Heating system

Abstract

The invention refers to a heating system (100) comprising a district cooling grid (1) and a local heating system (200) configured to heat a building and/or to heat tap water for the building. The heating system has a feed conduit (5) for an incoming flow of cooling fluid having a first temperature, and a return conduit (8) for a return flow of cooling fluid having a second temperature, the second temperature being higher than the first temperature. The local heating system (200) comprises a heat pump (10) having an inlet (10a) connected to the return conduit (8) of the district cooling grid (1) and an outlet (10b) connected to the feed conduit (5) of the district cooling grid (1).

Claims

1. A heating system comprising: a district cooling grid used to satisfy comfort cooling demands, the district cooling grid having: a feed conduit conducting an incoming flow of a cooling fluid in a form of water, anti-freezing liquids or mixtures thereof, the incoming flow of cooling fluid having a first temperature in the range of 4-12 C., a return conduit conducting a return flow of the cooling fluid, the return flow of cooling fluid having a second temperature, the second temperature being higher than the first temperature, and the second temperature being in the range of 10-18 C., a district cooling plant which cools the cooling fluid of the return conduit from the second temperature to the first temperature, and a plurality of consuming cooling devices each configured to consume cooling of the cooling fluid entering the consuming cooling device and to heat the cooling fluid, the heated cooling fluid being output to the return conduit, wherein the cooling fluid is circulated in the district cooling grid by means of a pressure difference between the feed conduit and the return conduit, and the pressure in the feed conduit is higher than the pressure in the return conduit; and a local heating system of a building configured to heat the building and/or to heat tap water for the building, wherein the local heating system of the building comprises: a heat pump having an inlet connected to the return conduit of the district cooling grid and an outlet connected to the feed conduit of the district cooling grid, a pump arranged in the inlet or in the outlet of the heat pump, and configured to overcome the pressure difference between the return conduit and the feed conduit, a temperature sensor configured to determine data pertaining to a temperature of the cooling fluid in the outlet of the heat pump, and a controller configured to control the pump to regulate the flow of cooling fluid flowing through the heat pump based on the data pertaining to the temperature of the cooling fluid in the outlet.

2. The heating system according to claim 1, wherein the local heating system of the building further comprises a heat emitter and a heat demand sensor configured to determine data pertaining to heating demands of the heat emitter, and the controller is configured to control the pump based on the data pertaining to heating demands of the heat emitter.

3. The heating system according to claim 1, wherein the controller is further configured to control operation of the heat pump.

4. The heating system according to claim 1, wherein the pump is arranged in the inlet of the heat pump.

5. The heating system according to claim 1, wherein the pump is arranged in the outlet of the heat pump.

6. The heating system according to claim 1, wherein the feed and return conduits are plastic un-insulated conduits.

7. A method for controlling heat outtake from a district cooling grid used to satisfy comfort cooling demands, the district cooling grid comprising a feed conduit conducting an incoming flow of a cooling fluid in a form of water, anti-freezing liquids or mixtures thereof, the incoming flow of cooling fluid having a first temperature in the range of 4-12 C., a return conduit conducting a return flow of the cooling fluid, the return flow of cooling fluid having a second temperature, the second temperature being higher than the first temperature, the second temperature being in the range of 10-18 C.; a district cooling plant which cools the cooling fluid of the return conduit from the second temperature to the first temperature; and a plurality of consuming cooling devices each configured to consume cooling of the cooling fluid entering the consuming cooling device and to heat the cooling fluid, the heated cooling fluid being outputted to the return conduit, wherein the cooling fluid is circulated in the district cooling grid by means of a pressure difference between the feed conduit and the return conduit, the pressure in the feed conduit is higher than the pressure in the return conduit, and the heat outtake is performed via a heat pump having an inlet connected to the return conduit of the district cooling grid and an outlet connected to the feed conduit of the district cooling grid, the method comprising: determining data pertaining to a temperature of the cooling fluid in the outlet of the heat pump; and controlling a pump arranged in the inlet or in the outlet of the heat pump to regulate the flow of cooling fluid flowing through the heat pump based on the data pertaining to the temperature of the cooling fluid in the outlet of the heat pump.

8. A method for controlling heat outtake from a district cooling grid used to satisfy comfort cooling demands, the district cooling grid comprising a feed conduit conducting an incoming flow of a cooling fluid in a form of water, anti-freezing liquids or mixtures thereof, the incoming flow of cooling fluid having a first temperature in the range of 4-12 C., a return conduit conducting a return flow of the cooling fluid, the return flow of cooling fluid having a second temperature, the second temperature being higher than the first temperature, the second temperature being in the range of 10-18 C.; a district cooling plant which cools the cooling fluid of the return conduit from the second temperature to the first temperature; and a plurality of consuming cooling devices each configured to consume cooling of the cooling fluid entering the consuming cooling device and to heat the cooling fluid, the heated cooling fluid being outputted to the return conduit, wherein the cooling fluid is circulated in the district cooling grid by means of a pressure difference between the feed conduit and the return conduit, the pressure in the feed conduit is higher than the pressure in the return conduit, and the heat outtake is performed via a heat pump having an inlet connected to the return conduit of the district cooling grid and an outlet connected to the feed conduit of the district cooling grid, wherein the heat pump is connected to a heat emitter, the method comprising: determining data pertaining to heating demands of the heat emitter, and controlling a pump arranged in the inlet or in the outlet of the heat pump to regulate the flow of cooling fluid flowing through the heat pump based on the data pertaining to heating demands of the heat emitter.

