US20060124065A9 - Cooling of milk in an automatic milking system - Google Patents
Cooling of milk in an automatic milking system Download PDFInfo
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- US20060124065A9 US20060124065A9 US10/471,172 US47117204A US2006124065A9 US 20060124065 A9 US20060124065 A9 US 20060124065A9 US 47117204 A US47117204 A US 47117204A US 2006124065 A9 US2006124065 A9 US 2006124065A9
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- Prior art keywords
- milk
- cooling
- storage tank
- milk storage
- temperature
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- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01J—MANUFACTURE OF DAIRY PRODUCTS
- A01J9/00—Milk receptacles
- A01J9/04—Milk receptacles with cooling arrangements
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- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01J—MANUFACTURE OF DAIRY PRODUCTS
- A01J5/00—Milking machines or devices
- A01J5/017—Automatic attaching or detaching of clusters
- A01J5/0175—Attaching of clusters
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- 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
- F25B2600/00—Control issues
- F25B2600/02—Compressor control
- F25B2600/025—Compressor control by controlling speed
- F25B2600/0251—Compressor control by controlling speed with on-off operation
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- 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
- F25B2700/19—Pressures
- F25B2700/197—Pressures of the evaporator
Definitions
- the present invention relates generally to dairy farming and particularly to a method and an arrangement, respectively, for cooling of milk in an automatic milking system.
- the milk usually enters the milk storage tank in small amounts spread during the day and night, compared to a dairy farm without an automatic milking system, where all animals are milked together two or three times a day.
- the milk storage tank is usually equipped with a cooling device, which lowers the temperature of the milk to about 4° C. and maintains this temperature in a filled milk storage tank.
- a cooling device which lowers the temperature of the milk to about 4° C. and maintains this temperature in a filled milk storage tank.
- the cooling of milk in a milk storage tank is controlled in response to the temperature of the milk in the tank.
- the milk temperature is usually measured on the outside of the tank due to hygienic requirements, and this results in a rather slow response when the temperature of the milk within the tank is changed.
- Such a sluggish temperature response gives rise to problems, in particular when the volume of stored milk is small.
- the temperature of a small milk volume is lowered rapidly at the risk of freezing the milk.
- the milk storage tank is typically provided with a stirrer, which stirs the milk in the tank to obtain a uniform temperature of the milk.
- a stirrer is usually not able to stir the milk in the tank when the tank contains only small amounts of milk, which thus involves a further risk of freezing milk locally at the beginning of the filling of the tank with milk. If cooling, on the other hand, is omitted while there is only a small volume of milk in the milk storage tank, this milk is not cooled at once, and thus the quality of the milk is deteriorated.
- An object of the present invention is to provide a method and an arrangement, respectively for cooling milk rapidly in an automatic milking system without risk of freezing the milk, particularly when only small amounts of milk are present in the milk storage tank.
- the milk storage tank itself is pre-cooled, i.e. cooled before milk is entered therein.
- milk transported to the milk storage tank can be cooled faster, and thus an enhanced milk quality is obtained.
- the cooling of milk may be performed firstly, when there is only a small volume of milk in the milk storage tank, as set out in the independent claims, and then, when a level of milk in said milk storage tank exceeds a threshold level, the cooling is controlled in response to the temperature of the milk in a conventional fashion.
- FIGS. 1-3 are given by way of illustration only, and thus, are not limitative of the present invention, wherein:
- FIG. 1 is a schematic representation of an automatic milking system including a milk cooling arrangement according to a preferred embodiment of the present invention
- FIG. 2 is an exemplary diagram illustrating the cooling of the inventive milk cooling arrangement of FIG. 1 as a function of time
- FIG. 3 is another exemplary diagram illustrating the cooling of the inventive milk cooling arrangement of FIG. 1 as a function of time.
- An automatic milking system as shown in FIG. 1 , comprises a milking robot 1 for milking animals, such as cows, including a milk flow meter 2 for measuring the milk flow during milking; a milk storage tank 5 which stores milk for collection on a regular time basis; a milk line 4 connecting the milking robot 1 with the milk storage tank 5 ; a milk pump (not shown) for pumping milk from the milking robot 1 to the milk storage tank 5 ; and a pre-cooling device 3 for cooling milk, which is pumped over to the milk storage tank 5 .
- the milk storage tank 5 is provided with a stirrer 6 for stirring milk in the milk storage tank 5 ; and a cooling device 7 for cooling milk in the milk storage tank 5 .
- the cooling device 7 includes typically an evaporator 8 ; a compressor 9 ; a condenser 10 ; and an expansion valve 12 , all of which being interconnected by a connecting piping 13 , such that a cooling medium can be circulated therein.
- the evaporator is suitably integrated in, or in contact with, a bottom portion 14 of the wall of the milk storage tank 5 and the compressor 9 is typically driven by an electrical motor (not shown).
- the cooling device 7 comprises a sensor 15 for sensing a quantity, which is indicative of a temperature of an inner surface area 16 of the bottom portion 14 of the milk storage tank 5 .
- the sensor is preferably a temperature sensor 15 for measuring the temperature of the connecting piping 13 between the expansion valve 12 and the evaporator 8 of the cooling device 7 .
- the temperature sensor 15 may be arranged to measure the temperature of the expansion valve 12 , or of the evaporator 8 .
