On a pressure-temperature chart for refrigerants, which relationship is shown?

On a pressure-temperature chart for refrigerants, which relationship is shown?

• A. boiling point at constant pressure
• B. saturation temperature at a refrigerant's given pressure
• C. critical temperature
• D. density vs pressure

Answer: (B)

The main idea is the phase boundary between liquid and vapor on a pressure–temperature chart. For any given pressure, the temperature on that boundary is the saturation temperature—the point at which the refrigerant is in equilibrium and can coexist as liquid and vapor. This is exactly what the chart conveys: the saturation temperature at a refrigerant’s given pressure. Above that line, the refrigerant is superheated vapor; below it, it’s subcooled liquid. The critical temperature marks the top end of this boundary where liquid and vapor become indistinguishable, but the chart’s primary relationship is the saturation temperature corresponding to pressure.

The main idea is the phase boundary between liquid and vapor on a pressure–temperature chart. For any given pressure, the temperature on that boundary is the saturation temperature—the point at which the refrigerant is in equilibrium and can coexist as liquid and vapor. This is exactly what the chart conveys: the saturation temperature at a refrigerant’s given pressure. Above that line, the refrigerant is superheated vapor; below it, it’s subcooled liquid. The critical temperature marks the top end of this boundary where liquid and vapor become indistinguishable, but the chart’s primary relationship is the saturation temperature corresponding to pressure.