WO2013081532A1 - A system for heating supply air with simultaneous defrosting of a water-exhaust air heat exchanger - Google Patents

A system for heating supply air with simultaneous defrosting of a water-exhaust air heat exchanger Download PDF

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Publication number
WO2013081532A1
WO2013081532A1 PCT/SE2012/051289 SE2012051289W WO2013081532A1 WO 2013081532 A1 WO2013081532 A1 WO 2013081532A1 SE 2012051289 W SE2012051289 W SE 2012051289W WO 2013081532 A1 WO2013081532 A1 WO 2013081532A1
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WO
WIPO (PCT)
Prior art keywords
heat exchanger
water
air
exhaust air
exhaust
Prior art date
Application number
PCT/SE2012/051289
Other languages
French (fr)
Inventor
Martin MELLBIN
Andreas Gustavsson
Adam Fjaestad
Original Assignee
Swegon Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Swegon Ab filed Critical Swegon Ab
Priority to EP12853121.7A priority Critical patent/EP2783165B1/en
Publication of WO2013081532A1 publication Critical patent/WO2013081532A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F3/00—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
    • F24F3/06—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the arrangements for the supply of heat-exchange fluid for the subsequent treatment of primary air in the room units
    • F24F3/08—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the arrangements for the supply of heat-exchange fluid for the subsequent treatment of primary air in the room units with separate supply and return lines for hot and cold heat-exchange fluids i.e. so-called "4-conduit" system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F12/00—Use of energy recovery systems in air conditioning, ventilation or screening
    • F24F12/001—Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air
    • F24F12/002—Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air using an intermediate heat-transfer fluid
    • F24F12/003—Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air using an intermediate heat-transfer fluid using a heat pump
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D11/00—Central heating systems using heat accumulated in storage masses
    • F24D11/02—Central heating systems using heat accumulated in storage masses using heat pumps
    • F24D11/0257—Central heating systems using heat accumulated in storage masses using heat pumps air heating system
    • F24D11/0278—Central heating systems using heat accumulated in storage masses using heat pumps air heating system with recuperation of waste energy
    • F24D11/0285—Central heating systems using heat accumulated in storage masses using heat pumps air heating system with recuperation of waste energy contained in exhausted air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D17/00—Domestic hot-water supply systems
    • F24D17/0005—Domestic hot-water supply systems using recuperation of waste heat
    • F24D17/001—Domestic hot-water supply systems using recuperation of waste heat with accumulation of heated water
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D17/00—Domestic hot-water supply systems
    • F24D17/02—Domestic hot-water supply systems using heat pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/30—Control or safety arrangements for purposes related to the operation of the system, e.g. for safety or monitoring
    • F24F11/41—Defrosting; Preventing freezing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F12/00—Use of energy recovery systems in air conditioning, ventilation or screening
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F12/00—Use of energy recovery systems in air conditioning, ventilation or screening
    • F24F12/001—Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air
    • F24F12/002—Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air using an intermediate heat-transfer fluid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F12/00—Use of energy recovery systems in air conditioning, ventilation or screening
    • F24F12/001—Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air
    • F24F12/006—Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air using an air-to-air heat exchanger
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D2200/00—Heat sources or energy sources
    • F24D2200/12—Heat pump
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D2200/00—Heat sources or energy sources
    • F24D2200/16—Waste heat
    • F24D2200/22—Ventilation air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F2203/00—Devices or apparatus used for air treatment
    • F24F2203/10—Rotary wheel
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B10/00—Integration of renewable energy sources in buildings
    • Y02B10/70—Hybrid systems, e.g. uninterruptible or back-up power supplies integrating renewable energies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/13—Hot air central heating systems using heat pumps
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/18—Domestic hot-water supply systems using recuperated or waste heat
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/52—Heat recovery pumps, i.e. heat pump based systems or units able to transfer the thermal energy from one area of the premises or part of the facilities to a different one, improving the overall efficiency
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/56—Heat recovery units

