Analysis of Solar Direct-Driven Organic Rankine Cycle Powered Vapor Compression Cooling System Combined with Electric Motor for Office Building Air-Conditioning

Solar energy powered organic Rankine cycle vapor compression cycle(ORC-VCC)is a good alternative to convert solar heat into a cooling effect.In this study,an ORC-VCC system driven by solar energy combined with electric motor is proposed to ensure smooth operation under the conditions that solar radiation is unstable and discontinuous,and an office building located in Guangzhou,China is selected as a case study.The results show that beam solar radiation and generation temperature have considerable effects on the system performance.There is an optimal generation temperature at which the system achieves optimum performance.Also,as a key indicator,the cooling power per square meter collector should be considered in the hybrid solar cooling system in design process.Compared to the vapor compression cooling system,the hybrid cooling system can save almost 68.23%of electricity consumption.

Fractal Image Compression Using Self-Organizing Mapping

One of the main disadvantages of fractal image data compression is a loss time in the process of image compression (encoding) and conversion into a system of iterated functions (IFS). In this paper, the idea of the inverse problem of fixed point is introduced. This inverse problem is based on collage theorem which is the cornerstone of the mathematical idea of fractal image compression. Then this idea is applied by iterated function system, iterative system functions and grayscale iterated function system down to general transformation. Mathematical formulation form is also provided on the digital image space, which deals with the computer. Next, this process has been revised to reduce the time required for image compression by excluding some parts of the image that have a specific milestone. The neural network algorithms have been applied on the process of compression (encryption). The experimental results are presented and the performance of the proposed algorithm is discussed. Finally, the comparison between filtered ranges method and self-organizing method is introduced.

Improve Fractal Compression Encoding Speed Using Feature Extraction and Self-organization Network

Image compression consists of two main parts: encoding and decoding. One of the important problems of the fractal theory is the long encoding implementation time, which hindered the acceptance of fractal image compression as a practical method. The long encoding time results from the need to perform a large number of domain-range matches, the total encoding time is the product of the number of matches and the time to perform each match. In order to improve encoding speed, a hybrid method combining features extraction and self-organization network has been provided, which is based on the feature extraction approach the comparison pixels by pixels between the feature of range blocks and domains blocks. The efficiency of the new method was been proved by examples.

Performance comparison and analysis of a combined power and cooling system based on organic Rankine cycle

A novel power and cooling system combined system which coupled organic Rankine cycle(ORC) with vapor compression refrigeration cycle(VCRC) was proposed. R245 fa and butane were selected as the working fluid for the power and refrigeration cycle, respectively. A performance comparison and analysis for the combined system was presented. The results show that dual-pressure ORC-VCRC system can achieve an increase of 7.1% in thermal efficiency and 6.7% in exergy efficiency than that of basic ORC-VCRC. Intermediate pressure is a key parameter to both net power and exergy efficiency of dual-pressure ORC-VCRC system. Combined system can produce maximum net power and exergy efficiency at 0.85 MPa for intermediate pressure and 2.4 MPa for high pressure, respectively. However, superheated temperature at expander inlet has little impact on the two indicators. It can achieve higher overall COP, net power and exergy efficiency at smaller difference between condensation temperature and evaporation temperature of VCRC.

Assessment of strength development in cement-admixed artificial organic soil with GX07

To explore the stabilization effect of stabilizing agent GX07 on treating organic soil and the influence of organic matter on the strength development of stabilized soil,artificial organic soil with various organic matter content was obtained by adding different amounts of fulvic acid into non-organic clay,and then liquid-plastic limit tests were carried out on the artificial organic soil.Meanwhile,unconfined compressive strength(UCS) tests were performed on cement-only soil and composite stabilized soil,respectively.The test results indicate that the plastic limit of soil samples increases linearly,and the liquid limit increases exponentially as the organic matter content increases.The strength of stabilized soil is well correlated with the organic matter content,cement content,stabilizing agent content and curing time.When the organic matter content is 6%,as the cement content varies in the range of 10%-20%,the strength of cement-only soil increases from 88.5 to 280.8 kPa.Once 12.6% GX07 is added into the mix,the strength of stabilized soil is 4.93 times compared with that of cement-only soil.GX07 can obviously improve the strength of cemented-soil and has a good economic applicability.A strength model is proposed to predict strength development.

