EP1447626B1 - Multi-layered storage tank with return flow temperature control - Google Patents

Description

The invention relates to an arrangement according to the preamble of claim 1 and a method for storing hot water in a storage according to the preamble of claim 10. Such arrangements and methods are made EP-A-120 493 known.

Heated water storage previously offered on the market, especially stratified storage, are relatively expensive built, at least two sensors are arranged in the memory and two more in an associated heating circuit, in particular for regulating a hot water temperature (storage charging temperature), are usually supplied via the such stratified storage with energy. As an energy source for the heating circuit usually gas or oil burners and solar modules are used. For flow-calmed water supply and removal in the stratified storage or from this out structurally complex measures are proposed, nevertheless, turbulences or false flows can not be avoided in commercial equipment that destroy the stratification of the memory, especially under load.

Since the storage charging temperature at the hot water side hot water outlet of a plate heat exchanger must be the desired hot water temperature, known systems use a temperature sensor at the hot water outlet of the plate heat exchanger. With this, the storage charging temperature is detected and regulated. At least one other temperature sensor is necessary in the stratified storage to register a drop in storage temperature and to initiate a recharge. In the heating circuit with common heat generators at least one flow temperature sensor, but usually also a return temperature sensor available.

Currently, suitable stratified storage modules are known, especially for use in one- and two-family houses, which can be combined with condensing boilers. The problem with all these devices, however, is a temperature-accurate provision of hot water. This is partly due to the fact that there local stratified storage loading and unloading destroy the stratification of the already contained in the stratified storage hot water and thus a temperature-accurate stratification or maintaining the stratification is almost impossible. On the other hand, the temperature control to achieve an optimized storage charging temperature of the service water on local devices is very expensive, i. only possible with the help of complex temperature sensors.

The invention is therefore an object of the invention to provide a hot water tank and a temperature control for selbigen while avoiding the above disadvantages, which is simple and inexpensive and suitable to respond quickly to temperature changes in the stratified storage and provide a desired temperature of the service water.

This object is achieved by an arrangement according to claim 1 and by a method according to claim 10.

In this case, it has been recognized according to the invention that, taking into account predeterminable volume flows of the circulating water quantity in the domestic water circuit and in the heating circuit, the primary-side heating return temperature of the heat exchanger in about the hot water outlet temperature in the secondary circuit, ie the domestic water circuit corresponds. Due to this correlation of the return temperature and the hot water temperature, it is thus possible to use only one return temperature sensor in the heat generator according to the invention; Further temperature sensors, as required in the prior art, are therefore no longer necessary according to the invention. Due to the use of a stratified storage device according to the invention, in which, as described below, a disruption of the stratification within the memory is avoided that the inlet of the opening into the upper region of the stratified hot water pipe and / or the inlet of the leading away from the lower portion of the stratified storage Cold water outlet an upper or a lower Wasserleit- and -verteileinrichtung are assigned, thus corresponds to the hot water inlet temperature in the stratified storage of the hot water outlet temperature from the stratified storage. These two temperatures correlate with the return temperature and, according to a preferred embodiment, are identical or at least approximately identical to this.

According to the invention, it is provided that the heat exchanger in the DC or, especially in countercurrent, operable and is designed so that the heating circuit return temperature (T _RL ) corresponds approximately to the hot water temperature (T _WW ) in the hot water line between the heat exchanger and stratified storage.

It is preferred if the circulating volume flows in the heating circuit and process water circuit are designed so that an average temperature difference dT _WT of about -50 K across the heat exchanger is achieved.

It is furthermore preferred that the mean temperature difference dT _{WT can be varied} by a power grading on the circulating pump and / or the heating circuit pump. Thus, the full device performance can be used for storage recharge especially at low storage target temperatures.

Preferably, the circulating volume flow in the process water circuit is between about 200 l / h to 1000 l / h, in particular 400 l / h to 800 l / h and the circulating volume flow in Heizwasserkreislauf between about 400 l / h to 1400 l / h, in particular 600 l /H up to 1200 l / h. This relationship provides a good approximation of security that the heating circuit side return temperature of the heat exchanger corresponds approximately to the hot water temperature in the hot water circuit. Of course, in the heating circuit instead of water and another heat-emitting medium can be used with comparable heat capacity. When using a medium with lower heat capacity of the flow should be increased accordingly and vice versa.

