METHOD FOR OPERATING A CIRCULATION SYSTEM, AND CIRCULATION SYSTEM

Abstract

The invention relates to a method for operating a circulation system comprising a cooling device with an input port and an output port for cooling water. The invention also relates to a circulation system for implementing said method.

Claims

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.sub.a by means of the cooling device (12, 14) setting a volume flow at the input port (12a) to a value V.sub.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.sub.MA*<T.sub.soll and a volume flow start value V.sub.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.sub.a of the water temperature and the value V.sub.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.sub.ME<T.sub.soll and at the input port (12a, 14b) the water temperature is set at T.sub.b<T.sub.soll with T.sub.soll−T.sub.b<θ, where θ>0 is a given value.

2. The method according to claim 1, characterized in that the values T.sub.a and V.sub.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.sub.MA*<T.sub.soll and a volume flow start value V.sub.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.sub.ME in the end region of at least one partial section with length L is determined by means of the formula $T_{\mathrm{ME}}={\left(T_{\mathrm{MA}}-T_{\mathrm{Luft}}\right)}^{*}{e}^{-\epsilon *L}+T_{\mathrm{Luft}}\epsilon =\frac{k_R}{m_M*c_{pm}}=\frac{k_R}{V_M*P_M*C_{pm}}$ where L=the length of the uniform partial section (T.sub.S1) (m) T.sub.MA=the water temperature in the initial region (° C.) T.sub.ME=the water temperature in the end region (° C.) T.sub.Luft=the temperature of the ambient air (° C.) k.sub.R=the heat transfer coefficient of the pipeline (W/(m*K)) m.sub.M=the mass flow of the water in the partial section (kg/s) c.sub.p,m=the spec. heat capacity of the water (J/(kg*K) V.sub.M=the volume flow of the water in the partial section (m.sup.3/s) P.sub.M=the density of the water (kg/m.sup.3)

5. The method according to claim 4, characterized in that the heat transfer coefficient of the partial sections is determined by the formula $\frac{1}{k_R}=\frac{1}{d_i*{\alpha }_i*\pi }+\frac{1}{{\Lambda }_R}+\frac{1}{d_a*{\alpha }_a*\pi }$ where 1/k.sub.R=the heat transmission resistance of the pipeline (m*K/W) αi=the inward heat transfer coefficient (W/(m.sup.2*K)) 1/ΛR=the thermal resistance (m*K/W) a.sub.a=the outward heat transfer coefficient (W/(m.sup.2*K)) d.sub.a=the outer diameter (m) d.sub.i=the inner diameter (m) and $\frac{1}{{\Lambda }_R}=\frac{1}{2*\pi }*\left(\frac{1}{{\lambda }_r}*\ln \frac{d_{aR}}{d_{\mathrm{iR}}}+\frac{1}{{\lambda }_D}*\ln \frac{d_{aD}}{d_{\mathrm{iD}}}\right)$

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.sub.z and a water temperature T.sub.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.sub.soll and a value of 15° C.+/−5° C. is chosen for the water temperature T.sub.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.sub.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.sub.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.sub.a of the water temperature and the value V.sub.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.sub.ME<T.sub.soll and at the input port (12a, 14b) the water temperature is set at T.sub.b<T.sub.soll with T.sub.soll−T.sub.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.sub.a and V.sub.z in an iterative approximation procedure, wherein the water temperature T.sub.ME is calculated for each given partial section in its end region, starting from a temperature start value T.sub.MA*<T.sub.soll and a volume flow start value V.sub.z* for the first partial section connected to the output port (12b), wherein the water temperature T.sub.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).

Description

[0119] There are shown, as an example:

[0120] FIG. 1: in schematic representation, a circulation system according to the invention

[0121] FIG. 2: a further embodiment of a circulation system according to the invention

[0122] FIG. 3: a further embodiment of a circulation system according to the invention, in which a further heat exchanger is provided

[0123] FIG. 4: a further embodiment of a circulation system according to the invention

[0124] FIG. 5: a further embodiment of a circulation system according to the invention

[0125] FIG. 6: a further embodiment of a circulation system according to the invention

[0126] FIG. 7: a further embodiment of a circulation system according to the invention

[0127] FIG. 8: a further embodiment of a circulation system according to the invention

[0128] The circulation systems represented in FIGS. 1 to 8 are merely examples, the invention not being limited to these systems. In all the systems shown, exactly two volume flows enter a node and one volume flow departs from it, or exactly one volume flow enters and exactly two volume flows depart from it, as in the case of a T-piece. However, the invention is not limited to systems with such nodes. Basically, all of the lines represented between nodes and between nodes and input port, as well as nodes and output port, may consist of one or more partial sections, as defined above.

