복합열원 난방시스템의 성능특성에 관한 연구

Abstract

This study conducted to analyze operating characteristics of a heat pump system which supplies heat to conditioned space with solar and air as heat sources. The solar energy is unlimited and clean, however, the density of the solar is relatively low and strongly affected by climate conditions. To solve problems in solar assisted heat pump system, hybrid heat pump system was developed and field test was conducted to analyze the system performance and to improve system reliability. The developed system uses R-22 as working fluid that prevents outbreak by winter-sowing from freezing of working fluid at temperature under freezing point. The developed system has three types of operating mode. First one is a hybrid heat source heat pump system(TypeⅠ) which is basic model of this study. Second one is the same system with anti-superheat technology(TypeⅡ) and third one is the system with anti-freezing technology(TypeⅢ) of the basic model. Alternation of solar heat or air heat is controlled by pressure regulator which is inserted to inside of solar collector. If the inside pressure of solar collector is higher than setting pressure, heat absorbed from solar collector and supplied to the heat pump as heat source. However, if the inside pressure of solar collector is lower than setting pressure, air is selected as heat source of the heat pump system. In winter season, rapid conversion of the heat source(air to solar or solar to air) is occurred which is depended on intensity of the solar. In summer, the environment air temperature of the collector effects on the conversion rate of the heat source. Even though the solar intensity is low, the inside temperature of the solar collector is still high due to the environment temperature of the collector that make the pressure of the solar collector still high enough to runs solar collector as heat source. At this state, air is selected as heat source because of the air temperature is high enough to supply heat to the heat pump system rather than the solar heat. The COP of the system in winter season is higher than summer's due to the alternation of the two heat source. The system COP using the solar as heat source is higher than air source, because the temperature of solar collector is much higher due to solar radiation and environment temperature. As results, developed system solves one of the problems in solar system which caused a winter-sowing.