WO2001018468A1

WO2001018468A1 - Device for storing and distributing foodstuffs

Info

Publication number: WO2001018468A1
Application number: PCT/NL2000/000608
Authority: WO
Inventors: Lambert Nijmeijer
Original assignee: Foodcorner International B.V.
Priority date: 1999-09-06
Filing date: 2000-09-01
Publication date: 2001-03-15
Also published as: NL1012986C2

Abstract

The invention relates to a device for storing and distributing foodstuffs. The foodstuffs are stored in a cabinet (2) having a cooled chamber (12) which is kept at a constant temperature with the aid of an evaporator (20) and a fan (22) for circulating air through the cabinet (2) and the evaporator (20). According to the invention, the capacity of the fan is such that the air in the cooled chamber is circulated at least three times, and preferably 6 times, per minute.

Description

Device for storing and distributing foodstuffs

The invention relates to a device according to the preamble of claim 1. A device of this type is known, inter alia, from US 5520941. The drawbac of the known device is that when it is switched on the motors of the drives heat up, as a result of which radiation causes the temperature in the cabinet to rise locally, and the foodstuffs are locally heated. As a result, they will temporarily release additional moisture and will therefore dry out to some extent. To avoid this drawback, the device is designed in accordance with the defining clause of claim 1. As a result, local temperature increases caused by the drives being periodically switched on are limited, with the result that the foodstuffs maintain an even temperature and drying out is limited.

According to a refinement, the device is designed according to claim 2. This prevents the evaporator from continuing to cool after the desired temperature of the air stream has been reached.

According to a refinement, the device is designed according to claim 3. This prevents that when the evaporator is being defrosted the contents of the cabinet can warm up.

According to a refinement, the device is designed according to claim 4. This imparts additional turbulence to the air stream in the cabinet, so that the transfer of heat is promoted. According to a refinement, the device is designed according to claim 5. This makes the air velocity less dependent on the frosting of the evaporator.

According to a refinement, the device is designed according to claim 6 or 7. In this way, it is possible to keep the temperature in the cabinet as constant as possible.

According to a refinement, the device is designed according to claim 8. This ensures that energy which is supplied as a result of a turning motor or drive is dissipated immediately and a temperature rise is avoided.

According to a refinement, the device is designed according to claim 9. This makes the temperature distribution through the evaporator more uniform, so that there is less frosting.

According to a refinement, the device is designed according to claim 10. As a result, it is possible to rapidly change the cooling capacity of the evaporator, so that the temperature in the cabinet is stabilised further.

The invention is explained below with reference to an exemplary embodiment. In the drawing: Figure 1 shows a diagrammatic front view of the dispensing system for meat products,

Figure 2 shows a diagrammatic cross section II-II through a cabinet of the dispensing system, Figure 3 diagrammatically depicts the cabinet shown in Figure 2, and

Figure 4 diagrammatically depicts the compression unit belonging to the dispensing system shown in Figure 1.

Figure 1 shows a dispensing system 1 for cooled storage and dispensing of meat products. The dispensing system 1 has two cabinets 2 which are positioned next to one another, in which meat products are stored at a cooled temperature and in which there is a cutting device 10 (cf. Figure 2) for cutting slices from the stored meat products. On each cabinet 2 there is a cooler 5 which is used to cool the contents of the cabinet 2. The coolers 5 are connected, via a line which is not shown, to a compressor unit 3. Each cabinet 2 stores meat products which are visible through a window 6. A purchaser orders a quantity of meat product of a specific type and the ordered number of slices is cut off a piece of stored meat product with the aid of the cutting device 10. The slices are conveyed via a conveying opening 8 to a dispensing unit 4. In the dispensing unit 4, the slices are packaged and released to the purchaser via a dispensing opening 7.

Figure 2 shows a cross section through the cabinet 2. In cabinet 2 there is a cooled chamber 12 which is surrounded by an insulating wall 11, an insulating roof 15 and an insulating door 24. In the cooled chamber 12 there is a storage rack 14 on which shelves bearing meat product 13 are supported. The shelves bearing meat products 13 can be conveyed separately by a conveyor device 27 to the cutting device 10. For this purpose, the conveyor device 27 is provided with a moving shelf carrier 26 and a drive 28. The cutting device 10 has, inter alia, a cutting motor 9. The insulating door 24 is provided with a closeable insertion opening 25 for the removal of empty shelves 13 from the cooled chamber 12 and the insertion of full shelves 13.

The cooler 5 is positioned on top of the insulating roof 15 and is connected to the cooled chamber 12 via openings 16. The cooler 5 comprises an insulating cap 21, an evaporator 20 and a ventilator 22. The ventilator 22 blows a cooled air stream 23 into the cooled chamber 12, and as a result an air stream 17 which is to be cooled leaves the cooled chamber 12 and enters the cooler 5, resulting in an air flow 19 through the evaporator 20. To control the cooler 5, a temperature sensor 48 is positioned in the air stream 17 coming out of the cooled chamber 12 towards the cooler 5.

