{\mathrm{a}}\cdot e^{\frac{-U_{\mathrm{R.}}\cdot l}{m\cdot c_{\mathrm{W.}}}}+{\vartheta }_{\mathrm{air}}$$

An iterative calculation by increasing the volume flow in small parts / steps is used to find the volume flow that operates the cold water installation with a desired / specified spread of, for example, 5 K (15 ° C / 20 ° C).

With the help of this approach, in addition to determining the volume flow of the circulation system, which is in the foreground, a water temperature can also be determined for any point in the pipe network under consideration.

The iterative approximation method is preferably the known Excel target value search; see Excel and VBA: Introduction with practical applications in the natural sciences by Franz Josef Mehr, Maria Teresa Mehr, Wiesbaden 2015, Section 8.1.

According to the invention, key data of the pipeline system including the above-mentioned parameters of the sections are entered in the program and, by means of the target value search, the volume flow V _z at which the target drinking water temperature T _{b is} reached is determined; for example as follows

3.1.1 Properties of water

No. designation Value / MT units MT1 Drinking water inlet temperature outlet port 15.0 ° C MT2 Target drinking water temperature 20.0 ° C MT3 Density of water at 17.5 ° C 998.8 kg / m ³ MT4 Volume flow V _z 0.022 m ³ / h MT5 Specific heat capacity 1.163 Wh / (Kg * K)

3.1.2 Heat transfer coefficients

No. designation W. (W / (m ^{2 ∗} K)) Wi Heat transfer coefficient outside α _a 5 Wa Heat transfer coefficient inside α _i 0

3.1.3 Ambient temperatures

No. designation Temperature UT t _air in ° C UT1 Boiler room 30 ° C UT2 Basement corridor 20 ° C UT3 Manhole 30 ° C UT4 Suspended ceiling in the hallway 33 ° C UT5 Pretext bathroom 26 ° C UT6 Return shaft 26 ° C

3.1.4 Insulation

No. designation Meterial Coefficient of thermal conductivity THERE λ _DA in W / (m ^∗ K) DA1 Rockwool with PVC Boiler room 0.035 DA2 Rockwool laminated with aluminum Basement corridor 0.035 DA3 Rockwool laminated with aluminum Steiger 0.035 DA4 Rockwool laminated with aluminum Ceiling in the hallway 0.035 PA5 Flex El-Conel 24x18 Pretext bathroom 0.032 DA6 With 9 mm insulation in the FB FB bath 0.04

3.1.5 Pipe materials

No. designation Nominal size Wall thickness Coefficient of thermal conductivity THERE mm mm λ _R in W / (m ^∗ K) R1 Viega Raxofix 16 x 2.2 2.2 0.4 R2 Viega Raxofix 20 x 2.8 2.8 0.4 R3 Viega Raxofix 25 x 2.7 2.7 0.4 R4 Viega Raxofix 32 x 3.2 3.2 0.4 R5 Viega Raxofix with insulation 16 x 2.2 2.2 0.35 R6 Viega Raxofix with insulation 20 x 28 2.8 0.35 R7 Viega Raxofix with insulation 25 x 2.7 2.7 0.35 R8 Viega Raxofix with insulation 32 x 3.2 3.2 0.35 R9 Viega Sanpress 15 x 1.0 23 R10 Viega Sanpress 18 x 1.0 1 23 R11 Viega Sanpress 22 x 1.2 1.2 23 R12 Viega Sanpress 28 x 1.2 1.2 23 R13 Viega Sanpress 35 x 1.5 1.5 23 R14 Viega Sanpress 42 x 1.5 1.5 23 R15 Viega Sanpress 54 x 1.5 1.5 23 R16 Viega Sanpress 64 x 2 2 23

In this example, the calculated volume flow V _z , at which _{a target temperature Tb of 20 ° is reached at an inlet temperature T a} of 15 ° C., is indicated in line MT4.

In a further embodiment of the invention it is provided that a circulation pump is integrated into the circulation system, with which a desired volume flow can be set.

It goes without saying that several cooling devices and / or circulation pumps can also be provided.

In the following, embodiments with line structures are described, as they are typically used in drinking water installations in buildings.