Definitions

  • the present invention relates to a system for heating supply air, with simultaneous defrosting of a water-exhaust air heat exchanger, when controlling the indoor climate in a building.
  • US2004/0148950 Al discloses an air-conditioning system for a building that comprises a hot water circuit, a cold water circuit and several local air conditioning units.
  • Each of the local air conditioning units comprises a fan for blowing air into a space in the building, a heating coil connected to the hot water circuit and/or a cooling coil connected to the cold water circuit.
  • At least one temperature control system allows control of the heating power of the heating coils and the cooling power of the cooling coils.
  • a calorific energy management system is provided with a heat pump for transferring calorific energy from the cold water system to the hot water system, from the cold water system to the outdoor air and from the outdoor air to the hot water system.
  • the calorific energy management system is capable of managing the calorific energy transfers by means of a three level control system so as to optimize the energy consumption.
  • At least one heat exchanger is arranged in connection with the exhaust air duct.
  • a heat exchanger can, for example, be a cross-flow or counter-flow heat exchanger (also called plate heat exchangers), and can be used for reducing the total energy consumption of the system by recovering a portion of the heat energy from the exhaust air before it is discharged into the outdoor air.
  • a heat exchanger in connection with the exhaust air duct transfers heat energy from the exhaust air flowing out to the outdoor air flowing in.
  • frost or ice may form on the heat exchanger, which then has to go through a defrost cycle, during which the heat exchanger is heated to melt the ice.
  • a disadvantage of such a defrost cycle is that it takes long time in the previously known systems and thus reduces the effective time during which the heat exchanger can be used for its normal purpose, that is to say heat recovery, which results in an undesirably high energy consumption.
  • This first object is achieved by means of a system according to claim 1 for heating supply air, with simultaneous defrosting of a water-exhaust air heat exchanger, when controlling the indoor climate in a building, which at least comprises
  • first air duct having first input means for introducing outdoor air into the system and first output means for discharging outdoor air treated in the system as supply air into the interior of the building,
  • a second air duct having second input means for introducing exhaust air from the interior of the building into the system and second output means for discharging exhaust air treated in the system into the outdoor air outside the building,
  • an exhaust-supply air heat exchanger which is arranged in connection with said first and second air ducts for selective transfer of heat from said exhaust air being treated in the system to said outdoor air being treated in the system or from said outdoor air being treated in the system to said exhaust air being treated in the system,
  • a water-supply air heat exchanger which is arranged in connection with said first air duct for selective connection to said hot water circuit or said cold water circuit for transfer of heat from said hot water circuit to said outdoor air being treated in the system or from said outdoor being treated in the system to said cold water circuit
  • said water-exhaust air heat exchanger which is arranged in connection with said second air duct for selective connection to said hot water circuit or said cold water circuit for transfer of heat from said hot water circuit to said exhaust air being treated in the system or from said exhaust air being treated in the system to said cold water circuit
  • a heat pump which is arranged in connection with said water system for selective transfer of heat from the hot water circuit to the cold water circuit or from the cold water circuit to the hot water circuit,
  • exhaust-supply air heat exchanger is designed as a rotary heat exchanger, wherein the rotary heat exchanger, with respect to the flow direction in the second air duct, is positioned upstream of the water-exhaust air heat exchanger, and
  • the rotary heat exchanger has an efficiency correlating to rotational speed and is provided with rotational speed control means for enabling defrosting of the water-exhaust air heat exchanger by means of a reduction of said rotational speed in order to obtain an elevated temperature of the exhaust air passing through the water-exhaust air heat exchanger in combination with the hot water circuit simultaneously being connected to the water-exhaust air heat exchanger,
  • the rotational speed control means comprise an electric drive motor for driving the rotation of the rotary heat exchanger, wherein the electric drive motor is adapted to be capable of being controlled to a normal rotational speed during normal operation, in order to provide the highest possible heat transfer capacity of the rotary heat exchanger, and to be capable of being controlled to said reduced rotational speed during a defrost cycle, in order to provide the lowest possible heat transfer capacity of the rotary heat exchanger that is appropriate taking into account other prevailing system conditions at the moment, and thereby the highest possible temperature of the exhaust air passing through the water-exhaust air heat exchanger,
  • hot water circuit provides hot water for use in the water- supply air heat exchanger in said heating of supply air and in the water-exhaust air heat exchanger in the defrosting thereof.
  • the design according to the invention provides a very energy efficient system, at the same time as the cold water and hot water circuits of the water system provide respective reservoirs of cold and hot water, which are always available for use in the system's water-supply air heat exchanger and water-exhaust air heat exchanger, respectively, for use in heating and cooling batteries in the system 's local comfort modules, for storage of heating and cooling energy, respectively, for use in the heat pum p on the hot and the cold side, respectively, and/or for use as hot a nd cold ta p water, respectively, in the build ing, if desired .
  • tem pora ry fluctuations in the demand for cooling, heating and ventilation can be com pensated for, so that the system according to the invention, together with the local comfort modules, can continue to control the local indoor climate toward desired target values independently of whether the system is operated in a heating mode, a cooling mode and/or a defrosting mode.
  • Fig . 1 schematically illustrates the functional principle of a system for controlling the indoor climate in a building, wherein the system is shown in an operating mode for heating the supply a ir with sim ultaneous heat recovery from the exhaust a ir;
  • Fig . 2 schematically illustrates the system of Fig . 1 in an operating mode for cooling the supply air with sim ulta neous transfer of heat to the exha ust air;
  • Fig . 3 schematically illustrates a system according to a preferred embodiment of the invention in an operating mode for heating the supply air with sim ultaneous defrosting of a water-exha ust air heat exchanger arranged in connection with the exhaust a ir d uct;
  • Fig . 4 shows a schematic flow diag ram of a water system in the system according to the invention, with a simplified, serial flow config uration which is suitable for applications where no hot and cold tap water is needed ;
  • Fig. 5 shows a schematic flow diagram of a water system in the system according to the invention, with a parallel flow configuration which is suitable for applications where hot and cold tap water is needed;
  • Fig. 6 schematically illustrates the modular configuration of an indoor system according to a first advantageous embodiment of the invention.
  • Fig. 7 schematically illustrates the modular configuration of a roof-mounted system according to a second advantageous embodiment of the invention.
  • Figures 1-3 schematically illustrate the functional principle of a system for controlling the indoor climate in a building, wherein Fig. 1 shows the system 101 in an operating mode for heating the supply air with simultaneous heat recovery from the exhaust air, Fig. 2 shows the system in an operating mode for cooling the supply air with simultaneous transfer of heat to the exhaust air, and Fig. 3 shows the system according a preferred embodiment of the invention, in an operating mode for heating the supply air with simultaneous defrosting of a water-exhaust air heat exchanger arranged in connection with the exhaust air duct.
  • the system 101 comprises a first air duct 102 having first input means 103 for introducing outdoor air Al into the system and first output means 104, 104' for discharging outdoor air A2 treated in the system as supply air into the interior of the building.
  • the first input means 103 are constituted by an intake opening for outdoor air which, although it is not shown in the figures, can be provided with a grate and/or an air filter and/or an input fan for supply air.
  • the first output means are constituted by an output fan 104 for supply air, and also a discharge opening 104' for supply air which, although it is not shown in the figures, can be provided with a grate, a filter and/or be connected to a supply air conduit for transport of the supply air further on to local supply air means or comfort modules inside the building.
  • the system 101 according to the invention further comprises a second air duct 105 having second input means 106 for introducing exhaust air A3 from the interior of the building into the system and second output means 107, 107', 107" for discharging exhaust air A4 treated in the system into the outdoor air outside the building.
  • the second input means are constituted by an intake opening 106 for exhaust air which, although it is not shown in the figures, also can be connected to an exhaust air conduit for transport of air from local exhaust air means or climate modules inside the building.
  • the second output means are constituted by two output fans 107, 107' for exhaust air, and also by a discharge opening 107" for exhaust air.
  • the system 101 furthermore comprises an exhaust- supply air heat exchanger 108, which is arranged in connection with said first 102 and second 105 air ducts for selective transfer of heat from said exhaust air A3 being treated in the system to said outdoor air Al being treated in the system or from said outdoor air Al being treated in the system to said exhaust air A3 being treated in the system.
  • an exhaust- supply air heat exchanger 108 which is arranged in connection with said first 102 and second 105 air ducts for selective transfer of heat from said exhaust air A3 being treated in the system to said outdoor air Al being treated in the system or from said outdoor air Al being treated in the system to said exhaust air A3 being treated in the system.
