Multi-objective optimization of equipment capacity and heating network design for a centralized solar district heating system

Northwest China has abundant solar energy resources and a large demand for winter heating.Using solar energy for centralized heating is a clean and effective way to solve local heating problems.While present studies usually decoupled solar heating stations and the heating network in the optimization design of centralized solar heating systems,this study developed a joint multi-objective optimization model for the equipment capacity and the diameters of the heating network pipes of a centralized solar district heating system,using minimum total life cycle cost and CO_(2)emission of the system as the optimization objectives.Three typical cities in northwest China with different solar resource conditions(Lhasa,Xining,and Xi'an)were selected as cases for analysis.According to the results,the solar heating system designed using the method proposed in this study presents lower economic cost and higher environmental protection in comparison to separately optimizing the design of the solar heating station and the heating network.Furthermore,the solar fraction of the optimal systems are 90%,70%,and 31%for Lhasa,Xining,and Xi'an,and the minimum water supply temperatures are 55℃,50℃,and 65℃for an optimal economy and 55℃,45℃,and 45℃for optimal environmental protection,respectively.It was also established that the solar collector price has a greater impact on the equipment capacity of the solar heating station than the gas boiler price.

New Hybrid CHP System Integrating Solar Energy and Exhaust Heat Thermochemical Synergistic Conversion with Dual-Source Energy Storage

For the efficient use of solar and fuels and to improve the supply-demand matching performance in combined heat and power(CHP)systems,this paper proposes a hybrid solar/methanol energy system integrating solar/exhaust thermochemical and thermal energy storage.The proposed system includes parabolic trough solar collectors(PTSC),a thermochemical reactor,an internal combustion engine(ICE),and hybrid storage of thermal and chemical energy,which uses solar energy and methanol fuel as input and outputs power and heat.With methanol thermochemical decomposition reaction,mid-and-low temperature solar heat and exhaust heat are upgraded to chemical energy for efficient power generation.The thermal energy storage(TES)stores surplus thermal energy,acting as a backup source to produce heat without emitting CO_(2).Due to the energy storage,time-varying solar energy can be used steadily and efficiently;considerable supply-demand mismatches can be avoided,and the operational flexibility is improved.Under the design condition,the overall energy efficiency,exergy efficiency,and net solar-to-electric efficiency achieve 72.09%,37.65%,and 24.63%,respectively.The fuel saving rate(FSR)and the CO_(2) emission reduction(ER_(CO_(2)))achieve 32.97%and 25.33%,respectively.The research findings provide a promising approach for the efficient and flexible use of solar energy and fuels for combined heat and power.

Comprehensive Molten Salt Storage Shell and Supporting Structure Design and Analysis-Part I:A Conductive and Convective Theoretical Heat Transfer Analysis for Molten Salt Cylindrical Shells at 565℃ and 700℃

In this paper a full theoretical thermal analysis of a large molten salt container,80-foot in diameter and 46-foot high,including a four-foot elliptic shell roof,is presented for two temperatures,the standard 565℃ and a futuristic 700℃,which substantially improves the efficiency of the molten salt containers through the use of a highly stable chloride salt called SS700(SaltStream 700).The theoretical analysis includes conductive and convective heat transfer analysis in the steel container,elliptic roof shell,the fiberglass insulation,and firebrick insulation,and includes thermal insulation designs to safeguard against energy losses at high temperatures.The underlying soil and the high temperature concrete foundation were analyzed theoretically using conductive heat transfer,however the area surrounding the soil surface around the bottom of the molten salt storage tank had convective heat transfer analysis included.The final designs presented in this paper seek to limit heat losses to a maximum of 250 W/m^(2) while being able to operate at a minimum external ambient temperature of-10℃,which determines the thicknesses of the fiberglass and firebrick insulation.

