What is the process of varying the amount of refrigerant pumped by the compressor called?

The process of varying the amount of refrigerant pumped by the compressor is referred to as unloading. This is an important feature in refrigeration and air conditioning systems, as it helps to adjust the system's capacity to match the current cooling load. By reducing the amount of refrigerant circulating through the system, unloading helps to prevent excess cooling or overcapacity, thereby improving efficiency and reducing operational costs.

Unloading is typically achieved through various methods such as using suction pressure control or electronic controls that can modulate compressor operation. This process optimizes performance and energy use while maintaining a consistent temperature in the space being conditioned.

In contrast, other processes mentioned do not pertain to the adjustment of refrigerant flow. Compression refers to increasing the pressure of the refrigerant, recovery involves reclaiming refrigerant from a system for storage or recycling, and condensation relates to the phase change of the refrigerant from gas to liquid upon releasing heat. These processes serve distinct functions in the refrigeration cycle and do not directly involve the modulation of refrigerant flow by the compressor.