In today's technological world, mobile phones serve as communication tools that we rely on closely in daily life, spacecraft carry humanity's grand dream of exploring the universe, and the Qinghai-Tibet Railway stands as a magnificent project that crosses harsh geographical environments. Though they seem to have no connection, they share a crucial common need: maintaining an appropriate temperature. It is important to note that if heat cannot be dissipated effectively, the consequences could be unimaginable. Mobile phones may deform due to overheating, impairing their performance; spacecraft may malfunction due to loss of temperature control, endangering mission execution; and the subgrade of the Qinghai-Tibet Railway may distort due to temperature changes, threatening traffic safety. Among the numerous solutions to address this series of critical temperature issues, one high-performance heat transfer component stands out—it is the heat pipe. 01 The Invention and Development of Heat Pipes Looking back to 1963, heat pipe technology was successfully invented by George Grover of the Los Alamos National Laboratory in the United States. Just one year later, in 1964, the world's first paper on heat pipes was officially published. Like a bombshell, it caused a sensation in the field of heat transfer. The renowned heat transfer scientist and member of the U.S. National Academy of Engineering, Tien Chang-lin, even argued that the impact of this mere two-page paper was as enormous and far-reaching as that of atomic energy. China has also kept pace in heat pipe research, demonstrating determination and strength in catching up. As early as 1968, the Chinese Academy of Sciences, relying on the wisdom and efforts of its researchers, successfully developed the first heat pipe prototype, laying a solid foundation for the development of China's heat pipe industry. However, the development of heat pipes has not been a smooth journey. Its earliest research can be traced back to 1942, when Gauglar, an engineer at the U.S. General Motors Corporation, proposed a new concept of enhanced heat transfer components and boldly applied for a patent. Regrettably, at that time, countries around the world were deeply immersed in the chaos of World War II and had no time to pay attention to this innovative idea. As a result, this patent lay dormant in the dust of history for nearly 20 years. It was not until 1964 that the heat pipe was first manufactured at the Los Alamos National Laboratory and officially named as such. After that, the most direct and critical reason for the rapid rise of heat pipe technology lay in the fierce space race between the United States and the Soviet Union at that time. In that era, without heat pipes to effectively solve the temperature control problem of spacecraft, the development of spacecraft would have fallen into great trouble, or even come to a standstill. "The 'Invisible Heroes' in the Tech World! How Does Heat Pipe Technology Change Our Lives?" 02 The Working Principle of Heat Pipes A heat pipe, as a heat transfer component that cleverly utilizes the principles of heat conduction and phase change, has an intricate scientific mechanism behind its operation. A typical heat pipe is usually carefully composed of a tube shell, a wick, and end caps. When one end of the heat pipe receives heat input, the working fluid inside the tube responds quickly to this change. Heated, the working fluid evaporates rapidly, transforming from a liquid to a gaseous state. The gas generated by this evaporation process flows toward the other end of the heat pipe driven by an extremely small pressure difference. When the gas reaches the other end, where the temperature is relatively lower, it releases the heat it carries and condenses back into a liquid. The condensed liquid then flows back to the original evaporation end through various means such as capillary action. This cycle repeats endlessly, enabling the fast and efficient transfer of heat from one end to the other. Specifically, the heat transfer process of a heat pipe consists of six closely linked steps. First, heat is transferred from the heat source through the heat pipe's wall and the wick filled with working fluid to the liquid-vapor interface. Next, the liquid undergoes intense evaporation at the liquid-vapor interface in the evaporation section. Subsequently, the vapor in the vapor cavity generated by evaporation flows smoothly from the evaporation section to the condensation section. Inside the condensation section, the vapor condenses rapidly at the vapor-liquid interface. Immediately after, heat is accurately transferred from the vapor-liquid interface to the cold source through the wick, liquid, and tube wall. Finally, within the wick, the condensed working fluid flows back to the evaporation section smoothly due to the remarkable force of capillary action, preparing for the next cycle of heat transfer. 03 The Technical Characteristics of Heat Pipes Heat pipes possess a series of remarkable technical characteristics. First, they exhibit an amazing high-speed heat conduction effect, with thermal conductivity far exceeding that of any known metal. Second, heat pipes are lightweight in structure, relatively simple in design, and easy to manufacture and maintain. Third, they can achieve uniform temperature distribution and perform temperature equalization or isothermal operations, ensuring the stability and reliability of the heat transfer process. Moreover, heat pipes have a large heat transfer capacity and a long heat transfer distance, enabling effective heat transfer over a relatively large spatial range. More importantly, they have no active components during operation and do not consume electricity themselves, greatly reducing energy consumption. At the same time, heat pipes have no restrictions on heat transfer direction—the evaporation end and condensation end can be flexibly swapped according to actual needs. Furthermore, heat pipes are easy to process and can change the heat transfer direction based on specific application scenarios, offering high flexibility and adaptability. Finally, they are durable, have a long service life, high reliability, and are easy to store and preserve, providing strong support for their long-term stable operation in various complex environments. 