Precision temperature control device for high performance microwave irradiation with metal tube coil

Abstract

To provide a temperature control device for carrying out a reaction or cultivation with control at a constant temperature under condition below a boiling point of a solvent, when performing a chemical reaction with a microwave heating device.SOLUTION: In a multimode device that irradiates the inside of a chamber with microwaves and heats a load body, when a container is input in the device and a reaction is carried out under condition of below a boiling temperature of a solvent, a metallic tube is coiled around the outside of a container made of a material that transmits microwaves, allowing a suitable refrigerant or thermal medium to flow within the metallic tube to maintain and control the desired temperature. Compared to a reaction container without coils, this design improves the microwave irradiation efficiency to an equal or greater extent and make correspond to containers of various shapes and sizes, from small to large.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a multi-mode microwave heating device that irradiates microwaves to heat a load. A metal tube is directly wound in a coil shape along the outside of a reaction vessel that transmits microwaves, and a refrigerant or a heat medium can flow through this metal tube coil, serving as an external coil temperature controller. The present invention relates to a precise temperature control device for high-efficiency microwave irradiation using a metal tube coil, which is characterized in that.

Background Art

[0002] When performing a chemical reaction with a microwave heating device, if there is no temperature control device, the temperature will rise to the boiling point of the solvent and the reaction will be carried out while refluxing. When controlling the temperature to a constant temperature under conditions below the boiling point of the solvent for reaction or culturing, it is necessary to cool with some temperature control device.

[0003] Many studies have been conducted on organic reactions using microwave irradiation, and papers on its mechanism have been published, showing that the reaction rate and reaction yield are improved compared to reactions using normal heating devices. There are some industrial cases where reactions using microwave irradiation have been partially put into practical use. Also in culturing, it has been reported that when culturing using microwave irradiation, the amount of bacteria in the culture medium increases and the growth rate of bacteria becomes faster compared to normal culturing (Non-Patent Document 1). Culturing using microwave irradiation is also considered for future industrial use. However, since many cases require culturing while irradiating microwaves under constant temperature conditions below 50°C, the number of research examples on culturing using microwave irradiation is less than that of organic reactions. Although there are examples implemented with technologies such as air cooling, it is difficult to scale up the technology, and there are no practical cases yet.

[0004] In the reaction or culture using microwave irradiation, as a technique for cooling the reactor, first, there is a method of air cooling (Non-Patent Document 2). However, since the cooling efficiency of air cooling is low, it is effective at high temperatures of several hundred degrees Celsius, but for reactions at low temperatures, measures such as adjusting the microwave output low, irradiating the microwave intermittently, and reducing the capacity are required. When the capacity of the reactor increases, for example, when water is used as a solvent, it becomes difficult to apply under conditions of less than 100°C. There is also a technique for controlling under conditions of 50°C or less using liquefied carbon dioxide gas in the case of air cooling (Patent Document 1). In this case as well, it is effective at the test tube level capacity, but when dealing with a large reaction vessel or increasing the output of microwave irradiation, the amount of liquefied carbon dioxide gas used as the refrigerant will increase, which is not reasonable. Second, there is also a method of cooling the reactor by a double jacket method (Patent Document 2). However, in these methods, when the refrigerant absorbs microwaves, the refrigerant is heated by the microwaves, so the absorption of microwaves is small, and it is necessary to use non-polar refrigerants such as non-polar kerosene and hexane. Kerosene, hexane, etc. have a small heat capacity and poor cooling efficiency. Also, when using refrigerants such as kerosene and hexane, there are problems in terms of safety such as leakage, and it can be applied in small-scale laboratory-level experiments, but safety measures may be difficult in large-scale equipment. Especially in a culture device using microwave irradiation, a device made of glass or resin that transmits microwaves is required, and there is a possibility of leakage due to deterioration or cracks caused by vibration, so the problem of safety is significant especially when scaling up. Third, there is a method using a cooling coil. However, there has been no idea of putting a metallic coil into a microwave device due to concerns about troubles such as arc generation during microwave irradiation (Non-Patent Document 3), and it has been adopted to flow a refrigerant through a coil made of glass or resin (Patent Document 2). In this case, similar to the previous jacket method, the refrigerant to be used needs to be a non-polar refrigerant that does not absorb microwaves such as hexane and kerosene. Furthermore, in the coil, the cooling efficiency is lower than that of the jacket, so measures such as further lowering the refrigerant temperature and increasing the refrigerant flow rate are required. Also, in the coil type, similar to the jacket type, there is a risk of leakage and the problem in terms of safety is significant.In the case of a coil, using a resin tube reduces the concern about cracking, etc., but the heat transfer efficiency deteriorates, so it becomes necessary to further lower the temperature of the refrigerant.

[0005] In addition, in a large-sized reactor, there is also a method of connecting a waveguide to the gas phase part of a general external jacket type chemical reactor and irradiating microwaves from there (Patent Document 3). In this case, there is no restriction on the refrigerant liquid and the temperature conditions can be freely set. However, since the waveguide for microwaves is directly connected to the reactor, it is necessary to use a reactor of a corresponding size, and it may be difficult to apply it to a small-scale reactor, especially at the laboratory experiment level.

[0006] There is also a technology that adopts an external circulation cooling method. A part of the liquid in the reactor in the storage can be taken out of the storage by a tube, cooled by a temperature control device provided outside, and then returned to the device in the storage. However, especially in a culture device, in order to prevent the contamination of miscellaneous bacteria, it is necessary to sterilize the device with heating steam, etc. every time, and there is a problem that the sterilization operation becomes complicated. Simplifying this sterilization operation is also a major issue when scaling up.

[0007] In the case of a reaction solvent with a high boiling point, when maintaining a high temperature, the heat dissipation becomes large. Therefore, in order to minimize this heat dissipation, it is necessary to take measures such as strengthening insulation and increasing its thickness. However, there is a concern that when the thickness of the insulation is increased, the irradiation efficiency of microwaves will inevitably decrease. For this reason, a method of introducing a heat medium at an appropriate temperature that allows microwaves to pass through, such as a jacket or a coil, to the outside of the reaction vessel to block heat, can be considered.

[0008] However, also in this case, a heat medium that does not absorb microwaves is used as in the case of cooling, but it is necessary to use glass or the like for the jacket or coil that also does not absorb microwaves. There is a concern about cracking due to impacts such as deterioration and vibration, and the risk of leakage of the high-temperature heat medium is even higher than when using a refrigerant.

Prior Art Documents

Patent Documents

[0009] Patent Document 1 Japanese Patent Application No. 2010-034070, "Simple Cooling Type Microwave Chemical Reaction Apparatus", Conan Electronics Co., Ltd. Patent Document 2 Japanese Patent Application No. 2006-513675, "Cooling Type Microwave Chemical Reaction Apparatus", National Institute of Advanced Industrial Science and Technology, Shikoku Measurement Industry Co., Ltd. Patent Document 3 Japanese Patent Application No. 2006-512547, "Chemical Reaction Apparatus Using Microwaves", Sanko Chemical Industry Co., Ltd., Shikoku Measurement Industry Co., Ltd. JP4145335B2, "Chemical Reaction Apparatus Using Microwaves", Shikoku Measurement Industry Co., Ltd. Non-Patent Document

[0010] Non-Patent Document 1 Sterilization and Cultivation of Microorganisms under Microwave Irradiation, Chapter 4 of "Microwave Chemical Process Technology II", Application of Microwave Chemistry to Biotechnology, p184, CMC Publishing (2013) Non-Patent Document 2 Technical Data of Biotag Co., Ltd., "Heating While Cooling" or "Enhanced Microwave Reaction" Non-Patent Document 3 JEMEA Bulletin Vol.5 No.1 (2020.2), "Microwave Device Specialized for Chemical Reactions", 12th JEMEA Symposium, 2018 Short Course, Shikoku Measurement Industry Co., Ltd. Summary of the Invention

[0011] In a multi-mode microwave irradiation heating device of the microwave oven type that irradiates microwaves into a chamber to heat a load, when a reaction vessel is placed in the device and a chemical reaction or culture is carried out by microwave irradiation under conditions below the boiling point of the solvent, a metal tube is directly wound in a coil shape along the outside of a reaction vessel made of a material that transmits microwaves, such as glass or resin. The metal tube used for introducing / discharging a refrigerant or a heat medium is passed through a cylindrical hole provided in the side wall or the upper part of the microwave device, and is connected to the introduction / discharge metal tube via metal at both ends of the coil wound around the container. A refrigerant or a heat medium can be passed through the coil of the metal tube wound around this reaction vessel, and from each of these two metal tubes, or from each of both end portions of the coil, two or more main body earthings are taken to form an external temperature controller. It is a precise temperature control device for high-efficiency microwave irradiation using a metal tube coil, characterized in that a constant temperature state at a desired temperature can be maintained while irradiating microwaves.

