AT516403B1 - Process for the regeneration of the primary energy storage of a brine water heat pump - Google Patents

Abstract

The invention relates to a method for regenerating the primary energy store (1) of a brine heat pump (4), in which a preferably designed as a metallic fin heat exchanger Luftsolewärmetauscher (3) is connected in series in the primary circuit of the brine heat pump (4), in such a way that the Solepumpe (6) is operated even if the cooling circuit of the heat pump (4) is deactivated. Thus, the space requirement for the primary energy storage (1) can be reduced to a fraction of a conventional surface collector. The air-oil heat exchanger (3) is preferably operated with exclusively natural air movement.

Description

description

METHOD FOR REGENERATING THE PRIMARY ENERGY STORAGE OF A SOLE WATER HEAT PUMP

BACKGROUND AND FIELD OF THE INVENTION

The invention relates to a method for the regeneration of the primary energy storage of a brine heat pump according to the independent claims.

PREVIOUS STATE OF THE ART

From EP 2 246 633 A2 a method for the use of solar heat is known, in which the solar energy output can be passed in addition to a heating circuit and a hot water tank on a geothermal probe. In contrast to the method according to the invention, however, the soil surrounding the probe is regenerated exclusively by solar energy and not by the heat energy of ambient air.

From EP 2 151 637 A2 an arrangement for the provision of domestic hot water is known, in which a solar circuit with a solar collector and a consumer on the one hand, and the primary circuit of a heat pump (brine circuit) are thermally coupled via a heat exchanger on the other hand. The extent of thermal coupling is determined by a mixing valve. The arrangement allows the use of solar energy in particular when the sunlight is no longer sufficient to reach the temperature level of the consumer in the solar circuit, but the temperature level is above that of the primary circuit of the heat pump.

From EP 1 248 055 A2 a total environmental heat source is known in which in the primary circuit of a heat pump up to the three heat sources (geothermal heat exchanger, air collector, solar absorber) are connected in series, the heat sources each individually by a controlled by a switching valve bypass Line can be bypassed. Thus, under the given conditions, the best heat source (or combination of heat sources) for the operation of the heat pump can be selected. In contrast to the process according to the invention, however, EP 1 248 055 A2 does not provide any circulation of the heat transfer medium - and therefore also no energy exchange between the heat sources - when the heat pump is not in operation. Furthermore, in EP 1 248 055 A2, a change-over valve is provided for each individual heat source, while in the method according to the invention only a single switching element is necessary because the ground collector is always located in the primary circuit of the heat pump.

In WO 2012/032159 A2 a storage tank is proposed, which uses the latent heat energy of a storage medium, in particular water. In the center of the storage tank is a first heat exchanger through which the storage tank is preferably deprived of energy by a heat pump. Two further heat exchangers, which are cast for example in the housing wall of the storage tank and surround the first heat exchanger, serve for regeneration. The heat transfer medium of the second heat exchanger is preferably a gas, in particular ambient air or sewage air, that of the third is a liquid, via which the storage tank preferably obtained from solar absorbers energy is supplied. In contrast to the method according to the invention, different heat exchangers are proposed in WO 2012/032159 A2 for the entry and withdrawal of the energy from the storage tank, which leads to a high mechanical and electrical expense.

From EP 2 322 880 A1, a heat pump system is known in which at least two structurally separate heat pumps are connected to a single environmental heat source circuit, wherein in the latter various environmental heat sources can be integrated.

From DE 3 101 138 A1 a heat pump is known, in which the heat energy of two heat sources of the evaporator side via a triple heat exchanger is supplied individually or simultaneously.

The present invention will now be explained with reference to preferred embodiments and with reference to the drawings.

Fig. 1 shows a flow chart of a heating and / or cooling system (10), on whose Pri märenergiespeicher (1) the inventive method is used, Fig. 2 shows a preferred variant of the Luftsolewärmetauschers (3) relationship, respectively a heat exchanger module (3a) in a schematic representation, Fig. 3 shows a preferred variant of the ground collector (2) or a

