DE10118572A1 - Heating and hot water supply, for a building, uses solar energy to heat them with an energy store to hold energy during low demand and a heat pump to give heating when the energy from the sun is low - Google Patents

Abstract

The heating system, to provide heat in a building and also hot water supplies, uses solar energy which is fed from the solar ray collector (5) to the heating system (1) and/or the hot water supply system (2) according to the availability of solar energy and the consumption of heat and hot water. The solar energy is fed into the systems directly on a high demand, and into an energy storage system (8) on a low demand. A heat pump (9) gives the energy supply when the available solar energy is low, and the demand is high.

Description

The invention relates to a heat supply system and to a Process of using solar energy to improve the efficiency of this System.

Methods of the type described above are used to heat Buildings and domestic water heating using efficient conversion renewable energy from solar radiation and with reduction or waiver the use of fossil fuels.

About a third of the primary energy used in Germany is in Households for air conditioning, v. a. Heating, the living rooms and Water heating used. This will primarily be fossil Energy sources used, their resources are limited and their costs continue to rise. In addition, the unbridled emission of carbon dioxide hides in the So far, the atmosphere has risks that have not been calculable.

The. Must make an important contribution to the necessary savings demonstrably high savings potential in the area of private households in Afford living area.

The heating energy requirement, however, is still a long way on average in the housing stock above the values specified as the target value. Not only with these values energetically-ecological, but also with economic efficiency achieve, it is necessary to consider the investment cost of the plant and its reduce their own energy requirements, but above all the use of offered to improve renewable energy.

If heat is generated at a low temperature, it can often hardly be used even if there are large amounts of heat. With the stake of heat pumps can use the electrical energy  Temperature raised, thus allowing the heat to be used become. With this procedure it is also possible to get heat from natural Sources such as B. wells or the ground and the To raise the temperature so that it can be used for space heating or Water heating is possible.

With heat pumps, there are certain operating conditions Evaporator icing. This is undesirable in an air evaporator. The icing of the air evaporator is currently discontinuous Heating of the endangered areas, i.e. additional energy use, counteracted. This makes the energy efficiency one Reduced heat pump system.

Various solutions are known in the prior art, in which Lower temperature heat sources for heat supply for heating and DHW heating can be used.

Devices are currently known, for example according to DE 198 27 511 A1, who use solar energy with high efficiency specifically for Enable low-energy houses and also a heat pump Use the compact unit via a control in the plant operation is involved and a heat exchanger and one in the air flow have downstream heat pump.

The heat is generated by a solar air collector. at high solar radiation and sufficient temperature, the solar heat is direct used for water heating.

If there is no solar radiation, heat can be extracted from a geothermal storage become. Then the temperature in the heat pump rises first, which compensates for the heat recovery losses.  

In other known solutions, for example according to DE 197 14 679 A1, are used instead of the geothermal storage buffer instead of the air collector, solar collectors, their heat transfer media Water, brine or other preferably frost-proof liquids. According to DE 29 71 6603 U1 a solution is known in which the Solar heat using a heat exchanger the source temperature of the Heat pump is increased.

Solutions are also known in which as a low-temperature reservoir either an earth collector or a solar-heated buffer storage is used. A Regulation decides which low-temperature reservoir from the Heat pump is used.

The solutions described have in common that each with high apparatus use only individual aspects of the integration of Heat sources of lower temperature realized in heat supply systems become.

The invention has for its object a method and an apparatus to further develop in accordance with the preambles of the independent claims, that solar energy regardless of its performance to improve the Efficiency of heat supply systems can be used. In particular should improve the efficiency of the heat supply system and the Supply and functional security can be increased.

The object of the invention is achieved in that, depending on the Solar radiation and the heat demand the solar energy different Is made available to consumers.  

