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According to the work of Motakef and EI-Masri, the wall was divided into dry-wet-dry zones. Based on the heat and moisture transfer through porous media, considering the vapour condensation as a vapour sink, water source and heat source, coupled heat and moisture equations for wet zone were established. Closed-form analytical expressions for the condensation rate, moisture content and the time when critical moisture content value reached are obtained. It is indicated that the condensation rate exhibits a strong dependence on the temperature difference of the two sides of wet zone, and the maximum condensation rate value is reached at the boundary of wet zone close to lower temperature. 相似文献
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A coupled heat and moisture transfer model on reinforced concrete under high temperature was provided,then the heat and moisture transfer theory on reinforced concrete under fire disaster was analysed in this paper.The numerical simulation and field measurement data show that the model can roughly explain the actual heat and moisture transfer progress of reinforced concrete under fire disaster. 相似文献
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明确不同环境条件下茶鲜叶摊放过程失水动态变化规律,构建鲜叶水分含量变化的预测模型,从而有效预判摊放程度。本研究通过设置不同的温湿度,考察在一定的摊放时间内茶鲜叶水分的变化情况,利用响应面分析软件建立预测模型。结果表明,在不同环境下茶鲜叶水分含量随摊放时间的延长均呈现先快速下降后缓慢减少的趋势,且低温高湿环境能显著延缓鲜叶的失水速率。通过响应面分析得到鲜叶水分含量和温湿度、时间之间关系的预测模型(R2=0.9977),其具备较高的显著性和拟合度,且预测效果良好。构建的模型能较好地预测不同温湿度摊放环境下茶鲜叶水分的变化情况,对摊放进程的调控具有实际应用价值。 相似文献
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覆盖生态木屑对城市公园土壤温湿度的影响 总被引:3,自引:1,他引:2
为实现绿化垃圾的循环利用,量化评估覆盖生态木屑对土壤表层温湿度的影响。利用土壤温湿度计定期测定土壤表层温湿度持续1年。结果表明,冬季铺设生态木屑具有良好的保温保湿效果,不铺设木屑土壤含水率迅速下降到10%以下,铺设生态木屑15~20 cm后整个冬季土壤含水率都保持在16%以上,后者土壤温度比前者土壤温度高2℃以上。夏季铺设生态木屑5~10 cm的样树,含水率低于不铺生态木屑的对照组和其他试验组,但对温度的影响并不明显。冬季覆盖生态木屑对土壤表层具有明显的保温保湿效果,且覆盖生态木屑越厚保温保湿效果越显著;而夏季覆盖生态木屑的最佳厚度为5~10 cm,覆盖此厚度的生态木屑既可以起到海绵体吸收多余水分的作用,又不会因为覆盖生态木屑后树冠与根系间的温差增大导致的植物生理性缺水。因此,建议城市公园铺设生态木屑的厚度为5~10 cm。 相似文献
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针对加湿梗成品含水率控制稳定性差、湿透率低的问题,对稳定控制一次回潮热水温度、二次回潮蒸汽压力、二次回潮加水量环节进行了系统研究,采用统计过程控制技术对加湿梗成品含水率进行控制,以提高加湿梗含水率的稳定性。通过正交试验优化了3个主要工艺参数,并进行直观分析以及生产验证,结果表明最佳工艺组合为:一次回潮水温60℃,二次回潮蒸压力0.65 MPa,二次回潮加水量0。 相似文献
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The heat conduction characteristic of glass curtain wall was investigated. Based on one dimensional steady heat conduction theory, the numerical calculation model of glass system thermal transmittance was set up by using insulating glass as an example. Based on two dimensional steady heat conduction theory and finite element method, both the thermal transfer matrix and temperature load array of 3 DOFs triangular element were derived. Then the revised formulas about the heat transfer matrix and temperature load array under the boundary conditions of constant heat flux, heat convective, radiation and coupled of them were also derived. Then the numerical calculation models of glass curtain wall frame and linear thermal transmittance were set up. The program TJCW based on the Visual C++ and ObjectARX was developed for calculating the thermal transmittance of glass curtain wall and was validated by contrast with the results calculated by thermal software LBNL. Finally, TJCW program was used to calculate and check the thermal transmittance of glass curtain wall in a practical project. The results indicate that the thermal transmittance of glass curtain wall can be calculated correctly by adopting the presented model, and the program based on this model can be used in energy conservation calculation and analysis in the actual projects. 相似文献
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By analyzing heat and mass transport process and transport properties of moist porous media, this paper established a computational model for one dimensional field of heat and moisture transport process. Based on the distinguishing characteristic functions, the inner temperature and humidity distribution of porous media was worked out. With the actual spot measurement, the heat and moisture properties were obtained by nonlinear least square method. 相似文献
