Thermodynamic and Experimental Analysis of an Ammonia-Water Absorption Chiller

A single stage ammonia-water absorption chiller with complete condensation is designed, built and tested. The apparatus is designed for a cooling capacity of 2814 W, which is obtained using electric heater as heating source. The thermodynamic models have been derived using the First and Second Laws. Calculated results are compared with experimental data. The results show that the cooling capacity of experimental apparatus is found between 1900 and 2200 W with the actual coefficient of performance (COP) between 0.32 and 0.36. The contribution of the components to internal entropy production is analyzed. It shows that the larger irreversibility is caused by spanning the largest temperature and dissipated thermal energy by heat transfer losses at the generator and evaporator. In the experimentation, the low pressure is lower than the designed value. This is a consequence of a large capacity in the falling film absorber which performs as expected. This decreases the evaporation pressure, and the evaporating temperature could be reduced to the designed value.

Magnetic Field Enhancement in Ammonia-Water Absorption Refrigeration Systems

Absorption enhancement has been considered as an effective way of improving coefficient of performance (COP) of refrigeration systems and magnetic enhancement is one of these methods. A model of magnetic field enhancement in ammonia-water absorption systems is presented in this paper. A numerical model using finite difference scheme was developed based on the conservation equations and mass transport relationship. Macroscopic magnetic field force was introduced in the momentum equation. The model was validated using data obtained from the literature. Changes in the physical properties of ammonia solution while absorbing both in the direction of falling film and across its thickness were investigated. The magnetic field was found to have some positive effect on the ammonia-water falling film absorption. The results indicate that absorption performance enhancement increased with magnetic intensity. The COP of simple ammonia solution absorption refrigeration system increased by 1.9% and 3.6% for magnetic induction of 1.4 and 3.0 Tesla respectively.

The application study of polycarboxylates water-reducing admixture in passenger dedicated line engineering

Polycarboxylate water-reducing admixture possesses the capability which could meet with the comprehensive performance of high performance concrete used in passenger dedicated line engineering.The problems of polycarboxylates water-reducing admixtures existed in the engineering application of were analyzed.At present the key for polycarboxylates application was to settle the compatibility between the water-reducing admixture and the cement and to keep the quality retention of this admixture.

海绵城市典型低影响开发设施水文性能的研究进展

海绵城市是未来城市雨洪管理的重要发展方向。低影响开发(LID)设施水文性能直接影响海绵城市建设成效。总结和探讨了典型LID设施的水文性能及其影响因素,分析了渗透系数、保水性和蒸散对径流总量控制、峰值流量控制、峰值延迟时间等的影响,并对未来研究方向进行展望。

硅丙乳液改性JS防水涂料的性能研究

以1∶9的质量比将3种不同型号的硅丙乳液(硅丙乳液1、硅丙乳液2、硅丙乳液3)分别与苯丙乳液复掺,然后与水泥等粉料按1∶1.5的质量比制成JS防水涂料并考察其性能。结果表明,与苯丙乳液制得的JS防水涂料相比,硅丙乳液1与苯丙乳液复掺制得的JS防水涂料拉伸强度和粘结强度最高,吸水率最低,但断裂伸长率会减小。优化复掺比例后发现,当硅丙乳液1的添加量为7.5%时,制得的JS防水涂料的拉伸强度、粘结强度、断裂伸长率和7 d吸水率分别为苯丙乳液制得的JS防水涂料的121%、125%、105%和84%,且符合GB/T 23445—2009标准的要求。

成胶型抑尘剂对煤体协同增润效应研究

为从源头控制煤矿开采过程中粉尘的产生,采用文献分析和试验的方法,筛选出润湿和保水性能较好的海藻酸钠单组分抑尘材料,并以此为基础制备出一种以海藻酸钠为主的煤层成胶增润型抑尘剂,其主要成分构成是质量分数为0.25%的海藻酸钠、0.15%的葡萄糖酸内酯、0.15%的乙二胺四乙酸二钠钙和0.1%的十二烷基硫酸钠,同时对制备的成胶型抑尘剂进行含水量、保水率、扫描电镜和比表面积及孔径测定。结果表明:该抑尘剂能够提高煤层的含水量和保水率,含水量比水为抑尘剂处理后的煤高近4倍,保水率比水处理的煤时间延长2倍以上;扫描电镜测试和比表面积和孔径测试表明,成胶型抑尘剂可增强材料对煤体的胶粘作用,且能够进入煤的内部孔隙在煤内外表面均成胶,有效地提高了保湿效果,实现从根本上控制煤体产尘。

