WO2011110946A2 - Circuit d'échange de chaleur - Google Patents

Circuit d'échange de chaleur Download PDF

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Publication number
WO2011110946A2
WO2011110946A2 PCT/IB2011/000616 IB2011000616W WO2011110946A2 WO 2011110946 A2 WO2011110946 A2 WO 2011110946A2 IB 2011000616 W IB2011000616 W IB 2011000616W WO 2011110946 A2 WO2011110946 A2 WO 2011110946A2
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WO
WIPO (PCT)
Prior art keywords
pressure
circuit
release
liquid
release valve
Prior art date
Application number
PCT/IB2011/000616
Other languages
English (en)
Other versions
WO2011110946A3 (fr
Original Assignee
Schweyher, Holger
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.)
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Publication date
Application filed by Schweyher, Holger filed Critical Schweyher, Holger
Publication of WO2011110946A2 publication Critical patent/WO2011110946A2/fr
Publication of WO2011110946A3 publication Critical patent/WO2011110946A3/fr

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Classifications

    • 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
    • F24D19/00—Details
    • F24D19/08—Arrangements for drainage, venting or aerating
    • F24D19/082—Arrangements for drainage, venting or aerating for water heating systems
    • F24D19/083—Venting arrangements
    • 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
    • F24D11/002—Central heating systems using heat accumulated in storage masses water heating system
    • F24D11/003—Central heating systems using heat accumulated in storage masses water heating system combined with solar energy
    • 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
    • F24D11/0214—Central heating systems using heat accumulated in storage masses using heat pumps water heating system
    • F24D11/0221—Central heating systems using heat accumulated in storage masses using heat pumps water heating system combined with solar energy
    • 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
    • F24D19/00—Details
    • F24D19/10—Arrangement or mounting of control or safety devices
    • F24D19/1006—Arrangement or mounting of control or safety devices for water heating systems
    • F24D19/1009—Arrangement or mounting of control or safety devices for water heating systems for central heating
    • F24D19/1042—Arrangement or mounting of control or safety devices for water heating systems for central heating the system uses solar energy
    • 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
    • F24D3/00—Hot-water central heating systems
    • F24D3/04—Hot-water central heating systems with the water under high pressure
    • 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
    • F24D3/00—Hot-water central heating systems
    • F24D3/04—Hot-water central heating systems with the water under high pressure
    • F24D3/06—Arrangements or devices for maintaining high pressure
    • 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
    • F24D3/00—Hot-water central heating systems
    • F24D3/10—Feed-line arrangements, e.g. providing for heat-accumulator tanks, expansion tanks ; Hydraulic components of a central heating system
    • F24D3/1008—Feed-line arrangements, e.g. providing for heat-accumulator tanks, expansion tanks ; Hydraulic components of a central heating system expansion tanks
    • F24D3/1016—Tanks having a bladder
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F5/00—Air-conditioning systems or apparatus not covered by F24F1/00 or F24F3/00, e.g. using solar heat or combined with household units such as an oven or water heater
    • F24F5/0007—Air-conditioning systems or apparatus not covered by F24F1/00 or F24F3/00, e.g. using solar heat or combined with household units such as an oven or water heater cooling apparatus specially adapted for use in air-conditioning
    • F24F5/0014—Air-conditioning systems or apparatus not covered by F24F1/00 or F24F3/00, e.g. using solar heat or combined with household units such as an oven or water heater cooling apparatus specially adapted for use in air-conditioning using absorption or desorption
    • 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
    • Y02B10/20—Solar thermal
    • 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]
    • Y02B30/12—Hot water central heating systems using heat pumps

Definitions

  • the disclosed technology relates to heat-exchange circuits of the kind used in heating and cooling systems for buildings.
  • the disclosed technology relates to pressure- release safety valve arrangements in such circuits.
  • FIG. 1 schematically shows a conventional heat-exchange circuit 2 for providing cooling in a building.
  • the heat-exchange circuit 2 is water based and comprises various elements interconnected by pipe work 4 as shown in the figure.
