新型热源塔溶液再生系统非稳态特性分析与实验研究

针对热源塔冬季运行时存在的吸湿问题,构建了一种新型热源塔溶液再生系统并对其进行实验测试。考虑到系统在初始运行时需要建立平衡的温度场且系统运行时存在溶液不断变浓的现象,对该溶液再生系统启动时的非稳态特性进行了研究,获取了各运行参数随初始运行次数的变化规律,同时对不同浓度下各运行参数变化规律进行了实验分析。实验结果表明:初始开机运行后,随着运行次数的增多,在总运行水量保持不变的情况下,单次运行所需电量呈下降趋势,冷凝水量呈上升趋势,最终系统趋于稳定。随着溶液浓度的变化,系统再生效率存在先增加后降低的趋势,当溶液浓度达到18.5%时出现最佳值,此时再生效率为4.28 kg/(kW·h),再生速率为749 kg/d,再生百分比为14%。该装置将溶液的真空沸腾过程和冷凝过程融合在一起,系统能耗大大降低,具有较好的节能效果。     

新型热源塔溶液再生系统性能优化分析与实验研究

针对热源塔热泵系统冬季运行时存在的溶液稀释问题,提出了一种基于真空沸腾冷凝的新型热源塔溶液再生系统,并构建了相应的实验台。实验测试结果表明：随着溶液浓度的增加,溶液再生速率和再生效率存在先增加后降低的趋势,在乙二醇质量浓度为26%时达到最大;系统真空压力的增加可以极大提高溶液再生效率和再生速率,但其运行可靠性受到影响;进口溶液温度在36℃且电加热出口阀门开启时间为12 s时存在溶液再生效率的最大值。该溶液浓缩装置正常运行时溶液再生效率可达到3.40 kg/（kW·h）以上,溶液再生速率可达到550 kg/d,与传统的溶液再生相比,具有很好的节能性。     

新型热源塔溶液再生系统性能优化分析与实验研究

针对热源塔热泵系统冬季运行时存在的溶液稀释问题,提出了一种基于真空沸腾冷凝的新型热源塔溶液再生系统,并构建了相应的实验台。实验测试结果表明:随着溶液浓度的增加,溶液再生速率和再生效率存在先增加后降低的趋势,在乙二醇质量浓度为26%时达到最大;系统真空压力的增加可以极大提高溶液再生效率和再生速率,但其运行可靠性受到影响;进口溶液温度在36℃且电加热出口阀门开启时间为12 s时存在溶液再生效率的最大值。该溶液浓缩装置正常运行时溶液再生效率可达到3.40 kg/(k W·h)以上,溶液再生速率可达到550 kg/d,与传统的溶液再生相比,具有很好的节能性。     

基于空气能量回收的热源塔溶液再生系统节能性分析

对热源塔热泵系统进行了分析,指出了其溶液在冬季运行时存在再生问题.考虑到热源塔溶液吸湿性不强的特点,提出了一种基于空气能量回收的热源塔溶液再生装置,并对该系统再生性能进行了理论分析.对压缩机、换热器、节流阀、溶液再生器等各个系统部件建立了数学模型,并对整个溶液再生系统进行了模拟计算,计算结果表明:随着冷凝器进口溶液温度...     

无填料热源塔吸热效率实验

建立无填料热源塔热泵系统实验平台,研究不同进风位置、喷嘴位置、室外空气干球温度、相对湿度、风量、溶液入口温度下无填料热源塔吸热效率的变化规律。结果表明：进风位置和喷嘴位置对热源塔的吸热效率会产生影响,下喷式无填料热源塔吸热效率高于上喷式无填料热源塔;干球温度与吸热效率无明显相关性,但干球温度升高,热源塔从空气中吸收的总热量增加;相对湿度和风量升高,吸热效率提高;溶液入口温度升高,热源塔的吸热效率明显提高。与其他参数相比,溶液入口温度对热源塔的吸热效率影响最大。     