A method according to the invention for heating and operating a water heating system with a storage system and a heat pump, which can be interconnected via a valve unit with a solar collector and the heat sinks (consumers), is that the solar collector with high solar radiation (approx. 400... 800 W / m ² ) directly serves to heat and operate a water heating system. If there is no decrease in the available heat by the consumer, it is fed to a storage system. At medium levels of radiation, the solar heat is used to raise the source temperature of the heat pump. If the heat pump has an air evaporator, then at low radiation levels (approx. 200 ... 400 W / m ² ) the evaporator is defrosted using a storage system charged with heat. This is preferably implemented using a latent memory.

By interconnecting the solar collector, storage system and heat pump with the consumers and the latent storage, the following advantages are connected:

• - The use of solar energy with high radiation intensity immediately for heating and hot water preparation and thus savings in Use of other energy sources.
• - The use of solar energy with low radiation intensity for Raising the source temperature and increasing the efficiency of the Heat pump of the heat supply system.
• - Increasing the efficiency of a solar collector and possibility of Energy generation with low radiation intensity.
• - The use of solar energy with low radiation intensity for Defrosting the air evaporator and thus increasing the efficiency of the Heat pump with air evaporator.

The invention is hereinafter described without limitation of the general The inventive concept based on exemplary embodiments with reference described on the drawings as an example. Show it.

Fig. 1 schematic representation of the device for performing the method according to the invention

Fig. 2 operating state of the system at a high solar radiation and high Space heat and / or hot water demand,

Fig. 3 operating state of the system with high solar radiation and a lack of heating and / or hot water demand

Fig. 4 operating state of the system with low solar radiation and high heating and / or hot water demand

Fig. 5 operating state of the system with iced air evaporator on the heat pump

Fig. 6 operating state of the system with low solar radiation and with high heating and / or hot water requirements

Fig. 7 operating state of the system without solar radiation and with high heating and / or hot water requirements

Fig. 8 air evaporator of the heat pump with latent storage defrost

In Fig. 1, an apparatus for performing the method according to the invention is shown schematically. The device is used for heating via heat exchangers 1 or 13 and / or for operating the water heating system via heat exchangers 2 or 14 . It consists of a solar collector 5 , which is connected via suitable shut-off devices, in particular the three-way valves 3 and 4 , directly to the heat exchangers 1 and 2 or to the evaporator 15 of the heat pump 9 and the storage system 8 . The pump 7 and the check valve 10 ensure the function of the device.

The incident solar energy heats the heat transfer fluid in the solar collector 5 . In the event of excessive heating, the heated heat transfer fluid flows directly through heat exchangers 1 (heating) and 1 or 2 (water heating system) and releases the heat. The flow of the heat transfer fluid is controlled by the three-way valves 3 , 4 and 6 . The three-way valves 3 and 4 control the supply of the heat transfer fluid to one or both heat exchangers 1 and 2 of the consumers, in accordance with the heat requirement.

In the case of low solar radiation, the little-heated heat transfer fluid is passed over the heat pump 9 , where its heat is extracted. The heat transfer fluid then cools down considerably. The solar collector 5 has a higher efficiency due to the higher temperature difference between the solar heat and the temperature of the heat transfer fluid. The heat extracted from the heat transfer fluid is available at the condenser with a higher, usable temperature and is supplied by the pump 11 , controlled by the three-way valve 12 , to the heat exchangers 13 (heating) and / or 14 (water heating system).

If the evaporator 15 of the heat pump 9 is designed as an air evaporator and there is a need to defrost it when icing, this can be done by means of solar radiation if the three-way valves 4 and 6 are in the appropriate position. The thermal energy required for this is provided by the solar collector 5 and / or taken from the storage system 8 .

If there is no solar radiation, the solar collector will not flow through. The pump 7 conveys heat transfer fluid which is heated in the storage system 8 . The heat is extracted from the heat pump 9 in the evaporator and used on the condenser for heating and for operating the water heating system.