  • the system 101 furthermore comprises a water system 109 having a hot water circuit 110 and a cold water circuit 111, a water-supply air heat exchanger 112, which is arranged in connection with said first air duct 102 for selective connection to said hot water circuit 110 or said cold water circuit 111 for transfer of heat from said hot water circuit 110 to said outdoor air Al being treated in the system or from said outdoor air Al being treated in the system to said cold water circuit 111, a water-exhaust air heat exchanger 113, which is arranged in connection with said second air duct 105 for selective connection to said hot water circuit 110 or said cold water circuit 111 for transfer of heat from said hot water circuit 111 to said exhaust air A3 being treated in the system or from said exhaust air A3 being treated in the system to said cold water circuit 111, and a heat pump 114, which is arranged in connection with said water system 109 for selective transfer of heat from the hot water circuit 110 to the cold water circuit 111 or from the cold water circuit 111 to the hot water circuit 110.
  • the exhaust-supply air heat exchanger is designed as a rotary heat exchanger 108.
  • Such rotary heat exchangers are used for energy recovery from exhaust air in some present ventilation systems.
  • a rotary heat exchanger is based around a rotary wheel (a rotor) which usually consists of corrugated aluminium profiles. A portion of the rotary wheel being inside the exhaust air duct is heated by exhaust air flowing therethrough, whereupon the heated portion is gradually rotated further into the supply air duct to emit heat to supply air flowing therethrough.
  • the rotary heat exchanger 108 with respect to the flow direction F in the second air duct 105, is positioned upstream of the water-exhaust air heat exchanger 113.
  • the rotary heat exchanger 108 has an efficiency correlating to rotational speed R and is provided with rotational speed control means for enabling efficient defrosting of the water-exhaust air heat exchanger 113, as is shown in Fig. 3, by means of a reduction of said rotational speed R RE D in order to obtain an elevated temperature of the exhaust air A6 passing through the water- exhaust air heat exchanger 113 in combination with the hot water circuit 110 simultaneously being connected to the water-exhaust air heat exchanger 113.
  • the rotational speed control means comprise an electric drive motor (not shown in the figures) for driving the rotation of the rotary heat exchanger 108, wherein the electric drive motor is adapted to be capable of being controlled to a normal rotational speed R during normal operation (Figs. 1 and 2), in order to provide the highest possible heat transfer capacity of the rotary heat exchanger, and to be capable of being controlled to said reduced rotational speed (RRED) during a defrost cycle (Fig. 3), in order to provide the lowest possible heat transfer capacity of the rotary heat exchanger 108 that is appropriate taking into account other prevailing system conditions at the moment, and thereby the highest possible temperature of the exhaust air A6 passing through the water-exhaust air heat exchanger 113.
  • the rotational speed control means are adapted to be capable of bringing the reduced rotational speed R RE D of the rotary heat exchanger 108 to close to 0 during the defrost cycle.
  • the system 101 comprises a pressure drop meter (not shown in the figures), which is adapted for measuring the pressure drop during the passage of the exhaust air through the water-exhaust air heat exchanger 113 in order to detect an eventual need of defrosting.
  • the pressure drop meter comprises one or several transmitters or sensors for measuring the pressure drop, via air pressure, air velocities and/or air flows, on the exhaust air flow.
  • the transmitters or sensors can be of one of the types electronic pressure transmitter, pitot tube, thermo-anemometer or fan-wheel anemometer, or of any other suitable type.
  • the pressure drop meter can be adapted to be capable of emitting an output signal for initiating a defrost cycle and/or an output signal for controlling the rotational speed control means during such a defrost cycle.
  • the water-supply air heat exchanger 112 and/or the water-exhaust air heat exchanger 113 are designed as a combined heating and cooling battery for transfer of heat to/from said air Al, A3 from/to said water circuits 110, 111.
  • the water-supply air heat exchanger 112 and/or the water-exhaust air heat exchanger 113 are designed for indirect transfer of heat between said air Al, A3 and the water circuits 110, 111 via an intermediate circuit with anti-freeze fluid solution.
  • the heat pump 114 is adapted for direct transfer of heat between the water circuits 110, 111.
  • the heat pump is instead adapted for indirect transfer of heat between the water circuits via an intermediate circuit.
  • the system 101 comprises a control unit 115, which is adapted for controlling the flows of air in the system by means of the input and output means 103, 104, 104', 106, 107, 107', 107", and the flows of fluid in the system by means of a flow control unit M4.
  • Fig. 4 shows a water system with a simplified, serial flow configuration which is suitable for applications where no hot and cold tap water is needed
  • Fig. 5 shows a water system with a parallel flow configuration which is suitable for applications where hot and cold tap water is needed.
  • Fig. 4 shows a water system with a simplified, serial flow configuration which is suitable for
  • the water system 209 thus comprises a hot water tank 210 and a cold water tank 211, wherein both tanks are connected in series on a feed line 216.
  • the water system 309 instead comprises a hot water tank 310 and a cold water tank 311, wherein the cold water tank 311 is connected in series with a feed line 316 and the hot water tank 310 is connected in parallel with the other functional units 319, 317, 312, 313, 318 of the water system, i.e. hot water heater 319, comfort heater 317, water-supply air heat exchanger 312, water- exhaust air heat exchanger 313 and comfort cooler 318.
  • This embodiment ensures that the water system can always provide hot and cold tap water of desired, stable temperatures, and furthermore enables a very high COP of the heat pump module.
  • an air handling module Ml comprising said rotary exhaust-supply air heat exchanger and being controlled by said control unit 415; 515;
  • an air heating and cooling module M2 comprising said water-supply air heat exchanger
  • an energy recovery module M3 comprising said water-exhaust air heat exchanger and being controlled by said control unit 415; 515;
  • a heat pump module M5 comprising said heat pump 414; 514 and being controlled by said control unit 415; 515;
  • said hot water tank 410; 510, said cold water tank 411; 511, said air heating and cooling module M2, said energy recovery module M3, and said at least one local comfort module for water carried heating M6 and/or cooling M7 of supply air are all designed for connection to said fluid flow control module M4, and wherein each of the majority of said functional modules 410; 510, 411; 511, Ml, M2, M3, M4, M5, M6, M7 constitutes a pre-assembled and pretested subsystem provided with quick coupling means 420; 520 for connecting the subsystems into an integrated system 401; 501, which enables control of the indoor climate in said building using at least one control system 415; 515 interacting with and controlling the different subsystems.
  • the modular configuration and the quick coupling means gives the system according to the invention many advantages, such as easier transport, installation, interconnection and start-up.
  • the system according to the invention has a compact configuration and can be installed by a single system installer.
  • the use of single, overall control system minimizes the risk that different subsystems get into conflicts with each other, but embodiments of the invention comprising several separate subsystems interacting with each other, or in which the control system has a distributed topology and comprises a plurality of interconnected processor boards with individual calculation algorithms, are also conceivable.
  • the system's heat pump module can be utilized as an exhaust air heat pump when there is a demand for ventilation or as an outdoor air heat pump when there is no demand for ventilation.
  • the different functional modules can be connected into the system in ways different from what is seen in the figures, for example such that the module M6 is connected in a parallel flow configuration instead of in a serial configuration.
  • Figure 1 shows the system in an operating mode for heating supply air with simultaneous heat recovery from exhaust air.
  • cold outdoor air Al with a temperature of -15 °C can be introduced into the system 101.
  • the temperature of the treated outdoor air A5 is increased to +13 °C.
  • the temperature of the treated outdoor air is increased to 20 °C and it can be introduced as supply air A2 into the interior of the building, either directly by means of a suitable supply air means or via an air conduit to a local comfort module.
  • FIG. 2 shows the system in an operating mode for cooling supply air with simultaneous transfer of heat to exhaust air.
  • warm outdoor air Al with a temperature of +26 °C can be introduced into the system 101.
  • the temperature of the treated outdoor air A5 is reduced to +24 °C.
  • the temperature of the treated outdoor air is reduced to 16 °C and it can be introduced as supply air A2 into the interior of the building, either directly by means of a suitable supply air means or via an air conduit to a local comfort module.
  • Warm exhaust air A3 from the interior of the building, with a temperature of +23 °C, is introduced into the system 101.
  • the temperature of the treated exhaust air A6 is increased to +25 °C.
  • the temperature of the treated exhaust air A4 is increased to +30 °C and it can be discharged into the outdoor air outside the building.
  • FIG 3 shows the system according to the invention in an operating mode for heating supply air with simultaneous defrosting of the water-exhaust air heat exchanger 113.
  • this operating mode for example, cold outdoor air Al with a temperature of -15 °C can be introduced into the system 101.
  • the rotary heat exchanger 108 is operated at a reduced rotational speed RRED, for example a rotational speed corresponding to a reduction of the efficiency of the rotary heat exchanger to 50 % of the efficiency at normal rotational speed R (Figs. 1 and 2).
  • RRED reduced rotational speed corresponding to a reduction of the efficiency of the rotary heat exchanger to 50 % of the efficiency at normal rotational speed R (Figs. 1 and 2).
  • the temperature of the treated outdoor air is increased to 20 °C and it can be introduced as supply air A2 into the interior of the building, either directly by means of a suitable supply air means or via an air conduit to a local comfort module.
  • Warm exhaust air A3 from the interior of the building, with a temperature of +22 °C, is introduced into the system 101.
  • the temperature of the treated exhaust air A6 is reduced to +8 °C.
  • the temperature of the treated exhaust air A4 is reduced to +4 °C and it can be discharged into the outdoor air outside the building.
  • the reduced rotational speed R RE D of the rotary heat exchanger in the defrosting mode results in an elevated temperature of the exhaust air A6 passing through the water-exhaust air heat exchanger 113.
  • a considerably elevated temperature of the metal surfaces which are to be defrosted, and a very short defrost cycle in comparison to previously known systems, are obtained.
  • the local temperature increase obtained in the water-exhaust air heat exchanger 113 in the defrosting mode is of the order of 20 °C in the described example, this in comparison to when the system is operated in the previously described heating mode according to Fig. 1.
  • Heating of radiators or floor heating system Alternative 12 (serial flow configuration according to Fig. 4)

