Abstract
This paper describes field measurements conducted in several households with different heat demands for performance evaluation of residential combined heat and power (CHP) systems, which are increasingly becoming efficient domestic hot water supply systems using a storage tank. The annual dependence rates of electric power measured in the three households stood comparison with an average value of 205 households by the New Energy and Industrial Technology Development Organization (NEDO) and the New Energy Foundation (NEF). In particular, the rates between 14:00 to 15:00 in summer were high, and this system contributes to the reduction in the electric power consumption in grid-connected network areas. The AC electrical efficiencies at rated output operation were approximately equal to values obtained by NEDO and NEF. The decrease in the efficiency in the lower load factor was small, and high energy saving characteristics were confirmed. The annual primary energy reduction was 6.6, 21.1, and 5.4 GJ in each household. The tendency that a reduction effect improved when a large amount of exhaust heat was used was shown quantitatively. A comparison between the measured values and the calculated values using a CHP optimization tool was performed. The calculated annual primary energy reduction exceeded the measured values in each household, and a further performance enhancement in future should be possible.