The storage system 8 can be designed exclusively or in addition to other forms of storage as latent storage. The latent storage is then integrated into the evaporator 15 and thermally coupled to the latter via a heat exchanger. The properties of the latent material can be matched to the operating point of the heat pump in such a way that optimal operation with high efficiency is ensured.

By adjusting the latent properties, the latent memory is also able to efficiently defrost an air evaporator 15 on the heat pump 9 . According to the exemplary embodiment, this is the case when the latent temperature of the latent storage device is so far below the freezing point of the water that sufficient heat is released when the latent material changes state to defrost the air evaporator 15 .

According to a preferred embodiment, the latent material is paraffin.

In FIG. 2, the operation state of the system is shown at a high solar radiation, at the same time when a high demand for thermal energy for the heating and / or the heating of hot water, so the operation of the water heating system is. The pump 7 conveys the flow of the heat transfer fluid to the three-way valve 6 . This controls the current to the solar collector 5 , where the heat transfer fluid is heated by the solar radiation. The heat transfer fluid then flows through the three-way valve 4 and reaches the three-way valve 3 . The use of the heat is controlled at the three-way valve 3 , in which the flow of the heat transfer fluid is either passed to the heat exchanger 1 (heating) or 2 (water heating system) or to both at the same time. In practice, the heat gained in this operating state is mainly used to operate the water heating system, since high solar radiation is usually associated with low heat energy requirements for heating purposes.

This mode of operation is possible because the solar collectors usually Heat transfer fluid with high solar radiation with over 70 ° C emerges. In order to is a sufficiently high flow temperature for the applications mentioned reached. On the application of procedures further increase in temperature the heat transfer fluid can therefore be dispensed with and the The heat pump remains out of operation. However, you can always in if necessary Be put into operation.

If it is necessary to regulate the outlet temperature of the heat transfer fluid, a controllable pump 7 is to be used. It is also possible to operate the solar collector 5 optimally.

Fig. 3 shows the operating variant with high solar radiation and low, to be satisfied from a buffer, or missing heat demand and consumption. This frequently occurring operating case reduces the energetic and economic efficiency in solar thermal applications in practice, since the demand for large quantities of solar heat is low. This problem can be reduced by the possibility offered by the device in the operating case shown. An unlimited amount of heat is stored in the storage system 8 when it is designed as a geothermal storage.

The pump 7 conveys the heat transfer fluid, which is controlled by the three-way valves 6 and 4 , via the solar collector 5 . Thereafter, the heat transfer fluid flows through the evaporator 15 of the heat pump 9 without it being in operation. As a useful further development, the evaporator 15 of the heat pump 9 can therefore also be bypassed in the form of a bypass by means of a system (not shown) of valves and pipes in order to avoid unnecessary wear in the heat exchanger due to the abrasive effects of the flow of the heat transfer fluid.

If the storage system 8 is to be a geothermal storage, suitable geological conditions must be present, which are to be examined according to the prior art. The geothermal storage can be designed as a vertical hole. A probe is inserted into the ground, which transfers the heat from the heat transfer fluid to the ground or the heat transfer fluid water is pumped directly into the ground in a free circuit. In particular, there must be no groundwater flows as the necessary geological conditions and prerequisites, because this would also transport the heat to be stored away from the area of the storage and would result in it being lost. The geothermal storage can also be designed as a solid absorber or as a horizontal underground storage.

With the storage of solar heat in the ground can be disadvantageous Effects of heat removal by heat pumps z. B. on the Vegetation to be balanced.

Further variants of the storage system 8 are large-volume stores in which water is used as a heat carrier or storage liquid as an inexpensive material with a high thermal capacity. However, other heat carriers or storage liquids and solids with a sufficiently high specific heat capacity can also be used. The decision about the use of the design variants of the storage system 8 primarily depends on the size and capacity of the system. It is only from a certain peak heat requirement that the design of the storage system 8 as geothermal storage is economical. The reason for this is the high cost of geological exploration when looking for a suitable area for geothermal storage and for drilling the well.

