Reduction in Electric-energy Consumption for Cooling by Introducing Outside Cold Air in a Plant Factory

doi:10.3969/j.issn.1000-6362.2015.03.006

Abstract

Abstract: The commercial use of the plant factory (PF) with artificial light is limited because of its high operation cost. Thus, in order to reduce electric-energy consumption for cooling and the operation cost, two PFs were used in this study, in the experimental PF, a coupling control method by introducing outside cold air with fan together with air conditioner (AC) was employed for cooling, while in the control PF, only AC was used. Null CO2 concentration difference method to maintain inside CO2 concentration at the same level as that of atmosphere was used in both PFs. The effects of introducing outside cold air on the air temperature, vapor pressure deficit (VPD), CO2 concentration, electric-energy consumption, coefficient of performance (COP) of AC and fan, yield and content of photosynthetic pigments of lettuce were investigated. The results showed that: (1) inside air temperature could be maintained at the suitable range (light period:23-27℃, dark period:18-22℃) for lettuce growth by introducing outside cold air. VPD in the experimental PF (light period:1.3-2.7kPa, dark period:1.2-1.9kPa) was higher than that in the control PF (light period:0.3～1.3kPa, dark period:0.3-0.5kPa). Null CO2 concentration difference method could maintain the inside CO2 concentration as the same level as that of atmosphere. (2) The total electric-energy consumption was around 10.8% lower in the experimental PF than that in the control PF. (3) When the outside air temperature ranged from -4 to 5℃, the sensible heat factor ranged from 0.4 to 0.9, COP of the fan of 19.3-28.9 was higher than that of the ACs (5.3-14.7 in the experimental PF; 5.8-14.9 in the control PF). (4) There were no significant differences on the yield and content of photosynthetic pigments of lettuce in two PFs. The results indicate that PF cooling by introducing outside cold air can be considered as an efficient method for reducing its electric-energy consumption.

Key words: Air conditioner, Coefficient of Performance, Temperature, CO2 concentration, Energy saving

XIN Min，TONG Yuxin，YANG Qichang，WEI Lingling，WANG Jun，BIAN Zhonghua. Reduction in Electric-energy Consumption for Cooling by Introducing Outside Cold Air in a Plant Factory[J]. Chinese Journal of Agrometeorology, 2015, 36(03): 287-295.

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