A numerical model for drying of spherical object in an indirect type solar dryer and estimating the drying time at different moisture level and air temperature

A numerical model for simultaneous heat and mass transfer was developed for solar drying of spherical objects and the object considered is green peas. Solar collector outlet temperature is assumed as drying chamber temperature and justified through energy balance equations. Assumptions are imposed on heat and mass transfer governing equations without losing the physics of the problem. Discretization is performed by finite difference method with implicit scheme. To generalize, the governing equation and boundary conditions are non-dimensionalized. The set of finite difference equations was solved by Tridiagonal Matrix Algorithm and a computer code in MATLAB was developed to solve them. The drying curves showed two stages of drying, initial, and secondary drying stage. At all drying temperatures and drying time, the center moisture was maximum and it was minimum at the boundary. A percentage of 85.67 surface moisture content and 25.33% center moisture was eliminated in the first 1 hr at 348 K. The product should be dried up to 7.45, 4.74, and 3.74 hr at air drying temperatures of 318, 333, and 348 K respectively, to maintain 10% of the product’s initial moisture content. The result is compared with the experimental result from literature and they are found to be in good agreement.     

LCA-Based Economic Benefit Analysis for Building Integrated Photovoltaic (BIPV) Façades: A Case Study in Taiwan

Solar energy is one of the major sources of alternative and green energies that humanity need now and will continue to need in the future. There are now a large number of R&D activities on solar power generation facilities and equipment around the world. Located in a subtropical region, Taiwan is rich in solar energy resources; therefore, how to effectively use and store solar energy is a research topic of great interest to Taiwan. The main purpose of this study explores the economic benefits of building-integrated photovoltaics (BIPV) facilities and equipment by analyzing the net present values (NPV) and payback period of the BIPV façade of a shopping mall in Taiwan over its lifecycle. The NPV and payback period analysis results both indicate that the BIPV façade in the case study reaches its breakeven point within 10 years of payback period and 16 years of NPV during a life cycle of 20 years. By showing BIPV investments can bring an acceptable range of benefits profits, this study hopes to provide references for promoting the photovoltaic (PV) industry.     

两起突发辐射环境事件的模拟监测

近两年来四川省成都、绵阳两市相继发生两起辐射环境事件,为澄清事实,消除公众疑虑,四川省辐射环境管理监测中心站对两事件分别开展模拟监测。着重介绍两事件的模拟监测情况,并对事件的影响进行评估。最终消除了公众的疑虑,维护了社会稳定。     

Larval performance of the mustard leaf beetle (Phaedon cochleariae, Coleoptera, Chrysomelidae) on white mustard (Sinapis alba) and watercress (Nasturtium officinale) leaves in dependence of plant exposure to ultraviolet radiation

Short-term exposure to ambient or attenuated ultraviolet (UV) radiation resulted in shifts in plant metabolite concentrations of the Brassicaceae Sinapis alba and Nasturtium officinale. Leaf quality also varied between plant species and within species due to age. Larvae of the oligophagous leaf beetle Phaedon cochleariae were raised on these different host leaves, in order to investigate the effects of variable plant chemistry on this herbivore. The performance of P. cochleariae was influenced by chemical differences between and within plant species but it responded with high plasticity to plants stressed by ultraviolet radiation. Body mass increase and developmental times of larvae were exclusively affected by plant species and leaf-age. However, developmental differences were fully compensated in the pupal stage. We suggest that the plasticity of herbivores may depend on the degree of specialisation, and insect performance may not necessarily be altered by stress-induced host plants.     

苍山5.2级地震前电磁辐射异常

利用枣庄电磁信息台ＤＰＪ Ⅲ、ＵＬＦ Ⅲ及ＪＤ ０３型电磁辐射仪观测到的资料，分析了山东苍山５．２级地震前多数台站记录到的异常信息及其特征。     

Studies of the effects of temperatures and solar radiation on volatilization,mineralization and binding of 14c‐DDT in soil under laboratory conditions

Abstract

The effects of temperatures and solar radiation on the dissipation of ¹⁴C‐p,p'‐DDT from a loam soil was studied by quantifying volatilization, mineralization and binding. The major DDT loss occurred by volatilization, which was 1.8 times more at 45^oC than at ambient temperature (30°C). Mineralization of DDT slowly increased with time but it decreased slightly with increase in temperature. Binding of DDT to soil was found to be less at higher temperatures (35 and 45°C) as compared to ambient temperature. Degradation of DDT to DDE was faster at higher temperatures.

