Classifications

• • 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
  • F24F5/0035—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 evaporation
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
  • F24F1/00—Room units for air-conditioning, e.g. separate or self-contained units or units receiving primary air from a central station
  • F24F1/0007—Indoor units, e.g. fan coil units
  • F24F1/0059—Indoor units, e.g. fan coil units characterised by heat exchangers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
  • F24F1/00—Room units for air-conditioning, e.g. separate or self-contained units or units receiving primary air from a central station
  • F24F1/0007—Indoor units, e.g. fan coil units
• • 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
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D5/00—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, using the cooling effect of natural or forced evaporation
• • 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
  • F24F2012/007—Use of energy recovery systems in air conditioning, ventilation or screening with heat-exchange between supplied and exhausted air using a by-pass for bypassing the heat-exchanger
• • 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]
  • Y02B30/54—Free-cooling systems
• • 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 invention relates to a method for cooling a supply air flow for a room by means of an exhaust air flow which is returned via a plate heat exchanger, water being sprayed upstream into the exhaust air ducts in such a way that the surface elements always remain moist but practically no water drips off.
• heating and / or cooling systems are used to air-condition living rooms, work rooms and storage rooms, as well as temperature-sensitive objects, which not only cause a relatively high energy consumption for heating but also for cooling.
• the recycling principle has also found its way into this area within the framework of increasingly strict ecological framework conditions, paired with relatively high energy costs.
• the exhaust air is used to pre-cool or preheat the outside air flow - called supply air after the plate heat exchanger.
• the supply air and exhaust air flows are strictly separated with the largest possible exchange areas.
• the plate heat exchangers frequently used for this work on the counterflow principle or preferably on the crossflow principle.
• a plate heat exchanger for ventilation systems is described for example in EP 0449783 A2.
• This heat exchanger consists of surface elements of identical shape stacked at a distance from one another by means of inserted or shaped spacers. Thanks to the thin surface elements and the spaces, which are usually only about 2 to 15 mm wide, this cross-flow heat exchanger enables effective heat transfer from the two crossing air flows.
• the foils for example about 0.1 to 0.5 mm thick, preferably consist of a metal that is a good conductor of heat, such as Aluminum or steel, but also made of mechanically strong plastic or a composite material.
• Spraying is preferably carried out on the exhaust air inlet side.
• a spray cone is directed at the surface elements, the spray water drips off on the outlet side of the exhaust air, is collected and, as a rule, pumped back in a circulatory system.
• the surface elements are cooled by heat convection and partial evaporation of the water and heat is extracted from the outside air flow crossing on the other side of the surface elements, without influencing its moisture balance.
• EP 0800641 B1 describes a method and a device which allow a notable increase in the efficiency of the cooling water used. Wetting nozzles spray upstream at the same time intervals in a fine spray of treated water into the exhaust air flow channels of the plate heat exchanger. The amount of spray water is dosed so that practically no sprayed water drips off, but the surface elements covered with exhaust air remain moist until the next spraying. At the end of a daily cooling period, flushing nozzles also spray upstream a hard spray of tap water into the exhaust air flow channels of the plate heat exchanger, which is cleaned in this way. A corresponding "softcool" system is offered by the company polybloc AG, CH-8404 Winterthur. Different types of cross-flow plate heat exchangers are manufactured, also with an integrated bypass for power regulation and / or reduction of the pressure drop in the supply air flow.
