The amount of water used in an evaporative condenser is only a small percentage of that used in a water-cooled condenser of the same capacity, because?

The correct choice highlights the principle of evaporative cooling, which is a key concept in refrigeration and HVAC systems. In an evaporative condenser, water absorbs heat from the refrigerant and subsequently evaporates, transforming from liquid to vapor. This phase change requires a substantial amount of energy, known as latent heat, which enables the evaporative condenser to remove significantly more heat per kilogram of water compared to just sensible heat transfer in a water-cooled condenser.

Because of the evaporation, the amount of water actually needed to achieve the same level of heat removal is much lower. In contrast, a water-cooled condenser primarily relies on direct contact with water to remove heat through sensible heat transfer without the phase change of evaporation, which requires a larger volume of water to achieve similar cooling effects. Therefore, the evaporative condenser’s process allows for efficient heat transfer, using minimal water while effectively cooling the system.

This principle is foundational in understanding refrigeration system efficiencies and water conservation in cooling applications. Thus, the efficiency in removing more heat through evaporation makes the water usage in an evaporative condenser substantially lower than that of a water-cooled condenser of equal capacity.