- the senor may be a pressure sensor (not illustrated) for sensing the pressure in the evaporator 8 or preferably in the connecting piping 13 downstream from the evaporator 8 .
- a temperature sensor is preferred since it is easier to arrange a temperature sensor 15 at the outside of the connecting piping 13 , the expansion valve 12 , or the evaporator 8 than to introduce a pressure sensor within the connecting piping 13 .
- the milking system further comprises a controller 17 , such as a microcomputer provided with suitable software, for controlling and managing the milking robot 1 , including keeping records of animals to be milked and their respective characteristics, such as milk quality, amount of milk per milking, and time lapsed since last milking. Further, the controller 17 is adapted for controlling the cooling device 7 , which includes receiving measured values from the milk flow meter 2 and the sensor 15 .
- a controller 17 such as a microcomputer provided with suitable software, for controlling and managing the milking robot 1 , including keeping records of animals to be milked and their respective characteristics, such as milk quality, amount of milk per milking, and time lapsed since last milking.
- the controller 17 is adapted for controlling the cooling device 7 , which includes receiving measured values from the milk flow meter 2 and the sensor 15 .
- one controller is provided for the control of the milking robot and another separate controller is provided for the control of the cooling device (not illustrated), in which case the two controllers are connected with each other to provide for one-way or two-way communication between them.
- the milk flow in the milking system is measured by the milk flow meter 2 and may be registered by the controller 17 to obtain an accumulated milk flow and optionally to determine the level of milk in the milk storage tank 5 by prior knowledge of the design of the milk storage tank and the obtained accumulated milk flow.
- the level of milk in the milk storage tank may be measured by means of a level-measuring device (not illustrated) located in the milk storage tank 5 .
- the level of milk in the milk storage tank can be determined by measuring a static pressure or change in static pressure of the milk at the bottom of the milk storage tank 5 , e.g. detected by a sensor (not illustrated) at the bottom of the milk storage tank.
- the cooling of the cooling device 7 is controlled, in accordance with the present invention, by operating the cooling device 7 in periods of cooling, each of which being followed by a respective period of non-cooling, where the duration of each period of cooling and/or non-cooling is determined and controlled by the controller 17 . More precisely, the controller 17 is adapted to receive a value of the flow of milk from the milk flow meter 2 ; to determine, i.e. calculate, a cooling need for milk to be stored in said milk storage tank based on the received value of the flow of milk; and to receive a value of the quantity sensed by the sensor 15 . The duration of each period of cooling and/or period of non-cooling is then controlled based on the determined cooling need and the value of the quantity sensed by sensor 15 .
- the cooling of milk in the milk storage tank may be started when only small amounts of milk have been stored therein, and a quick cooling of the first amounts of stored milk is obtained without any risk of freezing the same.
- FIG. 2 is shown a diagram illustrating an example of a the cooling by the cooling device 7 as a function of time, wherein two periods of cooling ⁇ 1 and ⁇ 3 and two periods of non-cooling ⁇ 2 and ⁇ 4 are shown. The duration of two periods of cooling and two periods of non-cooling, at four different times are illustrated in FIG. 2 .
- Such a cooling may occur as a result of the following exemplary scenario.
- a sensor e.g. the milk flow meter 2
- the controller which calculates a new increased cooling need and in response thereto the controller starts the cooling.
- the temperature sensor 15 indicates a low temperature, e.g. close to 0° C., and in response thereto the controller stops the cooling.
- the temperature sensor 15 indicates a higher temperature and in response thereto the controller starts the cooling again.
- the temperature sensor 15 indicates a low temperature and in response thereto the controller stops the cooling.
- the cooling need of the milking system depends on the amount of milk to be stored in the milk storage tank 5 , which in turn is determined by the flow of milk in the milking system.
- the cooling by the cooling device 7 which is required for cooling a specific volume of milk, is divided into periods of cooling and non-cooling to avoid freezing of the milk, and these periods are continued until the cooling need is fulfilled as indicated by the milk flow meter 2 and/or the sensor 15 .
- the accumulated milk flow may be utilized to calculate how much of a heat transfer area, i.e. the area where the cooling device efficiently draws heat from the milk storage tank, in the milk storage tank that is covered by milk. If the milk does not cover the whole heat transfer area, the risk of freezing the milk is particularly large, which may be taken into account by the controller 17 when determining the duration of the periods of cooling and/or the periods of non-cooling.
- the cooling need further depends on the design of the milk storage tank 5 , and of the temperature surrounding the milk storage tank 5 .
- the influence of the surrounding temperature will be less if the milk storage tank is insulated.
- Such insulation is usually implemented as a layer of insulation material between the wall of the milk storage tank and an outer shell.
- cooling device 7 has a minimum period of rest due to the electrical motor of the cooling device having a need to be cool down after a period of cooling, or else the motor might be damaged, such a minimum period of rest defines a minimum duration of a period of non-cooling as controlled by the controller 17 .
- the flow pattern of milk in the milk storage tank 5 i.e. the flow pattern of the milk obtained by inflowing milk and/or obtained by an auxiliary device, such as the stirrer 6 , affects how fast temperature differences of milk in different parts of the milk storage tank are evened out, which might be a factor to consider by the controller 17 .
- a flow pattern obtained by the stirrer 6 has only to be considered when the milk level in milk storage tank has reached the lowermost portion of the stirrer such that stirring really takes place.
