응축과 가열 방식을 적용한 백연저감 냉각탑에 관한 연구

Abstract

냉각탑은 냉동공조, 발전소, 제철소, 정유소 등 많은 산업 분야에 널리 쓰이고 있다. 인구밀도가 높아지고 거주지역과 산업 지역의 경계가 불분명해지면서 건물 옥상 등에 설치된 공조용 냉각탑에서 발생하는 백연과 소음이 주변 거주자에게 피해요인으로 거론되고 있다. 겨울철 특히 가시화되는 백연은 주민들에게 공해로 인식되기 때문에 냉각탑 업계에서는 백연의 시각적 현상을 최소화가 필요한 실정이다. 그러나 겨울철 영하권 온도에서 백연저감 성능이 있다고 알려진 냉각탑은 건구온도 –2℃이하부터 백연은 여전히 생성되는 경우가 많다. 따라서 성능이 향상된 새로운 백연저감 방식이 필요하다. 공장 제작형 냉각탑 중 보편적으로 사용되고 있는 직렬 히팅 방식의 백연저감 시스템에 응축 시스템을 추가하여 백연 성능을 높일 수 있는 방안에 대해 연구하였다. 외부 공기를 냉각탑 중앙까지 흡입시키고 믹싱 효율이 좋은 V자형 에어 믹서와 열성능 향상을 위해 외부 공기 인입 차단이 가능한 슬라이딩 댐퍼를 개발하였다. 또한 공기 중 응축된 물방울들을 여과하여 냉각수로 환원시킬 수 있는 일리미네이터를 개선하여 적용하였다. 위 개발한 대퍼와 개선한 일리미네이터를 직렬 히팅 방식의 백연저감 냉각탑에 적용하고 열 성능과 백연 성능 테스트를 진행하였다. 테스트 결과, 기존에 백연저감이 어려웠던 외기온도 –5℃에서도 백연저감을 확인하였다. 또한 무게와 부피의 큰 증가 없이 백연저감 성능 증가시켜 이는 건물 옥상 등에 설치되는 공조용 냉각탑에 적용 가능한 시스템임을 확인하였다.

Cooling towers started with the condensers of steam engines since the 19th century and are now widely used in industries such as refrigeration, air conditioning, power plants, steel mills, and refineries. As the population density increases and the boundaries between residential and industrial areas become unclear, white smoke, the plume, from the cooling towers are hurting neighboring residents. The plume in winter is the health and local financial challenges for the cooling tower industry since the visibility of smoke increases residents anxiety over the possible pollution and local real estate value reduction. In addition, lack of cooling towers with sufficient plume reduction performance that falls to the subzero temperatures in winter signifies the challenge. Since the plume is often produced when the dry bulb temperature below –2℃, improvement of a cooling tower performance in white smoke reduction is critical to meet customers needs. Therefore, this study was developed and modified the form of an existing plume abatement method to develope the plume reduction method of a cooling tower. In order to reduce the plume effectively, the plume abatement performance was maximized by applying heating of air after the condensation as similar to a household air dehumidifiers. This study examined the refrigeration cycle and the plume abatement system of a cooling tower when the refrigerant and compressor of the dehumidifier were used. The maintenance, manufacturing, and installation of the cooling tower consequently failed to meet financial feasibility and reasonable size increment. Since heating coil types of plume abatement system are the determining factors of increasing the performance of a plume abatement, therefore, this study developed and conducted a performance test of heating air after the condensation with different types of the former heating coils. The V-shaped air mixer determined that high efficiency of inducing inhalation of outside air to the center of the cooling tower within a short section. Also, the developed sliding damper in this study was able to prevent an inflow of the outside air that maximizes the thermal performance during the summer. This study developed an eliminator to filter the condensed water droplets from the air and send back the water droplets into the cooling tower as a coolant. The V-shaped air mixer, sliding damper, and the eliminator were applied to the plume abatement cooling tower and a performance test was conducted with the dehumidifier heating method. As a result, the cooling tower demonstrated a high plume abatement performance even at –5℃ which was the main drawback of the former existing conventional plume abatement cooling tower system.