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 | Energy Saving Intelligent Controls for Refrigeration
A System for Intelligent Control of Defrost Cycles could Result in a Significant Reduction in Energy Consumption for Commercial Refrigeration | |
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| As much as 15% of the power consumed by commercial and industrial refrigeration units can be saved by using intelligent defrost controls. In typical installations, the defrost cycle is initiated at regular intervals during the day by a timer clock that is typically set to accommodate the peak humidity conditions of summer. Thus, the defrost cycle is often begun too soon and runs too long. ADA Technologies has integrated and patented a low-cost frost sensor into a defrost control system that will start the defrost cycle only when necessary and stop it as soon as the ice has been removed from the heat exchanger. The frost sensor, designed to measure the heat transfer from a heat-exchanger fin as a function of ice formation, is inexpensive and can be easily mounted on existing refrigeration units. This same sensor can be used to monitor the level of dirt formation on the fins and be used in a preventative maintenance program for scheduling cleanings when necessary. The system's controller uses signals from the sensor to initiate and terminate the defrost cycle as well as to control the temperature in the refrigerated zone.
The projected unit cost is about the same as that of the timer and thermostatic controller being replaced; however the new system could save up to 15% of the power used by the refrigeration unit.  | |
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| Benefits
- About 4% of all power consumption in the United States is used in refrigeration. An effective demand-based defrost system will result in a reduction of refrigeration power use by 7% to 15%.
- Improved temperature control minimizes the duration and frequency of defrost cycles, reducing the occurrence of damaging freeze-thaw cycles and saving energy.
- The control algorithms are capable of providing an alarm to indicate failure of components, such as a fan or control solenoid.
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| Applications
- The simplest application is for small refrigeration units, such as those in convenience stores, which use a compressor and a single cooling coil. The inexpensive controller can directly initiate and terminate the defrost cycles for these units.
- Refrigeration systems for industrial plants (chemical, food processing, concrete, etc.) and supermarkets have multiple evaporative coils that are supplied with refrigerant from compressors that may not be near the units. For these systems, multiple controllers can be used in concert to perform the defrost cycles for all of the evaporative coils without the risk of defrosting multiple cases simultaneously.
- The system and/or patented frost sensor will be integrated into the control networks of large industrial plants.
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| If you'd like to download a copy of the ADA Techbrief * on this topic, please click here,
or for more information, email Pat French
* ADA TechBriefs are available in PDF format.
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