Effect of Organic Waste on Crystal Structure and Mechanical Properties of Concrete

The influence of organic waste as an additive to concrete formulation has been studied by replacing up to 10% of cement ratio with locally sourced organic additive. The reference cement used was Portland cement;three different organic wastes were used in the mixture: periwinkle shell, extracted silica from corn hob ash and coconut shell ash. Uniform distribution of the additive was ensured by thorough mixing prior to water addition. Casting and curing of the concrete were done in line with established standard. The compressive strength test was carried out using the Instron universal testing machine and the oxides of elemental composition of the cement and the additives were determined using EDXRF Spectrometer (EDX 3600B) while the crystallography studies were carried out using EMMA) X-ray diffractometer . The result obtained indicated that there was a significant difference between the value of density, packing efficiency and compressive strength of each reinforced concrete with that of the reference cement which was attributable to the presence of additives. The cement formulation with silica as admixture was found to have the highest compressive strength of 217.94 MPa, while the reference cement had the lowest compressive strength of 81.45 MPa. This study has established that locally sourced organic additives (emerging additives), influence the mechanical properties of concretes.

Metastatic Spinal Cord Compression (MSCC) —The Evolving Story from Kashmir

Aim: To know the demographics of the patients most commonly involved by metastatic cord compression in Kashmir and to find the commonest primary organ to metastasize to spine causing cord compression. Methods: A hospital-based 10-year retro-prospective study was carried out in the Department of Neurosurgery of Sher-i-Kashmir Institute of Medical Sciences, Soura from July 2002 to June 2012, which is the premier tertiary care institute of the Kashmir valley. Patients were evaluated for metastatic spinal cord compression based on a standard proforma and specialized investigations were carried out and were deemed necessary by the concerned neurosurgical unit. Results: The commonest primary malignancy to metastasize to the spinal column in our study was Non-Hodgkin’s lymphoma, followed in turn by metastatic squamous cell carcinoma lung, metastatic intraductal carcinoma breast and metastatic adenocarcinoma prostate. Predominantly dorsal spine was the commonest region of spine involved by MSCC. Conclusion: Metastatic spinal cord compression is coming up in a big way. As the long-term cancer survivors increase due to multi-modality treatment protocols aimed at treating cancers and prolonging survival, there will be a proportionate increase in the number of patients who will potentially land up in metastatic spinal cord compression.

有机醇胺TEA-M-无机盐体系对固硫灰渣活性激发的影响

固硫灰渣的处理以及环保型激发剂材料的开发是防止环境二次污染的有效途径。本文开发了一种有机醇胺TEA-无机激发剂M-无机盐复合激发剂,通过SEM、FTIR、XRD等测试方法对所制备的复合激发剂进行表征,先后探索了M、TEA-M、TEA-M-无机盐三个系列的激发剂对水泥胶砂流动度比和抗压活性指数的影响。结果表明,TEA的助磨作用改善了颗粒的粒径,无机激发剂M能影响参与水化反应的Ca(OH)_(2)含量,无机盐CaSiO_(3)后期会产生C-S-H并提供碱性条件。复合激发剂中的不同材料间的协同作用使水泥胶砂7和28 d的抗压活性指数分别提高了29个和18个百分点(与空白样相比),并且胶砂净浆的流动度比仍然保持在较高水平。本文为固硫灰渣提供了一种环保型的复合激发剂材料,促进了固硫灰渣的绿色化应用。

利用ORC-VCR回收压缩热的预冷式CAES系统性能分析

常规非绝热压缩空气储能(D-CAES)系统的储能过程通常采用四级以上的压缩机组以减少空气压缩功的消耗,导致产生大量的低品位压缩热直接排放到环境中,能源浪费严重。针对这一问题,本工作提出了一种采用有机朗肯循环-蒸汽压缩制冷(ORC-VCR)回收压缩热的预冷式CAES系统(ORC-VCR-CAES),通过回收空气压缩阶段压缩机产生的压缩热来对压缩机入口空气进行预冷,可以进一步降低空气压缩功的消耗,提高系统的循环效率。对ORC-VCR-CAES耦合系统进行了热力学分析和经济性分析。结果表明,不同ORC-VCR循环工质对系统性能的影响较大,采用R152a作为循环工质的ORC-VCR-CAES系统综合性能最佳。其系统循环效率可达64.15%,比常规D-CAES系统提高了5.94%;在考虑外部废热能量输入时,ORC-VCR-CAES系统(火用)效率为51.90%,比常规D-CAES系统提高了4.81%。通过压缩热的回收有效减少了冷却器的(火用)损失,但压缩机组的(火用)损失仍然较大,是系统进一步优化的关键部件;经济性分析表明,当峰谷电价为1.26元和0.30元时,ORC-VCR-CAES系统的项目净现值相比于常规D-CAES系统可增加12.48%,且峰谷电价差越小,ORC-VCRCAES相比于常规D-CAES系统的项目净现值增加百分比越高。

