By Michael Crocker, Director of Engineering at CQM Systems
Cooling towers provide cooling for air-conditioning, manufacturing processes, or power generation by utilizing the evaporation of water to transfer heat from the process or building to the atmosphere. Therefore, cooling towers consume significant amounts of water and the cooling system is often a building’s largest energy consumer during the cooling season. The following best practices and suggestions will help ensure that you are maximizing energy efficiency in your cooling system.
In order to understand how to optimize cooling tower efficiency, one must understand the basics of cooling tower operation. The equation for the water balance on a cooling tower is below, as well as definitions for the basic terms utilized in cooling tower discussions:
Makeup = Evaporation + Blowdown + DriftMakeup:In order to maintain the cooling system in proper working order, all water leaving the system must be replaced.This incoming water is referred to as makeup.Evaporation:Water that evaporates in the cooling tower and is rejected to atmosphere as vapor.Evaporation provides the necessary cooling for the system.Blowdown:When water evaporates from the system, the dissolved solids and minerals are left behind.Blowdown is water that is purposefully drained from the system to remove dissolved or suspended solids and prevent scale and corrosion problems in the cooling system.Drift:A very small amount of water will escape the cooling tower as mist or water droplets in the air, and is referred to as drift.Compared to evaporation or blowdown, water loss due to drift is insignificant, but can be a factor at the highest levels of water conservation efforts.
Cooling Tower Energy Efficiency
Maximizing the energy efficiency of a cooling system requires evaluation of the entire cooling system (cooling tower, chiller, heat exchangers, etc.) and can often be significantly improved by maximizing the cleanliness of the heat transfer surfaces in the tower and cooling system heat exchangers.
These simple tips and tactics to ensure your cooling tower is operating efficiently can help you significantly improve the energy efficiency of your cooling system. A 1000-ton cooling system that achieves 5% efficiency improvements can save over 90,000 kW-hrs and almost $10,000 each year, and the corresponding sustainability impacts will make you feel good about being green while saving some green!
Michael Crocker is the Director of Engineering at CQM Systems. He has provided operations engineering and project management expertise for industry leaders such as BASF, Michelin, and CH2M Hill. He earned his B.S. in Chemical Engineering from Clemson University and M.B.A. from Portland State University. Learn more energy saving tactics at www.cqmsystems.com.