What happens to refrigerants as they Expand in the evaporator?

When refrigerants expand in the evaporator, they absorb heat from their surroundings, which is a fundamental principle of the refrigeration cycle. As the refrigerant passes through the expansion device, it decreases in pressure and temperature as it transitions from a liquid phase to a vapor phase. This evaporation process absorbs heat from the environment, allowing the refrigerant to draw heat from the space being cooled.

This heat absorption is crucial for the efficiency of the refrigeration system, as it cools the air or liquid in the refrigerator or air conditioning unit. The correct understanding of this process highlights the role of the evaporator in the overall heat exchange process of HVAC systems, solidifying the concept that heating absorption from an external space is essential for achieving desired cooling effects.

The other choices do not accurately describe what occurs during the expansion of refrigerants in the evaporator. Refrigerants do not reject heat during this stage; instead, their pressure decreases, which naturally aligns with the expansion process but does not describe the specific heat transfer taking place. Additionally, during this stage, refrigerants do not condense into a liquid; rather, they transition from a liquid to a vapor as they absorb heat.