A low temperature performance testing device for a multi-stage thermoelectric refrigerator working in a dewar

Abstract

The application discloses a kind of low-temperature performance testing devices of multistage thermoelectric refrigerator working in Dewar container, which carries out refrigeration performance test according to heat-generating element power, refrigerator operating current and other variables, analyzes the steady-state characteristics of refrigerator, analyzes the influence of transient change of key factors such as refrigerator operating current, cold and hot end temperature, cold and hot end temperature difference on refrigeration performance, finds the best performance parameter, obtains operation law, and factors affecting actual results, gives the transient characteristics of thermoelectric refrigerator working in Dewar space under variable-power heat-generating element, and provides reference ideas for thermoelectric refrigeration technology applied in infrared detector.

Description

Technical Field

[0001] This invention relates to the field of thermoelectric refrigeration technology, and more specifically to a low-temperature performance testing device for a multi-stage thermoelectric cooler operating in a Dewar container. Background Technology

[0002] Among various cooling technologies, semiconductor thermoelectric coolers have been widely used both domestically and internationally in recent years due to their small size, light weight, fast operating speed, high reliability, long lifespan, noiseless operation, and maintenance-free operation. Thermoelectric refrigeration is a solid-state refrigeration system with excellent shock resistance and precise dimensions, making it particularly suitable for replacing conventional refrigeration methods that cannot be used under extreme conditions. Therefore, thermoelectric coolers have already begun practical applications in the aerospace field and are developing rapidly, showing a trend of replacing mechanical refrigeration.

[0003] Among all cooling systems, thermoelectric cooling systems are unique in that they consist of only a single component. Thermoelectric cooling technology offers the following advantages: 1) It has no moving mechanical parts, resulting in a long lifespan and easy maintenance; 2) Its modular design ensures no significant performance loss when increasing cooling capacity; 3) It uses no working fluid, preventing leaks and environmental hazards; 4) Cooling temperature and rate are flexibly adjustable. Due to its advantages of long detection range, fast response rate, short start-up time, and low operating noise, thermoelectric cooling technology has a very broad application prospect in the field of cooled infrared detectors.

[0004] Currently, most mature cooled infrared detectors in China utilize Stirling cooling technology. However, this technology suffers from drawbacks such as high noise levels, loss of cooling capacity due to gas leakage within the gap, and short lifespan, thus limiting the development of cooled infrared detectors. Therefore, there is an urgent need to find a highly efficient, safe, environmentally friendly, space-saving, and flexibly adjustable cooler device. Summary of the Invention

[0005] To address the aforementioned problems, this invention designs a low-temperature performance testing device for a multi-stage thermoelectric cooler operating in a Dewar container. The device conducts cooling performance tests based on variables such as heating element power and cooler operating current, analyzes the steady-state characteristics of the cooler, and examines the impact of transient changes in key factors such as cooler operating current, hot and cold end temperatures, and hot and cold end temperature differences on cooling performance. It identifies optimal performance parameters, obtains operating rules, and identifies factors affecting actual results. The invention also presents the transient characteristics of a thermoelectric cooler operating with a variable-power heating element in a Dewar space, providing a reference for the application of thermoelectric cooling technology in infrared detectors.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A low-temperature performance testing device for a multi-stage thermoelectric cooler operating in a Dewar container, characterized in that it includes a thermoelectric cooling component, a Dewar encapsulation component, and a container parameter display module;

[0008] Thermoelectric refrigeration components include a four-stage semiconductor refrigeration module, a heating element, and a heat exchange platform;

[0009] Dewar encapsulation components, including the Dewar cavity, cooling fan, and exhaust tubing;

[0010] The enclosure parameter display module includes a DC adjustable constant voltage power supply and a temperature probe parameter display interface.

[0011] Furthermore, the four-stage semiconductor refrigeration module adopts a miniature four-stage semiconductor refrigeration chip, with the number of thermocouples from the first stage to the fourth stage being 89 pairs, 39 pairs, 17 pairs, and 8 pairs respectively. The cold end face size is 11mm x 11mm, and the hot end face size is 30mm x 22mm x 9mm.

[0012] Furthermore, the heating element is a ceramic heating element used to simulate the actual operating temperature of an infrared chip.

[0013] Furthermore, the heating element is disposed on the hot end of the miniature quadruple semiconductor refrigeration chip and bonded with silicone; the cold end of the miniature quadruple semiconductor refrigeration chip is disposed on the heat exchange platform and bonded with silicone, and six heat pipes with a diameter of 5mm are inserted in the heat exchange platform.

