低温核供热堆制冷实验成功

由清华大学核能技术设计研究院负责完成的国家“八五”重点科技攻关项目—低温核供热堆制冷系统实验获得成功,填补了我国核能制冷空调的空白。该項目采用化吸收式制冷技术,用核低温堆做制冷热源,实现了利用核能夏季制冷,冬季供,一堆多用。国家教委主持的专家鉴定认为,低温     

暖通空调工程中换热器的应用分析

本文对供热工程中应用较广的三种间壁式换热器:套管式换热器、板式换热器和列管式换热器进行了换热性能的测试和探索,说明了换热器的运行节能。以供大家参考。     

快堆的燃料增殖

介绍了国外快堆增殖概论，评价了快堆的核特性以及快堆在我国核能发展中的作用。     

对流-辐射型墙面板换热器供热性能模拟

提出一种结构简单,可实现对流换热和辐射换热一体化的对流-辐射型墙面板换热器,建立其供热模型并进行试验验证,分析翅片高度、翅片间距和管中心距等对供热性能的影响。研究结果表明,3个结构参数对换热器供热性能均有一定影响:当翅片高度由20 mm增大到30 mm时,墙面板换热器单位面积总换热量增加11.9%;翅片间距由10 mm增大到20 mm,管中心距由30 mm增大到45 mm时,墙面板换热器单位面积换热量分别减少9.2%和4.3%。     

集中供热系统FBR型板式换热器及KQW系列机泵技术应用

吐哈油田哈密石油基地集中供热系统（以下简称：供热系统）一期工程为94年10月建成并投运,供热面积80多万m^2,由11台14MW热水锅炉提供热源,二次换热由9座换热站分区供热,由42台板式换热器循环换热,大部分采用对称流道的水——水型板式换热器。随着供热面积不断增加和建设时装备水平的局限性,致使水力工况和效率下降、机泵电耗上升。从2002年开始对不对称流道板式换热器研究、试验应用,至2012年9月,换热站已增加到16座,供热面积已到160．3万m^2,对10年来,技术淘汰和升级更新效果进行验证、分析,取得了较好的经济和社会效益。     

利用智能差压变送器负迁移特性实现对液位的准确测量

针对智能差压变送器在热电厂城市供热系统中换热器冷凝水液位测量的问题，说明通过智能差压变送器负迁移工作特性可实现对液位的准确测量。     

大型内压缩流程空分设备的安全探讨

结合大型内压缩流程空分设备的设计、安装和调试经验，从主换热器和主冷等4方面分析了内压缩流程空分设备的安全因素，从主换热器1％液氧的排放和临时停车的操作等7方面介绍了大型内压缩流程空分设备的安全措施。     

X研究堆热工检测系统改造的研究分析

X研究堆升级改造中较为复杂的是热工检测系统的改造。本文结合X研究堆进出口温度、主换热器二次水流量等保护变量对反应堆的停堆保护、事故监测与分析以及堆芯重水温度、工艺管温度、氦气成分、渗漏监测等重点参数监测与报警功能,对热工检测系统部分设备升级改造的特殊性与局限性进行了充分阐述,介绍了热工检测系统现场施工全过程出现的各种设计、施工、调试方面问题,并对系统改造施工重点、难点与制约因素进行总结分析。     

空分设备主换热器堵塞的原因及处理

因KDON-350／900型空分设备分子筛纯化系统前预冷器发生故障，导致水分和二氧化碳进入主换热器，并堵塞主换热器的通道。详细介绍了解决该故障的具体操作方法和步骤，简述了预冷器发生故障时的操作方法，以保证空分设备的正常运行。     

空分设备用整体式主换热器与过冷器的研制

简介空分设备中主换热器和过冷器的作用以及整体式主换热器与过冷器的优点,分析整体式主换热器与过冷器研制过程中流体流动方向和换热形式的调整策略,阐述整体式主换热器与过冷器的经济性和应用前景。     

Enhanced microbial degradation of humin-bound phenanthrene in a two-liquid-phase system

Humin, the main component of soil organic matter, greatly influences the nonlinear sorption and desorption hysteresis of polycyclic aromatic hydrocarbons (PAHs) in soil. However, little is known about the bioavailability of PAHs bound to humin. In the present study, a phenanthrene (PHE)-degrading bacterial strain--PHE9--was isolated and identified as the genus Micrococcus. It was used to investigate the degradation of humin-bound PHE and PHE not bound to humin (non-humin PHE) in liquid mineral medium (MM) and in a two-liquid-phase system (TLPs). The results showed that in MM, about 66.84% of humin-bound PHE was degraded after 49 days, whereas almost all the non-humin PHE was degraded after 27 days. Compared to MM, the TLPs showed a much better efficacy in the removal of PHE, especially for humin-bound PHE: more than 97.28% of non-humin PHE was degraded in 11 days and over 85.62% of humin-bound PHE was degraded in 32 days. It could be concluded that most of humin-bound PHE could be degraded in the MM although humin decreased the bioavailability of PHE, whereas the application of TLPs could enhance the biodegradation of humin-bound PHE.     