- the cooling may be controlled based on the time lapsed since the cooling device 7 ended a period of cooling, the temperature of the milk in the milk storage tank 5 , and the amount of the milk in the milk storage tank 5 . If the controller 17 takes these dependencies into account when determining the lengths of the periods of cooling and non-cooling, a better cooling control may be obtained.
- the first amounts of milk pumped from the milking robot after cleaning the tank may not reach the milk storage tank until several cows have been milked, due to that the milk only fills the inner volume of the milk line 4 . This affects also the cooling need and accordingly the controller 17 may take this into account when controlling the operation of the cooling device 7 .
- the controller may be arranged to initiate a period of cooling when the milk pump of the milking system, at the milking robot, is started, and to control the cooling device based on the number of times the milk pump at the milking robot has been started during a predetermined period of time.
- the controller 17 may be adapted to control the cooling of the cooling device based on the number of animals that have been milked during the predetermined period of time.
- control device 8 keeps record of the cows being milked and identifies each cow prior to milking, such identification may affect the control of the cooling device 7 since a period of cooling may begin earlier or last longer if the cow identified prior to milking is known to have a high milk yield.
- the efficiency of a cooling process using e.g. an air-cooled condenser may change significantly if the temperature surrounding the condenser changes, e.g. depending on the time of year or between daytime and nighttime. That is, a certain amount of electrical effect fed into the cooling device results in one level of cooling during daytime and another level of cooling during nighttime.
- Such environment-dependent cooling capacity could be compensated for by the controller if a temperature sensor is provided for detection of the temperature close to the condenser and using a correction factor depending on this temperature for adjusting the cooling.
- a timer may be used to adjust the correction factor if the temperature variations during the day and night are predictable.
- the pre-cooling device is a heat exchanger, e.g. a plate heat exchanger, it may not be capable to pre-cool a large flow of milk as efficient as a lower flow of milk and thus a larger flow of milk will be warmer when reaching the milk storage tank 5 .
- the controller 17 preferably takes into account the efficiency of the pre-cooling device 3 by means of prior knowledge of its cooling capacity or by means of measuring the temperature of the milk in milk line 4 .
- the milk storage tank itself is pre-cooled, i.e. cooled before milk is entered therein.
- the controller initiates a period of cooling of the milk storage tank 5 itself directly after the cleaning of the same is finished. In such manner, milk transported to the milk storage tank can be cooled faster, and thus an enhanced milk quality can be obtained.
- FIG. 3 illustrates a diagram indicating periods of cooling followed by periods of non-cooling during such pre-cooling of the milk storage tank 5 itself. Firstly five periods of cooling lower the temperature of the milk storage tank to approximately 4° C. by cooling the heat transfer area during each period of cooling to approximately 0° C. During the periods of non-cooling the temperature differences in the milk storage tank wall is equalized.
- the sixth cooling period illustrates the cooling need of a small amount of milk entering, or about to enter, the milk storage tank.
- the seventh cooling period illustrates the cooling need of a large amount or several consecutive small amounts of milk entering, or about to enter, the milk storage tank.
- the cooling need of the tank in this case is 2539 kJ.
- Milk leaving a cow has a temperature of about 37° C., but may have been reduced to about 35° C. during transport to the milk storage tank.
- the cooling device is run in sequences of about one minute followed by a rest period of two minutes (which may be given by the temperature sensed by sensor 15 ), to avoid freezing the milk.
- the controller keeps track of the accumulated milk flow as more cows are being milked and increases the running time when the volume of milk in the tank increases, e.g. to two minutes running time.
- each of the periods of cooling and non-cooling is determined according to an algorithm, which uses at least the determined cooling need and the quantity sensed as inputs. Further inputs may be employed to obtain a refined cooling process. It shall particularly be noted that the duration of each period of non-cooling may not only be determined in response to the quantity sensed, but other measured values or prior knowledge may be used such as e.g. an estimated average number of cows to be milked per time unit.
- the cooling of milk may be performed firstly, when there is only a small volume of milk in the milk storage tank 5 , as described with reference to the first embodiment of the invention, and then, when a level of milk in said milk storage tank exceeds a threshold level, the cooling is controlled in a conventional fashion, i.e. in response to a temperature of milk in the milk storage tank 5 .
- the threshold value is preferably determined to be a level, which is sufficiently high so the stirrer 6 can effectively stir the milk in the milk storage tank 5 and even out any temperature gradients in the milk. Thus the risk of freezing the milk is very low.
- the controller 17 may use a feedback process for adjusting the periods of cooling and/or periods of non-cooling.
- a temperature of the milk at the end of a cooling process e.g. a cooling process, which ends when the milk in the milk storage tank 5 is collected, or alternatively when the milk level in the milk storage tank exceeds the above-mentioned threshold value
- the controller may adjust the cooling capacity of the cooling device 7 accordingly for a following cooling process. Such an adjustment may be made by introducing a correction factor to correct for the discrepancy between the detected and the expected temperatures.
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Abstract
Description
- The present invention relates generally to dairy farming and particularly to a method and an arrangement, respectively, for cooling of milk in an automatic milking system.
- In dairy farming animals are milked and their milk is thereafter stored in a milk storage tank for collection on a regular time basis, e.g. every second day. In order to maintain the quality of the milk, it is cooled to approximately 4° C. as quickly as possible. It is necessary to be careful during cooling of the milk since the quality is deteriorated if the milk freezes.
