🔍 Key Concepts

• Hot gas bypass purpose in a direct-expansion chiller (what side pressure it affects and under what load conditions it is used) • Liquid injection to compressor suction: why we cool suction gas and when the compressor/motor is at greatest risk of overheating • Difference between high load and low load conditions on evaporator pressure and chiller freeze-up risk

💭 Think About

• When the ship’s cooling load on the chiller is very light, what happens to evaporator pressure and refrigerant temperature? How could hot gas bypass help that? • When is the hermetic compressor motor working its hardest and generating the most heat — at high load or low load? In that situation, what do we want liquid injection to do to the suction gas? • Look at figure A and trace where the hot gas line and the liquid injection line connect. Based on that piping, which control acts during light load and which during heavy load?

✅ Before You Answer

• Verify under which condition (low load vs high load) the evaporator is most likely to drop below freezing and need pressure support from hot gas. • Verify under which condition the compressor windings are hottest and need cooler suction vapor from liquid injection. • Check that the statement you choose matches BOTH: correct load condition for hot gas bypass AND correct load condition for liquid injection.