Comprehensive Molten Salt Storage Shell and Supporting Structure Design and Analysis-Part II:A Conductive and Convective Numerical Finite Element Heat Transfer Analysis for Molten Salt Cylindrical Shells at 700℃,and Comparison with Theoretical Analysis

In this paper a finite element thermal analysis model-using COMSOL-of a large molten salt container,80-foot in diameter and 46-foot high that includes a four-foot elliptic shell roof,is presented for a futuristic 700℃ design,which uses a highly stable chloride salt called SS700(SaltStream 700)that improves the efficiency of the tank when compared to the traditional 565℃.The FEA(finite element analysis)includes conductive and convective heat transfer analysis in the steel container,elliptic roof shell,the fiberglass insulation,and firebrick insulation,and includes thermal insulation designs to safeguard against energy losses at high temperatures.The underlying soil and the high temperature concrete foundation were analyzed by finite element using conductive heat transfer,however the area surrounding the soil surface around the bottom of the MS storage tank had convective heat transfer analysis included.The finite elements analyses presented are to verify the final fiberglass and firebrick insulation designs,which seeks to limit heat losses to a maximum of 250 W/m^(2) while being able to operate at a minimum external ambient temperature of-10℃.These results are also compared to previously calculated theoretical results.

基于场协同理论的热空气吹掠型太阳能蒸馏器对流传热性能优化分析

以热空气吹掠型太阳能蒸馏器为研究对象,利用数值模拟结果和均匀设计法分析蒸馏器内流动与传热场协同角的变化规律和影响因素。结果表明,影响场协同角的主要因素是热空气进口速度,热空气进口温度和水温的影响不显著。在蒸馏水温30~70℃、进口空气温度40~90℃,进口空气速度为8 m/s时平均传热场协同角最小,为73.14°,传热系数最大,可达到同等条件下自然对流传热系数的4倍。

双层相变材料复合水箱蓄热特性研究

以双层相变材料复合水箱为研究对象,通过数值模拟和实验研究的方法,对该水箱的蓄热特性进行模拟分析与实验验证,对比分析单、双层相变材料复合水箱的热特性,探究双层相变材料位置对复合水箱蓄热特性的影响规律。研究结果表明,与单层相变材料复合水箱相比,双层相变材料复合水箱的热分层更好,蓄热能力得到提升,双层相变材料复合水箱较普通水箱的蓄热量提高9.7%。双层相变材料距离进出水口位置较远时,相变材料完成熔化的时间更接近,更有利于蓄热水箱的热分层。

高原宾馆建筑电-热-氧联供系统容量优化配置

以青海省祁连县某宾馆为案例展开分析,建立以系统最小费用年值为优化目标的高原宾馆建筑电-热-氧联供系统容量配置优化模型,并采用遗传算法求解以得到系统的最优容量配置。结果表明:与常规电-热联供系统相比,电-热-氧联供系统使电网供电比例由76.9%降低至29.8%;电-热-氧联供系统的费用年值比常规电-热联供系统减少1.2%,其中系统投资年值增加4.1%,系统年运行费用减少5.3%;电-热-氧联供系统的费用年值受购氧价格影响最大,当购氧价格为8元/Nm^(3)以上时,电-热-氧联供系统比常规电-热联供系统更具经济优势。

建筑节能设计Low-E玻璃窗的遮阳参数取值分析

节能外窗属于精密工业制品,也是建筑工程外围护结构的重要组成部分。为能降低房间内的夏季太阳得热,工程中通常采用低辐射Low-E玻璃外窗,但由于国家及各地区的技术规范对Low-E玻璃窗的参数取值不尽相同、审图机构的把握尺度不一、门窗厂家的加工技术水平参差不齐,为能解决Low-E玻璃外窗的遮阳参数取值和选型困难的问题,达到概念清晰、数据可靠、便于实施的目的,文中采用公式计算和查表对比的方法,对规范的遮阳参数概念作补充说明,同时结合江苏某住宅项目的工程实践,给出Low-E玻璃窗遮阳参数的取值原则和建议,并认为一般Low-E玻璃的自遮阳系数取值最高不应超过0.60。

太阳能吸收式空调及供热系统的设计和性能

一套太阳能吸收式空调及供热综合系统已在山东省乳山市建成。该系统由热管式真空管集热器、溴化锂吸收式制冷机、储水箱、循环泵、冷却塔、空调箱、辅助燃油锅炉和自动控制系统等几部分组成 ,具有夏季制冷、冬季供热和全年提供生活用热水等功能。太阳能集热器总采光面积 5 40m2 ,制冷、供热功率 10 0kW ,空调、采暖建筑面积 10 0 0m2 ,供生活用热水量 32m3 /d。文中着重介绍了系统的设计特点和测试性能。