Another advantage is given by the fact that when exceeding a predetermined switch-on temperature _difference dT _Eln between the measured storage _temperature T _SP and / or return _temperature T _RL and the predetermined _desired storage temperature T _Soll a charging process can be triggered, in which the circulation pump and / or the heater are switched on or ,

If, therefore, the measured storage temperature T _SP drops by, for example, 10 K below the _desired store temperature T _desired , a heat request is made by the temperature sensor in the stratified storage. The storage charging pump and the burner are subsequently switched on and the return temperature T _{RL of} the plate heat exchanger is regulated to the _desired storage temperature T _setpoint . Cold drinking water is sucked in from the bottom area of the stratified storage tank or at the same time tapping via the cold water inlet or heated in the plate heat exchanger to _desired storage temperature T _Soll and stratified over the hot water line between the heat exchanger and stratified storage. The stratified storage is thereby heated from top to bottom to _desired storage temperature T _Soll .

Preferably, the switch-on temperature difference dT _Ein , ie the difference between actual storage temperature minus storage target temperature in the range between -0.5 K and -15 K, preferably in the range between -1 K and -12 K and more preferably in the range between -2 K and -10 K. Due to the adjustable control hysteresis, with a maximum switch-on temperature difference dT _A -10 K, the running time or service life of the burner can be increased. With a small hysteresis of -2 K, a comfort gain is achieved by immediate recharging of the memory.

Another advantage of the invention is that when falling below a predetermined switch-off temperature difference dT _Aus between the measured storage temperature T _SP and / or return temperature T _RL and the predetermined storage _target temperature T _Soll the charging process is canceled, and the circulation pump and / or the heater off or be switched. When the top-rated hot domestic water or drinking water reaches a temperature sensor in the lower region of the stratified reservoir at a predetermined temperature, the storage charge is ended. The switch-off point is below the _desired store temperature T _setpoint in order to ensure a safe switch-off even with tolerances of the hot water temperature (store loading temperature). The circulation pump and / or the heater are switched off or switched from a current operating state.

The switch-off temperature difference dT _out , that is to say the difference between the actual temperature and the desired store temperature, preferably lies in the range between -0.5 K and -15 K, preferably in the range between -1 K and -12 K, and particularly preferably in the range between -2 K and -10 K, especially at -5 K.

It is preferred if the temperature sensor is arranged approximately at the level of the mouth of the cold water outlet in the lower region of the stratified storage. The positioning of the temperature sensor for measuring the storage temperature T _SP is particularly important for the performance of the hot water tank of great importance. A quick reaction in hot water tap is ensured by the positioning of the temperature sensor near the bottom of the stratified storage approximately at the level of the mouth of the cold water outlet. By inventively possible rapid reactions when reloading maximum performance characteristics of the hot water tank are achieved, so that at a storage water content of eg 90 liters, a power level is achieved, as it has a conventional memory with 160 to 200 liters content.

Preferably, the temperature sensor is placed between 1 cm and 12 cm, and more preferably between 2.5 cm and 4 cm above the bottom level of the stratified storage. This completes the temperature level falling from top to bottom detected and a fast memory charge drops below the switch-dT ensured _A.

According to the invention, the hot water tank, in particular stratified storage, in the upper part of the stratified storage a hot water pipe opening into the stratified storage and in the lower part of the stratified storage a cold water outlet, wherein the respective inlet and outlet are associated with an upper or a lower Wasserleit- and -verteileinrichtung ,

An essential point is that disturbances in the temperature profile of the water contained in the stratified storage can be reduced to a minimum by means of the water supply and distribution device in the bottom and lid region of the stratified storage. Advantageously, thus in the memory loading mode, i. when supplying hot water, ensures a temperature-accurate stratification of the hot water from top to bottom. In addition, it is ensured that even by the withdrawal of cold water no effect in the main volume of the stratified storage flow, which would interfere with the temperature stratification within the stratified storage is caused. In addition, it is ensured using the Wasserleit- and -verteileinrichtung invention that a heating from the cold state causes no significant temperature fluctuations during the tapping, so that withdrawn drinking or service water up to high dispensing volumes, for example, 15 l / min to 25 l / min is always substantially the same temperature.

