Freezing device

Abstract

To reduce refrigerant consumption while enabling more efficient cooling. [Solution] In a freezing apparatus 11 equipped with a freezing chamber 12 having an exhaust port 15 and using liquefied gas as a refrigerant, a cooling plate 16 is provided on the inner bottom surface 12a of the freezing chamber 12 on which the object to be frozen is placed directly or indirectly. The cooling plate 16 is made of metal and has a built-in refrigerant flow path 16a. Liquid refrigerant is supplied to the inlet 16b of the refrigerant flow path 16a, while gaseous refrigerant is released from the outlet of the refrigerant flow path 16a to fill the freezing chamber 12 and perform the freezing process.

Description

Technical Field

[0001] The present invention relates to a freezing device suitable for freezing biological materials such as cells and tissues in fields such as regenerative medicine and biotechnology.

Background Art

[0002] The freezing of cells is performed at a uniform cooling rate to prevent damage to the cells. For this freezing, there are those that use a liquefied gas such as liquid nitrogen and those that use a Stirling refrigerator driven by electricity. Although both of these have advantages and disadvantages, the Stirling refrigerator that performs local cooling is characterized by being small and highly efficient, and has a drawback in terms of its mechanism that its capacity is limited compared to those that use liquid nitrogen. Therefore, it is not suitable for freezing a large amount of biological materials at once. Furthermore, there is a limit to the freezing speed, and freezing at a speed exceeding the general 1 °C / min cannot be achieved, and it may not be possible to cope with freezing depending on the type of cells.

[0003] As a freezing device that uses a liquefied gas such as liquid nitrogen as a refrigerant, a cell freezing device is disclosed in Patent Document 1 below. This freezing device has a configuration in which a liquefied gas refrigerant is passed through a cooling block on which the object to be frozen is placed for cooling, while the liquefied gas refrigerant is introduced into a cooling chamber for cooling.

[0004] With such a configuration, it is possible to increase the size, and there is no limit to the cooling speed. However, since the refrigerant flowing into the cooling block is discharged from the refrigerant outlet, the consumption of the refrigerant becomes large.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The main objective of this invention is to enable more effective cooling while reducing refrigerant consumption. [Means for solving the problem]

[0007] Therefore, the freezing apparatus provided by this invention has the following configuration. Specifically, in a freezing apparatus equipped with a freezing chamber having an exhaust port and using liquefied gas as a refrigerant, a metal cooling plate equipped with a refrigerant flow path is provided in the freezing chamber, liquid refrigerant is supplied to the inlet of the refrigerant flow path, and gaseous refrigerant is released into the freezing chamber from the outlet of the refrigerant flow path.

[0008] In this configuration, the cooling plate, cooled within the freezing chamber by liquid refrigerant supplied through the refrigerant flow path, cools the object to be frozen indirectly or directly. Simultaneously, the gaseous refrigerant released from the cooling plate diffuses into the freezing chamber, cooling the entire chamber. Furthermore, the gaseous refrigerant expels the air inside the freezing chamber through the exhaust port, preventing condensation of moisture. [Effects of the Invention]

[0009] According to this invention, a liquid refrigerant is supplied to a cooling plate close to the object to be frozen, and gaseous refrigerant is released from the cooling plate. This configuration allows for simultaneous cooling by the cooling plate and by the gaseous refrigerant in the freezing chamber. As a result, uniform and even cooling is possible. Furthermore, the refrigerant supplied to the cooling plate is not discharged but used to cool the freezing chamber, thus reducing refrigerant consumption while cooling the entire freezing chamber. Moreover, since the air in the freezing chamber can be purged with gaseous refrigerant, uniform cooling is possible, resulting in more appropriate freezing. In this way, a freezing device that takes advantage of the benefits of refrigerants such as liquid nitrogen, which have high cooling capacity and a wide temperature control range, can be provided. [Brief explanation of the drawing]

[0010] [Figure 1] A cross-sectional view showing the schematic structure of a freezing device. [Figure 2] An explanatory diagram showing the action. [Modes for carrying out the invention]

[0011] One embodiment for carrying out this invention will be described below with reference to the drawings.

[0012] Figure 1 shows a schematic cross-sectional view of the freezing apparatus 11. This freezing apparatus 11 is a programmable freezer suitable for freezing biological materials such as cells, and uses cryogenic liquefied gas as a refrigerant. In other words, the amount of refrigerant supplied is adjusted by an automatic valve according to the freezing program, and freezing is performed while controlling the cooling rate of the object to be frozen.

