드라이쿨러를 적용한 프리쿨링 시스템의 특성 및 에너지 절감 연구

Abstract

Recently, the buildings requiring air-conditiong in winter season have increased. Using low temperature of out-door, Free cooling system is used to reduce energy consumption of cooling. Because free cooling system is able to prevent pollutant inflow and control temperature stably, this system mainly is used in a data center and industrial process. These days, some official buildings use this system due to cooling load in winter season. Many case of free cooling system adopt cooling tower to cool chilled water and condensation heat of refrigerator, but cooling tower has some shortcomings such as freeze and burst, difficult maintenance so on. To solve such problems, free cooling system using dry-cooler was proposed and performance characteristic and national adaptability of south Korea were analyzed in this study. The main results were summarized as follows. Dry-cooler capacity is influenced by out-door temperature, required chilled water temperature and LMTD(Logarithmic Mean Temperature Difference) of dry-cooler. As out-door temperature is more low, dry-cooler capacity become increased. in addition, as required chilled water temperature is more high and LMTD is more low, the out air temperature range is widened for using dry-cooler. If out-door temperature is below 0℃, antifreeze need to be used because freeze and burst can be occurred. In case of South Korea, antifreeze of 34% of ethylene glycol concentration is proper. For selection of compatible working fliud, compressor load of R22, R134a, R407C, R404 and R410C is compared. Considering environmental regulation and energy consumption, R134a is best working fluid. When comparing compressor load of existing refrigeration system and free cooling system, the region where energy saving effect is greatest is Chuncheon. Energy reduction amount of Seoul is 11%, Chuncheon is 17.5%, Deajeon is 15%, Ulsan is 14%. In case of large scale of air-conditioning, it is reasonable to use free cooling system although the system is used in Seoul.