9. A heating system comprising: a district cooling grid used to satisfy comfort cooling demands, the district cooling grid having: a feed conduit conducting an incoming flow of a cooling fluid in a form of water, anti-freezing liquids or mixtures thereof, the incoming flow of cooling fluid having a first temperature in the range of 4-12 C., a return conduit conducting a return flow of the cooling fluid, the return flow of cooling fluid having a second temperature, the second temperature being higher than the first temperature, and the second temperature being in the range of 10-18 C., a district cooling plant which cools the cooling fluid of the return conduit from the second temperature to the first temperature, and a plurality of consuming cooling devices each configured to consume cooling of the cooling fluid entering the consuming cooling device and to heat the cooling fluid, the heated cooling fluid being output to the return conduit, wherein the cooling fluid is circulated in the district cooling grid by means of a pressure difference between the feed conduit and the return conduit, and the pressure in the feed conduit is higher than the pressure in the return conduit; and a local heating system of a building configured to heat the building and/or to heat tap water for the building, wherein the local heating system of the building comprises: a heat pump having an inlet connected to the return conduit of the district cooling grid and an outlet connected to the feed conduit of the district cooling grid, a pump arranged in the inlet or in the outlet of the heat pump, and configured to overcome the pressure difference between the return conduit and the feed conduit, a heat emitter and a heat demand sensor configured to determine data pertaining to heating demands of the heat emitter, and a controller configured to control the pump to regulate the flow of cooling fluid flowing through the heat pump based on the data pertaining to heating demands of the heat emitter.

10. The heating system according to claim 9, wherein the controller is further configured to control operation of the heat pump.

11. The heating system according to claim 9, wherein the pump is arranged in the inlet of the heat pump.

12. The heating system according to claim 9, wherein the pump is arranged in the outlet of the heat pump.

13. The heating system according to claim 9, wherein the feed and return conduits are plastic un-insulated conduits.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiments of the invention. The figures are provided to illustrate the general structures of embodiments of the present invention. Like reference numerals refer to like elements throughout.

(2) FIG. 1 is a schematic diagram of a prior art district cooling grid interacting with buildings, each having a local cooling system.

(3) FIG. 2 is a schematic diagram of the inventive heating system.

DETAILED DESCRIPTION

(4) The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and to fully convey the scope of the invention to the skilled person.

(5) Starting with FIG. 1 the general design of a district cooling grid interacting with a building having a local cooling system will be discussed.

(6) Starting with FIG. 1 a district cooling grid 1 as such is well known in the art and is formed by one or several hydraulic networks (not disclosed) that deliver a cooling fluid to local cooling systems 3 which are arranged in buildings 2 such as office buildings, business premises, residential homes and factories in need for cooling. A typical district cooling grid 1 comprises a district cooling plant 4 which cools the cooling fluid. The district cooling plant may by way of example be a power plant using lake water. The cooled cooling fluid is transported via a feed conduit 5 forming part of a conduit network 6 to locally distributed consuming cooling devices 7 which are arranged in the buildings 2. It goes without saying that one and the same building 2 may comprise several consuming cooling devices 7. Examples of consuming cooling devices 7 are air-conditioners and refrigerators.

(7) When the cooling of the cooled cooling fluid is consumed in the consuming cooling devices 7 the temperature of the cooling fluid is raised and the thus heated cooling fluid is returned to the district cooling plant 4 via a return conduit 8 forming part of the conduit network 6.

(8) District cooling grids 1 are used to satisfy comfort cooling demands. The temperature of the cooling fluid in the feed conduits 5 is typically between 4-12 C. The return temperature in the return conduits 8 is typically between 10-18 C.

(9) The driving pressure difference between feed conduits and return conduits of the hydraulic network always creates a so called pressure cone whereby the pressure in the feed conduits 5 is higher than the pressure in the return conduits 8. This pressure difference circulates the cooling fluid in the hydraulic network between the district cooling plant and the cooling consumption devices.

(10) The conduits used in a district cooling grid 1 are normally plastic un-insulated conduits designed for a maximum pressure of either 0.6 or 1 MPa and maximum temperature of about 50 C. Also, the cooling fluid and hence energy carrier is typically water, although it is to be understood that other fluids or mixture of fluids may be used. Some non-limiting examples are ammonia, anti-freezing liquids (such as glycol), oils and alcohols. A non-limiting example of a mixture is water with an anti-freezing agent, such as glycol, added thereto. The energy content of the returned cooling fluid is according to prior art considered as waste energy.

(11) Reference is now made to FIG. 2 which schematically discloses the inventive heating system 100. In its broadest sense the heating system 100 comprises a district cooling grid 1, a local heating system 200 of a building 2 and a heat pump 10. The district cooling grid 1 has the same design as previously described with reference to FIG. 1 and to avoid undue repetition, reference is made to the sections above describing the district cooling grid 1.

