Water, Air Emissions, and Cost Impacts of Air-Cooled Microturbines for Combined Cooling, Heating, and Power Systems： A Case Study in the Atlanta Region

The increasing pace of urbanization means that cities and global organizations are looking for ways to increase energy efficiency and reduce emissions. Combined cooling, heating, and power （CCHP） systems have the potential to improve the energy generation efficiency of a city or urban region by providing energy for heating, cooling, and electricity simultaneously. The purpose of this study is to estimate the water consumption for energy generation use, carbon dioxide （CO2） and NOx emissions, and economic impact of implementing CCHP systems for five generic building types within the Atlanta metropolitan region, under various operational scenarios following the building thermal （heating and cooling） demands. Operating the CCHP system to follow the hourly thermal demand reduces CO2 emissions for most building types both with and without net metering. The system can be economically beneficial for all building types depending on the price of natural gas, the implementation of net metering, and the cost structure assumed for the CCHP system. The greatest reduction in water consumption for energy production and NOx emissions occurs when there is net metering and when the system is operated to meet the maximum yearly thermal demand, although this scenario also results in an increase in greenhouse gas emissions and, in some cases, cost. CCHP systems are more economical for medium office, large office, and multifamilv residential buildings.

Integration of Low-level Waste Heat Recovery and Liquefied Nature Gas Cold Energy Utilization

Two novel thermal cycles based on Brayton cycle and Rankine cycle are proposed, respectively, which integrate the recovery of low-level waste heat and Liquefied Nature Gas （LNG） cold energy utilization for power generation. Cascade utilization of energy is realized in the two thermal cycles, where low-level waste heat,low-temperature exergy and pressure exergy of LNG are utilized efficiently through the system synthesis. The simulations are carried out using the commercial Aspen Plus 10.2, and the results are analyzed. Compared with the conventional Brayton cycle and Rankine cycle, the two novel cycles bring 60.94% and 60% in exergy efficiency, respectively and 53.08% and 52.31% in thermal efficiency, respectively.

Optimal Scheduling Method of Cogeneration System with Heat Storage Device Based on Memetic Algorithm

Electric-heat coupling characteristics of a cogeneration system and the operating mode of fixing electricity with heat are the main reasons for wind abandonment during the heating season in the Three North area.To improve the wind-power absorption capacity and operating economy of the system,the structure of the system is improved by adding a heat storage device and an electric boiler.First,aiming at the minimum operating cost of the system,the optimal scheduling model of the cogeneration system,including a heat storage device and electric boiler,is constructed.Second,according to the characteristics of the problem,a cultural gene algorithm program is compiled to simulate the calculation example.Finally,through the system improvement,the comparison between the conditions before and after and the simulation solutions of similar algorithms prove the effectiveness of the proposed scheme.The simulation results show that adding the heat storage device and electric boiler to the scheduling optimization process not only improves the wind power consumption capacity of the cogeneration system but also reduces the operating cost of the system by significantly reducing the coal consumption of the unit and improving the economy of the system operation.The cultural gene algorithm framework has both the global evolution process of the population and the local search for the characteristics of the problem,which has a better optimization effect on the solution.

Diesel generator exhaust heat recovery fully-coupled with intake air heating for off-grid mining operations:An experimental,numerical,and analytical evaluation

The customarily discarded exhaust from the fossil fuel-based power plants of the off-grid mines holds the thermal potential to fulfill the heating requirement of the underground operation.This present research fills in an important research gap by investigating the coupling effect between a diesel exhaust heat recovery and an intake air heating system employed in a remote mine.An integrative approach comprising analytical,numerical,and experimental assessment has been adapted.The novel analytical model developed here establishes the reliability of the proposed mine heating system by providing comparative analysis between a coupled and a decoupled system.The effect of working fluid variation has been examined by the numerical analysis and the possible improvement has been identified.Experimental investigations present a demonstration of the successful lab-scale implementation of the concept and validate the numerical and analytical models developed.Successful deployment of the fully coupled mine heating system proposed here will assist the mining industry on its journey towards energy-efficient,and sustainable mining practices through nearly 70%reduction in fossil fuel consumption for heating intentions.

Operation Strategy Analysis and Configuration Optimization of Solar CCHP System

This paper proposed a new type of combined cooling heating and power(CCHP)system,including the parabolic trough solar thermal(PTST)power generation and gas turbine power generation.The thermal energy storage subsystem in the PTST unit provides both thermal energy and electrical energy.Based on the life cycle method,the configuration optimization under eight operation strategies is studied with the economy,energy,and environment indicators.The eight operation strategies include FEL,FEL-EC,FEL-TES,FEL-TES&EC,FTL,FTL-EC,FTL-TES,and FTL-TES&EC.The feasibility of each strategy is verified by taking a residential building cluster as an example.The indicators under the optimal configuration of each strategy are compared with that of the separate production(SP)system.The results showed that the PTST-CCHP system improves the environment and energy performance by changing the ratio of thermal energy and electric energy.The environment and energy indicators of FEL-TES&EC are superior to those of FTL-TES&EC in summer,and the results are just the opposite in winter.The initial annual investment of the PTST-CCHP system is higher than that of the SP system,but its economic performance is better than that of the SP system with the increase of life-cycle.

