養液循環泵與高低可調散熱型燈具於植物工廠內水耕栽培之研究

地球上溫室氣體、氣溫與海平面高度增加，使糧食生產岌岌可危，植物工廠利用環控系統提供植物最有利的生長環境，不受天候影響，可達穩定量產，被認為是解決糧食作物種植問題的可能辦法。植物工廠面臨到的主要問題為高成本，提升植物生長效率與減少耗能可以降低生產成本。植物工廠中的水培系統可分為循環系統和非循環系統，實驗測試各種商用循環泵浦的效果，包括離心式磁力驅動泵浦、再生自吸式泵浦和沉水式泵浦。此外，還研究了紫外線滅菌系統對營養液中離子濃度的影響，結果顯示循環泵浦對營養液中的離子濃度沒有顯著影響，然而，養液在通過紫外線滅菌系統處理48小時後，Fe3+離子的濃度顯著降低。此外，研究了三種循環泵浦對奶油萵苣 (Lactuca sativa var. capitata L.)生長的影響，泵浦循環期間的溫度記錄顯示，再生自吸式泵浦的養液溫度增加了15.5 °C，萵苣苗有明顯的枯黃葉燒及根部褐化的情形。養液中的離子濃度和萵苣的總鮮重在離心式磁力驅動泵浦和沉水泵浦之間沒有明顯的差異。使用離心式磁力驅動泵浦和再生自動加壓泵浦做為草莓 (Fragaria × ananassa Duch. cv. Toyonoka)水培系統的循環動力，泵浦循環期間的pH值皆穩定維持在6.2-7.0之間，在非循環系統中，溶液更新後的pH值降至5.5，2天後逐漸回升到6.5左右。非循環系統養液的離子濃度沒有明顯的變化，而循環系統利用養液中離子的濃度變化，計算出離子含量及消耗情形。草莓植株種植48天之後，無論是地上部或地下部的鮮重都是磁驅循環系統顯著高於非循環系統，兩種泵浦循環系統間的鮮重沒有顯著差異，兩種泵浦循環系統的地上部乾重顯著高於非循環系統，三種系統的地下部乾重沒有顯著差異。使用離心式磁力驅動泵浦循環系統栽培草莓苗，能得到比非循環系統更多的葉片及走莖數量，在地上部鮮乾重方面也有顯著的成長。使用致冷晶片套件來降低植物工廠中單層水盤的養液溫度，使用降溫後的養液搭配水冷散熱器降低層架內部溫度。在使用1-3台致冷套件時可以降低養液溫度範圍為4.94-9.36 oC，層架內部溫度降低3.34-5.52 oC。使用SolidWorks的Flow Simulation模組模擬層架內部的溫度分佈，並經由實驗印證。在第一代浮動燈板中，增加了多段開關與上置式風扇，燈板能配合植物生長調整高度，減少開燈數也能獲得一樣足夠的光強度，植栽區域的平均光合有效輻射PAR (photosynthetically active radiation)強度可達200 μmol m-2s-1以上，藉由上置式風扇可使植栽板溫度降低約2 oC。使用SolidWorks的Flow Simulation模組進行流場分析，設計出浮動燈板上的孔洞排列方式，搭配橫流扇組成通風型燈板，並以Arduino和超音波感測器控制馬達和滑輪，使燈板可以依照植物的高低自動升降。橫流扇及燈板上的孔洞製造出向上的氣流，帶走燈管發光時產生的熱，使植栽板上方溫度降低約3 oC。

關鍵字

植物工廠；水耕栽培；離子濃度；熱電致冷；計算流體力學

並列摘要

The increase of greenhouse gases, temperatures and sea level on the earth makes food production in jeopardy. The plant factories provide the most favorable growth environment for plants, which is unaffected by the weather and can reach stable mass production. It is considered as a possible solution to the problem of planting food crops. The main problem of plant factories is high cost, so increasing plants growth efficiency and reducing energy consumption can reduce production costs. Hydroponic systems in plant factories can be categorized into recirculating or noncirculating systems. In this study, the effects of various commercially available circulation pumps, including a centrifugal magnetic drive pump, a regenerative self-priming pump, and a submersible pump, were experimentally explored. In addition, the effects of an ultraviolet sterilization system on the ion concentrations in nutrient solutions were examined. For all three types of pumps, the results indicated that there was no significant effect on the concentrations of the nutrient solution. However, the concentration of Fe3+ ions decreased significantly after the nutrient solution was treated by a ultraviolet sterilization system for 48 hours. In addition, the effects of the three types of pumps on the growth of butterhead lettuce (Lactuca sativa var. capitata L.) were examined. The temperature records during the pump circulation tests showed that the nutrient solution temperature of the regenerative self-priming pump increased by 15.5 oC, which caused yellow seedling, scorching on the leaves, and browning of the roots. The ion concentration in the nutrient solutions and total fresh weight of butterhead lettuce did not show any noticeable difference between the centrifugal magnetic drive pump and the submersible pump. Using centrifugal magnetic drive pump and regenerative pressure controlled automatic booster as the cycle power of strawberry (Fragaria × ananassa Duch. cv. Toyonoka) hydroponic system. During the experiment of the pressured and magnetic drive circulating systems, the pH value remained constant within the range of 6.2–7.0. However, the pH value of the solution in the noncirculating system decreased to 5.5 in the first 2 days after the solution was changed, and gradually increased to approximately 6.5 over the following days. No significant change was noted in the ion concentration of the nutrient solution in the noncirculating system. The concentration of ions the nutrient solution recirculated by two types of pumps was measured, and the ion content and consumption in the solution was calculated. After the 48-day cultivation period, the aboveground and underground fresh weights of the strawberry plants in the magnetic drive recirculating system were significantly higher than those of plants in the noncirculating system, where no significant difference was observed between the two recirculating systems in this respect. Additionally, the aboveground dry mass of the strawberry plants in the two recirculating systems were significantly higher than that of the plants in the noncirculating system. However, the underground dry mass in the three systems did not exhibit any significant difference. The thermoelectric cooling kit was used to reduce the temperature of the nutrient solution in the single-layer tray in the plant factory. The cooled nutrient solution with a water cooling radiator was then used to lower the air temperature within the shelf. The use of one to three thermoelectric cooling kits reduces the temperature of the nutrient solution by approximately 4.94 to 9.36 °C, and reduces the air temperature within the shelf by 3.34 to 5.52 °C. SolidWorks Flow Simulation was used to effectively simulate the air temperature distribution within the shelf, and verified by experimental results. In the first generation of the light fixture board, multi-segment switches and overhead fans have been added. If the light fixture board can be adjusted the height along with the growth of the plant, the number of lights can be reduced to obtain the same enough brightness. The average photosynthetically active radiation (PAR) intensity of 200 μmol m-2s-1 was measured above the polystyrene board. The temperature above the polystyrene board reduced by 2 oC using the overhead fans. Using SolidWorks Flow Simulation to design the displacement of the round openings on the light fixture board, the upward airflow light fixture board was constructed with the cross-flow fans. An Arduino Uno with an ultrasonic sensor is used to control the motor and pulleys, and the light board can be automatically lifted in accordance with the height of plants. The upward airflow produced by the cross-flow fans and the openings on the light fixture board takes away the hot air that is generated by the glowing lamp. The temperature above the polystyrene board reduced by 3 oC.