[0014] Furthermore, the Dewar cavity is located around the thermoelectric cooling component, and it is an aluminum alloy inner liner with an inner diameter of 63mm and an outer diameter of 69mm, and a quartz glass is provided on the top. A 2mm gap is provided between the aluminum alloy inner liner and the outer shell of the test device body, and heat insulation cotton is placed in the gap.

[0015] Furthermore, one end of the evacuation pipe is located outside the testing device, and the other end extends into the Dewar cavity. The evacuation pipe is used to evacuate the internal pressure of the Dewar cavity to -700 mmHg.

[0016] Furthermore, it also includes a heat sink for dissipating heat from the hot end of a miniature quadruple-stage thermoelectric cooler, the heat sink comprising two heat sinks arranged on the left and right, the heat pipes passing through the two heat sinks, and axial fans with a rotation speed of 12846 rpm mounted on the outside of the heat sinks respectively.

[0017] Furthermore, the heat sink has dimensions of 6mm x 6mm x 3.3mm, with each heat sink having a fin thickness of 1mm and a fin spacing of 2mm.

[0018] Furthermore, the temperature probe parameter display interface is located on the upper surface of the small box body and is used to display the values ​​of various parameters detected by the temperature probe.

[0019] Furthermore, five temperature probes are provided, and they are respectively located in the upper half of the Dewar cavity, on the cold end side of the fourth-stage cooling chip, on the hot end side of the fourth-stage cooling chip, in the lower half of the Dewar cavity, and on the heat sink side.

[0020] Temperature probe 1 is used to detect the temperature of the upper half of the Dewar cavity; temperature probe 2 is used to detect the cold end temperature of the fourth-stage thermocouple; temperature probe 3 is used to detect the hot end temperature of the fourth-stage thermocouple; temperature probe 4 is used to detect the temperature of the lower half of the Dewar cavity; temperature probe 5 is used to detect the heat sink temperature and can be used to detect the ambient temperature when the thermocouple is not activated.

[0021] Compared with the prior art, the beneficial effects of this invention are:

[0022] First, the testing device of the present invention uses a micro thermoelectric cooling module with a cold end face size of 11mm x 11mm and a hot end face size of 30mm x 22mm x 9mm, which significantly saves space compared to Stirling cooling.

[0023] Second, the testing device of the present invention has a cooling temperature difference of 100K and a minimum cold end temperature of -74℃, which can meet the requirements of most infrared detectors.

[0024] Third, the testing device of the present invention has a short cooling time and can achieve stable operation after 130 seconds of startup.

[0025] In summary, this invention proposes a low-temperature performance testing device for multi-stage thermoelectric coolers operating in a Dewar container. Using this device, low-temperature performance tests can be conducted, and data on the hot and cold junction temperatures and the cooling temperature difference can be collected, enabling cooler performance analysis. This solves the problem of analyzing the steady-state and transient characteristics of miniature multi-stage thermoelectric coolers within a Dewar space, with and without heating elements, providing an experimental platform and reference approach for verifying the practical application of thermoelectric cooling technology in the field of cooled infrared detectors. Attached Figure Description

[0026] Figure 1 This is a model diagram of the test device of the present invention.

[0027] Figure 2 This is a physical image of the testing device of the present invention.

[0028] Figure 3 This is a diagram showing the dimensional parameters of a four-stage refrigeration element.

[0029] Figure 4 This is a schematic diagram of a thermoelectric refrigeration structure.

[0030] Figure 5 This is a model diagram of the Dewar encapsulation structure.

[0031] Figure 6 A picture of the actual Dewar package.

[0032] Figure 7 This is a physical diagram of the radiator structure.

[0033] Figure 8 This is a physical diagram of the radiator structure.

[0034] Figure 9 This is a diagram of the parameter display interface for the box-type module.

[0035] Figure 10 This is a diagram showing the internal layout of the box-type module.

[0036] Figure 11 This is a picture of the actual equipment used for testing the refrigeration unit.

[0037] Figure 12 (a)-(d) are the temperature trends of the cold end of heating elements with different power.

[0038] Figure 13 (a)-(d) are the temperature trends of the hot end of heating elements with different power.

[0039] Figure 14 (a)-(d) are trend graphs of temperature difference between the hot and cold ends of heating elements with different power.

[0040] Figure 15 (a)-(c) are comparison charts showing the cold and hot ends, and temperature difference, of the components without heating elements and the 200MW heating element at different ambient temperatures when the voltage is set to 12.6V. Detailed Implementation

[0041] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0042] The analysis and optimization of thermoelectric coolers are generally carried out under steady-state conditions, but the lowest achievable cooling temperature and the time required to reach the operating temperature are also important parameters that must be considered. Based on this, this invention proposes a low-temperature performance testing device for multi-stage thermoelectric coolers operating in a Dewar container.