[0013] The freezing chamber 12, where cooling takes place, is located within a heat-insulating enclosure 13 and has a single-leaf door 14 for inserting and removing objects to be frozen, and an exhaust port 15 for discharging gas from inside the freezing chamber 12. In the illustrated example of the freezing device 11, the door 14 is located on the front of the enclosure 13. The exhaust port 15 is located on one of the walls in the left-right direction when viewed from the front of the door 14, and is connected to an exhaust passage (not shown) that leads to the outside.

[0014] A cooling plate 16 is provided on the inner bottom surface 12a of the freezing chamber 12, which is cooled by introducing a refrigerant. The cooling plate 16 is a thick plate made of a metal material with good thermal conductivity, such as aluminum alloy, stainless steel alloy, or copper, and has a refrigerant flow path 16a inside. The cooling plate 16 has a rectangular or square shape in plan view, and its top and bottom surfaces are flat. The refrigerant flow path 16a has an inlet 16b and an outlet 16c on one of the four end faces of the cooling plate 16, and the portion between the inlet 16b and the outlet 16c is meandering and widens in the planar direction to enable uniform cooling. The inlet 16b is the part into which liquid refrigerant is introduced, and the outlet 16c is the part into which gaseous refrigerant, which has changed state as the liquid refrigerant vaporizes during flow, is released. The outlet 16c may simply be open, but it may also be equipped with a nozzle (not shown) for atomization. A temperature sensor 17 is provided on the upper side of the thickness of the cooling plate 16. The temperature sensor 17 can be constructed using a thermocouple.

[0015] Below the cooling plate 16, a heater plate 18 is provided in a state where the entire surfaces of the opposing surfaces of the heater plate 18 are in contact with each other (see Figure 2). The heater plate 18 is a thick plate made of a metal material with good thermal conductivity, similar to the cooling plate 16, and is configured to incorporate a heater 18a, for example, a cartridge heater.

[0016] These cooling plates 16 and heater plates 18 may be formed as a single unit. In other words, a cooling layer having a refrigerant flow path 16a may be formed on the upper side in the thickness direction of a thick metal plate, and a heating layer equipped with a heater 18a may be formed on the lower side.

[0017] The heater plate 18, to which the cooling plate 16 is attached, is supported in a raised state by a synthetic resin positioning plate 19 provided on the inner bottom surface 12a of the freezing chamber 12, making it less susceptible to external disturbances. In this support, the cooling plate 16 is positioned so that its inlet 16b and outlet 16c are oriented away from the side of the freezing chamber 12 where the exhaust port 15 is located.

[0018] A refrigerant gas supply unit 21 is provided on the inner wall of the freezing chamber 12 opposite the exhaust port 15, that is, on the inner surface where the inlet 16b and outlet 16c face each other, to supply gaseous refrigerant to the freezing chamber 12. The refrigerant gas supply unit 21 consists of a nozzle that atomizes liquid refrigerant. A fan 22 is provided further ahead of the refrigerant gas supply unit 21, that is, at a position corresponding to the space between the refrigerant gas supply unit 21 and the cooling plate 16 in a plan view. The fan 22 rotates to agitate the gas inside the freezing chamber 12 and send it toward the exhaust port 15.

[0019] Furthermore, a temperature sensor 23 is provided inside the freezing chamber 12. The temperature sensor 23 measures the temperature inside the freezing chamber 12, that is, the temperature of the atmosphere filling the freezing chamber 12, and can be made up of, for example, a thermocouple.

[0020] On the surface of the outer shell 13 opposite to the surface where the exhaust port 15 is provided, there are provided a flow path 31 for introducing the refrigerant into the freezing chamber 12 and a control unit 32 for adjusting the flow rate of the refrigerant. That is, a liquid refrigerant supply path 34 having a connection port detachably connected to a refrigerant container 33 provided outside the apparatus at one end and the other end connected to the inlet 16b of the refrigerant flow path 16a of the cooling plate 16 is configured as one of the above flow paths 31. From the middle of the liquid refrigerant supply path 34, a gaseous refrigerant supply path 35 whose tip is connected to the refrigerant gas supply unit 21 branches off and is formed. This gaseous refrigerant supply path 35 is another one of the above flow paths 31. Flow rate adjustment valves 34a and 35a are provided respectively from the branch point of the liquid refrigerant supply path 34 and the gaseous refrigerant supply path 35. The flow rate adjustment valve 34a of the liquid refrigerant supply path 34 is referred to as the "main adjustment valve 34a", and the flow rate adjustment valve 35a of the gaseous refrigerant supply path 35 is referred to as the "sub - adjustment valve 35a". Although not shown in the figure, safety valves and emergency shut - off valves are also provided in the flow path 31.