  • the circuit comprises a (heat) storage tank 6, an absorption chiller 8, a solar field water heater 10 and a sealed diaphragm expansion tank 1 provided to accommodate thermal expansion of the water as it is heated.
  • a pressurising pump 12 is provided to pressurise the circuit so the water can be heated to temperatures above 100 °C without boiling.
  • An overflow valve 24 is provided in a branch of the circuit parallel to the pressurising pump 12 and connecting the pressurised side of the pressurising pump 12 to the sealed diaphragm expansion tank 14 on the low pressure side of the pressurising pump 12.
  • the pressurising pump 12 and overflow valve 24 are operated to maintain a desired pressure in the circuit 2 in the normal way.
  • These elements responsible for maintaining the desired pressure may collectively be referred to as a pressurising unit. In normal use for the example shown in Figure 1 the pressurising unit is operated to maintain a water pressure in the circuit of around 15 bar (1.5 Pa).
  • the pressure at the expansion tank 14 (i.e. at the input side to the pressurising pump 12) in this example is below 1.7 bar (0.17 MPa).
  • a heating-loop pump 16 and a cooling-loop pump 18 are provided to respectively circulate water from the storage tank 6 through the solar field heater 10 and absorption chiller 8.
  • the section of the circuit 2 containing the heating-loop pump 16 and solar field heater 10 (with associated connections to the storage tank 6) may be referred to as the circuit's heating loop.
  • the part of the circuit containing the cooling-loop pump 8 and absorption chiller 8 may be referred to as the circuit's cooling loop.
  • a pressure-release safety valve 20 is coupled to the storage tank 6 at a high point in the circuit 2.
  • the safety valve 20 is configured to open and vent the circuit to a blow-down vessel 26 (open to atmospheric pressure) if the internal pressure in the circuit exceeds the valves' release pressure. This is a safety feature aimed at avoiding damage to the circuit, and the associated risk of explosion, in an over-pressure situation.
  • the heating-loop pump 16 is operated to pump water from the bottom of the storage tank 6, through the solar field heater 10, and back to the top of the storage tank 6.
  • the water temperature in the circuit might typically range from around 160 °C to 180 °C.
  • the temperature of the water drawn from the bottom of the storage tank 6 for heating might be around 160 °C and the temperature of the water returned to the top of the water tank after heating in the solar field heater might be around 180 °C.
  • This +20 °C temperature differential across the solar field heater 10 provides the energy input to the circuit.
  • the cooling-loop pump 18 is operated to pump the hot water from the top of the storage tank 6, through the absorption chiller 8, and back to the bottom of the storage tank 6.
  • the temperature of water drawn from the top of the storage tank 6 is around 180 °C.
  • the water is cooled as its thermal energy is used to drive the cooling process in the absorption chiller 8 and is returned to the storage tank at a temperature of around 160 °C.
  • This -20 °C temperature differential across the absorption chiller 8 represents the energy extracted from the circuit which is used to drive the cooling.
  • the absorption chiller 8 is thermally coupled to an air conditioning system of a building (not shown) to provide cooling for the building.
  • circuit 2 of Figure 1 provides a solar-powered cooling system using heated water as a working liquid to provide energy to drive a cooling system.
  • a potential issue with sealed pressurised hot water circuits of the kind shown in Figure 1 is a risk of over-pressure, e.g. in a fault situation.
  • the electric motor of the heating- loop pump 16 of Figure 1 were to fail, the stationary water in the solar field heater 10 would continue to be heated. Eventually this water may become so hot it begins to boil and cause a rapid build-up of pressure in the circuit.
  • the overflow valve 24 may become stuck in a closed state so pressure from the pressuring pump 12 cannot be released.
  • the pressure-release safety valve 20 is provided to reduce the risk of an explosion in these types of situation.
  • the activation pressure for the pressure-release safety valve 20 is 18 bar (1.8 MPa).
  • the safety valve 20 is normally closed. However, if the pressure in the circuit exceed 18 bar (1.8 MPa) because of an over-pressure situation, the safety valve 20 opens to vent the circuit with a view to preventing damage.
  • a country's building code may require pressure-release valves to be provided at high points in the circuit, e.g. above the storage tank 6 as shown in Figure 1.
