Freeze Dryer

Abstract

The present application relates to the field of freeze-drying technology, and discloses a freeze dryer, including a refrigerant circulation loop, a shell and tube heat exchanger, a bypass pipeline and a control valve, wherein the refrigerant circulation loop is formed by connecting a compressor, a condenser, a throttling device and an evaporator in sequence through a refrigerant pipe; the shell and tube heat exchanger is constructed with a first refrigerant flow channel and a second refrigerant flow channel, the refrigerant flowing from the condenser to the throttling device flows through the first refrigerant flow channel, and the refrigerant flowing from the evaporator to the compressor flows through the second refrigerant flow channel; the bypass pipeline has a first end connected to the first refrigerant pipe between the condenser and the throttling device, and a second end connected to the second refrigerant pipe between the throttling device and the evaporator; the control valve is arranged on the bypass pipeline. Using the freeze dryer disclosed in the present application, the return air temperature of the compressor can be reduced during defrosting, thereby increasing the service life of the compressor.

Description

Technical Field

[0001] This application relates to the field of freeze-drying technology, for example to a freeze dryer. Background Art

[0002] The freeze dryer contains a cold trap, which creates a low-temperature environment to capture water vapor sublimating from the frozen object. After the freeze dryer finishes its operation, the cold trap needs to be defrosted. If defrosting is done using electric heating, it not only complicates the structure of the cold trap but also wastes electrical energy.

[0003] To simplify the structure of the freeze dryer and defrost the cold trap more energy-efficiently, a freeze dryer refrigeration device with defrosting function is disclosed in the related technology, including a compressor, a condenser, a capillary tube, an evaporator and a bypass pipeline. The high-temperature gas discharged from the compressor is guided to the evaporator through the bypass pipeline to defrost the cold trap.

[0004] In the process of implementing the embodiments of this disclosure, at least the following problems were found in the related art:

[0005] The temperature of the refrigerant discharged from the compressor is relatively high, and the temperature of the high-temperature refrigerant cannot be effectively reduced after passing through the evaporator. This will cause the return air temperature of the compressor to be relatively high, thus affecting the service life of the compressor.

[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0007] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments, but rather as a prelude to the detailed description that follows.

[0008] This disclosure provides a freeze dryer to reduce the return gas temperature of the compressor when defrosting a cold trap.

[0009] In some embodiments, the freeze dryer includes a refrigerant circulation loop, a shell-and-tube heat exchanger, a bypass pipeline, and a control valve. The refrigerant circulation loop is formed by sequentially connecting a compressor, a condenser, a throttling device, and an evaporator via refrigerant pipes. The shell-and-tube heat exchanger has a first refrigerant flow channel and a second refrigerant flow channel. Refrigerant flowing from the condenser to the throttling device flows through the first refrigerant flow channel, and refrigerant flowing from the evaporator to the compressor flows through the second refrigerant flow channel. The bypass pipeline has a first end connected to the first refrigerant pipe between the condenser and the throttling device, and a second end connected to the second refrigerant pipe between the throttling device and the evaporator. The control valve is disposed on the bypass pipeline.

[0010] In some embodiments, the bypass line is connected in parallel to the throttling device.

[0011] In some embodiments, the bypass line is connected in parallel to the throttling device and the first refrigerant flow path of the shell-and-tube heat exchanger.

[0012] In some embodiments, the shell and tube heat exchanger includes an inner tube and an outer tube, the interlayer between the inner tube and the outer tube is a first refrigerant flow channel, and the interior of the inner tube is a second refrigerant flow channel.

[0013] In some embodiments, the freeze dryer further includes a temperature sensor and a control unit, wherein the temperature sensor is used to acquire the return gas temperature of the compressor; and the control unit is configured to control the opening degree of the control valve according to the return gas temperature of the compressor during defrosting.

[0014] In some embodiments, the freeze dryer further includes a fan, which is configured to reduce the temperature of the condenser.

[0015] In some embodiments, the condenser is a microchannel condenser.

[0016] In some embodiments, the control unit is further configured to control the fan speed based on the return gas temperature of the compressor.

[0017] In some embodiments, the freeze dryer further includes a cold trap with a freezing space, and the evaporator includes heat exchange tubes wound in a spiral shape in the freezing space to enclose a freezing area.

