Appliance Design - May 2008 - (Page 33)

QUALITY & STANDARDS Equation Fig. 1. Ambient temperatures of St. Louis versus EER rating-point conditions. Table 3. Procedure for calculating the EER of a compressor. manufacturers use 20 DegF evaporating and 120 DegF condensing temperature. As a general rule, a compressor that has a higher EER at the rating condition could be expected to perform better in a system than one that has a lower EER. When EER is calculated using the AHRI standard, it is a useful method of comparing equipment and operating-condition choices, offering the benefit of standardization by utilizing one universal measure of compressor performance. It has become a helpful tool for both engineers and manufacturers and is currently a common method for calculation of refrigeration equipment energy efficiency. However, in any given location, the ambient temperatures vary greatly from the single condensing-temperature rating point used with the EER method. In fact, in some regions, temperawww.applianceDESIGN.com tures never even reach the ambient temperature corresponding to the EER rating-point condition. (See Figs. 1, 2, 3, 4, 5.) Therefore, EER does not give a complete representation of refrigeration system operation under other temperatures and conditions. Related to EER is another current efficiency measure, the Seasonal Energy Efficiency Ratio (SEER), which is specifically used to rate only air conditioning equipment. It expands upon Fig. 2. Ambient temperatures of Boston versus EER rating-point conthe EER analysis and is calculated ditions. over a range of expected external temperatures. SEER measures the BTU of cooling output during a typical cooling season divided by the total electric energy input in watt-hours (W-Hr) during the same period. The higher a SEER rating of a unit, the more energy efficient it is. Because SEER incorporates additional factors, such as seaapplianceDESIGN May 2008 33 http://www.appliancedesign.com

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Appliance Design - May 2008 Contents Editorial Shipments/Forecasts News Watch New and Notable Displays & Indicators Elastomers Quality & Standards Indoor Air Quality IHHS Highlights New Products Classifieds Design Marts Advertiser’s Index Association Report: PSMA

Appliance Design - May 2008

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