  • Such valves might also be required at high points in any separately isolatable parts of a pressurised circuit that contain a heater.
  • the heating loop of Figure 1 had valves to allow the solar field heater 10 to be isolated from the storage tank 6, e.g. for maintenance, the isolatable part of the loop containing the heater 10 may also require its own safety release valve.
  • a heat-exchange circuit comprising: a pressurising unit for pressurising liquid in the circuit; a heater for heating the liquid; a first pressure-release valve located at a first position in the circuit and configured to open to release pressure in the circuit if a first pressure threshold is exceeded; and a second pressure-release valve located at a second position in the circuit and configured to open to release pressure in the circuit if a second pressure threshold is exceeded, wherein the second pressure threshold is lower than the first pressure threshold, and wherein the first and second positions are arranged so that in normal use the temperature of the liquid at the second position is lower than the temperature of the liquid at the first position.
  • a circuit may be provided that has a first pressure-release valve positioned to comply with building (boiler) code requirements and a second pressure-release valve arranged in a relatively cool part of the circuit.
  • the second pressure-release valve will open first because of its lower pressure threshold. This allows the circuit to be vented to relieve pressure through the expulsion of cooler liquid than would be expelled if the first pressure-release valve were to be the first to open.
  • the circuit may thus provide a generally safer pressure release mechanism while still complying with the relevant building / boiling codes.
  • the first pressure-release valve may be a full-lift valve, e.g. for building code compliance, while the second pressure-release valve may be a proportional-lift valve. This allows for improved control of the pressure release through the second pressure-release valve in an over-pressure situation which can help to reduce the risk of damage to the circuit still further.
  • the first position may be at a location in the circuit which is higher than the second position.
  • Building codes may require a pressure-release valve to be positioned at a high point in a circuit, and the first pressure-release valve may be located to meet this requirement.
  • the process of gravity driven temperature stratification can naturally help to ensure the temperature at the second pressure-release valve is lower than at the first pressure-release valve.
  • the heat-exchange circuit may further comprise an interception tank arranged between the first and second positions in the circuit and having an upper connection port coupled to a part of the circuit including the first pressure-release valve and a lower connection port coupled to a part of the circuit including the second pressure-release valve.
  • the interception tank may act as a thermal buffer between the hotter parts of the circuit containing the first pressure-release valve and the second pressure-release valve. This can help in some situations where a relatively large amount of liquid may need to be vented to relieve pressure (although in most situations only relatively small amounts of liquid will need to be released to sufficiently reduce pressure).
  • the contents of the interception tank thereby provide a source of cooler water to vent through the second pressure-release valve.
  • the interception tank may, for example, be provided with less thermal insulation than other parts of the circuit, or no thermal insulation at all, such that in normal use the liquid in the interception tank more readily cools to a temperature that is lower than the temperature at the position of the first pressure-release safety valve.
  • the pressurising unit for pressurising liquid in the circuit may also be coupled to a lower connection port at the bottom of the interception tank. This can help isolate the pressurising unit from the hottest parts of the circuit. Furthermore, the pressurising unit may be coupled to an expansion tank to accommodate thermal expansion in the liquid, and the interception tank can thus also help protect the expansion tank from over heating. This can be particularly useful during start-up, for example, when there is likely to be a relatively large transfer of heated liquid to the expansion tank as it undergoes its initial expansion. During steady state operation there is likely to be relatively little transfer between the expansion tank and the rest of the circuit.
  • the first and second positions may be arranged so that in normal use the temperature of the liquid at the first position is above a temperature at which the liquid boils at atmospheric pressure and the temperature of the liquid at the second position is below a temperature at which the liquid boils at atmospheric pressure.
  • the liquid expelled from the second pressure-release valve in an over-pressure situation does not rapidly boil as the valve opens to atmospheric pressure. This helps to reduce the risk of damage to the circuit during pressure release still further since there is reduced risk of spontaneous steam generation.
  • the heat-exchange circuit may further comprise a main storage tank arranged to store heated liquid received from the heater. This may provide thermal store, e.g. to smooth out variations in the thermal input from the heater.