• the inventor has set himself the task of further improving the method described at the outset for cooling a supply air flow for a room by means of an exhaust air flow and, in particular, of increasing the efficiency in a simple manner.
• the object is achieved in that the exhaust air flow, which flows back through the water-sprayed exhaust air channels of the plate heat exchanger, is reduced with respect to the supply air flow.
• the cooling capacity of the system can be significantly increased if the volume of the exhaust air flow is markedly reduced compared to the supply air flow.
• the exhaust air flow returned through the exhaust air channels of the plate heat exchanger sprayed with water is reduced by at least 50%.
• optimal results can be produced if the exhaust air flow returned through the sprayed exhaust air ducts is reduced in volume by 70 to 80%, preferably by about 75%.
• Supply air and extract air are preferably led in cross flow through a plate heat exchanger. With this reduction of the exhaust air flow to a volume of about 25% of the supply air flow, such a high degree of efficiency is achieved that the outside air is cooled 2 to 3 ° C more than with the same large supply air and exhaust air volume flow.
• a clean exhaust air flow for example the exhaust air from inhabited rooms, can partially be released directly into the atmosphere, for example via a branch with an adjustable air flap.
• the exhaust air is returned via a bypass past the plate heat exchanger and, if necessary, is passed through a cleaning system together with the exhaust air from the plate heat exchanger as the entire exhaust air.
• some of the exhaust air is naturally diverted in a controlled manner via the bypass, again preferably with a branch and an adjustable air flap.
• the exhaust air duct can be routed around the plate heat exchanger, but the plate heat exchanger is preferably designed so that the bypass is integrated in the same housing.
• Inlet flaps for the sprayed exhaust air ducts and the bypass are expediently arranged such that they can be actuated in combination with one another.
• the bypass is opened to the same extent as the exhaust air ducts are closed.
• Similar plate heat exchangers are known per se, but - as already mentioned - they are only used for power control with reference to the supply air flow.
• FIG. 1 is a schematic diagram of an evaporative cooling system with a reduced clean exhaust air flow
• FIG. 2 shows a variant of FIG. 1 with an exhaust air flow that is partially conducted via a bypass
• FIG. 3 shows a variant of FIG. 2 with a bypass integrated in the plate heat exchanger
• FIG. 4 is a perspective view of a housing with a plate heat exchanger
• FIG. 5 shows a variant according to FIG. 4 with a diagonally inserted plate heat exchanger
• FIG. 6 shows a Mollier-h-x diagram for moist air.
• FIG. 1 shows a plate heat exchanger 10 known per se with a vertically presented, parallel surface elements 36 (Fig. 4). With a completely closed air flap 14, an exhaust air flow 12 is directed exclusively through the plate heat exchanger 10, from which it exits as an exhaust air flow 16.
• a traveling nozzle bar 18 Arranged on the inlet side of the exhaust air flow 12 is a traveling nozzle bar 18 with three low-power wetting nozzles 20 designed as flat jet nozzles, each of which spray a spray cone of water 32 into the inlet openings of the exhaust air channels 42 (FIG. 4) of the plate heat exchanger 10.
• Each wetting nozzle 20 has a further flat jet nozzle of high output, a flushing nozzle 22, for cleaning the plate heat exchanger 10, which latter nozzles 22, however, do not play an important role in the invention.
• An outside air flow 24 flows crosswise with respect to the exhaust air flow 12 through the plate heat exchanger 10 and is cooled there, for example, from about 32 ° to about 22 ° C., the outside air flow 24 becomes the supply air flow 26 for a room 28. After some time, for example after 5 to 10 minutes , the supply air 26 has passed through the room 28 and is supplied as a heated exhaust air flow 12 with a temperature of, for example, approximately 26 ° C. to the plate heat exchanger 10, cooled there with spray water 32 as described above and discharged as exhaust air 16.
• the exhaust air flow 12 immediately after the space 28 has a branch line 30 with the air flap 14.
• the branch line 30 and the air flap 14 are dimensioned such that they take over the greater part of the exhaust air flow and can derive.
• the air flap 14 is opened in such a way that at least 50% of the exhaust air 12 from the room 28 flows out via the branch line 30, in the present case approximately 75%.