[0018] In some embodiments, the freeze dryer further includes a drying chamber, a shelf, and a heating device, wherein the drying chamber is located above the cold trap, the bottom of the drying chamber has a communicating window, and the cold trap is connected to the communicating window through an opening at the top; the shelf can be raised and lowered between the drying chamber and the cold trap; and the heating device is disposed in the drying chamber.

[0019] In some embodiments, the shell-and-tube heat exchanger is disposed below the cold trap.

[0020] The freeze dryer provided in the embodiments of the present disclosure can achieve the following technical effects:

[0021] 1. During refrigeration, the temperature of the refrigerant entering the throttling device and evaporator can be reduced by using a shell-and-tube heat exchanger, thereby allowing the refrigerant to evaporate and absorb heat in an orderly manner in the evaporator, thus improving the efficiency of the evaporator;

[0022] 2. During cooling, the return air temperature of the compressor can be increased through the shell and tube heat exchanger, so that the return air temperature of the compressor is in the appropriate temperature range, improving the smoothness of the compressor operation;

[0023] 3. Set up a bypass line. During defrosting, the refrigerant discharged from the compressor first enters the condenser for cooling and then enters the evaporator through the bypass line. This can reduce the temperature of the refrigerant returning to the compressor to avoid overheating of the compressor.

[0024] 4. During defrosting, the refrigerant flows through the condenser and evaporator as well as the first and second refrigerant flow channels of the shell and tube heat exchanger, which helps the compressor establish a stable suction and exhaust pressure difference, so that the compressor can run more smoothly;

[0025] 5. A control valve is installed in the bypass pipeline to easily switch between the refrigeration mode and defrosting mode of the freeze dryer.

[0026] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description

[0027] One or more embodiments are exemplarily described by corresponding drawings. These exemplary descriptions and drawings do not limit the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements. The drawings do not constitute a scale limitation. In addition,

[0028] Figure 1 This is a schematic diagram of the structure of a freeze dryer provided in an embodiment of this disclosure;

[0029] Figure 2 This is a schematic diagram of another freeze dryer provided in an embodiment of this disclosure;

[0030] Figure 3 This is a schematic diagram of another freeze dryer provided in an embodiment of this disclosure;

[0031] Figure 4 This is a schematic diagram of a freeze dryer with the shell and drying chamber removed, provided in an embodiment of this disclosure;

[0032] Figure 5 This is a cross-sectional schematic diagram of a freeze dryer provided in an embodiment of this disclosure;

[0033] Figure 6 This is a schematic diagram of the structure of a cold trap for a freeze dryer provided in an embodiment of this disclosure.

[0034] Reference numerals:

[0035] 100: cabinet; 110: compressor; 120: condenser; 121: fan; 130: throttling device; 140: evaporator; 200: shell and tube heat exchanger; 210: first refrigerant flow channel; 220: second refrigerant flow channel; 310: bypass line; 320: control valve; 410: drying chamber; 411: heating device; 412: storage rack; 420: cold trap. Detailed Implementation

[0036] In order to be able to understand the features and technical content of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure is described in detail below in conjunction with the accompanying drawings. The accompanying drawings are for reference only and are not used to limit the embodiments of the present disclosure. In the following technical description, for the sake of convenience of explanation, a full understanding of the disclosed embodiments is provided through multiple details. However, one or more embodiments can still be implemented without these details. In other cases, to simplify the drawings, well-known structures and devices can be simplified for display.

[0037] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0038] In this disclosure, the terms "upper," "lower," "inner," "middle," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for better description of the embodiments of this disclosure and their implementations, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to require them to be constructed and operated in a specific orientation. Furthermore, some of the aforementioned terms may be used to indicate other meanings besides orientation or positional relationship; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in the embodiments of this disclosure according to the specific circumstances.

[0039] Furthermore, the terms "set up," "connect," and "fix" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0040] Unless otherwise stated, the term "multiple" means two or more.

[0041] In this embodiment of the disclosure, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.

[0042] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0043] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present disclosure can be combined with each other.

