22 May 2008

ENERGY EFFICIENCY OF ROOM AIR CONDITIONER UNDER VARIOUS OUTDOOR CONDITIONS AND OPERATING MODES


Energy efficiency of room air conditioner for residential house depends much on
compressor frequency, the ambient temperature and humidity of the external unit, operation
mode and so on. Heating and cooling loads of a house are widely distributed in Japan
because occupants normally stop heating or cooling during their absence, and thereby the
room air conditioner often operates with low compressor frequency. Efficiency for varying
partial load of an air conditioner is hence essential to calculate seasonal energy consumption
for heating and cooling. In this paper, we tested a room air conditioner in the experimental
house built in an artificial climate chamber and measured the steady-state efficiency in
various conditions such as heating/cooling load, outdoor and indoor temperature and
humidity and the operating mode. The results clarified that the efficiency and sensible and
latent heating/cooling capacity of the tested room air conditioner depended on the conditions
and the operating mode, and also clarified that the efficiency especially dropped in
intermittent on-off operation and defrosting operation.