What is the difference between condenser and evaporator?
Fundamentally there is no difference between condenser and evaporator. Both are just heat exchangers and transfer heat from hot fluid to cold fluid which results in the phase change of working fluid. This transfer of heat happens theoretically at a constant pressure. There is no production or consumption of thermodynamic work in these devices.
A condenser is used to extract the heat from the hot working fluid in the system, change the phase of that fluid by removing the latent heat and transfer this heat to the atmosphere/surroundings.
On the other hand, the evaporator is used to absorb heat from the surroundings and add it into the system. This heat is used as latent heat which changes the phase of the working fluid (from liquid to vapor).
What are the applications areas?
The condenser is used in the vapor power cycle or Rankine cycle. The steam coming out from the turbine after producing work has a significant amount of heat content and according to the second law of thermodynamics, there must be a mechanism in the system to remove the heat from the system. Hence, the condenser is used to remove the heat from the system to the surroundings. The vapor phase of the steam changes into liquid in this process. This working fluid in the liquid phase can easily be pumped to boiler pressure.
The condenser is also used in vapor compression refrigeration systems to remove the heat from the refrigerant which was absorbed in the evaporator and the amount of heat increases at the compression stage. This causes the refrigerant in the high-pressure vapor phase to condense into the high-pressure liquid phase. Theoretically, this process happens under constant pressure. The evaporator works exactly in the opposite way.
Do they produce any thermodynamic work?
These devices do not produce any thermodynamic work as they work in open systems and at constant pressures. For devices working in open systems, the work done is given by the following formula,
As the condenser and evaporator operate theoretically at constant pressure dP=0, the thermodynamic work produced is equal to zero.