Ini adalah perkara yang kelihatan sangat tidak mencolok. Ia hanya sebesar tapak tangan, dan ia sedikit berat di tangan. Bentuknya agak istimewa. Tiub logam nipis adalah seperti tiang, membawa dua silinder logam tebal, dan satu daripada silinder logam diikuti oleh separuh tiub yang nipis sedikit daripada jari kelingking.
Salah satu peti sejuk tiub nadi gred-aeroangkasa
Zhao Miguang, seorang penyelidik di Institut Fizik dan Kimia Akademi Sains China (selepas ini dirujuk sebagai Institut Fizik dan Kimia Akademi Sains China), berkata bahawa ia akan menelan belanja kira-kira satu juta yuan untuk membuat benda ini. sekarang. Walau bagaimanapun, sebelum tahun 2000, negara asing tidak akan menjualnya kepada China, tidak kira berapa harganya.
It is the "cooling artifact" that has plagued China's optical remote sensing satellites for decades - the aerospace-grade pulse tube refrigerator, a high-tech product that can quickly reduce the local temperature to minus 200 degrees Celsius and will not be damaged for many years.
Its birth and development in China benefited from a "long run" by researchers from the Chinese Academy of Sciences.
Sejukkan hingga minus 200 darjah Celsius dalam beberapa minit
Pada 25 Januari, satelit ZY-1 02E yang dilengkapi dengan tiga peti sejuk tiub nadi-buat domestik berjaya memperoleh-imej berkualiti tinggi. Tiga peti sejuk tiub nadi ini adalah peti sejuk tiub nadi gred aeroangkasa ke-26, 27 dan ke-28 yang dibangunkan oleh Institut Fizik dan Kimia Akademi Sains China dan berjaya digunakan dalam projek angkasa lepas.
The new crown epidemic has made many people aware of "infrared temperature measurement" technology. When the human body passes through the thermal imaging camera, the hot spots on the body will appear red. In order to measure the temperature of the earth and the atmosphere, many meteorological satellites are also equipped with infrared detectors. However, due to the distance from the target detection object, the infrared detector on the satellite needs to maintain a low temperature or even an extremely low temperature level in order to detect the slightest heat change on the distant target.
Jadi, bagaimana untuk mengekalkan pengesan inframerah pada satelit dalam keadaan suhu rendah? Para saintis telah mencipta dua jenis teknologi penyejukan, satu ialah penyejukan sinaran pasif, yang berdasarkan prinsip bahawa objek-suhu tinggi boleh memancarkan tenaga kepada objek-bersuhu rendah; yang lain adalah penyejukan mekanikal aktif, prinsipnya adalah untuk membuat gas melalui pergerakan mekanikal. pengembangan, dan fenomena penyejukan berlaku apabila gas mengembang.
"The cooling temperature of radiation cooling is high and the cooling capacity is small. Although it can be used to cool small detectors, it cannot meet the higher requirements for low temperature of aerospace devices. In contrast, mechanical cooling technology is more feasible." Chinese Academy of Sciences Physics and Chemistry Chen Houlei, a researcher at the institute, told the China Science Journal.
Teknologi penyejukan tiub nadi adalah sejenis teknologi penyejukan mekanikal. Pada tahun 1963, saintis Amerika secara tidak sengaja mendapati bahawa apabila terdapat gelombang tekanan berselang-seli dalam tiub berongga, hujung tertutupnya akan menjadi panas, dan kecerunan suhu yang besar boleh terbentuk di sepanjang arah paksi tiub. Berdasarkan ini, mereka membangunkan penyejukan tiub nadi. mesin. Pada tahun 1984, saintis Soviet mengubah peti sejuk tiub nadi, yang sangat meningkatkan kecekapan penyejukannya, dan haba penyelidikan yang berkaitan juga meningkat.