[0012] As an external temperature controller with a wound coil, it can correspond to almost all types of reaction vessels, such as beaker type, Erlenmeyer flask type, round bottom flask type, and narrow test tube type. Since microwaves are shielded by the metal, there is no restriction on the type of refrigerant flowing inside the metal tube, and a reaction or culture by microwave irradiation can be carried out using a refrigerant or a heat medium suitable for maintaining and controlling a constant temperature at a temperature below the desired boiling point.

[0013] In order to improve the cooling efficiency and increase the heat transfer, a resinous heat transfer body for closely adhering the coil to the reactor can also be used. Also, for heat insulation, the outside of the coil can be covered with a resin or glass fiber that transmits microwaves to provide heat insulation.

Problems to be Solved by the Invention

[0014] In a precise temperature control device for high-efficiency microwave irradiation using a metal tube coil, it is desired to have an external temperature controller that can freely set temperature conditions below the boiling point of the reaction solvent, maintain and control a constant temperature, freely select the type of refrigerant, and be applicable to reactors ranging in size from small to large. In particular, in a culture device using microwave irradiation, many require temperature conditions of about 0°C to 50°C, and culture devices of various sizes are needed from small-scale culture to medium-scale culture and large-scale culture. It is desired to have a cooling-type culture device that can be applied to these and has a simpler structure. Also, when scaling up from a small-scale reactor to a large one, if it is an external temperature control method, the scale-up technology of the reactor that has been conventionally studied can be applied, and the design during scale-up may become simpler. Moreover, if it is an external temperature control method, the inside of the culture device can be simplified and the sterilization operation can be made easier.

[0015] Furthermore, when the boiling point of the reaction solvent is high and maintaining the temperature at a high temperature, it is desired to have an external temperature controller that can block heat with an appropriate heat medium, reduce the thickness of the heat insulation for preventing heat dissipation of the reactor, and enable more efficient irradiation of microwaves into the reaction vessel.

[0016] Introducing metal into a multi-mode microwave heating device increases the risk of arc generation, and even when grounding is used to deal with it, it is considered that the amount of microwaves returning from the microwave irradiation port to the magnetron may increase, which poses a safety problem and is generally not recommended. That is, when a metal tube coil is directly wound around the reactor, it was considered that the microwave irradiation efficiency may extremely decrease even when grounded, so there is a possibility that the microwaves that did not penetrate the load body may cause arc discharge in various places in the chamber, and also the amount of microwaves returning from the irradiation port to the magnetron may increase, which may cause the magnetron to generate heat more than the cooling capacity of the fan and become overheated, posing a safety problem, and it has been considered that it has not been applicable to putting a metal tube coil in the chamber.

Means for Solving the Problem

[0017] In the present invention, in a multi-mode microwave heating apparatus, a high-efficiency microwave irradiation precision temperature control device using a metal tube coil, in which a metal tube is directly wound in a coil shape along the outside of a reaction vessel made of a material that transmits microwaves, such as glass or resin. The metal tube used for introducing / discharging a refrigerant or a heat medium is passed through a cylindrical hole provided in a lateral wall or an upper part of the multi-mode microwave heating apparatus, and is connected to this metal tube via metal to both ends of the coil wound around the container, so that a refrigerant or a heat medium can flow through the metal tube coil wound around this reaction vessel. Each of these two metal tubes, or a structure in which body earthing is taken from two or more places at each of both end portions of the coil. When microwaves are irradiated in the storage of the microwave heating apparatus, it has been discovered that the irradiation efficiency can be improved to be equal to or higher than that in the case of a reaction vessel (blank) without a coil wound, and microwaves can penetrate more efficiently into the load body in the reactor.

[0018] Furthermore, it has been found that the effect of improving this irradiation efficiency can be applied to almost all types of shapes, including beaker type, Erlenmeyer flask type, round-bottom flask type, and narrow-diameter test tube type. In the precision temperature control device for high-efficiency microwave irradiation using a metal tube coil that allows a refrigerant or heat medium to flow through this tube coil, since the inside of this metal tube is not affected by microwaves, various refrigerants or heat media suitable for achieving the temperature required for the intended reaction or culture can be flowed through. As a result, it has been successful in creating a constant temperature state at a desired temperature below the boiling point of the reaction solvent in reaction vessels of almost all the above-mentioned types of shapes. Also, for example, when attempting to maintain a temperature at a high temperature of 100 °C or higher, the temperature difference from the outside air becomes large, and heat dissipation easily causes a temperature drop, so it was necessary to increase the thickness of the heat insulation layer to cope with this. However, by using this temperature control device and flowing a heat medium at an appropriate temperature through the metal tube coil, since this temperature control device blocks heat from the outside air, heat dissipation inside the reaction vessel can be reduced. Furthermore, with the increase in the microwave irradiation efficiency, it becomes easier to maintain the temperature. For the connection between the metal tube and the metal at the coil end, not only joints using metal ferrules but also resin joints and tubes that can withstand the flowing refrigerant or heat medium are used to connect so that the refrigerant liquid or heat medium liquid does not leak. After that, each of the introduction / discharge (in / out) metal tube and the coil end can be connected with a metal wire or a metal plate, etc.

Advantages of the Invention

[0019] When this metal tube is wound around the outside of the reaction vessel in a coil shape and grounded at only one point, it was found that the microwave irradiation efficiency may deteriorate with respect to blank. Also, for example, when grounding is taken at only one point at one end of the metal tube, the potential difference from the other metal tube part becomes maximum, so the possibility of arc generation increases. Therefore, in order to eliminate this potential difference, it was considered to take body ground from each of the both ends of the coil. By this way of grounding, compared with the blank state where the metal tube coil is not wound, the microwave irradiation efficiency became equal to or higher than before. By eliminating the potential difference at both ends, the risk of unexpected arc generation is also reduced, and the improvement of the irradiation efficiency means that the microwave is absorbed by the load body, so it is considered that the risk of unexpected arc generation is avoided doubly. By using the metal tube coil shown in this technology, the concerns about the risks in terms of safety that have been considered so far will be eliminated. Also, by using a metal coil, the risk of cracks and fractures due to deterioration and impact is reduced, and the risk of leakage of the refrigerant or heat medium is eliminated.

[0020] Since the inside of this metal tube coil is not affected by microwaves, various refrigerants or heat media can flow regardless of microwave absorption. So far, organic compounds such as water, alcohol-based ethylene glycol, and diethylene glycol, which have a large microwave absorption and are usually not usable in microwave heating due to their polarity and large heat capacity, can be used as refrigerants or heat media, and there is no restriction on the use of refrigerants or heat media. That is, an appropriate refrigerant or heat medium along the temperature conditions can be selected and used without restriction in terms of type while considering its melting point and boiling point, so that tests can be carried out while maintaining a constant temperature state at a desired temperature below the boiling point of the solvent used for the reaction or culture under microwave irradiation.

[0021] By changing the temperature, circulation rate, etc. of the refrigerant or heat medium, it is possible to carry out a reaction under conditions below the boiling point of the solvent used. For example, in the case of a reaction using water as the solvent, the reaction can be carried out at a desired temperature of 0 °C to less than 100 °C. Also, during culturing or enzymatic reactions, tests can be conducted under microwave irradiation at a temperature controlled at an optimal temperature of 0 to 50 °C. Furthermore, even when reacting with an organic substance having a high boiling point of 100 °C or higher as the solvent, since there are no problems with risks such as leakage of the refrigerant or heat medium, it is also possible to test a microwave reaction controlled at a desired constant temperature of 100 °C or higher. In particular, usually, tap water, a refrigerant circulation device, or a heat medium circulation device commonly used for temperature adjustment can be used, and there is an advantage in that the temperature control system can be simplified. Also, it is a temperature control system independent of the reactor, and by changing the type of coil, the type and capacity of reactors such as Erlenmeyer flasks and round-bottom flasks can be changed, and there is also an advantage in that internal cleaning and sterilization of the reactor itself are easy.

[0022] Also, regarding a reactor with a coil of a metal tube, since the irradiation efficiency is improved equally or more compared to the reactor when the microwave does not wind around the coil, an improvement in energy saving can also be expected. In small-scale reactions or small-scale culturing, the merit of being able to suppress the microwave output is small, but in industrial medium-scale and large-scale facilities, the improvement in energy efficiency directly means an effect of saving energy and reducing energy costs. Also, in particular, even when a solvent with an extremely low dielectric constant at high temperatures is used, the effect of improving the microwave irradiation efficiency is more preferable because the microwave output does not need to be increased extremely.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0024] In a multi-mode microwave heating device that irradiates microwaves into a storage chamber to heat a load body, when various reaction vessels that transmit microwaves, such as beaker type, Erlenmeyer flask type, round-bottom flask type, and even thinner test tube type, are placed inside the device and reactions are carried out under conditions below the boiling point of the solvent, or culturing or enzymatic reactions are carried out while irradiating with microwaves, a metal tube is wound in a coil shape along the outside of these reaction vessels, and a refrigerant or a heat medium is allowed to flow through this metal tube to control the temperature, thereby providing a precision temperature control device for high-efficiency microwave irradiation using a metal tube coil for carrying out a constant temperature reaction at a desired temperature.

