WO2009130294A2

WO2009130294A2 - A device for obtaining heat

Info

Publication number: WO2009130294A2
Application number: PCT/EP2009/054925
Authority: WO
Inventors: Klaus Engelhart; Thomas Prachar; Leo Obkircher; Stefan Jedrejcic; Christian Bichler
Original assignee: Vkr Holding A/S
Priority date: 2008-04-24
Filing date: 2009-04-24
Publication date: 2009-10-29
Also published as: EP2281152A2; WO2009130294A3; CA2722355A1; US20110083462A1

Abstract

The invention relates to a device (1) for obtaining heat, comprising a first brine circuit (2) in which at least a first brine pump (3) and at least one heat pump unit (40) with an outside register (5) for utilizing heat of the ambient air are arranged, and at least a second brine circuit (7) in which at least a second brine pump (9) and at least a solar collector (8) are arranged, with the second brine circuit (7) being thermally connected with a heat storage reservoir (11). In order to cover the largest possible number of operating states and to ensure high thermal efficiency, it is provided that the first and second brine circuit (2, 7) can be flow-connected with each other via a first valve (24), preferably a mixing valve.

Description

A device for obtaining heat

The invention relates to a device for obtaining heat, comprising at least a first brine circuit in which a first brine pump and at least one heat pump unit with an outside register for utilizing heat of the ambient air are arranged, and at least a second brine circuit in which at least a second brine pump and at least a solar collector are arranged, with the second brine circuit being thermally connected with a heat storage reservoir.

DE 28 09 425 Al describes a device for covering the heat requirement of the heat consumers of a building, comprising solar collectors which are flowed through by a heat transfer medium and a heat storage reservoir which can be brought into heat exchange with the heat transfer medium of the solar collectors, as well as a heat pump whose brine guided in a closed brine circuit can be brought into heat exchange with the heat storage reservoir. The brine circuit of the heat pump and the circuit of the solar collectors are arranged separated from one another in a hydraulic respect.

An environmental heat source for a heat pump is further known from EP 1 248 055 A2, in which at least two of the three environmental heat sources of air collector, terrestrial heat exchanger and solar absorber are connected in series and can each be bypassed by means of a changeover valve and a bypass line.

EP 0 931 986 Bl describes a solar-power-supplied heating and hot-water plant for a building, without an outside register for utilizing ambient air heat, comprising a solar collector and a solar distribution circuit having a flow pipe and return pipe. A combination heat storage reservoir and plant reservoir of downstream temperature levels are connected to a return distribution pipe in a serially activated manner. The plant reservoir with the lowest temperature level which is formed by a geothermal reservoir is optionally connected directly on the heat output side with a heat pump which supports the combination reservoir in a heat-injecting manner.

DE 199 27 027 Cl discloses an arrangement for obtaining heat from solar radiation and environmental energy, consisting of solar collector, heat pump, heat exchanger, temperature difference governors, fluid reservoirs, fluid lines, valves and pumps. The heat pump is connected on the evaporator side with a fluid reservoir with low temperature level and on the condenser side with a fluid reservoir with high temperature level, to which the heat consumers are connected. A further connection of the fluid reservoirs among each other is made thermally via heat exchangers. The solar collector can be optionally connected with a fluid reservoir each. A heat exchanger can be connected upstream of the solar collector with which the flow temperature of the collector can be raised to the level of the ambient temperature. The brine circuit of the solar collector and the water circuit of the water pump are arranged completely separate from each other.

EP 1 674 802 A2 discloses a multifunctional center for heating and/or cooling in residential buildings, comprising a cold store, a combination boiler, a heating circuit for heating the rooms, a device for generating hot water for domestic purposes, a water/water heat pump, an air/water heat pump, a solar brine circuit and a control device. The water/water heat pump is connected via lines both with the cold store as well as with the combination boiler. The air/water heat pump is connected with the cold store. The brine circuit is connected in a thermal respect both with the cold store as well as the combination boiler and is arranged to be completely separated from the circuits of the heat pumps.

Furthermore, a stratified storage reservoir is known from DE 299 14 113 Ul, comprising a housing and a water storage reservoir which is arranged therein and which comprises a water return in its bottom region and a water flow in its upper region. The water storage reservoir is subdivided by separating elements into at least two storage zones in which a latent storage material is held with different transformation temperatures.