Adsorption of phenanthrene on activated carbon increases mineralization rate by specific bacteria

Bioavailability of polycyclic aromatic hydrocarbons (PAH) in soil is affected by PAH sorption to solid phase. We studied the influence of activated carbon (AC) on phenanthrene (PHE) mineralization by five degrading bacterial strains isolated from contaminated soil. PHE adsorption on AC was important and reduced PHE aqueous concentration up to 90%. PHE degradation was improved in the presence of activated carbon with three of the bacterial strains, named NAH1, MATE3 and MATE7, which produced biofilms, whereas it was not improved with the two other ones, which did not produce biofilms, MATE10 and MATE12. Monitoring PHE distribution during incubation showed that aqueous PHE concentration was significantly higher with the biofilm-producing NAH1 than with MATE10. Bacterial adhesion on AC was also investigated. The precoating of AC with PHE increased NAH1 and MATE3 adhesion to the solid surface (>16 and >13%, respectively). Bacterial properties, such as biofilm production and adhesion to AC capacity seemed to be related to their ability to optimize PHE degradation by improving PHE diffusion and reducing diffusion path length.     

Heterogeneous photocatalytic degradation of phenanthrene in surfactant solution containing TiO2 particles

Photocatalytic degradation of phenanthrene (PHE) over TiO(2) in aqueous solution containing nonionic surfactant micelles was investigated. All photocatalytic experiments were conducted using a 253.7 nm mercury monochromatic ultraviolet lamp in a photocatalytic reactor. The surfactant micelles could provide a nonaqueous "cage" to result in a higher degradation rate of PHE than in an aqueous solution, but the higher Triton X-100 concentration (more than 2 g/L) lowered the degradation ratio of PHE because the additional surfactant micelles hindered the movement of micelles containing PHE so as to reduce their adsorption onto titania. Pseudo-second-order kinetics was observed for the photocatalytic degradation of PHE. Alkaline solution environment was beneficial to the photocatalytic degradation of PHE. PHE degradation could mainly be attributed to the formation of hydroxyl radicals as evident from the comparison of degradation efficiencies when O(2), H(2)O(2) and tert-butyl alcohol (TBA) were applied as oxidants or hydroxyl radical scavenger. Based on the GC/MS analysis of the intermediates, the possible pathways of the photocatalytic degradation of PHE were proposed.     

Theoretical analysis of the thermal performance of a plate heat exchanger at various chevron angles using lithium bromide solution with nanofluid

Nanofluids technology has been rapidly developing over the last two decades. In this paper, the performance of a lithium bromide (LiBr) solution with and without nanoparticles in plate heat exchanger (PHE) for various chevron angles and mass flow rates was investigated. As a result, the heat transfer rate and the overall heat transfer coefficient in 60°/60° PHE is over 100% higher than that of 30°/30° PHE, and the effectiveness of the PHE in 60°/60° PHE is about 70% higher than that of 30°/30° PHE. By using nanoparticle in the working fluid, the heat transfer performance can increase significantly. The heat transfer rate of 3 vol.% nanofluids increased about 3–8% compare to that of LiBr solution for all chevron PHEs. Besides, the 60°/60° PHE using 3 vol.% nanofluids produced the largest heat transfer rate and heat exchange effectiveness under given operating conditions.     

采用新制冷剂R134a和混合制冷剂R410A的板式蒸发器性能研究

采用分布参数法对波纹型通道板式蒸发器建立数学模型,并进行了数值模拟.通过计算板内局部蒸发传热系数和压降可以简化板式蒸发器内复杂三维网状流动的传热特性.针对应用较广的R134a和R410A制冷剂来比较和分析板式蒸发器在小的温差下的传热性能.在3种不同的计算工况下简要分析了各种热力参数的变化对蒸发器整体传热性能的影响.不同的制冷剂,其传热系数和压降差别较大,相同工况下采用R410A替代R22,板式蒸发器的传热性能可提高8.5%～10.0%,且压降可大幅降低.     

Phenanthrene and pyrene uptake by arbuscular mycorrhizal maize and their dissipation in soil

Polycyclic aromatic hydrocarbons (PAHs) commonly found in soils can be degraded in rhizosphere, but may also be taken up by plants. The effects of arbuscular mycorrhizal (AM) fungi on uptake of phenanthrene (PHE) and pyrene (PYR) in maize and on their dissipation in soil were investigated using the three-compartmentalized rhizoboxes. Inoculation of Glomus mosseae significantly (p<0.01) increased PHE and PYR concentrations in maize roots and significantly (p<0.05) enhanced PYR translocation from roots to stems in the soil treatments of the PHE+PYR spiked-soils added into the central compartment of the rhizoboxes. There was a significant (p<0.05) dissipation gradient of PHE and PYR observed away from the maize roots, with the highest dissipation rates recorded in rhizosphere zone in the central compartments of the rhizoboxes, followed by near rhizosphere zone and bulk soil zone in the outer compartments. However, G. mosseae only exerted minimal impacts on dissipation of PHE and PYR in the rhizosphere. The present study suggested that the hyphae and extraradical mycelium of AM fungi could play important roles in the uptake and translocation of PHE and PYR in plants. The present results indicated that there is a potential for the use of AM fungi and plant for remediating PAHs contaminated soils.     