[0025] Here, a precision temperature control device for high-efficiency microwave irradiation using a metal tube coil is defined as follows based on the shape of the coil. (a) "Beaker type" is cylindrical and the diameter of each stage of the coil is the same. Wide-mouth bottles and narrow-mouth bottles also fall under this category. (b) "Erlenmeyer flask type" is such that the diameter of the coil gradually increases from the top to the bottom of the container. Conical beakers also fall under this category. (c) The "round-bottom flask type" is a type where the diameter is the largest in the middle of the container, and a coil is wound around the part that becomes smaller in a bowl shape from this maximum diameter part. Eggplant flasks, three-neck flasks, etc. correspond to this. Also, flat-bottom flasks are added to this type. (d) The "test tube type" is cylindrical, and like the beaker type, each stage of the coil has the same diameter, and the diameter of the container is 50 mm or less. In addition to test tubes, sample bottles, etc. correspond to this. Representative examples of these apparatuses with coils wound are shown in Figs. 1(a) to (d).

[0026] In temperature control using a metal tube coil, the temperature inside the reactor is controlled by the heat transfer between the reaction vessel and the coil tube, depending on the temperature and flow rate of the refrigerant or heat medium flowing inside the coil tube. Therefore, for the metal tube wound around the reaction vessel, it is necessary to select an optimal tube diameter and number of turns according to the size of the vessel. If the number of turns is small, the contact area and heat transfer area between the reaction vessel and the coil will be small, resulting in limitations in temperature control. In order to improve the heat transfer efficiency, it is also possible to take measures such as using a resinous heat transfer body that transmits microwaves to closely adhere the coil and the reactor, or covering and heat insulating the outer surface of the wound coil with a resin or glass fiber that transmits microwaves. Also, especially when the reaction vessel is a beaker, Erlenmeyer flask, or test tube with a volume of 100 ml or less, since the diameter of the vessel becomes smaller, for example, with a metal tube having a tube diameter of 6 mm or more, not only does the number of turns decrease, but it also becomes difficult to wind it in a coil shape along the vessel. Therefore, for these vessels, it is better to use, for example, a metal tube with a tube diameter of 4 mm or less. Also, since the height of the vessel also affects the number of turns, when the height of the vessel is low, it is similarly preferable to use a metal tube with a tube diameter of 4 mm or less.

[0027] In addition, as the metal tube used for the coil, commercially available metal tubes such as copper tubes, stainless steel tubes, and aluminum tubes can be used. Also, the tube diameter of the metal tube can be 2 mm or more. When the tube diameter is reduced, for example, in the case of a copper tube with a tube diameter of 2 mm, the inner diameter is generally about 1 mm, and the flow rate of the medium flowing through the tube is restricted. However, it has been found that when the microwave output is low and the heat removal amount is small, a coil with a tube diameter of 2 mm is also effective. However, when the capacity of the reaction vessel increases or the microwave output increases, the heat removal capacity is insufficient if the flow rate of the medium flowing through the coil is low. In this case, in order to ensure the flow rate flowing through the metal tube, it is desirable to use a metal tube with a tube diameter of preferably 3 mm or more, more preferably 4 mm or more.

[0028] Regarding the number of turns of the coil when winding the coil, considering the size of the container and the heat-up efficiency, it is better to have as many turns as possible. Therefore, when the minimum number of turns was confirmed, it was found that when the coil has 2 turns or more, the irradiation efficiency is equal to or higher than that of the blank without winding the coil. Also, the way of winding the coil is usually expressed by the coil pitch. However, considering that the irradiated microwave passes between the tubes of this coil and enters the reaction vessel side, it is more preferable to use the interval between the coils rather than the coil pitch as an index, and it is necessary to define the minimum coil interval. It has been found that when this coil interval is 4 mm or more, the irradiation efficiency of the microwave is improved compared to the blank without winding the coil. Regarding the number of turns of the coil and the way of winding the coil, when the type and capacity of the reaction vessel used in the test and the tube diameter of the coil are determined, the length within the range where the coil can be wound is determined from the height of the reaction vessel. From this length, the upper limit of the number of turns of the coil with a coil interval of 4 mm or more is determined. The number of turns of the coil can be selected as the optimal number of turns from 2 turns to this upper limit of the number of turns in consideration of the microwave output and the heat removal efficiency.

[0029] It is necessary to connect the coil end of the reaction vessel with the coil wound and the metal pipe for introducing / discharging (inlet / outlet) the refrigerant or heat medium in order to take the main body ground. However, since the experiment basically requires performing repeated tests etc., it is not reasonable to disassemble the whole each time. With a microwave irradiation device, it is also possible to devise a method to efficiently extract the reaction solution or the culture solution by providing a bottom-drilling hole and then be able to wash the reaction vessel in its original state, but modification for this purpose is required. Therefore, it is desirable to make it possible to easily connect and disconnect the reaction vessel with the coil wound and the inlet / outlet metal pipe in the existing inventory of the microwave irradiation device. To make a connection via metal at each of the inlet / outlet metal pipe and the coil end part, not only a joint using a metal ferrule but also a resin joint resistant to the refrigerant or heat medium, and after connecting with a resin or rubber tube etc. so that the refrigerant liquid or heat medium liquid does not leak, the inlet / outlet metal pipe and the coil end part may be connected with a metal wire, a metal plate etc.

[0030] As a way of taking the main body ground of the temperature control device, when grounding is taken from two or more places at each of the inlet / outlet metal pipe parts, it has been found that the potential difference between the two metal pipes disappears and furthermore the irradiation efficiency is improved compared to blank. When the main body ground is taken at only one place, for example, when the main body ground is taken only with one of the inlet / outlet metal pipes, the potential difference becomes maximum between the other metal pipe part and the risk of arc generation increases. Also, it has been found that by taking the ground at only one place compared to the case where the ground is taken at two or more places, the irradiation efficiency decreases in all cases and may deteriorate compared to blank without the coil wound. This is not preferable because it is considered that the risk of arc generation further increases.

[0031] In a temperature control device with a coil wound, for the method of passing the metal pipe for introducing / discharging the refrigerant or heat medium through the tube hole of a multi-mode microwave irradiation device, in the case of a microwave irradiation device having tube holes in the transverse wall and the upper part, the following 3 patterns can be made. Pattern A: Pass both the inlet / outlet metal pipes through the tube hole in the transverse wall Pattern B: Pass both the inlet / outlet metal pipes through the tube hole in the upper part Pattern C: Pass each of the metal pipes for introduction / discharge through the lateral wall and the upper cylindrical hole Among these, in Pattern B where both metal pipes are passed through the upper cylindrical hole, it sometimes deteriorated compared to the blank without the coil wound. However, in Pattern D where an earth is added from the coil end to the lateral wall to have three earth points, it was confirmed that the irradiation efficiency is improved compared to the blank. Pattern D: Add the main body earth from the coil end in Pattern B (three earth points) By devising the way of taking the main body earth in these four patterns, the irradiation efficiency could be improved in all patterns. That is, it was found that by taking the earth at two or more points, it is possible to select the pattern of the arrangement of the metal pipes for input / output to be adopted according to the type and volume of the reaction vessel.

[0032] A temperature control device using metal tube coils of beaker type, Erlenmeyer flask type, round-bottom flask type, and narrow test tube type with coils wound, was modified to allow water to flow as a refrigerant. It was set inside a multi-mode microwave irradiation device. A predetermined amount of water was placed in the reaction vessel, and continuous microwave irradiation was performed. When testing the effects of microwave output, refrigerant temperature, insulation, etc., it was confirmed that a constant temperature state could be maintained and controlled in all these types. In this experiment, water with a temperature of 8°C was used as the refrigerant instead of tap water at room temperature, and tests were conducted at microwave outputs of 30 W to 150 W. It was possible to control the constant temperature state at temperatures from 32°C to 93°C. When controlling a constant temperature state below room temperature, condensation may occur on the coils and metal tubes depending on the indoor humidity. Microwaves are also absorbed by the condensed water, making it difficult to maintain a constant temperature state inside the reaction vessel. Therefore, it was found that dew prevention by insulation is necessary as required. It is also possible to adopt an even lower temperature as the refrigerant, and temperature control below 30°C is also possible. Additionally, by controlling the temperature of the refrigerant with a refrigerant circulation device, it is possible to maintain a constant temperature state with even higher accuracy. In this experiment, each reaction vessel was tested in an open system. However, when conducting long-term tests under high-temperature conditions, the liquid volume inside the reactor decreases due to evaporation, so it is necessary to equip with a reflux pipe as required. In the case of culture tests, it is necessary to conduct tests in a closed system to prevent contamination by foreign bacteria, and in some cases, it may not be possible to insert a thermocouple or the like into the culture vessel. In such cases, it is also possible to monitor with a thermometer closely attached to, for example, the bottom surface of the reaction vessel, where the influence of the coil does not occur. When actually conducting tests at a constant temperature, it is desirable to perform preliminary tests in advance to determine the test conditions such as the type and capacity of the reaction vessel, and to select the desired temperature to be set. By matching the type and volume of the solvent, microwave output, selection of the optimal refrigerant, and optimization of refrigerant temperature and flow rate. In actual reactions and cultures, there may be a slight temperature deviation due to reaction heat, etc. This deviation can be finely adjusted with the microwave output, but when conducting a comparative test with the microwave output conditions matched, it is desirable to finely adjust with the temperature and flow rate of the refrigerant or heat medium.