Devices for obtaining heat with solar collectors tend to form condensation water especially at low outside temperatures, which substantially reduces the life of the solar collector. This problem can be solved with current plants only insufficiently, because it is only possible to use a relatively small number of operating modes.

It is the object of the invention to cover the largest possible number of operating states in a device for obtaining heat of the kind mentioned above. It is a further object of the invention to ensure a high thermal efficiency. It is further an object of the invention to enable effective defrosting in a device of the kind mentioned above.

This is achieved in accordance with the invention in such a way that the first and second brine circuit can be flow-connected with each other via a first valve, preferably a mixing valve, with the first valve preferably being arranged in the first brine circuit downstream of the outside register and upstream of the heat pump unit. The first and second brine circuit can be coupled when necessary via the mixing valve. As a result, the heat sources of solar and ambient air can be utilized both serially as well as independently of each other. The heat storage reservoir can be used as a third heat source. It is especially advantageous when the heat storage reservoir comprises several zones, preferably three stratified one above the other and partly separated, with the second brine circuit being thermally connected with the bottom zone.

In contrast to conventional heat pump systems, the possibility is offered to defrost by means of solar power. The bottom part of the heat storage reservoir is held at low temperature, e.g. heating room temperature, which gives the solar plant the possibility to supply energy to the system at the lowest possible temperature level. Since defrosting is made from the bottom zone of the heat storage reservoir, the degree of solar coverage is very high for this purpose.

It can be provided in a further development of the invention that a heating circuit can be connected with a middle zone of the heat storage reservoir. It is preferably further provided that a hot-water conditioning circuit is connected to the heat storage reservoir whose flow line starts from the upper zone of the heat storage reservoir and whose return line opens into the bottom zone of the heat storage reservoir. Heating circuit and hot-water circuit can be connected with each other via a second valve.

In order to enable direct heating with the heat pump, it is provided in a further embodiment of the invention that the heating circuit can be connected thermally via the heat pump with the first brine circuit. The outside register is operated for heating directly with the heat pump and the heat generated by the heat pump is supplied to the heating circuit. The return of the heating circuit can be guided via the heat storage reservoir, so that the heat stored therein can be utilized.

Rapid and efficient defrosting of the outside register of the heat pump unit can be achieved when the heating circuit can be connected via a connecting line with the bottom zone of the heat storage reservoir. It is provided that during the defrosting operation the first brine circuit is flow-connected with the second brine circuit, that the heating circuit is flow-connected via a connecting line with the bottom zone of the heat storage reservoir, and that thermal energy from the heating circuit is supplied to the first and second brine circuit via the heat exchanger.

In order to achieve rapid heat-up of the second brine circuit, it is especially advantageous when the connecting line opens via at least one nozzle into the bottom zone, with preferably the nozzle being directed against the heat exchanger. The connecting line advantageously originates from the feed line of the heating circuit. The flow through the connecting line can be adjusted via a second valve which is preferably arranged as a four-way valve. Furthermore, the heat pump can be used for reheating the fresh water circuit by actuating the second valve.

An especially rapid defrosting of the outside register is possible when a hot-water conditioning circuit is connected to the heat storage reservoir whose flow originates from an upper zone of the heat storage reservoir and whose return opens into the bottom zone of the heat storage reservoir, with preferably the heating circuit being connectable with the hot water conditioning circuit via the second valve which is arranged as a multiple-way valve.

It is especially advantageous when the temperature of the heating circuit can be adjusted via a third valve arranged as a mixing valve. The feed from the heat storage reservoir to the heating circuit can be controlled by means of the third valve. The feed can be adjusted and mixed continuously for example between two feed lines originating from different areas of the heat storage reservoir.

