How do evaporative condensers achieve heat rejection?

Evaporative condensers achieve heat rejection primarily through the process of evaporation of water. In these systems, ammonia or another refrigerant enters the condenser as a vapor and passes through a set of coils or a surface where it is exposed to water. The heat from the vapor refrigerant is transferred to the water, which causes some of the water to evaporate.

As the water evaporates, it absorbs a significant amount of heat from the refrigerant, facilitating the cooling and condensation of the vapor into a liquid. This process not only removes heat from the refrigerant effectively but also contributes to the cooling effect through the latent heat of vaporization. The continuous circulation of water keeps the system efficient, making evaporative condensers highly effective for heat rejection in industrial ammonia refrigeration systems.

Other methods mentioned in the options, such as mechanical means, chemical reactions, or thermal expansion, do not directly explain the operational principles of evaporative condensers. Mechanical means might be involved in some refrigeration systems, but they are not the primary mechanism in evaporative condensers. Chemical reactions are unrelated to the heat rejection process in this context, and thermal expansion typically concerns changes in pressure and temperature rather than serving as a means of heat rejection.