[0043] 1. Model design of the testing device

[0044] Figures 1-2The images show a model diagram and a physical diagram of the refrigeration testing device. As can be seen from the diagrams, the testing device consists of a thermoelectric refrigeration assembly, a Dewar encapsulation assembly, and a box-mounted parameter display module. The thermoelectric refrigeration assembly mainly includes a four-stage semiconductor refrigeration module and a heating element; the Dewar encapsulation assembly mainly includes a Dewar cavity, heat pipes, a cooling fan, and an extraction pipeline; the box-mounted parameter display module mainly includes a DC adjustable constant voltage power supply and a temperature probe parameter display interface.

[0045] 2. Description of the internal structure of the testing device

[0046] (1) Thermoelectric refrigeration components

[0047] Considering the size constraints of cooled infrared detectors, this testing device uses a miniature four-stage semiconductor thermocouple, with the number of thermocouples from the first stage to the fourth stage being 89 pairs, 39 pairs, 17 pairs, and 8 pairs respectively; the cold end dimensions are 11mm x 11mm, and the hot end dimensions are 30mm x 22mm x 9mm. Figure 3 The diagram shows the dimensions of the four-stage thermal cooler. As can be seen from the diagram, its performance parameters are: maximum current 8.0A, maximum voltage 12.6V. Considering the analysis of the operating performance of chips with different power ratings, this test setup uses a ceramic heating element (i.e., heating element) to simulate the actual operating temperature of the infrared chip.

[0048] Figure 4 The diagram shows a thermoelectric cooling structure, primarily consisting of a four-stage semiconductor cooling chip, a heating element, and a heat exchange platform. The heating element is placed at the hot end of the four-stage cooling chip and bonded to it with thermally conductive silicone. The cold end of the four-stage cooling chip is placed on a pure copper heat exchange platform and bonded to it with silicone. Six 5mm diameter heat pipes are inserted through the heat exchange platform. This structure allows for efficient cooling of the heating element and the Dewar space via the four-stage cooling chip, while heat from the hot end is transferred to the heat exchange platform and effectively dissipated through the heat pipes.

[0049] (2) Dewar encapsulation structure

[0050] To fully investigate the cooling characteristics of the thermoelectric cooler within the Dewar space, this invention incorporates a Dewar cavity into the cooler testing device. The overall structure measures 79mm in diameter and 68.7mm in height. Considering the need for both excellent thermal insulation and light transmission through the Dewar cavity to the infrared chip during actual operation of the cooled infrared detector, an aluminum alloy inner liner with an inner diameter of 63mm and an outer diameter of 69mm is installed around the thermoelectric cooling structure, with quartz glass at the top to create conditions for the optical chip's operation and fully simulate the actual working environment. To achieve optimal thermal insulation, a nylon outer shell with an inner diameter of 75mm and an outer diameter of 79mm is 3D printed based on the metal inner liner, with a 2mm gap between the inner liner and the outer shell for insulation cotton.

[0051] To achieve and verify the vacuum environment of the Dewar cavity in the testing device, a vacuum pipe is designed at the bottom of the device. One end of this pipe is located outside the device, and the other end extends into the Dewar encapsulation structure. The vacuum equipment can evacuate the cavity to -700 mmHg and maintain a pressure rise of no more than 1.4% within three days. The vacuum level can be checked before each experiment through the vacuum pipe port to ensure the accuracy of the experimental data. Figures 5-6 The images shown are a model diagram of the Dewar package structure and an actual Dewar package. This structure allows the thermoelectric cooling module and chip to be kept in a vacuum environment for extended periods, effectively isolating radiative heat transfer and fully simulating real-world working scenarios, thus making the experimental data more realistic and effective.

[0052] (3) Heat sink structure

[0053] To ensure adequate heat dissipation from the hot end of the cooling module, the test device employs a dual cooling method of air cooling and heat pipe cooling. Figure 7 The image shows the actual structure of the heatsink. It can be seen that six 5mm diameter heat pipes are inserted into two heat sinks, one on the left and one on the right. The heat sinks measure 6mm x 6mm x 3.3mm, with 1mm thick fins on each heat sink and a 2mm fin spacing. Axial fans with a rotation speed of 12846rpm are installed on both sides to provide forced air cooling to the two heat sinks.