A connection line is a line between a supply line and a drinking water installation or the circulation system.

A consumption line is a line that supplies water from the main shut-off valve to the tapping connections and, if necessary, feeds it into apparatus. A collective feed line is a horizontal consumption line between the main shut-off valve and a riser. A rising (falling) line leads from floor to floor and from which the floor lines or individual feed lines branch off. A floor line is the line that branches off from the rising (falling) pipe within a floor and from which individual feed lines branch off. A single feed line is the line leading to an extraction point.

In one embodiment of the invention it is provided that at least one feed line is connected to at least one ring line.

In a further embodiment of the invention it is provided that at least one branch of the circulation line branches off from the at least one feed line.

In a further embodiment of the invention it is provided that at least one branch of the at least one circulation line branches off from the at least one ring line.

In a further embodiment of the invention it is provided that the at least one feed line comprises at least one riser and / or one floor line.

In a further embodiment of the invention it is provided that the at least one feed line comprises a collective feed line which is connected to a connection to a water supply network.

In a further embodiment of the invention it is provided that the connection is connected to at least one connection line and / or at least one consumption line.

In a further embodiment of the invention it is provided that at least one static or dynamic flow divider is arranged in the at least one feed line and / or the at least one ring line, with which a tapping point for water is preferably connected. A percentage distribution of the volume flows is preferably made 95% at the outlet and 5% at the passage.

In a further embodiment of the invention it is provided that by means of the cooling device for cooling the circulating water, thermal energy is transferred from the circulating water to another material flow, preferably by means of a heat exchanger, thereby optimizing the cooling process suitable choice of the other material flow, for example propane, and a reduction in the energy required to operate the cooling device can be achieved.

In a further embodiment of the invention it is provided that the cooling device is thermally coupled to a cold generator, preferably a heat pump, a cold water set or a cold supply network, whereby a reduction in the energy required for the cooling process can also be achieved.

In a further embodiment of the invention, the determination of a consumption characteristic curve of the circulation pump as a function of the conveyed volume flow of the circulation pump and the determination of a consumption characteristic curve of the cooling device as a function of a water temperature at the output port and the setting of a volume flow rate V _z and a water temperature T _a at the output port so that the power consumption of the circulation pump and cooling device assumes a relative or absolute minimum value, which improves the energy efficiency of the method.

In a further embodiment of the invention is advantageously provided that the temperature T is a value of 20 ° C +/- _to selected 5 ° C and selected for the water temperature T _a at the output port a value of 15 ° C +/- 5 ° C becomes.

In a further embodiment of the invention it is provided that at least a section of the line system is designed as an external circulation line, since external circulation lines are mostly built into already existing circulation systems.

In a further embodiment of the invention it is provided that at least one section is designed as an inliner circulation line, since these are often built into newer or new circulation systems.

Further advantages emerge from the following description of the drawings.

In the drawings, exemplary embodiments are shown in the description. The drawing, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

Figur 1:

in schematischer Darstellung ein erfindungsgemäßes Zirkulationssystem

Figur 2:

eine weitere Ausführungsform eines erfindungsgemäßes Zirkulationssystem

Figur 3:

eine weitere Ausführungsform eines erfindungsgemäßes Zirkulationssystem, wobei ein weiterer Wärmetauscher vorgesehen ist

Figur 4:

eine weitere Ausführungsform eines erfindungsgemäßes Zirkulationssystem

Figur 5:

eine weitere Ausführungsform eines erfindungsgemäßes Zirkulationssystem

Figur 6:

eine weitere Ausführungsform eines erfindungsgemäßes Zirkulationssystem

Figur 7:

eine weitere Ausführungsform eines erfindungsgemäßes Zirkulationssystem

Figur 8:

eine weitere Ausführungsform eines erfindungsgemäßes Zirkulationssystem

It shows by way of example:

Figure 1:

a schematic representation of a circulation system according to the invention

Figure 2:

another embodiment of a circulation system according to the invention

Figure 3:

a further embodiment of a circulation system according to the invention, wherein a further heat exchanger is provided

Figure 4:

another embodiment of a circulation system according to the invention

Figure 5:

another embodiment of a circulation system according to the invention

Figure 6:

another embodiment of a circulation system according to the invention

Figure 7:

another embodiment of a circulation system according to the invention

Figure 8:

another embodiment of a circulation system according to the invention

The ones in the Figures 1 to 8 The circulation systems shown are only examples, without the invention being restricted to these systems. In all of the systems shown, exactly two volume flows enter a node and one volume flow exit, or exactly one volume flow enters and exactly two volume flows exit, as is the case with a T-piece, for example. However, the invention is not restricted to systems with such nodes. In principle, all the lines shown between nodes and between nodes and input port as well as nodes and output port consist of one or more sections, as defined above.