In FIG. 4, the operating state of the system is shown in which low solar energy radiation is a high heat demand will be covered. The heat pump 9 is in operation, in the evaporator circuit of which the solar collector 5 and the storage system 8 are integrated and through which the heat transfer fluid flows. The condenser circuit of the heat pump 9 comprises the heat exchangers 13 and 14 , which are controlled via the three-way valve 12 as a function of the heat requirement for heating and / or the operation of the water heating system. Both circuits are driven by one pump each, with pump 7 in the evaporator circuit and pump 11 in the condenser circuit.

The evaporator circuit moves a sufficiently large amount of low temperature heat, which is obtained from the solar collector 5 and the storage system 8 designed as a geothermal heat store. This heat is extracted from the heat transfer fluid in the evaporator of the heat pump 9 again. The heat transfer fluid thus cooled has a high temperature difference to the heat sources in the storage system 8 and / or in the solar collector 5 and can thus absorb a larger amount of heat.

If both the storage system 8 and the solar collector 5 are to be flowed through, the outlet temperature of the heat transfer fluid from the storage system 8 must be significantly lower than that of the solar collector 5 so that use of the solar heat is ensured. If the exit temperature of the heat transfer fluid from the storage system 8 is equal to or higher than the exit temperature of the heat transfer fluid from the solar collector 5 , the operation according to FIG. 7 is switched over without solar radiation, since otherwise heat would be emitted from the storage system 8 via the solar collector 5 and thus for use would be lost. On the other hand, the operational management should be considered depending on the material used as the heat transfer fluid, since the heat transfer fluid runs the risk of freezing at very low outside temperatures. If brine or a glycol-water mixture is used as the heat transfer fluid, there is no danger.

If the solar collector 5 is of a correspondingly large size, mixed operation can also be avoided and the stored heat from the storage system 8 can be saved for operation without solar radiation. Due to the large-sized solar collector 5 , the required amount of heat plus the efficiency-related transmission losses are obtained at a low temperature and raised in the heat pump 9 to the temperature level with which it then leaves the heat pump 9 via the condenser circuit.

Useful developments of the condenser circuit with pump 11 , three-way valve 12 and the heat exchangers for heating 13 and water heating system 14 consist in the use of a buffer storage for the thermal energy of higher temperature. This buffer store could be arranged as a separate unit in a separate circuit or integrated into one of the heat exchangers 13 or 14 .

The illustration in Fig. 5 shows the device in the operating state of the system with a heat pump 9, the evaporator 15 is designed as an air evaporator or in combination of various methods can also be operated as an air evaporator. The heat obtained is transported in the condenser circuit by the heat transfer fluid and the pump 11 , controlled by the three-way valve 12 and supplied via the heat exchangers 13 and 14 for use in heating and / or in the water heating system.

When an air evaporator is in operation, the ambient air is passed over the heat exchanger of the evaporator 15 with the aid of a fan. Heat is extracted from the air by the temperature difference and made usable by the temperature increase in the heat pump 9 . If the evaporator 15 is cooled below the freezing point of the water, the evaporator 15 is easily iced up, since the atmospheric moisture condenses and freezes on the surface of the air evaporator. As the ice layer grows, there are restrictions in the efficiency of the heat pump 9 and even failure of the unit. For this reason, air evaporators according to the prior art are provided with defrosting devices which counteract this disadvantageous phenomenon. However, this requires the use of energy, usually electrical energy, which reduces the overall efficiency of a heat pump system with an air evaporator.

The device according to the invention uses solar energy to defrost an air evaporator used in the heat pump 9 . The solar heat is obtained in the solar collector 5 , through which the heat transfer fluid flows. The three-way valves 6 and 4 control the flow driven by the pump 7 .