04 The Materials and Common Working Fluids of Heat Pipes The two ends of a heat pipe have distinct functional divisions: one end is the evaporation section, and the other is the condensation section. The selection of the working fluid used inside the heat pipe is an extremely critical issue, which must be carefully chosen based on the operating temperature range. This is because the working principle of a heat pipe relies on the phase change of the internal fluid; therefore, both gas and liquid phases must coexist within its operating temperature range. If the ambient temperature is lower than the operating temperature, the liquid will be unable to evaporate into gas, causing the heat pipe to fail to work normally. Conversely, if the ambient temperature is higher than the operating temperature, the heat pipe will be filled with gas, making condensation impossible. In both extreme cases, the heat pipe can only conduct heat through its tube wall, with an effect similar to that of ordinary metal heat conduction. For this reason, liquid helium is used as the working fluid in extremely low-temperature environments (2-4K); mercury is used in high-temperature environments (523-923K); sodium is selected for even higher temperature ranges (873-1473K); and indium is used in extremely high-temperature conditions (2000-3000K). In most room-temperature application scenarios, heat pipes usually use ammonia (213-373K), methanol (283-403K), ethanol (273-403K), or water (298-573K) as the working fluid. Among these, copper/water heat pipes can operate stably within a temperature range of 20-150°C. 05 The Application Fields of Heat Pipes With their excellent heat transfer performance, heat pipes have shined in numerous fields. In traditional industries such as aerospace and military engineering, heat pipes have always played an indispensable role. When heat pipes were introduced into the radiator manufacturing industry, they completely revolutionized traditional radiator design concepts. This allowed people to move away from the traditional model of relying solely on high-airflow fans to achieve better heat dissipation. Instead, a new heat dissipation model emerged, which combines low-speed, low-airflow fans with heat pipe technology. This has created conditions for the quiet operation of electronic devices such as computers and enabled the wide application of heat pipes in the electronics and other fields. In addition, heat pipes also perform excellently in solving heat transfer problems in special environments. For example, during the construction of China's Qinghai-Tibet Railway, heat pipes were cleverly used to address the problem of subgrade damage caused by the seasonal expansion and contraction of permafrost. The unassuming gray rods alongside the railway are the heat pipes playing a key role. Unlike the heat pipes in laptops and spacecraft, which rely on capillary action to return liquid from the heat-releasing end to the heat-absorbing end, the heat pipes used on the subgrade of the Qinghai-Tibet Railway are wickless gravity heat pipes. They have no wick inside and instead rely on gravity to return the liquid. The advantage of such gravity heat pipes is that they can be made very long, overcoming the limitation that the liquid return distance in capillary heat pipes is restricted by capillary action. Heat pipes also play an important role in China's lunar and Mars exploration projects. The temperature difference between day and night on the lunar surface is extremely large. In such extreme environments, since the first phase of the lunar exploration project, China has been committed to researching the use of heat pipes coupled with phase change materials to store energy during the day and release it at night, ensuring the normal operation of spacecraft. Today, from computers in space stations to manned spacecraft, none can do without technologies such as heat pipes to ensure the safety and stability of their operations. With the continuous advancement of technology, the computing power of artificial intelligence has experienced explosive growth, and the power consumption and heat generation problems of large data centers have become increasingly prominent. Under such circumstances, heat pipes have demonstrated revolutionary potential in solving heat dissipation problems in small spaces. At the same time, the application of heat pipes is constantly expanding toward extreme directions, such as in ultra-high temperature, ultra-low temperature, and other special occasions. For instance, heat pipe scalpels can operate at a low temperature of -100°C, using low temperatures to perform precise treatment of lesions. In addition, the shape of heat pipes is no longer limited to the traditional tubular form. To save space, heat pipes used in aircraft have evolved into thin-layer "heat sheets." In short, wherever heat needs to be controlled and transferred, there may be room for the application of heat pipes. "The 'Invisible Heroes' in the Tech World! How Does Heat Pipe Technology Change Our Lives?" 