[0129] Similar components are given the same reference numbers.

[0130] In the circulation system represented in FIG. 1, one node K1 is connected across a flow pipe 4a to an output port 12b of a cooling device 12. The cooling device 12 has connections on the refrigeration side and a refrigeration pump 13.

[0131] At the node K1 there is provided a branching point to a collective line 4, a connection line to a junction 1 at a water supply network and a consumer line 3, the latter and the connection line not being part of the circulation system. Therefore, no volume flow apportioning occurs at the node K1.

[0132] The collective feed line 4 is connected to a riser pipe 5, which empties into a node K2. The node K2 branches into a building floor line 6 and a riser pipe 5, which empties into a node K3 and at which there occurs a branching to a building floor line 6 and a riser pipe 5, [which] is connected to a building floor line 6, which empties into a node K4. The node K2 is connected by a building floor line 6 to a node K6. The node K3 is connected by a building floor line 6 to a node K5.

[0133] Two partial sections TS1 and TS2, explicitly characterized as such, are connected across the node K4, TS1 representing a partial section of the building floor line 6 and TS2 representing a circulation conduit.

[0134] Moreover, at node K4 there occurs a branching across a single supply line 7 to a tapping point 9. To simplify matters, the single supply lines and tapping points connected to the nodes K2 and K3 are not given reference numbers. Since the circulation system according to the invention is operated in order to carry out the method according to the invention in a state in which no water removal occurs, the nodes which are coordinated with the tapping points are not considered in the following and, accordingly, not given reference numbers in the drawings, except for node K4.

[0135] The partial section TS2 is connected to a vertical circulation conduit 10a, which empties into the node K5. The node K5 is connected to a circulation conduit 10a, which empties into the node K6. The node K6 is connected to a vertical circulation conduit 10a, which is connected to a horizontal circulation conduit 10a, which in turn is connected across a vertical circulation conduit to the circulation pump 10b.

[0136] The circulation system represented in FIG. 2 has a similar structure to the system of FIG. 1, but loop lines are provided in the building floor lines 6, and to simplify matters a reference number 8 is used only for the uppermost loop line represented in FIG. 2. The loop line 8 is coordinated with an optional flow divider 8a. Loop lines are coordinated with nodes K21 to K32. It is understood that such systems in which only one loop line is present are also covered by the invention.

[0137] FIG. 3 shows another system with nodes K31 to K34, but here the circulation conduits 10a emptying into the nodes K34 and K35 are led in parallel with the building floor lines 6 departing from the nodes K32 and K33.

[0138] Moreover, an optional decentralized cooling device 14 with an input port 14a and an output port 14b is arranged in the uppermost building floor line 6, while to simplify the representation the existing junctions of a cold-side circuit and a corresponding pump are not shown.

[0139] Similarly, further decentralized cooling devices can be arranged in the other building floor lines.

[0140] In another embodiment similar to FIG. 3, the heat exchanger 12 may be omitted; in this case, one cooling device 14 or multiple cooling devices 14 are necessary.

[0141] Similar to the embodiment of FIG. 3, cooling devices can be provided in the riser pipes 5 and the building floor line of the embodiments of FIGS. 1, 2 and 4 to 8.

[0142] FIG. 4 shows a system with nodes K41 to K51 as in FIG. 3, but loop lines 8 are provided in the building floor lines.

[0143] FIG. 5 shows a system with nodes K51 to K55, in which circulation conduits 10 are led in parallel with the riser pipes 5 connected to the nodes K52, K53.

[0144] FIG. 6 shows a system with the nodes K61 to K69b, where loop lines are provided between the nodes K63, K64, K66, K67 and K68, K69.

[0145] FIG. 7 shows a system with the nodes K71 to K75, where riser pipes 5 are connected to the nodes K72 and K73.

[0146] FIG. 8 shows a system with nodes K81 to K89b similar to FIG. 7, but with loop lines arranged between the nodes K89a, K89b, K88, K89 and K84 and K85.

[0147] The embodiments represented in the clean drawings under FIGS. 1, 3, 5, 7 can also allow only partial regions to have a circulation. Thus, the partial sections may also represent installations in dwellings, for example, which are not permitted to circulate together on account of different requirements (account metering of the water consumption). A water exchanging to maintain the desired temperature could be possible here with automatic flushing.

