Abstract
A method and a heat transfer system for limiting a supply flow (q.sub.S) in a heat transfer system which includes a supply conduit (10) with a supply flow (q.sub.S) and with a supply entry temperature (T.sub.S), and at least one load circuit (2) with a load pump (20) which provides a load flow (q.sub.L) with a load entry temperature (T.sub.L) and a load exit temperature (T.sub.R). The load entry temperature (T.sub.L) is set by way of changing the supply flow (q.sub.S), wherein the supply flow (q.sub.S) is limited to a maximal flow (q.sub.S, max), taking into account at least one temperature detected in the load circuit (2).
Claims
1. A method for limiting a supply flow in a heat transfer system, the method comprising the steps of: providing the heat transfer system such that the heat transfer system comprises: a supply conduit with a supply flow and a supply entry temperature; and at least one load circuit with a load pump which provides a load flow with a load entry temperature and a load exit temperature; setting the load entry temperature by changing the supply flow; and limiting the supply flow to a maximal flow while taking into account at least one temperature detected in the load circuit.
2. The method according to claim 1, wherein the provided heat transfer system further comprises at least one heat exchanger between the supply conduit and the load circuit.
3. The method according to claim 1, wherein the provided heat transfer system comprises at least one mixing device which mixes a load exit flow at least partly with the supply flow.
4. The method according to claim 1, wherein the supply flow is set on the basis of the load flow and of one or more temperature signals which are determined in the provided heat transfer system, on the basis of the supply entry temperature, the load entry temperature and the load exit temperature.
5. The method according to claim 1, wherein the supply flow is indirectly limited by way of at least one: limiting a thermal power flow in the load circuit; limiting the load exit temperature; limiting a difference between the load exit temperature and the load entry temperature.
6. The method according to claim 1, wherein for at least two input variables, in each case a maximal supply flow or a variable monotonic related to the maximal supply flow is determined on the basis of one of the input variables, and subsequently one of the determined maximal supply flows is selected for limiting the supply flow.
7. The method according to claim 1, wherein the supply flow is limited by limiting at least one of a speed of the load pump and a speed of a supply pump and by limiting an opening degree of a valve affecting the supply flow.
8. The method according to claim 1, wherein the supply flow is limited by limiting a control variable of a pressure controller or temperature controller affecting the supply flow.
9. The method according to claim 1, wherein the supply flow is limited by limiting a control variable of a control loop which regulates a load temperature and/or a load pressure in the load circuit including limiting a differential pressure across the load pump.
10. A heat transfer system comprising: a supply conduit for connection to a fluid supply; a return conduit for connection to a fluid return; at least one load circuit; a load pump operatively connected to the load circuit; a flow control device regulating a supply flow in the supply conduit, wherein the flow control device is configured to regulate a load entry temperature at an entry of the load circuit by way of regulating the supply flow; at least one temperature sensor operatively connected to the load circuit; and at least one limitation controller configured to directly or indirectly limit a supply flow to the load circuit to a predefined maximum in dependence on at least one temperature signal from the at least one temperature sensor.
11. The heat transfer system according to claim 10, further comprising at least one of a heat exchanger between the supply conduit and the load circuit and a mixing conduit which connects the exit of the load circuit to the supply conduit at a mixing point.
12. The heat transfer system according to claim 10, further comprising at least one of a pressure controller and a temperature controller operatively connected to the load circuit, wherein at least one of the pressure controller and the temperature controller is coupled to the limitation controller such that a control variable of the at least one of the pressure controller and the temperature controller can be limited by the limitation controller to a maximal value.
13. The heat transfer system according to claim 10, wherein the limitation controller is configured in a manner such that the limitation controller compares a thermal power flow in at least one of the load circuit and the load exit temperature and a difference between the load exit temperature and the load entry temperature, with an associated limit value and defines a maximum for a variable for setting the supply flow.
