碩士 / 國立臺灣大學 / 生物產業機電工程學研究所 / 104 / Taiwan need to import lots of lettuce during the summer season due to the fact that lettuce prefer cool temperature (less than 23℃) to grow. It is also the reason that the plant factory with artificial lighting (PFAL) required lots of energy to remove the heat load. The focus of this study is to investigate on temperature of aerial and root zone environmentof semi-head lettuce (Boston or Butter head lettuce, Lactuca sativa L.). The hypothesis is that by applying chiller to reduce temperature (T) of nutrient solution allows lettuce to be grown at higher temperature, leading to lower energy cost. Two circulating systems include Ebb and Flood (E&F) and Deep Flow Technique (DFT) were investigated. Proper frequency when using E&F also under investigation. When the root zone can be controlled at 20℃, the upper limit of aerial T was found. Some evidence was found regards keeping root zone T stable is very important to get high yield. A modified plug tray was developed to improveyield.
At same root zone T, aerial T increase from 23 to 28℃enhanceplant growth leading to increase of fresh weight and reduce energy cost. There is no significant difference on fresh weight when aerial/root zone T are at 28/23 or 28/20. However, the 28/23 treatment reduced the energy consumption of chiller by 80% but increase energy consumption of AC, leading to a 20% reduction of totalenergy consumption in removing heat. If the COP of the chiller can be improved, the difference among two treatments can be minimized.
The suggested protocol to grow Boston lettuce is as follows: Ebb and Flood system, chiller and AC system with inverter should be used. The nutrient solution should be controlled at 23℃ using chiller, the UP and DOWN time of recirculating pump can be set at 7.5 minutes each, indoor CO2 concentration kept at 1200 ppm. The pH and EC are 6.0 and 1.2 mS.cm-1. LED is used at Seedling stage, the PPF is 150 with continuous light for 14 days. Tubular florescent lamps with color temperature of 6500 K are used for mature stage production after transplanting. The PPF is 200 and light period is 16 hours per day for 21 days. At DAS equals 35, the expected harvest fresh weight is around 105 g. The total electricity costs of circulating fans, pump, artificial light, AC and chiller for 21 days from transplanting to harvest is 0.122 NT$ per gram of produce. Assuming the efficiency of circulating fans, artificial lamps, COP of chiller and amount of production area can be increased, the energy cost drop to 0.048 NT$ per gram of produce.
| Identifer | oai:union.ndltd.org:TW/104NTU05415002 |
| Date | January 2016 |
| Creators | Shu-Wei Yang, 楊書瑋 |
| Contributors | Wei-Fang, 方煒 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 113 |
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