[0044] Combine Figure 1-6 As shown, this embodiment of the present disclosure provides a freeze dryer, including a refrigerant circulation loop, a shell-and-tube heat exchanger 200, a bypass pipe 310, and a control valve 320. The refrigerant circulation loop is formed by sequentially connecting a compressor 110, a condenser 120, a throttling device 130, and an evaporator 140 via refrigerant pipes. The shell-and-tube heat exchanger 200 is configured with a first refrigerant flow channel 210 and a second refrigerant flow channel 220. Refrigerant flowing from the condenser 120 to the throttling device 130 flows through the first refrigerant flow channel 210, and refrigerant flowing from the evaporator 140 to the compressor 110 flows through the second refrigerant flow channel 220. The bypass pipe 310 has a first end connected to the first refrigerant pipe between the condenser 120 and the throttling device 130, and a second end connected to the second refrigerant pipe between the throttling device 130 and the evaporator 140. The control valve 320 is disposed on the bypass pipe 310.

[0045] Freeze dryers dehydrate objects by creating a low-temperature environment that condenses water into fixed water and a vacuum environment that causes the solid water to sublimate. In freeze dryers, the evaporator is located in a relatively small and enclosed space, limiting the amount of heat it can remove during refrigeration, which can easily lead to excessively low compressor return gas temperatures. Similarly, during defrosting, the amount of heat released by the refrigerant in the evaporator is limited, which can easily lead to excessively high compressor return gas temperatures. The compressor return gas temperature needs to be maintained within a suitable range; temperatures that are too high or too low are detrimental to the stable operation of the compressor.

[0046] In this embodiment, a low-temperature environment is created through a refrigerant circulation loop. Specifically, the refrigerant circulation loop includes a compressor 110, a condenser 120, a throttling device 130, and an evaporator 140. Gaseous refrigerant enters the compressor 110, is compressed into a high-temperature, high-pressure gaseous refrigerant, and then enters the condenser 120 through the exhaust gas of the compressor 110. The high-temperature, high-pressure refrigerant cools down in the condenser 120, and then enters the evaporator 140 in liquid form through the throttling device 130, where it evaporates and absorbs heat to become gaseous refrigerant again, then returns to the compressor 110 from the return gas end. When the refrigerant evaporates in the evaporator 140, it absorbs a large amount of heat, thereby lowering the temperature of the condenser 120. The refrigerant circulates among the compressor 110, condenser 120, throttling device 130, and evaporator 140, continuously lowering the temperature of the condenser 120 and providing a low-temperature environment for the object being frozen.

[0047] The freeze dryer also includes a shell-and-tube heat exchanger 200, which has a first refrigerant flow channel 210 and a second refrigerant flow channel 220. The refrigerant flowing through the first refrigerant flow channel 210 and the refrigerant flowing through the second refrigerant flow channel 220 exchange heat through the shell-and-tube heat exchanger 200.

[0048] Specifically, the refrigerant flowing from the condenser 120 to the throttling device 130 flows through the first refrigerant flow channel 210, while the refrigerant flowing from the evaporator 140 to the compressor 110 flows through the second refrigerant flow channel 220. The refrigerant flowing from the condenser 120 to the throttling device 130 is at a higher temperature, while the refrigerant flowing from the evaporator 140 to the compressor 110 is at a lower temperature. Heat is exchanged between the two refrigerant channels via the shell-and-tube heat exchanger 200. The temperature of the refrigerant flowing from the condenser 120 to the throttling device 130 is lowered, which allows the refrigerant entering the evaporator to achieve a certain degree of subcooling, thereby facilitating heat absorption during evaporation in the evaporator 140. The temperature of the refrigerant flowing from the evaporator 140 to the compressor 110 is raised, thereby increasing the return air temperature from the compressor 110. It should be noted that in a freeze dryer, the amount of heat required by the evaporator 140 to create a low-temperature environment is relatively limited. Therefore, the temperature of the refrigerant flowing out of the evaporator 140 is relatively low. The return air temperature from compressor 110 needs to be maintained within a relatively suitable range. If the refrigerant temperature returning to compressor 110 is too low, compressor 110 may malfunction due to poor lubrication or other reasons. Installing a double-tube heat exchanger 200 to increase the return air temperature from compressor 110 allows for continuous cooling of the refrigerant circulation loop. Lowering the temperature of the refrigerant entering evaporator 140 allows the refrigerant to achieve a certain degree of subcooling, allowing the refrigerant to evaporate in an orderly manner within evaporator 140 and improving the stability of the refrigerant circulation system.

