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
  • F25D29/00—Arrangement or mounting of control or safety devices
• • 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
  • F25D17/00—Arrangements for circulating cooling fluids; Arrangements for circulating gas, e.g. air, within refrigerated spaces
  • F25D17/04—Arrangements for circulating cooling fluids; Arrangements for circulating gas, e.g. air, within refrigerated spaces for circulating air, e.g. by convection
  • F25D17/06—Arrangements for circulating cooling fluids; Arrangements for circulating gas, e.g. air, within refrigerated spaces for circulating air, e.g. by convection by forced circulation
• • 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
  • F25D2400/00—General features of, or devices for refrigerators, cold rooms, ice-boxes, or for cooling or freezing apparatus not covered by any other subclass
  • F25D2400/30—Quick 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
  • F25D2700/00—Means for sensing or measuring; Sensors therefor
  • F25D2700/12—Sensors measuring the inside temperature
• • 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
  • F25D2700/16—Sensors measuring the temperature of products

Definitions

• the present invention relates to a method for controlling the rapid cooling of a rapid cooling cell for use in commercial catering, catering and agribusiness and a device for its implementation.
• the objective of rapid cooling is to prevent food products after cooking remain at a temperature that promotes the multiplication of microorganisms responsible for food poisoning, for too long.
• regulations, recommendations or guidelines of good practice specify the duration not to be exceeded between a core temperature and a core temperature.
• the French regulation of 1997 stipulates a maximum duration of 2 hours between + 63 ° C and + 10 ° C at heart whereas in the USA, it is referred to a maximum duration of 4 hours between + 60 ° C and + 4 ° C.
• the rapid cooling / freezing cells consist mainly of an isothermal enclosure, a powerful device for circulating the indoor air, a cold production equipment with its heat exchanger placed inside the enclosure isothermal and a control device, usually electronic type, managing all.
• the technique of rapid cooling is constrained by two contradictory objectives.
• the first is quantitative and consists in cooling the food product between two values of core temperatures, in a maximum duration for a food safety objective. This may require producing low air temperatures, much lower than 0 0 C.
• the second is qualitative and consists in avoiding the freezing on the surface of the food product to be cooled in order to avoid a dangerous modification of structure altering its quality. This implies to prevent an air temperature too low and / or for too long a duration. There is a risk of freezing the surface of the product as soon as the air temperature on the product is below - 2 ° C.
• a low air temperature is required when using a cell at its nominal capacity or when short cooling times are required or to reach a final core temperature. close to 0 ° C or for thick products or for products with unfavorable packaging for heat exchange. But in everyday use, it is frequently unnecessary to produce a low air temperature to achieve this goal. This is the case when loading a small quantity of product into the apparatus or loading a product that is easy to cool, or to reach a final core temperature well above 0 ° C. or when a long duration of cooling is permissible. The cell is then in a situation of suipuissance. The consequence is a very rapid drop in the temperature of the air, much faster than that of the temperature at heart. In the end, the product is cooled in a much shorter time than the maximum required but is partially frozen at the surface.
• Cold production equipment can also lead to a situation of overpower, producing the same effects as the low load of the device. This is because of the power of the cold-generating equipment that is greater than that required to cool the rated capacity of the appliance, either as a result of a voluntary choice or a poor evaluation of the characteristics of the installation. as a result of a variation in power of the cold production equipment between summer and winter. Equipment selected for an exceptionally hot summer will be much more powerful in the winter months due to low outdoor temperatures.
• stinging probes inserted in the food product throughout the rapid cooling phase. These probes continuously measure the core temperature of the product and determine the arrival at the desired final core temperature. Once at the final core temperature, the controller switches the device to a holding position at a positive temperature (above 0 ° C) or stops the device. The direct measurement of the core temperature of the product makes it possible to interrupt the rapid cooling phase at the right moment, whatever the characteristics of the product or the device.
• these probing probes allow only the control of the objective of food safety. Even today, a number of fast cooling / freezing cell manufacturers are content with this objective.
