The objective of a mechanical refrigeration system is to remove heat from a space or product, and to reject that heat to the environment in some acceptable manner. Evaporative condensers are frequently used to reject heat from mechanical refrigeration systems. The evaporative condenser is essentially a combination of a water-cooled condenser and an air-cooled condenser, utilizing the principle of heat rejection by the evaporation of water into an air stream traveling across the condensing coil.
Evaporative condensers offer important cost-saving benefits for most refrigeration and air-conditioning systems. They eliminate the problems of pumping and treating large quantities of water associated with water-cooled systems. They require substantially less fan horsepower than air-cooled condensers of comparable capacity and cost. And most importantly, systems utilizing evaporative condensers can be designed for a lower condensing temperature and subsequently lower compressor energy input, at lower first cost, than systems utilizing conventional air-cooled or water-cooled condensers.
The evaporative condenser offers a number of important advantages over other condensing systems:
- Low system operating costs Condensing temperatures within 15°F of design wet-bulb are practical and economical, resulting in compressor horsepower savings of 10% or more over cooling tower/condenser systems and more than 30% over air-cooled systems. Fan horsepower is comparable to cooling tower/condenser systems and is about one-third that of an equivalent air-cooled unit. Because of the low pumping head and reduced water flow, water pumping horsepower is approximately 25% of that required for the normal cooling tower/condenser installation.
- Initial cost savings The evaporative condenser combines the cooling tower, condenser surface, water circulating pump, and water piping in one assembled piece of equipment. This reduces the cost of handling and installing separate components of the cooling tower/condenser system.
- Since the evaporative condenser utilizes the efficiency of evaporative cooling, less heat transfer surface, fewer fans, and fewer fan motors are required resulting in an initial material cost savings of 30 to 50% over a comparable air-cooled condenser.
- Space saving The evaporative condenser saves valuable space by combining the condensing coil and cooling tower into one piece of equipment, and eliminating the need for large water pumps and piping associated with the cooling tower/condenser system.
Evaporative condensers require only about 50% of the plan area of a comparable sized air-cooled installation.