What happens to vapour after it has evaporated and is further heated?

• A. The vapour condenses back into a liquid
• B. The vapour enters a superheated state
• C. The vapour pressure drops
• D. The vapour temperature stabilizes

Answer: (B)

When a vapour evaporates and is subsequently heated further, it transitions to a superheated state. In this context, superheating refers to the condition where the vapour is heated beyond its boiling point at a given pressure without changing its state back into a liquid.

In many refrigeration and air conditioning systems, this phenomenon is crucial for the efficient operation of the compressor, which requires superheated vapour to function optimally. The reason for this is that superheated vapour has a higher temperature and lower density than saturated vapour, contributing to effective heat transfer and preventing liquid refrigerant from entering the compressor.

Additionally, achieving a superheated state ensures that the refrigerant is entirely in gaseous form, minimizing the risk of compressor damage that could occur if liquid refrigerant were to enter the compressor. This process is fundamental to understanding thermodynamic cycles in refrigeration and air conditioning technologies, emphasizing the significance of superheating for system performance.