Collector module (2a) in a schematic representation.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Fig. 1 shows a flow chart of the heating and / or cooling system (10), on the primary energy storage (1), the inventive method is applied. The elementary primary circuit (8) contains the brine pump (6), the ground collector (2) and the primary heat exchanger (5) of the brine water heat pump (4). In the extended primary circuit (8a), an air-oil heat exchanger (3) is additionally contained, the latter being connected in series into the brine circuit by a switching element (9), in particular by a change-over valve. In the secondary circuit of the brine heat pump (4) a consumer (7) is included, to which the recovered heat and / or cold is released. In the event that with the same brine heat pump (4) in the warm season cold and in the cold season heat is to be generated, this must be designed as a reversible heat pump. For heat pumps of this type, a four-way valve simply swaps the evaporator and condenser in the refrigerant circuit; Usually two different expansion valves are also used for optimum adaptation to the two operating modes. However, these details are not shown in the schematic representation of the heat pump (4) in Fig. 1, because they are irrelevant to the inventive method.

In principle, the brine heat pump (4) for each of the two main modes (heating and cooling) can be operated in each of three sub-modes. These are: [0014] a. Operation of the heat pump (4) with elementary primary circuit (8) (operating mode B1) b. Operation of the heat pump (4) with extended primary circuit (8a) (mode B2), c. Operation of the brine pump (6) with the heat pump (4) and extended primary circuit (8a) deactivated (operating mode B3).

In the operating mode B1, the primary energy is taken exclusively from the primary energy storage (1). The heating and / or cooling system (10) can be converted into the operating mode B2, if (a) in the heating mode, the air temperature is greater than the temperature of the storage medium (31b) of the primary energy storage (1) or (b) in the cooling mode, the air temperature less represents the temperature of the storage medium (31b) of the primary energy storage (1). In the operating mode B2, at least part of the primary energy is then removed from the ambient air via the air-oil heat exchanger (3), but it may also be the case that the entire primary energy requirement is taken from the ambient air and, in addition, regeneration of the primary energy store (1 ) comes. This case occurs when there is a significant temperature difference between ambient air (31a) and the storage medium (31b) of the primary energy store (1). Is in the heating mode, for example, the air temperature (31a) ΙΟ'Ό and the temperature of the storage medium (31b) 0 ° C, and regulates the heat pump (4) the spread of the brine temperature to 4 Kelvin, could with appropriate dimensioning of Luftsolewärmetauscher (3) and earth collector (2) set the following temperature conditions: reference point 1 (30a): 1 ^, reference point 2 (30b): δ'Ό, reference point 3 (30c): 5 ° C. The temperature difference is at Luftsolewärmetauscher (3) thus 8 ° C - 1 <€ = 7K, at the ground collector (2) - 8 ^ = -3K and at the primary heat exchanger (5) 5 ° C - 1 ° C = 4K. In other words, all of the energy obtained at the air-oil heat exchanger (3) goes to the heat pump (4) and from there on to the consumer (7) and 3/7 of the recovered energy in the regeneration of the primary energy store (1).

On the basis of the above example calculation it is also clear that it can be advantageous to change from operating mode B1 to operating mode B2 even when the air temperature (31a) is lower than the temperature of the storage medium (31b) the strategy of the heat pump control to produce a temperature spread of the brine of 4K at the primary heat exchanger (5) results in a brine outlet temperature (reference point 1 (30a)) which is at least 4K lower than the temperature of the storage medium (31b). If the air temperature (31a) between the temperature of the storage medium (31 b) and said brine outlet temperature (30a), it comes in B2 at the Luftsolewärmetauscher (3) in any case to a temperature increase of the brine and thus to a heat input, thereby the primary energy storage (1) is spared in comparison to the operating mode B1.

The mode B3 is activated when the consumer (7) currently no heat or cooling demand is given, the air temperature (31a) (a) in heating but greater than the temperature of the storage medium (31b) in the primary energy storage (1) or (b) is smaller than the latter in the cooling mode. By the brine flow it comes (a) in heating mode to heat absorption on Luftsolewärmetauscher (3) and heat dissipation at the ground collector or (b) in the cooling mode to a cold absorption on Luftsolewärmetauscher and a cooling discharge to the ground collector (2), whereby in both main modes regeneration of the primary energy store (1) is given.

The storage medium of the primary energy storage (1) should have a high water content, especially in heating mode. The enormous melting enthalpy (333.5 kJ / kg) of the water ensures that the entire primary energy storage (1) can remain at a temperature level of 0 ° C (freezing / melting point water) for a long time. Thus, during periods of warm weather during the heating season (for example in Föhnwetterlagen) due to the high temperature differences between air and storage medium to large energy inputs, which do not weaken even in long periods of warm weather, because a temperature increase in the memory only after a complete melting of the Ice is possible. If the molten water remains in the primary energy storage device (1), the heat input is available again for subsequent cold phases, whereby even long periods of cold can be bridged at a temperature level of the storage medium of 0 ° C.