[0033] Furthermore, in a precise temperature control device for high-efficiency microwave irradiation using a metal tube coil, it may take a considerable amount of time for the refrigerant to flow from the beginning until it reaches the desired temperature. For example, in a 300 ml Erlenmeyer flask with a microwave output of 50 W, it took more than 90 minutes to reach a constant temperature state around 50°C. Depending on the volume, set temperature, and microwave output, even more time may be required. As a countermeasure, in addition to raising the temperature by microwave irradiation, by using a heat medium close to the set temperature inside the coil tube, the set temperature can be reached faster than by normal microwave irradiation temperature rise. Then, by switching to the refrigerant temperature for maintaining the set temperature, it was also confirmed that the time until the constant temperature state can be shortened to about 40 minutes. Furthermore, to raise the temperature to the desired temperature range, it can be achieved by increasing the heating rate. For example, (1) increasing the temperature and flow rate of the heat medium and switching to the refrigerant near the target temperature, (2) increasing the microwave output and switching to the refrigerant near the target temperature, or corresponding by both (1) and (2) are conceivable methods. Furthermore, it is also possible to start from a temperature close to the target temperature. That is, after determining the type and volume of the solvent to be used in advance, by performing the optimization of microwave output, selection of the optimal heat medium / refrigerant, and their flow rates, etc. in advance, a constant temperature state can be achieved early.

Example

[0034] Next, the examples of this patent will be described. In the experiment, a μReactor manufactured by Shikoku Keisoku Kogyo Co., Ltd. was used as the microwave heating device, but it is not limited to this example only. Also, regarding the size of the reaction device, the state of the coil, etc., it is not limited to this example.

[0035] Examples of the production of a device in which a copper tube with a diameter of 2 - 6 mm was wound in a coil shape along the outside of each of a beaker type, Erlenmeyer flask type, round bottom flask type (eggplant flask or three-necked flask), and a thin test tube type, which are glass containers, are shown in FIGS. 1(a), (b), (c), and (d) for each type of container.

[0036] There are several patterns for inserting the device wound with these coils into the chamber of a multi-mode microwave irradiation device and passing the inlet and outlet pipes through which the refrigerant flows. First, it is a method of passing through the cylindrical hole in the side wall of the multi-mode microwave device. In the μReactor, it is located in the vertical direction not facing the irradiation port. This is called Pattern A (see Fig. 2(1)). Second, it is a method of passing through one of the three cylindrical holes left at the top. Among the three cylindrical holes, the middle cylindrical hole is used for passing a stirring rod or a thermocouple, so one of the side cylindrical holes is used. This is called Pattern B (see Fig. 2(2)). Third, it is a method of using both the side wall and the top cylindrical hole. This is called Pattern C (see Fig. 2(3)). Also, in the state of Pattern B, the one with an additional body ground from near the coil end is called Pattern D (see Fig. 2(4)).

[0037] The devices of each pattern were assembled and the body ground was taken at the root of the cylindrical hole. Furthermore, the cylindrical hole was blocked from the outside using aluminum foil. This is meant to control the external leakage of microwaves through the metal pipe. Actually, when measuring the microwave leakage amount, it was confirmed that the leakage amount is at a non-problematic level even without blocking with aluminum foil, but it was blocked with aluminum foil just in case. Also, a thermocouple for temperature monitoring was used in all experiments. For this as well, the body ground was taken at the upper cylindrical hole part where the thermocouple is inserted, and furthermore, the surrounding was blocked with aluminum foil and tested. It was also confirmed that the leakage amount of microwaves is at a non-problematic level.

[0038] First, regarding putting the device with the metal tube coil into the chamber of the microwave irradiation device, in order to confirm whether the risk of arc generation or the like can be avoided, an external temperature control device with a metal tube coil wound around each of the glass containers of (a) beaker type, (b) Erlenmeyer flask type, (c) round-bottom flask type, and (d) test tube type was used. Without flowing a refrigerant or a heat medium, water was put into the reaction vessel and a microwave irradiation test was conducted to measure the temperature rise amount ΔT. Combining with the temperature rise amount ΔT measured with a blank without a wound metal tube coil, the irradiation efficiency of the microwave by this temperature control device was calculated. Then, taking the irradiation efficiency of the blank without a wound coil as 1.0 (reference) for each type of reaction vessel, the irradiation efficiency ratio of this temperature control device with a wound coil was obtained, and how the irradiation efficiency changes was sorted out.

[0039] Next, the refrigerant or the heat medium was allowed to flow through this temperature control device, and a constant temperature test by continuous microwave irradiation was conducted for representative examples of all types of reaction vessels to test whether a constant temperature state could be maintained. The following are these examples.

Example

[0040] As a beaker-type device with a wound coil shown in Fig. 1(a), first, a device with a coil wound around a 6 mm diameter copper tube was fabricated in a 500 ml beaker. 400 g of water was put into the beaker, and this was placed at the center of the chamber of the μReactor. The inlet and outlet metal tubes were passed through the cylindrical holes in the patterns A to C shown in Fig. 2 and connected to both ends of the coil through the metal. The body ground was taken at the root of the cylindrical hole through the metal tube, and the outside of the cylindrical hole was shielded with aluminum foil. While stirring with a magnetic stirrer, the microwave of 200 W was irradiated for 20 minutes, and the temperature change was monitored with a thermocouple. 400 g of water was similarly put into a 500 ml beaker without a wound coil, and while stirring with a magnetic stirrer, the microwave of 200 W was irradiated for 20 minutes, and the temperature change was monitored with a thermocouple to compare the temperature rise amount ΔT. The coil specifications and experimental conditions are shown in the upper part of Table 1.

[0041] The change in the temperature rise ΔT of these tests is shown in Fig. 3. Here, the temperature rise ΔT indicates how much the temperature has risen based on the starting temperature T0 (ΔT = T n - T0; T n is the temperature after n minutes). In Fig. 3, in all cases of pattern A passing through the cylindrical holes in the transverse wall, pattern B passing through the upper cylindrical holes, and pattern C passing through the cylindrical holes in the transverse wall and the upper part, the temperature rise ΔT is larger than that of the blank without the coil wound.

[0042] Based on these temperature rises ΔT, the irradiation efficiency was calculated, and the test results of calculating the irradiation efficiency ratio with the irradiation efficiency of the blank set to 1.0 are shown in the lower part of Table 1. In this table, due to the influence of the temperature dependence of the dielectric constant of the load and heat dissipation, etc., the calculations were performed in two ways: based on time and based on temperature. For the time basis, the heating rate was obtained by linear approximation from the temperature rise ΔT with an irradiation time of 20 minutes, and the irradiation efficiency of the microwave was calculated using the irradiation energy calculated from the heating energy and the irradiation output of the microwave. Also, the irradiation efficiency ratio was obtained from the ratio with the irradiation efficiency of the blank. When this ratio is 1.0 or more, it indicates that the irradiation efficiency is improved compared to the blank, and the larger the value, the more the microwave penetrates into the load (here water) in the reaction vessel in the externally temperature-controlled device with the coil wound. When the irradiation efficiency ratio is less than 1.0, it indicates that the irradiation efficiency deteriorates compared to the blank. Also, for the temperature basis, based on the temperature rise ΔT of the blank reached after 20 minutes of microwave irradiation, in the experiment of the device with the coil wound, the heating rate was obtained at the time when the temperature rise equivalent to the temperature rise ΔT of the blank was reached, and similarly, the irradiation efficiency and the irradiation efficiency ratio were calculated. Considering that the temperature reached by the blank is close in the temperature basis, the dielectric constant and the heat dissipation amount of the load are close to those of the blank, so it is preferable for comparing the irradiation efficiency. The concepts of these time basis and temperature basis are illustrated using pattern A in Fig. 3 as an example. In addition, in this experiment, the increase in the heat capacity of the reaction vessel due to directly winding the coil around the reaction vessel and the increase in the heat dissipation amount due to heat transfer from the coil part, etc. are not considered, and it can be considered that the actual irradiation efficiency is improved compared to the blank even when the irradiation efficiency ratio is 1.0. Table 1. Microwave Irradiation Test of the Device for 500 ml Beakers TIFF2025105312000002.tif6679

[0043] In the test of the 500 ml beaker, when comparing with the irradiation efficiency ratio, both in terms of time standard and temperature standard "Pattern A > Pattern C > Pattern B > blank(=1.0)" It was confirmed that in all cases of Pattern A, B, and C, for the 500 ml container without a wound coil (blank), the irradiation efficiency was improved with this device with a wound coil.

