Benefiting from the excellent thermal conductivity and flow properties of liquid metal, liquid metal convection cooling offers a new solution to the high heat flux thermal management of electronic devices and equipment. In this paper, the heat transfer and flow characteristics of liquid metal convection were introduced. Compared to traditional fluids, the high thermal conductivity of liquid metals resulted in lower overall thermal resistance, and the heat transfer performance was better. The relevant research progress of driving technology, hybrid cooling technology and heat transfer enhancement technology based on liquid metal convection were summarized. The application status of liquid metal convection in the field of electronic equipment cooling was briefly described. Finally, the challenges and development prospects of liquid metal convection cooling were discussed.

Flat heat pipe, due to its advantages of high heat transfer efficiency, great temperature uniformity, and safety and reliability, has become one of the important options for spacecraft thermal control. Optimization of wick structure is an important method to improve the flow and heat transfer performance of flat heat pipe. For the design of wick structures, the method of designing high performance wick structures was revealed, and guidance was provided for the selection and application of macromeso-micro multiscale numerical model. For wick surface modification, the importance to improve nanostructure mechanical stability, adjust heat transfer mechanism and carry out numerical simulation research was emphasized. To solve the problems of heat dissipation and high radiation in space environment, the development directions of flat heat pipe in spacecraft thermal control were figured out, and the shortcomings of current research were analyzed.

To reduce the energy consumption of electric vehicle heating system, a cascade heating system with multiple heat sources distributed based on waste heat recycling was designed. Firstly, the thermal load of the carriage was analyzed and calculated, providing a basis for the selection and matching of heating components. To explore the heating sequence and heat production, a heat release model for the power battery, drive motor, and controller was built, and simulation analysis using ANSYS was conducted to explore heat release laws. Considering the impact of heat released by drivers and passengers on the temperature inside the vehicle, a pyroelectric infrared technology was designed to detect the number of drivers and passengers, in order to estimate their heat release. A cascade collaborative heating method with multiple heat sources distributed was designed, and the optimal heating method could be selected in a timely manner based on the heat release law of the heat sources, environmental temperature, and the number of drivers and passengers. Finally, low-temperature tests were conducted on the heating air system, and the results showed that after operating for 2 hours at an ambient temperature of -22℃, compared with traditional electric vehicle heating, the proposed method saved 31.1% and 63.6% energy, respectively, verifying its superiority.

The mechanical properties and pore structure changes caused by the circulation of low-temperature cooling medium in high-temperature granite are of great significance to further understand the high-temperature rock engineering such as dry hot rock development. Taking Zhangzhou granite as the research object, uniaxial compression tests and micro pore structure tests were conducted to analyze the evolution of different characteristic parameters with the number of cycles, and to explore the degradation mechanism of granite after high-temperature and liquid nitrogen cycling. The experimental results showed that during high temperature and liquid nitrogen cycling treatment, the small pores inside the granite exhibited random and dynamic distribution, while the large pores exhibited widespread distribution. As the number of cycles increased, the nuclear magnetic porosity and peak strain of granite gradually increased, while the compressive strength and elastic modulus gradually decreased. The fracture mode of untreated granite was mainly shear or splitting failure with a single fracture surface, while the fracture mode of granite after high temperature and liquid nitrogen cycling was mainly shear and splitting failure with multiple fracture surfaces. The differences in mineral thermal expansion coefficients and changes in strength and pore structure were key factors inducing damage and deterioration of granite under high temperature and liquid nitrogen cycling.

In this article, the magnetic power loss of NdFeB magnetic material was calculated by combining experiment and simulation. The results showed that the magnetic power loss of NdFeB thermoseed in the magnetic field with frequency of 21~29 kHz and magnetic induction intensity of 2.7~3.7 mT was higher, and the thermal volumetric power density was in the range of 2.39×10⁶ W/m³~5.54×10⁶ W/m³ under the given magnetic field condition. The results were applied to the simulation of magnetic induction hyperthermia. The simulation results showed that the effective hyperthermia boundary of a single NdFeb thermoseed was ellipsoidal, with the short half-axis of 12.9 mm of and the long half-axis of 17.6 mm for the maximum effective hyperthermia range under the given magnetic field condition, indicating that NdFeB thermoseed could reach the heat generation power required for hyperthermia under low magnetic field frequency and magnetic induction intensity, which provided data support for the application of NdFeB material in magnetic hyperthermia.