14. The heat transfer system according to claim 10, wherein the at least one temperature sensor is at least one of a temperature sensor arranged at the entry of the load circuit and detects a load entry temperature and a temperature sensor which is arranged at the exit of the load circuit and detects a load exit temperature.
15. The heat transfer system according to claim 10, wherein the flow control device comprises at least one of a supply pump which regulates the supply flow and a supply valve which regulates the supply flow.
16. The heat transfer system according to claim 10, wherein the load pump is configured for detecting a flow through the load circuit and is related to the flow control device for transmitting a signal corresponding to the detected flow.
17. The heat transfer system according to claim 10, wherein at least one of the flow control device and the limitation controller are integrated into a load pump assembly forming the load pump.
18. A heat transfer system supply flow method comprising the steps of: providing a heat transfer system comprising a supply conduit for connection to a fluid supply, a return conduit for connection to a fluid return, at least one load circuit, a load pump operatively connected to the load circuit, a flow control device for regulating a supply flow in the supply conduit, wherein the flow control device is configured to regulate a load entry temperature at an entry of the load circuit by way of regulating the supply flow, at least one temperature sensor operatively connected to the load circuit, at least one limitation controller configured to directly or indirectly limit a supply flow to the load circuit to a predefined maximum in dependence on at least one temperature signal from the at least one temperature sensor; setting the load entry temperature, with the flow control device, by changing the supply flow; and limiting the supply flow, with the at least one limitation controller, to a predefined maximum in dependence on at least one temperature signal from the at least one temperature sensor.
19. The method according to claim 18, wherein the provided heat transfer system further comprises at least one heat exchanger between the supply conduit and the load circuit.
20. The method according to claim 18, wherein the provided heat transfer system comprises at least one mixing device which mixes a load exit flow at least partly with the supply flow.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 is a heat transfer system, as is known from the state of the art;
(2) FIG. 2 is a control diagram showing an example of coupled controllers for limiting the supply flow by way of speed change of a pump;
(3) FIG. 3 is a control diagram showing an example of coupled controllers for limiting the heat flow and for limiting the speed of a pump;
(4) FIG. 4 is a view showing heat emission curves of a radiator;
(5) FIG. 5a is a pump curve for determining the flow at the pump;
(6) FIG. 5b is another pump curve for determining the flow at the pump;
(7) FIG. 6 is a control diagram showing an example of coupled controllers for limiting the return temperature by way of limiting a pump speed;
(8) FIG. 7 is a control diagram showing a coupled controllers for limiting the temperature difference in a mixing loop by way of limiting a pump speed;
(9) FIG. 8 is a control diagram showing a coupling of several different controllers for limiting the supply flow by way of limiting the speed of a pump;
(10) FIG. 9a is a schematic view showing an example for a heat transfer system with mixing loops according to the invention;
(11) FIG. 9b is a schematic view showing another example for a heat transfer system with mixing loops according to the invention;
(12) FIG. 9c is a schematic view showing another example for a heat transfer system with mixing loops according to the invention;
(13) FIG. 10 is a control diagram showing an example for coupled controllers for limiting the supply flow by way of limiting a control variable of a temperature controller;
(14) FIG. 11 is a control diagram showing an example of coupled controllers for limiting the heat flow by way of limiting a control variable of a temperature controller;
(15) FIG. 12 is a control diagram showing an example of coupled controllers for limiting the return temperature by way of limiting a control variable in a temperature controller;
(16) FIG. 13 is a control diagram showing coupled controllers for limiting the temperature difference in a mixing loop by way of limiting a control variable in a temperature controller;
(17) FIG. 14a is a schematic view showing an example of a heat transfer system in mixing loops according to the invention;
(18) FIG. 14b is a schematic view showing another example of a heat transfer system in mixing loops according to the invention; and
