余热驱动低温蒸馏海水淡化系统工艺流程及性能分析

针对以商品蒸汽作为热源的传统蒸馏法海水淡化造水成本较高的问题,结合沿海钢铁、石化等企业大量的余热无法找到合适利用途径的现状,提出余热驱动低温蒸馏工艺,最大限度地利用低品位余热,避免能源浪费及环境污染。文中提出两种利用工业低品位热水生产淡水的海水淡化工艺配置流程,通过建立海水淡化系统热力学模型,以淡水产量10000 m~3/d为例,比较造水比、传热面积等系统性能参数,分析废热水给水温度、回水温度、废热水流量对海水淡化产水量的影响。为利用低品位能源如太阳能、钢铁、石化行业废热水等过程余热进行海水淡化提供设计数据依据和理论支撑。     

水蒸气吸附/解吸海水淡化技术特点及优势

针对现有反渗透、多级闪蒸、多效蒸馏等传统海水淡化技术存在的热源温度要求高、产水率低、能耗和电耗高等问题,介绍了一种新型的海水淡化工艺和技术——水蒸气吸附/解吸海水淡化技术。该技术具有能量利用率高,所产淡水水质高,对驱动热源的适应性广,可利用太阳能、地热等可再生能源等优点,有利于技术推广和成果转化,是一种海水淡化领域的前沿技术,具有良好的节能效果、社会效益和海洋生态效益。     

低温多效蒸馏海水淡化水热电三联产系统经济性分析

对于凝汽式机组,提出采用低真空运行后的高温排汽作为低温多效蒸馏海水淡化的热源,实现水电联产.在此基础上,冬季利用一部分汽轮机排汽用于对热用户供暖.电厂在低真空运行模式下的热力计算采用矩阵法并基于弗留格尔公式进行变工况计算.低温多效蒸馏海水淡化系统的数学模型采用等温差法建立,并同时建立了制水成本的经济性计算模型.根据计算结果分析了低温多效蒸馏海水淡化系统的蒸发器效数、供热负荷、蒸发器传热系数和制水成本之间的关系,并得出了影响制水成本的主要因素及其敏感性分析.     

小型管式降膜太阳能海水蒸馏装置性能分析

为了利用分布式小型海水脱盐装置生产淡水,文章提出了一种新型管式降膜太阳能海水蒸馏装置,并分析了该装置的产水性能,以及进料海水盐度、进水流量等对该装置的产水速率、冷凝温度、排浓海水温度等的影响。研究结果表明:产水速率随着进料海水盐度的增加而减小,在运行温度为80℃的情况下,当进料海水盐度为3.5%时,产水速率为151.02 g/10 min,比进料海水盐度为10.5%时增加了20.33%;产水速率随着进水流量的减少而增加,在运行温度为80℃的情况下,当进水流量为0.44 kg/h时,产水速率为0.907 kg/h,比进水流量为0.68 kg/h时增加了21.42%;通过管式降膜太阳能海水蒸馏装置的模块化组合,可以满足用户不同的淡水需求量。     

一种回收蒸发潜热太阳能蒸馏装置的研究

对一种回收蒸发潜热的太阳能蒸馏装置进行了研究.结果表明,太阳辐照度、冷凝器冷却海水流量和蒸发器入口海水温度是影响系统性能的主要因素,当冷凝器冷却海水流量为45 l/h,蒸发器入口海水温度为75℃时,系统具有较大的淡水产量和合适的系统GOR值.     

一种回收蒸发潜热太阳能蒸馏装置的研究

对一种回收蒸发潜热的太阳能蒸馏装置进行了研究。结果表明，太阳辐照度、冷凝器冷却海水流量和蒸发器入口海水温度是影响系统性能的主要因素，当冷凝器冷却海水流量为４５ｌ／ｈ，蒸发器入口海水温度为７５℃时，系统具有较大的淡水产量和合适的系统ＧＯＲ值。     