  • the heater may be a solar field heater and the circuit may further comprise an absorption chiller arranged to receive liquid heated by the heater to drive a cooling process, e.g. to cool a building.
  • the storage tank may thus act as a thermal store for the heat from the solar field array so that cooling may continue to be provided through the thermal chiller during periods of diminished sunlight.
  • the first pressure-release safety valve may be located in a branch of the circuit that is connected to an upper port near the top of the main storage tank while the second pressure-release safety valve may be located in a branch of the circuit connected to a lower port near the bottom of the main storage tank. This can help provide the desired difference in temperature between the first and second pressure-release safety valves and also help in complying with good building / boiler practice as regards the position of the first pressure- release safety valve.
  • a method for releasing pressure in a heat-exchange circuit comprising: a pressurising unit for pressurising liquid in the circuit; a heater for heating the liquid; and a first pressure-release valve located at a first position in the circuit and configured to open to release pressure in the circuit if a first pressure threshold is exceeded; and wherein said method comprises: providing a second pressure-release valve located at a second position in the circuit where the temperature of the liquid is lower than the temperature of the liquid at the first position, and opening the second pressure-release valve to release pressure in the circuit when a second pressure threshold is exceeded, wherein the second pressure threshold is lower than the first pressure threshold.
  • Figure 1 schematically shows a conventional solar-powered heat-exchange circuit for providing cooling
  • Figure 2 schematically shows a solar-powered heat-exchange circuit for providing cooling according to an embodiment of the disclosed technology
  • Figure 3 schematically shows in more detail a solar-powered heat-exchange circuit similar to that shown in Figure 2 according to another embodiment of the disclosed technology
  • Figure 4A shows a legend for various ones of the elements of Figure 3;
  • Figure 4B shows a template layout for the two-by-two tables of thermodynamic data shown for various locations in Figure 3.
  • FIG. 2 schematically shows a heat-exchange circuit 102 according to an embodiment of the disclosed technology.
  • the circuit may be used, for example, to providing cooling for a building (not shown).
  • Several elements of the circuit 102 are similar to and will be understood from corresponding elements of the conventional heat-exchange circuit 2 of Figure 1.
  • the heat-exchange circuit 102 is liquid based and comprises various elements interconnected by pipe work 104 as shown in the figure.
  • the working liquid is primarily water (e.g. water plus corrosion inhibitors), but in other situations other liquids could be used.
  • the choice of liquid in a given example may be based, for example, on the same considerations as for a conventional heat-exchange circuit of the kind shown in Figure 1.
  • the circuit comprises a main storage tank 106, an absorption chiller 108, a solar field water heater 110 and a sealed diaphragm expansion tank 114 for accommodating thermal expansion of the water as it is heated.
  • a sealed diaphragm expansion tank 114 for accommodating thermal expansion of the water as it is heated.
  • an open (i.e. non-sealed) expansion tank could be used. In this case it may be appropriate to provide for continuous water treatment, e.g. on-going chemical treatment / degassing.
  • the circuit further comprises an interception tank 130 and a secondary pressure-release safety valve 132 which are discussed further below.
  • a pressurising pump 112 is provided to pressurise the circuit so the water can be heated to temperatures above 100 °C without boiling.
  • An overflow valve 124 is provided in a branch of the circuit parallel to the pressurising pump 112 (i.e. connecting the pressurised side of the pressurising pump 112 to the sealed diaphragm expansion tank 114 on the low pressure side of the pressurising pump 112).
  • the pressurising pump 1 12 and overflow valve 124 are operated to maintain a desired pressure in the circuit 102 in accordance with known techniques.
  • These elements responsible for managing the desired pressure in the circuit may collectively be referred to as a pressurising unit 136.
  • the operation of the pressuring unit 136 may be wholly conventional.
  • a heating-loop pump 116 and a cooling-loop pump 118 are provided to respectively circulate water from the storage tank 106 through the solar field heater 110 and absorption chiller 108.
  • the section of the circuit 102 containing the heating-loop pump 116 and solar field heater 110 (with associated connections to the storage tank 106) may be referred to as the circuit's heating loop.