The invention is now explained in closer detail by reference to the drawings, wherein:

Fig. 1 shows the device in accordance with the invention in a schematic view;

Fig. 2 shows the device in a first operating state;

Fig. 3 shows the device in a second operating state;

Fig. 4 shows the device in a third operating state;

Fig. 5 shows the device in a fourth operating state;

Fig. 6 shows the device in a fifth operating state;

Fig. 7 shows the device in an alternative operating state;

Fig. 8 shows the device in a sixth operating state;

Fig. 9 shows the device in a seventh operating state;

Fig. 10 shows the device in an eighth operating state;

Fig. 11 shows the device in a ninth operating state, and

Fig. 12 shows a device for obtaining heat in accordance with the invention in an embodiment. As is shown in the drawings, device 1 for obtaining heat comprises in each embodiment a first brine circuit 2 with a first brine pump 3, as well as a heat pump unit 40 with a heat pump 4 and an outside register 5 which is subjected to ambient air via a fan 6. Furthermore, a second brine circuit 7 is provided with solar collectors 8 and a second brine pump 9, with said second brine circuit 7 being thermally connected with the bottom zone 10 of heat storage reservoir 11. The heat storage reservoir 11 comprises a total of three vertically stratified zones which are separated from each other by perforated plates for example, with a middle zone 12 being adjacent to a bottom zone 10 and an upper zone 13 being adjacent to the middle zone. The middle zone 12 of the heat storage reservoir 11 is connected with a heating circuit 14 for heating a building 15. Reference numeral 16 indicates a circulating pump of the heating circuit 14. The temperature in the heating circuit is set via a mixing valve 17 and a temperature sensor 18.

Device 1 further comprises a hot water conditioning circuit 19 with a circulating pump 20, with the hot water conditioning circuit 19 originating from the upper zone 13 of the heat storage reservoir 11 and opening into the bottom zone 10 of the heat storage reservoir 11. The hot water conditioning circuit 19 is thermally connected with a fresh water module 21 whose fresh water inlets and outlets are designated with reference numerals 22 and 23.

The pumps 3, 9 and 16 can be arranged with variable speed. The first and second brine circuit 2, 7 are filled with a brine, e.g. with glycol. The heating circuit 14 and the hot water conditioning circuit 19 on the other hand are filled with heating water.

In order to realize as many types of operation as possible, the first brine circuit 2 can be flow-connected with the second brine circuit 7 via a first valve 24 arranged as a mixing valve. The heating circuit 14 can be connected with the hot water conditioning circuit 19 via a second valve 25, e.g. a switching valve, and a connecting line 25a. Reference numerals 26 indicate further temperature sensors.

Since the first and second brine circuit 2, 7 can be combined via the first valve 24, the formation of condensation water in the solar collector 8 at low ambient temperatures can be prevented for example in such a way that the second brine circuit 7 is heated by the first brine circuit 2 with the heat pump unit 40 and the outside register 5. The large variability in the possibilities for switching and operating states is obtained especially in such a way that the heat sources of solar and ambient air can be utilized both in a serial manner as well as independent from each other. Moreover, there is the third possibility to use the heat storage reservoir 11 as a heat source.

In contrast to conventional heat pump systems, there is also the possibility to defrost the outside register 5 of the heat pump unit 4 by means of solar power, as will be explained in detail below (see operating state 7).

Various operating states of device 1 will be described below by way of example. Deactivated systems are indicated with the broken lines.

Operating state 1 : Heating or water heating by means of solar power (Fig. 2)

This operating state occurs when sufficient energy can be provided with the help of the solar collectors 8 in order to fulfill the need for heating or the need for hot water. The heat pump unit 40 is deactivated. The second brine circuit 7 is separated from the first brine circuit 2 by the first valve 24. Heat is supplied to the heat storage reservoir 11 via the second brine circuit 7, with the heat of the heat storage reservoir 11 being supplied to the heating circuit 14 and/or the heat water conditioning circuit 19. The energy is obtained on the one hand via the heating circuit 14 and on the other hand via the fresh water module 21. The connecting line 25a between the heating circuit 14 and the hot water conditioning circuit 19 is deactivated. The desired temperature in the heating circuit 14 can be set via the mixing valve 17 and the temperature sensor 18.

Operating state 2: Heating with the heat pump (Fig. 3)

This state occurs when on the one hand there is insufficient solar input and on the other hand the bottom zone 10 of the heat storage reservoir 11 is not at a sufficiently high temperature level. The outside register is operated in this operating state and the heat generated by the heat pump unit 40 is supplied directly to the heating circuit 14. The return of the heating circuit 14 is guided via the middle zone 12 of the heat storage reservoir 11, so that the heat stored therein can be utilized. The second brine circuit 7 with the solar collectors 8 is in operation, as is indicated by the broken lines. The hot water conditioning circuit 19 can be activated or deactivated, as required. The retrieval of fresh water via the fresh water module 21 is possible at any time. The connecting line 25a is deactivated via the valve 25. The first valve 24 interrupts the connection to the second brine circuit 7 and only releases the path to the outside register 5.