生物质能-太阳能互补供热系统优化设计

为了提高生物质能-太阳能互补供热系统的经济效益,该文从经济性角度对系统的主要参数进行优化设计,提出了一种生物质能-太阳能互补供热系统设计方案,建立了系统的经济分析模型,并采用线性规划的方法进行优化,并以北京地区一供热面积为200m2的办公楼为例进行了优化。结果表明,建立的经济分析模型可用,其中,太阳能集热器的价格、生物质颗粒燃料的价格、蓄热水箱的价格、生物质颗粒燃烧器的价格对系统中各部分参数的优化结果有影响,且影响程度依次降低。这可为今后生物质能-太阳能互补供热系统的设计提供参考。

太阳能与发电余热复合沼气增温系统设计

为了实现大中型沼气工程在北方寒冷地区的应用推广。该文针对北方寒冷气候特点,以哈尔滨双城市沼气工程为例构建了1套太阳能—发电余热中温厌氧发酵增温系统,阐述了该增温系统的设计原理,并对沼气发酵热负荷、发电机组余热回收利用率、太阳能集热装置热效率等关键参数进行了理论计算。计算得出该沼气工程全年平均每日热量的损失为6659.2 MJ,太阳能—发电余热中温厌氧发酵增温系统全年平均每日集热量为7017.6 MJ。通过对增温效果与该工程的热量损失进行对比,表明12、1、2月份系统需沼气发电机组额外提供372.2、369.4、208.3 kWh电量增温,其余月份系统可以实现发酵工程每日热量损失的补充,保证该工程的稳定运行。在8月份对示范工程的一次发酵罐体进行了增温效果测试,表明该增温系统在28 d左右可将该发酵罐内物料温度提升到中温发酵水平。该文为北方寒冷地区大中型沼气增温保温设备的配套建设提供参考。

一种全新型太阳能供热与制冷联合循环复合系统──Ⅰ.系统构造思想

提出一种利用太阳能作为驱动热源的固体吸附式制冷与供热联合循环方法，描述了太阳能制冷与供热联合循环的工作原理，并对循环装置内各子系统部件的热力循环过程和能量转化过程作了理论分析与计算说明。采用该联合循环装置，可实现用同一集热器白天加热的热水供夜间使用。

THE TEKOA BOYS’HOME A Melding of Vision,Functionality,and Sustainability

INTRODUCTION Community Housing Partners(CHP)is a 501(c)(3)community development corporation that serves the needs of low-income and low-wealth individuals and families in the southeast.CHP’s mission is to create affordable,green,sustainable housing opportunities and services for the people and communities they serve.Since 1975,CHP has served over 206,000 people,including the elderly,women and children in transition,formerly homeless people,single female heads-of-household.

采用热管冷却技术的太阳能光伏电–热一体化系统性能分析

太阳能光伏电–热(photovoltaic-thermal,PV-T)一体化系统将光伏组件与太阳能热利用系统组合在一起,具有较高的太阳能综合利用效率。针对热管具有高效传热和均温性能的特点,提出一种采用热管冷却技术的太阳能光伏电-热一体化系统;基于光伏电池板传热过程特点及换热器的传热有效度——传热单元数(ε-NTU)法,对热管式PV-T系统的电池板温度、冷却流体出口温度以及系统电效率和热效率等热电转换性能进行了理论分析和计算。结果表明,热管式PV-T系统的电池温度变化幅度在2.5℃以内,系统电效率和热效率分别达到6.99%～7.46%和51.0%～63.2%。该文提出的理论方法为研究热管式PV-T系统热电转换性能提供了一种新的途径,可用来分析和讨论相关参数对热管式PV-T系统性能的影响。

新型PV/T太阳能利用复合系统的实验研究

为提高PV/T系统太阳能利用率,同时获得可利用的热水和电力,将铝合金背板型单晶硅光伏组件和自行设计制作的不锈钢扁盒式集热板相结合,用导热硅胶加以粘接制成新型光伏光热一体化(PV/T)复合系统,该系统实现了光伏组件与集热板之间良好的粘接性、绝缘性和热传导,并在昆明地区对系统进行测试,分析了系统在不同水箱水容量及不同天气工况下运行的光电光热性能。结果表明,系统在75kg水箱水容量(m)晴天工况下运行效率更高,系统的平均电效率、热效率、综合效率及综合性能效率分别在14%、37%、51%、70.72%左右,与系统在50kg水箱水容量晴天或75kg水箱水容量多云工况下运行相比,综合性能效率约提高了11.86%或2.09%。与独立的光热或光伏系统相比,具有占地面积小、太阳能利用率高、更经济等优势。