[0021] The main adjustment valve 34a and the sub - adjustment valve 35a are connected to the control unit 32 together with the heater 18a of the heater plate 18 and the motor 24 that drives the fan 22. The control unit 32 is connected to a storage unit storing a plurality of freezing programs together with an input device for operations and the like (not shown in the figure) and an output device for displays and the like. Then, in the freezing process, the selected freezing program is read out, and control operations according to the freezing program are executed for the main adjustment valve 34a, the sub - adjustment valve 35a, the heater 18a, and the motor 24. The temperature sensors 17 and 23 described above are also connected to the control unit 32, and in the control operation by the control unit 32, the temperature information input from the temperature sensors 17 and 23 is referred to.

[0022] The freezing apparatus 11 having such a configuration freezes the object to be frozen as follows.

[0023] When the cell freezing container for accommodating the frozen object is the freezing tube 51, the tube black 52 as shown in FIG. 2 is used. The tube black 52 is composed of a solid block made of a metal with good thermal conductivity, similar to the cooling plate 16. Its shape is a rectangular parallelepiped, and a plurality of holding holes 53 for inserting and holding the freezing tube 51 are evenly arranged on the upper surface. The tube black 52 holding the freezing tube 51 containing the frozen object together with the cryopreservation medium is placed on the cooling plate 16 in the freezing chamber 12.

[0024] After a desired freezing program is selected and the cooling operation is started, the control unit 32 opens the main regulating valve 34a according to the freezing program and supplies liquid refrigerant to the inlet 16b of the refrigerant flow path 16a of the cooling plate 16. The supply amount of the refrigerant is a small amount that vaporizes before passing through the refrigerant flow path 16a, and the refrigerant gas (gaseous refrigerant) whose volume has increased due to vaporization is discharged from the outlet 16c of the refrigerant flow path 16a and diffuses into the freezing chamber 12.

[0025] By filling the freezing chamber 12 with gaseous refrigerant in this way, in the freezing method by the freezing device 11, a purge process of pushing out the air existing in the freezing chamber 12 from the exhaust port 15 is executed. That is, the purge process is a process of purging the air in the freezing chamber 12 with gaseous refrigerant prior to or at the initial stage of the freezing process.

[0026] As the supply of the refrigerant is advanced according to the freezing program and the freezing process proceeds, the temperature of the cooling plate 16 drops, and the temperature of the atmosphere in the freezing chamber 12 also drops. Then, the cooling plate 16 indirectly cools the frozen object through the tube black 52. At the same time, the gaseous refrigerant released from the cooling plate 16 fills the freezing chamber 12 and cools the entire inside of the freezing chamber 12. In this cooling, since the air in the freezing chamber 12 has already been purged, there is no moisture in the freezing chamber 12, and the occurrence of frosting and condensation is prevented.

[0027] During the freezing process, the temperature inside the freezing chamber 12 (ambient temperature) is higher than the temperature of the cooling plate 16 (plate temperature), and cooling proceeds at a uniform rate toward the target temperature while maintaining a temperature difference within a roughly constant range, such as around 20°C.

[0028] During this cooling process, the control unit 32 opens and closes the main control valve 34a based on the detection results (plate temperature information, ambient temperature information) from the temperature sensor 17 on the cooling plate 16 and the temperature sensor 23 in the freezing chamber 12. By opening and closing the main control valve 34a and, if necessary, heating with the heater 18a, highly accurate cooling is achieved, realizing the optimal cooling rate and cooling profile. PID control is recommended for the control unit 32.

[0029] After the freezing process is complete and the frozen object has been removed, the input device is operated to power the control unit 32 to the heater 18a, which allows the cooled cooling plate 16 to be quickly restored to room temperature.