• control devices have been developed for many years in order to reduce the risk of freezing. area. These control devices have programmed functions allowing:
• the air temperature can not fall below a determined value, a switching being also possible between several air temperature limitations during cooling , based on the crossing of one or more thresholds on the air temperature and / or the core temperature and / or the time elapsed since the start of cooling;
• This prick probe and control device assembly is commonly referred to as an autopilot device.
• the first solution is to propose a fixed value.
• typical values stored in the control device are used.
• the values of air temperature limitations, air flow reduction and switching thresholds are determined by prior experimentation.
• the different values are often modifiable, but difficult for a daily user of the device. This is necessarily a compromise that favors the objective of food safety at the expense of the risk of freezing the surface of the product. As a result, it often fails to achieve the qualitative objective of avoiding freezing of the product surface.
• Another solution proposes a touch of limitation of the air temperature close to 0 0 C or reduction of the air circulation.
• the user selects on the control panel, by pressing a key, an operation of the device with an air temperature limitation close to 0 ° C or a reduction of air circulation. Therefore, the user must appreciate the mass of food product, the thermal behavior of the food product, the packaging and the cooling cell to make a decision. If this limitation of the air temperature close to 0 ° C or a low airflow is selected while a product that is difficult to cool is in the unit, the cooling time will exceed the maximum time required. This can lead to a failure of the food safety objective of rapid cooling.
• the last solution is that the user selects on the control panel, by pressing keys, a program (from a set of programs) in which is stored one or more sequences of values for limiting the temperature of the air and / or reducing the air flow and their switching thresholds. Therefore, the decision of the user must appreciate the mass of food product, the thermal behavior of the food product, the packaging and the cooling cell. Improper user appreciation will result in either freezing of the surface of the product or a cooling time longer than the maximum duration required. This solution can then lead either to the failure of the food security objective or to the failure of the qualitative objective.
• the object of the present invention is therefore to propose a method for controlling the cooling means of a fast cooling cell making it possible to achieve a cooling time that is less than or equal to the maximum duration required, with an air temperature within the the coldest possible enclosure, without any action or decision on the part of the user, whatever the product, its structure, the mass of product in the device, the thickness of the product, the packaging of the product, the capacity of the device, etc.
• the present invention compared to all current control devices, thus ensures the quality of the product (not freezing the product on the surface) and corrects what is not achieved by the control device called automatic control.
• the subject of the invention is a method for controlling a fast cooling cell of a product resulting from cooking with a view to its preservation, composed mainly of an isothermal enclosure, a circulation device of air, a cold-generating equipment with its heat exchanger placed, in general, inside the insulated enclosure and at least one plug-in probe inserted into the core of the product, characterized in that a periodic reading is made of the temperature at the core of the product to be cooled and the temperature of the ambient air in the enclosure, and in that from said temperature measurements a reference value of the temperature of the temperature is determined.
• this set point of the temperature of the ambient air within of the enclosure for controlling the cold producing equipment until the end of the cooling cycle to reach a core temperature at the end of the cycle less than a predetermined final core temperature with a cycle time of less than or equal to a predetermined maximum cycle time.
• control method makes it possible to determine a set value of the air temperature within the enclosure making it possible to control the rapid cooling conditions of the product within the predetermined maximum duration by reducing at least the risk of freezing the surface of the product regardless of the product, the packaging of the product, the mass of the product in the cooling cell, the capacity of the cell, the actual filling of the cell.
• the control method according to the invention therefore allows self-cooling automatically adapting to the product to be cooled, whatever the product, the product packaging, the mass of the product in the cooling cell, the capacity of the cell, the actual filling of the cell and thus, that is to say, regardless of the type of product, the packaging of the product, the mass of the product in the cooling cell, the capacity of the cell, and the effective filling of the cell.
• the set point of the ambient air temperature within the enclosure is as close as possible to 0 ° C.
• control method according to the invention advantageously allows the operation of cooling cells even at low capacity.
• the set value of the air temperature can be called also, the limitation of the air temperature in the enclosure is self adapted according to the method of the invention regardless of the type of product, packaging , total mass of product in the cell, cooling capacity variation between summer and winter.
• This set point of the air temperature corresponds to the temperature at which the cooling compressor of the cooling means for example will stop and start.
• said measured values are processed so as to determine:
• the periodic temperature record is made every minute.