Foodstuffs which, with a view to shelf life and to allow them to be cut, are kept at a temperature which is as constant as possible, being approximately -2° Celsius, are stored in the cooled chamber 12. Heat is supplied to the cooled chamber 12 from outside the cabinet 2, for example through the walls of the cabinet 2 and in particular through the window 6. This supply of heat is more or less constant and, in the case of a cabinet of a size of 1 by 1 meter with a height of 2 meters, one wall being provided with the window 6, the dissipation of heat required for cooling is approximately 1-1.5 kW. Heat sources, namely the cutting motor 9 and the drive 28, are positioned inside the cooled chamber 12. These heat sources are used for cutting the meat product and mean that the amount of heat to be dissipated may rise to 4 kW.

To ensure that the above mentioned heat sources are sufficiently cooled and the temperature rise in the motors is low, for example at most 5° or 10° Celsius, it is necessary for the air circulation inside the cooled chamber 12 to be high. For this purpose, the fan 22 has a capacity of approximately 800 m³/h, so that the air volume inside the cooled chamber 12 circulates more than three times, and preferably 6 times, per minute.

It has been found that if the cooling is controlled accurately this high circulation of air does not have any adverse effect on the drying out of the foodstuffs.

As a result of this high circulation of air, with an air velocity at the location of the opening 16 which is greater than 0.5 m/sec, and the accurately controlled cooling, the stored meat products remain at a constant temperature, with the result that the loss of moisture and/or the drying out of the meat product remains limited. The moisture which enters the cabinet 2 through the conveyor opening 8 and the introduction opening 25 and the moisture which is released from the meat product despite the constant temperature will freeze on the evaporator 20. To prevent this from rapidly reducing the circulation of air, the fan 22 is designed in such a manner that its capacity is not very dependent on the air resistance, for example by designing the fan 22 as a radial fan.

As a result of the fan 22 being positioned behind the evaporator 20, considerably turbulence is imparted to the air cooled by the evaporator 20 while it is being blown into the cooled chamber 12. As a result, the heat transfer between the air and the objects present in the cooled chamber 12 is optimised. Frosted ice has to be removed from the evaporator 20 several times each day, for example 4 times a day. At these times, the fan 22 is shut down and the evaporator 20 is electrically heated in a manner which is to be described below. Beneath the evaporator 20 there is a leakage tray 18 for collecting and draining water.

As a result of the evaporator 20 being heated, the temperature of the air in the cooler 5 will rise. Since the cooler 5 is separated from the cooled chamber 12 by the insulating roof 15, the products stored therein will not warm up and will maintain an even temperature. Since the cooler 5 is positioned above the cooled chamber 12, the warmer air will not enter the cooled chamber 12 through the openings 16. After defrosting, the evaporator 20 is cooled again, after which the fan 22 is switched on again.

While the evaporator 20 is being defrosted, a process which may last about 10 to 20 minutes, the dispensing of foodstuffs can continue without interruption, since it has been found that the heat developed by the cutting motor 9 and the drive 28 causes only a limited, superficial temperature rise. It is probable that this partly results from the fact that for a temperature rise from -2° Celsius to above the freezing point a phase transfer takes place, which requires considerable amounts of heat.

On account of the above measures, defrosting of the evaporator 20 does not have any adverse effect on the temperature of the foodstuffs which are stored in the cooled chamber 12, and consequently these foodstuffs do not lose any additional moisture or begin to dry. As a result of the temperature in the cooled chamber 12 being kept uniformly below zero, in particular at -2° Celsius, it has proven possible to maintain the atmospheric humidity at above 80-85%, with the result that there is only limited drying. It has been found that in the event of a prolonged shutdown and/or at night, the atmospheric humidity rises to 95% without there being any visible drying. Figure 3 diagrammatically depicts the cooler 5 with the evaporator 20 and fan 22. The evaporator 20 is connected to a condensate supply 29 via a solenoid valve 51. The condensate supplied is passed to the evaporator 20 via a heat exchanger 32 and a control valve 33. In the evaporator 20, the condensate evaporates to form a gas, with the result that the evaporator 20 cools down. The cold gas flows to the heat exchanger 32, where the condensate flowing in is cooled, and then the cold gas flows via a solenoid valve 52 to a gas outlet 30.

The cooler 5 is provided with a control system 50 which is connected to the temperature sensor 48, the solenoid valves 51 and 52 and the control valve 33. When the temperature sensor 48 measures that the air stream 17 is becoming too warm, both quick-switching solenoid valves 51 and 52 are opened, with the result that the condensate flows to the control valve 33. The temperature and pressure of the cold gas flowing out of the evaporator 20 are measured using a sensor 31. The sensor 31 is coupled to the control system 50 which controls the control valve 33 in such a manner that the temperature of the gas flowing out of the evaporator 20 is more or less constant. Since the amount of heat which is to be dissipated from the cooled chamber 12 via the evaporator 20 may vary considerably, the control valve 33 must have a wide control range and must react quickly. It is preferably possible to change the cooling capacity of the evaporator 20 from a minimum level to a maximum level within 10 seconds. For successful operation, it is important that the temperature of the condensate supplied should be more or less constant, fluctuating by no more than 2° Celsius, for example.

