FDNY CoF – Temporary Certificate of Fitness Card (Z-51) Practice Test

The most critical reason for sub-cooling refrigerant in the condenser is to ensure that a pure liquid refrigerant will enter the device. Sub-cooling refers to the process of cooling the refrigerant below its saturation temperature after it has condensed. This step is essential because it allows for the removal of any remaining vapor in the refrigerant mixture, ensuring that only liquid enters the expansion device.

Entering the expansion device with a fully liquid refrigerant is vital for the efficient and effective operation of the refrigeration cycle. If vapor makes its way into the expansion device, it can lead to incomplete phase change and inefficiencies in heat absorption within the evaporator. Ensuring a pure liquid also helps in optimizing the performance of the system and prevents potential mechanical issues such as compressor damage or increased wear and tear, leading to a longer lifespan for the equipment.

In summary, sub-cooling protects the integrity of the refrigerant phase and enhances the overall functioning of the refrigeration system by ensuring that only liquid refrigerant is fed into the expansion device.