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Abstract

A system (101) for heating supply air, with simultaneous defrosting of a water-exhaust air heat exchanger, when controlling the indoor climate in a building, at least comprising a first air duct (102) for supply air, a second air duct (105) for exhaust air, an exhaust-supply air heat exchanger (108) for selective heat transfer between supply air and exhaust air, a water system (109) having a hot water circuit (110) and a cold water circuit (111), a water-supply air heat exchanger (112) at the first air duct (102) and the water-exhaust air heat exchanger (113) at the second air duct (105), both for selective connection to the hot water circuit (110) or the cold water circuit (111), a heat pump (114) for selective heat transfer between the water circuits (110, 111), wherein the exhaust-supply air heat exchanger is a rotary heat exchanger (108)positioned upstream of the water-exhaust air heat exchanger (113) and having an efficiency correlating to rotational speed and rotational speed control means for enabling efficient defrosting of the water-exhaust air heat exchanger (113) by reduction of the rotational speed (RRED) in order to obtain an elevated temperature of the exhaust air (A6) passing through the water-exhaust air heat exchanger (113) in combination with the hot water circuit (110) simultaneously being connected to the water-exhaust air heat exchanger (113).

Description

A system for heating supply air with simultaneous defrosting of a water-exhaust air heat exchanger
TECHNICAL FIELD
The present invention relates to a system for heating supply air, with simultaneous defrosting of a water-exhaust air heat exchanger, when controlling the indoor climate in a building.
BACKGROUND OF THE INVENTION
In offices and other larger premises, there is often a need to be able to control the indoor climate separately in different parts of the premises or in individual rooms. An accurate local temperature and ventilation control is required to ensure a sufficient comfort level for the persons present in a building. Also heat generated by electric appliances and heat and exhaled air generated by persons inside the building have to be taken into account for the control. Together with the prevailing weather conditions, these factors have a large influence on the instantaneous demand for heating, cooling and ventilation capacity.
Different systems for controlling the indoor climate in buildings are known previously. For instance, US2004/0148950 Al discloses an air-conditioning system for a building that comprises a hot water circuit, a cold water circuit and several local air conditioning units. Each of the local air conditioning units comprises a fan for blowing air into a space in the building, a heating coil connected to the hot water circuit and/or a cooling coil connected to the cold water circuit. At least one temperature control system allows control of the heating power of the heating coils and the cooling power of the cooling coils. A calorific energy management system is provided with a heat pump for transferring calorific energy from the cold water system to the hot water system, from the cold water system to the outdoor air and from the outdoor air to the hot water system. The calorific energy management system is capable of managing the calorific energy transfers by means of a three level control system so as to optimize the energy consumption.
In systems for controlling the indoor climate in buildings, it is common that at least one heat exchanger is arranged in connection with the exhaust air duct. Such a heat exchanger can, for example, be a cross-flow or counter-flow heat exchanger (also called plate heat exchangers), and can be used for reducing the total energy consumption of the system by recovering a portion of the heat energy from the exhaust air before it is discharged into the outdoor air. Thus, such a heat exchanger in connection with the exhaust air duct transfers heat energy from the exhaust air flowing out to the outdoor air flowing in. In certain conditions, frost or ice may form on the heat exchanger, which then has to go through a defrost cycle, during which the heat exchanger is heated to melt the ice. A disadvantage of such a defrost cycle is that it takes long time in the previously known systems and thus reduces the effective time during which the heat exchanger can be used for its normal purpose, that is to say heat recovery, which results in an undesirably high energy consumption. SUMMARY OF THE INVENTION
It is therefore a first object of the invention to provide a more energy efficient system for controlling the indoor climate in a building, by designing the system such that the time that a heat exchanger arranged in connection with the exhaust air duct has to be operated in a defrost cycle can be minimized and the time for energy recovery from the exhaust air thereby can be maximized.
This first object is achieved by means of a system according to claim 1 for heating supply air, with simultaneous defrosting of a water-exhaust air heat exchanger, when controlling the indoor climate in a building, which at least comprises
- a first air duct having first input means for introducing outdoor air into the system and first output means for discharging outdoor air treated in the system as supply air into the interior of the building,
- a second air duct having second input means for introducing exhaust air from the interior of the building into the system and second output means for discharging exhaust air treated in the system into the outdoor air outside the building,
- an exhaust-supply air heat exchanger, which is arranged in connection with said first and second air ducts for selective transfer of heat from said exhaust air being treated in the system to said outdoor air being treated in the system or from said outdoor air being treated in the system to said exhaust air being treated in the system,
- a water system having a hot water circuit and a cold water circuit,
- a water-supply air heat exchanger, which is arranged in connection with said first air duct for selective connection to said hot water circuit or said cold water circuit for transfer of heat from said hot water circuit to said outdoor air being treated in the system or from said outdoor being treated in the system to said cold water circuit, - said water-exhaust air heat exchanger, which is arranged in connection with said second air duct for selective connection to said hot water circuit or said cold water circuit for transfer of heat from said hot water circuit to said exhaust air being treated in the system or from said exhaust air being treated in the system to said cold water circuit,
- a heat pump, which is arranged in connection with said water system for selective transfer of heat from the hot water circuit to the cold water circuit or from the cold water circuit to the hot water circuit,
wherein the exhaust-supply air heat exchanger is designed as a rotary heat exchanger, wherein the rotary heat exchanger, with respect to the flow direction in the second air duct, is positioned upstream of the water-exhaust air heat exchanger, and
wherein the rotary heat exchanger has an efficiency correlating to rotational speed and is provided with rotational speed control means for enabling defrosting of the water-exhaust air heat exchanger by means of a reduction of said rotational speed in order to obtain an elevated temperature of the exhaust air passing through the water-exhaust air heat exchanger in combination with the hot water circuit simultaneously being connected to the water-exhaust air heat exchanger,
and wherein the rotational speed control means comprise an electric drive motor for driving the rotation of the rotary heat exchanger, wherein the electric drive motor is adapted to be capable of being controlled to a normal rotational speed during normal operation, in order to provide the highest possible heat transfer capacity of the rotary heat exchanger, and to be capable of being controlled to said reduced rotational speed during a defrost cycle, in order to provide the lowest possible heat transfer capacity of the rotary heat exchanger that is appropriate taking into account other prevailing system conditions at the moment, and thereby the highest possible temperature of the exhaust air passing through the water-exhaust air heat exchanger,