[0049] The refrigerant pipe between the condenser 120 and the throttling device 130 is the first refrigerant pipe, and the refrigerant pipe between the throttling device 130 and the evaporator 140 is the second refrigerant pipe. In some cases, the first refrigerant flow channel 210 of the double-tube heat exchanger 200 serves as a portion of the first refrigerant pipe. The bypass line 310 is connected to the first refrigerant pipe at its first end and to the second refrigerant pipe at its second end. When the bypass line 310 is in the open state, the suction and exhaust pressure difference of the compressor 110 is reduced, the refrigerant flow rate is increased, and the high-temperature gaseous refrigerant flowing out of the compressor 110 takes less time to pass through the condenser 120. Therefore, when it flows out of the condenser 120, its temperature is sufficient for defrosting. The refrigerant entering the evaporator 140 releases heat, its temperature is reduced, and it flows through the second refrigerant flow channel 220 of the double-tube heat exchanger 200 before returning to the compressor 110.

[0050] With this configuration, the high-temperature gaseous refrigerant flowing from the compressor 110 is cooled by the condenser 120 before entering the evaporator 140 via the bypass pipe 310. The refrigerant entering the evaporator 140 is at a relatively low temperature, which reduces the return gas temperature of the compressor 110 while maintaining a good defrosting effect, thus improving the service life of the compressor 110. Furthermore, during defrosting, the refrigerant flowing from the compressor 110 passes through the condenser 120, the evaporator 140, and the first refrigerant flow channel 210 and the second refrigerant flow channel 220 of the shell-and-tube heat exchanger 200. This relatively long journey results in greater resistance, allowing the compressor 110 to maintain a suitable suction and discharge pressure difference, which is beneficial for the stable operation of the compressor 110.

[0051] The bypass line 310 is equipped with a control valve 320, which switches between cooling and defrosting modes. Specifically, in defrosting mode, the control valve 320 is opened, and the high-temperature refrigerant discharged from the compressor 110 flows through the condenser 120 and is then divided into two parts. The first part enters the condenser 120 through the bypass line 310 for defrosting, and the second part enters the evaporator 140 through the throttling device 130. Due to the large flow resistance of the throttling device 130, the proportion of refrigerant in the first part is much higher than that in the second part. In cooling mode, the control valve 320 is closed, and all the refrigerant passes through the throttling device 130 into the evaporator 140 to evaporate and absorb heat, thereby lowering the temperature of the evaporator 140. This configuration allows for convenient switching between the cooling and defrosting modes of the freeze dryer. It should be noted that, with the output power of the compressor 110 remaining constant, the flow rate of the refrigerant in the refrigerant circulation loop is mainly affected by the throttling resistance. Therefore, the flow rate of the refrigerant can be controlled by adjusting the opening of the control valve 320, thereby controlling the defrosting speed and the return gas temperature of the compressor 110.

[0052] When using the freeze dryer provided by the embodiment of the present disclosure, the temperature of the refrigerant entering the throttling device 130 can be reduced through the shell and tube heat exchanger 200 during refrigeration, thereby reducing the temperature of the refrigerant entering the evaporator 140. The refrigerant temperature is relatively low, and it can evaporate and absorb heat in an orderly manner in the evaporator 140, thereby improving the efficiency of the evaporator 140; the shell and tube heat exchanger 200 can also increase the return air temperature of the compressor 110, so that the return air temperature of the compressor 110 is within a suitable temperature range, improving the smoothness of the operation of the compressor 110; a bypass line 310 is provided, and during defrosting, the refrigerant discharged from the compressor 110 first enters the condenser 120 for cooling and then enters the evaporator 140 through the bypass line 310, thereby reducing the refrigerant returning to the compressor 110. The temperature of the refrigerant prevents the temperature of the compressor 110 from being too high; during defrosting, the refrigerant flows through the condenser 120 and the evaporator 140 and the first refrigerant flow channel 210 and the second refrigerant flow channel 220 of the shell and tube heat exchanger 200, which is conducive to the compressor 110 to establish a stable suction and exhaust pressure difference, so that the compressor 110 can run more smoothly; a control valve 320 is set in the bypass line 310, which can conveniently switch the refrigeration mode and defrost mode of the freeze dryer, and control the return air temperature of the compressor 110 by adjusting the valve opening of the control valve 320.

[0053] Optionally, the bypass line 310 is connected in parallel with the throttling device 130.