  • the part of the circuit containing the cooling-loop pump 118 and absorption chiller 108 may be referred to as the circuit's cooling loop.
  • a primary pressure-release safety valve 120 is coupled to the main storage tank 106 at a high point in the circuit 102. This is similar to the safety valve 20 shown in Figure 1 and discussed above.
  • the safety valve 120 is configured to open and vent the circuit 102 to a 1 m 3 blow-down vessel 126 open to atmospheric pressure if the valves' release pressure is exceeded.
  • the primary safety valve 120 in this example is a full-lift valve (i.e. designed to "snap" fully open) and is configured to release pressure in the circuit if the circuit pressure exceeds 18 bar (1.8 MPa).
  • the primary safety valve 120 is a safety feature provided to comply with building code requirements as discussed above.
  • the interception tank 130 is provided in a branch of the circuit 102 between the main storage tank 106 and the pressurising unit 136.
  • the circuit connection between the main storage tank 106 and the interception tank 130 is from the bottom of the main storage tank 106 to an upper port near the top of the interception tank 130.
  • the circuit connection from the interception tank 106 to the pressurising unit 136 is from a lower port near the bottom of the interception tank 130 to the high pressure side of the pressurising unit 136.
  • the secondary safety valve 132 is coupled to the circuit between the interception tank 130 and pressurising unit 136.
  • the secondary safety valve 132 is a proportional release valve (i.e.
  • the pressurising unit is operated to maintain a water pressure in the circuit of around 15 bar (1.5 MPa).
  • the normal operating pressure at the expansion tank 114 i.e. at the input side to the pressurising unit 136) in this embodiment is typically around 1.7 bar (0.17 MPa).
  • the main storage tank 106 is thermally insulated and has a capacity of around 16 m 3 .
  • the pipe work comprising the heating and cooling loops and the connection from the interception tank 130 to the main storage tank 106 is also thermally insulated.
  • the interception tank 130 is not thermally insulated and in this example has a capacity around 2.5 m 3 .
  • the heating-loop pump 116 is operated to pump water from the bottom of the storage tank 106, through the solar field heater 110, and back to the top of the storage tank 106.
  • a typical flow rate provided by the heating-loop pump 1 16 might be around 31 gallons(US)-per-minute (gpm) (117 litres per minute) with a differential pump pressure equivalent to a hydrostatic head of around 3 m.
  • the solar field heater 110 may be any conventional solar heater, for example, based on fluid through a heat exchange element at the focus of a solar reflector.
  • the water temperature in this example circuit 102 typically ranges from around 160 °C to 180 °C.
  • the temperature of the water drawn into the heating loop from the bottom of the main storage tank 106 might be around 160 °C
  • the temperature of the water returned to the top of the water tank after heating in the solar field heater 10 might be around 180 °C.
  • the cooling-loop pump 118 is operated to pump the hot water from the top of the storage tank 106, through the absorption chiller 108, and back to the bottom of the storage tank 106.
  • a typical flow rate provided by the cooling-loop pump 118 might be around 34 gpm (129 litres per minute) with a differential pump pressure equivalent to a hydrostatic head of around 12 m.
  • the absorption chiller 110 may be wholly conventional.
  • the temperature of water drawn from the top of the storage tank 106 is around 180 °C.
  • the water is cooled as its thermal energy is used to drive the cooling process in the absorption chiller 108, and is returned to the storage tank at a temperature of around 160 °C.
  • This -20 °C temperature differential across the absorption chiller 108 represents the energy extracted from the circuit which is used to drive the cooling.
  • the absorption chiller 108 is thermally coupled to an air conditioning system of a building (not shown) to provide cooling for the building.
  • the circuit 102 of Figure 2 provides a solar-powered cooling system using heated water as a working liquid to provide energy to drive a cooling system in a manner that is broadly conventional and similar to that shown in Figure 1.
  • the circuit of Figure 2 behaves differently should an over-pressure situation arise, for example because of a failure / blockage in the over-flow valve 124 in the pressuring unit 136 preventing controlled pressure release back to the expansion chamber 1 1 .
  • the circuit of Figure 2 behaves differently from a conventional circuit in an over-pressure situation because of the different safety valve arrangement.