• the reduced exhaust air flow 12 provides a significantly better cooling performance in the plate heat exchanger 10 than the full exhaust air flow.
• the water 32 sprayed by the wetting nozzles 20 onto the surface elements 36 (FIG. 4) can are better vaporized.
• the exhaust air 12 branched off via the branch line 30 in accordance with the position of the air flap 14 is not discharged into the atmosphere, but is conducted via a bypass 34 around the plate heat exchanger 10 and fed back to the exhaust air flow 16. According to this variant, too, the greater part of the exhaust air passes through the bypass 34. The same improved cooling effect as in FIG. 1 is achieved.
• the embodiment according to FIG. 2 can be used for all exhaust air qualities, in particular for contaminated exhaust air 12, which according to the embodiment according to FIG. 1 would have to be treated separately.
• the surface elements 36 do not run parallel to the plane of the drawing as in FIGS. 1 and 2, but perpendicular to them.
• a bypass 34 is provided in the plate heat exchanger for a part of the exhaust air flow 12 which can be adjusted by means of the air flap 14 and which is supplied via the branch line 30. Again, at least half of the exhaust air flow 12 is removed. The cooling effect of the reduced exhaust air flow 12 remains the same as in FIGS. 1 and 2.
• surface elements 36 form, in a manner known per se, intersecting, mutually closed air channels 40, 42, which alternate for the outside air flow 24 / supply air flow 26 on the one hand and the exhaust air flow 12 / exhaust air flow 16 are open.
• the exhaust air ducts 42 are closed and the supply air ducts 40 are open.
• the bypass 34 which runs parallel to the air channels 40, 42, is separated by a partition 44.
• the exhaust air flow 12 (FIGS. 1 to 3) is through through adjustable inlet flaps 46 the exhaust air ducts 42 and through inlet flaps 48 the exhaust air flow 12 through the bypass 34 are adjustable.
• the inlet flaps 48 are closed and the inlet flaps 46 are open, the entire exhaust air flow 12 passes through the exhaust air channels 42 of the plate heat exchanger. If the inlet flaps 48 are open and the inlet flaps 46 are closed, the entire exhaust air flow 12 passes through the bypass 34, it is not cooled.
• the optimal setting of the rigidly interconnected air flaps 46, 48 can be determined by calculations and / or series of tests.
• the surface elements 36 and thus the supply air ducts 40 and the exhaust air ducts 42 are arranged diagonally.
• Inlet flaps 46, 48 for the exhaust air flow 12 (FIGS. 1 to 3) are again arranged.
• the inlet flaps 46 for the area of the surface elements 36 and the inlet flaps 48 for the bypass 34 are rigidly connected to one another via a common pivot axis 50. If, for example, the inlet flaps 46 are partially closed, the inlet flaps 48 are automatically opened in a coordinated manner. In the two end positions, one flap 46 or 48 is always open, the other flaps 48 or 46 are closed.
• the status curve 2 results for the outside air, it is one Temperature T cooled from about 32 ° C to about 24 ° C.
• State curve 1 results for the exhaust air, which is heated from approximately 26 to approximately 27 ° C.
• the exhaust air exits with a relative humidity F of about 68%, so it is far from saturation.
• the amount of water W evaporated is approximately 2.5 g / kg.
• the temperature T is reduced in accordance with the state profile 3 from approximately 32 ° C. to 21.7 ° C., that is approximately 2.3 ° C. more than with the same supply air and exhaust air flow in accordance with the state profile 2.
• the state curve 4 for the exhaust air shows that the saturation limit S is almost reached with the reduced supply air flow through the plate heat exchanger. About 15 g / kg of water W are evaporated.
• the thermal utilization of the exhaust air also reaches a very high value, as the state curve 5 shows with regard to the enthalpy E.

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Publications (1)

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ID=34812824

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Cited By (10)

Citations (8)

Family Cites Families (2)

• 2004
  • 2004-01-30 CH CH00135/04A patent/CH697104A5/de not_active IP Right Cessation
  • 2004-11-05 WO PCT/CH2004/000673 patent/WO2005073656A1/de not_active Application Discontinuation
  • 2004-11-05 EP EP04797230A patent/EP1709379A1/de not_active Withdrawn

Patent Citations (8)

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