船用蓄能式海水淡化装置研究

针对现有船舶海水淡化装置工况不稳定、主机低负荷工况工作时难以连续制取淡水的问题,设计了一种利用70℃主机缸套冷却水的余热作为热源,以海水作为冷源,利用热管和纳米蓄热材料组成的蓄热器,回收利用系统中大量低品位能量,使现有资源得到了更有效合理地配置,并解决了船舶淡水资源供给短缺的问题,达到了节能减排的目的。     

太阳能空气隙膜蒸馏系统实验研究

空气隙膜蒸馏是一种新的膜分离技术,它可以使用太阳能等低位热能作驱动力,用于海水、苦咸水的淡化处理,在淡化水制备方面具有极强的竞争力.文章介绍的空气隙膜蒸馏实验装置,采用太阳集热装置来加热进液,通过膜蒸馏获得纯净水.结合实验数据,文章给出了料液进口温度、流量、空气隙厚度等参数对于膜通量的影响和空气隙膜蒸馏系统热容腔内对流换热传热系数的经验公式.     

新型平板太阳能集热器海水淡化系统研究

海水淡化是利用海水脱盐生产淡水的技术和过程。多效蒸馏海水淡化原理是高温蒸汽或热水与海水进行热交换,海水被加热,蒸发出的水蒸气冷凝得到淡水,但其结垢和腐蚀问题比较严重。低温多效蒸馏是多效蒸馏技术的一种改进技术,操作温度较低,避免和减轻了海水对设备造成的腐蚀与结垢问题,     

降低吸附式制冷系统驱动热源温度的研究进展

吸附式制冷是一种环境友好的制冷方式,可以利用低品位热能提供冷量,因此具有重要的节能意义。目前,吸附式制冷技术在太阳能热利用、工业余热利用等中低温余热领域已有应用,但对低于60℃热源的利用实例较少。降低吸附式制冷系统所需的驱动热源温度是扩大吸附式制冷系统使用范围的重要手段。吸附式制冷系统所需驱动热源温度与系统循环方式、吸附剂性能等因素密切相关。从二级/多级吸附式制冷循环、表面酸性强度与孔结构等影响吸附剂再生温度方面阐述了降低吸附式制冷系统驱动热源温度技术的国内外研究现状。分析结果显示,多级循环吸附式制冷系统可以降低装置的驱动热源温度,但装置结构较为复杂;低再生温度吸附剂能够拓宽吸附式制冷装置的驱动热源温度范围,吸附剂的脱附温度与表面极性、酸性、孔结构等参数有关,对吸附剂进行改性,吸附剂极性弱、酸性低的表面特性有利于降低脱附温度。另外,还介绍了数据中心余热驱动的吸附式制冷技术。开展降低吸附式制冷系统驱动热源温度的研究为低温余热高效利用提供了技术参考。     

应用人工神经网络(ANN)分析热泵型海水淡化系统产水特性

利用人工神经网络来模拟仿真热泵型海水淡化系统的性能。以空气入口干球温度和湿球温度、预冷器进口冷却水温度、预冷器出口冷却水温度、海水喷淋温度作为输入参数,建立了海水淡化系统产水(淡水)模型。对建好的神经网络模型经训练学习后,用来模拟预测预冷器和蒸发器的产水值,并且与数值模拟产水值、实验产水值进行了比较,误差较小。表明利用人工神经网络(ANN)建立的热泵型海水淡化系统仿真模型取得了满意的结果。     

Second law analysis of reverse osmosis desalination plants: An alternative design using pressure retarded osmosis

A second law analysis of a reverse osmosis desalination plant is carried out using reliable seawater exergy formulation instead of a common model in literature that represents seawater as an ideal mixture of liquid water and solid sodium chloride. The analysis is performed using reverse osmosis desalination plant data and compared with results previously published using the ideal mixture model. It is demonstrated that the previous model has serious shortcomings, particularly with regard to calculation of the seawater flow exergy, the minimum work of separation, and the second law efficiency. The most up-to-date thermodynamic properties of seawater, as needed to conduct an exergy analysis, are given as correlations in this paper. From this new analysis, it is found that the studied reverse osmosis desalination plant has very low second law efficiency (<2%) even when using the available energy recovery systems. Therefore, an energy recovery system is proposed using the (PRO) pressure retarded osmotic method. The proposed alternative design has a second law efficiency of 20%, and the input power is reduced by 38% relative to original reverse osmosis system.     

