Estimating the Thermal Properties of the Cover and the Floor in a Plastic Greenhouse

Hyung-Kweon Kim, Young-Sun Ryou, Young-Hwa Kim, Tae-Seok Lee, Sung-Sik Oh and Yong-Hyeon Kim
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Hyung-Kweon Kim: Department of Agricultural Engineering, National Institute of Agricultural Sciences, RDA, Jeonju 54875, Korea
Young-Sun Ryou: Department of Agricultural Engineering, National Institute of Agricultural Sciences, RDA, Jeonju 54875, Korea
Young-Hwa Kim: Department of Agricultural Engineering, National Institute of Agricultural Sciences, RDA, Jeonju 54875, Korea
Tae-Seok Lee: Department of Agricultural Engineering, National Institute of Agricultural Sciences, RDA, Jeonju 54875, Korea
Sung-Sik Oh: Department of Agricultural Engineering, National Institute of Agricultural Sciences, RDA, Jeonju 54875, Korea
Yong-Hyeon Kim: Department of Bio-Industrial Machinery Engineering, Jeonbuk National University, Jeonju 54896, Korea

Energies, 2021, vol. 14, issue 7, 1-11

Abstract: This study comprehensively analyzed the heat loss and total heat transfer coefficient (U-value) of a single-span experimental plastic greenhouse covered with a double layer of 0.1 mm thick polyethylene. The air temperature and heat flux (W m −2 ) of the greenhouse components were measured from 18:00 to 06:00, and the energy balance equations under steady-state conditions were determined. The heat flux and U-value of the roof, sides, front and rear, and floor of the greenhouse were determined and compared. The results showed that these values for the roof play an important role in determining the heat load in the greenhouse, and that the average heat transfer through the floor is very small. The average U-value of the greenhouse cover is a comprehensive value which takes the U-values of the roof, sides, and front and rear into account through the use of an area–weighted average method. Finally, an average U-value of 3.69 W m −2 °C −1 was obtained through the analysis of the variations in the U-value, as it is related to the difference in air temperature between the interior and exterior of the greenhouse, as well as to the outdoor wind speed. The relationships between the average U-value and those of the roof, sides, and front and rear of the experimental greenhouse were modeled, and were shown to have a highly linear relationship.

Keywords: total heat transfer coefficient; plastic greenhouse; heat flux; area–weighted average; heat load (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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