It should be emphasized that the water supply and distribution device according to the invention, both in the bottom and in the lid region of the stratified storage unit, are provided individually or in combination with each other, depending on the desired and / or predetermined geometry of the stratified storage.

According to one embodiment, the upper Wasserleit- and -verteileinrichtung has an approximately horizontally extending, acting as a baffle plate distribution plate to which the hot water to be stored is directed so that forms a substantially horizontally extending flow upstream of the distribution plate. In a preferred manner is ensured so that einzubicherndes and flowing into the stratified storage hot water does not jet into the main volume of the stratified storage and leads to a mixing of the layers and a concomitant disturbance of the temperature stratification of the water already contained in the stratified storage.

By acting as a baffle plate distribution, the inflowing hot water is deflected above the level of the distribution plate so that it flows substantially horziontal and above the distribution plate forms a substantially annular flow, which spreads only gradually in the direction of cold water and the latter sieves quasi downwards, but without causing mixing with the cold water.

It is advantageous if the guidance and distribution system according to the invention provides a relatively large dimensioning of the distribution plate in order to ensure optimized flow guidance.

According to one embodiment of the invention, an end of the distribution plate facing a wall of the layer reservoir is angled in the direction of an inflow side in such a way that a flow acting in the direction of the inflow side is formed there.

In this way it is ensured that at the distribution plate a uniform homogeneous flow in a substantially horizontal plane is formed with a small proportion upwards. Thus, incoming flows are deflected by the inventive Wasserleit- and -Verteileinrichtung in an advantageous manner so that they are limited to the uppermost volume range of the stratified storage in the stratified storage. Temperature fluctuations, even at the beginning of the charging process, are thus compensated, since mixing of the stratified storage contents is ruled out from the outset.

According to the invention, a hot water tap takes place in the cover area of the stratified storage tank. Characterized in that inflowing hot water is fluidically deflected so that it is initially present only in the uppermost volume range of the stratified storage, a hot water tap is also in a completely discharged memory practically immediately possible, since a cooling of the inflowing hot water with a stratified underneath cold water does not take place.

In preferred embodiments of the method according to the invention, different operating steps are provided, depending on the process water removal and the height thereof.

Thus, in the case of no service water removal, first a predetermined switch-on temperature difference dT _A between a predetermined _desired storage temperature T _desired and a measured storage temperature T _{SP is} monitored. When this switch-on temperature difference dT _{Ein is} exceeded, switching on or switching over the circulation pump and / or the heater for withdrawing a volume flow of cold water from the cold water outlet, the heating of the same in the heat exchanger and storing the volume flow as hot water through the hot water line in the stratified storage. Finally, when a predetermined switch-off temperature difference dT _Aus between the storage tank temperature T _SP and a return temperature T _RL in the heating circuit-side return line is reached, the circulation pump and / or the heater is switched off or switched over.

A hot water outlet made which is less than the maximum recoverable flow einzuspeichernden hot water _A is followed by the step of monitoring a predetermined switch-dT switching on or switching over the circulating pump and / or the heater on when the switch-dT is exceeded _A. In this case, a volume flow of cold water is withdrawn from the cold water inlet, heated in the heat exchanger and stored again as hot water via the hot water pipe into the stratified storage. Finally, the switching-off or switching over of the circulation pump and / or of the heater takes place when a predetermined switch-off temperature difference dT _Aus between the desired store temperature T _SP and the actual temperature is reached.

In a further operating state is in the case of a hot water, which is greater than the maximum recoverable volume flow to be stored hot water as a result of monitoring a predetermined switch-on temperature difference dT _A the switching on or switching over the circulating pump and / or of the heating device made when the switch-dT is exceeded _A. In this case, a partial volume flow of cold water is withdrawn from the cold water inlet, heated in the heat exchanger and stored as hot water through the hot water line in the stratified storage, and fed another partial volume flow of cold water from the cold water inlet via the cold water outlet into the stratified storage. The circulation pump and / or the heater are switched off or switched when a predetermined switch-off temperature difference dT _out between the desired storage temperature T _SP and the actual storage temperature is reached.

Further embodiments of the invention will become apparent from the dependent claims.