(19) FIG. 14c is another example of a heat transfer system in mixing loops according to the invention;
DESCRIPTION OF THE PREFERRED EMBODIMENTS
(20) Referring to the drawings, FIG. 1 shows a conventional heat transfer system with four heating circuits, for example heating circuits of a floor heating. The four heating circuits each have heat transfer means for locations to be temperature-controlled, in the form of load circuits 2. These are supplied by a heat source 4 via a supply 3 or a supply circuit, which comprises a feed 6 and a return 8. Supply conduits 10 lead from the feed 6 to the individual load circuits 2, and accordingly return conduits 12 lead back to the return 8 of the supply circuit. In this case, mixing devices are provided in the supply to the load circuits 2, for the closed-loop control of the feed temperature in the load circuits 2 at the entry, i.e. of the load entry temperature T.sub.L. These mixing devices consist of a mixing connection or a mixing conduit 14 which connects the exits 16 of the load circuits 2 to a mixing point 18 in the supply conduit 10. The load circuits in each case comprise a load pump 20 which produces a load flow through the load circuit 2, i.e. delivers the heat transfer medium through the load circuit 2. The load pump 20 is thereby an electromotorically driven circulation pump assembly. Thereby, the load pump 20 lies downstream of the mixing point 18, so that the flow through the load pump 20 comprises heat transfer medium or fluid from the mixing conduit 14 as well as from the supply conduit 10. In this manner, a mixing flow can be admixed through the mixing conduit 14 from the exit or return of the load circuit 2, to the supply flow in the supply conduit 10 which is likewise produced by the load pump 20, in order to reduce the feed temperature at the entry side, i.e. the load entry temperature T.sub.L with respect to the temperature in the feed 6 of the supply circuit.
(21) The setting of the mixing ratio is effected via a mixing valve 22 which is activated via a temperature controller 24. For this, the mixing valve 22 can be adjusted in its opening degree for example in an electromotoric manner. The temperature controller 24 detects a temperature signal corresponding to the load entry temperature T.sub.L, from a temperature sensor 25. In the example shown here, the mixing valve 22 is arranged in the supply conduit 10 upstream of the mixing point 18. The mixing valve however alternatively could also be arranged in the return conduit 12 downstream of the branching of the mixing conduit 14. If the load pump 20 delivers a predefined delivery flow, i.e. load flow, on closure of the mixing valve 22, then the supply flow in the supply conduit 10 is reduced and the difference to the load flow is sucked via the mixing conduit 14, so that a mixing flow in the mixing conduit 14 increases. If the load entry temperature T.sub.L is to be increased, the mixing valve 22 is opened via the temperature controller 24, so that the supply flow in the supply conduit 10 increases, and accordingly the share of the load flow which is made available via the mixing conduit 14 from the return reduces.
(22) It is to be understood that the same system would also function in a cooling system, with which a cold source is provided instead of a heat source 4. In such a system, the mixing device with a mixing conduit 14 would not serve for reducing the feed temperature, but conversely for increasing the feed temperature by way of admixing the heat transfer medium from the return.
(23) With the known arrangement, as is shown in FIG. 1, moreover balancing valves 26 are arranged in the return conduits 12 downstream of the branching of the mixing conduit 14. The balancing valves 26 serve for the hydraulic balancing between the several load circuits, by way of then limiting the maximal supply flow through the supply conduit 10 and the return conduit 12 for the individual load circuit. These valves are set manually. This, on the one hand, requires some effort and on the other hand there exits the problem that an optimal setting can only be achieved for one design point, and thus no optimal setting is given in other operating conditions, and the balancing valves 26 act as unnecessary throttles, which demands an increased power from the pumps in the system.
(24) According to the invention, this disadvantage is avoided, since the balancing valves 26 are done away with in the system according to the invention. The limitation of the supply flow q.sub.S in the supply conduit 10 for the hydraulic balancing between the several load circuits 2 in contrast is achieved by way of an electronic closed-loop control (regulation) of the valves and pumps which are present in any case and which set the supply flow, i.e. for example by way of a suitable control or regulation of the load pump 20 and/or of the mixing valve 22.