Surface Engineering for Extremely Enhanced Charge Separation and Photocatalytic Hydrogen Evolution on g‐C3N4

Reinforcing the carrier separation is the key issue to maximize the photocatalytic hydrogen evolution (PHE) efficiency of graphitic carbon nitride (g‐C₃N₄). By a surface engineering of gradual doping of graphited carbon rings within g‐C₃N₄, suitable energy band structures and built‐in electric fields are established. Photoinduced electrons and holes are impelled into diverse directions, leading to a 21‐fold improvement in the PHE rate.     

Synthesis of Phase Junction Cadmium Sulfide Photocatalyst under Sulfur-Rich Solution System for Efficient Photocatalytic Hydrogen Evolution

Photocatalyst with excellent semiconductor properties is the key point to realize the efficient photocatalytic hydrogen evolution (PHE). As a representative binary metal sulfide (BMS) semiconductor, cadmium sulfide (CdS) possesses suitable bandgap of 2.4 eV and negative conduction band potential, which has a great potential to realize efficient visible-light PHE performance. In this work, CdS with unique cubic/hexagonal phase junction is facilely synthesized through a sulfur-rich butyldithiocarbamate acid (BDCA) solution process. The results illustrate that the phase junction can efficiently enhance the separation and transfer of photogenerated electron–hole pairs, resulting in an excellent PHE performance. In addition, the sulfur-rich property of BDCA solution leads to the absence of additional sulfur sources during the synthesis of CdS photocatalyst, which greatly simplifies the fabrication process. The optimal PHE rate of the BDCA-synthesized phase junction CdS photocatalyst is 7.294 mmol g^–1 h^–1 and exhibits a favorable photostability. Moreover, density function theory calculations indicated that the apparent redistribution of charge density in the cubic/hexagonal phase junction regions gives a suitable hydrogen adsorption capacity, which is responsible for the enhanced PHE activity.     

Enhanced dissipation of PAHs from soil using mycorrhizal ryegrass and PAH-degrading bacteria

The major aim of this experiment was to test the effects of a multi-component bioremediation system consisting of ryegrass (Lolium multiflorum), polycyclic aromatic hydrocarbons (PAHs)-degrading bacteria (Acinetobacter sp.), and arbuscular mycorrhizal fungi (Glomus mosseae) for cleaning up PAHs contaminated soil. Higher dissipation rates were observed in combination treatments: i.e., bacteria+ryegrass (BR), mycorrhizae+ryegrass (MR), and bacteria+mycorrhizae+ryegrass (BMR); than bacteria (B) and ryegrass (R) alone. The growth of ryegrass significantly (p<0.05) increased soil peroxidase activities, leading to enhanced dissipation of phenanthrene (PHE) and pyrene (PYR) from soil. Interactions between ryegrass with the two microbes further enhanced the dissipation of PHE and PYR. Mycorrhizal ryegrass (MR) significantly enhanced the dissipation of PYR from soil, PYR accumulation by ryegrass roots and soil peroxidase activities under lower PHE and PYR levels (0 and 50+50 mg kg(-1)). The present results highlighted the contribution of mycorrhiza and PAH-degrading bacteria in phytoremediation of PAH contaminated soil, however more detailed studies are needed.     

Highly Efficient Photocatalytic Hydrogen Evolution by ReS2 via a Two‐Electron Catalytic Reaction

Highly efficient photocatalytic hydrogen evolution (PHE) is highly desirable for addressing the global energy crisis and environmental problems. Although much attention has been given to electron–hole separation, ridding photocatalysts of poor efficiency remains challenging. Here, a two‐electron catalytic reaction is developed by utilizing the distinct trion behavior of ReS₂ and the efficient reduction of two H⁺ (2H⁺ + 2e^? → H₂) is realized. Due to the monolayer‐like structure of the catalyst, the free electrons in ReS₂ can be captured by the tightly bound excitons to form trions consisting of two electrons and one hole. These trions can migrate to the surface and participate in the two‐electron reaction at the abundant active sites. As expected, such a two‐electron catalytic reaction endows ReS₂ with a PHE rate of 13 mmol g^?1 h^?1 under visible light irradiation. Meanwhile, this reaction allows the typically poor PHE efficiency of pure transition metal dichalcogenides to be overcome. The proposed two‐electron catalytic reaction provides a new approach to the design of photocatalysts for PHE.