Components of the same type are provided with the same reference symbols.

The in Figure 1 The circulation system shown is a node K1 is connected to an output port 12b of a cooling device 12 via a flow line 4a. The cooling device 12 has connections on the refrigeration circuit side and a pump 13 on the refrigeration circuit side.

At node K1, a branch to a collecting line 4, a connection line to a connection 1 to a water supply network and a consumption line 3 is provided, the latter and the connection line not belonging to the circulation system. There is therefore no volume flow division at node K1.

The collective feed line 4 is connected to a riser line 5 which opens into a node K2. The node K2 branches into a floor line 6 and a riser 5, which opens into a node K3 and at which a branch to a floor line 6 and a riser 5 takes place, is connected to a floor line 6 which opens into a node K4. The node K2 is connected to a node K6 via a floor line 6. The node K3 is connected to a node K5 via a floor line 6.

Two sections TS1 and TS2 explicitly identified as such are connected via the node K4, TS1 section of the floor line 6 and TS2 representing a circulation line.

At node K4, there is also a branch via a single feed line 7 to an extraction point 9. For the sake of simplicity, the individual feed lines and tapping points connected to nodes K2 and K3 are not provided with reference symbols. Since the circulation system according to the invention for carrying out the method according to the invention is operated in a state in which there is no water withdrawal, those nodes that are assigned to withdrawal points are excluded from consideration in the following and, with the exception of node K4, are accordingly not shown in the drawings Provided with reference numerals.

The section TS2 is connected to a vertical circulation line 10a which opens into the node K5. The node K5 is connected to a circulation line 10a which opens into the node K6. The node K6 is connected to a vertical circulation line 10a, which is connected to a horizontal circulation line 10a, which in turn is connected to the circulation pump 10b via a vertical circulation line.

This in Figure 2 The circulation system shown has a structure analogous to that of the Figure 1 , however, 6 ring lines are provided in the floor lines, whereby for simplification only in the uppermost in Figure 2 a reference numeral 8 is used. The ring line 8 is assigned an optional flow divider 8a. Ring lines are assigned to nodes K21 to K32. It goes without saying that systems in which only one ring line is present are also encompassed by the invention.

In Figure 3 a further system with nodes K31 to K34 is shown, in which, however, the circulation lines 10a opening into the nodes K34 and K35 are routed parallel to the floor lines 6 emanating from the nodes K32 and K33.

Furthermore, an optional decentralized cooling device 14 with an input port 14a and an output port 14b is arranged in the uppermost floor line 6, connections of a cold-side circuit and a corresponding pump not being shown to simplify the illustration.

Similarly, further decentralized cooling devices can be arranged in the other floor lines.

In a further embodiment analogous to that Figure 3 the heat exchanger 12 can be omitted, in which case one cooling device 14 or several cooling devices 14 are mandatory.

Analogous to the embodiment of Figure 3 can cooling devices in the risers 5 or the floor line of the embodiments of Figures 1 , 2 and 4 to 8 can be provided.

Figure 4 shows a system with nodes K41 to K51 as in FIG Figure 3 , however, ring lines 8 are provided in the floor lines.

Figure 5 shows a system with nodes K51 to K55, in which circulation lines 10 are routed parallel to the risers 5 connected to nodes K52, K53.

Figure 6 shows a system with the nodes K61 to K69b, with ring lines being provided between the nodes K63, K64, K66, K67 and K68, K69.

Figure 7 Figure 3 shows a system with nodes K71 to K75, with risers 5 connected to nodes K72 and K73.