Exposure of non‐sterilized and sterilized soils treated with ¹⁴C‐DDT to sunlight in quartz and dark tubes for 6 weeks resulted in significant losses. Volatilization and mineralization in quartz tubes were more as compared to dark tubes. The volatilized organics from the quartz tubes contained larger amounts of p,p'‐DDE than the dark tubes. Further, higher rates of volatilization were found in non‐sterilized soils than in sterilized soils. The results suggest that faster dissipation of DDT from soil under local conditions relates predominantly to increased volatilization as influenced by high temperature and intense solar radiation.     

内蒙古草原光合有效辐射的计算方法

2002年夏季,对内蒙古草原太阳分光辐射以及气象因素进行了同步观测。依据一定的物理基础,在对实测资料进行分析的基础上,计算得到了内蒙古草原地区光合有效辐射某一时段累计值的经验公式。实际天气条件下,计算结果与观测值比较接近,该经验公式的适用性亦比较好。根据不同条件,可以选择不同的因子来计算光合有效辐射。当选择全部因子时,计算值与观测值的最大相对偏差为8 13%,平均相对偏差为2 45%。研究表明,大气中所有物质对光合有效辐射的吸收作用小于它们的散射作用。      

水翁(Cleistocalyx operculatus)在人工湿地的生长特性及对污染物的去除效果

研究了水翁在人工湿地的生长特性及其对污水的净化效果.结果表明:生长在人工湿地的水翁具有发达的侧根系,能保持正常的净光合速率((19.2±2.1)μmol/(m2·s))、蒸腾速率((23.5±2.3)mmol/(m2·s))、气孔传导率((657.5±53)mmol/(m2·s))、根系活力((20.9±3.2)μg/(g·min))和生长速率((9.9±0.5)mg/(g·d)).水翁人工湿地对TN,TP,C0D_cr和BOD₅的去除率分别为55.6%,44.2%,75.7%和73.2%.其中水翁对N,P的吸收量分别占人工湿地对N,P去除量的16.4%和12.6%.水翁为常绿乔木,可考虑与灌木和草本植物结合起来,建立乔、灌、草自然湿地系统,达到改善水质的目的.      

三相内循环流化床光催化反应器及其光辐射传递规律

提出并建立了三相内循环流化床光催化反应器 ,对其内部光辐射传递规律进行了研究 .结果表明 ,在气固相共同作用下(通气量>0.3m³/h) ,光强的径向分布服从指数衰减规律 ,与Rose公式中通过均匀悬浊介质时的光强分布规律一致 .光辐射能的数值受初始光强 .催化剂颗粒浓度和液层厚度的共同影响 .通气量只影响床层流化状态 ,对光强分布影响可以忽略 .对罗丹明B的光催化降解实验表明 ,三相内循环流化床的光催化效率高于传统的悬浆式反应床 ,本系统的最佳催化剂浓度为10～12g/L .     

172nm真空紫外辐射降解水相有机染料的机理研究

研究了氙准分子灯的172nm真空紫外辐射对水相有机染料枣红的分解机理.氙准分子灯为平面状结构,反应溶液作为灯的一端电极直接与灯表面接触.分别在枣红溶液中通入氧气和氮气以及加入KCl,以具体确定172nm辐射对枣红分子的降解是通过直接光分解还是自由基起作用.研究结果表明,在枣红的降解过程中,直接光分解起主要作用,光降解过程符合准一级动力学反应,光量子产率为6 8×10 - 3mol·eistein- 1 .在HO·、HO2 ·和O2 ·- 自由基作用下,枣红的降解在10min后偏离了准一级反应.枣红降解效率达到约80 %后,COD去除率开始增大.GC MS分析表明,在光分解和热氧化作用下,枣红分子在降解过程中形成了许多小分子碎片.