Dry vs. Wet Compression:

If the Carnot vapour cycle follows the path 1-2-3-4, then there is dry compression of the refrigeration vapour as the refrigerant is dry saturated on state 1. This kind of compression is needed in the compressor. However, in this case we illustrate that the refrigerant now ought to be compressed isothermally from state 2 to state 3 that is impossible to attain in practice. The alternative path 1'-3-4-5 include a wet compression of the vapour from state 1' to state 3. Wet compression is extremely undesirable as the compressor now ought to deal along two different fluid phases. In addition, the liquid droplets exist in the vapour now would react along the lubricant in the compressor that is highly undesirable. Therefore, we illustrate that both of the paths of the Carnot vapor cycle are not appropriate for use in practical refrigeration systems.