What type of substance is lithium bromide considered in refrigeration?

Lithium bromide is classified as an absorbent in refrigeration applications, particularly in absorption refrigeration systems. In these systems, lithium bromide absorbs water vapor from the refrigerant, which typically is water in absorption cooling applications. This process occurs in the evaporator, where the refrigerant vapor is absorbed into the lithium bromide solution.

The use of lithium bromide as an absorbent is advantageous due to its ability to absorb large amounts of water vapor and its low vapor pressure, which enhances the efficiency of the cooling cycle. Unlike conventional refrigerants that circulate in vapor and liquid form, in an absorption system, the absorbent helps carry the refrigerant through the cycle by absorbing and releasing it as needed. This unique property is what distinguishes lithium bromide from other substances, such as refrigerants which operate by undergoing phase changes between liquid and gas states to provide cooling.

Understanding this role is fundamental to grasping how absorption refrigeration systems function and the specific application of lithium bromide within those systems.