(25) According to the invention, for this, one envisages not having to directly detect the supply flow q.sub.S, but rather determining the supply flow q.sub.S whilst taking into account at least one temperature value detected in the load circuit 2, and then limiting it to a maximal value as the case may be.
(26) The computation or evaluation of the supply flow q.sub.S can be based on the following relationship between the supply flow q.sub.S, the load flow q.sub.L, load entry temperature T.sub.L at the entry side of the load circuit 2, the load exit temperature T.sub.R at the exit side 16 of the load circuit as well as the supply entry temperature T.sub.S in the supply conduit 10:
(27)
I.e. the supply flow can be computed from this relationship with the knowledge of the load flow q.sub.L in the load circuit 2, as well as the previously mentioned temperatures at the entry side and at the exit side of the load circuit 2 as well as in the supply flow q.sub.S in the supply conduit 10, so that it does not need to be determined directly. The load flow q.sub.L for example, as explained further below, can be determined directly in the load pump 20 from operating parameters of the load pump 20.
(28) FIG. 2 shows a first example of a combination of controllers for limiting the supply flow q.sub.S whilst taking into account the load flow q.sub.L, the load entry temperature T.sub.L, the load exit temperature T.sub.R as well as the supply entry temperature T.sub.S. Thus, a supply flow evaluation module 28 is provided, in which the supply flow q.sub.S is determined from the previously mentioned variables according to the equation specified above. The thus determined supply flow q.sub.S is fed as an input variable to a limitation controller 30, in which the thus determined supply flow q.sub.S is compared with a predefined maximal supply flow q.sub.S,max. In this example, the limitation controller 30 when reaching the predefined maximal delivery flow q.sub.S,max outputs a maximal speed n.sub.max which is led as a control variable to a pressure controller 32. The pressure controller 32 regulates the differential pressure across the load pump 20, i.e. between the entry and exit of the load pump 20. Thereby, it is the case of the differential pressure Dp.sub.L across the load circuit 2. This differential pressure is regulated to a differential pressure setpoint DP.sub.set by the pressure controller 32. The pressure controller 32 as an output variable outputs a speed n, with which the load pump 20 comprising a speed-controllable, electrical drive motor is operated. Thereby, the maximal speed n.sub.max which is set by the limitation controller is taken into account in a manner such that the speed n is limited to this maximal value. I.e. the load pump 20 is thus maximally operated with the maximal speed n.sub.max set by the limitation controller 30, so that the load flow q.sub.L and thus indirectly also the supply flow q.sub.S are limited when a temperature in the load circuit, for example the entry load temperature is controlled by adjusting the supply flow. This results from the thermal connection between the load flow and the supply flow. The supply flow results from the heat requirement of the load circuit.
(29) With the arrangement of several load circuits, each of the load circuits comprises a controller as was previously described by way of FIG. 2.
(30) FIG. 3 shows a further example of a coupling of several controllers, wherein here it is not directly the supply flow q.sub.S which forms the basis, but instead the heat flow dQ.sub.calc in a heat flow evaluation module 34. The load flow q.sub.L, the load entry temperature T.sub.L as well as the load exit temperature T.sub.R are also taken into account for determining the heat flow dQ.sub.calc. The absolute or complete heat flow dQ.sub.calc which is fed via the supply conduit 10 in the load circuit can thus be computed. This heat flow dQ.sub.calc in the limitation controller 30 is compared with a maximal heat flow dQ.sub.max which is predefined. The limitation controller 30, as is the case with the limitation controller 30, outputs a maximal speed n.sub.max for the load pump 20 and this maximal speed is then led to the pressure controller 32 as has been described above.
