During an air conditioning service, an automotive technician uses a recovery machine to extract refrigerant. The machine pulls hot, high-pressure refrigerant vapor from the vehicle and continuously removes heat from it until it becomes a subcooled liquid in a storage cylinder. Arrange the following thermodynamic events in the chronological order they occur during this continuous cooling process.
- 1The superheated vapor cools down steadily, decreasing its molecular kinetic energy.
- 2The vapor reaches its specific saturation temperature for the pressure inside the cylinder.
- 3The temperature remains completely constant as latent heat of condensation is released.
- 4The last remaining vapor transforms into liquid, ending the phase change plateau.
- 5The completely liquid refrigerant drops in temperature as sensible heat is further removed.
Answer
The sequence follows a continuous cooling curve: initial sensible cooling of the vapor, reaching the saturation point, the constant-temperature condensation plateau, the end of the phase change, and finally the sensible cooling of the resulting liquid.
As heat is continuously removed from a superheated vapor, its temperature first drops due to sensible heat loss until it reaches the saturation temperature (condensation point). During the actual phase change from gas to liquid, the temperature remains entirely constant as latent heat is released. Once condensation is 100% complete, the temperature of the newly formed liquid begins to drop again.
Step-by-Step Solution
Key Concept
States of Matter and Phase Changes