• a temperature value at the beginning of the cycle of the product to be cooled and a final core temperature value of said predetermined product are predetermined, as well as a maximum cycle time to pass from the product. one to the other of these temperatures and therefore a maximum arrival time calculated to reach the predetermined final core temperature.
• the control method according to the invention has, from the beginning of the cooling cycle, the following steps of determining the set point of the ambient air temperature at each reading of the core temperatures and the air temperatures. of the enclosure.
• the value of the measured air temperature Ta is compared with a reference value of the air temperature, Tar. As long as the measured temperature of the air Ta is greater than this reference value of the temperature Tar, the comparison between the measured air temperature and the reference value of the air temperature at each new reading is repeated. temperatures.
• the reference value of the ambient air temperature Tar is 0 ° C.
• the next step is to compare the calculated arrival time with the predetermined final core temperature. at the calculated maximum arrival time. As long as the calculated time of arrival at the predetermined final core temperature is greater than the calculated maximum arrival time, the comparison is repeated at each new temperature reading until the calculated time of arrival at the predetermined final core temperature is less than the calculated maximum arrival time. As soon as this comparison is validated, the slope of the variation of the calculated arrival time is compared with the predetermined final core temperature at a predefined threshold value.
• the set point of the air temperature is determined at 0 ° C and continued the cycle at this setpoint until the core temperature of the product is lower than the predetermined final core temperature.
• the slope of the variation of the calculated time of arrival at the predetermined final core temperature is not greater than the predefined threshold value, then it follows that the slope is too great and that in this case the calculated time of arrival at the predetermined final core temperature will be well below the calculated maximum arrival time, which makes it possible to set the air temperature setpoint at 0 ° as of now. C and thus continue the cycle to this setpoint until the core temperature of the product is lower than the predetermined final core temperature.
• the set value of the air temperature is determined at said fixed predetermined value (-20 ° C.) and then the value is determined set point of the air temperature at 0 0 C when the core temperature measured reaches a predetermined fixed value such as for example 15 ° C.
• the calculated time of arrival at the temperature at predetermined final core to the average value of the calculated time of arrival at the predetermined final core temperature plus or minus a stabilization tolerance value of the calculated time of arrival at the predetermined final core temperature, this value of tolerance being defined beforehand.
• the comparison is repeated at each new temperature reading.
• said measured values can be processed so as to optionally also determine the slope of the variation of the air temperature measured in the chamber, and the stability of said slope, and in that once the stability of the slope of the variation of the calculated time of arrival at the predetermined final core temperature has been ascertained, it can be determined that the slope of variation of the temperature of the measured air decreases steadily. As long as this stability of the slope of the air temperatures of the enclosure is not reached, this step can be repeated.
• the temperature of the enclosure air is then determined when the predetermined final core temperature is reached as the predetermined final core temperature minus the predicted difference between the core temperature and the air temperature at the end. maximum arrival time calculated.
• This temperature of the air of the chamber is then compared when the predetermined final core temperature is reached at the measured air temperature of the chamber. If said temperature is not greater than or equal to the measured air temperature of the enclosure, the steps are repeated from that of determining the stability of the slope of the change in ambient air temperature for each new air temperature readings and at the core.
• the air temperature of the enclosure when reaching the predetermined final core temperature is found to be equal to or greater than that of the measured air of the enclosure, it is the temperature setpoint of the enclosure. air from the enclosure serving as a basis for controlling the cooling means for the continuation of the cooling cycle until the measured core temperature is lower than the predetermined final core temperature.
• the set point of the air temperature serving as a basis for the control of the cooling means for the continuation of the cooling cycle is calculated higher than 0 ° C, said setpoint value is considered equal to 0 ° C. This setpoint can never be greater than 0 ° C.
• the maximum duration of the predefined cycle is initialized to zero.
• the measured core temperature is then compared with the predefined start cycle temperature.
• the maximum cycle time is equal to the predefined cycle time.
• the maximum cycle time is defined as the ratio of the product of the predefined cycle time to the measured core temperature minus the preset end-of-cycle core temperature to the cycle start core temperature minus the predefined end-of-cycle core temperature.
• control method of the cooling means leads to an "analysis" of the product to be cooled.
