WO2007072523A1 - Systeme de degivrage automatique d'un appareil de refrigeration - Google Patents

Systeme de degivrage automatique d'un appareil de refrigeration Download PDF

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Publication number
WO2007072523A1
WO2007072523A1 PCT/IT2006/000193 IT2006000193W WO2007072523A1 WO 2007072523 A1 WO2007072523 A1 WO 2007072523A1 IT 2006000193 W IT2006000193 W IT 2006000193W WO 2007072523 A1 WO2007072523 A1 WO 2007072523A1
Authority
WO
WIPO (PCT)
Prior art keywords
defrosting
sensor
evaporator
frost
frost level
Prior art date
Application number
PCT/IT2006/000193
Other languages
English (en)
Inventor
Vincenzo Natale
Gennaro Reppucci
Original Assignee
Ixfin S.P.A.
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 Ixfin S.P.A. filed Critical Ixfin S.P.A.
Publication of WO2007072523A1 publication Critical patent/WO2007072523A1/fr

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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
    • 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
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/11—Sensor to detect if defrost is necessary
    • 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
    • F25D2700/00—Means for sensing or measuring; Sensors therefor
    • F25D2700/10—Sensors measuring the temperature of the evaporator

Definitions

  • the present invention concerns a system for automated defrosting of a refrigerating apparatus.
  • the invention concerns a system that realises the automated defrosting of a refrigerating apparatus by using a frost level sensor and a temperature level sensor, the defrosting being activated when the frost level exceeds a frost level threshold and being deactivated when the temperature exceeds a temperature threshold or when the defrosting time exceeds a time threshold.
  • the frost level sensor is preferably optical with emitter/receiver on the same optic axis.
  • the function of defrosting is of particular importance from the energetic and food security point of view. Indeed, the insulating properties of the frost layer which forms on the evaporator bank, normally at ambient air temperature below around 5°C, tend to decrease the thermal exchange, with negative consequences from the point of view of energetic saving, of food conservation and of the life of the system.
  • the defrosting occurs at predefined time intervals, without taking into account the frost level which is actually present; this can involve the activation of the function even in the total absence of frost, with clear waste of energy and wear of the machine.
  • a system for automated defrosting of a refrigerating apparatus characterised in that it comprises at least a frost level sensor placed near the fins of the evaporator of said refrigerating apparatus and at least a sensor of temperature of the evaporator, a central elaboration unit activating the defrosting as soon as the frost level sensed by said at least a frost level sensor exceeds a predefinable frost level threshold, the central unit deactivating the defrosting as soon as the evaporator temperature sensed by said sensor of temperature exceeds a predefinable temperature threshold or as soon as the duration time of defrosting exceeds a predefinable time threshold.
  • said at least a frost level sensor is of the optical type and comprises a emitter/receiver couple on the same optical axis.
  • said at least a sensor of temperature is placed far away from heaters, so as to sense an average temperature.
  • the position of said at least a frost level sensor can be chosen between the begin of the evaporator coil, where a more rapid response of the sensor is obtained, and the end part of the evaporator coil, where a slower response of the sensor is obtained.
  • the distance between said at least a frost level sensor and the evaporator is comprised between 1 and 8 mm.
  • frost level sensors are used, one positioned in front of a side of the evaporator and the other in front of the opposite side, the central unit of elaboration effectuating a weighted average of the two corresponding signals of frost level LF and LR and of the maximum of the these ones according to the following formula:
  • CF, CR, CM being coefficients of the weighted average, in order to obtain a value of the frost level LB to be compared with said predefinable frost level threshold.
  • figure 1 shows a diagram of the probe used in the system according to the invention
  • figure 2 shows an electric diagram of the circuitry in which the probe according to the invention is inserted
  • figure 3 shows a graph of the collector current of figure 2 as a function of the probe according to the invention and the reflecting surface
  • figure 4 shows the progression of the output voltage, as a function of the distance between the probe according to the invention and the reflecting surface
  • figure 5 shows a block diagram of the structure of the regulator of the defrosting
  • figure 6 shows a flow diagram of the processing realised by the intelligent system
  • figure 7 shows a flow diagram of the method of defrosting according to the invention.
  • equal numerical references will be used for indicating equal elements in the figures.
  • the performance of conservation are improved and the consumption are minimised, thanks to the reduction of the number of defrosting cycles.
  • the activation of the defrosting in an optimised way is realised by means of a continuous monitoring of the frost using the probe described in the following, so that the defrosting occurs only when exceeding a predefined level.
  • the probe according to the invention is able to exploit the reflective properties of the frost deposited on the evaporator fins; it is based, therefore, on a sensor of the optical infrared reflective type.
  • This type of sensor is free of faults due to possible deposits of material, which is instead likely in sensors of the transmissive type, which put the emitter/transmitter couple on the same optic axis, normally in a gap of some millimetres.
  • the operative temperature field is suited to the application and ranges between -55 and +85 0 C.
  • the signal emitted from the transmitter, in the absence of reflecting bodies, is not revealed from the receiver; in the presence of frost, on the contrary, the reflected signal returns to the sensor, determining a response as more significant as larger is the reflecting surface and therefore the formed frost layer.
  • the detected signal depends also on the distance between sensor and reflecting body. Therefore, in the installation step, it is important to choose the point that is more suited to detect the formation of frost, the phenomenon being strongly dependent on ambient conditions, on the presence/absence of a air flux and on the possible presence of a light source. Near the beginning of the cooling coil, where the leakage is minimum, the response will be more ready, because of the rapid formation of the frost; on the contrary, near the possible fan the formation will occur late.
  • the probe is for example powered by a continuous voltage of +12V, from which a voltage of +5Vdc is obtained by means of a voltage regulator, constituted by Q1-R1-C1-DZ1.
  • the collector current of the receiver varies as a function of the distance from the reflecting surface, according to the graph reported in figure 3.
  • the current varies linearly in the range 1-8 mm.
  • the resulting signal is suitably amplified and adapted by means of the emitter-follower Q2 (connected to +Vcc on the control plate by means of a resistor); it constitutes the input signal for the analog-digital converter of the micro-controller.
  • figure 4 is reported an example of the progression of the signal provided by Vo, as a function of the thickness of the frost on the evaporator fin, at different distances from the bank.
  • the maximum threshold FTL is determined, expressed as a percentage referred to the presence of frost in the space between two fins of the evaporator.
  • the control system starts the defrosting, that continues according to the provided and available procedures (with electric resistor, by means of inversion of the compressor cycle or by means of stop).
  • the defrosting terminates at the exceeding of the evaporator temperature threshold or in consequence of time-out.
  • the temperature is detected by a proper probe suitably positioned far away from the heaters, in order to provide a representative reading of the average temperature.
  • the second case after a maximum time, usually in case of fault of the first system.
  • the maximum frost threshold FTL and the temperature of end frosting are set up through the user interface.
  • the micro-controller decides whether to start the defrosting and with which procedure (with inversion valve and compressor on, or with thermo-resistor and compressor off).
  • the frost level signals L F and L R coming from the probes on the front and rear of the evaporator, are averaged, or in any case linearly combined according to set up coefficients C F , C R and CM, in order to generate the calculated value L B .
  • the linear combination is the following:
  • LB C F -L F + CR-LR + C M -max(L F ,L R ) Said value LB is continuously compared with the set up threshold level FTL.
  • the state variable is updated in order to indicate the defrosting, and is started the timer of maximum duration.
  • the user sets up the following parameters relevant to the defrosting:
  • DTI defrosting time interval 5 5..
  • the algorithm initially verifies the enabling parameter of the frost probe (H45).
  • frost level probe If the frost level probe is not enabled or is not present:
  • both the time-out (DST), which assures the interruption of the function in case of fault or in any case if it lasts more than a time interval set up by the user, and the temperature of defrosting end (DET) are constantly monitored. If the probe is enabled: • the controller begins monitoring the process, revealing the signal of the frost level; the probe is selected, i.e. the analogical signal Vo is presented at the input of the analog/digital converter;
  • the described control method comprises therefore the starting of defrosting once the frost threshold is exceeded and the termination once the evaporator temperature threshold is exceeded.
  • the defrosting occurs therefore if and only if it is needed and lasts only the time interval needed to restore the efficiency of the thermal exchange of the evaporator.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Defrosting Systems (AREA)

