Changing the pressure upon a refrigerant changes?

The correct choice highlights that changing the pressure of a refrigerant affects both the boiling and condensing temperatures. This relationship is due to the properties outlined in the refrigerant's psychrometric chart or pressure-temperature chart, which defines how a refrigerant behaves under different conditions.

When the pressure of a refrigerant is increased, its boiling temperature also rises. This means that a refrigerant can remain in liquid form at higher temperatures when under higher pressure, which is crucial in various refrigeration and air conditioning applications. Conversely, if the pressure decreases, the boiling temperature drops, allowing the refrigerant to vaporize at lower temperatures.

Similarly, the condensing temperature behaves in a directly proportional manner to pressure changes. An increase in pressure will lead to a higher condensing temperature, meaning the refrigerant will release heat and condense into a liquid at a higher temperature than it would at a lower pressure. This interaction is critical in understanding cycles in refrigerant management.

This robust relationship between pressure, boiling temperature, and condensing temperature is fundamental to the principles of thermodynamics employed in refrigeration and air conditioning systems. It illustrates how manipulating pressure can directly impact the efficiency and operational parameters of these systems.