What is the function of the heat exchanger in an absorption system?

In an absorption refrigeration system, the heat exchanger plays a crucial role in the process of transferring heat between different working fluids. The purpose of the heat exchanger is to facilitate the transfer of thermal energy, optimizing the efficiency of the system.

The correct option indicates that weak liquor, which is a dilute solution of the absorbent, is used to heat the strong liquor, which is a more concentrated solution. This process helps in recovering some of the energy that would otherwise be lost, allowing the strong liquor to gain heat and become even more concentrated. This is essential in the operation of an absorption refrigeration cycle, as it enhances the system's overall efficiency by minimizing the energy consumption required to regenerate the strong liquor.

Heat exchangers effectively reduce the amount of fuel or energy needed by transferring waste heat from hot fluids to cooler liquids, and in this case, using the weaker solution to preheat the stronger one illustrates this principle very well. In contrast, the other options do not accurately describe the primary function of the heat exchanger in this context.