(12) Oversettelse av europeisk patentskrift

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1 (12) Oversettelse av europeisk patentskrift (11) NO/EP 927 B1 (19) NO NORGE (1) Int Cl. F24D 19/ (06.01) Patentstyret (21) Oversettelse publisert (80) Dato for Den Europeiske Patentmyndighets publisering av det meddelte patentet (86) Europeisk søknadsnr (86) Europeisk innleveringsdag (87) Den europeiske søknadens Publiseringsdato (30) Prioritet , AT, (84) Utpekte stater AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR (73) Innehaver Vaillant GmbH, Berghauser Strasse 40, 4289 Remscheid, DE-Tyskland (72) Oppfinner Bahlmann, Hermann-Josef, Kathener Dorfstr. 14, Lathen, DE-Tyskland Hiegemann, Markus, Im Hole 6, Bochum, DE-Tyskland Lebernegg, Martin, Remscheider Str. 27, 428 Remscheid, DE-Tyskland Schäfer, Christaian, Tefentaler Str. 13, Remscheid, DE-Tyskland Schöps, Axel, Langenfelder Str. 23a, 1371 Leverkusen, DE-Tyskland (74) Fullmektig Bryn Aarflot AS, Postboks 449 Sentrum, 04 OSLO, Norge (4) Benevnelse Method for operating a heat pump with an air-brine heat exchanger in a brine circuit (6) Anførte publikasjoner EP-A EP-A AT-A DE-A

2 1 1 2 The invention relates to a method for operating a heat pump with an air-to-brine heat exchanger in a brine circuit. By means of air-to-brine heat exchangers heat pumps can be provided with environmental heat at a very low temperature level. In compression heat pumps the refrigerant in the heat pump circuit is cooled to temperatures of below -1 C. Thus even at an external temperature of -1 C heat can be removed from the environment and transmitted in the compressor to the heat pump circuit. The power of the heat pump increases with the temperature of the environment, whilst at the same time the heat requirement drops. Thus at high environmental temperatures the heat pump can be operated cyclically or in a modulating manner. Conversely, the heat pump can only cover the heat requirement up to a specific environmental temperature. Below this temperature, which is typically - C to - C (so-called bivalence point), it is possible according to the prior to introduce additional heat into the heating circuit by means of a second heat generator, for example an electrically operated additional heater in bivalent operation. If the environmental temperature lies below the application limit temperature of the heat pump (usually -2 C to - C), it forces the heat pump to be switched off.

3 The heat supply is then only provided by the second heat generator, which is generally undersized for this purpose. US shows a heat pump with an air-heat exchanger, in which a ventilator blows air between two heat exchanger plates and thereby enables a transfer of heat from the environmental air to the heat exchanger plates. If the external temperature is so low that no heat can be transmitted from the external air to the heat exchanger, thus a fuel gas operated burner is switched on, the waste gases of which flow through the aforementioned heat exchanger. The burner is thus used for heating the external air or for replacing cold external air with hot waste gases. Publication DE A1 discloses a method for de-icing the air-to-brine heat exchanger of a heat pump system, in which the air-to-brine heat exchanger is heated by an electric heat source when the compressor if switched off. Publications EP A2 and AT A1 disclose methods for operating a heat pump system in which various different environmental heat sources are used as a function of the measured environmental temperature. Thus the underlying objective of the invention is to create a method for operating a heat pump with an air-to-brine heat exchanger, which also enables the operation of the heat pump even at very low external temperatures. According to the invention this is achieved by a method with the features of the independent claim.

4 Accordingly, in a heat pump with a brine circuit, in which an air-to-brine heat exchanger and a circulation pump are located, the environmental temperature of the air is determined. If this falls below a predefined limit value the fan of the air-to-brine heat exchanger is switched off and a heating element in the brine circuit is switched on. By switching off the fan a transfer of heat to the environment is avoided so that then the compressor of the heat pump is supplied with heat by means of the heating power of the heating element. Advantageous embodiments are defined in the features of the dependent claims. The invention is explained in the following with reference to the Figures. In the latter Figure 1 shows a device for performing the method according to the invention and Figure 2 shows the connection between the heat requirement and heating power of the heat pump to the environmental temperature and Figure 3 shows the brine temperature and the operating state of the heating element during the method according to the invention. Figure 1 shows a brine circuit 4 of a heat pump 12 with an air-to-brine heat exchanger 3, which has a fan 7 for conveying environmental air through the airto-brine heat exchanger 3. In the brine circuit 4 there is also a circulation pump. The brine circuit 4 is connected via a compressor 6 to the heat pump 12. A first temperature sensor 1 for detecting the environmental air temperature TU is arranged on the