Fig. 1

eine Ausführungsform der Erfindung, bei der ein Brauchwasserkreislauf und ein Heizkreislauf über einen im Gleichstrom betriebenen Plattenwärmetauscher miteinander gekoppelt sind.

The invention will be described with reference to an embodiment which is explained in more detail with reference to the figure. Hereby shows:

Fig. 1

an embodiment of the invention in which a hot water circuit and a heating circuit are coupled together via a co-current operated plate heat exchanger.

In the following description, the same reference numerals are used for the same and like parts.

The single FIGURE shows a service water circuit B and a heating circuit H, which are coupled together via a DC operated plate heat exchanger 9. The process water circuit B comprises a cold water inlet 12, which is connected to a cold water outlet 4 of a stratified storage 6. In the cold water outlet 4, a circulating pump 7 is arranged, which transports cold water to the plate heat exchanger 9, where it is heated and supplied as hot water via a hot water pipe 5 to an upper portion of the stratified storage 6. About a service water extraction line 13, the mouth 2 is also located in the upper part of the layer memory 6, the heated water can be removed. Furthermore, a temperature sensor 1 for measuring a storage temperature T _SP at the level of the mouth 3 of the cold water outlet 4 is arranged.

The heating circuit H comprises a burner heating water heat exchanger 10, which may be gas-operated, for example. From this Heizwasserwärmetauscher 10 extends a flow line 11 for heating circuit side water inlet of the plate heat exchanger 9 and a return line 14 with an associated return temperature sensor 15 and a heating circuit 8 from the heating circuit side water outlet back to Heizwasswärmetauscher 10. The plate heat exchanger 9 is designed so that the hot water temperature T _WW in the hot water pipe 5 between plate heat exchanger 9 and layer memory 6 of the return temperature T _RL corresponds. Here, the target temperature T _{target of} the stratified storage 6 serves as a reference variable for the return temperature T _RL . This is a - usually necessary - further temperature sensor in the range of the user water side water outlet to the hot water pipe 5 or in the same superfluous. The usually already provided in the heating circuit temperature sensor for the return temperature T _RL is thus sufficient to couple a layer memory as shown stratified storage 6 to existing heating circuits. Furthermore, only the temperature sensor 1 for measuring the actual storage temperature T _{SP is} necessary for the regulation in order to be able to assess the temperature profile in the layer structure and to use it for regulation. Depending on the amount of service water removal via the service water extraction line 13, the circulating volume flows in the process water circuit and in the heating circuit by means of the circulation pump 7 and the heating circuit 8 can be adjusted so that the return temperature T _RL always corresponds approximately to the hot water temperature (storage _charging temperature) T _WW . The positioning of the temperature sensor 1 at the level of the mouth 3 of the cold water outlet 4 ensures a rapid response when reloading the stratified storage 6, whereby maximum performance characteristics are achieved. For example, if a switch-dT _A set between a predetermined storage target temperature T _target and a measured at the temperature sensor 1 storage temperature T _SP of -5 K, so when crossing this switch-dT _A is switched on or switched the circulation pump 7 and / or the heating water heat 10th The heating circuit-side return temperature T _RL is then regulated to _desired storage temperature T _setpoint . Cold drinking water is heated in the plate heat exchanger 9 and layered on the hot water pipe 5 in the stratified storage 6. This finally happens until a predetermined switch-off temperature difference dT _off between the storage actual _temperature T _RL and the storage _target temperature T _setpoint of, for example, -2 K is reached. In this case, the circulation pump 7 and / or the Heizwasserwärmetauscher 10 are switched off or switched.