(31) Thus a limitation of the supply flow q.sub.S is also achieved with the variant shown in FIG. 3, since the supply flow q.sub.S is also indirectly limited by the limitation of the speed of the load pump 20. The considered heat flow dQ.sub.calc according to the following equation is dependent on the load flow q.sub.L as well as the load entry temperature T.sub.L as well as the load exit temperature T.sub.R:
Q.sub.calc=|q.sub.Lrhoc.sub.p(T.sub.LT.sub.R)|
In the above equation, c.sub.p is the specific heat capacity of the heat transfer medium, i.e. fluid, which flows through the system as a heat carrier. With rho, it is the case of density or mass density of this fluid. From the representation in FIG. 4, one can recognise that the load flow q.sub.L can be reduced or limited by way of limiting the heat flow dQ.sub.calc. The lines T.sub.R1, T.sub.R2 and T.sub.R3 in FIG. 4 display constant return temperature curves of a radiator or heat exchanger which e.g. can also be a floor heating circuit. If such a radiator is operated at a specific load entry temperature curve T.sub.L, the load flow q.sub.L can be reduced by a relatively large amount Dq.sub.L by way of reducing the heat flow dQ by the amount DdQ. Simultaneously, the return temperature or the load exit temperature reduces to the value T.sub.R2, so that the magnitude of the term T.sub.LT.sub.R in the above mentioned equation increases. This shows that thus the load flow q.sub.L is also necessarily reduced. This means that by way of limiting the heat flow dQ to a maximal value dQ.sub.max, it is possible to limit the load flow q.sub.L to a maximal value, in order thus to create a hydraulic balancing.
(32) As discussed above, the load flow can be determined directly in the load pump 20. This is effected by a computation or estimation on the basis of operating parameters of the load pump 20, specifically the current speed n and the pressure difference Dp across the load pump, or on the basis of the speed n and the taken-up electrical power P of the drive motor of the load pump 20.
(33) FIG. 5a shows a diagram, in which the differential pressure Dp is plotted against the flow q for different speeds n1 and n2. It is to be recognized that with a known speed and with a known differential pressure Dp, one can compute the load flow q.sub.L if the shown pump curves are known. Accordingly, FIG. 5b shows the electrical power P plotted against the flow q. In this diagram too, known curves for the speeds n1 and n2 are drawn in. Here too, one can recognise that with known curves of the pump, the load flow q.sub.L can be determined from the speed n and the electrical power P. Thus, one can make do without a special flow sensor for detecting the load flow q.sub.L.
(34) A third variant of the limitation of the supply flow q.sub.S in an indirect manner and which is in contrast to the controller arrangements shown in FIGS. 2 and 3 is possible by way of the controller arrangement shown by way of example in FIG. 6. Thus, the limitation controller 30 can limit the load exit temperature T.sub.R at the exit 16 of the load circuit 2 to a limit value T.sub.R0. The limitation controller 30 on reaching the limit value T.sub.R0 issues a maximal speed n.sub.max to the pressure controller 32 which is designed in exactly the same manner as has been described by way of FIGS. 2 and 3.
(35) Return temperatures, i.e. load exit temperatures T.sub.R at the exit 16 of the load circuit and which are too high and which would worsen the thermal efficiency of the system can be prevented in this manner.
(36) A further possibility of creating a hydraulic balancing between several load circuits can be achieved by the controller arrangement which is shown in FIG. 7. The temperature difference DT across the load circuit, i.e. the difference between the load entry temperature T.sub.L and the load exit temperature T.sub.R is held above or below a predefined limit value DT.sub.max with this controller. The load flow q.sub.L and, with this, as described above, also the supply flow q.sub.S will reduce with an increase of the absolute value of the temperature difference |DT|, so that an indirect limitation of the supply flow q.sub.S for the hydraulic balancing is possible via this. The values of the maximal temperature difference DT.sub.max as well as the detected temperature difference DT are taken into account as magnitudes without the sign (polarity), in the limitation controller 30 which is shown in FIG. 7, so that this controller can be applied with the same design for heating systems as well as for cooling systems. If the temperature difference reaches the mentioned limit value DT.sub.max, then the limitation controller 30 outputs a maximal speed n.sub.max to the pressure controller 32, as has been described above by way of the FIGS. 2, 3 and 6. Thus, here too, the speed of the pump and thus the load flow q.sub.L and simultaneously the supply flow q.sub.S are limited.
