Ini adalah hal yang terlihat sangat tidak mencolok. Ini hanya seukuran telapak tangan, dan sedikit berat di tangan. Bentuknya cukup istimewa. Sebuah tabung logam tipis seperti tiang, membawa dua silinder logam tebal, dan salah satu silinder logam diikuti oleh setengah dari tabung sedikit lebih tipis dari jari kelingking.
Salah satu lemari es tabung nadi-kelas dirgantara
Zhao Miguang, seorang peneliti di Institut Fisika dan Kimia Akademi Ilmu Pengetahuan China (selanjutnya disebut Institut Fisika dan Kimia Akademi Ilmu Pengetahuan China), mengatakan bahwa dibutuhkan sekitar satu juta yuan untuk membuat benda ini. sekarang. Namun, sebelum tahun 2000, negara asing tidak akan menjualnya ke China, berapa pun 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.
Dinginkan hingga minus 200 derajat Celcius dalam beberapa menit
Pada tanggal 25 Januari, satelit ZY-1 02E yang dilengkapi dengan tiga lemari es tabung pulsa-buatan dalam negeri berhasil memperoleh gambar berkualitas tinggi-. Ketiga lemari es tabung pulsa ini adalah lemari es tabung pulsa kelas kedirgantaraan ke-26, ke-27, dan ke-28 yang dikembangkan oleh Institut Fisika dan Kimia dari Akademi Ilmu Pengetahuan China dan berhasil digunakan dalam proyek luar angkasa.
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.
Lantas, bagaimana cara menjaga agar detektor infra merah pada satelit tetap dalam keadaan suhu rendah? Para ilmuwan telah menemukan dua jenis teknologi pendinginan, satu adalah pendinginan radiasi pasif, yang didasarkan pada prinsip bahwa benda bersuhu tinggi-dapat memancarkan energi ke benda bersuhu rendah-; yang lainnya adalah pendinginan mekanis aktif, prinsipnya adalah membuat gas melalui gerakan mekanis. ekspansi, dan fenomena pendinginan terjadi ketika 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 pendinginan tabung pulsa adalah sejenis teknologi pendinginan mekanis. Pada tahun 1963, ilmuwan Amerika secara tidak sengaja menemukan bahwa ketika ada gelombang tekanan bolak-balik dalam tabung hampa, ujungnya yang tertutup akan memanas, dan gradien suhu yang besar dapat terbentuk di sepanjang arah aksial tabung. Berdasarkan ini, mereka mengembangkan pendinginan tabung pulsa. mesin. Pada tahun 1984, ilmuwan Soviet mengubah lemari es tabung pulsa, yang sangat meningkatkan efisiensi pendinginannya, dan panas penelitian terkait 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 ke rekayasa
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 dukungan Dana Sains Nasional untuk Cendekiawan Muda Terhormat, Akademi Ilmu Pengetahuan Tiongkok dan departemen terkait lainnya, tim peneliti Institut Fisika dan Kimia Akademi Ilmu Pengetahuan Tiongkok mulai berubah menjadi penelitian terapan. secara keseluruhan. Menghadapi kebutuhan utama di bidang penginderaan jauh antariksa nasional dan deteksi inframerah, mereka keluar dari tumpukan kertas-kertas lama dan melakukan penelitian tentang rekayasa lemari es tabung pulsa dan aplikasi ruang angkasa. Mulai tahun 2000, tim menerima dukungan sistematis dari Badan Antariksa Nasional.
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.
Lemari es diisi dengan gas helium, dan harus memastikan tingkat kebocoran molekul helium yang sangat rendah melalui teknologi pengelasan dan penyegelan yang andal. Kompresi dan ekspansi gas tergantung pada piston. Mereka harus membuat piston dan dinding silinder rapat dan tidak-bersentuhan, untuk memastikan piston tidak aus saat oli tidak dapat digunakan. Pergerakan piston ditopang oleh pegas datar, dan mereka harus mencari cara untuk memastikan pegas tidak bengkok, apalagi patah.
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 lemari es tabung pulsa telah diservis
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 berhasil diluncurkan. Itu dilengkapi dengan kulkas tabung pulsa dengan kapasitas pendinginan yang besar dan umur panjang yang dikembangkan oleh Institut Fisika dan Kimia dari Akademi Ilmu Pengetahuan 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 desain menjadi kenyataan sangat bergelombang. Namun, semakin banyak kegagalan yang Anda alami, semakin tak terlupakan kebahagiaan kesuksesan.
"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.
Saat ini, mereka telah mengembangkan lemari es tabung pulsa kelas-kedirgantaraan dengan berbagai bentuk dan kinerja, 28 di antaranya telah diluncurkan ke orbit.
Setiap proyek penuh dengan tantangan, dan tantangan ini adalah kekuatan pendorong di belakang tim pengembangan lemari es tabung pulsa.
"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.