LIST OF REFERENCE NUMBERS

B

Hot water circuit

H

heating circuit

T _RL

Return temperature or storage temperature

T _SP

storage temperature

T _VL

flow temperature

T _WW

Hot water temperature

T _target

Stratified storage target temperature

dT _WT

Water temperature difference

T _A

Switch-on

T _off

Switch-off

1

temperature sensor

2

Brauchwasserauslass

3

Mouth of the cold water outlet

4

Cold water withdrawal

5

Hot water pipe

6

stratified storage

7

circulating pump

8th

Heating circuit

9

Plate heat exchanger

10

Heating water heat exchanger

11

supply line

12

Cold water supply

13

Water extraction line

14

Return line

15

Return temperature sensor

Claims (18)

1. Arrangement consisting of a hot water storage tank, especially a stratified storage tank (6), a consumer water circuit (B) and a heating circuit (H), having a cold water feed (12), a consumer water draw-off line (13) and a cold water outlet (4) leading out of the lower region of the hot water storage tank (6), in the course of which outlet a circulating pump (7) is arranged and which leads to a heat exchanger (9) from which a hot water line (5) opens into the upper region of the hot water storage tank (6), the heat exchanger (9) being associated with the heating circuit (H) which has a heating apparatus (10), a heating circuit pump (8) and a supply line (11) and return line (12),
   characterized in that
   the heat exchanger (9) is in the form of a plate heat exchanger operable in parallel-flow mode or, especially, counter-flow mode and is so arranged that the heating-circuit-side return temperature (T_RL) of the plate heat exchanger (9) corresponds approximately to the hot water temperature (T_WW) in the consumer water circuit (B), that is to say in the hot water line (5) between the plate heat exchanger (9) and the hot water storage tank (6).
2. Arrangement according to claim 1 or 2,
   characterized in that
   a mean temperature difference (dT_WT) is variable by stepped control of the output at the circulating, pump (7) and/or the heating circuit pump (8).
3. Arrangement according to either one of the preceding claims,
   characterized in that
   when the difference between the measured storage tank temperature (T_SP) and the predetermined desired storage tank temperature (T_soll) exceeds a preset switch-on temperature difference (dT_Ein), a charging operation is initiatable in which the circulating pump (7) and/or the heating apparatus (10) are switched on or switched over.
4. Arrangement according to claim 3,
   characterized in that
   the switch-on temperature difference (dT_Ein) is in the range between -0.5 K and -15 K, preferably in the range between -1 K and -12 K and especially in the range between -2 K and -10 K.
5. Arrangement according to any one of the preceding claims,
   characterized in that
   when the difference between the measured storage tank temperature (T_SP) and the predetermined desired storage tank temperature (T_Soll) falls below a preset switch-off temperature difference (dT_Aus), the charging operation is discontinuable, and the circulating pump (7) and/or the heating apparatus (10) are switched off or switched over.
6. Arrangement according to claim 5,
   characterized in that
   the switch-off temperature difference (dT_Aus) is in the range between -0.5 K and -15 K, preferably in the range between -1 K and -12 K and especially in the range between -2 K and -10 K, more especially -5 K.
7. Arrangement according to any one of the preceding claims,
   characterized in that
   for temperature regulation, only one temperature sensor (1) in the stratified storage tank (6) and one return temperature sensor (15) in the region of the return line (14) of the heating circuit (H) is provided, especially required.
8. Arrangement according to claim 7,
   characterized in that
   the temperature sensor (1) is arranged at approximately the height of the opening (3) of the cold water outlet (4) in the lower region of the stratified storage tank (6).
9. Arrangement according to claim 7 or 8,
   characterized in that
   the temperature sensor (1) is arranged between 2.0cm and 10 cm above the base level of the stratified storage tank (6).
10. Method of storing hot water in a hot water storage tank of an arrangement consisting of a heating circuit (H) and the hot water storage tank, especially a stratified storage tank (6), which is provided in a consumer water circuit (B), a cold water feed (12), a consumer water draw-off line (13) and a cold water outlet (4) leading out of the lower region of the hot water storage tank (6), in the course of which outlet a circulating pump (7) is arranged and which leads to a heat exchanger (9) from which a hot water line (5) opens into the upper region of the hot water storage tank (6), the heat exchanger (9) being associated with the heating circuit (H) which has a heating apparatus (10), a heating circuit pump (8) and a supply line (11) and a return line (14),
    characterized in that
    the heat exchanger (9), which is in the form of a plate heat exchanger, in parallel-flow mode or, especially, counter-flow mode, and the arrangement is operated so that the heating-circuit-side return temperature (T_RL) of the plate heat exchanger (9) corresponds approximately to the hot water temperature (T_WW) in the consumer water circuit (B), that is to say in the hot water line (5) between the plate heat exchanger (9) and the hot water storage tank (6).
11. Method according to claim 10,
    characterized in that
    a mean temperature difference (dT_WT) is variable by stepped control of the output at the circulating pump (7) and/or the heating circuit pump (8).
12. Method according to either one of the preceding claims 10 and 11,
    characterized in that
    when the difference between the measured storage tank temperature (T_SP) and the predetermined desired storage tank temperature (T_soll) exceeds a preset switch-on temperature difference (dT_Ein), a charging operation is initiated in which the circulating pump (7) and/or the heating apparatus (10) are switched on or switched over.
13. Method according to claim 12,
    characterized in that
    the switch-on temperature difference (dT_Ein) is selected in the range between -0.5 K and -15 K, preferably in the range between -1 K and -12 K and especially in the range between -2 K and -10 K.
14. Method according to any one of the preceding claims 10 to 13,
    characterized in that
    when the difference between the measured storage tank temperature (T_SP) and the predetermined desired storage tank temperature (T_Soll) falls below a preset switch-off temperature difference (dT_Aus), the charging operation is discontinued, and the circulating pump (7) and/or the heating apparatus (10) are switched off or switched over.
15. Method according to claim 14,
    characterized in that
    the switch-off temperature difference (dT_Aus) is selected in the range between -0.5 K and -15 K, preferably in the range between -1 K and -12 K and especially in the range between -2 K and -10 K, more especially -5 K.
16. Method according to any one of the preceding claims 10 to 15,
    characterized by
    the following steps when no consumer water is drawn off:

    - monitoring a preset switch-on temperature difference (dT_Ein) between a predetermined desired storage tank temperature (T_Soll) and a measured storage tank temperature (T_SP);

    - switching on or switching over the circulating pump (7) and/or the heating apparatus (10) for withdrawal of a volume flow of cold water from the cold water outlet (4), heating that volume flow in the heat exchanger (9) and feeding the volume flow in the form of hot water into the stratified storage tank (6) by way of the hot water line (5) when the switch-on temperature difference (dT_Ein) is exceeded; and

    - switching off or switching over the circulating pump (7) and/or the heating apparatus (10) when a preset switch-off temperature difference (dT_Aus) between the storage tank temperature (T_SP) and the desired storage tank temperature has been reached.
17. Method according to any one of the preceding claims 10 to 15,
    characterized by
    the following steps when the amount of consumer water drawn off is less than the maximum deliverable volume flow of hot water to be fed into the storage tank:

    - monitoring a preset switch-on temperature difference (dT_Ein) between a predetermined desired storage tank temperature (T_Soll) and a measured storage tank temperature (T_SP);

    - switching on or switching over the circulating pump (7) and/or the heating apparatus (10) for withdrawal of a volume flow of cold water from the cold water feed (12), heating that volume flow in the heat exchanger (9) and feeding the volume flow in the form of hot water into the stratified storage tank (6) by way of the hot water line (5) when the switch-on temperature difference (dT_Ein) is exceeded; and

    - switching off or switching over the circulating pump (7) and/or the heating apparatus (10) when a preset switch-off temperature difference (dT_Aus) between the storage tank temperature (T_SP) and the desired storage tank temperature has been reached.
18. Method according to any one of the preceding claims 10 to 15,
    characterized by
    the following steps when the amount of consumer water drawn off is greater than the maximum deliverable volume flow of hot water to be fed into the storage tank:

    - monitoring a preset switch-on temperature difference (dT_Ein) between a predetermined desired storage tank temperature (T_Soll) and a measured storage tank temperature (T_SP);

    - switching on or switching over the circulating pump (7) and/or the heating apparatus (10) for withdrawal of a partial volume flow of cold water from the cold water feed (12), heating that volume flow in the heat exchanger (9) and feeding the volume flow in the form of hot water into the stratified storage tank (6) by way of the hot water line (5), and supplying a different partial volume flow of cold water from the cold water feed (12) to the stratified storage tank (6) by way of the cold water outlet when the switch-on temperature difference (dT_Ein) is exceeded; and

    - switching off or switching over the circulating pump (7) and/or the heating apparatus (10) when a preset switch-off temperature difference (dT_Aus) between the storage tank temperature (T_SP) and the desired storage tank temperature has been reached.

Images