Example

[0044] As other beaker types, with 1000 ml, 300 ml, 200 ml, and 100 ml beakers, under the conditions of Pattern A (both the input and output metal tubes pass through the cylindrical holes in the side wall of the microwave device) and Pattern C (one passes through the upper cylindrical hole and the other passes through the side wall cylindrical hole), with the device specifications and test conditions shown in Table 2, while stirring with a magnetic stirrer, a microwave irradiation test was carried out and the temperature change was monitored. Example 2-1: 1000 ml beaker (coil with a pipe diameter of 6 mm); Pattern C Example 2-2: 300 ml beaker (coil with a pipe diameter of 6 mm); Pattern C Example 2-3: 200 ml beaker (coil with a pipe diameter of 4 mm); Pattern A Example 2-4: 100 ml beaker (coils with pipe diameters of 2, 3, and 4 mm); Pattern A For beakers of each capacity, a microwave irradiation test was carried out on the blank without a wound coil, and the temperature rise amount ΔT was compared. Regarding the 100 ml beaker, devices were fabricated with the same number of turns while changing the pipe diameter of the copper tube wound around the coil to 2, 3, and 4 mm to confirm the influence of the pipe diameter.

[0045] Fig. 4 shows a comparison of the temperature rise amount ΔT when microwave irradiation tests were conducted with the coil having the same number of turns for the pipe diameters of Examples 2-4 being 2, 3, and 4 mm. Also, similar to the case of Example 1, the coil specifications and test conditions of each device are shown in the upper part of Table 2, and in the lower part of Table 2, based on the respective temperature rise amounts ΔT, the irradiation efficiency and irradiation efficiency ratio were calculated with respect to the time reference and temperature reference. The test results of the 500 ml beaker of Example 1 were also included in Table 2.

[0046] In the 500 ml beaker and 300 ml beaker, the irradiation efficiency showed a significant improvement compared to the blank. Looking at the irradiation efficiency ratio, it was 1.79 and 1.68 with respect to the temperature reference and 1.37 and 1.45 with respect to the time reference, respectively, showing a large difference with respect to the temperature reference. This is because at 20 minutes with respect to the time reference, the temperature rise amount ΔT had a difference of about 20°C compared to the blank, resulting in a significant decrease in the dielectric constant and heat dissipation. In the 200 ml and 1000 ml beakers, the temperature difference at 20 minutes was less than 5 degrees, and the difference in heat dissipation was also small. However, since the temperature was monitored and compared every minute, even a difference of less than 5 degrees was significant, and the irradiation efficiency was considered to be equal to or higher than that of the blank (the irradiation efficiency ratio was 1.0 or higher), indicating an improvement in the microwave irradiation efficiency. Also, when coils were wound with the same number of turns for pipe diameters of 2, 3, and 4 mm in the 100 ml beaker, all showed an irradiation efficiency ratio of 1.0 or higher, being 1.10 - 1.17 with respect to the time reference and 1.20 - 1.34 with respect to the temperature reference, and the improvement widths of the irradiation efficiency with respect to both references were also close. From this, it is shown that by appropriately setting the number of turns of the coil and the coil interval, a pipe diameter of 2 - 4 mm has little effect on the irradiation efficiency improvement effect.

[0047] In the beaker type, since the irradiation efficiency is improved to be equal to or higher than that of the blank without winding the coil up to the 100 ml - 1000 ml beakers, it is considered that even if this device with a metal tube coil wound is placed in the multi - mode microwave irradiation device, the risk of unexpected arc generation can be avoided, indicating that this device with a metal tube coil wound can be applied. Also, the fact that the experimental scale can be selected according to the purpose from 100 ml to 1000 ml provides a high degree of freedom and is useful in conducting various studies. TIFF2025105312000003.tif13573

Example

[0048] As a triangular flask-shaped device with a wound coil (see Fig. 1(b)), first, a device with a wound coil was fabricated in a 300 ml triangular flask. 300 g of water was put into the triangular flask, and this was placed at the center of the inside of the μReactor. The inlet and outlet metal tubes were passed through according to the patterns A - C shown in Fig. 2 and connected to both ends of the coil via the metal. As shown in Fig. 2, the body ground was taken at the root of the cylinder hole, and the outside of the cylinder hole was shielded with aluminum foil. While stirring with a magnetic stirrer, microwave irradiation of 200 W was carried out for 20 minutes, and the temperature change was monitored with a thermocouple. 300 g of water was similarly put into a 300 ml triangular flask without a wound coil, and while stirring with a magnetic stirrer, microwave irradiation of 200 W was carried out for 20 minutes, and the temperature change was monitored with a thermocouple to compare the temperature rise amount ΔT. The coil specifications and experimental conditions are shown in the upper part of Table 3. Table 3. Microwave Irradiation Test of 300 ml Triangular Flask Device TIFF2025105312000004.tif5187 Pattern A: Pass two metal tubes through the cylinder holes in the transverse wall Pattern B: Pass two metal tubes through the upper cylinder holes Pattern C: Pass two metal tubes through the transverse wall and the upper cylinder holes Pattern D: Add body ground from one end of the coil in the state of Pattern B (three grounding points)

[0049] The transition of the temperature rise amount ΔT of these tests is shown in Fig. 5. In Fig. 5, in Pattern A where the metal tubes pass through the cylinder holes in the transverse wall and Pattern C where the metal tubes pass through the transverse wall and the upper cylinder holes, the temperature rise amount ΔT was larger than that of the blank. However, in Pattern B where the metal tubes pass through the upper cylinder holes, the temperature rise amount ΔT was smaller than that of the blank. In Pattern D where body ground was taken from one end of the coil in Pattern B where both metal tubes pass through the upper cylinder holes and three body grounding points were set, the temperature rise amount ΔT increased compared to the blank.

[0050] Based on these temperature increases ΔT, the test results of calculating the irradiation efficiency ratio with the irradiation efficiency of the blank set to 1.0 are shown in the lower part of Table 3. Looking at the irradiation efficiency ratio with respect to the blank based on the temperature standard, it was 1.20 for Pattern A where a metal tube passes through the cylindrical hole in the side wall, 0.9 for Pattern B where a metal tube passes through the cylindrical hole in the upper part, which is less than 1.0. However, for Pattern D where an additional main body ground was taken from one location at the end of the coil, it was 1.06, and the irradiation efficiency improved beyond 1.0. Pattern C where metal tubes pass through the cylindrical holes in both the upper part and the side wall showed an irradiation efficiency of 1.01, which was almost equivalent. As described in Example 1 above, increases in the heat capacity of the reaction vessel due to directly winding the coil around the reaction vessel and increases in the heat dissipation amount due to heat transfer from the coil part were not considered. Even when the irradiation efficiency ratio is 1.0, it is considered that the actual irradiation efficiency is improved compared to the blank. Comparing each irradiation efficiency ratio, "Pattern A > Pattern D > Pattern C ≒ blank > Pattern B" was confirmed. From this, it can be said that by taking the ground at two or more locations, the irradiation efficiency of the device with the coil wound is improved compared to the blank of the container without the coil wound.

Example

[0051] As another type of Erlenmeyer flask, in Example 3, with a 300 ml Erlenmeyer flask, under the conditions of Pattern A (both the inlet and outlet metal tubes pass through the cylindrical holes in the side wall of the microwave device) where the improvement in irradiation efficiency is good, with 500 ml, 200 ml, and 100 ml Erlenmeyer flasks, under the device specifications and test conditions shown in Table 4, a microwave irradiation test was conducted while stirring using a magnetic stirrer, and the temperature change was monitored. For each Erlenmeyer flask with different volumes, a microwave irradiation test was conducted on the blank without the coil wound, and the temperature increase ΔT was compared. Example 4 - 1: 500 ml Erlenmeyer flask (coil with a tube diameter of 6 mm); Pattern A Example 4 - 2: 200 ml Erlenmeyer flask (coil with a tube diameter of 4 mm); Pattern A Example 4 - 3: 100 ml Erlenmeyer flask (coil with a tube diameter of 4 mm); Pattern A

[0052] Similar to the case of Example 3, the coil specifications and test conditions of each device were shown in the upper part of Table 4. Based on the respective temperature rise amounts ΔT, the irradiation efficiency and irradiation efficiency ratio were calculated with respect to the time standard and temperature standard in the lower part of Table 4. The test results of the 300 ml Erlenmeyer flask of Example 3 were also included in Table 4. TIFF2025105312000005.tif11376

[0053] It was found that in 500 ml, 300 ml, 200 ml, and 100 ml Erlenmeyer flasks, the irradiation efficiency was equal to or higher than that of the blank without the wound coil. The risk regarding safety was reduced accordingly, indicating that the present device with the wound metal tube coil can be applied. Also, in the test of the 200 ml Erlenmeyer flask, the result was an irradiation efficiency ratio of 1.0 with two turns of the coil, indicating that the efficiency is equal to or higher with two or more turns of the coil. Similar to the beaker type, in the Erlenmeyer flask as well, the experimental scale can be selected according to the purpose from 100 ml to 500 ml, and the degree of freedom for consideration can be increased.

