Air-cooled Water Chiller
These types of water chillers have condensers designed to exchange heat from refrigerant to ambient air. They use air as the condensing medium.
An air-cooled condenser unit typically features finned coils. This increases the surface area of the condenser in contact with air. One or more fans are used to blow air over the finned coil to further improve heat transfer. The amount of heat rejected by an air-cooled condenser depends on the rate of airflow over the coils and the air's dry-bulb temperature.
The advantage of using air-cooled water chillers is their simplicity and low cost. They can be installed as stand-alone units without requiring additional infrastructures such as cooling water supply lines and cooling towers.
Water-cooled Water Chiller
As the name suggests, water-cooled water chillers use water as the condensing medium. Since these types of chillers also use water as their cooling medium, two water loops exist in the system.
Water-cooled condensers typically operate with a cooling tower. Cooling towers are heat exchangers, but instead of the usual conduction-convection type of heat exchangers, it generates cooling by bringing water and air into contact. They supply cooling water to the condenser unit which is used to cool the refrigerant.
Water-cooled chillers are used in large industrial plants where a cooling water supply is readily available. Cooling is provided to the condenser at a much higher efficiency compared to air-cooled types.