and wherein the hot water circuit provides hot water for use in the water- supply air heat exchanger in said heating of supply air and in the water-exhaust air heat exchanger in the defrosting thereof.
Owing to the shorter time required for the defrost cycle, the design according to the invention provides a very energy efficient system, at the same time as the cold water and hot water circuits of the water system provide respective reservoirs of cold and hot water, which are always available for use in the system's water-supply air heat exchanger and water-exhaust air heat exchanger, respectively, for use in heating and cooling batteries in the system 's local comfort modules, for storage of heating and cooling energy, respectively, for use in the heat pum p on the hot and the cold side, respectively, and/or for use as hot a nd cold ta p water, respectively, in the build ing, if desired . Owing to the water carried heat storage capacity of the system according to the invention, tem pora ry fluctuations in the demand for cooling, heating and ventilation can be com pensated for, so that the system according to the invention, together with the local comfort modules, can continue to control the local indoor climate toward desired target values independently of whether the system is operated in a heating mode, a cooling mode and/or a defrosting mode.
Other objects, advantages a nd features of the present invention will become apparent from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following, a num ber of em bodiments of the invention will be described more closely, only as exam ples and with reference to the accom pa nying schematic drawings, in which :
Fig . 1 schematically illustrates the functional principle of a system for controlling the indoor climate in a building, wherein the system is shown in an operating mode for heating the supply a ir with sim ultaneous heat recovery from the exhaust a ir;
Fig . 2 schematically illustrates the system of Fig . 1 in an operating mode for cooling the supply air with sim ulta neous transfer of heat to the exha ust air;
Fig . 3 schematically illustrates a system according to a preferred embodiment of the invention in an operating mode for heating the supply air with sim ultaneous defrosting of a water-exha ust air heat exchanger arranged in connection with the exhaust a ir d uct;
Fig . 4 shows a schematic flow diag ram of a water system in the system according to the invention, with a simplified, serial flow config uration which is suitable for applications where no hot and cold tap water is needed ; Fig. 5 shows a schematic flow diagram of a water system in the system according to the invention, with a parallel flow configuration which is suitable for applications where hot and cold tap water is needed; Fig. 6 schematically illustrates the modular configuration of an indoor system according to a first advantageous embodiment of the invention; and
Fig. 7 schematically illustrates the modular configuration of a roof-mounted system according to a second advantageous embodiment of the invention.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
Figures 1-3 schematically illustrate the functional principle of a system for controlling the indoor climate in a building, wherein Fig. 1 shows the system 101 in an operating mode for heating the supply air with simultaneous heat recovery from the exhaust air, Fig. 2 shows the system in an operating mode for cooling the supply air with simultaneous transfer of heat to the exhaust air, and Fig. 3 shows the system according a preferred embodiment of the invention, in an operating mode for heating the supply air with simultaneous defrosting of a water-exhaust air heat exchanger arranged in connection with the exhaust air duct.
The system 101 according to the invention comprises a first air duct 102 having first input means 103 for introducing outdoor air Al into the system and first output means 104, 104' for discharging outdoor air A2 treated in the system as supply air into the interior of the building. In the shown embodiment, the first input means 103 are constituted by an intake opening for outdoor air which, although it is not shown in the figures, can be provided with a grate and/or an air filter and/or an input fan for supply air. In the shown embodiment, the first output means are constituted by an output fan 104 for supply air, and also a discharge opening 104' for supply air which, although it is not shown in the figures, can be provided with a grate, a filter and/or be connected to a supply air conduit for transport of the supply air further on to local supply air means or comfort modules inside the building. The system 101 according to the invention further comprises a second air duct 105 having second input means 106 for introducing exhaust air A3 from the interior of the building into the system and second output means 107, 107', 107" for discharging exhaust air A4 treated in the system into the outdoor air outside the building. In the shown embodiment, the second input means are constituted by an intake opening 106 for exhaust air which, although it is not shown in the figures, also can be connected to an exhaust air conduit for transport of air from local exhaust air means or climate modules inside the building. In the shown embodiment, the second output means are constituted by two output fans 107, 107' for exhaust air, and also by a discharge opening 107" for exhaust air.
The system 101 according to the invention furthermore comprises an exhaust- supply air heat exchanger 108, which is arranged in connection with said first 102 and second 105 air ducts for selective transfer of heat from said exhaust air A3 being treated in the system to said outdoor air Al being treated in the system or from said outdoor air Al being treated in the system to said exhaust air A3 being treated in the system.
The system 101 according to the invention furthermore comprises a water system 109 having a hot water circuit 110 and a cold water circuit 111, a water-supply air heat exchanger 112, which is arranged in connection with said first air duct 102 for selective connection to said hot water circuit 110 or said cold water circuit 111 for transfer of heat from said hot water circuit 110 to said outdoor air Al being treated in the system or from said outdoor air Al being treated in the system to said cold water circuit 111, a water-exhaust air heat exchanger 113, which is arranged in connection with said second air duct 105 for selective connection to said hot water circuit 110 or said cold water circuit 111 for transfer of heat from said hot water circuit 111 to said exhaust air A3 being treated in the system or from said exhaust air A3 being treated in the system to said cold water circuit 111, and a heat pump 114, which is arranged in connection with said water system 109 for selective transfer of heat from the hot water circuit 110 to the cold water circuit 111 or from the cold water circuit 111 to the hot water circuit 110.
It is characteristic of the system 101 according to the invention that the exhaust-supply air heat exchanger is designed as a rotary heat exchanger 108. Such rotary heat exchangers are used for energy recovery from exhaust air in some present ventilation systems. A rotary heat exchanger is based around a rotary wheel (a rotor) which usually consists of corrugated aluminium profiles. A portion of the rotary wheel being inside the exhaust air duct is heated by exhaust air flowing therethrough, whereupon the heated portion is gradually rotated further into the supply air duct to emit heat to supply air flowing therethrough.
It is also characteristic of the system 101 according to the invention that the rotary heat exchanger 108, with respect to the flow direction F in the second air duct 105, is positioned upstream of the water-exhaust air heat exchanger 113.
Furthermore, it is characteristic of the system 101 according to the invention that the rotary heat exchanger 108 has an efficiency correlating to rotational speed R and is provided with rotational speed control means for enabling efficient defrosting of the water-exhaust air heat exchanger 113, as is shown in Fig. 3, by means of a reduction of said rotational speed RRED in order to obtain an elevated temperature of the exhaust air A6 passing through the water- exhaust air heat exchanger 113 in combination with the hot water circuit 110 simultaneously being connected to the water-exhaust air heat exchanger 113.
