Heat transfer fluids are substances used to facilitate the transfer of heat from one area to another in industrial processes, heating and cooling systems, and other applications. These fluids are often liquids or gases that have high thermal conductivity and specific heat capacities, allowing them to efficiently absorb and transfer heat. Common heat transfer fluids include water, oils, refrigerants, and molten salts. These fluids are used in a wide range of industries, including automotive, aerospace, manufacturing, and energy production, to regulate temperatures, maintain equipment efficiency, and prevent overheating. Research in this area focuses on developing new heat transfer fluids with improved performance, stability, and environmental sustainability.