  • the circuit 102 of Figure 2 comprises a conventionally-located pressure- release safety valve 120 at a high point in the system. This valve is located where the water in the circuit is typically close to its hottest. However, as also noted above, the circuit 102 of Figure 2 further comprises the secondary pressure-release safety valve 132 configured to open at a lower pressure (in this example 17.1 bar (1.71 MPa) as opposed to 18 bar (1.8 MPa)). Significantly, the secondary pressure-release safety valve 132 is located at a point in the heat exchange circuit 102 where the water temperature is lower than at the location of the primary pressure-release safety valve 120.
  • the secondary pressure-release safety valve 132 typically is located at a position that is physically lower in the circuit as compared to the location of the primary pressure-release safety valve 120. Lower locations are generally cooler than higher locations in such circuits in view of gravity-driven temperature stratification effects typically seen in these types of circuit.
  • the secondary pressure-release safety valve 132 may be located at a position where the temperature is lower because of differences in thermal insulation.
  • the temperature at the location of the secondary pressure-release safety valve 132 is low compared to the temperature at the location of the primary pressure-release safety valve 120. This is because of the un-insulated interception tank providing a source of heat loss between the hottest parts of the circuit and the secondary pressure-release safety valve 132.
  • the temperature at the secondary pressure-release valve in the embodiment of Figure 2 might be around 70 D C, for example.
  • the secondary pressure-release safety valve 132 will open to reduce pressure in the circuit 102 when the pressure exceeds 17.1 bar (1.71 MPa).
  • the primary pressure-release safety valve 120 remains closed because its higher release pressure (18 bar (1.8 MPa) in this example) has not been reached.
  • the opening of the secondary pressure-release safety valve 132 releases pressure in the system as water is expelled from the circuit through the open valve.
  • the expelled water at the secondary pressure-release safety valve 132 in this example is at a temperature of only around 70 °C, and so there is no sudden boiling as it is exposed to ambient atmospheric pressure.
  • a heat-exchange circuit that includes a first pressure-release valve located at a first position in the circuit, e.g.
  • the second pressure-release valve is configured to open and release pressure in the circuit if a pressure threshold is exceeded that is lower that the opening-pressure associated with the first pressure-release valve.
  • the locations of the first and second pressure-release valves are such that in normal use the temperature of the liquid at the first location is higher than the temperature of the liquid at the second location.
  • this principle may be embodied in many different pressurised water (liquid) circuits and is not limited to the specific configuration of Figure 2.
  • Figure 2 schematically shows a solar-powered cooling system
  • embodiments of the disclosed technology may equally be applied in a solar-powered heating system, for example with the absorption chiller 108 of Figure 2 replaced with one or more heat radiators internal to a building.
  • the heat exchange circuit need not rely on a solar field heater.
  • a circuit similar to that seen in Figure 2 may be based on an alternative heat source provided to replace, or supplement, the solar field heater 110.
  • FIG. 2 the secondary pressure-release safety valve and the interception tank are located in-line with the pressurising unit 136.
  • This provides an added advantage of providing a temperature buffer (cold buffer) to protect the pressurising unit 136 and expansion tank 114 from high temperature water.
  • a temperature buffer cold buffer
  • the water temperature at the bottom of the interception tank 130 to which the pressurising unit 136 is connected might be only around 70 °C, whereas the pressurising unit in the conventional circuit of Figure 1 will typically be exposed to higher temperatures.
  • the secondary pressure-release safety valve and the interception tank may be provided in a spur to the circuit that is separate from the pressuring unit.
  • the secondary pressure-release safety valve may be located towards the end of an extended un-insulated length of pipe work such that the temperature of the water at secondary pressure-release safety valve is cooler than elsewhere.
  • some form of interception tank may be preferred as it can provide a larger volume of cool water to be expelled through the secondary pressure-release safety valve. This allows pressure to be relieved through continued venting of relatively cool water even in situations where a relatively large amount of water needs to be expelled to relieve the pressure (although in practice only small amounts of water will typically need to be released to relieve sufficient pressure).