[0054] (4) Box body parameter display structure

[0055] In order to collect experimental data more comprehensively, such as Figure 8 As shown, five temperature probes are installed at different locations in the testing device: the upper half of the Dewar cavity, the cold end side of the fourth-stage thermocouple, the hot end side of the fourth-stage thermocouple, the lower half of the Dewar cavity, and the heat sink side. The heating element and the fourth-stage thermocouple are equipped with adjustable voltage and current. Temperature probe 1 is used to detect the temperature of the upper half of the Dewar cavity. Temperature probe 2 is used to detect the cold end temperature of the fourth-stage thermocouple. Temperature probe 3 is used to detect the hot end temperature of the fourth-stage thermocouple. Temperature probe 4 is used to detect the temperature of the lower half of the Dewar cavity. Temperature probe 5 is used to detect the heat sink temperature and can be used to detect the ambient temperature when the thermocouple is not activated.

[0056] To make data observation more convenient and intuitive, a parameter detection and power supply module was designed, integrating various parameters and power supply into a small box. Figures 9-10 The diagrams show the parameter display interface of the box module and its internal layout. For ease of use and accuracy, the four-stage cooler can be powered by either the box module itself or an external power source via a cooler switch. This design allows all experimental parameters to be centrally displayed on the box module, facilitating observation and clearly showing trends in parameter changes.

[0057] 3. Functions of the Refrigerator Testing Device

[0058] Figure 11 The figure shows a physical diagram of the refrigerator testing device. By setting two independent variables—different power levels for the heating element and different current levels for the four-stage cooling coils—key parameters such as the cold end temperature of the cooling coils, the hot end temperature of the cooling coils, the top temperature of the Dewar space, the bottom temperature of the Dewar space, the heat sink temperature, and the ambient temperature can be observed on the parameter display interface of the enclosure. This facilitates steady-state and transient analysis of the refrigerator based on the experimental parameters, allowing for the determination of the refrigerator's performance trends as a function of the variables, while simultaneously verifying the effectiveness of the computational model.

[0059] 4. Performance of the Refrigerator Testing Device

[0060] (1) At an ambient temperature of 11℃, heating elements with power of 0W, 200MW, and 2W are added. The maximum currents corresponding to the maximum voltage of 12.6V are 7.92A, 7.92A, and 7.93A, respectively. The minimum cold end temperatures are -74℃, -73℃, and -66℃, respectively. The maximum hot end temperatures are 25℃, 26℃, and 25℃, respectively. The maximum temperature difference is 99K, 99K, and 91K, respectively.

[0061] (2) At an ambient temperature of 23°C, when heating elements with power of 0W and 200MW are added, the maximum currents corresponding to the maximum voltage of 12.6V are 7.56A and 7.57A, respectively. The minimum cold end temperatures are -68°C and -67°C, respectively, the maximum hot end temperatures are 32°C and 32°C, respectively, and the maximum temperature difference is 100K and 99K, respectively.

[0062] (3) Under the combined conditions of different ambient temperatures and different power of heating elements, it can achieve stable operation after 130 seconds.

[0063] Example

[0064] To further verify the testing effect of the testing device of the present invention, an experiment was conducted to investigate the effect of the heating element on the cooling performance of the refrigerator. When the ambient temperature was 11°C, the power of the heating element was set to 0W, 200MW, and 2W at different voltages, and the parameters of the refrigerator testing device were observed after working for 3 minutes.

[0065] 1. The impact of heating elements on the cold end of the refrigerator

[0066] Figure 12Figures (a)-(d) show the cold junction temperature trends of refrigerators containing heating elements of different power levels when operating at voltages of 3V, 6V, 9V, and 12.6V. The figures show that the cold junction temperatures change significantly within 10 seconds of power-on when 0W, 200MW, and 2W heating elements are added, and stabilize after 130 seconds. However, the higher the voltage, the smaller the final difference in cold junction temperature becomes over time.

[0067] 2. The impact of heating elements on the hot end of the refrigerator

[0068] Figure 13 Figures (a)-(d) show the temperature trends of the hot end of refrigerators containing heating elements of different power when operating at voltages of 3V, 6V, 9V, and 12.6V. As can be seen from the figures, the temperature trends of the hot end over time are roughly the same after adding 0W, 200MW, and 2W heating elements.