06 Breakthroughs in China's Heat Pipe Research Ma Tongze, a pioneer in China's heat pipe technology research field, led his team to scale new heights in heat pipe research and achieve a series of remarkable breakthroughs, relying on his outstanding leadership and profound academic attainments. Looking back to 1968, it was a milestone moment in the history of China's heat pipe research. Under Ma Tongze's leadership, China successfully developed the first water heat pipe prototype. This achievement, like a bright star, illuminated the path for China's heat pipe research and laid a solid foundation for subsequent in-depth exploration. Time moved to 1972, and another inspiring breakthrough followed. China's first high-temperature liquid metal sodium heat pipe successfully passed tests. This major progress not only demonstrated China's strength in heat pipe technology research but also marked that China had successfully entered a new stage in this field. After that, the heat pipe research team led by Ma Tongze did not rest on their laurels but continued to move forward, overcoming one technical difficulty after another. They skillfully applied heat pipe technology to many fields, demonstrating the wide applicability and great potential of heat pipe technology. In the aerospace field, heat pipes provided reliable guarantees for the temperature control of spacecraft; in the industrial field, they helped improve energy utilization efficiency and reduce production costs; in the electronics field, they effectively solved the heat dissipation problem of equipment and improved product performance. These application results not only brought significant economic benefits to related industries but also promoted the overall improvement of China's scientific and technological level. In this process, the heat pipe research team achieved a number of scientific research results and won high recognition and praise from the industry. Behind these achievements lies the hard work and unremitting efforts of Ma Tongze and his team, who worked day and night. Ma Tongze not only made outstanding achievements in the academic field but also was highly respected for his noble character. He attached great importance to the training of students' basic skills, striving to ensure that every student could master the operation of various instruments and meters proficiently and clearly understand the advantages and shortcomings of different instruments. In practice, he always took the lead and personally guided students to complete every work detail. For example, to ensure the measurement accuracy of thermocouples, after students welded the thermocouples by hand, Ma Tongze would carefully measure the error of each one. Ma Tongze also cared for his students in every possible way, always paying attention to their living conditions. When he learned that the research institute had limited conditions and students had difficulty taking a bath, he went to great lengths to communicate and coordinate with the institute's leaders many times. Finally, he successfully solved this problem, creating better living conditions for the students. When facing academic misconduct, Ma Tongze held a firm stance and did not back down. He resolutely resisted academic fraudsters and safeguarded the purity and fairness of academics. Once, when someone promoted the so-called ZGM medium tube as having magical effects, attracting a large number of investors to inject capital and holding seminars, Ma Tongze stepped forward and took the lead in writing an open letter to expose the true nature of this pseudoscience, demonstrating the justice and responsibility of a scholar. Although Mr. Ma Tongze has passed away, many of the talents he trained are still active in the heat pipe field, inheriting and carrying forward his academic ideas and scientific research spirit. They shine in their respective positions and contribute to the continuous development of China's heat pipe technology. Finally As a high-performance heat transfer component, the heat pipe is like a bright star, shining brilliantly in many fields and playing a pivotal role. From the precise temperature control of aerospace equipment to the efficient heat dissipation of electronic devices, and then to the optimized use of energy in industrial production, the application of heat pipe technology is ubiquitous, and its importance is self-evident. With the rapid development of science and technology, the development and application fields of heat pipe technology are still continuously expanding and innovating. New materials, new structural designs, and more advanced manufacturing processes continue to emerge, injecting a steady stream of vitality into the performance improvement and application expansion of heat pipe technology. China has achieved remarkable achievements in the field of heat pipe research. This not only demonstrates the wisdom and efforts of Chinese researchers but also provides strong technical support for the development of related industries in China. However, the development of science and technology is endless. In the future, we have reason to believe that with the unremitting exploration and innovation of Chinese researchers, heat pipe technology is expected to achieve major breakthroughs in more cutting-edge fields and create more miracles for China's scientific and technological progress and economic development. We are full of expectations and firmly believe that in the near future, heat pipe technology will set off a new wave of science and technology in China and even around the world, contributing more wisdom and strength to the better life of mankind and the sustainable development of society.