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271.
为探究采空区遗煤、松散破碎岩块对瓦斯爆炸的影响,建立缝洞型管道模型,采用数值模拟与理论分析结合方法研究采空区内缝洞型管道内瓦斯爆炸的传播规律及管道长径比对瓦斯爆炸过程中速度与冲击波的影响。研究结果表明:在缝洞型结构内,随着火焰沿管道向前传播,各监测点速度逐渐变大、压力先增加后降低,而压力上升速率则表现出不规则的变化;缝洞结构加剧了火焰燃烧的剧烈程度,提高了管道内各监测点的温度峰值;在缝洞型管道内随长径比r增加,各监测点最大压力峰值以及速度大小依次降低。 相似文献
272.
为避免地面沉降引发的油气管道事故,研究沉降管道的力学特性,提出基于谐波沉降的管道力学评估方法。以中国石化某沉降管道为研究对象,通过现场测量的方法获得沉降区管道高程,利用傅里叶级数展开对不均匀沉降数据进行处理分析,获得管道谐波沉降的拟合函数。建立ANSYS有限元模型,采用土弹簧模型模拟非沉降区管道与土体相互作用关系,将谐波沉降作为位移载荷施加到沉降区管道,对含内压管道的沉降进行数值模拟,分析其应力、应变分布规律。结果表明:沉降与非沉降交界处管道应变及应力最大,基于应变的评估准则,管道运行状态为安全,为应急响应提供支撑。 相似文献
273.
ABSTRACT Refrigerant pressure drop and temperature change in pipes are normally ignored in the thermodynamic analysis of traditional vehicle air conditioning system, this will result in serious errors. In this Paper, pressure drop and temperature difference are simulated in different pipes of electric vehicle (EV) heat pump system to analysis the effects of pipes in the actual EV heat pump system. The results indicate that the greater the mass flow, the faster pressure drop increases, the temperature difference decreases. Pressure drop of saturated liquid refrigerant is smaller than that of saturated gas refrigerant at the same saturation pressure and mass flow rate. The higher the refrigerant pressure (no phase change), the slower pressure drop decreases, the faster the temperature difference decreases. Pressure drop decreases with the increment of bending angle of the pipe. For EV heat pump system, suitable valves and less branches are helpful for energy saving of the system. Shortening the pipe between compressor and condenser can reduce temperature change obviously. Pressure drop per unit length in the pipe between evaporator and compressor is large especially in heating mode because of lower refrigerant density. It even reaches to over 100 times of that in the pipe between condenser and throttle valve in heating mode and has negative effects on the performance of the system. If the evaporator is closer to the compressor and the number of branches is less, then pressure drop will decrease a lot, which will be advantageous for energy saving of the heat pump system. 相似文献
274.
275.
Chaojin Jiang Xiaoqian Jiang Lixun Zhang Yuntao Guan 《Frontiers of Environmental Science & Engineering》2020,14(3):47
276.
Dai Wencai Holmstrup Martin Slotsbo Stine Ke Xin Li Zhu Gao Ming Wu Longhua 《Environmental science and pollution research international》2020,27(35):43638-43645
Environmental Science and Pollution Research - The impact of soil lead (Pb) pollution on survival, growth, and reproduction of the collembolan, Folsomia candida, and Pb compartmentation in its gut... 相似文献
277.
Xiao Feiyu Xu Jinmei Cao Lili Jiang Shanqing Zhang Qiuya Wang Liping 《Environmental science and pollution research international》2020,27(6):5788-5796
Environmental Science and Pollution Research - A series of g-C3N4/SrTiO3 (CN/SrTiO3) composites with the different mass ratio of g-C3N4 were prepared by facile in situ hydrothermal growth method,... 相似文献
278.
Yiming Chang Liangang Mao Lan Zhang Yanning Zhang Hongyun Jiang 《Environmental science and pollution research international》2020,27(10):10286-10295
Compound pollution refers to two or more kinds of pollutants with different properties, a pollutant from different sources, or the simultaneous existence of two or more different types of pollutants in the same environment. In this study, we aimed to investigate the individual and combined toxicity of the insecticide imidacloprid (IMI), the herbicide acetochlor (ACT), and the fungicide tebuconazole (TBZ) to zebrafish. The acute toxicity test results showed that the 96-h LC50 values of IMI, ACT, and TBZ were 276.84 (259.62–294.35) mg active ingredient (a.i.) L−1, 1.52 (1.34–1.74) mg a.i. L−1, and 8.16 (7.7–8.6) mg a.i. L−1, respectively. The combinations of IMI, ACT, and TBZ with toxicity ratios of 1:2:2, 1:4:4, 2:4:1, and 4:1:4 displayed synergistic toxic effects on zebrafish, while the toxicity ratios of 1:1:1, 1:1:2, 2:1:2, 2:2:1, and 4:2:1 of IMI, ACT, and TBZ, respectively, exhibited antagonistic toxic effects on zebrafish. The following experiments were performed with a toxicity ratio of 1:4:4 (IMI:ACT:TBZ). The activities of four enzyme biomarkers related to oxidative stress in the liver, catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), and malondialdehyde (MDA) content were evaluated in each exposure group on days 7, 14, 21, and 28. Compared with those of the control group, the activities of CAT, SOD, and GST and the MDA content were significantly altered at different time points in the individual and combined exposure groups. Additionally, the activities of CAT, SOD, and GST and the MDA content were significantly altered in the combined group compared with those of the individual group after 14 days or 21 days of exposure. Therefore, it was confirmed that combined toxicity studies are indispensable in risk assessment. 相似文献
279.
Hu Yiqin Jiang Hongying Zhong Zhangqi 《Environmental science and pollution research international》2020,27(10):10506-10519
Environmental Science and Pollution Research - Chinese industrial structure is characterized by a large proportion of industries with high energy consumption and high pollution, such as coal,... 相似文献
280.
为分析单自由度弹簧被动隔振技术的隔振机理,采用电-力导纳型类比法求得阻尼系统振动方程。利用归一化处理方法考察了在不同频率比(z)和力学品质因子(Qm)影响下,设备位移、速度、加速度的响应情况。分析发现,在z<1时,设备响应特性关系为位移>速度>加速度;在z>1时,设备响应特性关系为位移<速度<加速度;而当z=1时,设备响应特性关系为位移=速度=加速度,此时系统发生共振,且力学品质因素越大系统振动越剧烈;而当基础的干扰频率为系统固有频率的2 倍时,设备振动特性不受Qm影响,且位移、速度和加速度传递比分别为1,2 ,2。该分析结果可为动力设备布置竖向弹簧隔振支座的隔振设计提供参考。 相似文献