This blog post is an excerpt from a larger article on Custom Cooling Solutions published in the August 2011 issue of Process Heating Magazine – click here to see the entire article.
Free cooling, a method that uses low ambient air temperatures — by way of an air fluid cooler — to cool process water, is making a buzz in the process cooling world, and for good reason. Simply put, when the ambient temperatures rise in the summer, a chiller is used to cool the process; likewise, when the temperatures fall in autumn, winter and spring, the chiller is bypassed and the air fluid cooler is used at much lower operating costs due to the energy savings (click here to see a drawing of a standard free cooling system). Employing a free cooling process design, a facility can save money by reducing utility consumption and saving energy.
Of course there is a tradeoff — initial investment cost goes up. When free cooling is employed, a chiller and air fluid cooler must both be purchased, which raises the cost of the job significantly. However, if you can muster the foresight and reach out to an expert in the field to do the energy-saving calculations, you could find that these units typically have a payback of one to two years.
For instance, a free cooling system General Air Products designed for a glass manufacturer in Pittsburgh. Before free cooling, their glass manufacturing process involved the consumption and elimination of a large amount of city water used to cool the glass when it came out of the ovens. Not only was the company being charged for all of the water they consumed but the sewage authority began charging them for the water that they were discharging because it was such a large volume.
Our process cooling experts recommended a closed-loop, free cooling system following a thorough examination of the process as it would be the total cost of ownership solution. The completely integrated cooling system included a chiller, a fluid cooler, two pumping stations, a thermocouple-operated three-way valve and dual 2,000-gal holding tanks (click here to see a drawing of this specialized free cooling set up).
The process now consumes far less water, and they are discharging almost none. The process water is recycled through the cooling loop and stored in the holding tanks. In the summer, the water is cooled by the chiller; during most of the rest of the year, the water is cooled by the air fluid cooler. Their process is more efficient and they are saving real money today, resulting in a short return on investment.
Free cooling requires more upfront cost compared to the purchase of just a chiller, but this type of equipment can last up to 15 years. With the cost of utilities going up, especially for water, a free cooling consultation is a good idea.
For more information on how custom cooling can deliver solutions see our article published in Process Heating magazine, visit the custom equipment section of our web site or contact us via email or by calling 800-345-8207 to speak directly to a process cooling expert!