无填料热源塔吸热效率实验

建立无填料热源塔热泵系统实验平台,研究不同进风位置、喷嘴位置、室外空气干球温度、相对湿度、风量、溶液入口温度下无填料热源塔吸热效率的变化规律。结果表明:进风位置和喷嘴位置对热源塔的吸热效率会产生影响,下喷式无填料热源塔吸热效率高于上喷式无填料热源塔;干球温度与吸热效率无明显相关性,但干球温度升高,热源塔从空气中吸收的总热量增加;相对湿度和风量升高,吸热效率提高;溶液入口温度升高,热源塔的吸热效率明显提高。与其他参数相比,溶液入口温度对热源塔的吸热效率影响最大。     

闭式热源塔运行参数对热泵系统性能的影响

热源塔风机和防冻溶液循环泵是热源塔热泵系统中除压缩机外的主要耗电设备。通过改变热源塔风机和防冻溶液循环泵的工作频率,实验研究了冬季制热工况下闭式热源塔运行参数对热源塔吸热量和热泵系统性能的影响,研究结果表明,热源塔风机频率降低导致热源塔吸热量、系统制热量和热泵机组COP下降,但使系统能效比增大;热源塔吸热量随循环泵频率的增加先升高后降低并在25 Hz时达最大值,系统制热量同样随循环泵频率的增加先升高后降低,且随着风机频率的增大,制热量最大值对应的循环泵频率由35 Hz变为25 Hz;同时循环泵频率增加使热泵机组COP增加,但系统能效比减小;循环泵和风机频率均在15 Hz时,压缩机压缩比增大,压缩机效率低;系统制热量最高超过14.30 kW,热泵机组平均COP最高为3.31,系统平均能效比最高可达2.37。     

不同工况下除湿溶液再生的模拟与实验

建立了LiCl溶液再生过程的数学模型,通过模拟分析,得到了溶液再生量、溶液温度和溶液浓度随时间的变化规律。以平均再生量为评价指标,对LiCl溶液的再生性能进行了实验研究。分析了热源温度、溶液浓度、溶液初始温度、再生压力和冷水温度5个因素分别对溶液再生性能的影响规律。实验结果表明:溶液浓度和再生压力对溶液再生性能影响显著,冷水温度对溶液再生性能的影响最小。在设定的标准工况下,再生压力为4kPa、溶液中LiCl质量分数从28%增大到34%时,平均再生量由20.45g/(m²·s)减小至7.44g/(m²·s);再生压力从4kPa升高至10kPa时,平均再生量由15.33g/(m²·s)降低至1.92g/(m²·s)。最后,以溶液温度和溶液浓度作为对比目标参数将模拟结果和实验结果进行了对比分析,结果表明,实验值与模拟值符合较好。     

基于热源塔的热泵系统构建与试验

为解决水冷冷水机组冬季闲置和空气源热泵冬季制热存在的结霜问题,构建了一种基于热源塔的热泵系统。详细分析了热源塔热泵系统的构成和工作过程,依据所建立的热源塔热泵试验装置进行了不同热源塔溶液进出口温差的制热试验。结果表明:热泵制热量和COP都随着热源塔溶液进出口温差的增大而减小,而压缩机的耗功变化较小,空气与蒸发温度间的温差随之增大而增加;当环境温度为-1.2℃,热源塔溶液进出口温差从1.5℃增大到3℃时,热泵制热COP由3.02降为2.72,空气与蒸发温度的温差由7.64℃增大至11.96℃。整个实验过程中系统运行稳定可靠,避免了空气源热泵的结霜问题,表明热源塔热泵是一种非常具有前景的冷热源方案。     

