EP3879211A1 - Procédé de contrôle de la formation de givre dans unités de refroidissement en systèmes de réfrigération - Google Patents
Procédé de contrôle de la formation de givre dans unités de refroidissement en systèmes de réfrigération Download PDFInfo
- 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
Links
- 238000000034 method Methods 0.000 title claims abstract description 43
- 238000001816 cooling Methods 0.000 title claims abstract description 24
- 238000005057 refrigeration Methods 0.000 title claims abstract description 24
- 230000015572 biosynthetic process Effects 0.000 title claims abstract description 20
- 238000010257 thawing Methods 0.000 claims abstract description 93
- 238000012544 monitoring process Methods 0.000 claims description 16
- 238000004140 cleaning Methods 0.000 claims description 11
- 230000007423 decrease Effects 0.000 claims description 5
- 230000002547 anomalous effect Effects 0.000 claims description 2
- 238000010586 diagram Methods 0.000 description 5
- 230000002411 adverse Effects 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000004378 air conditioning Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 239000003507 refrigerant Substances 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
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)
- Sorption Type Refrigeration Machines (AREA)
- Devices That Are Associated With Refrigeration Equipment (AREA)
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 (fr) | 2021-09-15 |
Family
ID=70804979
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP21161323.7A Pending EP3879211A1 (fr) | 2020-03-11 | 2021-03-08 | Procédé de contrôle de la formation de givre dans unités de refroidissement en systèmes de réfrigération |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP3879211A1 (fr) |
IT (1) | IT202000005218A1 (fr) |
Citations (4)
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 |
-
2020
- 2020-03-11 IT IT102020000005218A patent/IT202000005218A1/it unknown
-
2021
- 2021-03-08 EP EP21161323.7A patent/EP3879211A1/fr active Pending
Patent Citations (4)
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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