시설내 온도분포 균일화를 위한 온풍난방기용 2중 덕트개발

Air temperature variation along the length of the air duct in an air-heated plastic greenhouse was large, 13~15°C between the front and the rear side of a greenhouse. To reduce this temperature variation, a new PE-film air duct having a small duct inside a large duct (double duct) was developed. This double duct was consisted of an inner duct with air outlets at a 0.15 m interval and an outer duct with air outlets at a 2.5 m interval. Diameters of the air outlet holes were 7, 15, and 35 ㎝ from the front to the end of the inner duct film, while identical 10 ㎝ holes were used on the outer duct film. As a result, air temperature was 46℃ at the beginning side and 47℃ at the ending side, while the conventional single duct had 53℃ at the beginning point and 38℃ at the ending point with a variation of 15℃ Height of a cucumber crop grown in a greenhouse with the new double air duct system was 65.5 ㎝, 14% increase as compared to that in a greenhouse with a conventional air duct system. Total fruit yield per 10a greenhouse in a greenhouse with the new double air duct system was 4,616 ㎏, which was 17% greater than that in a greenhouse with a conventional air duct system. Amount of heating oil consumption during March 3 to April 24, 2002 was 3,233 L per 10a greenhouse with the new double air duct system, which was 13% less than that with a conventional air duct system.