Pointing to the pulse tube refrigerator in his hand, Chen Houlei introduced: "This part similar to the little finger is called the 'cold finger'. This small refrigerator can reduce the fingertip to minus 200 in a few minutes. Celsius. We put the probe on the fingertip, and when the temperature of the probe cools down, we can see the earth clearly."
Dari teori kepada kejuruteraan
In the 1980s, the Cryogenic Technology Experiment Center of the Chinese Academy of Sciences (one of the units of the Institute of Physics and Chemistry of the Chinese Academy of Sciences) took the lead in starting the basic research on pulse tube refrigeration technology in China. By the 1990s, they had set the record for the lowest refrigeration temperature several times, achieved a series of original achievements, and won the "Kapicha Award" and "Linde Award" of the International Society of Refrigeration.
In 1998, the United States was the first to engineer pulse-tube refrigerators for use in space programs. Although my country has achieved world-leading results in the basic research of pulse tube refrigeration, optical remote sensing satellites have been suffering from lack of their own space refrigerators. "At that time, the research and development unit could only import from abroad, and the aerospace-grade refrigerator was embargoed to our country. The research and development unit could only try every way to buy the ground-level refrigerator." Zhao Miguang said.
The reason for saying "bitter" is that the lifespan of imported ground-level refrigerators is less than 1/10 of that of aerospace-grade refrigerators, and problems often occur, and after satellites are launched, they cannot be repaired at any time like they are on the ground. Once on-orbit failure, the country may pay a huge price.
Pada akhir 1990-an, dengan sokongan Dana Sains Kebangsaan untuk Ulama Muda Terbilang, Akademi Sains China dan jabatan lain yang berkaitan, pasukan penyelidik Institut Fizik dan Kimia Akademi Sains China mula berubah menjadi penyelidikan gunaan secara keseluruhan. Menghadapi keperluan utama dalam bidang penderiaan jauh angkasa lepas dan pengesanan inframerah, mereka melangkah keluar dari timbunan kertas lama dan menjalankan penyelidikan mengenai kejuruteraan peti sejuk tiub nadi dan aplikasi ruang. Bermula pada tahun 2000, pasukan itu menerima sokongan sistematik daripada Agensi Angkasa Negara.
The road from theory to engineering is full of challenges. "What we want to do is aerospace-grade products. If the refrigerator will work in the sky in the future, it must be guaranteed that it will not break for 8 years, 10 years or even longer." Chen Houlei said.
Peti sejuk diisi dengan gas helium, dan ia mesti memastikan kadar kebocoran molekul helium yang sangat rendah melalui teknologi kimpalan dan pengedap yang boleh dipercayai. Mampatan dan pengembangan gas bergantung pada omboh. Mereka mesti menjadikan omboh dan dinding silinder rapat dan tidak-bersentuh, untuk memastikan omboh tidak haus apabila minyak tidak boleh digunakan. Pergerakan omboh disokong oleh spring rata, dan mereka mesti mencari jalan untuk memastikan spring tidak bengkok, apatah lagi pecah.
Every "must" means a pressure. "At that time, we encountered some problems, and we couldn't move forward for a long time, and everyone's morale was very low." Zhao Miguang said.
Summarize the progress at 8:00 in the morning, and leave work at 12:00 in the evening. In this way, 8 years have passed. In the past 8 years, Riyuexingchen has witnessed their road to tackling key problems: the pulse tube refrigerator they developed achieved full welding of titanium alloys; the distance between the piston and the cylinder reached the micron level; the leaf spring can move 100 in the anti-fatigue test. More than 100 million times, there is even a spring's anti-fatigue test "running" for more than 10 years, and there is no problem so far.
28 peti sejuk tiub nadi telah dimasukkan ke dalam perkhidmatan
In 2008, under the leadership of researcher Liang Jingtao, the current director of the Key Laboratory of Space Work-Heat Conversion Technology, Institute of Physics and Chemistry, Chinese Academy of Sciences, the scientific research team developed my country's first long-life pulse tube refrigerator in space, and successfully carried out on-orbit verification. The refrigerator has achieved a historic leap from scratch, from tracking to entering the latest international development stage, and my country has thus become the second country after the United States to master the space pulse tube refrigeration technology.