(37) FIG. 8 shows a combination of several of the previously described controllers.
(38) Thus at the top in FIG. 8, firstly the heat flow evaluation module 34 with the limitation controller 30 is shown. The limitation controller 30 of FIG. 6 is shown in the middle. The arrangement of the supply flow evaluation module 28 with the limitation controller 30 of FIG. 2 is shown at the bottom in FIG. 8. In this example, the limitation controller 30 outputs a maximal speed n.sub.max1, the limitation controller 30 a maximal speed n.sub.max2 and the limitation controller 30 a maximal speed n.sub.max3 for the load pump. These three maximal speeds n.sub.max1, n.sub.max2, and n.sub.max3 are led to a selection controller 36 or a selection device 36, in which one of these several maximal speeds is selected. In the shown example, this is the smallest of the three maximal speeds n.sub.max1, n.sub.max2, and n.sub.max3. As described by way of FIGS. 2, 6 and 3, this is then transferred to the pressure controller 32 as a control variable or maximal speed, so that the speed n issued by the pressure controller 32 is limited to the smallest value of the thus determined three maximal speeds n.sub.max1, n.sub.max2, and n.sub.max3. Instead of selecting the smallest of these speeds in the selection controller 36, this can also be configured so that the largest of these three speeds is selected.
(39) FIGS. 9a-9c show three examples for load circuits 2 with associated mixing loops of a heat transfer system, wherein it is to be understood that in each case several such arrangements of load circuits can be present in the heat transfer system. The arrangement in FIG. 9a corresponds essentially to the arrangement shown in FIG. 1. The supply 3 thereby comprises the feed 6 and the return 8 and here are represented only in a simplified manner. According to the invention, the balancing valve 26 in the return conduit 12 is done away with, in contrast to the embodiment example in FIG. 1. Apart from the load pump 20, here yet a flow sensor 38 which detects the load flow q.sub.L, is arranged in the feed to the load circuit 2. Alternatively, the load flow q.sub.L can however also be determined directly in the load pump 20 as described above. Here too, a temperature controller 24 is provided, which controls the load entry temperature T.sub.L by way of setting the mixing valve 22 in the manner described by way of FIG. 1. The arrangement furthermore comprises a balancing controller in the form of a control module (regulation module) 40 for limiting the supply flow q.sub.S in the manner described above. The control module 40, as is represented in FIG. 9a, as input variables receives the load flow q.sub.L, the load entry temperature T.sub.L, the supply entry temperature T.sub.S as well as the load exit temperature T.sub.R which here is not detected directly at the exit 16 but in the mixing conduit 14 by a temperature sensor. The temperature sensor 42 for detecting the load exit temperature T.sub.R could however also be arranged at the exit 16. The temperature at the exit 16 corresponds essentially to the temperature in the mixing conduit 14. The supply entry temperature T.sub.S is detected by a temperature sensor 44 in the supply conduit 10. The controller 40 comprises a controller arrangement, as has been described by way of the FIGS. 2, 3, 6, 7 and/or FIG. 8., and via the pressure controller 32 likewise contained in the control module 40 issues the speed, at which the load pump 20 is operated. Since the speed n is limited to a maximal value by the mentioned control modules in the described manner, thus the supply flow q.sub.S is also limited to a maximum via the control module 40 in the manner described above.