[0054] Combine Figure 1 As shown, bypass line 310 is connected in parallel with throttling device 130. During defrost, control valve 320 is opened, and the refrigerant flows through first refrigerant flow channel 210 of double-tube heat exchanger 200 before entering bypass line 310. First, during defrost, the refrigerant entering evaporator 140 is at a lower temperature, further reducing the temperature of the refrigerant returning to compressor 110. Second, during defrost, the refrigerant travels a longer distance, which helps compressor 110 establish a stable suction and exhaust pressure differential, thereby ensuring smooth operation of compressor 110. Furthermore, bypass line 310 is connected only in parallel with throttling device 130, and the distance between the two ends of bypass line 310 is relatively short, facilitating the installation of bypass line 310.

[0055] Optionally, the bypass line 310 is connected in parallel with the throttling device 130 and the first refrigerant flow channel 210 of the shell-and-tube heat exchanger 200.

[0056] Combine Figure 2 As shown, during defrosting, the control valve 320 is opened, and the refrigerant discharged from the exhaust of the compressor 110 flows through the condenser 120, the bypass line 310, and the evaporator 140 in sequence, and then returns to the compressor 110 through the second refrigerant flow channel 220 of the double-tube heat exchanger 200. In this case, the refrigerant does not pass through the first refrigerant flow channel 210 of the double-tube heat exchanger 200, and the resistance along the refrigerant is small, which can increase the flow rate of the refrigerant and thus the defrosting speed.

[0057] Optionally, the shell-and-tube heat exchanger 200 includes an inner tube and an outer tube, with a first refrigerant flow channel 210 between the inner and outer tubes and a second refrigerant flow channel 220 inside the inner tube.

[0058] The inner tube contains a second refrigerant channel 220, through which the refrigerant exchanges heat only with the refrigerant in the first refrigerant channel 210. The space between the inner and outer tubes is the first refrigerant channel 210, through which the refrigerant exchanges heat with the refrigerant in the second refrigerant channel and the air outside the outer tube. During refrigeration, cooling is the target product of the refrigerant circulation system, while heat is a byproduct. Cooling is beneficial to the refrigerant circulation loop, while heat is detrimental. The refrigerant in the second refrigerant channel 220 has a lower temperature, while the refrigerant in the first refrigerant channel 210 has a higher temperature. The heat carried by the refrigerant in the first refrigerant channel 210 exchanges heat with the air outside the outer tube and is then discharged into the environment of the freeze dryer. The cooling carried by the refrigerant in the second refrigerant channel 220 is retained within the refrigerant circulation loop by being transferred to the refrigerant in the first refrigerant channel 210. This configuration reduces energy consumption in the refrigerant circulation loop and improves its cooling efficiency.

[0059] Optionally, the freeze dryer also includes a temperature sensor and a control unit, wherein the temperature sensor is used to obtain the return gas temperature of the compressor 110; and the control unit is configured to control the opening degree of the control valve 320 according to the return gas temperature of the compressor 110 during defrosting.

[0060] The return gas temperature of compressor 110 is a key control target. A temperature sensor is installed to obtain the return gas temperature of compressor 110, allowing the freeze dryer to use the return gas temperature of compressor 110 as the control target for more accurate control. The control unit is electrically connected to the temperature sensor and control valve 320 and is configured to control the opening of control valve 320 according to the return gas temperature of compressor 110. Specifically, when the return gas temperature of compressor 110 is high, the opening of control valve 320 is reduced, thereby reducing the refrigerant flow rate and allowing the refrigerant entering evaporator 140 to fully release heat and lower its temperature, further reducing the return gas temperature of compressor 110; when the return gas temperature of compressor 110 is low, the opening of control valve 320 is increased, thereby increasing the refrigerant flow rate to increase the defrosting speed and increase the return gas temperature of compressor 110. This configuration allows for more accurate control of the return gas temperature of compressor 110, which is beneficial to the stable operation of compressor 110.

[0061] Optionally, the freeze dryer further includes a fan 121 , which is provided corresponding to the condenser 120 and is used to reduce the temperature of the condenser 120 .

[0062] When the freeze dryer is operating in refrigeration mode, the high-temperature refrigerant discharged from the compressor 110 dissipates heat in the condenser 120. A fan 121 is installed corresponding to the condenser 120, which drives more airflow through the condenser 120, thereby cooling the refrigerant in the condenser 120 and allowing it to enter the evaporator 140 in a liquid state after being throttled. This configuration improves the heat exchange efficiency of the condenser 120, further enhancing the refrigeration efficiency of the freeze dryer.

[0063] Optionally, the condenser 120 is a microchannel condenser.