Abstract

L'invention concerne un système de dégivrage automatique pour appareil de réfrigération, caractérisé en ce qu'il comprend un détecteur de niveau de givre disposé près des ailettes de l'évaporateur dudit appareil de réfrigération et au moins un capteur de température de l'évaporateur, une unité centrale qui déclenche le processus de dégivrage dès que le niveau de givre détecté par le détecteur du même nom dépasse un niveau seuil de gel à prédéfinir. L'unité centrale interrompt le processus de dégivrage dès que la température de l'évaporateur captée par la sonde thermométrique dépasse un seuil à définir ou dès que le temps du dégivrage dépasse une durée pouvant être prédéfini.
PCT/IT2006/000193 2005-12-19 2006-03-27 Systeme de degivrage automatique d'un appareil de refrigeration WO2007072523A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITRM20050634 ITRM20050634A1 (it) 2005-12-19 2005-12-19 Sistema per lo sbrinamento automatizzato di un apparato refrigeratore.
ITRM2005A000634 2005-12-19

Publications (1)

Publication Number Publication Date
WO2007072523A1 true WO2007072523A1 (fr) 2007-06-28

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ID=37023085

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IT2006/000193 WO2007072523A1 (fr) 2005-12-19 2006-03-27 Systeme de degivrage automatique d'un appareil de refrigeration

Country Status (2)