(40) FIG. 9b shows an alternative arrangement which differs from the design according to FIG. 9a in that the mixing valve 22 is arranged as a 3/2-way valve directly in the mixing point 18. The temperature controller 24 controls this mixing valve 22 for regulating the load entry temperature T.sub.L. The additional control module 40 corresponds to the control module described by way of FIG. 9a. It is merely the case that here the load flow q.sub.L is not determined via a separate sensor, but via the load pump 20 or its operating parameters, as described above. Here too, the control module 40 carries out a limitation of the supply flow q.sub.S by way of limiting the speed n of the load pump 20, as described above.
(41) A third variant of the load circuit 2 with a mixing loop of a heat transfer system according to the invention is shown in FIG. 9c. The embodiment shown there corresponds to the embodiment shown in FIG. 9b with the difference that the mixing valve 22 is done away with, and a supply pump 46 is arranged in the supply conduit 10 instead. The supply pump 46 is closed-loop controlled in its speed by the temperature controller 24, in order to control or regulate the load entry temperature T.sub.L to a predefined or desired value. I.e. the supply flow q.sub.S which is led to the mixing point 18, is closed-loop controlled via the supply pump 45. A mixing flow is additionally produced via the mixing conduit 14 by the load pump 20 if the load flow q.sub.L which is produced by the load pump 20, is larger than the supply flow q.sub.S. Additionally, the control module 40 in the manner described above effects a limitation of the supply flow q.sub.S, by way of it limiting the speed n of the load pump 20, as explained by way of FIGS. 2, 3, 6, 7 and/or 8. The load flow q.sub.L reduces if the speed n of the load pump 20 is limited or reduced in such a manner. If the supply pump 46 now firstly delivers an unchanged supply flow q.sub.S, then this leads to the fact that the admixing or mixing flow via the mixing conduit becomes smaller and thus the load entry temperature T.sub.L increases. This then initiates the temperature controller 24 to reduce the supply flow q.sub.S again, in order to lower the temperature. In this manner therefore, the supply flow q.sub.S is also indirectly reduced by the limitation of the speed n of the load pump 20.
(42) Instead of setting the control variable of a pressure controller 32 via a limitation controller 30 as described above by way of FIGS. 2, 3, 6, 7 and 8 the control variable of the temperature controller 24 could also be influenced in the same manner as explained by way of FIGS. 10-13.
(43) FIG. 10 shows the supply flow evaluation module 28, as has been explained by way of FIG. 2. A limitation controller 30 as has been described by way of FIG. 2 is moreover arranged at the exit side, and this limits the supply flow q.sub.S to a maximal supply flow q.sub.S,max. In contrast to the embodiment example according to FIG. 2, the limitation controller 30 here as a control variable does not output a maximal speed, but a maximal control variable u.sub.max which is transferred to the temperature controller 24. The temperature controller 24 serves for regulating the load entry temperature to a desired temperature T.sub.ref. For this, it outputs a control variable u which represents the valve opening degree of the valve 22, 22 or the speed of the supply pump q.sub.S. This means that the temperature controller 24 limits the control variable u to the maximal control variable u.sub.max which is set by the limitation controller 30, so that the supply flow q.sub.S is thus indirectly limited with a corresponding setting of the mixing valve 22, 22 or of the supply pump 46.
(44) FIG. 11 shows a controller arrangement which corresponds to the controller arrangement according to FIG. 3, only that here the pressure controller 32 is likewise replaced by the temperature controller 24. The limitation controller 30 described above by way of FIG. 3, as previously described by way of FIG. 10, does not output a maximal speed, but a maximal control variable u.sub.max, via which the control variable u is limited to this maximal value u.sub.max in the temperature controller 24 in the described manner.
(45) FIG. 12 shows a controller arrangement which corresponds to the controller arrangement which has been described by way of FIG. 6, with the difference that here too, the pressure controller 32 is replaced by the temperature controller 24, to which a maximal control variable u.sub.max is led as a limiting control variable. The temperature controller 24 thus limits the outputted control variable u to this value.
