What accepts the vapor from the evaporator by controlling the suction pressure and compresses the refrigerant to discharge it to the condenser?

• A. Evaporator
• B. Condenser
• C. Expansion device
• D. Compressor

Answer: (B)

In a vapor‑compression ammonia refrigeration system, the part that accepts the low‑pressure vapor from the evaporator, controls the suction pressure, and then compresses the refrigerant to discharge it to the condenser is the compressor.

The evaporator is where heat is absorbed and the refrigerant becomes low‑pressure vapor. The compressor takes that vapor on the suction side, maintains the suction pressure appropriate for the evaporator’s load, and performs work to raise its pressure and temperature. That high‑pressure vapor then moves to the condenser, where it releases heat and condenses. The expansion device is what lowers the high pressure back to the evaporator’s level, so the cycle can continue, while the condenser is responsible for rejecting heat from the high‑pressure refrigerant.