To defrost the evaporator 20, the control system 50 is connected to a temperature sensor 49 which is positioned on the evaporator 20, as well as the electrical heater elements (not shown) . After it has been observed that defrosting is required, solenoid valve 51 is closed, with the result that the supply of coolant is stopped, the fan 22 is stopped and the electrical heating is switched on. The temperature sensor 49 measures the temperature of the evaporator 20. After the temperature sensor 49 has observed that the evaporator 20 has been completely defrosted, the solenoid valve 51 is opened again and the fan 22 is started again. Figure 4 diagrammatically depicts the compressor unit 3. The compressor unit 3 shown is coupled to both coolers 5 by means of a gas port 34, which is coupled to the gas outlet 30, and a condensate port 35, which is coupled to the condensate inlet 29. The gas supplied via the gas port 34 is compressed by means of a compressor 44. The compressor 44 is driven by a controllable-speed electric motor 45. The rotational speed of the electric motor 45 is determined by a frequency regulator 46. The frequency regulator 46 is controlled on the basis of the pressure sensor 47, the rotational speed of the compressor 44 is increased at high pressure. In the exemplary embodiment shown, the rotational speed of the compressor 44 can be regulated between 60 and 120%. The compressor 44 is suitable for a low speed and is designed as a piston compressor.

The compressed gas flows via an oil separator 43 to a condenser 39 in which the compressed gas condenses to form a liquid. As a result, heat is generated, this heat being removed by means of a cooling liquid, the temperature and/or pressure of the liquid flowing out the condenser 39 being kept constant, fluctuating by no more than 2° Celsius, for example. The cooling liquid is pumped out of a cooling liquid inlet 41, for example the water mains, by means of a cooling-liquid pump 40, via a control valve 38 through the condenser 39 to a cooling-liquid outlet. The control valve 38 is activated by a temperature and/or pressure sensor 37 which measures the temperature and/or pressure of the condensate flowing out of the condenser 39. The condensate flows to a condensate buffer 36 and, from there, to the condensate port 35. In the device shown, Freon R404A/R507 can be used as the cooling medium. At the temperature and/or pressure sensor 37, this medium is at, for example, a pressure of 14 bar at a temperature of 33° Celsius. This combination of pressure and temperature is dependent on the vapour pressure of the cooling medium. In the cooler 5, the condensate is cooled further by another 3 to 4° Celsius by the heat exchanger 32. Since the output of the compressor 44 is variable, the pressure at the location of the gas port 34 is kept as constant as possible, at 2.5-3 bar. As a result, the pressure in the evaporator 20 is also very constant. This too requires a wide control range of the control valve 33.

In addition to the exemplary embodiment shown, the invention can also be used in devices in which foodstuffs are stored in cooled form and are divided into portions for example by scoops, and are scooped into trays which are to be dispensed. In this situation too, heat is released when the drives are in use, and this heat has to be dissipated rapidly by the cooling system in order to prevent the foodstuffs from drying.

Claims

1. A device for storing and distributing foodstuffs, comprising a cabinet (2) having a cooled chamber (12) which is provided with insulated walls (11,15,24), storage means (14) for storing the foodstuffs, such as pieces of meat product, in the cabinet, drives (9,28) which are positioned in the cabinet (2) for moving and/or cutting the foodstuffs, and cooling means (5) for keeping the foodstuffs at a constant temperature, the cooling means comprising an evaporator (20) having a fan (22) for circulating air through the cabinet and the evaporator (20) , wherein the capacity of the fan (22) is such that the air in the cooled chamber (12) is circulated at least three times, and preferably 6 times, per minute.

2. The device as claimed in claim 1, wherein means (51,52) are provided for simultaneously closing off the inlet and outlet for cooling medium to the evaporator (20).

3. The device as claimed in claim 1 or 2, wherein the evaporator (20) is positioned on the outside and on the cabinet (2) .

4. The device as claimed in claim 1, 2 or 3, wherein the fan (22) sucks the air through the evaporator (20) and blows it into the cabinet (2) .

5. The device as claimed in one of the preceding claims, wherein the fan (22) is a radial fan.

6. The device as claimed in one of the preceding claims, wherein means (37,38) are provided for keeping the temperature of the condensate supplied to the evaporator (20) constant.

7. The device as claimed in claim 6, wherein the means (37,38) for keeping the temperature of the condensate constant limit the maximum temperature differences to 2° Celsius.

8. The device as claimed in one of the preceding claims, wherein the evaporator (20) is provided with means (31,33) for rapidly changing the cooling - in capacity, for example for changing the cooling capacity from its minimum level to its maximum level within 10 seconds .

9. The device as claimed in one of the preceding claims, wherein the evaporator (20) is provided with a heat exchanger (32) for cooling condensate which is supplied.

10. The device as claimed in one of the preceding claims, in which the expanded condensate is compressed by a compressor (44), wherein there are means (45,46,47) for changing the capacity of the compressor as a function of the pressure of the expanded condensate.