- At a dairy farm provided with an automatic milking system, the milk usually enters the milk storage tank in small amounts spread during the day and night, compared to a dairy farm without an automatic milking system, where all animals are milked together two or three times a day. The milk storage tank is usually equipped with a cooling device, which lowers the temperature of the milk to about 4° C. and maintains this temperature in a filled milk storage tank. When the milk storage tank only contains small amounts of milk, there is a considerable risk of cooling the milk too much since the cooling device, when cooling, operates at full capacity.
- Usually the cooling of milk in a milk storage tank is controlled in response to the temperature of the milk in the tank. The milk temperature is usually measured on the outside of the tank due to hygienic requirements, and this results in a rather slow response when the temperature of the milk within the tank is changed. Such a sluggish temperature response gives rise to problems, in particular when the volume of stored milk is small. The temperature of a small milk volume is lowered rapidly at the risk of freezing the milk.
- Furthermore, the milk storage tank is typically provided with a stirrer, which stirs the milk in the tank to obtain a uniform temperature of the milk. Such a stirrer is usually not able to stir the milk in the tank when the tank contains only small amounts of milk, which thus involves a further risk of freezing milk locally at the beginning of the filling of the tank with milk. If cooling, on the other hand, is omitted while there is only a small volume of milk in the milk storage tank, this milk is not cooled at once, and thus the quality of the milk is deteriorated.
- An object of the present invention is to provide a method and an arrangement, respectively for cooling milk rapidly in an automatic milking system without risk of freezing the milk, particularly when only small amounts of milk are present in the milk storage tank.
- This object, among others, is attained by methods and arrangements, respectively, as claimed in the appended patent claims.
- By cooling in consecutive periods according to the present invention, milk is cooled without risk of being frozen, and thus a high milk quality can be safeguarded.
- In accordance with one preferred embodiment of the present invention the milk storage tank itself is pre-cooled, i.e. cooled before milk is entered therein. In such manner, milk transported to the milk storage tank can be cooled faster, and thus an enhanced milk quality is obtained.
- In accordance with another preferred embodiment of the present invention the cooling of milk may be performed firstly, when there is only a small volume of milk in the milk storage tank, as set out in the independent claims, and then, when a level of milk in said milk storage tank exceeds a threshold level, the cooling is controlled in response to the temperature of the milk in a conventional fashion.
- Further features and advantages of the present invention will be evident from the following description.
- The present invention will become better understood from the detailed description of embodiments given below and the accompanying
FIGS. 1-3 , which are given by way of illustration only, and thus, are not limitative of the present invention, wherein: -
FIG. 1 is a schematic representation of an automatic milking system including a milk cooling arrangement according to a preferred embodiment of the present invention; -
FIG. 2 is an exemplary diagram illustrating the cooling of the inventive milk cooling arrangement ofFIG. 1 as a function of time; and -
FIG. 3 is another exemplary diagram illustrating the cooling of the inventive milk cooling arrangement ofFIG. 1 as a function of time. - In the following description, for purpose of explanation and not limitation, specific details are set forth, such as particular techniques and applications in order to provide a thorough understanding of the present invention. However, it will be apparent for a person skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details.
- An automatic milking system, as shown in
FIG. 1 , comprises amilking robot 1 for milking animals, such as cows, including amilk flow meter 2 for measuring the milk flow during milking; amilk storage tank 5 which stores milk for collection on a regular time basis; amilk line 4 connecting themilking robot 1 with themilk storage tank 5; a milk pump (not shown) for pumping milk from themilking robot 1 to themilk storage tank 5; and a pre-cooling device 3 for cooling milk, which is pumped over to themilk storage tank 5. - The
milk storage tank 5 is provided with astirrer 6 for stirring milk in themilk storage tank 5; and acooling device 7 for cooling milk in themilk storage tank 5. - The
cooling device 7 includes typically anevaporator 8; acompressor 9; acondenser 10; and anexpansion valve 12, all of which being interconnected by a connectingpiping 13, such that a cooling medium can be circulated therein. The evaporator is suitably integrated in, or in contact with, abottom portion 14 of the wall of themilk storage tank 5 and thecompressor 9 is typically driven by an electrical motor (not shown). - Furthermore, the
cooling device 7 comprises asensor 15 for sensing a quantity, which is indicative of a temperature of aninner surface area 16 of thebottom portion 14 of themilk storage tank 5. - The sensor is preferably a
temperature sensor 15 for measuring the temperature of the connectingpiping 13 between theexpansion valve 12 and theevaporator 8 of thecooling device 7. - Alternatively, the
temperature sensor 15 may be arranged to measure the temperature of theexpansion valve 12, or of theevaporator 8. - As a further alternative, the sensor may be a pressure sensor (not illustrated) for sensing the pressure in the
evaporator 8 or preferably in the connectingpiping 13 downstream from theevaporator 8. However, a temperature sensor is preferred since it is easier to arrange atemperature sensor 15 at the outside of the connectingpiping 13, theexpansion valve 12, or theevaporator 8 than to introduce a pressure sensor within the connectingpiping 13. - The milking system further comprises a
controller 17, such as a microcomputer provided with suitable software, for controlling and managing themilking robot 1, including keeping records of animals to be milked and their respective characteristics, such as milk quality, amount of milk per milking, and time lapsed since last milking. Further, thecontroller 17 is adapted for controlling thecooling device 7, which includes receiving measured values from themilk flow meter 2 and thesensor 15. - Alternatively, one controller is provided for the control of the milking robot and another separate controller is provided for the control of the cooling device (not illustrated), in which case the two controllers are connected with each other to provide for one-way or two-way communication between them.
