MIDLAND, Mich. - The Dow Chemical Co. reported demand growth for its heat transfer fluids for secondary loop refrigeration applications of approximately 120 percent in 2008. And according to the company, demand for 2009 is also expected to be brisk as more supermarkets utilize secondary loop refrigeration to minimize energy consumption and environmental impact.
Secondary loop refrigeration began to grow in popularity about 10 years ago, but with energy prices soaring and the need to reduce the amount of greenhouse gases an increased priority, more stores are using efficient and environmentally friendly secondary loop systems for in-store refrigeration, said Dow. And those stores that have not adopted secondary loop refrigeration are seriously considering it, as revealed in a survey of the industry released by Dow Performance Fluids.
In traditional stores, each refrigerated food display case has its own refrigeration unit. By using secondary loop efficiencies, the number of individual refrigeration units is reduced to a single cooling unit. Secondary loop refrigeration systems using heat transfer fluids can help eliminate the need for numerous individual direct expansion refrigeration units, thus reducing the amount of ozone-depleting refrigerants used and potentially leaked into the environment, said Dow. Having fewer refrigeration units also reduces energy consumption. The energy saved depends on the size of the store and the number of refrigeration units replaced.
Secondary loop refrigeration systems can be used to cool meat, dairy, produce, and other medium temperature chilled food display cases. The system is designed to reduce the use of refrigerant and limit the potential for leaks into the environment. The secondary loop approach utilizes an abbreviated expansion loop (as compared to the more traditional direct expansion system) and a larger, low pressure secondary loop distribution system filled with propylene glycol based heat transfer fluid.
In addition to cutting refrigerant emissions, these types of systems are also said to improve display case cooling performance. The secondary loop system provides more evenly distributed and constant temperature refrigeration to chilled food display cases throughout the store at equivalent or lower operating energy expenses, said Dow. The primary refrigerant charge volume requirement is 65 to 85 percent lower, while the more compact direct expansion loop helps reduce the number of copper valves, fittings, and connections in the overall system. Many respondents to the Dow survey said the low pressure secondary loop, which typically utilizes ABS pipe, significantly reduces the potential for leaks, generating fewer emissions. Furthermore, said the company, studies show that on average secondary loop systems have up to 50 percent lower annual maintenance costs when compared to more traditional systems.
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