How can temperatures inside the evaporator be determined?

How can temperatures inside the evaporator be determined?

• A. By using a pressure-temperature relationship chart
• B. Measuring with a standard thermometer
• C. Referring to a saturation temperature chart
• D. Calculating from ambient conditions

Answer: (A)

The temperature inside the evaporator is dictated by the refrigerant’s pressure during evaporation. In the evaporator, the refrigerant is a saturated mixture at the evaporating pressure, so its temperature equals the saturation temperature corresponding to that pressure. To determine it, measure the evaporating pressure with a gauge on the low-pressure side and look up the corresponding temperature on a pressure–temperature chart for the refrigerant. That saturation temperature is the evaporator temperature. A standard thermometer can’t reliably measure the internal, pressurized, two-phase refrigerant, and ambient conditions don’t set the evaporator temperature; using a pressure–temperature chart directly links the measured pressure to the actual evaporator temperature.

The temperature inside the evaporator is dictated by the refrigerant’s pressure during evaporation. In the evaporator, the refrigerant is a saturated mixture at the evaporating pressure, so its temperature equals the saturation temperature corresponding to that pressure. To determine it, measure the evaporating pressure with a gauge on the low-pressure side and look up the corresponding temperature on a pressure–temperature chart for the refrigerant. That saturation temperature is the evaporator temperature. A standard thermometer can’t reliably measure the internal, pressurized, two-phase refrigerant, and ambient conditions don’t set the evaporator temperature; using a pressure–temperature chart directly links the measured pressure to the actual evaporator temperature.