Country Link
IT (1) ITRM20050634A1 (fr)
WO (1) WO2007072523A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ITPD20120148A1 (it) * 2012-05-10 2013-11-11 Enerblue S R L Pompa di calore e metodo di controllo dello sbrinamento automatico di una pompa di calore
CN107289693A (zh) * 2017-07-11 2017-10-24 上海理工大学 一种热泵除霜方法
EP2578970B1 (fr) * 2011-10-04 2019-08-14 LG Electronics Inc. -1- Réfrigérateur
US11231219B2 (en) * 2016-11-10 2022-01-25 Lg Electronics Inc. Refrigerator and control method of refrigerator

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3280577A (en) * 1963-11-20 1966-10-25 Matsushita Electric Ind Co Ltd Automatic defrosting control device
US3641781A (en) * 1970-04-22 1972-02-15 Kiyoichi Nijo Method of detecting temperature for controlling a refrigerator or a freezer
US3822560A (en) * 1972-09-29 1974-07-09 Cutler Hammer Inc Defrost sensor and control circuit
US3946286A (en) * 1973-11-08 1976-03-23 Upo Oskeyhtio Device for controlling the formation of frost on cooling radiators and the defrosting of the same
FR2535842A1 (fr) * 1982-11-04 1984-05-11 Jaeger Regulation Dispositif detecteur d'epaisseur de givre
US4450691A (en) * 1982-10-19 1984-05-29 Dectron Inc. Frost detecting device
EP0117425A1 (fr) * 1983-01-29 1984-09-05 Ruhrgas Aktiengesellschaft Transmetteur de signaux pour commander le procédé de dégel sur le côté air d'un évaporateur de pompe de chaleur ou similaire
GB2143945A (en) * 1983-07-26 1985-02-20 Agriculture Fisheries And Food Frost sensor
US4530218A (en) * 1984-02-27 1985-07-23 Whirlpool Corporation Refrigeration apparatus defrost control
US4593533A (en) * 1974-12-05 1986-06-10 Alsenz Richard H Method and apparatus for detecting and controlling the formation of ice or frost
US4663941A (en) * 1985-09-30 1987-05-12 Whirlpool Corporation Refrigerator temperature and defrost control
EP1020149A2 (fr) * 1999-01-15 2000-07-19 Isa SpA Procédé et dispositif pour la commande des conditions frigorifiques dans des modules refroidis
WO2005080891A1 (fr) * 2004-02-19 2005-09-01 Bbc Enterprises, Inc Attache de montage et capteur opto-thermiques

Patent Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3280577A (en) * 1963-11-20 1966-10-25 Matsushita Electric Ind Co Ltd Automatic defrosting control device
US3641781A (en) * 1970-04-22 1972-02-15 Kiyoichi Nijo Method of detecting temperature for controlling a refrigerator or a freezer
US3822560A (en) * 1972-09-29 1974-07-09 Cutler Hammer Inc Defrost sensor and control circuit
US3946286A (en) * 1973-11-08 1976-03-23 Upo Oskeyhtio Device for controlling the formation of frost on cooling radiators and the defrosting of the same
US4593533A (en) * 1974-12-05 1986-06-10 Alsenz Richard H Method and apparatus for detecting and controlling the formation of ice or frost
US4450691A (en) * 1982-10-19 1984-05-29 Dectron Inc. Frost detecting device
FR2535842A1 (fr) * 1982-11-04 1984-05-11 Jaeger Regulation Dispositif detecteur d'epaisseur de givre
EP0117425A1 (fr) * 1983-01-29 1984-09-05 Ruhrgas Aktiengesellschaft Transmetteur de signaux pour commander le procédé de dégel sur le côté air d'un évaporateur de pompe de chaleur ou similaire
GB2143945A (en) * 1983-07-26 1985-02-20 Agriculture Fisheries And Food Frost sensor
US4530218A (en) * 1984-02-27 1985-07-23 Whirlpool Corporation Refrigeration apparatus defrost control
US4663941A (en) * 1985-09-30 1987-05-12 Whirlpool Corporation Refrigerator temperature and defrost control
EP1020149A2 (fr) * 1999-01-15 2000-07-19 Isa SpA Procédé et dispositif pour la commande des conditions frigorifiques dans des modules refroidis
WO2005080891A1 (fr) * 2004-02-19 2005-09-01 Bbc Enterprises, Inc Attache de montage et capteur opto-thermiques

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2578970B1 (fr) * 2011-10-04 2019-08-14 LG Electronics Inc. -1- Réfrigérateur
ITPD20120148A1 (it) * 2012-05-10 2013-11-11 Enerblue S R L Pompa di calore e metodo di controllo dello sbrinamento automatico di una pompa di calore
US11231219B2 (en) * 2016-11-10 2022-01-25 Lg Electronics Inc. Refrigerator and control method of refrigerator
US11940200B2 (en) 2016-11-10 2024-03-26 Lg Electronics Inc. Refrigerator and control method of refrigerator
CN107289693A (zh) * 2017-07-11 2017-10-24 上海理工大学 一种热泵除霜方法

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