- The milk flow in the milking system is measured by the
milk flow meter 2 and may be registered by thecontroller 17 to obtain an accumulated milk flow and optionally to determine the level of milk in themilk storage tank 5 by prior knowledge of the design of the milk storage tank and the obtained accumulated milk flow. - Alternatively, the level of milk in the milk storage tank may be measured by means of a level-measuring device (not illustrated) located in the
milk storage tank 5. - As a further alternative, the level of milk in the milk storage tank can be determined by measuring a static pressure or change in static pressure of the milk at the bottom of the
milk storage tank 5, e.g. detected by a sensor (not illustrated) at the bottom of the milk storage tank. - Instead of measuring the milk flow in the
robot 1 it would be possible to provide a milk flow meter (not illustrated) in themilk line 4, e.g. adjacent to themilk storage tank 5, to measure the milk flow there. - The cooling of the
cooling device 7 is controlled, in accordance with the present invention, by operating thecooling device 7 in periods of cooling, each of which being followed by a respective period of non-cooling, where the duration of each period of cooling and/or non-cooling is determined and controlled by thecontroller 17. More precisely, thecontroller 17 is adapted to receive a value of the flow of milk from themilk flow meter 2; to determine, i.e. calculate, a cooling need for milk to be stored in said milk storage tank based on the received value of the flow of milk; and to receive a value of the quantity sensed by thesensor 15. The duration of each period of cooling and/or period of non-cooling is then controlled based on the determined cooling need and the value of the quantity sensed bysensor 15. - It is particularly important to control the cooling such that the temperature of the
inner surface area 16 of thebottom portion 14 of themilk storage tank 5 does not fall below 0° C. - By such an approach the cooling of milk in the milk storage tank may be started when only small amounts of milk have been stored therein, and a quick cooling of the first amounts of stored milk is obtained without any risk of freezing the same.
- In
FIG. 2 is shown a diagram illustrating an example of a the cooling by thecooling device 7 as a function of time, wherein two periods of cooling τ1 and τ3 and two periods of non-cooling τ2 and τ4 are shown. The duration of two periods of cooling and two periods of non-cooling, at four different times are illustrated inFIG. 2 . - Such a cooling may occur as a result of the following exemplary scenario. At t1 a sensor, e.g. the
milk flow meter 2, indicates an increased milk flow to the controller, which calculates a new increased cooling need and in response thereto the controller starts the cooling. At t2 thetemperature sensor 15 indicates a low temperature, e.g. close to 0° C., and in response thereto the controller stops the cooling. At t3 thetemperature sensor 15 indicates a higher temperature and in response thereto the controller starts the cooling again. Then, at t4 thetemperature sensor 15 indicates a low temperature and in response thereto the controller stops the cooling. - The cooling need of the milking system depends on the amount of milk to be stored in the
milk storage tank 5, which in turn is determined by the flow of milk in the milking system. The cooling by thecooling device 7, which is required for cooling a specific volume of milk, is divided into periods of cooling and non-cooling to avoid freezing of the milk, and these periods are continued until the cooling need is fulfilled as indicated by themilk flow meter 2 and/or thesensor 15. - The accumulated milk flow may be utilized to calculate how much of a heat transfer area, i.e. the area where the cooling device efficiently draws heat from the milk storage tank, in the milk storage tank that is covered by milk. If the milk does not cover the whole heat transfer area, the risk of freezing the milk is particularly large, which may be taken into account by the
controller 17 when determining the duration of the periods of cooling and/or the periods of non-cooling. - The cooling need further depends on the design of the
milk storage tank 5, and of the temperature surrounding themilk storage tank 5. The influence of the surrounding temperature will be less if the milk storage tank is insulated. Such insulation is usually implemented as a layer of insulation material between the wall of the milk storage tank and an outer shell. - If the
cooling device 7 has a minimum period of rest due to the electrical motor of the cooling device having a need to be cool down after a period of cooling, or else the motor might be damaged, such a minimum period of rest defines a minimum duration of a period of non-cooling as controlled by thecontroller 17. - The flow pattern of milk in the
milk storage tank 5, i.e. the flow pattern of the milk obtained by inflowing milk and/or obtained by an auxiliary device, such as thestirrer 6, affects how fast temperature differences of milk in different parts of the milk storage tank are evened out, which might be a factor to consider by thecontroller 17. A flow pattern obtained by thestirrer 6 has only to be considered when the milk level in milk storage tank has reached the lowermost portion of the stirrer such that stirring really takes place. - Furthermore, there are a number of more operation conditions, which, more or less, may affect the cooling need, the cooling capacity, or which may be utilized to correct the cooling as performed by the
cooling device 7 and controlled by thecontroller 17. - The cooling may be controlled based on the time lapsed since the
cooling device 7 ended a period of cooling, the temperature of the milk in themilk storage tank 5, and the amount of the milk in themilk storage tank 5. If thecontroller 17 takes these dependencies into account when determining the lengths of the periods of cooling and non-cooling, a better cooling control may be obtained. - In some designs of a milking system the first amounts of milk pumped from the milking robot after cleaning the tank may not reach the milk storage tank until several cows have been milked, due to that the milk only fills the inner volume of the
milk line 4. This affects also the cooling need and accordingly thecontroller 17 may take this into account when controlling the operation of thecooling device 7. - The controller may be arranged to initiate a period of cooling when the milk pump of the milking system, at the milking robot, is started, and to control the cooling device based on the number of times the milk pump at the milking robot has been started during a predetermined period of time.