Figure 8 shows a system with nodes K81 to K89b analogous to FIG Figure 7 but with ring lines arranged between nodes K89a, K89b, K88, K89 as well as K84 and K85.

The ones in the final artwork under Figures 1 , 3rd , 5 , 7th The embodiments shown can also circulate only partial areas. So the sections can also z. B. represent installations in apartments that are not allowed to circulate due to various requirements (billing of water consumption). An exchange of water to maintain the desired temperature would be possible here using automatic dishwashers.

The inventive method is used in the systems of Figures 1 to 8 executed in the manner described above, based on a temperature start value T _MA * <T _soll and a volume flow start value V _z * for the first section connected to the output port (12b) a temperature change of the water between the start area and end area according to a model the temperature change is determined.

Furthermore, a temperature change of the water between the start area and the end area is calculated for each given further section according to the model of the temperature change determined, under the boundary condition that the water temperature in the start area of the given section is equal to the water temperature in the end area of the section to which the given section is connected.

$$\mathrm{\epsilon }=\frac{{\mathrm{k}}_{\mathrm{R}}}{{\mathrm{m}}_{\mathrm{M}}\ast {\mathrm{c}}_{\mathrm{pm}}}=\frac{{\mathrm{k}}_{\mathrm{R}}}{{\mathrm{V}}_{\mathrm{M}}\ast {\mathrm{P}}_{\mathrm{M}}\ast {\mathrm{C}}_{\mathrm{pm}}}$$

errechnet.The above-described model of the axial temperature change is preferably used, according to which the water temperature T _ME in the end region of a section of length L is determined by means of the formula $${\mathrm{T}}_{\mathrm{ME}}=\left({\mathrm{T}}_{\mathrm{MA}}-{\mathrm{T}}_{\mathrm{air}}\right)*{\mathrm{e}}^{-\mathrm{\epsilon }\ast \mathrm{L.}}+{\mathrm{T}}_{\mathrm{air}}$$

$$\mathrm{\epsilon }=\frac{{\mathrm{k}}_{\mathrm{R.}}}{{\mathrm{m}}_{\mathrm{M.}}\ast {\mathrm{c}}_{\mathrm{pm}}}=\frac{{\mathrm{k}}_{\mathrm{R.}}}{{\mathrm{V}}_{\mathrm{M.}}\ast {\mathrm{P}}_{\mathrm{M.}}\ast {\mathrm{C.}}_{\mathrm{pm}}}$$

calculated.

The value T _{a of} the water temperature and the value V _{z of} the volume flow at the output port 12b are selected in such a way that the water temperature T _ME <T _soll is in the end area of each section of the circulation system and the water temperature T _b <T _soll with T at the inlet port 12a _should - T _b <θ, where θ> 0 is a predetermined value.

It goes without saying that the circulation pump 10b is not always operated with a constant volume flow, that is to say regardless of whether the port inlet temperature 12a has exactly the set value or is even below it.

Should the port inlet temperature 12a for various reasons z. B. at 17 ° C, z. B. a maximum of 20 ° C are specified, the delivery volume flow of the circulation pump 10b could be reduced. This can take place automatically, for example, in a temperature-controlled manner. The result would be energy savings.

In such a case, the delivery volume flow of the pump 13 can also be reduced in a temperature-controlled manner.

