Jet (ejector) refrigeration: In steam-jet or water-jet refrigerators, the working refrigerant used in the evaporator loop is typically which fluid?

Introduction / Context:
Jet (ejector) refrigeration systems exploit high-velocity motive steam or gas to entrain and compress vapor from an evaporator operating at low pressure. The choice of refrigerant in these systems influences achievable temperatures, simplicity, and environmental footprint. A classic configuration uses water as the refrigerant.

Given Data / Assumptions:

• Steam-jet ejector provides suction to the evaporator.
• Evaporator operates under deep vacuum to boil the refrigerant at low temperature.
• System targets chilled water production rather than deep cryogenics.

Concept / Approach:

In water-jet or steam-jet refrigeration, the evaporator contains water as the refrigerant. Under vacuum, water boils at temperatures well below 100°C; at sufficiently low pressure, it can produce chilled water near 5–10°C. The vapor drawn off is compressed by the ejector and condensed, often returning as makeup. This avoids halocarbons and ammonia, simplifying safety and environmental concerns.

Step-by-Step Solution:

Verification / Alternative check:

Design texts consistently describe steam-jet refrigeration systems producing chilled water using water as both refrigerant and chilled medium.

Why Other Options Are Wrong:

Ammonia and freons are used in mechanical vapor-compression systems, not in classic steam-jet water systems. Brine serves as a secondary coolant, not the refrigerant in the evaporator.

Common Pitfalls:

Confusing the chilled secondary loop (often water/brine) with the primary refrigerant in the ejector-based process.

Final Answer:

water