How do absorption refrigeration systems utilize waste heat?

Absorption refrigeration systems utilize waste heat primarily to evaporate water from the weak lithium bromide solution. In these systems, a refrigerant (typically water) and an absorbent (often lithium bromide) are used in a cycle where heat is the driving force.

When waste heat is introduced into the system, it raises the temperature of the weak lithium bromide solution. This increase in temperature allows water to evaporate from the solution, effectively causing it to transition from a liquid to a gaseous state. The vaporized refrigerant then moves through the system, ultimately aiding in the cooling process. This method harnesses waste heat, making it a highly efficient and sustainable approach for refrigeration, especially in applications where heat is readily available, such as in industrial processes or from power generation.

The other options do not accurately describe the main function of waste heat in absorption refrigeration systems. For instance, while heating the lithium bromide solution is part of the process, it is specifically about the evaporation of water that effectively utilizes that waste heat for the refrigeration cycle. The other functions mentioned, such as powering compressors or maintaining system pressure, are more characteristic of vapor-compression systems rather than absorption systems.