大型露天建筑绿色施工扬尘污染治理方法研究

扬尘对人体和周边环境都具有很大的危害。为实现绿色施工,进行扬尘污染治理是十分必要的,因此研究一种大型露天建筑绿色施工扬尘污染治理方法。该研究从白果中提取纤维素并制备成纳米纤维素,再制成纳米纤维素抑尘剂。将纳米纤维素抑尘剂喷洒到地面,固化后实现扬尘污染治理。根据是否喷洒抑尘剂,设置实验组和对照度,实施吸湿保水性能测试和风蚀性能测试,结果表明:实验组吸湿强度更高、保水率更大,土样质量损失率、TSP浓度更大,说明纳米纤维素抑尘剂喷洒能够保持土样湿润性,增强了土样的抗风蚀性能,起到了扬尘污染治理的效果。

聚合物水泥防水涂料耐水性能影响因素研究

研究了聚合物乳液种类、聚合物乳液Tg值、水泥用量、填料种类和硅烷偶联剂用量对Ⅱ型JS防水涂料浸水后拉伸强度保持率、断裂伸长率和吸水率等指标的影响,结果表明,随着浸水时间的延长,JS防水涂料的拉伸强度、断裂伸长率都有不同程度的下降;选用Tg值为-15.3℃的丁苯乳液,水泥用量为50%,填料选用重钙,适量添加硅烷偶联剂制得的JS防水涂料耐水性能较佳。

重金属检测技术在水质分析中的应用

水质污染是当前环境领域的一大难题,尤其是由于工业化和城市化进程的加速,重金属污染引起了广泛关注。为了有效监测和控制水中重金属的浓度,各种先进的检测技术应运而生。本文首先介绍了水质中重金属常见的检测方法,如原子吸收光谱和荧光光谱,然后重点关注了近年来涌现的新型技术,包括电化学检测技术和生物检测技术。这些新技术不仅具有高灵敏度和选择性,而且具有实时监测和迅速响应的优势。

A Simple Mix Proportion Design Method Based on Frost Durability for Recycled High Performance Concrete Using Fully Coarse Recycled Aggregate

Durability design of recycled high performance concrete（RHPC） is fundamental for improving the use rate and level of concrete waste as coarse recycled aggregate（CRA）. We discussed a frostdurability-based mix proportion design method for RHPC using 100 % CRA and natural sand. Five groups of RHPC mixes with five strength grades（40, 50, 60, 70 and 80 MPa） were produced using CRA with four quality classes, and their workability, 28 d compressive strengths and frost resistances（measured by the compressive strength loss ratio and the relative dynamic modulus of elasticity） were tested. Relationships between the 28 d compressive strength, the frost resistance and the CRA quality characteristic parameter, water absorption, were then developed. The criterion of a CRA maximum water absorption limit value for RHPC was suggested, independent of its source and quality class. The results show that all RHPC mixes achieve the expected target workability, strength, and frost durability. The research results demonstrate that the application of the proposed method does not require trial testing prior to use.

Influences of Carboxyl Methyl Celluloseon Performances of Mortar

Carboxyl methyl cellulose （CMC） was mixed into mortar to improve the waterretention performance of mortar, the quality of floated coat of aerated concrete became better. The consistency and compression strength of mortar with CMC were studied. The water absorption was studied with the method of filter paper. The micro mechanism was researched with X-ray diffraction and scanning electron microscopy（SEM）. The experimental results show the water-holding performance of mortar with CMC is largely improved and it is better when the mixed amount is about 1.5%; the compression strength had a descending trend with the increase of CMC; CMC reacted with calcium hydroxide（CH） into the deposition of calcium carboxyl methyl cellulose.