In the system 101 according to the invention, the rotational speed control means comprise an electric drive motor (not shown in the figures) for driving the rotation of the rotary heat exchanger 108, wherein the electric drive motor is adapted to be capable of being controlled to a normal rotational speed R during normal operation (Figs. 1 and 2), in order to provide the highest possible heat transfer capacity of the rotary heat exchanger, and to be capable of being controlled to said reduced rotational speed (RRED) during a defrost cycle (Fig. 3), in order to provide the lowest possible heat transfer capacity of the rotary heat exchanger 108 that is appropriate taking into account other prevailing system conditions at the moment, and thereby the highest possible temperature of the exhaust air A6 passing through the water-exhaust air heat exchanger 113. In one advantageous embodiment, the rotational speed control means are adapted to be capable of bringing the reduced rotational speed RRED of the rotary heat exchanger 108 to close to 0 during the defrost cycle.
In one advantageous embodiment, the system 101 comprises a pressure drop meter (not shown in the figures), which is adapted for measuring the pressure drop during the passage of the exhaust air through the water-exhaust air heat exchanger 113 in order to detect an eventual need of defrosting. The pressure drop meter comprises one or several transmitters or sensors for measuring the pressure drop, via air pressure, air velocities and/or air flows, on the exhaust air flow. The transmitters or sensors can be of one of the types electronic pressure transmitter, pitot tube, thermo-anemometer or fan-wheel anemometer, or of any other suitable type. Advantageously, the pressure drop meter can be adapted to be capable of emitting an output signal for initiating a defrost cycle and/or an output signal for controlling the rotational speed control means during such a defrost cycle.
In the preferred embodiment of the system 101 according to the invention, the water-supply air heat exchanger 112 and/or the water-exhaust air heat exchanger 113 are designed as a combined heating and cooling battery for transfer of heat to/from said air Al, A3 from/to said water circuits 110, 111.
In one advantageous embodiment of the system according to the invention (not shown in detail in the figures), the water-supply air heat exchanger 112 and/or the water-exhaust air heat exchanger 113 are designed for indirect transfer of heat between said air Al, A3 and the water circuits 110, 111 via an intermediate circuit with anti-freeze fluid solution.
In a first alternative embodiment of the system 101 according to the invention, the heat pump 114 is adapted for direct transfer of heat between the water circuits 110, 111. In a second alternative embodiment, the heat pump is instead adapted for indirect transfer of heat between the water circuits via an intermediate circuit.
In one advantageous embodiment, the system 101 according to the invention comprises a control unit 115, which is adapted for controlling the flows of air in the system by means of the input and output means 103, 104, 104', 106, 107, 107', 107", and the flows of fluid in the system by means of a flow control unit M4. Figures 4 and 5, respectively, schematically show two alternative flow configurations of the water system included in the system according to the invention, wherein Fig. 4 shows a water system with a simplified, serial flow configuration which is suitable for applications where no hot and cold tap water is needed, whereas Fig. 5 shows a water system with a parallel flow configuration which is suitable for applications where hot and cold tap water is needed. In one embodiment of the system according to the invention (Fig. 4), the water system 209 thus comprises a hot water tank 210 and a cold water tank 211, wherein both tanks are connected in series on a feed line 216. In an alternative embodiment of the system according to the invention (Fig. 5), the water system 309 instead comprises a hot water tank 310 and a cold water tank 311, wherein the cold water tank 311 is connected in series with a feed line 316 and the hot water tank 310 is connected in parallel with the other functional units 319, 317, 312, 313, 318 of the water system, i.e. hot water heater 319, comfort heater 317, water-supply air heat exchanger 312, water- exhaust air heat exchanger 313 and comfort cooler 318. This embodiment ensures that the water system can always provide hot and cold tap water of desired, stable temperatures, and furthermore enables a very high COP of the heat pump module.
Figures 6 and 7, respectively, schematically illustrate the advantageous modular configuration of an indoor system and of a roof-mounted system, respectively, according to the invention. It is common to the two different system designs that the system 401; 501 comprises at least the following functional modules:
- a hot water tank 410; 510;
- a cold water tank 411; 511;
- a control unit 415; 515;
- an air handling module Ml comprising said rotary exhaust-supply air heat exchanger and being controlled by said control unit 415; 515;
- an air heating and cooling module M2 comprising said water-supply air heat exchanger;
- an energy recovery module M3 comprising said water-exhaust air heat exchanger and being controlled by said control unit 415; 515;
- a fluid flow control module M4 being controlled by said control unit 415; 515;
- a heat pump module M5 comprising said heat pump 414; 514 and being controlled by said control unit 415; 515;
- at least one local comfort module for water carried heating M6 and/or cooling M7 of supply air,
wherein said hot water tank 410; 510, said cold water tank 411; 511, said air heating and cooling module M2, said energy recovery module M3, and said at least one local comfort module for water carried heating M6 and/or cooling M7 of supply air are all designed for connection to said fluid flow control module M4, and wherein each of the majority of said functional modules 410; 510, 411; 511, Ml, M2, M3, M4, M5, M6, M7 constitutes a pre-assembled and pretested subsystem provided with quick coupling means 420; 520 for connecting the subsystems into an integrated system 401; 501, which enables control of the indoor climate in said building using at least one control system 415; 515 interacting with and controlling the different subsystems.
When the reference numerals M1-M7 corresponding to the different functional modules are concerned, these have, when possible, also been inserted into the previously described Figures 1-5. The modular configuration and the quick coupling means gives the system according to the invention many advantages, such as easier transport, installation, interconnection and start-up. The system according to the invention has a compact configuration and can be installed by a single system installer. The use of single, overall control system minimizes the risk that different subsystems get into conflicts with each other, but embodiments of the invention comprising several separate subsystems interacting with each other, or in which the control system has a distributed topology and comprises a plurality of interconnected processor boards with individual calculation algorithms, are also conceivable. The system's heat pump module can be utilized as an exhaust air heat pump when there is a demand for ventilation or as an outdoor air heat pump when there is no demand for ventilation. Furthermore, it should be noted that the different functional modules can be connected into the system in ways different from what is seen in the figures, for example such that the module M6 is connected in a parallel flow configuration instead of in a serial configuration.
PRIMARY OPERATING MODES
In the following, brief descriptions of three primary operating modes of the system will follow, with reference to Figures 1, 2 and 3, respectively. When the reference numerals W1-W6 are concerned, these indicate different water flows starting from the fluid flow control module M4 of the water system, wherein Wl refers to input flow to the water-supply air heat exchanger 112, W2 to input flow to the water-exhaust air heat exchanger 113, W3 to input flow to a local comfort module for water carried heating of supply air, W4 to input flow to a local comfort module for water carried cooling of supply air, W5 to input flow to radiators, and W6 to input flow to hot water production. Heating mode
