The Difference Between a Chiller and a Cooling Tower

Types of Chillers and Cooling Towers

• Cooling towers are designed in two major types: mechanical draft and natural draft. Mechanical draft cooling towers rely on fans to pull cool air into the system to remove the heat from water. Natural draft towers, commonly seen with a nuclear power plant, use the exhaust air funneled into a tall chimney. As the air rises, it provides cooling properties. Chillers are designed as radiators, which are either water-cooled or air-cooled. Air-cooled chillers need less maintenance than water-cooled chillers, while the latter consumes less power than the former.

Major Components

• The major components of a cooling tower are the basin and pumps. The distribution basin collects the water discharged from the circulating water system. Pumps supply water to the cooling towers, and create the water flow that facilitates cooling. Chillers utilize compressors, evaporator heat exchangers and condenser heat exchangers. The condenser heat exchanger is the major component that rejects heat from the chillers to air.

Applications and Usages

• Cooling towers are generally used to provide cooled water to electric power generation and mechanical processes. Power plants that are located near lakes and rivers use cooling towers to cool the circulating water, which has been heated in the condenser. Chillers are used in applications, which are not affected by the extra heat discharged by it. In fact, the additional heat is used to warm the plant during the winter. The most common chiller applications include use in the plastic industry and refrigeration applications.

Power Consumption Efficiency

• A cooling tower uses pumps to circulate the water supply. The pumps consume a lot of power. The fans used in cooling towers also consume electrical power; however, the cooling towers provide significantly greater cooling capacity, which translates into greater energy-efficiency cooling. Chillers are driven by compressors and heat exchangers, and therefore are not as energy efficient. When comparing chillers, water-cooled chillers offer optimum efficiency when compared to the level of power consumption. A wet surface transfers heat better than a dry surface; hence, a water-cooled chiller consumes 10 percent less power than air-cooled chillers.