- Alternatively, or as complement, the
controller 17 may be adapted to control the cooling of the cooling device based on the number of animals that have been milked during the predetermined period of time. - As the
control device 8 keeps record of the cows being milked and identifies each cow prior to milking, such identification may affect the control of thecooling device 7 since a period of cooling may begin earlier or last longer if the cow identified prior to milking is known to have a high milk yield. - The efficiency of a cooling process using e.g. an air-cooled condenser may change significantly if the temperature surrounding the condenser changes, e.g. depending on the time of year or between daytime and nighttime. That is, a certain amount of electrical effect fed into the cooling device results in one level of cooling during daytime and another level of cooling during nighttime. Such environment-dependent cooling capacity could be compensated for by the controller if a temperature sensor is provided for detection of the temperature close to the condenser and using a correction factor depending on this temperature for adjusting the cooling. Alternatively, a timer may be used to adjust the correction factor if the temperature variations during the day and night are predictable.
- Further, if the pre-cooling device is a heat exchanger, e.g. a plate heat exchanger, it may not be capable to pre-cool a large flow of milk as efficient as a lower flow of milk and thus a larger flow of milk will be warmer when reaching the
milk storage tank 5. Thus, thecontroller 17 preferably takes into account the efficiency of the pre-cooling device 3 by means of prior knowledge of its cooling capacity or by means of measuring the temperature of the milk inmilk line 4. - In a particular embodiment of the present invention the milk storage tank itself is pre-cooled, i.e. cooled before milk is entered therein. Preferably, the controller initiates a period of cooling of the
milk storage tank 5 itself directly after the cleaning of the same is finished. In such manner, milk transported to the milk storage tank can be cooled faster, and thus an enhanced milk quality can be obtained. -
FIG. 3 illustrates a diagram indicating periods of cooling followed by periods of non-cooling during such pre-cooling of themilk storage tank 5 itself. Firstly five periods of cooling lower the temperature of the milk storage tank to approximately 4° C. by cooling the heat transfer area during each period of cooling to approximately 0° C. During the periods of non-cooling the temperature differences in the milk storage tank wall is equalized. The sixth cooling period illustrates the cooling need of a small amount of milk entering, or about to enter, the milk storage tank. The seventh cooling period illustrates the cooling need of a large amount or several consecutive small amounts of milk entering, or about to enter, the milk storage tank. - Next an example of cooling of a 3500-liter milk storage tank having a wall made of 300 kg stainless steel will be described.
- Subsequent to cleaning, the tank has a temperature of about 20° C. and then 2400 kJ of cooling capacity is needed to bring the tank temperature down to 4° C. according to the formula E=cmΔt, where c is the heat capacity, m is the mass of the tank and Δt is the temperature drop caused by cooling (c=500 J/kg° C. for stainless steel, m=300 kg, and Δt=16° C.). Any heat losses to the air surrounding the tank are assumed to be negligible in this calculation.
- Such a milk storage tank contains about 4 kg of air, which needs 65 kJ of cooling capacity to bring the air temperature down to 4° C., since cp=1000 J/kg° C. for air. Further, 0.06 kg of moisture in the air will be reduced to 0.03 kg during the cooling process, which consumes 74 kJ of condensation energy.
- Thus, it can be seen that the cooling need of the tank in this case is 2539 kJ. A 3 kW cooling compressor having a cooling factor of ε=2.4 needs a running time of about six minutes to produce the cooling capacity needed to bring the temperature of the milk storage tank down to 4° C. (according to running time τ=E/Pε, where the energy E is 2539 kJ, the power P is 3 kW, and the cooling factor ε is 2.4).
- Since the heat transfer between the bottom wall of the empty milk storage tank and the side walls thereof takes place during a period of time, it may be advisable to start the cooling compressor subsequent to the cleaning and let it run for two minutes to get an initial lowering of the temperature at the bottom of the tank. Thereafter a period of rest of about two minutes is used (which may be given by the temperature sensed by sensor 15) to equalize the temperature in the tank. Two minutes running period and two minutes rest period can then be repeated (given by the temperature sensed by sensor 15) until a complete running time of the six minutes is achieved.
- Milk leaving a cow has a temperature of about 37° C., but may have been reduced to about 35° C. during transport to the milk storage tank. An amount of 15 l of milk needs an effective compressor running time of about 270 s, as m≈15 kg, Δt=31° C., c=4190 J/kg° C. for milk, P=3000 W, and ε=2.4.
- As the milk from the first cow only covers a part of the cooling surface in the milk storage tank, the cooling device is run in sequences of about one minute followed by a rest period of two minutes (which may be given by the temperature sensed by sensor 15), to avoid freezing the milk. The controller keeps track of the accumulated milk flow as more cows are being milked and increases the running time when the volume of milk in the tank increases, e.g. to two minutes running time.