多级鼓泡式加湿除湿型太阳能海水淡化装置研究

提出一种多级鼓泡式加湿除湿型海水淡化装置。该装置主要由多曲面太阳能聚光系统、加湿层和除湿层以及相应的泵和管路组成。经聚光器加热后的高温空气在风机驱动下分别进入加湿层和除湿层,热风穿过各级筛板及筛孔,产生气泡,增大了空气与水的接触面积,强化了传热传质过程。在不同天气下对装置进行实验研究,结果表明：在晴朗天气下,装置的太阳能利用率最高可达0.41,淡化装置效率最大可达1.23,最大产水速率为3.66 kg/h,全天产水量为17.08 kg;在非晴朗天气下,装置产水量为12.43 kg。     

Exergy study of hydrogen cogeneration and seawater desalination coupled to the HTR-PM nuclear reactor

This work presents a novel integration system of the high-temperature gas-cooled reactor-pebble bed module project to a hydrogen production process using the iodine-sulfur cycle in cogeneration with seawater desalination. The current approach includes a Rankine cycle, a sulfur-iodine thermochemical cycle for hydrogen production and a multi-stage flash desalination process. The use of a catalyst that allows the H₂SO₄ decomposition reaction to being carried out at temperatures compatible with the nuclear reactor project is considered. The residual heat from the acid decomposition reactions is used to desalinate seawater through the multi-stage flash process. A chemical process simulator is used to create a computational model that allows estimates of global and local efficiencies of the proposed flow diagram. Some operating parameters were sized, and their influence on the efficiency is also reported. The proposed model for the sulfur-iodine cycle can produce 0.41 kg/s of hydrogen with partial energy and exergetic efficiency of 37.35% and 38.64%. The desalination process can process 40.70 kg/s with energy and exergy efficiencies of 58.78% and 82.66%, respectively. The higher exergy destruction share is obtained in the heat exchangers (36.55%), chemical reactors (16.56%) and separators (12.80%). The global system showed efficiencies of 40.13% and 52.04%, respectively.     

Parametric analysis and optimization for a combined power and refrigeration cycle

A combined power and refrigeration cycle is proposed, which combines the Rankine cycle and the absorption refrigeration cycle. This combined cycle uses a binary ammonia–water mixture as the working fluid and produces both power output and refrigeration output simultaneously with only one heat source. A parametric analysis is conducted to evaluate the effects of thermodynamic parameters on the performance of the combined cycle. It is shown that heat source temperature, environment temperature, refrigeration temperature, turbine inlet pressure, turbine inlet temperature, and basic solution ammonia concentration have significant effects on the net power output, refrigeration output and exergy efficiency of the combined cycle. A parameter optimization is achieved by means of genetic algorithm to reach the maximum exergy efficiency. The optimized exergy efficiency is 43.06% under the given condition.     

Performance analysis of organic Rankine cycle based on location of heat transfer pinch point in evaporator

The location of heat transfer pinch point in evaporator is the base of determining operating parameters of organic Rankine cycle (ORC). The physical mathematical model seeking the location of pinch point is established, by which, the temperature variations both of heat source and working fluid with UA can be obtained. Taking heat source with inlet temperature of 160 °C as example, the matching potentials between heat source and working fluid are revealed for subcritical and supercritical cycles with the determined temperature difference of pinch point. Thermal efficiency, exergy efficiency, work output per unit area and maximum work outputs are compared and analyzed based on the locations of heat transfer pinch point either. The results indicate that supercritical ORC has a better performance in thermal efficiency, exergy efficiency and work output while outlet temperature of heat source is low. Otherwise, subcritical performs better. Small heat transfer coefficient results in low value of work output per unit area for supercritical ORC. Introduction of IHX may reduce the optimal evaporating pressure, which has a great influence on heat source outlet temperature and superheat degree. The analysis may benefit the selection of operating parameters and control strategy of ORC.     