有机模板孔径和烧结温度对SiC泡沫陶瓷结构和性能影响

SiC泡沫陶瓷作为一种新型多孔材料,因其强度高、硬度高、耐腐蚀、耐高温等优异性能,被广泛应用于冶金、石油化工、航空航天、生物医学等领域。以SiC为主要原料,Al_(2)O_(3)为烧结助剂,采用有机模板浸渍法制备了SiC泡沫陶瓷,研究了有机模板孔径和烧结温度对SiC泡沫陶瓷宏微观形貌、相组成、孔隙率及压缩性能的影响。结果表明:随着有机模板孔径由35 ppi增至20 ppi,SiC泡沫陶瓷的孔隙率由48.3%升至75.6%,而抗压强度由1.94 MPa降至0.40 MPa。随着烧结温度由1350℃提高至1500℃,SiC泡沫陶瓷的孔隙率由78.7%降至68.3%,抗压强度先升后降。在1450℃制备的SiC泡沫陶瓷样品抗压强度最高(1.45 MPa),其孔隙率为71.6%,孔结构完整、颗粒堆积紧密,针眼孔洞、裂纹以及脆性方石英相较少。

铅锌冶炼渣基胶凝材料固化电镀污泥研究

电镀污泥是含有各类重金属的危险废物。本文利用铅锌冶炼渣制备胶凝材料,评估该胶凝材料对固化电镀污泥效果,并阐明了有机聚合物对固化过程的影响机制。结果表明,在碱含量为3.5%(质量分数)、水玻璃模数1.4、液固比0.22条件下,铅锌冶炼渣基胶凝材料可安全固化2.5%(质量分数)的电镀污泥;与未加有机聚合物相比,加入有机聚合物后复合胶凝材料对电镀污泥的固化量提高一倍,同时抗压强度提高27.45%,此时总Cr浸出浓度从20.05 mg/L降低至13.65 mg/L,低于《危险废物鉴别标准浸出毒性鉴别》(GB 5085.3—2007)规定的限值。固化体的矿物组成、微观形貌、化学键和原子价态分析表明,在铅锌冶炼渣中Fe(II)和有机聚合物共同作用下,能有效降低Cr毒性,提高重金属离子固定率。本研究为安全处置电镀污泥及综合利用铅锌冶炼渣提供了新思路。

铜尾矿浆絮凝沉降及对固化影响研究

为研究不同絮凝剂单掺及复配对铜尾矿浆的絮凝沉降效果,选用传统无机絮凝剂硫酸铝、无机高分子絮凝剂聚合氯化铝(PAC)及有机絮凝剂阴离子聚丙烯酰胺(APAM)进行单掺及2种无机絮凝剂分别与APAM复配絮凝沉降试验,并将絮凝后的铜尾矿浆进行水泥固化试验。结果表明:在最佳投加量时,3种絮凝剂絮凝效果为APAM>PAC>硫酸铝。在复配试验中,复配组合的沉降效果均优于单独使用。絮凝前后的铜尾矿固化体抗压强度各龄期最低提高了2.4倍,其中,单独使用絮凝剂硫酸铝后的铜尾矿固化体各龄期抗压强度最高,APAM最低;而在复配絮凝剂中,硫酸铝与APAM絮凝后的铜尾矿固化体抗压强度较PAC与APAM絮凝后的高。

海相淤泥质固化土强度劣化规律试验研究

针对海相淤泥质软土中水泥搅拌桩成桩效果不佳的问题,选取天津地区某地铁工程施工现场海相淤泥质黏土,通过室内水泥土无侧限抗压强度试验,研究了可溶性盐和有机质含量对海相淤泥固化的无侧限抗压强度(UCS)的影响,并通过扫描电镜(SEM)和X射线衍射(XRD)对其微观结构和物相特征进行分析。结果表明:土壤水泥的强度随可溶性盐和有机质含量的增加而降低,其主要通过破坏和抑制水泥水化产物的形成,进而降低水化产物的胶凝性能,破坏了水泥土结构,导致强度降低。该研究结果对解释海相淤泥质软土固化效果不佳的现象具有重要的意义。