[0030] As described above, liquid refrigerant is supplied to the cooling plate 16, which is in indirectly in contact with the object to be frozen, to cool it. At the same time, gaseous refrigerant is released from the cooling plate 16 to cool the inside of the freezing chamber 12 and freeze it. This allows for uniform cooling without unevenness through two different cooling methods. Moreover, the refrigerant supplied to the cooling plate 16 is vaporized and used to cool the inside of the freezing chamber 12 in a manner that maintains an approximately constant temperature difference between the ambient temperature and the plate temperature. This cools the entire freezing chamber 12 while minimizing refrigerant consumption.

[0031] Furthermore, since the air in the freezing chamber 12 is purged with a gaseous refrigerant prior to or during the initial stages of the freezing process, frost and condensation are prevented, allowing for uniform cooling of the object to be frozen and achieving more appropriate freezing.

[0032] Refrigerants such as liquid nitrogen have high cooling capacity and a wide temperature control range. Furthermore, these effects are not hindered even if the cooling plate 16 is enlarged, so a freezing device 11 can be obtained that takes advantage of the benefits of the refrigerant and can properly freeze a large amount of material to be frozen at once.

[0033] As mentioned above, the freezing device 11 is equipped with a refrigerant gas supply unit 21 and a fan 22, so these can be used for purging and freezing. That is, purging is not performed with refrigerant passed through the cooling plate 16, but rather by introducing refrigerant gas from the gaseous refrigerant supply passage 35 into the freezing chamber 12 at the start of the cooling operation and operating the fan 22 to forcibly perform purging. It is also possible to operate the fan 22 during the freezing process to perform forced convection cooling. Of course, when performing forced convection cooling, refrigerant gas may also be supplied into the freezing chamber 12 through the gaseous refrigerant supply passage 35.

[0034] The above configuration is one embodiment for carrying out this invention, and this invention is not limited to the above configuration; other configurations can also be adopted.

[0035] For example, the freezing device 11 may not have an opening / closing door 14 on its front, but rather a structure in which the top surface is open.

[0036] The refrigerant may be something other than liquid nitrogen.

[0037] If the cell freezing container holding the frozen material is in the shape of a bag, a protector or a holder for holding the protector is used instead of the Tube Rack 52. [Explanation of symbols]

[0038] 11...Freezing device 12...Freezing chamber 15... Exhaust vent 16…Cooling plate 16a... Refrigerant flow path 16b…Entrance 16c…Exit 17…Temperature sensor 18… Heater plate 21... Refrigerant gas supply unit 22...fan 23...Temperature sensor 32…Control Unit 34…Liquid refrigerant supply line 34a... Main control valve (flow control valve) 35…Gaseous refrigerant supply path 35a... Sub-control valve (flow control valve)

Claims

1. A freezing apparatus that uses liquefied gas as a refrigerant and has a freezing chamber with an exhaust port, A metal cooling plate equipped with a refrigerant flow path is provided in the freezing chamber. Liquid refrigerant is supplied to the inlet of the refrigerant flow path, and gaseous refrigerant is released into the freezing chamber from the outlet of the refrigerant flow path. Freezing equipment.

2. A heater plate for heating the cooling plate is provided below the cooling plate. The freezing apparatus according to claim 1.

3. A refrigerant gas supply unit is provided to supply gaseous refrigerant to the freezing chamber, The aforementioned freezing chamber is equipped with a fan. A freezing apparatus according to claim 1 or claim 2.

4. A flow control valve is provided in the liquid refrigerant supply passage that supplies refrigerant to the cooling plate. A control unit is provided that compares the plate temperature information input from a temperature sensor on the cooling plate with the ambient temperature information input from a temperature sensor on the freezing chamber, and opens and closes the flow control valve in order to maintain the temperature difference between the two within a certain range while cooling according to a predetermined freezing program. A freezing apparatus according to claim 1 or claim 2.

5. A freezing method using a freezing apparatus that uses liquefied gas as a refrigerant, Prior to or during the initial stages of the freezing process, the air in the freezing chamber is purged with a gaseous refrigerant. Freezing method.

6. A metal cooling plate with a built-in refrigerant flow path is installed in the freezing chamber where the freezing process takes place. Liquid refrigerant is supplied to the inlet of the refrigerant flow path, and gaseous refrigerant is released into the freezing chamber from the outlet of the refrigerant flow path. The temperature of the atmosphere inside the freezing chamber is maintained at a temperature a certain range higher than the temperature of the cooling plate, while cooling is performed according to a predetermined freezing program. The freezing method according to claim 5.

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