周年高效、优质生产是日光温室的发展方向.针对日光温室夏季夜温过高、昼夜温差小且降温方法欠缺的问题,以设施园区地表水为冷源,以热泵作为能量提升、转换手段,对日光温室进行夜间降温,分析该方法的降温、除湿效果,对CO2浓度累积的影响及系统能耗、冷凝水回收量等,探讨水源热泵用于日光温室夏季夜间降温的环境调控能力及节能节水效果.结果表明,在夏季高温夜间(20:00-06:00),水源热泵系统可有效降低试验温室内气温,平均温度比自然通风的对照温室低2.6-2.9℃;同时,试验温室内气温低于室外气温,平均温差为1.6-1.7℃.试验温室内夜间平均相对湿度为74.3％-78.6％,比对照温室降低了8.9％-12.6％.在06:00时试验温室内CO2浓度可达1430-1660μL/L,约为对照温室的1.3-1.9倍,可在日出后一段时间内提升试验温室内作物的净光合速率.水源热泵系统运行稳定,日均制冷耗电量为19.3-19.9 W/m2,日均性能系数(coefficient of performance,COP)值可达4.1-4.4.系统制冷耗电量及COP受进风温度、含湿量的影响,均呈显著正相关关系(P<0.01).系统降温过程冷凝水回收量实测值为0.37-0.45 kg/(m2·d),可节约18％-21％的灌溉用水量.研究表明,水源热泵系统可有效用于日光温室夏季夜间降温、除湿,有助于CO2浓度累积,并具备良好的节能、节水效果.该研究为日光温室安全越夏生产提供了有效的环境调控方法.%Year-round production with high efficiency and quality is the development direction of the solar greenhouse (SG). For SG production through summer, high nighttime temperature and small temperature difference between day and night have serious negative effects on yield and quality of crops. However, nighttime cooling has not yet been paid enough attention, and leads to a lack of effective cooling methods at night. In this study, the water source heat pump system (WSHPs) was used to cool a SG at night in summer. Surface water in the protected agriculture park was used as cold source, and the heat preservation quilt was covered during cooling period. Nighttime cooling experiment of the SG was carried out from July 30 to August 30, 2015 in Changping District, Beijing. During the test, cucumbers were cultivated inside the SG. And nighttime cooling effectiveness and performance of the WSHPs were studied. The results showed that, the WSHPs could effectively decrease air temperature inside the SG during the nighttime (20:00-06:00) in summer with high ambient temperature. Nighttime mean air temperature was significantly reduced by 2.6 to 2.9 ℃ and 1.6 to 1.7 ℃ in the experimental SG with WSHPs as compared to the comparable SG with natural ventilation and outside air, respectively. However, cooling effectiveness of the WSHPs decreased as the ambient temperature got lower at night, and even indoor air temperature would be higher than ambient temperature. Nighttime mean relative humidity in the experimental SG was 74.3% to 78.6%, and 8.9% to 12.6% lower than that in the comparable SG. The CO2 concentration in the experimental SG reached 1430 to 1660 μL/L at 06:00 and was approximately 1.3 to 1.9= times that in the comparable SG, which could enhance net photosynthetic rate of the plants during a period of time after sunrise. The WSHPs ran steadily in this test, and mean power consumption was 19.3 to 19.9 W/m2 and coefficient of performance (COP) ranged from 4.1 to 4.4 for nighttime cooling. Meanwhile, there was a significant positive correlation between power consumption or COP and inlet air temperature or specific humidity (P<0.01). The amount of water drained from the WSHPs was 0.37 to 0.45 kg/(m2?d) during cooling period at night, and accounted for 18% to 21% of the amount of irrigated water. In conclusion, the WSHPs could be effectively used for the SG cooling, dehumidification, and CO2 accumulation, with a good energy-saving and water-saving performance. These results can provide theoretical basis and technical support for the WSHPs application for nighttime cooling of the SG, and give an effective microclimate control method for the SG production through summer.
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