Abstract
We developed a packaged air-conditioner that improves annual efficiency. The developed system has a highly efficient wide-range compressor that improves the heat pump efficiency in the low air-conditioning loads, a heat exchanger that is optimized for both a vapor compression refrigeration system and refrigerant natural circulation system, an adaptive controller that suppresses unnecessary start-and-stop compressor operation and a refrigerant natural circulation system that enables highly efficient operation under a low ambient temperature condition. For this developed packaged air-conditioner, we tested and proved that <br>(i) the annual efficiency of the system was 1.51 times compared with that of the conventional one in a thermostatic chamber, <br>(ii) the efficiency for actual use was 1.58 times for the collaboratory of Hokkaido University in Sapporo and 1.67 times for the CAE room of Hitachi Appliances, Inc. in Shizuoka at ambient temperature in 2012, and <br>(iii) by revising the data the efficiency for actual use was 1.55 times for a common office in Tokyo at normal ambient temperature.