[0064] When the channel size is less than 3 mm, the gas-liquid two-phase flow and phase change patterns will differ from those of larger channels. The smaller the channel size, the more pronounced this size effect. When the channel diameter is as small as 0.5-1 mm, the convective heat transfer coefficient can increase by 50%-100%. The condenser 120 is a microchannel heat exchanger, which can achieve strong heat exchange with a smaller refrigerant charge and smaller size. This allows for a reduction in the size of the condenser 120 and an improvement in its heat exchange efficiency. Due to the smaller refrigerant charge in the refrigerant circulation loop, a smaller compressor can be selected for the compressor 110. This facilitates the miniaturization of the freeze dryer and improves its refrigeration performance.

[0065] Optionally, the control unit is also configured to control the speed of the fan 121 based on the return gas temperature of the compressor 110.

[0066] During defrosting in the freeze dryer, the refrigerant entering the evaporator 140 first passes through the condenser 120. With the compressor 110 frequency and control valve 320 opening remaining constant, the refrigerant temperature at the condenser 120 outlet determines the compressor 110 return gas temperature. With the fan 121 rotating, its speed, to some extent, determines the refrigerant temperature at the condenser 120 outlet. Therefore, the compressor 110 return gas temperature can be indirectly controlled by adjusting the fan speed. Specifically, if the compressor 110 return gas temperature is too high, increasing the fan speed lowers the refrigerant temperature at the condenser 120 outlet, further reducing the compressor 110 return gas temperature. Conversely, if the compressor 110 return gas temperature is too low, decreasing the fan speed raises the refrigerant temperature at the condenser 120 outlet, further increasing the compressor 110 return gas temperature. This configuration allows for more accurate control of the compressor 110 return gas temperature.

[0067] Optionally, the freeze dryer also includes a cold trap 420 with a freezing space, and an evaporator 140 including heat exchange tubes wound in a spiral shape in the freezing space to enclose the freezing area.

[0068] Combine Figure 4-6As shown, the evaporator 140 includes heat exchange tubes wound in a spiral shape. This allows the evaporator 140 to have a large heat exchange area, while the spiral shape also provides a storage space for placing frozen objects. Exemplarily, the cold trap 420 has an open top for placing and removing frozen objects. The heat exchanger is spiral-shaped, with its axis facing the opening of the cold trap 420. The outer ring is close to the inner wall of the freezing space, and the inner ring is the aforementioned freezing area. When a frozen object is placed in the freezing area of ​​the evaporator, the heat carried by the freeze-dried object is transferred to the evaporator 140 through heat convection and heat radiation. This arrangement improves the freezing effect of the evaporator 140 on the frozen object and allows for the placement of larger frozen objects in the cold trap 420.

[0069] Optionally, the freeze dryer also includes a drying chamber 410, a shelf 412, and a heating device 411. The drying chamber 410 is located above the cold trap 420, and a connecting window is provided at the bottom of the drying chamber 410. The cold trap 420 is connected to the connecting window through an opening at the top. The shelf 412 can be raised and lowered between the drying chamber 410 and the cold trap 420. The heating device 411 is located in the drying chamber 410.

[0070] The freeze dryer includes a housing 100, a drying chamber 410, and a cold trap 420, all located within the housing 100. The drying chamber 410 has a connecting window at its bottom, and the cold trap 420 has an open top. The cold trap 420 is located below the drying chamber 410, with its top opening aligned with the connecting window at the bottom of the drying chamber 410. A shelf 412 is used to hold the frozen object and is height-adjustable. When dehydrating the object using the freeze dryer, the frozen object is placed on the shelf 412 and transferred to the cold trap 420. The object is frozen in the cold trap 420, and then the shelf 412 rises to transfer the frozen object to the drying chamber 410. At this time, the vacuum pump is activated, and the solid water in the freeze-dried object sublimates into gaseous water as the pressure decreases, thus achieving freeze-drying dehydration. Since the sublimation of solid water requires the absorption of heat, a heating device 411 is installed in the freeze-drying chamber to provide heat for the sublimation of solid water, thereby improving the dehydration and drying of the freeze-dried object.

[0071] Optionally, the cold trap 420 is equipped with a vacuum pump interface.