- It shall be appreciated that the duration of each of the periods of cooling and non-cooling is determined according to an algorithm, which uses at least the determined cooling need and the quantity sensed as inputs. Further inputs may be employed to obtain a refined cooling process. It shall particularly be noted that the duration of each period of non-cooling may not only be determined in response to the quantity sensed, but other measured values or prior knowledge may be used such as e.g. an estimated average number of cows to be milked per time unit.
- In yet a particular embodiment of the present invention the cooling of milk may be performed firstly, when there is only a small volume of milk in the
milk storage tank 5, as described with reference to the first embodiment of the invention, and then, when a level of milk in said milk storage tank exceeds a threshold level, the cooling is controlled in a conventional fashion, i.e. in response to a temperature of milk in themilk storage tank 5. The threshold value is preferably determined to be a level, which is sufficiently high so thestirrer 6 can effectively stir the milk in themilk storage tank 5 and even out any temperature gradients in the milk. Thus the risk of freezing the milk is very low. - In still a particular embodiment of the present invention the
controller 17 may use a feedback process for adjusting the periods of cooling and/or periods of non-cooling. Thus, if a temperature of the milk at the end of a cooling process (e.g. a cooling process, which ends when the milk in themilk storage tank 5 is collected, or alternatively when the milk level in the milk storage tank exceeds the above-mentioned threshold value) is detected to be different than expected (e.g. different than an end temperature used in the calculation of the cooling need), the controller may adjust the cooling capacity of thecooling device 7 accordingly for a following cooling process. Such an adjustment may be made by introducing a correction factor to correct for the discrepancy between the detected and the expected temperatures. - The present invention being thus described, it will be obvious that the same may be varied in a plurality of ways. All such variations as would be obvious for a person skilled in the art are intended to be included within the scope of the present invention.
Claims (23)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/471,172 US7089880B2 (en) | 2000-02-04 | 2002-03-19 | Cooling milk in an automatic milking system |
Applications Claiming Priority (8)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE0000362A SE0000362D0 (en) | 2000-02-04 | 2000-02-04 | Method and system for controlled cooling of small milk quantities |
SE0000362-4 | 2000-02-04 | ||
PCT/SE2001/000192 WO2001056370A1 (en) | 2000-02-04 | 2001-02-01 | Method and system for controlled cooling of small milk quantities |
SE0100970-3 | 2001-03-20 | ||
SE0100970A SE523119C2 (en) | 2001-03-20 | 2001-03-20 | Method and apparatus for cooling milk in an automatic milking system |
PCT/SE2002/000522 WO2002074069A1 (en) | 2001-03-20 | 2002-03-19 | Cooling of milk in an automatic milking system |
US10/471,172 US7089880B2 (en) | 2000-02-04 | 2002-03-19 | Cooling milk in an automatic milking system |
US10/183,000 US6782705B2 (en) | 2000-02-04 | 2002-11-25 | Method and system for controlled cooling of small milk quantities |
Related Parent Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/SE2001/000192 Continuation-In-Part WO2001056370A1 (en) | 2000-02-04 | 2001-02-01 | Method and system for controlled cooling of small milk quantities |
US10/183,000 Continuation-In-Part US6782705B2 (en) | 2000-02-04 | 2002-11-25 | Method and system for controlled cooling of small milk quantities |
Publications (3)
Publication Number | Publication Date |
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US20040129227A1 US20040129227A1 (en) | 2004-07-08 |
US20060124065A9 true US20060124065A9 (en) | 2006-06-15 |
US7089880B2 US7089880B2 (en) | 2006-08-15 |
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Application Number | Title | Priority Date | Filing Date |
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US10/471,172 Expired - Lifetime US7089880B2 (en) | 2000-02-04 | 2002-03-19 | Cooling milk in an automatic milking system |
Country Status (9)
Country | Link |
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US (1) | US7089880B2 (en) |
EP (1) | EP1370131B1 (en) |
AT (1) | ATE330462T1 (en) |
CA (1) | CA2442277C (en) |
DE (1) | DE60212586T2 (en) |
DK (1) | DK1370131T3 (en) |
IL (2) | IL157973A0 (en) |
SE (1) | SE523119C2 (en) |
WO (1) | WO2002074069A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20170150695A1 (en) * | 2014-05-20 | 2017-06-01 | Delaval Holding Ab | System for storing and cooling milk, milking system, and method for cooling milk |
US11229186B2 (en) | 2016-12-16 | 2022-01-25 | Delaval Holding Ab | Method and apparatus for cooling of milk |
