Organic heat transfer fluids are a general term for organic substances used as heat transfer media. They include organic media used for indirect heat transfer, such as heat transfer fluids, hot oils, organic heat transfer carriers, and heating media. Based on chemical composition, they can be divided into synthetic organic heat transfer fluids and mineral oil-based organic heat transfer fluids. Based on boiling range, they can be classified as vapor-phase organic heat transfer fluids and liquid-phase organic heat transfer fluids.