Online ISSN : 1881-2058
Print ISSN : 0037-105X
ISSN-L : 0037-105X
Volume 65 , Issue 5
Showing 1-18 articles out of 18 articles from the selected issue
Lectures at IIS Open Campus
Research Flash
  • Rongling LI, Ryozo OOKA, Masanori SHUKUYA
    2013 Volume 65 Issue 5 Pages 699-703
    Published: September 01, 2013
    Released: February 07, 2014
    When evaluating the efficiency of heat pump systems, the most commonly used measure is the energy (or the first law) efficiency, which is modified to a coefficient of performance (COP) for heat pump systems. However, for indicating the possibilities of thermodynamic improvement, exergy analysis (or second law analysis) is needed. This study presents a procedure for exergy analysis of heat pump systems using energy, entropy and exergy balance equations. The proposed method is used to compare a ground-source heat pump system and an air-source heat pump system. Exergy efficiency values for both systems are calculated, and thereby exergy consumption in each of the system components are clarified to demonstrate the potential for improvements.
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  • Rongling LI, Ryozo OOKA , Bjarne W. OLESEN
    2013 Volume 65 Issue 5 Pages 705-708
    Published: September 01, 2013
    Released: February 07, 2014
    This paper presents the results of a field study of the performance of a water-based radiant ceiling system in relation to its heating capacity and thermal comfort in a room. Based on the theoretical equations for the heat flux between ceiling systems and the resistance model recommended in ISO 11855-2 and EN 14240, measurements were implemented when the room was in the heating mode. The heat flow between the ceiling panels and the room was also calculated based on the theoretical model in ISO 11855-2. The result of this calculation was compared with the experimental data to verify the accuracy of the measurements. The comparison shows good agreement between the theoretical heat flow and the measured data. Based on the experimental data, the upward heat transfer coefficients were also calculated. The thermal comfort measurement showed that the air and operative temperature distributions in the room were highly uniform.
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