EP3879211A1 - Verfahren zur verringerung der eisbildung in kühlaggregaten eines kühlsystems - Google Patents

Verfahren zur verringerung der eisbildung in kühlaggregaten eines kühlsystems Download PDF

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Publication number
EP3879211A1
EP3879211A1 EP21161323.7A EP21161323A EP3879211A1 EP 3879211 A1 EP3879211 A1 EP 3879211A1 EP 21161323 A EP21161323 A EP 21161323A EP 3879211 A1 EP3879211 A1 EP 3879211A1
Authority
EP
European Patent Office
Prior art keywords
defrosting
fan
stage
revolutions
value
Prior art date
Legal status (The legal status 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 status listed.)
Pending
Application number
EP21161323.7A
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English (en)
French (fr)
Inventor
Stefano FILIPPINI
Umberto Merlo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Lu Ve SpA
Original Assignee
Lu Ve SpA
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 Lu Ve SpA filed Critical Lu Ve SpA
Publication of EP3879211A1 publication Critical patent/EP3879211A1/de
Pending legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
    • F25D21/02—Detecting the presence of frost or condensate
    • F25D21/025—Detecting the presence of frost or condensate using air pressure differential detectors
    • 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
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
    • F25D21/002—Defroster control
    • F25D21/006—Defroster control with electronic control circuits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
    • F25D21/06—Removing frost
    • F25D21/08—Removing frost by electric heating

Definitions

  • the present invention relates to an improved process for controlling the formation of frost in cooling units of refrigeration systems.
  • the main purpose of the present invention is to provide an "intelligent" defroster, that is to say a system capable of determining when the optimal time to defrost is, regardless of the time interval elapsed since the previous defrosting cycle.
  • the method according to the invention has the main advantage of automatically determining the moment at which it is necessary to start the defrosting cycle, thus avoiding the system coming into operation if no frost has formed.
  • the method according to the invention lends itself for application to any type of evaporator, regardless of its potential, the refrigerant fluid used, the operating conditions under which it works, the number of compressors with which it is interfaced and the number of evaporators with which it is in parallel.
  • a further advantage of the method according to the invention is the fact that it does not require any calibration, neither by the evaporator manufacturer, nor by the installer, nor by the user.
  • Yet another advantage is the fact that the method according to the invention allows a degree of freedom to the user, who can vary the preset value of the time of the defrosting cycle at will, according to his needs.
  • the method according to the invention has the advantage of allowing to determine and report any non-operation (due to failures or other) of one (or more) fans and one (or more) resistors.
  • the cooling unit 1 illustrated in Figure 1 comprises a heat exchange battery 2 (with the relative exchanger or finned pack, not shown) and a fan 3, advantageously of the axial type, provided with a sensor 4 for measuring the speed of the air entering or exiting the fan in the direction of arrow F.
  • the aforementioned sensor 4 is constituted by a hot wire sensor, for detecting the speed of the air entering or exiting the fan 3. It is positioned radially on the protection / support grid, so as to allow to get an average speed value at the inlet or outlet of the fan.
  • the signal is proportional to the air flow rate, which is taken into account in the method according to the invention.
  • the cooling unit 1 may comprise a sensor 5 for measuring the air pressure in said cooling unit 1, in particular between the heat exchange battery 2 and the fan 3.
  • Figure 8 shows the example of a characteristic curve for fan 3 and the related signal curve of the speed sensor. Means, for example resistors or the like, not illustrated, are also provided for defrosting the heat exchange surfaces.
  • Figure 3 shows the main stages in the method according to the invention, in the form of a flow chart that measures the air speed, i.e., the air flow processed by the fan 3.
  • the value of the air flow rate with a clean battery is entered or acquired. This value is stored and maintained for the entire period of system operation. Then the input values of the following variables are entered: ratio between the final air flow rate (i.e., with frosted battery) and the initial air flow rate (with clean battery), the nominal and maximum rpm that can be reached by the fan 3 and the target defrosting time.
  • the complete logic consists of two main stages:
  • the Input data shown in the diagram in Figure 3 are the following, as set in the system control logic before the refrigeration unit is started:
  • This stage includes the following stages:
  • Stage B is a frosting stage, which occurs when the frost that has formed on heat exchange battery 2 has reached a level such that the fan 3 is no longer able to maintain the initial performance of the refrigeration unit on its own. This stage includes the following stages:
  • stage C includes the following stages:
  • stage A the system continues to monitor the value of the fan revolutions and the air flow rate.
  • the system begins to decrease compared to the clean battery value Vo, this means that frost is forming on the finned pack of the refrigeration unit. Consequently, the system increases the fan revolutions, up to the maximum set value Rpmmax, to keep constant the air flow rate equal to Vo.
  • the system continues to monitor the fan revolutions and the air flow rate. The latter is compared to the initial one with clean battery and when this ratio reaches the set value RVo, the system activates the defrosting stage.
  • a clock measures the defrosting time and when it reaches the set tdefrost value, the defrosting stage ends and all the variables are reset to their initial state.
  • stage C monitors the air flow rate at the end of the defrosting and if said value is lower than that of the clean battery Vo, the defrosting time to is extended. In the next cycle the defrosting time can be adjusted once again to achieve complete cleaning of the finned pack.
  • the reference parameter is the air pressure measured, by the sensor 5 in Figure 1 , in the heat exchange battery 2, in particular between the battery 2 exchanger and the fan 3.
  • the air pressure value with clean battery is initially entered or acquired. This value is stored and maintained for the entire period of system operation. The values of the following variables are then recorded: ratio between the final air pressure (i.e., with frosted battery) and the initial air pressure (with clean battery), the nominal and maximum number of revolutions that can be reached by the fan 3 and the defrosting time.
  • the complete logic consists of two main stages:
  • the Input data shown in the diagram in Figure 5 are the following, as set on the system control logic before starting the refrigeration unit:
  • This stage includes the following stages:
  • Stage B is a frosting stage, which occurs when the frost that has formed on heat exchange battery 2 has reached a level such that the fan 3 is no longer able to maintain the initial performance of the refrigeration unit on its own. This stage includes the following stages:
  • stage C includes the following stages:
  • stage A the system continues to monitor the value of the fan revolutions and the air pressure difference.
  • the system increases the fan revolutions, up to the maximum set value Rpmmax, to keep the air flow rate constant.
  • the second control stage called B
  • the system continues to monitor the fan revolutions and the air pressure difference. This difference is compared to the initial one with clean battery and when said ratio reaches the set value RPo, the system activates the defrosting stage.
  • a clock measures the defrosting time and when it reaches the set tdefrost value, the defrosting stage ends and all the variables are reset to their initial state.
  • stage C monitors the defrosting (cleaning) degree of the refrigeration unit.
  • This stage C monitors the air pressure difference at the end of defrosting and if said value is higher than the ⁇ Pi value of a clean battery, then the defrosting time to is extended. In the next cycle the defrosting time can be adjusted once again to achieve complete cleaning of the finned pack.
  • Figure 7 shows the complete hardware structure of the system for managing a refrigeration plant, consisting of several cooling units 11, 12, 13 and the corresponding general controller 14.
  • the latter may or may not incorporate control of electronic motors 151, 152, 153 and a series of contacts 161, 162, 163 for communication with the respective controllers 171, 172, 173 in the cold room. Communication with these cell controllers can also be performed via a Modbus system (or equivalent).
  • the system includes a series of checks, followed by refrigeration unit operating status alarm signals.
  • the system also constantly monitors the operating status of the fan and the defrosting resistors (or other defrosting devices). A check on possible anomalous formation of frost at the end of defrosting is also provided.