太阳能空调及供热综合系统

结合建于山东的一个工程实例 ,介绍了太阳能吸收式空调及供热综合系统的构成、设计特点和主要性能 。

一种新型全铝扁盒式PV/T热水系统

将单晶硅光伏电池与全铝扁盒式太阳能热水器集热板通过特殊工艺粘结起来,制成了一套自然循环式光伏光热一体化(PV/T)系统,在利用太阳能发电的同时提供热水。于04年7月-10月在合肥地区进行了室外实验,测试并讨论了该系统以不同水量和不同初始水温运行时的光电光热性能。结果表明,当m/Ac>80kg/m2时,这种PV/T热水系统的发电效率在10.15%左右,热效率在50%左右,光电光热总效率可以达到60%左右,光电光热综合性能效率可以达到70%左右。相对于单纯的光伏系统或自然循环式太阳能热水系统,这种PV/T热水系统具有占地面积小、综合效率高等优点。

风-光复合发电系统的优化设计

文章介绍风 -光复合发电系统优化设计的一般数学模型 ,即以系统投资最小为目标 ,系统性能指标为约束 ,寻找风力发电机、光伏阵列、蓄电池、柴油机、逆变器和负载之间的最佳匹配功率及系统电能的最优管理及控制策略 ,运用该模型对实例进行计算 ,结果表明 ,风 -光复合发电系统的设计绝不是独立光伏发电系统和独立风力发电系统的简单拼凑 ,风 -光复合发电系统与独立光伏系统的优化设计规律存在较大的差异 ,其设计规律值得进一步深入研究。

新型太阳能连续型固体吸附制冷及供热复合机设计及性能模拟

该文提出了一种新型的太阳能连续型固体吸附制冷及供热复合机的设计方案 ,从理论上描述了该复合机的热力循环过程 ,并在正常工况下对该复合机进行了性能模拟分析。研究表明 :采用该种设计方案 ,复合系统能连续制冷 ,对于单一复合吸附床系统 ,在日辐射量为 2 1 6MJ,平均环境温度为 2 9 9℃ ,蒸发温度为 5℃ ,上床集热效率 η为 6 0 % ,下床与环境的换热系数α为 2W / (m2 ·K)的工况下 ,白天中能提供 4 7 8℃的热水 30kg ,系统平均制冷COPcooling为 0 18,平均供热COPheating为 0 34,吸附剂持续平均制冷功率SCPa 为 17 6W /kg ,集热面积持续平均制冷功率SCPc 为 87 8W /m2 ,集热面积持续平均供热功率SHPc 为 16 5 9W /m2 ;晚上每千克吸附剂制冷量为 0 2 6MJ ,每平方米集热面积制冷量为 1

太阳能与压缩空气耦合储能的燃气轮机CCHP系统特性

针对燃气轮机冷热电联产系统在"以热定电"运行方式下可能造成的电能过剩和部分负荷时效率不高等问题,该文提出一种太阳能与压缩空气耦合储能(solar andcompressed air energy storage,S-CAES)的燃气轮机冷热电联产系统。通过燃气轮机冷热电联产系统典型变工况模型和储能系统的Aspen Plus分析模型,获得S-CAES燃气轮机冷热电联产系统的变工况特性;讨论了各子系统的变工况特性和耦合系统在不同储能率下的运行性能,比较了储能系统释气流量调节与空气透平入口温度调节两种调节方式对系统性能的影响。将S-CAES燃气轮机冷热电联产系统用于华南地区某宾馆建筑进行案例分析,结果表明:与无储能燃气轮机冷热电联产系统相比,在夏季、过渡季、冬季典型日,该系统每天分别节约能量16.57、15.94、11.87GJ;平均能量利用率分别提高5.68%、7.88%和4.69%。