If solar heat is available to a sufficient extent through solar radiation, the solar heat is conducted through the evaporator 15 and defrosts it. If the available solar heat is not sufficient, the three-way valve 6 switches off the line that guides the heat transfer fluid via the solar collector 5 . Then only the heat accumulator 8 is flowed through, which was previously fed and charged by excess solar heat which was not removed from the heat transfer fluid when the evaporator 15 was defrosted. It now gives off the heat with which the air evaporator is defrosted.

In addition to ensuring the function of the air evaporator, defrosting takes place at the same time an increase in the source temperature on the evaporator. So that increases the efficiency of the heat pump.  

In FIG. 6, the device for performing the method according to the invention shown in the operating condition with low solar radiation and high Space heat and / or hot water demand. The solar radiation alone is not sufficient to heat the heat transfer fluid so that there is a sufficient temperature difference in the heat exchangers 1 and 2 for heating and for operating the water heating system. Therefore, the heat transfer fluid heated by solar radiation is used to increase the source temperature of the heat pump 9 . The efficiency of the heat pump 9 is thus increased. It gives off the heat in the condenser circuit to the heat transfer fluid, which is conveyed by the pump 11 and the three-way valve 12 is controlled. The heat of the heating and the water heating system is supplied via the heat exchangers 13 and 14 , which can be flowed through selectively or at the same time.

In the evaporator circuit, the heat transfer fluid flows through the solar collector 5 , being conveyed by the pump 7 and being controlled by the three-way valves 6 and 4 . After the heat transfer fluid in the evaporator 15 of the heat pump 9 has been removed from the heat, it arrives at a very low temperature at the inlet of the solar collector 5 . As a result, there is a high temperature difference between the radiated solar heat and the temperature of the heat transfer fluid. This improves the heat transfer and increases the absolute heat capacity of the heat transfer fluid. This results in an increase in the efficiency of the solar collector 5 on the one hand, and on the other hand the possibility of using solar energy even with lower solar radiation and low outside temperatures.

A use of the device according to the invention in the operating case according to FIG. 6 would therefore still be possible even at low temperatures and minimal solar radiation, in contrast to conventional technology.

Fig. 7 shows the operating state of the device for performing the method according to the invention, in which the solar radiation is missing, but there is a high demand for heating and / or hot water. The heat pump 9 is in operation. Your capacitor circuit is interconnected with consumers as described in Fig. 4 and Fig. 6.

In this operating state, the evaporator circuit comprises, in addition to the evaporator of the heat pump 9, only the pump 7 , the three-way valve 6 and the storage system 8 . If the storage system 8 is to be a geothermal storage, suitable geological conditions must be present, which are to be examined according to the prior art. A probe is inserted into the soil, which transfers the heat from the heat transfer fluid into the soil, or the heat transfer fluid water is removed directly from the soil in a free circuit. The geothermal energy store can preferably be designed as a vertical bore or as a horizontal loop.

Further variants of the storage system 8 are large-volume stores, in which water is used as an inexpensive material as the heat carrier or storage liquid. However, other heat carriers or storage liquids, as well as solids with a sufficiently high specific heat capacity can also be used. The decision about the use of the design variants of the storage system 8 primarily depends on the size and capacity of the system.

The heat which is removed from the storage system by means of the heat transfer fluid serves as the heat source of the heat pump 9 , in whose evaporator 15 the heat is extracted.

Advantageously can be carried out, which has both an air evaporator 15, and a brine evaporator 15 in the heat pump cycle, a heat supply system as well. These are switched depending on the capacity. For example, the heat pump is supplied with heat at the beginning of the heating season via the brine evaporator 15 and the store 8 and at the end of the heating season when the store 8 has cooled down, the air evaporator 15 of the heat pump is operated. Especially since the air temperatures rise again due to the season.

Fig. 8 shows an air evaporator 15 of the heat pump 9 with latent storage defrost. For this purpose, the air evaporator 15 has a store 8 , which is designed as a latent store with paraffin. The surfaces of the air evaporator are kept free of ice and frost by the thermal coupling of the latent storage 8 with the refrigerant circuit 17 in the air evaporator 15 of the heat pump 9 . The latent memory is particularly advantageously loaded with solar energy.