Example

[0054] As a round-bottom flask type device with a wound coil in Fig. 1(c), first, a device with a wound coil was fabricated in a 500 ml eggplant flask. 400 g of water was put into the eggplant flask, which was placed at the center of the μReactor storage. The inlet and outlet metal tubes were passed through the metal in patterns A to C shown in Fig. 2 and connected to both ends of the coil through the metal. As shown in Fig. 2, the body ground was taken at the root of the cylinder hole, and the outside of the cylinder hole was shielded with aluminum foil. While stirring with a magnetic stirrer, microwave of 200 W was irradiated for 20 minutes, and the temperature change was monitored with a thermocouple. 400 g of water was similarly put into a 500 ml eggplant flask without a wound coil, and while stirring with a magnetic stirrer, microwave of 200 W was irradiated for 20 minutes, and the temperature change was monitored with a thermocouple to compare the temperature rise amount ΔT. The coil specifications and experimental conditions were shown in the upper part of Table 5.

[0055] The transition of the temperature rise amount ΔT of these tests is shown in Fig. 6. In Fig. 6, in the case of Pattern A passing through the cylindrical hole in the transverse wall and Pattern C passing through the cylindrical holes in the transverse wall and the upper part, the temperature rise amount ΔT became larger than that of the blank without winding the coil. In Pattern B passing through the upper cylindrical hole, it became smaller than the blank, but in Pattern D with one additional ground connection, the temperature rise amount ΔT became larger than the blank.

[0056] Based on these temperature rise amounts ΔT, the test results of calculating the irradiation efficiency ratio with the irradiation efficiency of the blank set to 1.0 are shown in the lower part of Table 5. Looking at the irradiation efficiency ratio with respect to the blank according to the temperature standard, in Pattern B with a metal tube passing through the upper cylindrical hole, the irradiation efficiency ratio deteriorated to 0.89, and in Pattern D with one additional ground connection, it improved to 1.05. Comparing each irradiation efficiency ratio, "Pattern C > Pattern A > Pattern D > blank > Pattern B" was confirmed. From this, it was found that in a 500 ml eggplant flask of the round-bottom flask type, similar to the Erlenmeyer flask type, by taking two or more ground connections, the blank irradiation efficiency improves in all patterns. Table 5. Microwave irradiation test of 500 ml eggplant flask TIFF2025105312000006.tif6590

Example

[0057] As other round-bottom flask types, in the 500 ml eggplant flask of Example 5, under the conditions of Pattern A (both the inlet and outlet metal tubes pass through the cylindrical holes in the transverse wall of the microwave device) with good improvement in irradiation efficiency, in a 500 ml three-necked flask, 300 ml, and 200 ml eggplant flasks, with the device specifications and test conditions shown in Table 6, while stirring using a magnetic stirrer, a microwave irradiation test was conducted and the temperature transition was monitored. In each type and capacity of round-bottom flask, a microwave irradiation test of the blank without winding the coil was conducted and the temperature rise amount ΔT was compared. Example 6-1: 500 ml three-necked flask (coil with a pipe diameter of 6 mm); Pattern A Example 6-2: 300 ml eggplant flask (coil with a tube diameter of 6 mm); Pattern A Example 6-3: 200 ml eggplant flask (coil with a tube diameter of 6 mm); Pattern A

[0058] Similar to the case of Example 5, the specifications of the coils of each device and the test conditions are shown in the upper part of Table 6. Based on the respective temperature rise amounts ΔT, the irradiation efficiencies and irradiation efficiency ratios were calculated based on the time standard and temperature standard in the lower part of Table 6. The test results of the 500 ml eggplant flask in Example 5 were also included in Table 6. TIFF2025105312000007.tif12571

[0059] In Pattern A where the inlet and outlet metal tubes both pass through the cylindrical holes in the side wall of the microwave device using a 500 ml three-necked flask, 300 ml, and 200 ml eggplant flasks, the irradiation efficiency ratios were all 1.0 or more in all cases. By placing the device with the wound coil, the irradiation efficiency of the microwave was improved, and the same results as those of the beaker type and Erlenmeyer flask type were obtained.

Examples

[0060] As a test tube type device with a wound coil in Fig. 1(d), a device with a wound coil was fabricated in a 50 ml test tube. 50 g of water was put into the test tube, and this was placed at the center of the interior of the μReactor. The inlet and outlet metal tubes were passed through in Patterns A to C shown in Fig. 2 and connected to both ends of the coil of the device via the metal. As shown in Fig. 2, the body ground was taken at the base of the cylindrical hole, and the outside of the cylindrical hole was shielded with aluminum foil. While stirring with a magnetic stirrer, microwave irradiation of 50 W was performed for 20 minutes, and the temperature change was monitored with a thermocouple. 50 g of water was similarly put into a 50 ml test tube without a wound coil, and while stirring with a magnetic stirrer, microwave irradiation of 50 W was performed for 20 minutes, and the temperature change was monitored with a thermocouple to compare the temperature rise amount ΔT.

[0061] The transition of the temperature rise amount ΔT in these tests is shown in Fig. 7. In Fig. 7, in Pattern A where the metal tubes pass through the cylindrical holes in the transverse wall and Pattern C where the metal tubes pass through the cylindrical holes in the transverse wall and the upper part, the temperature rise amount ΔT was larger than that of the blank. However, in Pattern B where the metal tubes pass through the upper cylindrical holes, the temperature rise amount ΔT was smaller than that of the blank. In Pattern D where the main body grounding was taken from one location at the coil end and there were three locations for the main body grounding in Pattern B where both metal tubes passed through the upper cylindrical holes, the temperature rise amount ΔT increased compared to the blank.

[0062] Based on these temperature rise amounts ΔT, the test results of calculating the irradiation efficiency and the irradiation efficiency ratio are shown in the lower part of Table 7. Even in the 50 ml test tube of the test tube type "Pattern C > Pattern A > Pattern D > blank > Pattern B" was obtained. Here, Pattern C had the most improved irradiation efficiency and was extremely high at 2.73 in terms of the irradiation efficiency ratio based on the temperature standard. Looking at this in terms of irradiation efficiency, the microwave irradiation efficiency of the blank without the tube coil was extremely low at about 14%. The inner diameter of the 50 ml test tube is 25 mm, indicating that the load body is thin and the microwave cannot hit it efficiently. However, it was found that in the device with the tube coil wound around this test tube, the microwave can be efficiently taken into the load body. Table 7. Microwave Irradiation Test of 50 ml Test Tube Device TIFF2025105312000008.tif7090

Example

[0063] As other test tube types, under the conditions of Pattern A (both the input and output metal tubes pass through the cylindrical holes in the transverse wall of the microwave device), in a 100 ml test tube, a microwave irradiation test was conducted while stirring with a magnetic stirrer under the device specifications and test conditions shown in Table 8, and the temperature transition was monitored. A microwave irradiation test was conducted on the blank without the coil wound around the same 100 ml test tube, and the temperature rise amount ΔT was compared.

[0064] The 50-ml test tubes of Example 7 were also listed in Table 8, and the test results of the test tube type were summarized. The coil specifications and test conditions of each device are shown in the upper part, and in the lower part of Table 8, based on the temperature rise amount ΔT of each, the irradiation efficiency and irradiation efficiency ratio were calculated with respect to the time standard and temperature standard.

[0065] The 50-ml test tubes tested this time had an outer diameter of 25 mm, and the 100-ml test tubes had an outer diameter of 40 mm. It was confirmed that in test tube types such as thin test tubes and sample bottles with an outer diameter of 50 mm or less, the irradiation efficiency can be improved even when a coil is wound. Reducing the risk regarding safety in these test tube types and enabling use as an external temperature control device is very useful especially in cultures and the like where experiments using test tubes are often conducted. Until now, various contrivances have been made for experiments, such as using a temperature control device using a refrigerant such as hexane or kerosene, reducing the capacity with an air-cooling device, minimizing the microwave output as much as possible, or performing intermittent irradiation. However, there have been cases where the risk regarding safety such as refrigerant leakage is high, or there is no environment where a microwave with sufficient output can be irradiated. By adopting this technology, experiments with sufficient microwave output and continuous irradiation can usually be conducted using the instruments used in cultures and the like. Table 8. Microwave Irradiation Test of Test Tube Type Device TIFF2025105312000009.tif7074

[0066] Using a 200 ml beaker, a 300 ml Erlenmeyer flask, a 100 ml Erlenmeyer flask, and a 50 ml test tube, under the conditions of Pattern A (both the inlet and outlet metal tubes pass through the cylindrical holes in the side wall of the microwave device) similar to each example, cover the metal tube on the outlet side of the inlet and outlet metal tube parts with a resin tube so that the body grounding cannot be achieved. As one body grounding point for the metal tube part on the inlet side, while stirring using a magnetic stirrer under the same test conditions, a microwave irradiation test was conducted, and the temperature change was monitored. Figure 8 shows the results of the temperature change ΔT due to microwave irradiation for the 50 ml test tube with two body grounding points, one body grounding point, and a blank without a coil wound. Also, the similar test results for the 200 ml beaker, 300 ml Erlenmeyer flask, and 100 ml Erlenmeyer flask are summarized in Table 9.

