Study On Reduction In Electric-energy Consumption For Cooling By Cooperating Air Conditioner With Air Exchanger In Plant Factory With Artiifcial Light

Plant factory (PF) with artificial light has incomparable advantages compared with traditionalagriculture, such as saving space and resource, improving qualities, etc. However, the popularizationand application of the PF is limited by operation cost now. In addition, the cost of electric-energyconsumption accounts for large proportion of the operation cost. Electric-energy consumption for airconditioner used as cooling equipment in the plant factory (PF) accounted for15%~35%of the totalelectric-energy consumption. In order to decrease electric-energy consumption, in this experiment, theair exchanger (AE) cooperated with air conditioner (AC) was used for cooling, AC with high power wasreplaced by AE with low power to decrease the runtime of AC, which aims at cutting downelectric-energy consumption for cooling and run cost. The results showed that:(1) Effects on operation performance of cooling equipments with outside air temperature are asfollows. When inside air temperature was set as20℃with the outside air temperature ranged from-2to10℃, the COP of air conditioner changed from7to10；when inside air temperature was set as25℃with the outside air temperature ranged from-2to5℃, the COP of air conditioner changed from7to9；When inside air temperature was set as20℃with the outside air temperature ranged from-2to10℃,the electric-energy use efficiency of air exchanger (Uf) changed from6to14. When inside airtemperature was set as25℃with the outside air temperature ranged from-1to4℃, the electric-energyuse efficiency of air exchanger (Uf) changed from11to16. Compared COP of the AC with Ufof AEunder the same condition, the lower the outside air temperature was, the higher the latter was. In otherwords, the energy-saving effect would be higher with the decrease of the outside air temperature.(2) The electric-energy consumption in the PF with AE was reduced by24.6%~63.0%and2.3%~33.6%when outside air temperature ranged from-4°C to8°C, and the runtime of air conditionerwas reduced by36.6%~82.0%and16.3%~64.2%when outside air temperature ranged from-4°C to6°C, during photoperiod and dark period, respectively, compared with the electric-energy consumptionin the PF only with AC, and the reduction rate of electric consumption and the runtime of airconditioner increased with the decrease of outside air temperature.(3) Although the AE cooperated with AC for cooling could bring energy-saving effect, it alsoeffected temperature, humidity and CO2concentration. Inside air temperature the two PFs weremaintained at25°C and15°C during photoperiod and dark period, respectively. VPD has the samevariation tendency with the inside air temperature, and the VPD in the experimental PF is higher thanthat in the comparison PF. Hence, transpiration was increased in the experimental PF. The CO2concentration ranged from380μmol/mol to450μmol/mol in the both PFs, CO2concentration in theexperimental PF was higher than that in the comparison PF during photoperiod, this method introducingoutside air with low temperature for cooling replenished the CO2concentration during photoperiod.