Landscapes

  • 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)
  • Defrosting Systems (AREA)
  • Devices That Are Associated With Refrigeration Equipment (AREA)
  • Sorption Type Refrigeration Machines (AREA)
EP21161323.7A 2020-03-11 2021-03-08 Verfahren zur verringerung der eisbildung in kühlaggregaten eines kühlsystems Pending EP3879211A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
IT102020000005218A IT202000005218A1 (it) 2020-03-11 2020-03-11 Procedimento perfezionato di controllo della formazione della brina nelle unita’ di raffreddamento degli impianti di refrigerazione

Publications (1)

Publication Number Publication Date
EP3879211A1 true EP3879211A1 (de) 2021-09-15

Family

ID=70804979

Family Applications (1)

Application Number Title Priority Date Filing Date
EP21161323.7A Pending EP3879211A1 (de) 2020-03-11 2021-03-08 Verfahren zur verringerung der eisbildung in kühlaggregaten eines kühlsystems

Country Status (2)

Country Link
EP (1) EP3879211A1 (de)
IT (1) IT202000005218A1 (de)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06147602A (ja) * 1992-11-06 1994-05-27 Matsushita Seiko Co Ltd 除霜装置
US5692385A (en) * 1996-01-26 1997-12-02 General Electric Company System and method initiating defrost in response to speed or torque of evaporator motor
DE10315523A1 (de) * 2003-04-04 2004-10-14 BSH Bosch und Siemens Hausgeräte GmbH Kältegerät mit adaptiver Abtauautomatik und Abtauverfahren dafür
JP2011247525A (ja) * 2010-05-28 2011-12-08 Panasonic Corp 冷凍装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06147602A (ja) * 1992-11-06 1994-05-27 Matsushita Seiko Co Ltd 除霜装置
US5692385A (en) * 1996-01-26 1997-12-02 General Electric Company System and method initiating defrost in response to speed or torque of evaporator motor
DE10315523A1 (de) * 2003-04-04 2004-10-14 BSH Bosch und Siemens Hausgeräte GmbH Kältegerät mit adaptiver Abtauautomatik und Abtauverfahren dafür
JP2011247525A (ja) * 2010-05-28 2011-12-08 Panasonic Corp 冷凍装置

Also Published As

Publication number Publication date
IT202000005218A1 (it) 2021-09-11

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