CO_(2)Plume Geothermal(CPG)Systems for Combined Heat and Power Production:an Evaluation of Various Plant Configurations

CO_(2) Plume Geothermal(CPG)systems are a promising concept for utilising petrothermal resources in the context of a future carbon capture utilisation and sequestration economy.Petrothermal geothermal energy has a tremendous worldwide potential for decarbonising both the power and heating sectors.This paper investigates three potential CPG configurations for combined heating and power generation(CHP).The present work examines scenarios with reservoir depths of 4 km and 5 km,as well as required district heating system(DHS)supply temperatures of 70℃ and 90℃.The results reveal that a two-staged serial CHP concept eventuates in the highest achievable net power output.For a thermosiphon system,the relative net power reduction by the CHP option compared with a sole power generation system is significantly lower than for a pumped system.The net power reduction for pumped systems lies between 62.6%and 22.9%.For a thermosiphon system with a depth of 5 km and a required DHS supply temperature of 70℃,the achievable net power by the most beneficial CHP option is even 9.2%higher than for sole power generation systems.The second law efficiency for the sole power generation concepts are in a range between 33.0%and 43.0%.The second law efficiency can increase up to 63.0%in the case of a CHP application.Thus,the combined heat and power generation can significantly increase the overall second law efficiency of a CPG system.The evaluation of the achievable revenues demonstrates that a CHP application might improve the economic performance of both thermosiphon and pumped CPG systems.However,the minimum heat revenue required for compensating the power reduction increases with higher electricity revenues.In summary,the results of this work provide valuable insights for the potential development of CPG systems for CHP applications and their economic feasibility.

Schedule for Reducing the Use of Peat and the Possibilities of Replacing It with Forest Chips in Energy Production in Finland

Between 2018 and 2020, an average of 15 TWh of energy peat was consumed in Finland. Energy peat is used in 260 boilers in Finland, which produce district heat and heat and steam for industry, as well as electricity as cogeneration (CHP) in connection with district heating and industrial heat production. Peat accounts for 3% - 5% of the energy sources used in Finland, but its importance has been greater in terms of security of supply. With current use in accordance with the 2018-2020 average, the emissions from peat are almost 6 Mt CO2 per year in Finland, which is 15% of emissions from the energy sector. In this study, the technical limitations related to peat burning, economic limitations related to the availability of biomass, and socio-economic limitations related to the regional economy are reviewed. By 2040, the technical minimum use of peat will fall to 2 TWh. The techno-economical potential may be even lower, but due to socio-economic objectives, peat production will not be completely ceased. The reduction in the minimum share assumes that old peat boilers are replaced with new biomass boilers or are alternatively replaced by other forms of heat production. Based on the biomass reserves, the current use of peat can be completely replaced by forest chips, but regional challenges may occur along the coast and in southern Finland. It is unlikely that the current demand for all peat will be fully replaced by biomass when part of CHP production is replaced by heat production alone and combustion with waste heat sources.

基于预测负荷的暖通空调系统优化调度

随着我国“双碳”目标的提出,公共建筑能耗低碳化成为重点研究领域,其中基于冷热负荷预测结果优化供能系统调度策略是实现“按需供能”的有效技术手段。针对公共建筑,基于热阻法构建了冷热负荷预测模型,根据负荷预测结果,采用改进粒子群优化(PSO)算法对复合冷热源供能系统的负载、水网供回水温度和流量、阀门开度以及泵组启用台数进行迭代寻优,以供能系统运行成本、机组寿命和环保性为优化目标提出全工况最佳运行策略。基于研究成果对某公共建筑冬季供热系统进行节能改造,可在满足建筑热负荷、平衡水力工况和延长机组运行寿命的同时,分别实现降低泵组功耗10.66%、系统运行成本21.52%。结果符合理论实际,证明了所提方法的可行性与有效性,为公共建筑的按需供热、节能运行提供了有效参考。

微型冷热电联供系统的优化运行

研究了以燃气内燃机和吸附制冷机为核心的微型冷热电联供系统.以满足冷、热、电负荷需求时能源运行成本最低为优化目标,建立了联供系统经济最优化模型.并以应用场合负荷需求作为计算基础,得出具体的联供系统最优化运行策略.研究结果表明:联供系统具有良好的热经济性;联供系统最优化运行模式与能源价格有关,在天然气价格不变时,电价越高,联供系统运行经济性越好.