5 air inlet side of the air-to-brine heat exchanger 3. A second temperature sensor 2 is positioned in the brine circuit 4 for detecting the temperature of the brine TS,W downstream of the air-to-brine heat exchanger 3. A heating element 8 is arranged directly upstream of the air-to-brine heat exchanger 3 in the brine circuit 4. The heat pump 12 is set up in a house. Through the house wall 11 the brine circuit 4 leads to the air-to-brine heat exchanger 3. A third and a fourth temperature sensor 9, are arranged in the brine circuit 4 downstream and upstream of the compressor 6 respectively. During the normal operation of the heat pump 12 the circulation pump is in operation. At least temporarily the environmental air temperature TU and the temperature of the brine TS,W is detected downstream of the air-to-brine heat exchanger 3. As long as the air-to-brine heat exchanger 3 is not fully iced up, the brine can absorb heat from the environment. Ideally the brine would absorb the environmental temperature; however due to the finite heat exchanger surface the brine always remains slightly colder. If the air-to-brine heat exchanger 3 ices up, the temperature difference ΔT between the environmental air temperature TU and the temperature of the brine TS,W downstream of the air-to-brine heat exchangers 3 increases. The more iced up the air-tobrine heat exchanger 3 the greater the temperature difference ΔT. Figure 2 shows as a function of the environmental air temperature TU the power Q of the heat pump and

6 the heat requirement QSoll of the house. As already mentioned above, the power Q of the heat pump increases with the temperature of the environment, whereas at the same time the heat requirement QSoll drops. At the so-called bivalence point (temperature TB) the power Q of the heat pump corresponds to the heat requirement QSoll of the house. Below this bivalence temperature TB the second heat generator 13 is switched on so that the heat pump can continue to be operated otherwise unchanged. Thus depending on the dimensions up to the standard external temperature TN the heat requirement QSoll of the house can be covered. The method according to the invention is used below the standard external temperature TN, as below this temperature when operating the fan 7 heat would be emitted via the air-to-brine heat exchanger 3 to the environment. When the circulation pump is switched on the heating element 8 is operated and thus heat is provided to the compressor 6 of the heat pump 12 at a temperature level which permits the operation of the heat pump and increases the heating power of the heat pump. The release of heat to the environment is prevented according to the invention by switching off the fan 7, so that the brine circuit is now heated solely by the heating element 8. The heating requirements QSoll of the house are then no longer completely covered, but at least the operation of the heat pump is possible to satisfy a portion of the heat requirement QSoll, which would otherwise not be the case. Below freezing temperature TF the heat losses of the brine circuit are so great that sufficient heat no

7 6 1 longer reaches the compressor 6 for operating the heat pump. Figure 3 shows the brine temperature in the operating range below the standard external temperature TN. The heating element 8 is then operated only cyclically, as the whole heating power of the heating element 8 is not required and it is thus ensured that the brine circuit 4 is only heated so much that it does not drop below the temperature limit for use TF. The invention is not only limited to compression heat pumps. For example according to the invention also an air-to-brine heat exchanger of a sorption heat pump can be de-iced. The heating element 8 can be arranged downstream or upstream of the air-to-brine heat exchanger 3. Upstream of the air-to-brine heat exchanger 3 it can be used more effectively for de-icing the air-to-brine heat exchanger 3, and downstream it can heat the brine more efficiently.

8 7 List of reference numerals first temperature sensor 1 second temperature sensor 2 air-to-brine heat exchanger 3 brine circuit 4 circulation pump compressor 6 fan 7 heating element 8 third and fourth temperature sensor 9, house wall 11 heat pump 12

9 8 P A T E N T K R A V 1 1. Fremgangsmåte for drift av en varmepumpe (12) med en saltvannskrets (4), i hvilken er sirkulasjonspumpe (), en luft-til-saltvannsvarmeveksler (3), en kompressor (6) og et varmeelement (8) er plassert, for deteksjon av den omgivende lufttemperatur Tu ved hjelp av første temperatursensor (1), hvori luft-til-saltvannsvarmeveksleren (3) besitter en vifte (7) for å transportere omgivelsesluft gjennom luft-tilsaltvannsvarmeveksleren (3), k a r a k t e r i s e r t v e d a t omgivelseslufttemperaturen Tu registreres ved hjelp av en første temperatursensor og, når en forhåndsbestemt temperatur TN er sunket under, slås viften (7) av og varmeelementet (8) slås vekselvis på og av, slik at det sikres at saltvannskretsen (4) kun oppvarmes til den grad at en bruksterskeltemperatur TF, under hvilken varmetapene av saltvannskretsen blir så stor at tilstrekkelig varme ikke lenger kommer til kompressoren (6) for operasjonen av varmepumpen, ikke senkes nedenfor. 2. Fremgangsmåte for operasjonen av en varmepumpe ifølge krav 1, k a r a k t e r i s e r t v e d a t temperaturen TN er temperaturen under hvilken varmekravet QSol til et hus som skal oppvarmes av varmepumpen (12) ikke lenger er i stand til å dekkes av varmepumpen og en påslått andre varmegenerator (13) Fremgangsmåte for operasjonen av en varmepumpe ifølge et av de foregående krav, hvori varmeelementet (8) anordnes nedstrøms av luft-til-saltvannsvarmeveksleren (3).

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