摘要:为掌握水培营养液的热传导变化规律，探讨叶菜生产系统营养液作为贮热介质的蓄热保温性能，在山西农业大学设施农业工程研究所叶菜生产系统中使用SH-16路温度巡检仪，测定多孔定植板条件下系统内不同深度（0 cm、5 cm、10 cm、15 cm）营养液的温度变化。试验结果表明：不同深度营养液温度变化显著不同，表层变幅最大，越往深层变幅越小；秋季营养液各深度最高温分别出现在14：00、16：00、17：40、20：00，并随着营养液深度的增加而快速降低。根据各深度日较差的变化幅度，将营养液划分为热交换层（>3℃）、热缓冲层（1~3℃）和热稳定层（0~1℃），分别位于液面表层0~5 cm、5~10 cm和10~15 cm。叶菜生产系统营养液深度为21.5 cm时，不同层次日较差变化符合对数关系：y=-2.619lnx+4.215 2，即液面以下20 cm处日较差为0℃。上述结果表明能量在营养液中是逐层进行传导的。
关键词:营养液/
叶菜生产系统/
贮热介质/
热传导/
能量
Abstract:In order to grasp the characteristics of heat transfer of hydroponic nutrient solution as heat storage medium and the related heat storage and preservation performance, nutrient solutions of leaf vegetable production systems were used for experimentation. The experiment was conducted at the solar greenhouse of Agricultural Engineering Institute of Shanxi Agricultural University. In this study, SH-16 road temperature inspection was used in leaf vegetable production systems and sensor elements placed at several different depths of different positions to monitor solution temperature. The regulation of temperature change of nutrient solutions in the system under porous planting plates were discussed. The experimental results showed that temperature change in nutrient solution at different depths were significantly different. The largest amplitude of temperature variation of nutrition solutions was at surface layer. The deeper the nutrient solution, the smaller was the variation. The highest temperature of nutrient solution in autumn decreased rapidly with increasing nutrient solution depth, and happened at 14:00, 16:00, 17:40 and 20:00 for the solution depths of 0 cm, 5 cm, 10 cm and 15 cm respectively. Based on the daily range of temperature at different depths, nutrient solutions were divided into three temperature layers-heat exchange layer (daily range of temperature > 3℃), heat buffer layer (daily range of temperature of 1-3℃) and heat stability layer (daily range of temperature at 0-1℃), which were located in the solution layers of 0-5 cm, 5-10 cm and 10-15 cm, respectively. When the nutrient solution depth of leaf vegetable production system was 21.5 cm, the relationship between daily temperature difference and solution depth (0 cm, 5 cm, 10 cm, 15 cm were expressed as 1, 2, 3 and 4 in the function) was described with the logarithmic function y=-2.619lnx + 4.215 2. That indicated that daily temperature difference at 20 cm below solution surface was 0℃. The above results indicated that energy was conducted on a layer-by-layer basis in the nutrient solution of hydroponic system.
Key words:Nutrient solution/
Leaf vegetable production system/
Heat storage medium/
Heat conduction/
Energy
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