If lithium bromide is used as an absorbent, what is the refrigerant?

Using lithium bromide as an absorbent indicates that water is the refrigerant in this context. Lithium bromide is widely utilized in absorption refrigeration systems, particularly those that operate with water as the refrigeration medium. In these systems, water evaporates and absorbs heat, creating the cooling effect, while lithium bromide acts as a desiccant to absorb the water vapor, leading to a continuous cycle.

The other substances listed, such as Freon, ammonia, and propane, do not pair with lithium bromide as absorbents in the same way. Freon is a brand name for a class of refrigerants used in vapor-compression refrigeration systems and does not require an absorbent. Ammonia, while it can be used in some absorption systems, typically does not pair with lithium bromide—rather, it is commonly used in ammonia-water solution systems. Propane, being a hydrocarbon, is primarily employed in vapor compression refrigeration systems and does not interact with lithium bromide. Thus, water is the correct answer, as it aligns with the established principles of absorption refrigeration with lithium bromide.