Study on efficiency improvement of packaged air conditioners for year round cooling with indirect outdoor air cooling (study on control methods of room air temperature and superheat)

Tsuneo Uekusa, Masahide Yanagi, Shinji Kimijima, Sunao Kawai

Research output: Contribution to journalArticle


The air conditioner which cools telecommunication equipment rooms or computer rooms must operate throughout the year. So we apply refrigerant pump cycle to the air conditioner to improve coefficient of performance (COP) at low outdoor air temperature. At first, this paper discusses two kinds of control methods. One is superheat control to manipulate refrigerant pump frequency. Refrigerant pump cycle controlled by this method can operate higher efficiency than that controlled by expansion valve. The other is room air temperature control method to manipulate air flow rate of condenser. Next, this paper discusses year round electric consumption comparison with conventional air conditioner. The electric consumption of the air conditioner with refrigerant pump is 50% shorter than that of conventional air conditioner.

Original languageEnglish
Pages (from-to)2097-2101
Number of pages5
JournalNihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B
Issue number660
Publication statusPublished - 2001 Aug 1



  • Air conditioner
  • Coefficient of performance
  • Control method
  • Indirect outdoor air cooling
  • Refrigerant pump
  • Year round cooling

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanical Engineering

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