Operating state 3: Hot water loading by means of heat pump (Fig. 4)

As in the operating state 2, merely the outside register 5 is used for generating heat. The outside register 5 is in operation and withdraws heat from the ambient air. It is supplied via the heat pump unit 4 to the heating circuit 14. The connecting line 25a to the hot water conditioning circuit 19 is activated via valve 25, so that the medium of the heating circuit 14 is not guided to the line branch leading to the building 15, but via the connecting line 25a to the upper zone 13 of the heat storage reservoir 11. This leads to a direct heating of the upper zone 13 of the heat storage reservoir, through which hot water can be withdrawn very quickly from the fresh water module 21. As in the operating state 2, the connection between the first brine circuit 2 and the second brine circuit 7 is interrupted through the first valve 24.

Operating state 4: Reheating the fresh water area (Fig. 5)

This concerns a combined operation of first and second brine circuit 2, 7 and the heat storage reservoir 11. Energy is withdrawn from the ambient air primarily by means of the outside register 5. The first valve 24 is controlled in such a way that exactly so much energy reaches the second brine circuit 7 via the brine as can be taken "passively" from the heat storage reservoir 11 by means of the speed-controlled pump 9 of the second brine circuit 7, so that the solar collector 8 is not operated beneath the ambient temperature. As a result of this connection of the individual energy sources, condensation in the solar collector 8 is avoided. Furthermore, the upper zone 13 can be reloaded for hot water conditioning in operating state 4, in analogy to operating state 3.

Operating state 5: Combined reheating for the heating case (Fig. 6)

This operating state substantially corresponds to the operating state 4, with the difference that the heating circuit 14 is supplied with energy. The connecting line 25a is deactivated via the valve 25 and is switched to the heating path 14a leading to the building 15.

Fig. 7 shows an embodiment as an alternative to the operating states 4 and 5, in which the middle zone 12 of the heat storage reservoir 11 is supplied with energy. In this process, the heating circuit 14 is bridged via a bypass line 28 by means of valve 25, so that the heating medium is not supplied to the building 15, but directly to the heat storage reservoir 11.

Operating state 6: Direct solar reheating (Fig. 8)

Under the precondition that there is sufficient solar irradiation and the heat storage reservoir 11 is unable to supply energy directly to the heat pump unit 4, the second brine circuit 7 is operated without any admixing from the heat storage reservoir 11. It is relevant in this respect that the temperature in the line of the brine circuit 7 to the solar collector 8 does not exceed a threshold fixed in a controller (not shown). Heat is supplied to the heating circuit 14 via the heat pump unit 40.

Operating state 7: Defrosting (Fig. 9)

The state of defrosting occurs when too much ice forms on the outside register 5. Then it needs to be defrosted. This occurs in the present case by means of energy disposed in the heat storage reservoir 11. In this process, a compressor (not shown) as well as the fan 6 of the outside register 5 are switched off. The brine which is pumped to the outside register 5 is adjusted to approximately 15°.

Operating state 8: Avoidance of stagnation (Fig. 10)

In order to avoid stagnation, i.e. the evaporation of the brine in the second brine circuit, the present device 1 offers the possibility to discharge heat via the outside register 5 to the ambient environment. Protection from burning is important, so that the maximum temperature of the heat exchanger in the outside register 5 is set to 40° or 5° to 10° over the ambient temperature.

Operating state 9: Heating by means of energy from the heat storage reservoir 11 (Fig. 11)

The precondition is that sufficient energy is present in the heat storage reservoir 11, so that the heat pump unit 4 can be provided with energy for the heating circuit 14. This occurs for such a time until the heating room temperature plus a predetermined distance has been reached. Since the energy which is contained in the bottom zone 10 of the heat storage reservoir 11 is originated predominately by solar input, the efficiency of the overall system of device 1 can be increased substantially by this measure.

Operating state 10: Hot water conditioning by means of energy from the heat storage reservoir 11

This mode occurs in analogy to the operating state 9, with the difference that it is not the heating system that is thermally loaded, but the upper zone 13 of the heat storage reservoir 11. The connecting line 25a is activated by the valve 25.