内热型超声雾化溶液再生系统最优内热量的研究

基于质量守恒、能量守恒定律，建立了内热型超声雾化溶液再生系统（IH-UARS）的再生性能预测模型并进行了充分的实验验证，通过研究不同内热量下IH-UARS的再生性能及其变化规律，寻求系统所需的最佳内热量并明确其可能的影响因素。结果表明：IH-UARS系统存在最优的内热量范围，使其再生系统性能最佳；所需最优内热量随着再生溶液流量增大呈显著的对数增长，但受空气流量的影响较弱；在该研究中的标准工况下，IH-UARS所需最优内热量约为275~350 W。此外研究发现：内热量的增长有益于促进初始浓度较高的溶液进一步浓缩再生，如当IH-UARS中内热量增至800 W时，其初始浓度为36%的溶液比24%的溶液浓度增量指标改善幅度高37%。研究所得结果可对提高溶液再生性能及经济性提供积极参考。     

Review: Parametric Study on the Performance of Progressive Cryoconcentration System

Progressive cryoconcentration (PC) is gaining acceptance in solution concentration process as it could provide an easy separation and ice purification with relatively low energy. In fact, the advantages of PC process as compared to the other concentration methods have led the growth of related studies that aim to provide the best system or condition for the separation process involved. Apart from the provision of appropriate equipment, the PC process should also be conducted at its optimum conditions of operating parameters involved, which could give the highest separation efficiency. Hence, relationship between the parameters, which covers both manipulated and determinant parameters should be studied first. This review summarizes the previous conducted studies on the effect of various operating parameters on the PC performance, which includes effect of coolant temperature, solution flowrate, initial solution concentration, freezing time, ice crystal front growth rate, and stirring rate.     

New kinetic model for polymerization process of nylon 66 salt solution based on functional group non-isoactivity

The polymerization process of nylon 66 salt solution is a dynamically controlled process. Based on the assumption of unequal activity of functional carboxyl and amido groups, a new nylon 66 salt solution polymerization kinetic model was established by introducing the nylon salt dehydration reaction to the acid-catalyzed third-order reaction kinetic model and fitted to obtain the corresponding key kinetic parameters. The fitted salt dehydration reaction rate constant was 8.17×10^-3 kg?mol^-1?h^-1, while the activation energy was 19859 cal?mol^-1, respectively. Compared with Mallon model, the new developed model has a better fitting effect and can accurately predict the change of the polymerization process in a wider range of temperature and water content. Simulation results showed that salt dehydration reaction has an important effect on the polymerization process and the polymerization efficiency was relatively lower with higher concentration of nylon salt, especially under low temperature and high water content. Appropriately increase the reaction temperature or reduce the initial water content can accelerate the nylon salt dehydration reaction, thereby increasing the polymerization reaction efficiency. New nylon salt polymerization kinetics modeling method is not only applicable to nylon 66, but also to nylon 1212 and other salt solution polymerization systems.     

基于官能团非等活性假设的尼龙66盐溶液聚合动力学模型

尼龙66盐溶液聚合过程属于动力学控制过程。基于官能团非等活性假设，在Mallon酸催化3阶反应动力学模型基础上，引入尼龙盐脱水反应，建立了新的尼龙66盐溶液聚合反应动力学模型，拟合得到了关键反应动力学模型参数，其中盐脱水反应速率常数为8.17×10^-3 kg?mol^-1?h^-1、活化能为19859 cal?mol^-1。与Mallon模型相比，新模型拟合效果更优，可在更宽的温度和水含量范围内准确预测聚合过程的变化。模拟仿真发现，盐脱水反应对聚合过程有重要影响，低温和高水含量下尼龙盐浓度高，聚合效率低；适当提高反应温度或降低初始水含量可以加快尼龙盐脱水反应，从而提高聚合反应效率。新的尼龙盐聚合动力学建模方法不仅适用于尼龙66，也可应用于尼龙1212等盐溶液聚合体系。     

