Natural gas, as one of the three major energy sources, has increasingly gained favor both domestically and internationally in recent years. After liquefied natural gas (LNG) is converted, its volume decreases by about 1/625, which offers significant advantages for storage and transportation. However, when users consume natural gas, LNG needs to be vaporized before use. The normal pressure storage temperature of liquefied natural gas is 111K (-162°C), and the process of vaporizing it and reheating it to the normal temperature of 300K (around 27°C) will release a large amount of cold energy, approximately 883 kJ/kg. The recycling of this cold energy is of great significance for improving the efficiency of LNG use and saving energy consumption. Project Overview: Currently, the utilization of cold energy from liquefied natural gas can be applied in various fields and scenarios, such as thermoelectric power generation, air separation, refrigeration, freezing, and the production of dry ice. In addition to low-temperature utilization, according to the principle of cascade utilization of cold energy, From the vaporization point to room temperature, the cold energy of LNG can be recycled and utilized in different stages for applications such as low-temperature quick-freezing storage (-60°C), low-temperature refrigeration storage (-35°C), high-temperature refrigeration storage (-18°C), as well as for pre-cooling warehouses for fruits and vegetables and central air conditioning systems (0°C to 10°C). The research team on LNG cold energy utilization at the Institute of Refrigeration and Low Temperature Engineering, Xi'an Jiaotong University, is leading domestically in this field and has a solid foundation and achievements. Currently, the team mainly possesses important theoretical support and key application technologies in the following areas: (1) For liquefied natural gas vehicles (LNGV) and refrigerated transport vehicles (cold chain) or cabin air conditioning technology; Vehicles that use natural gas as fuel are divided into CNG (Compressed Natural Gas) vehicles and LNG (Liquefied Natural Gas) vehicles. The latter, due to its larger volumetric capacity per unit volume, can provide longer-distance power for vehicles. Secure and reliable, gradually accepted by the automotive market. (2) LNG cold energy is used in air separation plant processes. It can provide a low-temperature cold source for the air separation process, inputting a large amount of high-quality low-temperature cold energy into the system, thereby reducing the energy consumption of the air separation process and achieving the goal of energy saving and efficiency enhancement. Research achievements: The LNG cold energy recycling technology studied in this project has applied for multiple invention patents, conducted simulation experiments on refrigerated trucks, where the cooling capacity can fully meet the requirements. At the same time, a series of studies have been carried out on the refrigeration truck's cold storage technology and the temperature field inside the box, realizing the efficient recycling of LNG cold energy. Project further development plan: This research group will further carry out experimental research, theoretical basic research, and more important application research on LNG cold energy recovery. With the hope that this technology can be successfully applied to automotive air conditioning as soon as possible. In cryogenic refrigeration trucks and large-scale air separation processes: (1) Improve the LNG refrigeration truck's cold energy recovery system; (2) Research on refrigeration truck's cold storage technology; (3) Improve the car compartment air conditioning technology that utilizes LNG cold energy; (4) Strive to apply and promote the LNG cold energy recovery technology in the air separation industry.