Comparison of energy and exergy analysis of fossil plant,ground and air source heat pump building heating system

The energy and exergy flow for a space heating systems of a typical residential building of natural ventilation system with different heat generation plants have been modeled and compared. The aim of this comparison is to demonstrate which system leads to an efficient conversion and supply of energy/exergy within a building system.The analysis of a fossil plant heating system has been done with a typical building simulation software IDA–ICE. A zone model of a building with natural ventilation is considered and heat is being supplied by condensing boiler. The same zone model is applied for other cases of building heating systems where power generation plants are considered as ground and air source heat pumps at different operating conditions. Since there is no inbuilt simulation model for heat pumps in IDA–ICE, different COP curves of the earlier studies of heat pumps are taken into account for the evaluation of the heat pump input and output energy.The outcome of the energy and exergy flow analysis revealed that the ground source heat pump heating system is better than air source heat pump or conventional heating system. The realistic and efficient system in this study “ground source heat pump with condenser inlet temperature 30 °C and varying evaporator inlet temperature” has roughly 25% less demand of absolute primary energy and exergy whereas about 50% high overall primary coefficient of performance and overall primary exergy efficiency than base case (conventional system). The consequence of low absolute energy and exergy demands and high efficiencies lead to a sustainable building heating system.     

First and second law analysis of a new power and refrigeration thermodynamic cycle using a solar heat source

The first and second laws of thermodynamics were used to analyze a novel thermodynamic cycle proposed by Goswami in 1995 that uses an ammonia–water binary mixture as the working fluid, while producing both power and refrigeration simultaneously. The thermodynamic performance of the cycle was optimized for maximum second law efficiency using a commercially available optimization program. A maximum second law efficiency of 65.8% was obtained at a heat source temperature of 420 K. An exergy analysis was performed to study losses in different components of the cycle. It is seen that the largest contribution to cycle irreversibility comes from the absorber, with the rectifier and solution heat exchanger also contributing significantly. Irreversibility generation in the boiler is high at very low heat source temperatures, but drops at higher temperatures.     

S-CO2布雷顿循环太阳能电力淡水系统火用分析

设计一种使用S-CO₂布雷顿循环的太阳能电力淡水系统,对系统的工作原理和结构组成进行介绍,并对系统开展运行性能和火用分析。结果表明,设计工况下系统的输出电功率为233.8 MW,布雷顿循环效率为37.5%,淡水日产量为3981.6 t。增大太阳辐照度有利于提高系统的电力输出和总的能量效率。定工况下的火用分析结果表明,太阳塔集热器中的火用损最大,为303.99 MW,对应的火用效率为64.45%。海水淡化换热器的火用效率最低,且其火用损值也较大。随着太阳辐照度的增加,太阳塔集热器、海水淡化系统换热器和回热器内的火用损均有不同幅度的增加。因此,对于该S-CO₂布雷顿循环太阳能电力淡水系统的后续优化而言,应重点考虑改进这些部件的性能。     

Exergy based analysis of solar air heater having discrete V-down rib roughness on absorber plate

The artificially rib roughened solar air heaters perform thermally better than the conventional flat-plate solar air heater under same operating conditions. However, the artificial rib roughness leads to higher friction factor thereby increasing pumping power. The second law based exergy analysis is suitable for design of rib roughened solar air heaters as it incorporates quality of useful energy output and pumping power. The exergetic efficiency of a solar air heater having discrete V-down rib roughness is studied analytically and the results obtained are compared with that of a conventional flat-plate solar air heater. Flow Reynolds number and rib-roughness parameters, viz., relative roughness pitch, relative gap position, relative gap width, angle of attack and relative roughness height have combined effect on heat transfer as well as fluid friction. The exergy based criterion suggests use of the discrete V-down rib roughened solar air heater for the Reynolds number range normally used in solar air heaters. It was found that there exist optimum roughness parameters of the discrete V-down rib for a given Reynolds number (or temperature rise parameter) at which the exergetic efficiency is highest. Curves of optimum rib-roughness parameters are also plotted.