(46) FIG. 13 shows a controller arrangement which corresponds to the controller arrangement described by way FIG. 7, with the difference that here too, the pressure controller 32 is replaced by the temperature controller 24, to which a maximal control variable u.sub.max is led from the limitation controller 30, as has been described above by way of the FIGS. 10-12.
(47) With regard to the controller arrangements which are shown in the FIGS. 10, 11, 12 and 13 and have been described beforehand, it is to be understood that these too can be combined with one another in the manner as has been described by way of FIG. 8. A selection controller is then likewise provided, which selects the largest or smallest control variable from three maximal control variables u.sub.max1, u.sub.max2, and u.sub.max3 and transfers it to the temperature controller 24.
(48) FIGS. 14a-14c, in a manner similar to the FIGS. 9a-9c, show three embodiment examples of a part of a heat transfer system for realizing the closed-loop control principles which are described by way of FIGS. 10-13. Thereby, the design according to FIG. 14a basically corresponds to the arrangement according to FIG. 9a, the design according to FIG. 14b to the design according to FIG. 9b, and the design according to FIG. 14c to the design according to FIG. 9c. This, in particular, relates to the arrangement of the mixing valves 22 and 22 as well as of the supply pump 46 as well as of the temperature sensors and of the flow sensor 38. The description according to FIGS. 9a-9c is referred to with regard to this. Also, with regard to the arrangements which are shown in FIGS. 14a-14c, it is to be understood that preferably several such arrangements of load circuits 2 with associated mixing devices are arranged in a heat transfer system.
(49) In contrast to the designs according to FIGS. 9a-9c, the arrangements according to FIGS. 14a-14c are designed in order to carry out the control or limitation method as has been described by way of FIGS. 10-13. I.e. here no control module 40 is provided, but the limitation is carried out by the temperature controller 24 in the manner described by way of FIGS. 10-13. Thereby, the regulating principles according to FIGS. 10-13 can be realized individually or in combination, for example in the form of a combined controller according to the arrangement in FIG. 8.
(50) Otherwise, it is to be understood that the closed-loop control principle according to the invention could also be applied with heat transfer systems which use a heat exchanger instead of a mixing device. With such systems, a heat exchanger would be provided instead of the mixing conduit 14, wherein the supply flow q.sub.S flows through a first flow path of the heat exchanger via the supply conduit 10 and the return conduit 12, and the load flow q.sub.L through a second flow path through the load circuit 2. With such an arrangement, preferably a load pump 20 is provided in the load circuit, as well as a supply pump 46 in the supply circuit.
(51) Particularly preferably, the necessary closed-loop control components, in particular the control module 40 and/or the temperature controller 24 are integrated preferably into the pump assembly forming the load pump 20, in particular into a terminal box or electronics housing of this pump assembly.
(52) While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.
APPENDIX
List of Reference Characters
(53) 2load circuits 3supply 4heat source 6feed 8return 10supply conduits 12return conduits 14mixing conduit 16exit 18mixing point 20load pump 22, 22mixing valve 24temperature controller 26balancing valves 28supply flow evaluation module 30, 30, 30, 30limitation controller 32pressure controller 34heat flow evaluation module 36selection controller 38flow sensor 40control module 42, 44temperature sensors 46supply pump c.sub.Pspecific heat capacity of the heat transfer medium q.sub.Lload flow q.sub.Ssupply flow q.sub.S,maxmaximal supply flow nspeed n.sub.maxmaximal speed T.sub.Rload exit temperature T.sub.Ssupply temperature T.sub.Rload exit temperature, setpoint T.sub.Lload entry temperature Dqheat flow dQ.sub.calccomputed heat flow dQ.sub.maxmaxima heat flow rhodensity of the heat carrier T.sub.refdesired load entry temperature ucontrol variable u.sub.maxmaximal control variable Dp.sub.Ldifferential pressure across the load pump DP.sub.setsetpoint for the differential pressure across the load pump DTtemperature difference across the load circuit DT.sub.maxmaximal temperature difference