Effect of Natural Zeolite on Performance of Sulfoaluminate Cement-based Planting Cementitious Material

This paper aimed to improve the water-retention performance and basic physical properties of sulfoaluminate cement（SAC）-based planting cementitious material. The effect of natural zeolite on the performance of SAC-based planting material was investigated. The water-retention performance, porosity, compressive strength, and alkalinity had been tested and TG-DSC analysis had been adopted in this paper. Experimental results showed that zeolite was effective to improve the water-retention capacity and 10%, 20% and 30% natural zeolite increased the pore volume of the hardened pastes by 10.6%, 26.0%, and 38.6%, especially pore size below 0.1 μm was increased by 9.7%, 26.2% and 17.5%. And 10% zeolite was beneficial to the compressive strengths of cementitious material and 1, 3, and 28 d compressive strength reached up to 35.9, 55.0, 80.3 MPa. Furthermore zeolite decreased the alkalinity of pore fluid of hardened cementitious material, while the addition of zeolite reached up to 30%, the alkalinity of pore fluid of hardened cementitious material decreased by 8.9%. Therefore zeolite was suitable for improving the performance of SAC-based planting cementitious material.

高保水矿用凝胶阻化材料的制备和性能研究

为防治煤自燃,以聚乙烯醇(PVA)、海藻酸钠(SA)和碱木质素(AL)为基体,硼砂(Borax)为交联剂,采用一锅法制备出一种新型高保水矿用凝胶阻化材料(PBSL)。以PVA,SA,AL,硼砂浓度(w(Borax))和加热时间为影响因素,设计了正交实验L16(4^(5)),结果表明,PVA,SA,AL分别为0.25、0.2、0.1 g,且w(Borax)=6%、加热时间为45 min时,材料的保水率和吸水率综合性能最佳,50℃加热30 h后保水率仍能达到38.52%,吸水率达到47.67%。通过分子结构分析,材料形成了硼酸酯键和氢键;阻化性能研究表明,PBSL凝胶阻化材料使煤样临界温度从80℃提高到100℃,200℃时材料阻化率高达55.28%,从而降低了煤的氧化活性。

堇青石基复相微晶玻璃的性能预测与组分优化

依据单纯形格子点设计,利用堇青石基质玻璃,低膨胀硼硅酸盐玻璃,熔融石英三种原料组分通过烧结法制备了堇青石基复相微晶玻璃,建立回归模型,并对其吸水率和热膨胀性能进行测试。结果表明:所建模型准确度高,可以准确地预测微晶玻璃的性能;在微晶玻璃单性能下优化时,通过指定性能可以确定原料组分;在双性能下优化时,通过指定的性能范围可以确定原料组分的区域。同理对于多性能,通过性能区域叠加,也可以确定原料组分的组成范围。在双性能优化的区域范围内,选择了一点进行验证实验,证明了实验的可靠性;该研究能给其他研究提供一个借鉴。

Design of Collagen-Based Hemostatic Material for Use in Plastic and Reconstructive Surgery

This study aims to develop collagen-based hemostatic materials. The sheet-shaped collagen sponge was manufactured by freeze-vacuum drying the aqueous solution of collagen (Col) and heat-denatured collagen (Col’) at a composition ratio of 2/1. The both sides or one side of sponge was treated with ultraviolet (UV) irradiation for 15 minutes to introduce intermolecular crosslinks between collagen molecules. The elution behavior of collagen sponge was investigated by immersing the sponge in water for a predetermined time and then by measuring the weight change. The double-sided UV-irradiated sponge showed very slow elution properties. On the other hand, the single-sided UV-irradiated sponge showed initially fast elution and subsequent very slow elution properties. Such initially fast elution of collagen molecules from the surface without UV-irradiation allows an adhesion of collagen sponge to the wound surface and results in hemostatic effect. In addition, the water absorption and retention properties of sponge were investigated by placing the hydrated sponge on a mesh for a predetermined time and then by measuring the weight change. The double-sided UV-irradiated sponge absorbed 81 times more water than own weight and showed a value of 45 times even after 7 days. The single-sided UV-irradiated sponge absorbed 80 times more water than own weight and showed a value of 39 times even after 7 days. The sponge with high water absorption and retention properties allows a wound healing effect because such sponge can absorb large amounts of blood plasma and exudates containing various cell growth factors. The double-sided UV-irradiated sponge is a good candidate for the wound dressing. On the other hand, the single-sided UV-irradiated sponge is a good candidate for the hemostatic material.