[0072] During vacuuming, air enters the vacuum pump through the cold trap 420. Solid water in the freeze-dried object sublimates into gaseous water, which flows with the air to the cold trap 420 and is then captured by the evaporator 140 within it. This arrangement prevents water molecules from entering the vacuum pump and causing damage. It should be noted that after the water molecules are captured by the evaporator 140 and condense into a solid state, since there is no heat source for sublimation, the solid water captured by the evaporator 140 will not sublimate again in the vacuum environment.

[0073] Optionally, the shell-and-tube heat exchanger 200 is located below the cold trap 420.

[0074] The shell-and-tube heat exchanger 200 is wound in a spiral shape, which allows for a longer length to be wound within a smaller space, thereby improving the heat exchange effect of the refrigerant within the shell-and-tube heat exchanger 200. The shell-and-tube heat exchanger 200 is positioned below the cold trap 420, which allows for a more compact layout of the cold trap 420 and the shell-and-tube heat exchanger 200, which is beneficial for the miniaturization of the freeze dryer.

[0075] Optionally, the compressor 110 is a fixed-frequency compressor 110, and the throttling device 130 is a capillary tube.

[0076] For a freeze dryer, the evaporator 140 maintains a low-temperature environment rather than creating one most of the time; therefore, the heat exchange of the evaporator 140 is relatively stable. The compressor 110 uses a fixed-frequency compressor, and the throttling device 130 employs a capillary tube, which can meet the refrigeration requirements of the freeze dryer and reduce its cost.

[0077] The foregoing description and accompanying drawings fully illustrate embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may include structural and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Parts and features of some embodiments may be included or substituted for parts and features of other embodiments. Embodiments of the present disclosure are not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from its scope. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A freeze dryer, It is characterized in that include: The refrigerant circulation loop is formed by connecting the compressor, condenser, throttling device and evaporator in sequence through refrigerant pipes; A shell and tube heat exchanger is constructed with a first refrigerant flow channel and a second refrigerant flow channel, the refrigerant flowing from the condenser to the throttling device flows through the first refrigerant flow channel, and the refrigerant flowing from the evaporator to the compressor flows through the second refrigerant flow channel; A bypass pipeline, a first end of which is connected to a first refrigerant pipe between the condenser and the throttling device, and a second end of which is connected to a second refrigerant pipe between the throttling device and the evaporator; A control valve, arranged in the bypass pipeline; Among them, during cooling, the temperature of the refrigerant entering the throttling device is lowered through the shell and tube heat exchanger, and the return air temperature of the compressor is increased through the shell and tube heat exchanger; during defrosting, the refrigerant flows through the condenser, the bypass pipeline, the evaporator and the second refrigerant flow channel of the shell and tube heat exchanger in sequence.

2. The freeze dryer according to claim 1, It is characterized in that The bypass pipeline is connected in parallel to the throttling device; or, The bypass pipeline is connected in parallel to the throttling device and the first refrigerant flow channel of the shell and tube heat exchanger.

3. The freeze dryer according to claim 1, It is characterized in that The shell and tube heat exchanger comprises an inner tube and an outer tube, the interlayer between the inner tube and the outer tube is a first refrigerant flow channel, and the interior of the inner tube is a second refrigerant flow channel.

4. The freeze dryer according to claim 1, It is characterized in that Also includes: A temperature sensor, used to obtain the return air temperature of the compressor; The control unit is configured to control the opening degree of the control valve according to the return air temperature of the compressor during defrosting.

5. The freeze dryer according to claim 4, It is characterized in that Also includes: A fan is provided corresponding to the condenser and is used for driving air to flow through the condenser to reduce the temperature of the condenser.

6. The freeze dryer according to claim 5, It is characterized in that The condenser is a microchannel condenser.

7. The freeze dryer according to claim 5, It is characterized in that The control unit is further configured to control the rotation speed of the fan according to the return air temperature of the compressor.

8. The freeze dryer according to any one of claims 1 to 7, It is characterized in that Also includes: The cold trap is constructed with a freezing space, the evaporator comprises a heat exchange tube, and the heat exchange tube is wound into a spiral shape in the freezing space to enclose a freezing area.

9. The freeze dryer according to claim 8, It is characterized in that Also includes: A drying chamber is located above the cold trap, a connecting window is provided at the bottom of the drying chamber, and the cold trap is connected to the connecting window through an opening at the top; A storage rack, which can be raised and lowered between the drying chamber and the cold trap; A heating device is arranged in the drying chamber.

10. The freeze dryer according to claim 8, It is characterized in that The shell and tube heat exchanger is arranged below the cold trap.

Images