Fig. 12 shows a device which is suitable for extended defrosting. Depending on the actual solar radiation it may occur that effective defrosting of the outside register 5 with solar power is not possible or advisable. Heat can be withdrawn from the heat storage reservoir 11 by means of the heat exchanger 27 of the second brine circuit 7 and be supplied to the first brine circuit 2 and thus the outside register 5. If the heat stored in the heat storage reservoir 11 is too low, then this measure is also not sufficient for effective defrosting of the outside register 5.

In order to still enable effective and rapid defrosting of the outside register 5, the heating circuit 14 is connected with the bottom zone 10 of the heat storage reservoir 11 via the second valve 25 and the connecting line 28, with the connecting line 28 opening into the heat storage reservoir 11 via a nozzle 29 facing the heat exchanger 27 of the second brine circuit 7. The thus occurring turbulent flow of the incoming heating medium heats the heat exchanger 27 formed by the heating coils and thus the brine of the second brine circuit 7 circulating therein, and subsequently the outside register 5 via the first brine circuit 2. Once the defrosting process of the outside register 5 has been completed, the flow through the connecting line 28 is closed by means of the second valve 25 and the first brine circuit 2 is uncoupled from the second brine circuit 7 by means of the first valve 24. Effective and rapid defrosting of the outside register 5 is thus possible even under adverse conditions.

Claims

CLAIMS:

1. A device (1) for obtaining heat, comprising a first brine circuit (2) in which at least a first brine pump (3) and at least one heat pump unit (40) with an outside register (5) for utilizing heat of the ambient air are arranged, and at least a second brine circuit (7) in which at least a second brine pump (9) and at least a solar collector (8) are arranged, with the second brine circuit (7) being thermally connected with a heat storage reservoir (11), characterized in that the first and second brine circuit (7, 7) can be flow- connected with each other via a first valve (24), preferably a mixing valve, with the first valve (24) preferably being arranged in the first brine circuit (2) downstream of the outside register (5) and upstream of the heat pump unit (40).

2. A device (1) according to claim 1, characterized in that the heat storage reservoir (11) comprises several zones (10, 11, 13), preferably three stratified one above the other and partly separated from each other, with the second brine circuit (7) being thermally connected with a bottom zone (10).

3. A device (1) according to claim 2, characterized in that a heating circuit (14) can be connected with a middle zone (12) of the heat storage reservoir (11).

4. A device (1) according to claim 3, characterized in that a hot-water conditioning circuit (19) is connected to the heat storage reservoir (11) whose flow line starts from an upper zone (13) of the heat storage reservoir (11) and whose return line opens into the bottom zone (10) of the heat storage reservoir (11).

5. A device (1) according to claim 3 and 4, characterized in that the heating circuit (14) can be connected with the hot water conditioning circuit (19) via a second valve (25) which is preferably arranged as a multiple-way valve.

6. A device (1) according to one of the claims 3 to 5, characterized in that the temperature of the heating circuit (14) can be adjusted via a third valve (17) arranged as a mixing valve.

7. A device (1) according to one of the claims 1 to 6, characterized in that a heating circuit (14) can be connected thermally via a heat pump (4) of the heat pump unit (40) with the first brine circuit (2).

8. A device (1) according to one of the claims 2 to 7, characterized in that a heating circuit (14) can be connected via a connecting line (28) with the bottom zone (10) of the heat storage reservoir (11).

9. A device (1) according to claim 8, characterized in that the connecting line (28) opens via at least one nozzle (29) into the bottom zone (10), with preferably the nozzle (29) facing the heat exchanger (27).

10. A device (1) according to claim 8 or 9, characterized in that the connecting line (28) branches off from the feed line (14a) of the heating circuit (14).

11. A device (1) according to one of the claims 8 to 10, characterized in that the flow through the connecting line (28) can be adjusted via a second valve (25) preferably arranged as a four-way valve.

12. A method for defrosting the device (1) for obtaining heat according to one of the claims 1 to 12, characterized in that during defrosting operation the first brine circuit (2) is flow-connected with the second brine circuit (7), that the heating circuit is flow-connected via a connecting line (28) with the bottom zone (10) of the heat storage reservoir (11), and that thermal energy from the heating circuit (14) is supplied to the first and second brine circuit (2, 7) via the heat exchanger (27).

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