PVAL/肉桂醛/山梨酸钾复合薄膜的制备及性能

选取聚乙烯醇(PVAL)为成膜基材,添加不同配比的肉桂醛(CIN)和山梨酸钾(KS),采用流延法制备一种PVAL/CIN/KS复合薄膜,通过改变CIN的添加量来改善薄膜的热性能、力学性能、阻隔性能和耐水性能等。采用傅里叶变换红外光谱仪、差示扫描量热仪、万能力学试验机、紫外-可见分光光度计等对复合薄膜的性能及结构进行一系列的表征和分析。结果表明,随着CIN含量增加,复合薄膜的熔点有所下降,在CIN质量分数(PVAL质量的百分数)为40%时,熔点达到最小值为154.22℃。拉伸强度随CIN含量增加呈现出先增大后降低的趋势,断裂伸长率则逐渐提升,当CIN质量分数为20%时拉伸强度达到最大值,为12.84 MPa,相比于未添加CIN/KS复合物的薄膜而言,提高了79.08%,当CIN质量分数增加至30%时,薄膜的拉伸强度变为11.53 MPa,断裂伸长率从554.19%提升至596.48%。当CIN质量分数为30%时,薄膜表现出最佳的气体阻隔性,水蒸气透过系数达到最低,为1.04 g·mm/(m^(2)·h·kPa),吸水率趋于饱和状态,为78.71%,综合性能最佳。

废弃玻璃渣的功能化制备与吸水性能研究

随着人们对玻璃材料使用量的增加,产生了大量的废玻璃制品,其回收利用低,造成环境污染及资源浪费。通过以天然蛭石为造孔剂与玻璃复合,讨论质量和研磨时间对吸水性能的影响,吸附实验结果表明:蛭石的添加量为40wt%,研磨时间为6 min时,其吸附率达0.8 g/g^(-1),经过20次重复吸水循环使用后吸水仍保持率为97.5%,具有良好的重复吸水稳定性,这一结果为多孔玻璃应用于吸附领域提供了参考依据。

苏里格气田解水锁剂渗吸性能评价和影响因素分析

苏里格气田属于典型的“低孔、低渗、低压、低丰度”气藏。苏里格气田上古生界气层主要为岩屑砂岩和石英砂岩,胶结物中含量很高的黏土矿物主要为伊/蒙混层,孔径小、喉道窄,面孔率低,是典型的低孔低渗储集层,非均质性很强,且由于石英含量高,属于亲水储集层,表现为强水锁特征,很容易发生水锁伤害。主要研究苏里格气田气井水锁影响因素和解水锁剂性能评价,通过分析解水锁剂和岩心的基本物性参数,绘制不同影响因素下岩样的渗吸量、含水饱和度、渗吸速率曲线,并以此来评价解水锁剂性能;通过岩心流动实验,测定岩心浸泡解水锁剂前后的液测渗透率,分析解水锁剂的解水锁效果。

聚乙烯醇改性橡胶水泥基复合材料耐久性研究

为提升高寒地区混凝土坝的工作性能,通过毛细吸水试验、抗氯离子试验、冻融试验和碳化试验,研究聚乙烯醇(polyvinyl alcohol, PVA)改性废弃橡胶对水泥基复合材料耐久性能的影响,分析体积分数为0~30%的橡胶颗粒经质量分数为0.1%的PVA溶液改性前后水泥基复合材料耐久性的变化.结果显示,当橡胶体积分数增加到10%时,水泥基复合材料的毛细吸水性、抗氯离子渗透性、抗冻融能力以及抗碳化性能均得到了提升;加入PVA后,橡胶颗粒与水泥基体之间的黏结性增强,特别是橡胶体积分数为10%时,累计孔隙体积降低了28.8%,进一步提高了橡胶水泥基复合材料的耐久性能.研究可为橡胶混凝土在工程实际中的进一步应用提供新思路.

不同发泡倍率聚乙烯醇基缓冲包装材料性能

目的探究聚乙烯醇(PVA)基发泡材料的缓冲包装性能,为PVA基发泡材料应用于易渗出水溶性液体的产品包装提供一定的理论依据和实践经验。方法采用化学发泡法制备不同发泡倍率的PVA基发泡材料,研究其微观结构、吸水性能和不同条件下的缓冲性能。结果不同发泡倍率下,5种密度PVA基发泡材料均具有良好的吸水性和保水性,且吸水率越高,保水性越差。在干燥状态下,材料的质地较硬,且其缓冲性能随着发泡倍率的增大而减小,材料吸水后变得柔软且富有弹性,当吸水率达到58.0%后,材料的缓冲性能则急剧下降。结论经综合比较,密度为0.146g/cm^(3)的PVA基发泡材料具有良好的吸水性能、保水性能和缓冲性能,在材料的吸水率低于58.0%时,可满足易渗液体容器的锁水和缓冲包装需求。