Since then, the "stumbling block" in the development of optical satellites in the infrared spectrum has been kicked away, and the planning and demonstration of a series of satellite models in the country has been in full swing.
Technological innovation creates demand, which in turn drives technological development. In the following ten years, the development of my country's spaceborne infrared detectors has continuously put forward higher requirements for spaceborne pulse tube refrigerators.
Pada 9 Mei 2018, satelit Gaofen-5 telah berjaya dilancarkan. Ia dilengkapi dengan peti sejuk tiub nadi dengan kapasiti penyejukan yang besar dan jangka hayat yang panjang yang dibangunkan oleh Institut Fizik dan Kimia Akademi Sains China.
This satellite carries my country's first full-spectrum spectral imager covering the visible, near-infrared, short-wave, medium-wave, and long-wave infrared spectrum bands. Compared with previous optical detectors, it is larger and heavier. In order to adapt to the demand, the chiller project team boldly adopted a new solution. The chiller could only carry the cold finger of the cold platform with a size of more than ten millimeters and a weight of a few grams, and designed it into a detector assembly with a size of one hundred millimeters and a weight of one kilogram. .
Dalam beberapa tahun pertama, jalan untuk mengubah reka bentuk menjadi realiti adalah bergelombang. Walau bagaimanapun, semakin banyak kegagalan yang anda alami, semakin tidak dapat dilupakan kegembiraan kejayaan.
"This is a new international initiative!" Chen Houlei's eyes lit up when he said this.
At 11:11 on December 26, 2021, the "Ziyuan No. 1 02E" satellite was successfully launched at the Taiyuan Satellite Launch Center. The long-wave infrared detector carried on it must work in a low temperature environment of minus 193 degrees Celsius. The spectral imager on Gaofen-5 is larger and requires twice the cooling area of the pulse-tube refrigerator.
During the development process, researchers encountered unprecedented difficulties. "The design life of the 'Zuanyu No. 1 02E' satellite is 10 years, which is higher than the previous 8-year life requirement. In order to meet the project requirements, we proposed a plan to use the switching device to backup the compressor. In the case of increasing the limited weight, the large It greatly improves the life of the refrigerator." Liu Yanjie, the chief designer of this pulse tube refrigerator and an associate researcher at the Institute of Physics and Chemistry of the Chinese Academy of Sciences, told the China Science Journal.
"During the design of the cold finger, the large-area cold plate we used had a deformation problem due to thermal expansion and contraction, and the detector on it was easily broken." The cold finger designer of this pulse tube refrigerator, Quan Jia, an associate researcher at the Institute of Physics and Chemistry of the Chinese Academy of Sciences, recalled that after countless discussions and debugging, they made a new material match for the cold plate and finally solved the problem.
Hari ini, mereka telah membangunkan peti sejuk tiub nadi gred-aeroangkasa dengan pelbagai bentuk dan prestasi, yang mana 28 daripadanya telah dilancarkan ke orbit.
Setiap projek penuh dengan cabaran, dan cabaran ini adalah penggerak di sebalik pasukan pembangunan peti sejuk tiub nadi.
"We are developing more advanced space low-temperature refrigeration technology with a cooling capacity of more than 100 watts, a temperature close to absolute zero, and a weight as low as a few hundred grams." Liang Jingtao said that the team will build on the successful development of the space pulse tube refrigerator. Continue to carry forward the spirit of "daring to challenge and fight hard", bravely assume "national responsibility", and forge ahead to meet the needs of low-temperature refrigeration in future spaces.
On the development road of aerospace-grade cryogenic refrigerator technology, this "long run" continues.
