Classifications

• • 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
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers
  • F28F19/006—Preventing deposits of ice
• • 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
• • 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 is related to a frost protection device for heat recovery plants.
• Heat recovery plants designed according to the cross flow principle during normal conditions work with warm exhaust air or indoor air is passing through a heat exchanger cassette consisting several flat sheet channels. Cold outside air or supply air passes through a corresponding set of channels in the same heat exchanger.
• the cross section of the heat exchanger cassette normally is rectangular and the exhaust air channels and the supply air channels are arranged alternatively after each other with the distance of a fin spacing.
• the channel walls in the heat exchanger cassette normally is made of aluminium with a small sheet thickness, such as 0,1 mm. In this way heat is transported very quickly and easily through the sheet, from one side to the other side. Normal air velocities in the channels are in the magnitude of 1,5 m/s and the thermal efficiency may be approximately 60%.
• ice may be created in the exhaust air channels of the heat exchanger, which substantially may increase the open area of the channels and possibly plug them.
• a situation typically arises when the outside temperature is below about -8 °C and the relative humidity of the exhaust air is higher than approximately 28%.
• frost and plugging of the exhaust air channels it is known to perform different kinds of measures.
• a fan for the outside air may be stopped when the temperature in the air in the exhaust air channel is sinking below a specific level and again started when the temperature is at an acceptable level.
• a preheating may be initiated when the thermostat indicates that the temperature of the exhaust air has come below a predetermined level.
• a combination of such solutions likewise is possible, preferably in two steps.
• a sensor may registrate a pressure fall which may occur when ice is formed, whereby a timer relay resets the normal function when the ice is molten.
• the closing function will not be necessary as long as the exhaust air is dry, which will be the normal case even on cold winter days.
• the fan for the outside air therefore in such cases should work in normal operation and provide the desired, necessary ventilation balance.
• figure 1 discloses in figure 1 a cross section through a heat exchanger including the frost protection device according to the present invention
• figure 2 discloses an enlarged cross section of the lamella in the heat exchanger cassette, including the sensor for water and condensate.
• Warm exhaust air is sucked by a fan 6 for exhaust air into the heat exchanger, from the room or house, through an exhaust air channel 7, through the heat exchanger cassette 1 and is blown out through the discharge air channel 8.
• Outside air or supply air is sucked by a supply air fan 5 in through an outside air channel 9, through the heat exchanger cassette 1 and is blown into the room through the supply air channel 10.
• exhaust air channels and supply air channels are arranged alternating and divided from each other by channel walls 11.
• a frost protection thermostat 3 preferably is arranged in the exhaust air channel registrating the temperature of the exhaust air and a water and condensate sensor 2 being arranged in an exhaust air channel preferably, registrating possible water in the exhaust air. Furthermore the frost protection thermostat 3 may be arranged in an exhaust air channel or in an exhaust air channel in the heat exchanger cassette together with the water sensor 2. The frost protection thermostat 3 may be arranged in the discharge air channel or in an exhaust air channel together with the water sensor 2.
• the water/condensate sensor 2 which can be seen in a cross section in figure 2, is secured in an exhaust air channel in the heat exchanger cassette, comprising aluminium strips 14 abutting against adjacent cassette walls, electrically isolation 12 arranged on the aluminium strips and a further aluminium layer 15 arranged between the electric isolation layers 12.
• the exhaust air will flow along the edge of the layers 12, 14 and 15 on both sides of these and possibly water or condensate in the exhaust air will settle on the edges of the layers.
• the outer aluminium layer 14 may for example be 0,5 mm aluminium and a voltage of 9 volt may be set between the outer aluminium layers 14 and the center aluminium layer 15.
• the center aluminium layer may be 0,7 mm aluminium.
• An electrical control device 4 also is disclosed in figure 1, controlling the fan function based on the registrations from the water/condensate sensor 2 as well as the frost protec ⁇ tion thermostat 3. Additionally to the sensors disclosed in figure 1, a temperature sensor also may registrate the temperature of the discharged air. Even if the temperature of the discharged air should sink, the supply air fan 5 will continue as long as the water/condensate sensor 2 does not registrate presence of water. of this reason there will be no danger for formation of ice.
• the supply air fan 5 is stopped and first started again when the water sensor 2 does not registrate any water.
• the supply air fan 5 will continue as normally as long as the water sensor 2 does not registrate water or condensate.
• the moist air will condensate immediately when it comes into the heat exchanger cassette 1.
• the water sensor 2 extending through the entire heat exchanger cassette, will secure that the supply air fan 5 is stopped and thereby to avoid further formation of ice.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Thermal Sciences (AREA)
• Combustion & Propulsion (AREA)
• Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Air Conditioning Control Device (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
• Other Air-Conditioning Systems (AREA)
• Greenhouses (AREA)
• Cleaning Of Streets, Tracks, Or Beaches (AREA)
• Defrosting Systems (AREA)
• Buildings Adapted To Withstand Abnormal External Influences (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=19897117

Family Applications (1)

Country Status (7)

Cited By (4)

Families Citing this family (4)

Citations (4)

Family Cites Families (1)

• 1994
  • 1994-05-24 NO NO941913A patent/NO179227C/no not_active IP Right Cessation
• 1995
  • 1995-05-23 DE DE19581673T patent/DE19581673C2/de not_active Expired - Lifetime
  • 1995-05-23 AU AU25808/95A patent/AU2580895A/en not_active Abandoned
  • 1995-05-23 WO PCT/NO1995/000080 patent/WO1995032398A1/en active IP Right Grant
• 1996
  • 1996-11-21 DK DK199601330A patent/DK172963B1/da not_active IP Right Cessation
  • 1996-11-22 FI FI964671A patent/FI117647B/sv not_active IP Right Cessation
  • 1996-11-22 SE SE9604294A patent/SE507110C2/sv not_active IP Right Cessation

Patent Citations (4)

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