閉鎖型苗生産システムに設置した家庭用エアコンの冷房時成績係数

Abstract

Electric energy consumption for cooling (Wc) and the coefficient of performance for cooling (C) were investigated in a closed-type transplant production system (CTPS). C is defined as the ratio of heat energy absorbed by the evaporator of the air conditioner to Wc. A Basic Module Room with thermally insulated walls (5.8 m (W), 2.7 m (L), 5.4 m (H)) in the Research Unit for Closed Plant Production Systems at Chiba University was considered as a model CTPS. Home-use air conditioners, fluorescent lamps, fans and humidifier were installed in the CTPS. One hundred fifty-one data sets were collected for the analysis during the period from 1 May 2000 to 30 April 2001 when air temperatures inside the CTPS (Tin) during photo-and dark period were 29-31°C and 27-29°C, respectively. The chemical energy assimilated by the transplants was considered to be negligible. In the preliminary study, the number of air exchanges of the system was found to be 0h-1 Heat energy transmission through the walls was estimated as the product of heat transmission coefficient (ceiling and side walls : 0.3 W m-2 k-1 floor : 0.2 W m-2 K-1) and the air temperature difference between inside and outside the CTPS. Subsequently, C was estimated by dividing the heat energy generated inside the CTPS (Q) by Wc. Wc increased with increasing air temperature outside the CTPS (Tout) and with increasing Q. Most (72-86%) of the electric energy was consumed by lamps. The rest was consumed by air conditioners (7-17%) and other equipments (5-15%). The average value of C was 7.6 under this experiment condition. The estimated values of C were 1.1-2.6 times greater in this experiment condition than the catalog value measured in the standard condition (Tin : 27°C, Tout : 35°C), because Tout was lower than Tin. C increased with decreasing Tout and with increasing Q. These results show that C of a recent model of home-use air conditioner is relatively high, and its application is beneficial for reducing Wc in the CTPS.