With regard to the second main operating mode (cooling), large temperature differences between day and night occur in many regions of the world. But even in the temperate zones of Central Europe, temperatures of 35 ° C are often reached on summer days, while temperatures drop to below 20 ° C during the night. The method according to the invention now makes it possible to emit the heat accumulating during the cooling process during the day against the relatively cool storage medium of the primary energy store (1). During the night, the now warm primary energy storage tank (1) is discharged via the air-oil heat exchanger (3) against the cold outside air. This anticyclical mode of operation allows considerably better numbers of jobs (EER) to be realized than would be possible with a direct release of the heat to the hot outside air of the day. For example, reversible brine heat pumps for operating point "B20 / W7" (brine: 20 ° C, water: 7 ^) achieve operating figures (EER) of 6.4 and more. If this value is compared with reversible air-source heat pumps, the operating figures (EER) for the operating point "A35 / W7" (air: 35 ° C, water: 7 ° C) rarely exceed the value of 3.30. Another advantage of the method according to the invention is that a brine is used as the heat transfer medium and not a gaseous refrigerant, as is the case with air-water heat pumps, whereby the construction and maintenance of the systems is substantially simplified. In addition, the numbers of brine water heat pumps are generally better than those of air water heat pumps.

Fig. 2 shows a preferred variant of the Luftsolewärmetauschers (3). This consists of a plurality of metallic core tubes (11), which are thermally conductively connected to a plurality of likewise metallic lamellae (12). The lamellae (12) are preferably arranged in a normal plane of the core tube axes, wherein the core tubes (11) are first connected in series to subsole circuits (11b) and then parallel to a Gesamttsolekreis with two brine collector terminals (13). The serial interconnection of the core tubes (11) to subsole circles (11b) is carried out by elbows, which are also referred to as hairpins (11a). The parallel connection of the sub-loop circuits (11b) to the total closed loop circuit takes place via manifolds (14). The preferred material for the fins (12) is aluminum, the preferred material for the core tubes (11), hairpins (11a) and headers (14) is aluminum or copper. Copper has the advantage that it is easy to process by soldering, aluminum must be welded, but is less expensive. Core tubes (11), fins (12), hairpins (11 a) and manifolds (14) are prefabricated in the prior art by the refrigeration industry in large numbers for evaporators and condenser, which is also favorable production costs for the Luftsolewärmetauscher (3) of the invention Procedure result.

The Luftsolewärmetauscher (3) is designed in its preferred embodiment for operation with natural air movement. This saves the use of fans and prevents noise emissions. The smaller area-specific power is easily compensated by a larger area. To prevent the risk of a continuous icing of the slats in the heating mode, the slats (12) are spaced at 5 mm. In general, the risk of icing up is greatly reduced anyway, because at low temperatures the air-oil heat exchanger (3) is not integrated in the primary circuit of the heat pump (4) at all.

In a preferred embodiment of the Luftsolewärmetauschers (3) this is also modular, with the total heat exchanger preferably from the hydraulic parallel circuit of the collector modules (3a) composed. This ensures easy deployment of the system. A collector module (3a) preferably has dimensions of about 2 m x 1 m (length x height) and then weighs about 30 kg in an aluminum version. So it is still easy to handle, in an emergency by a single man. The slat width or the module depth is about 50 mm. An even greater lamella width would no longer develop a decisive increase in performance with an assumed frontal speed of the air of about 0.15 m / s (natural air movement) and the above-mentioned spacing of the lamellae. Under the assumptions made, the air-oil heat exchanger (3) can be assumed to have a specific power of about 140 watts per square meter and degrees Kelvin of mean temperature difference between brine and air. This value can also be verified well in practice. He already takes into account that in the open air there is practically never complete calm, and the natural air movement enhances the heat exchange between air and brine. On the other hand, if the air-oil heat exchanger really is "in the wind", specific outputs of 500 W / (m2 * K) are also possible (front air flow rate of the air: 1.0 m / s).