[0069] 3. The effect of heating elements on the temperature difference of the refrigerator

[0070] Figure 14 Figures (a)-(d) show the temperature difference trends at the hot and cold ends of refrigerators containing heating elements of different power when operating at voltages of 3V, 6V, 9V, and 12.6V. The figures show that with 0W, 200MW, and 2W heating elements, the temperature difference changes significantly within 10 seconds of startup and stabilizes after 130 seconds. However, the higher the voltage, the smaller the final temperature difference at the cold end becomes over time. In conclusion, a higher heating element power results in lower cooling performance in the initial stage of operation, but does not affect the time to achieve stable operation.

[0071] Figure 15 Figures (a)-(c) show the time-cold junction temperature trend, time-hot junction temperature trend, and time-temperature difference trend for the cooler without a heating element and with a 200MW heating element at different ambient temperatures, respectively, when the voltage is set to 12.6V. As can be seen from the figures, compared with the transient analysis of the cooler without a heating element at different ambient temperatures, the cooler with the 200MW heating element shows no significant change in the cold junction temperature, hot junction temperature, and temperature difference. Furthermore, given that the power of cooled infrared detector chips is generally 175MW, it can be concluded that the cooling performance of the test device of this invention basically meets the chip requirements.

[0072] The foregoing has shown and described the basic principles, main attributes, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A low-temperature performance testing device for a multi-stage thermoelectric cooler operating in a Dewar container, characterized in that, Includes thermoelectric cooling components, Dewar encapsulation components, and a package parameter display module; Thermoelectric refrigeration components include a four-stage semiconductor refrigeration module, a heating element, and a heat exchange platform; Dewar encapsulation components, including the Dewar cavity, cooling fan, and exhaust tubing; The box-type parameter display module includes a DC adjustable constant voltage power supply and a temperature probe parameter display interface; The heating element is disposed on the hot end of the miniature quadruple semiconductor refrigeration chip and is bonded with silicone; the cold end of the miniature quadruple semiconductor refrigeration chip is disposed on the heat exchange platform and is bonded with silicone, and six heat pipes with a diameter of 5mm are inserted in the heat exchange platform. The Dewar cavity is located around the thermoelectric cooling component and is an aluminum alloy liner with an inner diameter of 63mm and an outer diameter of 69mm. Quartz glass is installed on the top. A 2mm gap is provided between the aluminum alloy liner and the outer shell of the test device body, and heat insulation cotton is placed in the gap. It also includes a heat sink for dissipating heat from the hot end of a miniature quadruple-level semiconductor cooling chip, the heat sink comprising two heat sinks arranged on the left and right, the heat pipes passing through the two heat sinks, and axial fans with a rotation speed of 12846 rpm mounted on the outside of the heat sinks respectively. The temperature probe parameter display interface is located on the upper surface of the small box and is used to display the values ​​of various parameters detected by the temperature probe. Five temperature probes are provided, and they are respectively located in the upper half of the Dewar cavity, on the cold end side of the fourth-stage cooling chip, on the hot end side of the fourth-stage cooling chip, in the lower half of the Dewar cavity, and on the heat sink side. Temperature probe 1 is used to detect the temperature of the upper half of the Dewar cavity; temperature probe 2 is used to detect the cold end temperature of the fourth-stage thermocouple; temperature probe 3 is used to detect the hot end temperature of the fourth-stage thermocouple; temperature probe 4 is used to detect the temperature of the lower half of the Dewar cavity; temperature probe 5 is used to detect the heat sink temperature and can be used to detect the ambient temperature when the thermocouple is not activated.

2. The low-temperature performance testing device for a multi-stage thermoelectric cooler operating in a Dewar container as described in claim 1, characterized in that, The four-stage semiconductor refrigeration module uses a miniature four-stage semiconductor refrigeration chip. The number of thermocouples from the first stage to the fourth stage is 89 pairs, 39 pairs, 17 pairs, and 8 pairs, respectively. The cold end face size is 11 mm x 11 mm, and the hot end face size is 30 mm x 22 mm x 9 mm.

3. The low-temperature performance testing device for a multi-stage thermoelectric cooler operating in a Dewar container as described in claim 1, characterized in that, The heating element uses a ceramic heating element to simulate the actual operating temperature of an infrared chip.

4. The low-temperature performance testing device for a multi-stage thermoelectric cooler operating in a Dewar container as described in claim 1, characterized in that, One end of the evacuation pipe is located outside the test device, and the other end extends into the Dewar cavity. The pressure inside the Dewar cavity is evacuated to -700 mmHg through the evacuation pipe.

5. The low-temperature performance testing device for a multi-stage thermoelectric cooler operating in a Dewar container as described in claim 1, characterized in that, The heat sink measures 6mm x 6mm x 3.3mm, with each heat sink having a fin thickness of 1mm and a fin spacing of 2mm.

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