Compressive and tensile strength of polymer-based fiber composite sand

Traditional soil additives like Portland cement and lime are prone to cause the brittle fracture behavior of soil,and possibly,environmental impacts.This study explores the potential use of polyurethane organic polymer and sisal fiber in improving the mechanical performance of sand.The effects of polymer content,fiber content,and dry density on the unconfined compressive strength(UCS)and direct tensile strength(DTS)of the polymer-fiber-sand composite were evaluated.The results showed significant increase in UCS and DTS of the reinforced sand with the increase of polymer content,fiber content,and dry density.At high dry density condition,a single peaked stress−strain curve is often observed.Higher polymer content is beneficial to increasing the peak stress,while higher fiber content contributes more to the post-peak stress.The combined use of polymers and fibers in soil reinforcement effectively prevents the propagation and development of cracks under the stress.Scanning electron microscopy(SEM)test was also performed to investigate the micro-structural changes and inter-particle relations.It was found through SEM images that the surface coating,bonding,and filling effects conferred by polymer matrix greatly enhance the interfacial interactions,and hence provide a cohesive environment where the strength of fibers could be readily mobilized.

Effects of Sand Quality on Compressive Strength of Concrete: A Case of Nairobi County and Its Environs, Kenya

Failure of concrete structures leading to collapse of buildings has initiated various researches on the quality of construction materials. Collapse of buildings resulting to injuries, loss of lives and investments has been largely attributed to use of poor quality concrete ingredients. Information on the effect of silt and clay content and organic impurities present in building sand being supplied in Nairobi County and its environs as well as their effect to the compressive strength of concrete was lacking. The objective of this research was to establish level of silt, clay and organic impurities present in building sand and its effect on compressive strength of concrete. This paper presents the findings on the quality of building sand as sourced from eight supply points in Nairobi County and its environs and the effects of these sand impurities to the compressive strength of concrete. 27 sand samples were tested for silt and clay contents and organic impurities in accordance with BS 882 and ASTM C40 respectively after which 13 sand samples with varying level of impurities were selected for casting of concrete cubes. 150 mm × 150 mm × 150 mm concrete cubes were cast using concrete mix of 1:1.5:3:0.57 (cement:sand:coarse aggregates:water) and were tested for compressive strength at the age of 7, 14 and 28 days. The investigation used cement, coarse aggregates (crushed stones) and water of similar characteristics while sand used had varying levels of impurities and particle shapes and texture. The results of the investigations showed that 86.2% of the sand samples tested exceeded the allowable limit of silt and clay content while 77% exceeded the organic content limit. The level of silt and clay content ranged from 42% to 3.3% for while organic impurities ranged from 0.029 to 0.738 photometric ohms for the unwashed sand samples. With regard to compressive strength, 38% of the concrete cubes made from sand with varying sand impurities failed to meet the design strength of 25 Mpa at the age of 28 days. A combined regression equation of with R2 = 0.444 was generated predicting compressive strength varying levels of silt and clay impurities (SCI), and organic impurities (ORG) in sand. This implies that 44% of concrete’s compressive strength is contributed by combination of silt and clay content and organic impurities in sand. Other factors such as particle shapes, texture, workability and mode of sand formation also play a key role in determination of concrete strength. It is concluded that sand found in Nairobi County and its environs contain silt and clay content and organic impurities that exceed the allowable limits and these impurities result in significant reduction in concrete’s compressive strength. It is recommended that the concrete design mix should always consider the strength reduction due to presence of these impurities to ensure that target strength of the resultant concrete is achieved. Formulation of policies governing monitoring of quality of building sand in Kenya and other developed countries is recommended.

黄河口有机质疏浚土压缩特性及改良利用研究

疏浚土是一种性质复杂和分布不均的材料,为研究含有机质疏浚土的压缩特性及相应的改良方案,通过试验确定了0%~11%有机质含量下天然疏浚土的工程指标,采用扫描电镜(SEM)和X射线荧光光谱分析(XRF)对疏浚土的微观结构及矿物成分进行了分析,并通过一维固结试验,分析了添加石灰、粉煤灰、火山灰等改良材料的疏浚土的压缩特性,探讨了有机质含量对改良效果的影响。研究表明:随着有机质含量的增大,天然疏浚土的界限含水率增大,密度减小,碱性由中碱性变为微碱性,天然疏浚土的压缩指数范围在0.10~0.32之间,压缩性和膨胀性越来越高;添加石灰和粉煤灰都可以有效提高疏浚土的抗压缩性,其中粉煤灰对各有机质含量的疏浚土均有明显改良效果,当其含量在15%以上时,可以大大降低疏浚土压缩性;火山灰添加后体积压缩系数、压缩指数反而增大,说明其对抗压缩产生了不利的影响。研究结果可为水运工程中疏浚土的建材化利用提供参考。