(12) The local heating system 200 is a heating system using a circulating heating fluid such as water, although it is to be understood that other fluids or mixture of fluids may be used. Some non-limiting examples are ammonia, anti-freezing liquids (such as glycol), oils and alcohols. A non-limiting example of a mixture is water with an anti-freezing agent, such as glycol, added thereto. The local heating system comprises a heat emitter 12. Heat emitters 12 are as such well known in the art. The heat emitter 12 may be used e.g. for comfort heating buildings such as office buildings, business premises, residential homes and factories, and/or to heat tap water. Examples of typical heat emitters 12 are hydraulic radiator systems, hydraulic floor heating systems, air convectors with hydraulic heating coils and heating batteries with hydraulic heating coils arranged in ventilation systems supply air ducts. It goes without saying that one and the same building 2 may comprise several heat emitters 12.

(13) The heat emitter 12 is connected to the district cooling grid 1 via a heat pump 10. A heat pump 10 as such is well known in the art. The heat pump 10 comprises a closed circuit 13 in which a brine is circulated between a first heat exchanger 14 and a second heat exchanger 15. The first heat exchanger 14 has an inlet 10a and an outlet 10b via which the heat pump 10 is connected to a first circuit 13a circulating a flow of a first fluid, in this case the cooling fluid of the district cooling grid 1. Likewise, the second heat exchanger 15 has an inlet and an outlet via which the heat pump 10 is connected to a second circuit 13b circulating a flow of a second fluid, in this case the heating fluid of the local heating system 200. During the circulation, a heat transfer takes place between the brine and the fluids circulating in the first and second circuits 13a, 13b, respectively.

(14) In this context the term inlet 10a of the heat pump is to be interpreted as the inlet in the first circuit 13a via which the heat pump 10 is supplied with the cooling fluid of the district cooling grid 1. Likewise, the term outlet 10b of the heat pump is to be interpreted as the outlet in the first circuit 13a via which the heat pump 10 returns cooling fluid to the district cooling grid 1.

(15) The local heating system 200 may further comprises a pump 16. The pump 16 is configured to overcome the pressure difference between the return conduits 8 and the feed conduit 5. The pump 16 is further configured to regulate the flow of cooling fluid flowing through the heat pump 10. By regulating the flow of cooling fluid trough the heat pump, and at the same time optionally control the operation of the heat pump, the temperature of the cooling fluid returned to the feed conduit 5 may be controlled. The pump 16 may be controlled by a controller 17. The controller 17 may control the pump 16 based on data pertaining to heating demands of the heat emitter 12 and/or data pertaining to the temperature of the cooling fluid in the outlet 10b of the heat pump 10. Data pertaining to heating demands of the heat emitter 12 may be determined by means of a heat demand sensor 18 connected to the heat emitter 12. Data pertaining to the temperature of the cooling fluid in the outlet 10b of the heat pump 10 may be determined by means of a temperature sensor T1 connected to the outlet 10b. In the in FIG. 2 shown embodiment the pump 16 is arranged in the inlet 10a of the heat pump 10. However, the pump 16 may alternatively be arranged in the outlet 10b of the heat pump 10.

(16) The present invention resides in the surprising discovery to use the waste energy accessible in the return conduit 8 of the district cooling grid 1 as a heating source of a building 2, no matter if it is for comfort heating or heating tap water. More precisely, the inlet 10a of the heat pump 10 is connected to the return conduit 8 of the district cooling grid. Thereby the heat energy of the cooling fluid in the return conduit 8 which energy according to prior art is considered as waste energy is used as input to the heat pump 10. The cooling fluid in the return conduit 8 typically has a temperature in the range of 10-18 C.

(17) The outlet 10b of the heat pump 10 is connected to the feed conduit 5 of the district cooling grid 1. Thereby, the cooling fluid delivered as output from the heat pump 10 is supplied to the feed conduit 5 of the local district cooling grid 1 where it intermixes with the flow of cooled cooling fluid. Depending on the settings of the heat pump 10, the temperature of the cooling fluid leaving the heat pump 10 is typically in the range of 4-12 C., i.e. in a range falling within the temperature of the cooling fluid in the feed conduit 5. The flow volume circulated via the heat pump 10 may be minor as compared to the flow volume through the feed conduit 5 whereby any temperature difference between the two flows may be overlooked in terms of heating of the cooling fluid in the feed conduit 5.

(18) The invention provides an environmentally and financially sustainable solution to future engineering projects. The invention allows an existing infrastructure of a district cooling grid to be used not only for cooling but also for heating. In the inventive heating system, the heat energy that is accessible in the return conduit of the district cooling grid and which according to prior art is considered as waste energy is used as input to the heat pump forming part of a local heating system. The heat pump is thereby supplied with a pre-heated fluid whereby the energy consumption of the heat pump may be reduced. This lowers the overall energy cost to operate the building, and also the overall investment in the building. The reduced investment costs reside in the fact that the required designed capacity of the heat pump may be reduced. Likewise, the expected life length of the heat pump may be prolonged.

(19) Variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.