Development of a variable speed compressor power model for single-stage packaged DX rooftop units

Yunhua Li, Mingsheng Liu, Josephine Lau

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Variable speed technology was applied to compressors for rooftop units (RTUs) and heat pumps in recent years. Compressor power is a critical parameter to evaluate system performance and conduct fault detection and diagnosis (FDD). However, existing power models often use numerous parameters related to the compressor geometrical dimensions and refrigerant physical properties which makes the existing models hard to implement in the field. In this paper, a semi-theoretical compressor power model was developed for single-stage RTUs equipped with a variable speed compressor and a variable speed indoor fan, based on the theoretical analysis and experimental studies. Under the normal conditions, the compressor power is correlated to the outside air temperature and compressor speed with a relative error of ±8%. This model can be employed in the field to develop a compressor power baseline for real-time FDD on the Direct Expansion (DX) RTUs.

Original languageEnglish (US)
Pages (from-to)110-117
Number of pages8
JournalApplied Thermal Engineering
StatePublished - Mar 5 2015


  • Fault detection and diagnosis
  • Power model
  • Rooftop units
  • Variable speed compressor

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Industrial and Manufacturing Engineering


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