  • circuits such as shown in Figure 2 would typically include various additional features, e.g. isolating valves, temperature and pressure sensor, electric motors for the pumps, and so on in line with normal practice for constructing such types of circuits. These are not shown in Figure 2 because they are not directly relevant to the underlying principle of the circuit's operation as described above.
  • Figure 3 shows an engineering schematic diagram of a heat exchange circuit 202 according to another embodiment of the disclosed technology.
  • the circuit 202 of Figure 3 is similar to that of Figure 2 and corresponding elements are identified with the same reference numerals and are not described again in the interest of brevity.
  • the circuit 202 of Figure 3 differs from that of Figure 2 in that it is shown to include various additional elements typically seen in a hot pressurised water circuit.
  • Figure 4A shows the legend for various ones of the elements of Figure 3. These elements are all conventional and may be implemented and operated in the usual way except where described otherwise. The operation of these standard features is not described in detail for brevity.
  • thermodynamic data at various locations in the circuit 202.
  • thermodynamic data are presented in two-by-two tables adjacent the relevant parts of the circuit following the template layout shown in Figure 4B.
  • the top two numbers respectively show the water temperature in °C and pressure in bar
  • the bottom two numbers respectively show the flow rate in kg/h, and the specific enthalpy of the liquid (water) in kJ/kg.
  • the circuit 202 of Figure 3 includes various valves that may be closed to isolate sections of the circuit.
  • the valves 240A and 240B may be used to isolate the heating-loop part of the circuit containing the solar field heater 1 10 from the storage tank 106, e.g. for maintenance.
  • the heating-loop part of the circuit includes a heater and can be isolated from the pressure-release safety valve 120 it is provided with its own pressure-release safety valve 250.
  • This is similar to the primary pressure-release safety valve 120 in that it is provided in accordance with best building practice and is configured to release at the same pressure (in this example 18 bar (1.8 Pa)).
  • the pressure-release safety valve 250 of the heating-loop part of the circuit is also vented to the blow-down vessel 126.
  • the secondary pressure-release safety valve 132 on the cold side of the cold buffer provided by the interception tank 130 will open before either of the two pressure-release safety valves 120, 250 provided in the upper part of the circuit to release pressure with reduced risk of uncontrolled steam generation as described above in relation to Figure 2.
  • the circuit 202 of Figure 3 also includes a pressure-release safety valve 260 on the low-pressure side of the pressurising unit 136.
  • This valve 260 has a release threshold in this example of around 2.5 bar (0.25 MPa) and is provided to protect the low-pressure side of the circuit, e.g. the expansion tank 1 14, from an over-pressure situation in this part of the circuit.
  • the pressure-release safety valve 260 thus performs a role which is different from the role of the secondary pressure-release safety valve 132 that provides a controlled release of pressure in an over-pressure situation in the high pressure side of the circuit (i.e. the secondary pressure-release safety valve 132 has a pressure-release threshold that is higher than the normal operating pressure provided by the pressurising unit to the pressurised part of the circuit).
  • a water-filled heat- exchange circuit comprising a pressurising unit for pressurising liquid in the circuit and a heater for heating the liquid, e.g. a solar field heater.
  • a pressure-release valve is located at a high point in the circuit. This valve is configured to open to release pressure in the circuit if a pressure threshold is exceeded.
  • the circuit additionally comprises a second pressure-release valve that is located at a position in the pressurised circuit where, in normal use, the temperature is lower than at the location of the first pressure-release valve, e.g. because the second pressure-release valve is connected to the remainder of the circuit via a cold buffer, such as an un-insulated interception tank.
  • the second pressure-release valve is furthermore configured to open at a pressure threshold that is lower than that of the first pressure-release valve.