Families Citing this family (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL1023341C2 (en) * | 2003-05-05 | 2004-11-09 | Lely Entpr Ag | Device for milking an animal with a milk tank. |
DE10337264A1 (en) * | 2003-08-13 | 2005-03-10 | Westfaliasurge Gmbh | Method for providing data for a control system for a milking arrangement of a milking system and method for cooling milk in a milk cooling arrangement and control system for a milk cooling arrangement |
RU2551565C2 (en) | 2010-01-29 | 2015-05-27 | Геа Хоул Инк. | Rotary milking station, kit for its mounting and methods of its mounting and operation |
GB201022113D0 (en) | 2010-12-30 | 2011-02-02 | Delaval Internat Ab | Bulk fluid refrigeration and heating |
GB2497987A (en) * | 2011-12-23 | 2013-07-03 | Delaval Internat Ab | Bulk fluid refrigeration and heating apparatus |
BE1020437A3 (en) * | 2012-05-23 | 2013-10-01 | Packo Inox Nv | COOLING DEVICE AND METHOD FOR COOLING A LIQUID WITH SUCH A COOLING DEVICE |
SE537535C2 (en) * | 2013-10-07 | 2015-06-02 | Delaval Holding Ab | Milk cooling tank and Milk cooling method |
ES2680823T3 (en) | 2014-08-11 | 2018-09-11 | Delaval Holding Ab | Cooling system to cool a milk flow, milk storage facility, milking system, and method to reconfigure a cooling system |
RU168785U1 (en) * | 2016-08-17 | 2017-02-20 | Лазарь Ефимович Бродский | MILK INSTANT COOLING COMPLEX WITH ICE BATTERY |
SE2030317A1 (en) * | 2020-10-22 | 2022-04-23 | Wedholms Ab | Procedure and arrangement for heat exchange |
US20240032499A1 (en) * | 2020-12-21 | 2024-02-01 | Delaval Holding Ab | Milk-flow control unit, computer-implemented method for controlling a flow of milk, computer program and non-volatile data carrier |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2509214A (en) * | 1944-03-20 | 1950-05-30 | Cordis Nat | Milking apparatus |
USRE23543E (en) * | 1952-09-02 | Milking system and apparatus | ||
US4612537A (en) * | 1985-01-28 | 1986-09-16 | Maritonex Inc. | Alarm system for monitoring the temperature of a liquid contained in a reservoir |
US5275124A (en) * | 1989-02-27 | 1994-01-04 | C. Van Der Lely N.V. | Milking apparatus |
US5769025A (en) * | 1993-01-26 | 1998-06-23 | Maasland, N.V. | Milking apparatus |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2665824B1 (en) * | 1990-08-14 | 1993-09-17 | Prominox Sa | METHOD AND SYSTEM FOR STORING AND PRESERVING BULK MILK IN A TANK. |
DE29723985U1 (en) | 1996-03-29 | 1999-07-08 | Maasland N.V., Maasland | Device for milking animals |
SE0000362D0 (en) * | 2000-02-04 | 2000-02-04 | Alfa Laval Agri Ab | Method and system for controlled cooling of small milk quantities |
-
2001
- 2001-03-20 SE SE0100970A patent/SE523119C2/en unknown
-
2002
- 2002-03-19 CA CA002442277A patent/CA2442277C/en not_active Expired - Lifetime
- 2002-03-19 US US10/471,172 patent/US7089880B2/en not_active Expired - Lifetime
- 2002-03-19 DE DE60212586T patent/DE60212586T2/en not_active Expired - Lifetime
- 2002-03-19 WO PCT/SE2002/000522 patent/WO2002074069A1/en active IP Right Grant
- 2002-03-19 EP EP02708883A patent/EP1370131B1/en not_active Expired - Lifetime
- 2002-03-19 IL IL15797302A patent/IL157973A0/en active IP Right Grant
- 2002-03-19 DK DK02708883T patent/DK1370131T3/en active
- 2002-03-19 AT AT02708883T patent/ATE330462T1/en not_active IP Right Cessation
-
2003
- 2003-09-17 IL IL157973A patent/IL157973A/en not_active IP Right Cessation
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
USRE23543E (en) * | 1952-09-02 | Milking system and apparatus | ||
US2509214A (en) * | 1944-03-20 | 1950-05-30 | Cordis Nat | Milking apparatus |
US4612537A (en) * | 1985-01-28 | 1986-09-16 | Maritonex Inc. | Alarm system for monitoring the temperature of a liquid contained in a reservoir |
US5275124A (en) * | 1989-02-27 | 1994-01-04 | C. Van Der Lely N.V. | Milking apparatus |
US5769025A (en) * | 1993-01-26 | 1998-06-23 | Maasland, N.V. | Milking apparatus |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20170150695A1 (en) * | 2014-05-20 | 2017-06-01 | Delaval Holding Ab | System for storing and cooling milk, milking system, and method for cooling milk |
US10537088B2 (en) * | 2014-05-20 | 2020-01-21 | Delaval Holding Ab | System for storing and cooling milk, milking system, and method for cooling milk |
US11229186B2 (en) | 2016-12-16 | 2022-01-25 | Delaval Holding Ab | Method and apparatus for cooling of milk |
Also Published As
Publication number | Publication date |
---|---|
EP1370131A1 (en) | 2003-12-17 |
DE60212586T2 (en) | 2007-06-28 |
ATE330462T1 (en) | 2006-07-15 |
IL157973A0 (en) | 2004-03-28 |
DE60212586D1 (en) | 2006-08-03 |
CA2442277A1 (en) | 2002-09-26 |
SE523119C2 (en) | 2004-03-30 |
IL157973A (en) | 2008-08-07 |
US20040129227A1 (en) | 2004-07-08 |
WO2002074069A1 (en) | 2002-09-26 |
EP1370131B1 (en) | 2006-06-21 |
SE0100970L (en) | 2002-09-21 |
US7089880B2 (en) | 2006-08-15 |
DK1370131T3 (en) | 2006-10-23 |
SE0100970D0 (en) | 2001-03-20 |
CA2442277C (en) | 2010-03-02 |
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