(m K)W Wärmedurchlasswiderstand $$\frac{1}{{\mathrm{U}}_{\mathrm{R}}}$$

(m K)W Wärmedurchgangswiderstand U_R W(m K) Wärmedurchg angskoeffizient für das Rohr Wärmeverlust eines 1 m langen gedämmten Warmwasserrohres bei einer Temperaturdifferenz zwischen dem Wasser und der Luft von 1 K d_a mm Rohraußendurchmesser Außendurchmesser einer Warmwasserleitung D mm Rohraußendurchmesser Außendurchmesser einer gedämmten Warmwasserleitung l m Rohrleitungslänge Länge einer Teilstrecke ϑ_Luft °C Luft-/ Umgebungstemperatur Δϑ _α K Anfangstemperaturunterschied Temperaturunterscheid zwischen Umgebung und Medium am Beginn einer Teilstrecke ϑ_MA °C Mediumstemperatur Anfang Temperatur eines Mediums am Anfang einer Teilstrecke ϑ_ME °C Mediumstemperatur Ende Temperatur eines Mediums am Ende einer Teilstrecke Should the port inlet temperature for various reasons z. For example, if the temperature is 17 ° C (e.g. a maximum of 20 ° C is specified), the flow temperature in the refrigeration circuit could also be adjusted. The result would be energy savings. Table 1 symbol unit designation Explanation C _W kJ ( kg K ) specific heat capacity of water Heat for heating 1 kg of water by 1 K (4.19 kJ / (kg K)) ρ kg / m ³ Density of water Quotient of the mass and volume of the water at a given temperature α _a W ( m ² K ) external heat transfer coefficient Heat loss over a 1 m ² area with a temperature difference between surface and air of 1 K λ _D W ( m K ) Thermal conductivity of the insulation λ _R W ( m K ) Thermal conductivity of the pipeline λ _total W ( m K) Thermal conductivity of a component here a pipeline including multilayer insulation $$\frac{1}{{\lambda }_{\mathrm{total}}}$$

( m K ) W Thermal resistance $$\frac{1}{{\mathrm{U}}_{\mathrm{R.}}}$$

( m K ) W Thermal resistance U _R W ( m K ) Heat transfer coefficient for the pipe Heat loss from a 1 m long insulated hot water pipe with a temperature difference between the water and the air of 1 K d _a mm Outer pipe diameter Outside diameter of a hot water pipe D. mm Outer pipe diameter Outside diameter of an insulated hot water pipe l m Pipe length Length of a section ϑ _air ° C Air / ambient temperature Δϑ _α K Initial temperature difference Temperature difference between the environment and the medium at the beginning of a section ϑ _MA ° C Medium temperature start Temperature of a medium at the beginning of a section ϑ _ME ° C Medium temperature end Temperature of a medium at the end of a section

List of reference symbols

1

Connection to a water supply network

2

Connecting cable

3

Consumption line

4th

Collective feed line

5

Rise (fall) lead

6th

Floor management

7th

Single lead

8th

Ring line

8a

static or dynamic flow division

9

Tapping point

10

Circulation system

10a

Circulation line

10b

Circulation pump

12th

Cooling device

12a

Input port

12b

Output port

14th

Heat exchanger

14a

Input port

14b

Output port

Claims (27)

1. Method for operating a circulation system (10) having a cooling device (12, 14) with an input port (12a, 14a) and an output port (12b, 14b) for the cooling of water and having a pipeline system with multiple branches comprising one or more partial sections with given thermal coupling to the surroundings and being connected by means of nodes, wherein one or more of the lines of the pipeline system are configured as a flow pipe (4, 5, 6), at least one as a single supply line (7) connected to a tapping point (9), and at least one line configured as a circulation conduit (10a) connected to the flow pipe or pipes (4, 5, 6),
   with the steps

   - setting a water temperature at the output port (12b, 14b) to a value T_a by means of the cooling device (12, 14)

   - setting a volume flow at the input port (12a) to a value V_z
   characterized by the following steps

   - determining, in particular calculating, a temperature change of the water between the initial region and the end region according to a model of the axial temperature change for the first partial section connected to the output port (12b, 14b), starting from a temperature start value T_MA* < T_soll and a volume flow start value V_z*,

   - determining, in particular calculating, a temperature change of the water between the initial region and the end region for each further given partial section according to the model of the temperature change, under the boundary condition that the water temperature in the initial region of the given partial section is equal to the water temperature in the end region of the partial section to which the given partial section is connected, and

