A refrigeration system uses a jet ejector to raise settled oil mixed with refrigerant to the oil pump. If a restriction in the refrigerant flow to the jet ejector develops, what condition may occur?

• A. There may be insufficient head to lift the oil
• B. The oil will overheat
• C. The suction pressure will rise
• D. The discharge temperature will increase

Answer: (A)

The jet ejector creates the lifting head by using a high-velocity refrigerant jet to entrain oil and generate a low-pressure region that carries the oil up to the pump. If the refrigerant flow to the ejector is restricted, the jet loses momentum and the low-pressure head diminishes, so there isn’t enough head to lift the settled oil to the oil pump. The other outcomes aren’t direct results of the restriction: the oil isn’t automatically overheated from the restriction, discharge temperature isn’t set by the lifting head, and suction pressure wouldn’t rise due to reduced entrainment (it would more likely be constrained or fall).