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2016 Vol.25, Issue 4 Preview Page
Analysis of Heat Transfer Characteristics in Response to Water Flow Rate and Temperature in Greenhouses with Water Curtain System

수막하우스의 유량 및 수온에 따른 열전달 특성 분석

Hyung-Kweon Kim1*
,
Seoung-Hee Kim1
,
Jin-Kyeong Kwon1
김 형권1*
,
김 승희1
,
권 진경1
1Protected Horticulture Research Institute, National Institute of Horticultural and Herbal Science, RDA, Haman 52504, Korea
1국립원예특작과학원 시설원예연구소
*Corresponding author: khgweon@korea.kr
30 November 2016. pp. 270-276
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Abstract

This study analysed overall heat transfer coefficient, heat transmission, and rate of indoor air heating provided by water curtain in order to determine the heat transfer characteristic of double-layered greenhouse equipped with a water curtain system. The air temperatures between the inner and outer layers were determined by the water flow rate and inlet water temperature. Higher water flow rate and inlet water temperature resulted in the increased overall heat transfer coefficient between indoor greenhouse air and water curtain. However, it was found that with higher levels of water flow rate and inlet water temperature, indoor overall heat transfer coefficient was converged about 10W·m-2·°C-1. The low correlation of overall heat transfer coefficient between water curtain and air within double layers was likely because the combination of greenhouse shape, wind speed and outdoor air temperature as well as water curtain affected the heat transfer characteristics. As water flow rate and inlet water temperature increased, the heat transferred into the greenhouse by water curtain also tend to rise. However it was demonstrated that the rate of heat transmission from water curtain into greenhouse with water curtain system using underground water was accounted for 22% to 28% for total heat lost by water curtain. The results of this study which quantify heat transfer coefficient and net heat transfer from water curtain may be a good reference for economical design of water curtain system.

Keywords
energy balance
heat insulating effect
heat transmission
heating effect
underground water

단동 이중비닐하우스에서 수막에 의한 열전달 특성 및 가온효과를 구명하기 위하여 작물이 재배되는 수막온실 의 실내외 기온과 수막의 수온 등을 계측하였고, 단위 피복면적당 수막에 의한 총 공급열량, 열관류율, 관류열 량, 온실 내부로 전달되는 열량비율 변화를 비교·분석하 였다. 1중과 2중사이의 기온은 외부기온보다는 수막유량 과 공급수온에 따라 결정되는 것으로 나타났다. 수막유 량이 증가할수록, 공급수온이 높을수록 수막과 2중 하우 스 내부와의 열관류율(UW-IN)은 유의하게 증가하는 경향 을 보였다. 그러나 수막유량과 공급수온이 일정조건(수 막유량 0.00266L·m-2·s-1, 공급수온 19.8°C) 이상에서는 UW-IN 값이 10W·m-2·°C-1 정도로 수렴되는 것으로 나타 났다. 수막과 1·2중 공기 사이의 열관류율(UW-B)의 경우 에도 수막유량 및 공급수온에 따라 증가하는 경향을 보 였으나, 경향성은 상대적으로 작은 것으로 분석되었다. UW-B는 연구자에 따라 전체적으로 큰 차이를 보이고 있 으며, 본 연구에서는 3.27~4.44W·m-2·°C-1의 범위를 보였 다. 수막에 의한 총 공급열량(QW)과 온실 내외부로 전달 되는 관류열량(QW-IN, QW-B)의 경우, QW 값이 QW-IN과 QW-B의 합과 매우 유사하게 일치하고 있어 본 연구에서 제시한 결과가 신뢰성이 있음을 확인할 수 있었다. 수막 에 의해 내부공기를 가열하는데 사용되는 열량은 최대 57% 수준으로 분석되었고, 우리나라 수막재배온실의 경 우 약 22~28% 수준으로 판단된다. 본 연구는 농업인이 실제 사용하는 수막온실과 가장 유사한 조건에서 수막에 의한 온도변화, 열관류율과 관류열량을 계량화함으로써 향후 경제적인 수막온실 설계 시 활용할 수 있을 것으 로 기대된다.

키워드
가온효과
관류열량
보온효과
열평형
지 하수
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Information
  • Publisher :The Korean Society for Bio-Environment Control
  • Publisher(Ko) :(사)한국생물환경조절학회
  • Journal Title :Protected Horticulture and Plant Factory
  • Journal Title(Ko) :시설원예ㆍ식물공장
  • Volume : 25
  • No :4
  • Pages :270-276
  • Received Date : 2016-09-28
  • Revised Date : 2016-11-09
  • Accepted Date : 2016-11-11
  • DOI :https://doi.org/10.12791/KSBEC.2016.25.4.270
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