To vary the specific capacity of an absorption refrigerating plant, which regulation should an operating engineer make?

The correct choice involves adjusting the flow of steam to the generator and regulating the expansion valve. In an absorption refrigeration system, the generator plays a crucial role as it is where the refrigerant is vaporized using heat, often supplied by steam. By varying the flow of steam to the generator, the engineer can control the amount of heat applied to the system, which directly affects the refrigeration cycle's efficiency and capacity.

Additionally, the expansion valve's adjustment is critical, as it regulates the flow of refrigerant into the evaporator, influencing the pressure and temperature of the refrigerant. This combination allows for fine-tuning the system's cooling capacity, optimizing performance based on the desired application or load requirements.

This approach is essential for maintaining efficient operation and achieving effective temperature control in the refrigeration process, making it a key function for an operating engineer in managing absorption refrigerating plants.