   - selecting the value T_a of the water temperature and the value V_z of the volume flow at the output port (12b, 14b) such that, in the end region of each partial section, the water temperature is T_ME < T_soll and at the input port (12a, 14b) the water temperature is set at T_b < T_soll with T_soll - T_b < θ, where θ>0 is a given value.
2. The method according to claim 1, characterized in that the values T_a and V_z are determined in an iterative approximation procedure, wherein the temperature change of the water between the initial region and the end region is calculated starting from a temperature start value T_MA* < T_soll and a volume flow start value V_z* for the first partial section connected to the output port (12b, 14b) for each further given partial section under the boundary condition that the water temperature in the initial region of the given partial section is equal to the water temperature in the end region of the partial section to which the given partial section is connected.
3. The method according to claim 1 or 2, characterized in that the partial sections are designed uniformly in regard to their thermal coupling to the surroundings along the length between their initial region and their end region.
4. The method according to claim 3, characterized in that the water temperature T_ME in the end region of at least one partial section with length L is determined by means of the formula $${\mathrm{T}}_{\mathrm{ME}}=\left({\mathrm{T}}_{\mathrm{MA}}-{\mathrm{T}}_{\mathrm{Luft}}\right)*{\mathrm{e}}^{-\mathrm{\epsilon }\ast \mathrm{L}}+{\mathrm{T}}_{\mathrm{Luft}}$$

   

   $$\mathrm{\epsilon }=\frac{{\mathrm{k}}_{\mathrm{R}}}{{\mathrm{m}}_{\mathrm{M}}\ast {\mathrm{c}}_{\mathrm{pm}}}=\frac{{\mathrm{k}}_{\mathrm{R}}}{{\mathrm{V}}_{\mathrm{M}}\ast {\mathrm{P}}_{\mathrm{M}}\ast {\mathrm{C}}_{\mathrm{pm}}}$$

   

   where

   L = the length of the uniform partial section (T_s1) (m)

   T_MA = the water temperature in the initial region (°C)

   T_ME = the water temperature in the end region (°C)

   T_Luft = the temperature of the ambient air(°C)

   k_R = the heat transfer coefficient of the pipeline (W/(m*K))

   m_M = the mass flow of the water in the partial section (kg/ s)

   c_p,m = the spec. heat capacity of the water (J/(kg*K)

   V_M = the volume flow of the water in the partial section (m³/s)

   p_M = the density of the water (kg/m³)
5. The method according to claim 4, characterized in that the heat transfer coefficient of the partial sections is determined by the formula $$\frac{1}{k_R}=\frac{1}{d_i\ast {\alpha }_i\ast \pi }+\frac{1}{{\Lambda }_R}+\frac{1}{d_a\ast {\alpha }_a\ast \pi }$$

   

   where

   1/k_R = the heat transmission resistance of the pipeline (m * K/W)

   ot i = the inward heat transfer coefficient (W/(m² * K))

   1/ΛR = the thermal resistance (m * K/W)

   α_a = the outward heat transfer coefficient (W/(m² * K))

   d_a = the outer diameter (m)

   d_i = the inner diameter (m)
   and $$\frac{1}{{\Lambda }_R}=\frac{1}{2\ast \pi }\ast \left(\frac{1}{{\lambda }_r}\ast \mathit{ln}\frac{d_{\mathit{aR}}}{d_{\mathit{iR}}}+\frac{1}{{\lambda }_D}\ast \mathit{ln}\frac{d_{\mathit{aD}}}{d_{\mathit{iD}}}\right)$$

   
6. The method according to one of the preceding claims, characterized in that a circulation pump (10b) is integrated in the circulation system (10).
7. The method according to one of the preceding claims, characterized in that the cooling device (12, 14) is used to cool the circulating water by transferring thermal energy from the circulating water to another material flow, preferably by means of a heat transfer agent.
8. The method according to claim 7, characterized in that the cooling device (12, 14) is thermally coupled to a cold generator, preferably a heat pump, a water chiller or a cold supply network.
9. The method according to one of claims 6 to 8, characterized by

   - determining a consumer characteristic of the circulation pump (10b) in dependence on a delivered volume flow of the circulation pump (10b)

   - determining a consumer characteristic of the cooling device (12, 14) in dependence on a water temperature at the output port (12b, 14b)

   - setting a volume flow V_z and a water temperature T_a at the output port (12b, 14b) such that the power consumption of the circulation pump (10b) and the cooling device (12, 14) takes on a relative or absolute minimum value.
10. The method according to one of the preceding claims, characterized in that a value of 20° C +/- 5° C is chosen for the temperature T_soll and a value of 15° C +/-5° C is chosen for the water temperature T_a at the output port (12b, 14b).
11. A circulation system having a cooling device (12, 14) with an input port (12a, 14a) and an output port (12b, 14b) for the cooling of water and having a pipeline system with multiple branches comprising one or more partial sections with given thermal coupling to the surroundings and being connected by means of nodes,