[0067] Among these test results, the change in the temperature rise amount ΔT during microwave irradiation when the number of grounding points of the 50 ml test tube was changed from one to two is shown in Figure 8. Also, for all these comparative examples, the temperature rise rate was obtained from the temperature rise amount ΔT, and the irradiation efficiency and irradiation efficiency ratio were calculated and summarized in Table 9. From these results, it was found that in all cases, when the number of grounding points was changed from two to one, the temperature rise amount decreased and the irradiation efficiency deteriorated. That is, it was found that simply having one grounding point may not satisfy the requirement of achieving an irradiation efficiency equal to or higher than that of the blank without a coil wound as an external temperature control device with a coil wound in this technology.

[0068] Also, at one point of the ground, it is conceivable that the potential difference between the incoming metal pipe part and the outgoing metal pipe part where the ground is taken will be the highest, and the risk of arc generation will also increase. In this case, when the microwave output is in the range of 50 to 200 W with continuous irradiation, no arc generation occurred. However, for example, in a general 750 W microwave oven, when the output is set to 200 W, intermittent irradiation is performed, such as outputting 750 W for 8 seconds and then stopping for 22 seconds. Therefore, when the microwave is output at 750 W, it is considered that the risk of arc generation increases. Further considering the application of this technology to a high-power multi-mode microwave heating device, it is essential to reduce the risk of arc generation, and it is required to have two or more grounding points to eliminate this potential difference. TIFF2025105312000010.tif13880

[0069] (Isothermal Test) In Examples 1 to 8 conducted so far, an external temperature control device with a coil wound inside the multi-mode microwave irradiation apparatus was placed for a microwave irradiation test. It was confirmed that there is an effect of improving the irradiation efficiency of microwaves and that the risk of unexpected arc generation and the like can be reduced. Next, in order to actually use this apparatus as an external temperature control device by flowing a refrigerant or a heat medium through the coil tube, a beaker type, an Erlenmeyer flask type, a round-bottom flask type, and a test tube type were subjected to an isothermal test with continuous microwave irradiation to check whether they can be controlled at a desired temperature. The coils wound around each reaction vessel were the same as those tested in Examples 1 to 8. The specifications of the coils are shown in Table 2 for the beaker type, Table 4 for the Erlenmeyer flask type, Table 6 for the round-bottom flask type, and Table 8 for the test tube type, respectively. Here, in order to confirm the effect of only the temperature control device, in order to improve the cooling efficiency, a resinous heat transfer body that increases heat transfer can be used to closely attach the coil and the container, or the coil outer surface can be covered with a resin or glass fiber that transmits microwaves for heat insulation. However, in this experiment, no such measures were taken. However, in the test to confirm the effect of heat insulation and when the cooling water was flowing at 8°C or lower, condensation became severe, and since this condensation affected the test results, the test was conducted after simply insulating the device with the coil wound and the metal parts inside the chamber using experimental paper towels. As an external temperature control device, tests were conducted and confirmed regarding, first, the influence of the microwave output, second, the influence of the coil tube diameter, third, the influence of the presence or absence of heat insulation, fourth, the influence of the temperature of the medium flowing through the tube, and finally, measures for shortening the time to reach the target isothermal state by using a heat medium and a refrigerant in combination.

Example

[0070] (Effect of microwave output) As each type of container, beakers of 1000 ml, 500 ml, and 300 ml, Erlenmeyer flasks of 500 ml and 300 ml, a 500 ml eggplant flask, and test tubes of 50 ml and 100 ml were used. Water, which is a load corresponding to the capacity of each container, was put in each. As an external temperature control device, through the cylindrical holes in the transverse wall for the inlet and outlet metal tubes (Pattern A), grounding was taken from each metal tube at the base of the cylindrical holes to the main body ground, and both ends of the coil and these metal tubes were connected using resin tubes so that the refrigerant would not leak. Aluminum foil was used as a connection means through the metal, and while covering the resin tube, the metal tube and the coil end were connected. Tap water was used as the refrigerant, and in each container, the output of the microwave was changed and continuous irradiation was performed. When a constant temperature state was reached, the state was maintained for 30 minutes or more.

[0071] As an example of the temperature transition of these constant temperature tests, the test results using a 500 ml beaker are shown in Fig. 9. Also, the conditions and results of the constant temperature tests for these beaker types, Erlenmeyer flask types, round bottom flask types, and test tube types are shown in Table 10. It was confirmed that in all types, a constant temperature state of ±1.0 °C could be maintained for 30 minutes or more at the reached temperature according to the output of the microwave. Table 10. Constant temperature test results under microwave irradiation (effect of output) TIFF2025105312000011.tif8290

Example

[0072] (Effect of coil pipe diameter) Using a 100 ml beaker, an apparatus with the coil pipe diameter of the copper pipe coil changed to 2 mm, 3 mm, and 4 mm and the same number of turns (see Table 2) was filled with 100 g of water. Similar to Example 9, an external temperature control device was assembled by passing the inlet and outlet metal tubes through the cylindrical holes in the transverse wall (Pattern A). Under the same conditions where water at 10 °C was flowed at 60 ml / min as the refrigerant, a constant temperature test was performed with continuous irradiation at 30 W of microwave.

[0073] The temperature change during this isothermal test is shown in Fig. 10. With a coil having a pipe diameter of 4 mm, the temperature was 44.0 ± 1.0 °C; with a coil having a pipe diameter of 3 mm, the temperature was 45.5 ± 1.0 °C; and with a coil having a pipe diameter of 2 mm, the temperature was 48.0 ± 1.0 °C. In all cases, the isothermal state could be maintained for 30 minutes or more. In this test, the same amount of refrigerant flowed at 60 ml / min in all the coils of 2 mm, 3 mm, and 4 mm, and the difference was within 4 degrees, indicating that there was almost no difference in the heat removal capacity. It was confirmed that coils with a pipe diameter of 2 mm or more could be used as an external temperature control device.

Example

[0074] (Presence or absence of heat insulation) Next, in order to confirm the effect of heat insulation, a test was conducted to see if there would be a difference in the temperature that could be maintained with or without heat insulation under the same conditions. Using a 100-ml Erlenmeyer flask, 100 g of water was put in, and an external temperature control device was assembled in the same way as in Example 9, i.e., by passing a metal pipe for insertion and extraction through a cylindrical hole in the lateral wall (Pattern A). Tap water used as the refrigerant was heated to 10 °C through a heat exchanger, and a test was conducted on the change in the presence or absence of heat insulation. First, with no heat insulation, microwave irradiation at 50 W was continuously applied to maintain the isothermal state for 30 minutes or more. Then, simple heat insulation was applied by covering the whole with experimental paper towels from the outside of the temperature control device, and a test with heat insulation was conducted by continuously irradiating the same microwave output of 50 W.

[0075] The temperature change during the isothermal test with or without heat insulation is shown in Fig. 11. The temperature of the water was 62.4 ± 1.0 °C when there was no heat insulation. Then, without changing the flow rate and temperature of the refrigerant, the whole Erlenmeyer flask and coil were covered with experimental paper towels for simple heat insulation, and the temperature became 51.7 ± 1.0 °C, and this isothermal state could be maintained for 40 minutes or more. It was confirmed that with continuous irradiation of 50 W of microwaves, under the same test conditions where the temperature and flow rate of the refrigerant were the same, heat insulation could achieve an isothermal state with a temperature drop of 10.7 °C. The effect of heat insulation could also be confirmed with simple heat insulation by wrapping the outside with paper towels. It is considered that if construction is carried out to further increase the heat insulation efficiency, this effect can be further enhanced.

Example

[0076] (Effect of refrigerant temperature) Using a 200 ml Erlenmeyer flask, 200 g of water was added, and it was assembled in the same manner as in Example 9 by passing the external temperature control device through the metal tube that enters and exits the cylindrical hole in the lateral wall (Pattern A). Tap water was used as the refrigerant, and by passing it through the heat exchanger, the temperature was changed to 27 °C and 13 °C without changing the flow rate, and a constant temperature test was conducted with continuous irradiation of 100 W of microwave.

[0077] The temperature change during this constant temperature test is shown in Fig. 12. When the temperature of the tap water as the refrigerant was 27 °C at room temperature, this state was maintained at 60.2 ± 1.0 °C for 37 minutes with continuous irradiation of microwave. Then, when the temperature of the refrigerant was changed to 13 °C, a constant temperature state could be maintained at 41.2 ± 1.0 °C for 40 minutes. It was confirmed that by changing the temperature of the refrigerant, a constant temperature state with a change of nearly 20 °C could be maintained under continuous irradiation of the same microwave output.