Figure 1 shows the system in an operating mode for heating supply air with simultaneous heat recovery from exhaust air. In this operating mode, for example, cold outdoor air Al with a temperature of -15 °C can be introduced into the system 101. After passage through the rotary heat exchanger 108 and heat exchange with warmer exhaust air A3, the temperature of the treated outdoor air A5 is increased to +13 °C. After passage past the water-supply air heat exchanger 112 and heat exchange with the hot water circuit Wl, the temperature of the treated outdoor air is increased to 20 °C and it can be introduced as supply air A2 into the interior of the building, either directly by means of a suitable supply air means or via an air conduit to a local comfort module. Warm exhaust air A3 from the interior of the building, with a temperature of +22 °C, is introduced into the system 101. After passage through the rotary heat exchanger 108 and heat exchange with the cold outdoor air Al flowing in, the temperature of the treated exhaust air A6 is reduced to -6 °C. After passage past the water-exhaust air heat exchanger 113 and heat exchange with the cold water circuit W2, the temperature of the treated exhaust air A4 is reduced to -16 °C and it can be discharged into the outdoor air outside the building.
Cooling mode
Figure 2 shows the system in an operating mode for cooling supply air with simultaneous transfer of heat to exhaust air. In this operating mode, for example, warm outdoor air Al with a temperature of +26 °C can be introduced into the system 101. After passage through the rotary heat exchanger 108 and heat exchange with colder exhaust air A3, the temperature of the treated outdoor air A5 is reduced to +24 °C. After passage past the water-supply air heat exchanger 112 and heat exchange with the cold water circuit Wl, the temperature of the treated outdoor air is reduced to 16 °C and it can be introduced as supply air A2 into the interior of the building, either directly by means of a suitable supply air means or via an air conduit to a local comfort module. Warm exhaust air A3 from the interior of the building, with a temperature of +23 °C, is introduced into the system 101. After passage through the rotary heat exchanger 108 and heat exchange with the warmer outdoor air Al flowing in, the temperature of the treated exhaust air A6 is increased to +25 °C. After passage past the water-exhaust air heat exchanger 113 and heat exchange with the hot water circuit W2, the temperature of the treated exhaust air A4 is increased to +30 °C and it can be discharged into the outdoor air outside the building.
Defrosting mode
Figure 3 shows the system according to the invention in an operating mode for heating supply air with simultaneous defrosting of the water-exhaust air heat exchanger 113. In this operating mode, for example, cold outdoor air Al with a temperature of -15 °C can be introduced into the system 101. In this operating mode, the rotary heat exchanger 108 is operated at a reduced rotational speed RRED, for example a rotational speed corresponding to a reduction of the efficiency of the rotary heat exchanger to 50 % of the efficiency at normal rotational speed R (Figs. 1 and 2). After passage through the rotary heat exchanger 108 running at reduced rotational speed RRED and heat exchange with warmer exhaust air A3, the temperature of the treated outdoor air A5 is increased to 0 °C. After passage past the water-supply air heat exchanger 112 and heat exchange with the hot water circuit Wl, the temperature of the treated outdoor air is increased to 20 °C and it can be introduced as supply air A2 into the interior of the building, either directly by means of a suitable supply air means or via an air conduit to a local comfort module. Warm exhaust air A3 from the interior of the building, with a temperature of +22 °C, is introduced into the system 101. After passage through the rotary heat exchanger 108 running at reduced rotational speed RRED and heat exchange with the cold outdoor air Al flowing in, the temperature of the treated exhaust air A6 is reduced to +8 °C. After passage past the water-exhaust air heat exchanger 113 and heat exchange with the hot water circuit W2, the temperature of the treated exhaust air A4 is reduced to +4 °C and it can be discharged into the outdoor air outside the building. Thus, in comparison to the previously described heating mode according to Fig. 1, the reduced rotational speed RRED of the rotary heat exchanger in the defrosting mode results in an elevated temperature of the exhaust air A6 passing through the water-exhaust air heat exchanger 113. In combination with the hot water circuit Wl simultaneously being connected to the water-exhaust air heat exchanger 113, a considerably elevated temperature of the metal surfaces which are to be defrosted, and a very short defrost cycle in comparison to previously known systems, are obtained. The local temperature increase obtained in the water-exhaust air heat exchanger 113 in the defrosting mode is of the order of 20 °C in the described example, this in comparison to when the system is operated in the previously described heating mode according to Fig. 1. At higher outdoor temperatures, even larger local temperature increases and even shorter defrost cycles are possible, since a larger reduction of the rotational speed and the efficiency of the rotary heat exchanger can be utilized. ALTERNATIVE OPERATING MODES
In order to give a better understanding of the many possibilities offered by the present invention, brief summaries of a number of different operating modes possible with the system according to the invention will follow below. Alternative 1 (serial flow configuration according to Fig. 4)
Heating of supply air and comfort modules
Cooling of exhaust air and comfort modules
Heat pump active or inactive
No defrosting
Alternative 2 (serial flow configuration according to Fig. 4)
Cooling of supply air and comfort modules
Heating of exhaust air and comfort modules
Heat pump active or inactive
Alternative 3 (serial flow configuration according to Fig. 4)
Heating of supply air and comfort modules
Cooling of comfort modules
Heat pump active or inactive
Defrosting
Alternative 4 (parallel flow configuration according to Fig. 5)
Heating of supply air and comfort modules
Cooling of exhaust air and comfort modules
Heat pump active, No charging of tank
No defrosting, No heating of tap water
Alternative 5 (parallel flow configuration according to Fig. 5)
Heating of supply air and comfort modules
Cooling of exhaust air and comfort modules
Heat pump active, Charging of tank
No defrosting, No heating of tap water Alternative 6 (parallel flow configuration according to Fig. 5) Heating of supply air and comfort modules
Cooling of exhaust air and comfort modules
Heat pump active, Discharging of tank
No defrosting, Heating of tap water
Alternative 7 (parallel flow configuration according to Fig. 5) Heating of supply air and comfort modules
Cooling of comfort modules
Heat pump active, No charging of tank
Defrosting, No heating of tap water
Alternative 8 (parallel flow configuration according to Fig. 5) Cooling of supply air and comfort modules
Heating of exhaust air and comfort modules
Heat pump active, No charging of tank
No defrosting, No heating of tap water
Alternative 9 (parallel flow configuration according to Fig. 5) Cooling of supply air and comfort modules
Heating of comfort modules
Heat pump active, Discharging of tank
No defrosting, Heating of tap water Alternative 10 (serial flow configuration according to Fig. 4) One supply duct for air
Cooling of comfort modules, chilled beams
Heating of comfort modules, radiators or floor heating system
Alternative 11 (serial flow configuration according to Fig. 4)
One supply duct for air
Cooling of supply air
Heating of radiators or floor heating system Alternative 12 (serial flow configuration according to Fig. 4)
One or two supply ducts for air
Cooling of supply air
Heating of supply air In the foregoing, a number of embodiments of the invention have been described with reference to the figures in the accompanying drawings. It should be understood that the described embodiments and the details in the figures should only be regarded as examples, and that many other embodiments of the invention are possible within the scope of the following claims.