LIST OF REFERENCES

1

Heat exchanger for heating in the solar collector evaporator circuit

2

Heat exchanger for water heating system in the solar collector / evaporator circuit

3

Shut-off device, three-way valve in the solar collector / evaporator circuit

4

Shut-off device, three-way valve in the solar collector / evaporator circuit

5

solar collector

6

Shut-off device, three-way valve in the solar collector ner steam generator circuit

7

Pump in the solar collector-nerdampfer circuit

8th

storage system

9

heat pump

10

check valve

11

Pump in the condenser circuit

12

Three-way valve in the condenser circuit

13

Heat exchanger for heating in the condenser circuit

14

Heat exchanger for water heating system in the condenser circuit

15

Evaporator / air evaporator of the heat pump

16

Heat transfer circuit

17

Refrigerant circuit of the heat pump

Claims (16)

1. Method for operating a heat supply system, characterized in that the solar energy is made available to various consumers depending on the solar radiation and the heat requirement. 2. The method according to claim 1, characterized in that the solar heat is fed into the heating ( 1 , 13 ) and / or the water heating system ( 2 , 14 ) with high solar energy radiation and high heating demand. 3. The method according to claim 1 or 2, characterized in that the solar heat is introduced into a storage system ( 8 ) when there is high solar energy radiation and low heating requirements. 4. The method according to any one of claims 1 to 3, characterized in that the solar heat is used to raise the source temperature for the operation of a heat pump ( 9 ) with low solar energy radiation and high heating demand. 5. The method according to any one of claims 1 to 3, characterized in that the solar heat is used to defrost an air evaporator ( 15 ) of a heat pump ( 9 ) at low solar energy radiation and high heating requirements. 6. The method according to claim 5, characterized in that for the defrosting of the air evaporator ( 15 ) of a heat pump ( 9 ), the solar heat is introduced into a latent heat store ( 8 ). 7. The device for performing a method according to claim 2, characterized in that the heat supply system has a circuit of heat transfer fluid, which further comprises at least one solar collector ( 5 ) and at least one heater ( 1 , 13 ) and / or at least one water heating system ( 2 , 14 ) includes. 8. The device according to claim 7 for performing a method according to claim 3, characterized in that the circuit of the heat transfer fluid additionally has the evaporator ( 15 ) of a heat pump ( 9 ) and a storage system ( 8 ). 9. The device according to claim 8, characterized in that the storage system ( 8 ) is designed as a geothermal storage. 10. The device according to one of claims 7 to 9 for performing a method according to claim 4, characterized in that the power and / or the speed of the pump ( 7 ) are adjustable. 11. The device according to one of claims 7 to 10 for performing a method according to claim 4, characterized in that in the circuit of the heat transfer fluid in the order of flow through the evaporator ( 15 ) of the heat pump ( 9 ), the storage system ( 8 ) and Solar collector ( 5 ) are integrated. 12. The device for performing a method according to claim 5, characterized in that an air evaporator ( 15 ) of a heat pump ( 9 ) and a solar collector ( 5 ) are arranged in the circuit of the heat transfer fluid and that the solar heat prevents icing of the air evaporator ( 15 ) , 13. The apparatus according to claim 12, characterized in that the air evaporator ( 15 ) has a latent heat accumulator ( 8 ) which is charged by the solar heat. 14. The apparatus according to claim 13, characterized in that the latent heat store ( 8 ) is a paraffin store. 15. The apparatus according to claim 14, characterized in that the Working point of the paraffin storage in such a way with that of the heat pump it is agreed that the optimum when operating the heat pump Working point is reached. 16. Device according to one of claims 7 to 15 for carrying out a method according to any one of claims 3 to 6, characterized in that the heat pump (9) of the heat supply system both an air evaporator (15) and a brine evaporator (15) to the heat pump ( 9 ).