Plant Services - September 2007 - (Page 51) EfficiEncy HVAC heat exchangers on screw compressor packages. The heat available from oil cooling heat exchangers is available in reasonable quantities and at a higher temperature when compared to the heat available for recovery from the discharge gas stream. 7. Compressor sequencing and control that poor hot-gas defrost sequences rather than defrosting on the basis of and controls accounted for 13% of a time-clock. the electrical energy consumption in a cold storage warehouse. Establish 9. Convert from liquid-injected a defrost sequence that avoids hot oil cooling to external cooling gas dwell times in excess of 15 minScrew compressors require some means utes duration and defrost individual of oil cooling. Using high-pressure liqevaporatorsServices ad for 07.qxp 4/26/2007 10:55 oil cooling is 1 uid refrigerant for AM Page common Plant only on an as-needed basis Controls are required to match compressor capacity to system demand. The most widely used compressor technology in industrial refrigeration systems is the screw compressor. Unfortunately, screw compressor efficiency decreases Establish a defrost sequence that avoids hot gas dwell times in excess of 15 minutes duration. as it unloads in response to decreasing demand. For example, a typical screw compressor operating at -20°F suction and 90°F condensing will have a fullload efficiency of about 2.2 BHP/ton. When unloaded to its minimum capacity (10% in this case), the horsepower per ton requirement increases to about 8.8 BHP/ton. Review your sequence of operation and minimize the time intervals at which individual machines operate at part-load ratios less than 70%. With Summit Ultima there are no puzzles to solve when it comes to choosing the best lubricant for your air compressor. When it comes to oil compatibility, oxidation resistance, and extended drain intervals, Summit Ultima removes all guesswork. Summit Ultima is compatible with virtually all OEM lubricants on the market today. Additionally, Summit Ultima will continue to provide superior service, protecting your compressor when other lubricants will start to sludge and produce varnish, even in the harshest of conditions. 8. Improve defrost sequences Air-cooling evaporators that operate at low temperatures will accumulate frost. As the coil ices up, its capacity decreases, which decreases system efficiency. Manske (2000) estimated Contact a Summit dealer today 800.749.5823 References: Manske, K., “Performance Optimization of Industrial Refrigeration Systems,” M.S. Thesis, University of Wisconsin-Madison, (2000). Reindl, D.T., et. al., Industrial Refrigeration Energy Efficiency Guidebook, Industrial Refrigeration Consortium, www.irc.wisc.edu/?/or der (2004). September 2007 ISO 9001:2000 Registered P.O. Box 131359 • Tyler, TX 75713 • 800.749.5823 • www.klsummit.com www.PLANTSERVICES.com 51 http://www.klsummit.com http://www.klsummit.com http://www.irc.wisc.edu/?/order http://www.irc.wisc.edu/?/order http://www.PLANTSERVICES.com
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