Improving Thermal Efficiency

by: Mosaic
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Word Count: 682

For low-temperature cooling processes, fluids choices include those developed within the past several years. The fluids can provide high heat transfer coefficients with low viscosities, thereby increasing the overall efficiency of the cooling system. For example, consider a sparkling wine producer that utilizes an open bath using a calcium chloride/water solution at -13 F (-25 C) in the disgorging process. Racks holding approximately 1,200 bottles of sparkling wine travel across the surface of the bath with the wine bottles upside down so that the bottle necks are submerged in the calcium chloride/water fluid. The fluid freezes the yeast in the bottle necks. When the rack reaches the end of the bath, the bottles are opened, and the plug of yeast is removed through the disgorging process. Approximately 10 minutes is required for each rack to pass through the calcium chloride-based water bath so that the yeast is sufficiently frozen. If the fluid in the bath is changed to a potassium formate-based heat transfer fluid, which has a higher heat-transfer coefficient and can be used at a higher temperature (-4 F [-20 C]), less energy will be required to chill the fluid. Simply by switching fluids, the wine producer may be able to obtain a 20 percent improvement in efficiency and 40 to 50 percent drop in labor hours for maintenance due to corrosion and fluid maintenance issues. Heat transfer fluid manufacturers are also investigating the use of nanoparticles to further improve the thermal properties of some coolants. For example, it might be possible to add less than 1 percent of nanoparticles to some fluids to achieve a 20 to 25 percent increase in heat transfer beyond what is achievable with modern high-performance fluids. The change would allow plants to use smaller heat exchangers, chillers and pumps to reduce overall energy consumption. Some technical hurdles remain. For instance, researchers are still trying to optimize the nanoparticle content to avoid increasing viscosity. Still, it is possible that heat transfer fluids containing nanoparticles will be commercially available within the next few years or even sooner. The growing trend toward environmentally friendly technologies and processes is pushing companies to evaluate their processes for environmental impact in addition to productivity and efficiency. While changes to more environmentally friendly materials and processes undoubtedly benefit a processor's public image, bottom-line benefits are a crucial consideration. To address these changing market forces, heat transfer fluids are being developed that offer higher performance with environmental benefits. For example, corn-derived glycol has been developed that is renewable and, according to the manufacturer, provides a 30 percent lower viscosity at low temperatures compared to petroleum-derived propylene glycol. The corn-based fluid also offers thermal stability and similar or improved thermal properties compared to ethylene and propylene glycol fluids. While such fluids are primarily being used in HVAC applications to meet the demand for "green buildings," industrial applications are starting to gain momentum - particularly in food production, where fluid safety is a primary concern. Other applications could follow. Fluid manufacturers also are investigating ways to make high-performance glycol fluids from nonfood waste products, which would provide a way to recycle materials that are currently entering the waste stream. The ethanol industry is driving developments in this process. As the industry develops less expensive methods to convert cellulose to sugar, companies that make corn-derived glycol for heat transfer applications will be able to tap into those advances to create new products. Many modern heat transfer fluids do much more than simply transfer heat. Through carefully formulated chemistries, today's fluids can optimize the efficiency of a cooling operation, minimize wear and tear on machinery, and reduce environmental and safety concerns. Future developments will provide even greater gains in thermal efficiency and environmental sustainability. If your plant has been using the same heat transfer fluids merely out of habit, now would be a good time to evaluate other possibilities. You might be able to substantially increase your plant's productivity, reduce energy costs, improve public image - and position your plant for renewed success.

About the Author

Matthew Mckernan is an expert in the field of heat transfer fluids. With over 20 years experience. http://www.dynalene-uk.com/

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