  • a pressure threshold that is lower than that of the first pressure-release valve.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Heat-Pump Type And Storage Water Heaters (AREA)

Abstract

L'invention concerne un circuit d'échange de chaleur rempli d'eau. Le circuit comprend une unité de mise sous pression pour mettre sous pression un liquide présent dans le circuit et un réchauffeur pour chauffer le liquide, par ex., un réchauffeur de champ solaire. Conformément aux règles de l'art de la construction, une soupape régulatrice de pression est située au niveau d'un point haut dans le circuit. La soupape est conçue pour s'ouvrir afin de libérer la pression dans le circuit si un seuil de pression est dépassé. Le circuit comprend en outre une seconde soupape régulatrice de pression qui est située au niveau d'une position dans le circuit sous pression dans lequel, lors d'une utilisation normale, la température est inférieure à celle au niveau de l'emplacement de la première soupape régulatrice de pression, par ex., parce que la seconde soupape régulatrice de pression est reliée au reste du circuit par l'intermédiaire d'un tampon froid, tel qu'un réservoir d'interception non isolé. La seconde soupape régulatrice de pression est en outre conçue pour s'ouvrir à un seuil de pression qui est inférieur à celui de la première soupape régulatrice de pression. Ainsi, dans une situation de surpression, la seconde soupape régulatrice de pression s'ouvre pour libérer la pression avant la première soupape régulatrice de pression. Comme la seconde soupape régulatrice de pression est située au niveau d'un point relativement plus froid dans le circuit que ne le serait une soupape régulatrice de pression classique, le risque d'endommagement causé par une génération de vapeur incontrôlée lorsque la pression est libérée dans une situation de surpression est réduit. En même temps, l'utilisation de la première soupape régulatrice de pression aide à assurer la conformité avec les codes de construction.
PCT/IB2011/000616 2010-03-11 2011-03-09 Circuit d'échange de chaleur WO2011110946A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US31301410P 2010-03-11 2010-03-11
US61/313,014 2010-03-11

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WO2011110946A2 true WO2011110946A2 (fr) 2011-09-15
WO2011110946A3 WO2011110946A3 (fr) 2013-08-08

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ITMO20130220A1 (it) * 2013-08-01 2015-02-02 Cooltech S R L Apparato di pressurizzazione
CN105157005A (zh) * 2015-09-21 2015-12-16 成都申川节能环保工程有限公司 一种基于低频振荡饱和式的太阳能锅炉恒温节能控制***
CN105202513A (zh) * 2015-09-21 2015-12-30 成都申川节能环保工程有限公司 一种集太阳能和锅炉于一体的恒温可控逆变节能控制***
CN105202514A (zh) * 2015-09-21 2015-12-30 成都申川节能环保工程有限公司 一种集太阳能和锅炉于一体的可调式节能控制***
WO2024037620A1 (fr) * 2022-08-18 2024-02-22 厦门科牧智能技术有限公司 Vanne de distribution dotée d'une voie d'eau de décharge de pression externe, système de chasse d'eau de toilettes, et toilettes

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US4278073A (en) * 1979-05-07 1981-07-14 Canzano Pasquale S System, method and apparatus for storing and converting solar energy into heat and/or shaft work
DE19740358C2 (de) * 1997-09-13 2001-03-08 Otto Heat Heizungs-, Energie- Und Anlagentechnik Gmbh & Co. Kg Druckhaltevorrichtung
DE102006021916A1 (de) * 2006-05-11 2007-11-22 Reflex Winkelmann Gmbh & Co. Kg Vorrichtung zur Entgasung und/oder Druckhaltung in einem geschlossenen Wasserkreislauf

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ITMO20130220A1 (it) * 2013-08-01 2015-02-02 Cooltech S R L Apparato di pressurizzazione
CN105157005A (zh) * 2015-09-21 2015-12-16 成都申川节能环保工程有限公司 一种基于低频振荡饱和式的太阳能锅炉恒温节能控制***
CN105202513A (zh) * 2015-09-21 2015-12-30 成都申川节能环保工程有限公司 一种集太阳能和锅炉于一体的恒温可控逆变节能控制***
CN105202514A (zh) * 2015-09-21 2015-12-30 成都申川节能环保工程有限公司 一种集太阳能和锅炉于一体的可调式节能控制***
WO2024037620A1 (fr) * 2022-08-18 2024-02-22 厦门科牧智能技术有限公司 Vanne de distribution dotée d'une voie d'eau de décharge de pression externe, système de chasse d'eau de toilettes, et toilettes

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