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Near-optimal control of variable speed drives on evaporative condenser fans.

Number: 0811

Author(s) : JEKEL T., CLAAS M.

Summary

Variable frequency drives (VFDs) are increasingly being specified on evaporative condenser fans for industrial refrigeration systems using anhydrous ammonia. Historically, fan control strategy has emphasized operation at the lowest refrigeration system condensing pressure with an expectation that system efficiency will be maximized. More recently an “approach to wet-bulb” strategy that reduces the condenser fan speed and allows the refrigeration system to operate at slightly higher condensing pressures in order to counterbalance significant condenser fan energy on those systems with larger heat rejection capacities; thereby, improving the overall refrigeration system efficiency. Because the approach to wet bulb control strategy requires the use of sensors to monitor the ambient wet bulb temperature and added control complexity, it prompts the question as to whether the energy benefit associated with reduced condenser fan speeds can be accomplished in a simpler way. This paper introduces a simplified, near-optimal control strategy for evaporative condenser fans fitted with VFDs. The strategy sets a target nominal condenser fan speed and only varies the fan speed when the condensing pressure falls below an operating limit minimum or above an operating limit maximum. In this paper, we show this simplified condenser fan control strategy achieves, substantially, the same benefits as an “approach to wet-bulb” without requiring the installation and ongoing maintenance associated with sophisticated wet bulb monitoring sensors.

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Pages: 10

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Details

  • Original title: Near-optimal control of variable speed drives on evaporative condenser fans.
  • Record ID : 30031841
  • Languages: English
  • Subject: Technology
  • Source: Proceedings of the 26th IIR International Congress of Refrigeration: Paris , France, August 21-25, 2023.
  • Publication date: 2023/08/21
  • DOI: http://dx.doi.org/10.18462/iir.icr.2023.0811

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