Ⅰ型有机质生油增压数学模型建立与应用

生油增压定量化研究是计算油气成藏动力并进一步确定油气分布的关键。目前已有的生油增压计算方法较复杂或计算精度不足,影响其在勘探中快速应用。基于Ⅰ型有机质生烃特征综合分析,建立了生油增压数学模型,并将该模型应用于鄂尔多斯盆地西峰油田长7段烃源岩生油增压的计算,同时分析了不同参数对生油增压的影响。结果显示,西峰油田长7段烃源岩生油增压为4.6~14.8 MPa,地层压力与前人计算结果相近,说明模型具有较高的可靠性。参数敏感性分析表明,岩石压缩系数对生油增压影响程度最大,为99.056%;总有机碳含量影响程度为0.342%;生烃影响因子和干酪根生油转化效率对生油增压的影响程度分别为0.261%和0.250%;孔隙度和地层压力对生油增压的影响程度较小,分别为0.09%和0.001%。模型同时揭示,较高的地层压力不利于生油增压,地层压力越高,增压越小。

有机聚合物复合纤维改良砂土无侧限抗压强度研究

为研究有机聚合物复合纤维改良砂土的抗压特性、变形规律与改良机理,通过无侧限抗压强度试验和数值模拟分析了改良砂土抗压变形过程的力链变化与微裂纹发育规律,给出了改良砂土的破坏与改良机理。结果表明:有机聚合物复合纤维能够有效提升砂土的抗压强度,随着有机聚合物含量的增大,改良砂土的无侧限抗压强度逐渐提高;随着有机聚合物含量与应变增大,改良砂土的力链演化与微裂纹发育明显改变,力链由环状和柱状结构转变为拱状结构,微裂纹总数量及张拉微裂纹增多,破坏由单一路径向多路径转变。有机聚合物复合纤维黏结、包裹砂粒以及三者相互耦合胶结有效提升了砂土的抗压特性;当荷载过大时,有机聚合物膜发生破裂,纤维逐渐断裂与滑脱,改良砂土网状结构逐渐失稳,砂粒被迫发生位移与旋转,形成局部微裂纹,最终发育、延伸形成裂隙造成破坏。

两级蓄冷跨临界压缩CO_(2)混合工质储能系统特性分析

为了解决高压CO_(2)在高环境温度下难以冷凝的问题,提出两级蓄冷跨临界压缩CO_(2)混合工质储能系统。采用CO_(2)与低沸点有机工质混合的方法提高工质的冷凝温度,同时,利用两级甲醇蓄冷实现系统内部冷能循环利用。从环境性、临界温度、温度滑移、可混合性等方面确定合适的CO_(2)混合工质及其组分质量分数范围。建立储能系统的热力学分析模型,探究节流压力、高压储液罐压力、有机工质质量分数等关键参数对系统性能的影响规律,并研究系统内部能量流动规律,得到主要部件的(火用)损失。研究结果表明:随着有机工质质量分数的增加,蓄冷介质温度增加,系统安全性提高;与纯CO_(2)工质相比,系统的充放电效率和能量密度略有降低;CO_(2)/R32混合工质的充放电效率最高为62.29%,CO_(2)/pentane混合工质的能量密度最高为21.37 kW·h/m^(3)。

非共沸工质分离压缩再混合有机朗肯循环综合性能分析

为利用非共沸工质在蒸发器内“温度滑移”的优势,避免在冷凝器内“组分迁移”的不利影响。构建了非共沸工质分离压缩再混合有机朗肯循环系统(ORC with separation,compression,and remixing,SCRM-ORC)。采用分凝器将非共沸混合工质分离成2种纯工质,分别进入气液热交换器两空间进行气液换热,再对纯工质压缩、混合再利用。以120℃地热水为热源,R134a/R245fa为工质,建立热力、经济与环境性能模型,分析R134a质量分数对系统综合性能的影响,并与采用R134a的乏气压缩再循环ORC系统(compression recycling,CR-ORC)性能进行对比。采用遗传算法进行多目标优化,揭示系统最优性能与工况参数。结果表明:与CR-ORC系统相比,非共沸工质SCRM-ORC系统可有效降低冷凝热的释放量,在R134a质量分数较低时提高冷凝热回收利用量,同时具有较好的综合性能。将分凝器与气液热交换器看作整体与CR-ORC系统中新型冷凝器相比,二者[火用]损失之和与投资成本之和小于CR-ORC系统中冷凝器的。在R134a质量分数为0.2181时,系统综合性能最优,此时净输出功为3412.1kW,投资回收期为2.237年,年当量CO_(2)减排量为4520.6×10^(3)kg。