Example

[0078] (Combined test of refrigerant / heat medium) Using a 300 ml Erlenmeyer flask, 300 g of water was added, and it was assembled in the same manner as in Example 9 by passing the external temperature control device through the metal tube that enters and exits the cylindrical hole in the lateral wall (Pattern A). A constant temperature test was conducted with continuous irradiation of 50 W of microwave, comparing the time from room temperature to the constant temperature state for the case of only the refrigerant and the case of using both the heat medium and the refrigerant. Run1: While flowing 60 ml / min of 26 °C refrigerant in the coil tube, the time was measured until the water of the load in the container reached a constant temperature state with continuous irradiation of 50 W of microwave. Run2: While flowing 60 °C heat medium in the coil tube until the water of the load in the container reached nearly 50 °C with continuous irradiation of microwave from room temperature, the time was measured until the heat medium was changed to refrigerant and a constant temperature state was reached.

[0079] The results of the isothermal test of microwave irradiation with combined use of heat medium / refrigerant are shown in Fig. 13. In Run1, which was tested only with refrigerant at 26°C, it took 93 minutes to reach the isothermal state of 54°C. In Run-2, while irradiating with 50 W of microwave, when the heat medium at 60°C was flowing until it reached 48°C from room temperature, and then the refrigerant was switched to 20°C and microwave irradiation was continued, it reached the isothermal state in 43 minutes. By using the heat medium and refrigerant in combination, the time to reach the isothermal state could be shortened to less than half.

[0080] When performing reactions or cultures using microwaves, it is necessary to reach the isothermal state quickly in order to obtain the effects of microwaves. In the test results this time, the isothermal state could be achieved in 43 minutes. However, to further shorten the time to reach the isothermal state, (1) delay the timing of switching the heat medium to the refrigerant. Here, the switch was made at 48°C, but it can be further shortened by switching at 52 - 54°C. (2) Raise the temperature of the heat medium further. Here, a heat medium at 60°C was used, but for example, if a heat medium at 90°C is used, the heating rate can be shortened accordingly. (3) By combining (1) and (2) above, the time can be further shortened. (4) Before starting microwave irradiation, heat up the medium to a state close to the set temperature using the heat medium, then switch to the refrigerant and start microwave irradiation, so that only the influence of microwave irradiation can be confirmed. (5) It is also conceivable to raise the temperature with microwaves, for example, with a microwave output of 200 W, and then switch to a predetermined 50 W. However, in this case, it is necessary to consider the influence of changing the microwave output midway.

[0081] Using representative reaction vessels of beaker type, Erlenmeyer flask type, round-bottom flask type, and test tube type, isothermal tests were conducted by microwave irradiation at 30 W to 150 W. In all cases, an isothermal state could be maintained at a temperature below the boiling point for 30 minutes or more. It was also confirmed that the temperature that could be maintained could be changed by changing the microwave output, and that the temperature that could be maintained could also be changed by changing the temperature of the refrigerant even at the same microwave output. And by insulating this device, it was confirmed that the efficiency of temperature adjustment was improved. When the refrigerant is set at a temperature lower than room temperature, dew condensation may occur in the metal tube due to the influence of the environment such as humidity. It is preferable to insulate with a heat insulating material that transmits microwaves.

[0082] It was demonstrated that by selecting the reaction amount and the type of reactor to react in the experiment and adjusting the microwave output, the temperature of the refrigerant, and the flow rate so as to reach the desired temperature, microwave irradiation can be performed while maintaining an isothermal state. In particular, culture tests and enzyme reactions by continuous irradiation of microwaves have been carried out by combining microscale tests by air cooling, tests by cooling using refrigerants with low microwave absorption such as hexane and kerosene, tests by reducing the volume and suppressing the microwave output, or tests by intermittent irradiation of microwaves. By using this technology, it is very useful for future research and development in this field that microwave irradiation tests can be conducted under the same conditions as normal tests without considering the limitations related to these tests. Furthermore, since there is no restriction on the medium flowing through the coil tube, in high-temperature reactions under microwave irradiation using an organic solvent, it is possible to safely test an isothermal state below the boiling point of the solvent while considering heat dissipation by utilizing an appropriate heat transfer medium, which is considered to be useful for analyzing the reaction mechanism by microwave irradiation and the like.

Industrial Applicability

[0083] Since a coiled temperature control device can be fabricated according to the size of the reaction vessel, it is a technology applicable from small-scale experiments on a beaker scale to large-scale industrial devices. Also, regardless of the type of refrigerant or heat medium, and since the temperature control system can be simplified, its scope of application is expanded. In particular, in culturing, industrially, it is required to scale up from test tube level, starting with the growth of bacteria, etc., to scales of several liters, several hundred liters, and several cubic meters. If there is a multi-mode microwave irradiation device with a housing size corresponding to microwave irradiation for these scales, there is a possibility that it can be applied to them.

[0084] Regarding culturing and enzyme reactions, there are few suitable temperature control devices that can be safely and easily applied, which has been an obstacle to the advancement of research on culturing and enzyme reactions using microwaves. If a precision temperature control device for high-efficiency microwave irradiation using a metal tube coil is utilized, the temperature control device can be made simple and streamlined, and research using microwaves can be conducted under conditions similar to culturing and enzyme reactions performed in commonly used containers for experiments. By being able to compare normal culturing with culturing using microwaves, it is considered that research on the use of microwaves in this field will be promoted.

[0085] A microwave oven, which is representative of a multi-mode microwave irradiator, is a highly versatile device that can be obtained relatively inexpensively. However, generally, it is mainly used as a heating device using microwaves, and the mainstream of research is mainly single-mode research using a small number of reaction vessels or flow-type reaction vessels. Considering practical application, research on multi-mode microwave irradiation devices is very useful because the amount of reaction can be increased and an inexpensive microwave irradiation device can be used. Also, introducing metal into a multi-mode microwave irradiation device has risks such as arc generation and abnormal heating of the magnetron, and has been considered an item to be avoided. However, by using the precision temperature control device for high-efficiency microwave irradiation using the metal tube coil of the present invention, a highly versatile multi-mode microwave irradiation device typified by a microwave oven can provide many research opportunities such as reactions and culturing. Furthermore, when the boiling point of the reaction solvent is high, by using the precision temperature control device for high-efficiency microwave irradiation using this metal tube coil that can efficiently irradiate the reaction vessel with microwaves, heat insulation can be achieved to maintain a high temperature, and the thickness of the heat insulation for preventing heat dissipation from the reactor can be reduced, and a simpler system can maintain a high-temperature state.

Claims

1. In a multi-mode microwave heating apparatus that irradiates a load with microwaves to heat it, a device in which a metal tube is wound in a coil shape along the outside of a reaction vessel that transmits microwaves is placed inside the apparatus. The metal tube used for introducing / discharging a refrigerant or a heat medium passes through a cylindrical hole provided in the lateral wall or the upper part of the multi-mode microwave apparatus. Grounding is taken from both ends of this metal tube or coil to the main body, and both ends of the coil wound around the container are connected to this metal tube via metal, so that a refrigerant or a heat medium can flow through the metal tube coil wound around this reaction vessel. It is a device characterized by having such a structure. As a reaction vessel that transmits microwaves, it is characterized in that it can correspond to beaker type, Erlenmeyer flask type, round bottom flask type, and test tube type with a narrow diameter, and various types of reaction vessel shapes. It is a device characterized in that irradiation efficiency equal to or higher than that of a reaction vessel without a wound coil can be obtained, that is, microwave absorption is improved. Furthermore, the refrigerant or heat medium passed through the metal tube coil of this device can select various refrigerants suitable for achieving desired temperature conditions regardless of the presence or absence of microwave absorption. It is a precision temperature control device for high-efficiency microwave irradiation using a metal tube coil.

2. In the precision temperature control device for high-efficiency microwave irradiation using the metal tube coil according to Claim 1, where the reaction vessel body is made of a material that transmits microwaves and a coil of a metal tube is wound along the outside of this reactor, the material of the metal tube can be one generally used as a metal tube, such as copper, SUS, aluminum, etc. The tube diameter of the metal tube coil is 2 mm or more, the coil is wound more than 2 turns, and the interval between coils is 4 mm or more. It is characterized in that main body grounding is taken from two or more points of each of the metal tubes used for introducing / discharging a refrigerant or a heat medium, or each of both ends of the coil, and the metal tube and the coil part are connected via metal. This connection via metal is not limited to joints using metal ferrules, but after connecting with a tube made of resin or the like that can withstand the flowing refrigerant or heat medium so that the refrigerant liquid or heat medium liquid does not leak, the introduction / discharge metal tube and the coil end part may be connected with a metal wire or a metal plate, etc.

Images