Root-zone Cooling Evaluation Using Heat Pump for Greenhouse Strawberry Production
Root-zone Cooling Evaluation Using Heat Pump for Greenhouse Strawberry Production
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DOI：
10.21273/horttech04007-18
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发表时间：
2018-10
期刊：
影响因子：
1
通讯作者：
S. Moritani;H. Nanjo;Atsushi Itou;Teruki Imai
中科院分区：
文献类型：
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作者：
S. Moritani;H. Nanjo;Atsushi Itou;Teruki Imai
地源热泵（GSHP）已被用来冷却水，以促进夏季在容器中种植的“Natsuakari”草莓（Fragaria ×ananassa）的冷却。已经考虑了两种类型的土壤容器和冷却系统。在一个系统中，冷水管放置在土壤下方和土壤顶部，而另一种冷却系统则使用冷水穿过放置在土壤下方和灌溉渠道内的管道，以方便底部灌溉。通过观察温室空气和土壤之间的温度关系来评估每个系统的冷却效率。该关系用椭圆曲线表示，椭圆曲线的几何中心和倾斜角分别表示代表性的日土壤温度和温度稳定程度。在本研究中考虑的两个植物生长期，底部灌溉系统的两个值都较低，从而表明可以通过更大的热对流来维持较冷和相对恒定的土壤温度。这种更大的冷却方法是通过将冷水通过底部灌溉通道快速转移到根部区域来促进的，这是由于植物蒸腾作用以及从土壤到冷却管的热传导引起的土壤含水量减少所致。当管道显着冷却时，所测得的埋地管系统土壤温度最低 (9.4 °C)。尽管所考虑的底部浇水系统的设置相当敏感，因为该系统需要维持整个容器的恒定水位，但与不使用地源热泵的情况相比，这两个系统都有效地产生了较低的土壤温度。
Ground-source heat pumps (GSHPs) have been used to chill water to facilitate cooling of ‘Natsuakari’ strawberry (Fragaria ×ananassa) grown within containers during the summer. Two types of soil containers and cooling systems have been considered. In one system, cold-water tubes were placed under as well as over the top of the soil, whereas the other cooling system used cold water passing through tubes placed under the soil and within the irrigation channel to facilitate bottom irrigation. The cooling efficiency of each system was evaluated by observing temperature relationships between greenhouse air and soil. The relationship was represented by means of an elliptic curve, the geometric center and tilt angle of which indicated representative daily soil temperatures and degree of temperature stability, respectively. Both values were observed to be lower for the bottom irrigation system during the two plant growth periods considered in this study, thereby indicating that colder and relatively constant soil temperatures can be maintained via greater heat convection. This greater cooling method was facilitated by rapid transfer of cold water through the bottom irrigation channel into the root zone, resulting from reduction in soil moisture content induced by plant transpiration in addition to heat conduction from the soil to the cooling tube. Measured soil temperatures for the buried-tube system were observed to be coldest when the tube was chilled considerably (9.4 °C). Although the setup of the considered bottom watering system was rather sensitive in that the system required maintenance of a constant water level throughout the container, both systems effectively produced cooler soil temperatures compared with the case in which no GSHP was used.