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Based on Fourier and Fick law, a modified Budaiwi model considering phase change within wall and the effect of solar radiation was established by using air humidity ratio in wall and temperature as the driving potentials.The term omitted in the mass transfer equation of the original model was added in the modified model.To evaluate the accuracy of the model, a test system was set up to measure relative humidity and temperature within a porous wall under actual weather conditions and compared with the prediction of the model.It was found that the predictions were in good agreement with the experimental results.At the interface close to outdoor, the average deviation of the relative humidity was 4.44% and average temperature deviation was 1.31K.At the interface close to indoor, the average deviation of the relative humidity was 6.3% and average temperature deviation was 1.26K. 相似文献
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本溪山区主要气象要素对水面蒸发量影响程度的灰色关联分析 总被引:1,自引:1,他引:0
为了探讨本溪山区水面蒸发量的变化特征和影响水面蒸发的主要气象因子,利用本溪市草河口气象站1953-2010年E601小型蒸发皿蒸发量、气温、降水、日照时数、相对湿度、风速和水汽压等气候资料,运用灰色关联度分析法对影响蒸发的主要气象要素进行统计分析。结果表明,本溪山区水面蒸发与气温、降水和水汽压关系比较密切,与日照时数、相对湿度和风速相关较差。影响水面蒸发的主要气象因子从大到小的排列顺序为:气温>水汽压>降水量>日照时数>相对湿度>风速。如果年平均气温升高1℃,年水面蒸发将增大66 mm;年降水量增大10 mm,水面蒸发将减少2.7 mm;年相对湿度增大1%,水面蒸发将减少16 mm;年平均风速增大1 m/s,水面蒸发量将减少154 mm。本研究揭示了主要气象因子对本溪山区水面蒸发量的影响程度,为山区水资源进一步合理开发利用提供科学的依据。 相似文献
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灌溉与秸秆覆盖条件下冬小麦农田小气候特征 总被引:20,自引:0,他引:20
采用四种灌溉方式和有无秸秆覆盖的组合处理,研究了灌溉与秸秆覆盖结合条件下冬小麦农田的小气候特征。结果表明,从2月份开始,覆盖处理在14:00时的土壤温度明显低于不覆盖处理。秸秆覆盖能够降低近地面空气湿度和提高近地面空气温度,在灌溉条件下表现尤为明显。灌溉能够降低近地面的湍流交换系数和湍流热通量,提高潜热通量,而秸秆覆盖的作用相反。秸秆覆盖具有增强灌溉水入渗能力的作用。秸秆覆盖显著降低冬小麦的产量和水分利用效率(WUE)。 相似文献
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为探讨雪茄烟支含水率与不同环境温湿度之间的关系,分别选取叶束式雪茄和叶片式雪茄两款雪茄产品,在保证烟支初始水分等其他因素一致的条件下,改变环境温湿度,测量烟支水分达到平衡时的水分值。通过烟支含水率与环境温湿度之间的相关性分析,建立不同规格雪茄烟支含水率与环境温湿度之间的线性回归方程。结果表明,在一定范围内,雪茄烟支含水率与环境温度呈负相关、与环境温度呈正相关关系。通过方差分析和残差分析对线性回归方程进行检验,并结合生产实际对回归方程进行验证。 相似文献
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微地形对大西沟野杏幼苗生境的气候和土壤温湿度的影响 总被引:1,自引:0,他引:1
摘 要:探究新疆霍城县大西沟野果林内的微地形对野杏幼苗生境的气候和土壤温湿度等环境因子的影响。在封育的野果林内设置样地,观测地形和野杏幼苗生长季的气温、光照、空气湿度和土壤温湿度,分析各环境因子和地形因子的关系。结果表明:(1)坡向与气温、光照强度和土壤温度呈极显著正相关(P<0.01),东南坡>南坡>东北坡,坡向与空气湿度、土壤含水量呈极显著负相关(P<0.01);(2)坡位与气温、光照强度呈极显著正相关(P<0.01),与土壤含水量呈显著负相关(P<0.05),不同坡位的环境因子没有显著性差异(P<0.05);(3)坡度与气温、光照强度以及土壤温度呈极显著正相关(P<0.01),缓中坡>陡坡>中坡>缓坡,缓坡与其他坡度均呈显著差异(P<0.05);坡度与空气湿度以及土壤含水量呈显著负相关(P<0.05);(4)坡形与土壤含水量呈极显著负相关(P<0.01),对气候因子和土壤温度都无显著影响。地形变化对野杏幼苗生境的气候和土壤温湿度有显著影响,东南坡、上坡位、缓中坡以及凸坡形和相应的气候与土壤温湿度,是适宜野杏幼苗生存的生境条件。 相似文献
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A theoretical model is developed for the dropwise condensation heat transfer on the horizontal circular surface with radial gradient surface energy based on the heat transfer model of individual condensate drop and the size distribution model of condensate drop on homogeneous condensation surface.The effect of variation of contact angle on the gradient surface on condensation heat transfer and condensate drop size distribution is taken account of in this model.The theoretical calculation method was obtained to predict the dropwise condensation heat transfer coefficient on the horizontal circular surface with radial gradient surface energy under various wall subcooled temperature,contact angle profile on wall surface,and working fluid.The effects of surface energy gradient,wall subcooled temperature,and thermophysical properties of condensate on the condensation heat transfer are discussed respectively.The calculation results show that the condensation heat transfer coefficient increases slightly with the increase of wall subcooled temperature.As latent heat and surface tension increasing,the condensation heat transfer coefficient increases.A larger surface energy gradient induces a larger condensation heat transfer coefficient. 相似文献