[0148] The method according to the invention is implemented in the systems of FIGS. 1 to 8 in the above-described manner starting from a temperature start value T.sub.MA*<T.sub.soll and a volume flow start value V.sub.z* for the first partial section connected to the output port (12b), a temperature change of the water between the initial region and the end region is determined according to a model of the temperature change.

[0149] Moreover, a temperature change of the water between the initial region and the end region for each further given partial section is determined 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.

[0150] Preferably, one uses the above-described model of the axial temperature change, according to which the water temperature T.sub.ME in the end region of a partial section of length L is calculated by the formula

[00013]$T_{\mathrm{ME}}={\left(T_{\mathrm{MA}}-T_{\mathrm{Luft}}\right)}^{*}{e}^{-\epsilon *L}+T_{\mathrm{Luft}}\epsilon =\frac{k_R}{m_M*c_{pm}}=\frac{k_R}{V_M*P_M*C_{pm}}$

[0151] The value T.sub.a of the water temperature and the value V.sub.z of the volume flow at the output port 12b are chosen such that, in the end region of each partial section of the circulation system, the water temperature is T.sub.ME<T.sub.soll and at the input port 12a the water temperature is T.sub.b<T.sub.soll with T.sub.soll−T.sub.b<θ, where θ>0 is a predetermined value.

[0152] It is understood that the circulation pump 10b is not always operated with a constant volume flow, i.e., regardless of whether the port inlet temperature 12a has exactly the setpoint value or even lies below it.

[0153] If the port inlet temperature 12a for various reasons should lie at 17° C. for example, where a max. of 20° C. is given, the delivery volume flow of the circulation pump 10b could be reduced. This can be done automatically, for example, under temperature control. As a result, energy savings will be achieved.

[0154] Likewise, in such a case the delivery volume flow of the pump 13 can be reduced by temperature control.

[0155] If the port inlet temperature for various reasons should lie at 17° C. for example (where a max. of 20° C. is given for example), the flow temperature in the refrigeration circuit could likewise be adjusted. As a result, energy savings would be achieved.

TABLE-US-00006 TABLE 1 Symbol Unit Designation Explanation c.sub.W kj(kg K) Specific heat capacity of the water Heat for the heating of 1 kg of water by 1 K (4.19 kj/(kg K)) ρ kg/m.sup.3 Density of the water Quotient of mass and volume of water at given temperature a.sub.a W(m.sup.2 K) Outward heat transmission Heat loss of a 1 m.sup.2 surface for a coefficient temperature difference between the surface and air of 1K λD W(m K) Thermal conductivity of the insulation λR W(m K) Thermal conductivity of the pipeline λges W(m K) Thermal conductivity of a insulation structural piece, here a pipeline incl. multilayered [00014]$\frac{1}{{\lambda }_{\mathrm{ges}}}$ (m K)W Thermal resistance [00015]$\frac{1}{U_R}$ (m K)W Heat transition resistance U.sub.R W(m K) Heat transfer coefficient for the Heat loss of a 1 m long insulated Pipe hot water pipe at a temperature difference between the water and the air of 1K d.sub.a mm Pipe outer diameter Outer diameter of a hot water line D mm Pipe outer diameter Outer diameter of an insulated hot water line L m Pipeline length Length of a partial section ϑ.sub.Luft ° C. Air/surrounding temperature Δϑa K Starting temperature difference Temperature difference between surroundings and medium at the start of a partial section ϑ.sub.MA ° C. Medium temperature at start Temperature of a medium at the start of a partial section ϑ.sub.ME ° C. Medium temperature at end Temperature of a medium at the end of a partial section

LIST OF REFERENCE NUMBERS

[0156] 1 Connection to a water supply network [0157] 2 Connection line [0158] 3 Consumer line [0159] 4 Collective feed line [0160] 5 Riser (down pipe) [0161] 6 Building floor line [0162] 7 Single supply line [0163] 8 Loop line [0164] 8a Static or dynamic flow division [0165] 9 Tapping point [0166] 10 Circulation system [0167] 10a Circulation conduit [0168] 10b Circulation pump [0169] 12 Cooling device [0170] 12a Input port [0171] 12b Output port [0172] 14 Heat exchanger [0173] 14a Input port [0174] 14b Output port