• the subject of the present invention is also a device for controlling a fast cooling cell of a product resulting from cooking with a view to its preservation, composed mainly of an isothermal enclosure, an indoor air circulation device. , a cold production equipment with its heat exchanger placed inside the isothermal enclosure and at least one plug-in probe inserted into the core of the product, characterized in that it comprises means for periodic measurement the core temperature and the temperature of the air in the enclosure, storage means for storing said temperature measurements, means for processing the temperature measurements making it possible to determine a set value of the air temperature of the the enclosure, this setpoint of the air temperature of the enclosure serving to automatically control the cold production equipment until the end of the cooling cycle for att set a core temperature at the end of the cycle lower than a predetermined final core temperature with a cycle time less than or equal to a predetermined maximum cycle time.
• the means for processing the temperatures recorded comprise calculation means making it possible, from the measured measurements, to determine the difference between the measured core temperature and the measured air temperature of the enclosure, the calculated time ( predicted) of arrival at the predetermined final core temperature, from core temperatures measured as a function of time, an average value of the calculated time of arrival at the predetermined final core temperature, the slope of the variation of the time of arrival at the predetermined final core temperature, and the difference between the core temperature and the air temperature at the calculated maximum arrival time, calculated from the difference between the core temperature measured and the measured air temperature of the enclosure as a function of time.
• the means for processing the measured temperatures comprise calculation means making it possible, from the measurements noted, to determine the slope of the variation of the temperature of the air and the stability of said slope.
• the processing means further comprise means for comparing said measured temperature measurements, said calculations made from said measured temperatures and predefined values.
• the calculation means may advantageously comprise mathematical regressions.
• an exponential regression of the measured core temperature as a function of time can be used to determine the calculated time of arrival at the predetermined final core temperature, and a linear regression of the difference between the temperature at measured heart and the measured air temperature of the enclosure as a function of time to determine the difference between the core temperature and the air temperature at the calculated maximum arrival time.
• the invention therefore also relates to a rapid cooling cell of a product from cooking for its preservation, composed mainly of an isothermal enclosure, an indoor air circulation device, a production equipment cold with its heat exchanger placed inside the isothermal enclosure and one or more insertion probe inserted into the heart of the product, comprising means adapted to implement the method according to the invention.
• the invention also relates to a corresponding computer product, that is to say the product that can be loaded directly into the memory of a computer and which includes parts of software for implementing the method according to the invention when the product is designed to operate on a computer, which is part of the control device of the cooling cell.
• a corresponding computer product that is to say the product that can be loaded directly into the memory of a computer and which includes parts of software for implementing the method according to the invention when the product is designed to operate on a computer, which is part of the control device of the cooling cell.
• Cooling the cell shown in the example operates at low capacity, that is to say, the charging of the cell is 1 A of the nominal load, here 13 kg.
• the maximum cycle time for rapid cooling is set at 110 min. It can be seen that the cooling time in automatic control is 86 minutes and the ambient air temperature is allowed to go down to -18 ° C (curve 1).
• the control method according to the invention makes it possible to determine a set point of the ambient air temperature at -5 ° C., approximately 30 minutes after the start of the cooling cell, and this value is respected by the regulation automatic compressor until the end of the cooling cycle which is here 91 min (curve 2).

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• Engineering & Computer Science (AREA)
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• Combustion & Propulsion (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Devices That Are Associated With Refrigeration Equipment (AREA)
• Fuel Cell (AREA)

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• 2005
  • 2005-10-05 FR FR0510183A patent/FR2891613B1/fr not_active Expired - Fee Related
• 2006
  • 2006-10-05 AT AT06808234T patent/ATE421667T1/de not_active IP Right Cessation
  • 2006-10-05 EP EP06808234A patent/EP1941222B1/de active Active
  • 2006-10-05 DE DE602006005010T patent/DE602006005010D1/de not_active Expired - Fee Related
  • 2006-10-05 US US12/089,256 patent/US8109446B2/en not_active Expired - Fee Related
  • 2006-10-05 WO PCT/FR2006/002242 patent/WO2007039685A1/fr active Application Filing
  • 2006-10-05 ES ES06808234T patent/ES2318797T3/es active Active

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