Fig. 3 shows a preferred variant of the ground collector (2) or a collector module (2a). As with the air-oil heat exchanger (3), the earth collector (2) is preferably formed by the hydraulic parallel connection of individual collector modules (2a). A collector module (2a) is designed as a tube heat exchanger, wherein a PE tube (15) is laid helically in a horizontal plane so that the tube turns in a first, lower layer of a connection point (16) with the two brine connections (17 ) and return to this in a second, upper layer.

A persistently high water content in the storage medium of the primary energy store (1) is preferably ensured by the following two variants: [0025] a. If the soil consists of soils that have a high water content also against the

Gravity can hold (adhesively bonded adhesive water and closed micro cavities), the earth collector can be introduced directly into the ground. For example, clay or clay soils can easily hold 0.25 liters of water and more per cubic decimeter. If such floors are present, the tubes of the ground collector (2) may be laid so tightly in an application of the method according to the invention that results in withdrawal rates of 100 W / m2 and more. Usually, in a surface collector, a floor, depending on the type of soil, not more than 10 - 35 W / m2 withdrawn, because the soil otherwise thermally exhausted during the heating period or can no longer completely regenerate between the heating periods. Due to the thermal regeneration of the soil within the heating season, the withdrawal rate can be chosen much larger. As a rule of thumb, for moderate climates with not more than 4,000 degree days per annum (according to VDI 3807, for example Vienna: 3,235 Kd / a, Berlin: 3,606 Kd / a, Munich: 3,809 Kd / a), the area required for the collector to one quarter of a Conventional surface collector can be reduced if, for an annual heating demand of 2,500 kWh in each case one square meter Luftsolewärmetauscher (3) is provided in the above-mentioned embodiment. If, for example, a building has an annual heating demand of 10,000 kWh and a surface area requirement of 240 m2 has been calculated for a conventional surface collector, the area requirement can be reduced to 60 square meters if the air-oil heat exchanger (3) has an area of 4m2. Of course, only the area required and not the tube length of the collector can be reduced. The latter now preferably has to be concentrated in the variant proposed in FIG. 3 onto the smaller area. The reduction of the collector area to 1/4 the size of a conventional surface collector means that there is a turnover rate of the energy contained in the primary storage of 4, based on a heating period. At a reference plant (3,340 Kd / a), a turn over frequency of 10 (but for a gravel / water reservoir) was successfully tested, so you should be on the safe side with the design proposed above.

B. In sandy or gravel soils, a high water content of the primary energy storage (1) can be ensured by the introduction of a waterproof film in the soil. As a filler, a round gravel is preferably used, because this does not violate the PE pipes (15) of the ground collector (2) or the film. This variant also has the advantage that excess storage water in the removal of heat (and the associated freezing process) can be easily pushed up and derived there defined. This results in no soil elevations, which makes this variant is particularly suitable for sealed surfaces.

A further preferred embodiment of the method according to the invention relates to the fact that the switching element (9) for integrating the Luftsolewärmetauschers (3) in the primary circuit of the brine heat pump (4) is done manually. This is particularly useful for existing systems, if it turns out that the area of the surface collector was chosen too low and an additional regeneration outside the heating period is desired. The heating and regeneration periods can also overlap; In Germany, for example, the months April to October offer continuous activation of the air-oil heat exchanger (3) due to the still very positive average temperatures. By the manual operation of the switching element (9), the electrical control of an existing system requires no modification.

The performance of a regeneration outside the heating period will now be demonstrated by means of a calculation example: If at the end of the heating season, a large part of the soil frosted around the PE pipes of the collector, it can be assumed that the temperature of the storage medium practically on the entire regeneration period remains at 0 ° C. (If the ice melted completely earlier, then one may well enjoy this circumstance!) If it is further assumed that at a for this application very small (in terms of heat transfer and in relation to the earth collector (2) ) dimensioned Luftsolewärmetauscher (3) de facto the entire temperature rise of

Brine in the earth collector (2) can be reapplied, calculated over the assumed regeneration period of 7 months (April to October), an average air temperature of 14 ° C in this period (Germany, average 2001-2013) and a specific performance of the Air heat exchanger of 140 W / (m2 * K) a heat input of 14 K * 210 d / a * 24 h / d * 0.14 kW / (m2 * K) = 10,580 kWh / (m2 * a).