Claims

1. A system for heating supply air, with simultaneous defrosting of a water- exhaust air heat exchanger, when controlling the indoor climate in a building, wherein the system (101; 401; 501) at least comprises
- a first air duct (102) having first input means (103) for introducing outdoor air (Al) into the system and first output means (104, 104') for discharging outdoor air (A2) treated in the system as supply air into the interior of the building,
- a second air duct (105) having second input means (106) for introducing exhaust air (A3) from the interior of the building into the system and second output means (107, 107', 107") for discharging exhaust air (A4) treated in the system into the outdoor air outside the building,
- an exhaust-supply air heat exchanger (108), which is arranged in connection with said first (102) and second (105) air ducts for selective transfer of heat from said exhaust air (A3) being treated in the system to said outdoor air (Al) being treated in the system or from said outdoor air (Al) being treated in the system to said exhaust air (A3) being treated in the system,
- a water system (109; 209; 309) having a hot water circuit (110) and a cold water circuit (111),
- a water-supply air heat exchanger (112), which is arranged in connection with said first air duct (102) for selective connection to said hot water circuit (110) or said cold water circuit (111) for transfer of heat from said hot water circuit (110) to said outdoor air (Al) being treated in the system or from said outdoor air (Al) being treated in the system to said cold water circuit (111),
- said water-exhaust air heat exchanger (113), which is arranged in connection with said second air duct (105) for selective connection to said hot water circuit (110) or said cold water circuit (111) for transfer of heat from said hot water circuit (111) to said exhaust air (A3) being treated in the system or from said exhaust air (A3) being treated in the system to said cold water circuit (111), - a heat pump (114; 214; 314; 414; 514), which is arranged in connection with said water system (109) for selective transfer of heat from the hot water circuit (110) to the cold water circuit (111) or from the cold water circuit (111) to the hot water circuit (110),
c h a r a c t e r i z e d i n
that the exhaust-supply air heat exchanger is designed as a rotary heat exchanger (108), that the rotary heat exchanger (108), with respect to the flow direction (F) in the second air duct (105), is positioned upstream of the water-exhaust air heat exchanger (113), and
that the rotary heat exchanger (108) has an efficiency correlating to rotational speed (R) and is provided with rotational speed control means for enabling defrosting of the water-exhaust air heat exchanger (113) by means of a reduction of said rotational speed (RRED) in order to obtain an elevated temperature of the exhaust air (A6) passing through the water-exhaust air heat exchanger (113) in combination with the hot water circuit (110) simultaneously being connected to the water-exhaust air heat exchanger (113),
wherein the rotational speed control means comprise an electric drive motor for driving the rotation of the rotary heat exchanger (108), wherein the electric drive motor is adapted to be capable of being controlled to a normal rotational speed (R) during normal operation, in order to provide the highest possible heat transfer capacity of the rotary heat exchanger, and to be capable of being controlled to said reduced rotational speed (RRED) during a defrost cycle, in order to provide the lowest possible heat transfer capacity of the rotary heat exchanger (108) that is appropriate taking into account other prevailing system conditions at the moment, and thereby the highest possible temperature of the exhaust air (A6) passing through the water-exhaust air heat exchanger (113), wherein the hot water circuit provides hot water for use in the water-supply air heat exchanger in said heating of supply air and in the water-exhaust air heat exchanger in the defrosting thereof.
2. The system according to claim 1,
c h a r a c t e r i z e d i n that the rotational speed control means are adapted to be capable of bringing the reduced rotational speed (RRED) of the rotary heat exchanger (108) to close to 0 during the defrost cycle.
3. The system according to any one of the preceding claims,
c h a r a c t e r i z e d i n that the system comprises a pressure drop meter adapted for measuring the pressure drop during the passage of the exhaust air through the water-exhaust air heat exchanger (113) in order to detect an eventual need of defrosting.
4. The system according to any one of the preceding claims,
c h a r a c t e r i z e d i n that said water-supply air heat exchanger (112) and/or said water-exhaust air heat exchanger (113) are designed as a combined heating and cooling battery for transfer of heat to/from said air (Al, A3) from/to said water circuits (110, 111).
5. The system according to any one of the preceding claims,
c h a ra cte ri zed i n that said water-supply air heat exchanger (112) and/or said water-exhaust air heat exchanger (113) are designed for indirect transfer of heat between said air (Al, A3) and said water circuits (110, 111) via an intermediate circuit with anti-freeze fluid solution.
6. The system according to any one of the claims 1-5,
c h a ra cte ri zed i n that said heat pump (114) is adapted for direct transfer of heat between said water circuits (110, 111).
7. The system according to any one of the claims 1-5,
c h a ra cte ri zed i n that said heat pump is adapted for indirect transfer of heat between said water circuits via an intermediate circuit.
8. The system according to any one of the preceding claims,
c h a ra cte ri zed i n that the system comprises a control unit (115), which is adapted for controlling the flows of air in the system by means of said input and output means (103, 104, 104', 106, 107, 107', 107") and the flows of fluid in the system by means of a flow control unit (M4).
9. The system according to any one of the claims 1-8,
c h a ra cte ri zed i n that said water system (209) comprises a hot water tank (210) and a cold water tank (211), wherein both tanks are connected in series on a feed line (216).
10. The system according to any one of the claims 1-8,
c h a ra cte ri zed i n that said water system (309) ) comprises a hot water tank (310) and a cold water tank (311), wherein the cold water tank (311) is connected in series with a feed line (316) and the hot water tank (310) is connected in parallel with the other functional units (319, 317, 312, 313, 318) of the water system.
PCT/SE2012/051289 2011-11-23 2012-11-22 A system for heating supply air with simultaneous defrosting of a water-exhaust air heat exchanger WO2013081532A1 (en)

Priority Applications (1)

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EP12853121.7A EP2783165B1 (en) 2011-11-23 2012-11-22 A system for heating supply air with simultaneous defrosting of a water-exhaust air heat exchanger

Applications Claiming Priority (2)

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SE1151114-4 2011-11-23
SE1151114A SE537199C2 (en) 2011-11-23 2011-11-23 System for controlling the indoor climate in a building

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WO2014098724A1 (en) * 2012-12-21 2014-06-26 Fläkt Woods AB Method and apparatus for defrosting of an evaporator in connection with an air handling unit
EP3472526A4 (en) * 2016-06-16 2020-02-26 FläktGroup Sweden AB Method and device for reducing or eliminating the temperature drop of the supply air temperature during defrosting of an evaporator at an air handling unit

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US11486595B2 (en) 2017-10-17 2022-11-01 Swegon Operations Ab Defrosting cycle control
FI128644B (en) 2018-05-23 2020-09-30 At Air Oy Air treatment equipment, method for operating an air treatment equipment, and method for restoring an air treatment equipment

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US9423164B2 (en) 2012-12-21 2016-08-23 Fläkt Woods AB Method and apparatus for the defrosting of an evaporator in connection with an air handling unit
EP3472526A4 (en) * 2016-06-16 2020-02-26 FläktGroup Sweden AB Method and device for reducing or eliminating the temperature drop of the supply air temperature during defrosting of an evaporator at an air handling unit

Also Published As

Publication number Publication date
EP2783165A4 (en) 2015-11-18
EP2783165B1 (en) 2017-03-15
SE1151114A1 (en) 2013-05-24
SE537199C2 (en) 2015-03-03
EP2783165A1 (en) 2014-10-01

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