沸石去除水中二价铁的研究

研究沸石吸附柱去除地下水中二价铁的效果及影响因素。首先采用模拟地下水进行动态试验,其结果表明:水中二价铁离子初始浓度、吸附柱高度、进水流速等对二价铁交换容量均有不同程度的影响;然后采用盐酸逆流再生失效沸石,以再生效率和再生酸耗为衡量指标,考察了再生液浓度、再生液流速和再生时间对再生效果的影响;最后采用模拟试验中所得最佳运行参数,去除实际地下水中的二价铁离子,取得了较为理想的去除效果。     

氯化钙溶液喷雾闪蒸再生特性模拟及试验分析

燃煤电厂排放的烟气中含有大量水蒸气，氯化钙溶液循环除湿技术具有较好的除湿潜力。为了研究吸湿后的氯化钙溶液的再生性能，使用Matlab软件对液滴闪蒸过程进行了数值模拟，并搭建了氯化钙溶液喷雾闪蒸试验台。考察了闪蒸压力，溶液初始温度、浓度、溶液流量等因素对氯化钙溶液再生量的影响。试验结果表明了数学模型的准确性；溶液表面蒸气压和再生压力的差值以及溶液过热度是影响再生量的关键因素；闪蒸出口水蒸气经冷凝后Cl^–含量不足0.2 mg/L。浓度为35%的溶液在再生温度为60℃、再生压力为10 kPa、流量为0.2 m³/h的情况下，可以实现5 kg/h以上的水分回收量。     

Phosphorus Removal from Continuous Phosphate-Contaminated Water by Electrocoagulation using Aluminum and Iron Plates Alternately as Electrodes

The objective of this study was to investigate the effects of the main parameters on phosphate removal from continuous phosphate-contaminated water by electrocoagulation based on removal rate and system energy consumption. In the experiment, aluminum and iron plates were used as alternate electrodes and experiment parameters included initial phosphate concentration, current density, flow rate, and initial pH. The results indicated that increases of initial phosphate concentration and flow rate had reduced removal rate and energy consumption. Removal rate and system energy consumption increased by increasing current density. The maximum removal efficiency of 90% was obtained at flow rate 40 mL/min. The minimum energy consumption was 0.165 kWh/m³ at flow rate 100 mL/min. With the increase of initial pH from 4 to 8, the removal rate increased and energy consumption decreased. When the pH was above 8, the removal rate decreased and energy consumption increased. The maximum removal efficiency of 92% and minimum energy consumption of 0.191 kWh/m³ were obtained at pH 8.     

Separation of Water and Nitric Acid with Porous Hydrophobic Membrane by Air Gap Membrane Distillation (AGMD)

Abstract

This study investigates the effect of operation parameters on the separation of nitric acid‐water mixture using air gap membrane distillation (AGMD). Porous hydrophobic PTFE membrane was used. The performance was evaluated based on the permeate flux and the nitric acid selectivity. Operating parameters such as feed solution temperature, feed concentration, flow rate, and air gap width were varied. Nitric acid selectivity was found to increase with the increase in feed solution temperature, feed concentration, flow rate, and air gap width. Permeate flux increased, when the feed temperature and the flow rate were increased. The effect of recirculation of the feed solution was also studied. With the recirculation mode, at different initial solution volumes, it was observed that the nitric acid concentration in the feed and the permeate, increased. The rate of flux decline was greater, when the initial feed solution volume was lower.     

Rapid regeneration of chelated iron desulfurization solution using electrochemical reactor with rotating cylindrical electrodes简

A new electrochemical reactor with rotating cylindrical electrodes was designed and used to increase the regeneration efficiency of chelated iron desulfurization solution. The influence of operating parameters, such as the rotation speed of electrode, voltage, and inlet air and liquid flow rates, on the regeneration rate was investigated. Compared with the traditional tank-type reactor, the regeneration rate with the new electrochemical reactor was in- creased significantly. Under the optimum conditions, the regeneration rate was increased from 45.3% to 84.8%. Experimental results of continuous operation indicated that the new electrochemical regeneration method had some merits including higher regeneration efficiency, smaller equipment size and good stability in operation.