This is about seven times (!) The average annual solar irradiation in Germany [1,400 kWh / (m2 * a)]. With regard to the regeneration of a low-temperature storage medium, the air-oil heat exchanger (3) proposed in the method according to the invention is therefore far superior to a solar collector, which opens up an interesting point of view, in particular with regard to the proposals of EP 2 246 633 A2 and EP 2 151 637 A2.

REFERENCE IDENTIFICATION 1 Primary energy storage 2 Earth collector 2a Collector module 3 Air solar heat exchanger 3a Heat exchanger module 4 Brine heat pump 5 Primary heat exchanger 6 Brine pump 7 Consumers 8 Elementary primary circuit 8a Extended primary circuit 9 Changeover element 10 Heating / cooling system 11 Core tube 11 a Hairpin 11b Subsole circle 12 Slat 13 Solesammelanschluss 14 Collector pipe 15 Polyethylene pipe (PE) Pipe) 16 Junction 17 Brine collector 30a Reference point 1: Brine temperature Heat pump outlet 30b Reference point 2: brine temperature Air-cooled heat exchanger 30c reference point 3: brine temperature outlet earth collector 31 a reference point 4: ambient air temperature 31 b reference point 5: temperature storage medium

Claims (9)

1. A method for regenerating the primary energy storage (1) of a heating and / or cooling system (10), consisting of (a) a brine heat pump (4) with a connected to her heat and / or refrigeration consumer (7), (b) a primary energy storage device (1) having a ground collector (2), (c) a brine pump (6) for transporting a heat transfer medium (brine) through the primary circuit (8), characterized in that in at least one operating mode by means of a changeover element (9) additionally Air solar heat exchanger (3) is connected in series in the primary circuit (8), and a. in the event that the brine heat pump (4) is configured to deliver heat to the consumer (7), the brine pump (6) is activated even if the brine circuit of the brine heat pump (4) is deactivated, if the air temperature (31a) is greater than Represents temperature of the storage medium (31b) in the primary energy storage (1), and / or b. for when the brine heat pump (4) is configured to deliver refrigeration to the consumer (7), the brine pump (6) is activated even with the brine circuit heat pump (4) deactivated, when the air temperature (31a) is less than represents the temperature of the storage medium (31b) in the primary energy storage (1). 2. Heating and / or cooling system (10) for carrying out a method according to claim 1, characterized in that the Luftsolewärmetauscher (3) (or a module (3a) of a modular Luftsolewärmetauschers (3)) by a plurality of metallic core tubes ( 11) is formed in a heat-conducting manner with a multiplicity of likewise metallic lamellae (12), wherein the lamellae (12) are preferably arranged in a normal plane of the core tube axes and the core tubes (11) parallel and / or serially to a brine circuit having at least two brine collector connections (11). 13) are interconnected. 3. heating and / or cooling system (10) according to claim 2, characterized in that the Luftsolewärmetauscher (3) is designed for operation with only natural air movement. 4. heating and / or cooling system (10) according to any one of claims 2 to 3, characterized in that the ground collector (2) or a module (2 a) of a modular Erdkollektors (2) from a spirally laid in a horizontal plane PE -Tube (15) is formed, wherein the pipe turns in a first position of a connection point (16) with the two brine connections (17) remove and return to this in a second position. 5. Heating and / or cooling system (10) according to any one of claims 2 to 4, characterized in that the storage medium of the primary energy storage (1) is formed by the soil, wherein the soil is such that it is at least 0.25 liters Water per cubic decimeter soil can hold against gravity, as is particularly true in loam or clay soils. 6. heating and / or cooling system (10) according to one of claims 2 to 5, characterized in that the ground collector (2) of the primary energy storage (1) is dimensioned so that the heat and / or cold extraction power at least 50 watts per square meter Collector area is. 7. heating and / or cooling system (10) according to any one of claims 2 to 6, characterized in that the primary energy storage (1) is formed by a gravel storage filled with water, wherein the gravel storage is sealed by a waterproof shell against the soil. 8. heating and / or cooling system (10) according to one of claims 2 to 7, characterized in that the primary energy storage (1) is designed as a latent heat storage with the storage medium water. 9. heating and / or cooling system (10) according to any one of claims 2 to 8, characterized in that the switching member (9) in particular with regard to a regeneration of the primary energy storage (1) outside or predominantly formed outside the heating period for a manual operation is. For this 2 sheets of drawings