    - wherein, for a given apportionment of the volume flows emerging from the nodes, a mixed water temperature is determinable from the volume flows emerging from the nodes in dependence on the volume flows entering the nodes,

    - wherein one or more of the lines of the pipeline system are configured as a flow pipe (4, 5, 6), at least one as a single supply line (7) connected to a tapping point (9), and at least one line configured as a circulation conduit (10a) connected to the flow pipe or pipes (4, 5, 6),
    having

    - means of setting the water temperature at the output port (12b, 14b) to a value T_a by means of the cooling device (12, 14)

    - means of setting a stationary volume flow of circulating water at the input port (12a, 14a) to a value V_z
    characterized by

    - device means for determining a temperature change of the water between the initial region and the end region of each partial section under the boundary condition that the water temperature in the end region of a given partial section is chosen equal to the water temperature in the initial region of the partial section connected to the given partial section in the flow direction of the circulating water and

    - device means for selecting the value T_a of the water temperature and the value V_z of the volume flow at the output port (12b, 14b) such that, in the end region of each partial section, the water temperature is T_ME < T_soll and at the input port (12a, 14b) the water temperature is set at T_b < T_soll with T_soll - T_b < θ, where θ>0 is a given value.
12. The circulation system according to claim 11, characterized in that device means are provided for determining the values T_a and V_z in an iterative approximation procedure, wherein the water temperature T_ME is calculated for each given partial section in its end region, starting from a temperature start value T_MA* < T_soll and a volume flow start value V_z* for the first partial section connected to the output port (12b), wherein the water temperature T_MA' in the initial region of the next attached partial section is chosen equal to the water temperature TME in the end region of the given partial section.
13. The circulation system according to claims 11 to 13, characterized in that the partial sections are designed uniformly in regard to their thermal coupling to the surroundings along the length between their initial region and their end region.
14. The circulation system according to claims 11 to 13, characterized in that a circulation pump (7) is integrated in the circulation system (10).
15. The circulation system according to one of the preceding claims, characterized in that at least one flow pipe (4, 5, 6) is connected to at least one loop line (8).
16. The circulation system according to one of the preceding claims, characterized in that at least one line of the circulation conduit (10a) departs from the at least one flow pipe (4, 5, 6).
17. The circulation system according to one of the preceding claims, characterized in that at least one line of the at least one circulation conduit (10a) departs from the at least one loop line (8).
18. The circulation system according to one of the preceding claims, characterized in that the at least one flow pipe (4, 5, 6) comprises at least one riser line (5) and/or a building floor line (6).
19. The circulation system according to one of the preceding claims, characterized in that the at least one flow pipe (4, 5, 6) comprises a collective feed line (4), which is connected by a junction (1) to a water supply network.
20. The circulation system according to one of the preceding claims, characterized in that the junction (1) is connected to at least one connection line (2) and/or at least one consumer line (3).
21. The circulation system according to one of the preceding claims, characterized in that at least one static or dynamic flow divider (8a) is arranged in the at least one flow pipe (4, 5, 6) and/or the at least one loop line (8).
22. The circulation system according to one of the preceding claims, characterized in that the cooling device (12, 14) is used to transfer thermal energy from the circulating water to another material flow, preferably by means of a heat transfer agent.
23. The circulation system according to claim 22, characterized in that the cooling device (12, 14) is thermally coupled to a cold generator, preferably a heat pump, a water chiller or a cold supply network.
24. The circulation system according to claim 23, characterized in that at least one partial section of the pipeline system is designed as an outer circulation conduit.
25. The circulation system according to claim 24, characterized in that at least one partial section is designed as an inliner circulation conduit.
26. The circulation system according to one of claims 11 to 25, characterized in that the cooling device (12) is connected by its output port (12b) to a flow pipe (4a) and by its input port (12a) to a vertical circulation conduit.
27. The circulation system according to one of claims 11 to 26, characterized in that the cooling device (14) is integrated in a riser line (5) and/or a building floor line (6).

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