农业工程学报2017，Vol.33Issue(16)：203-210,8.DOI:10.11975/j.issn.1002-6819.2017.16.027
日光温室墙体用相变固化土性能测试及固化机理
Performance test and curing mechanism of phase change cured soil for solar greenhouse walls
摘要
Abstract
Building solar greenhouse in these non-cultivated lands cannot only make full use of the land resources in the northwest of China,but also has great significance in ensuring national food security.However,traditional solar greenhouses with soil or brick walls often suffer from a huge energy imbalance.In In this study,we designed a phase change materials additive as a soil curing agent (PCC) and used it in sand soil (SS) and Gobi soil (GS) widely distributed in the northwest of China.The new phase change cured soil greenhouse wall materials were designed and their mechanical and thermal properties were evaluated and the curing mechanism was also studied.The main composition of phase change curing agent included phase change material,silicate cement (PO32.5) and powdered Ca(OH)2 at a ratio of 3 ∶ 25 ∶ 5.The raw phase material was Na2SO4·10H2O ∶ Na2HPO4·12H2O ∶ CaCl2·6H2O ∶ Na2B4O7·10H2O ∶ CMC =20∶70 ∶ 8 ∶ 1∶ 1.Allthe materials were stored at room temperature before use.The sand soil had the optimal water content of 12％ and the dry density of 1.92 g/cm3 of density.The sample Gobi soil had the water content and dry density of 15％ and 2.12 g/cm3,respectively.The phase changed cured soil with 5％ PCC in SS,10％ PCC in SS,5％ PCC in GS and 10％ PCC in GS was prepared with 3 replicates for each treatment.The compressive strength was tested at room temperature.The thermal property was studied by differential scanning calorimetry method.The structure of soil was measured by an electron microscope.The results showed that the average compressive strength of 5％ PCC + SS was 1.667 MPa,higher than the international standard for curing sand (1 MPa) and the non-additive SS (0.045 MPa).The average compressive strength of 10％ PCC + SS was 3.208 MPa,which almost doubled that of 5％ PCC + SS.The compressive strength for 5％ PCC+ GS and 10％ PCC+ GS was 2.454 and 3.671 MPa,respectively,which were both higher than the average compressive strength of GS (1-1.5 MPa).Both endothermic and exothermic processes appeared in the greenhouse.For the 5％ PCC + SS,the endothermic process was from 6.54 ℃ to 42.68 ℃.The maximum endothermic temperature was 33.59 ℃,with the heat absorption of 28.16 J/g.The exothermic process started at 17.12 ℃ and ended at 1.59 ℃.The maximum exothermic temperature was 16.42 ℃ and the overall exothermic volume was 29.89 J/g.In contrast,the heat flow change of the 10％ PCC + SS was relatively small.For 5％ PCC + GS,an overall similar endothermic and exothermic process was also observed.The endothermic process started at 13.20 ℃ and ended at 37.79 ℃.The maximum endothermic temperature was 31.04 ℃,and the heat absorption was 13.55 J/g.The exothermic started at 15.50 ℃ and ended at 0.05 ℃.The maximum exothermic temperature was 13.73 ℃ and the heat absorption was 12.69 J/g.The heat flow change of the 10％ PCC + GS was also very small.These results indicated that 5％ PCC and 10％ PCC both met the requirement of the greenhouse energy storage.Adding of PCC enhanced the poor connection of original particleS into cementation connection,thereby reducing the holes,enhancing mechanical strength and heat storage.This paper provided valuable suggestions for the utility of SS and GS as fundamental structural materials of solar greenhouses,especially in the wild northwest regions.关键词
相变材料/土壤/温室/固化剂/抗压强度/DSC/固化机理Key words
phase change materials/soils/greenhouse/SCA/compressive strength/DSC/curing mechanism分类
农业科技引用本文复制引用
鲍恩财,邹志荣,张勇..日光温室墙体用相变固化土性能测试及固化机理[J].农业工程学报,2017,33(16):203-210,8.基金项目
国家“863”计划项目(2013AA102407) （2013AA102407）
中国博士后基金项目特别资助(2015T81053) （2015T81053）
博士后科学基金(2014M562458) （2014M562458）
主动采光蓄热温室、超大跨度塑料大棚结构优化与智能化环境调控装备研制(2016BZ0901) （2016BZ0901）
设施农业采光蓄热技术提升研究与示范(2016KTCL02-02) （2016KTCL02-02）