与电力系统协同区域型分布式冷热电联供能源系统集成方案

在分析了分布式冷热电联供系统(DES/CCHP)的研究和发展面临的新机遇的基础上,提出了与电力系统协同的区域型DES/CCHP的总体集成思路和技术集成方案。通过变结构的集成方式来实现系统结构与功能的协同优化,提出了多个区域型DES/CCHP、区域内其他形式的分布式能源系统、多源链式微网、多源环状热网和大电网的整合集成技术,并通过能源利用流程的动态组合,提出了协同互补运行方式。为清洁能源的高效、梯阶、互补利用及分布式可再生能源的规模化应用提供一种通用的集成方案。该集成方案将在湖南省创建国家示范性工程中得到应用。

分布式冷热电三联供系统节能协调优化调度

分布式冷热电三联供将是能源利用的重要发展方向。为了揭示冷热电三联供生产成本和环境成本的潜在特性,引入供热当量性能系数,将冷、热、电能量等价转化,提出了新的冷热电联供生产成本和环境成本目标函数。针对冷热、电负荷需求的不匹配性和随机性,考虑机组运行在不同的冷热电生产状态下,结合分时电价,设立了冷热电协调成本函数。由此建立了含生产成本、环境成本和冷热电协调成本的多目标节能调度模型。运用目标隶属度函数模糊算法,将其转化为单目标优化并利用二次规划法求解。算例仿真结果表明,所提出的分布式冷热电联供节能调度的模型和方法,对能源高效利用、电力经济调度和污染排放减少是有效的。

分布式冷热电联供能源系统经济性分析

冷热电联供/分布式能源系统(DES/CCHP)由于实现了能源的梯级、循环、高效利用和避免多次转换、传输损失的"就地直供",因而具有比传统方式高的能源利用效率和经济效益。我国不同地域气候、用能需求、经济条件,乃至地方政策等差异,对DES/CCHP系统经济性有很大影响。为此,重点对建筑物用途和所在地域不同导致的负荷及时间分布的差异、气电价格比,以及DES/CCHP项目所能得到的政策和经济支撑条件等3类因素对DES/CCHP系统经济性的影响进行了全面的分析:分析了冷热电负荷需求及时间分布、气电价格比影响DES/CCHP经济性的客观规律,提出了发挥集成优化和规模化的优势以改善项目经济性的对策;强调了政府规划、政策支撑、税收优惠等措施对增强DES/CCHP项目经济性的作用。

分布式冷热电多联供系统的经济运行

分布式冷热电多联供系统中冷、热、电负荷的变化和平衡具有不同的特性和规律.基于冷、热、电负荷不同平衡要求,在总供能周期内,满足机组运行约束下,以系统各供能单元的联合供能成本最小为目标函数,求解最优供能方案;将分布式供能系统分为联合供能系统、区域供能系统和"配网供电,空调供热"的传统分供系统三类,以南方某大型居民区为应用实例,对比标准煤耗量和供能企业经济性2个指标,比较分析3种供能系统的调度结果;表明:该文提出的联合供能方式能显著提高一次能源利用率,具有良好的社会综合效益.

燃料电池冷热电联供系统的技术评价指标研究

首先介绍了建筑物多联供系统传统技术评价指标,针对燃料电池联供系统的部分负荷优势,指出了传统的技术评价指标不能体现系统的年运行工况、运行时间的不足,提出了动态评价指标这一概念,将传统的静态技术评价指标改进为动态第一定律效率和动态第二定律效率两类指标,并在此基础上提出了年一次能耗因子和年二次能耗因子两个新指标,进而对FC-CCHP系统的地区适用性进行了分析,结果表明:运用新的技术评价指标可以更合理、准确地评价系统的性能,且所提出的技术评价指标亦具有一定的外延性,可以运用到以其他发电设备为原动机的建筑冷热电联供系统中,为建筑联供系统的合理科学评价提供了理论指导。

空间耦合粒子群优化算法及峰谷电价下IES-CCHP区域联合调度

综合能源系统中电力、天然气和热力系统之间的交互影响具有一定的相关性。考虑能源间转换关系以及系统对分时电价的响应,以最小化购售电计划交易成本、燃料成本和排放污染气体所产生的环境成本为目标,建立峰谷电价下冷热电联供(CCHP)系统区域联合环保经济调度模型。为解决粒子群优化算法求解模型时存在的优化效率低、易陷入局部最优、计算结果随机性强等问题,提出一种空间耦合粒子群优化算法。在粒子寻优多维参数空间上,通过引入耦合协调数学模型将各维参数有效耦合,从而使所有参数从总体上同时趋向最优解。仿真结果表明,相比经典粒子群优化算法和改进粒子群优化算法,空间耦合粒子群优化算法有较强的全局搜索能力和更可靠的优化计算结果;所提CCHP系统的联合调度模型能有效促进能源的高效利用、电力的经济调度和节能减排。

区域供冷系统经济性分析

根据冷源的不同居住区实行区域供冷可分为冷电分产和热电冷联产。以某住宅小区为例,对居住区实行区域供冷不同系统的经济性从初投资和运行费用两个方面进行了分析,为正确的进行区域供冷的冷源选择提供参考。

冷热电联产系统的两级调峰方案研究

当前冷热电联产系统多采用蓄能装置(如蓄能水箱)调节用户冷热日负荷的变化,但对于季节性负荷的峰谷差却没有很好的调节方法.针对这一问题,建立以燃气轮机为原动机的冷热电联产系统,利用回热器和蓄能水箱构建两级调峰系统,实现对日负荷和季节性负荷的同步调节.计算分析表明,在满足用户全年各时段冷热负荷的前提下,燃气轮机实现了全年满负荷发电,并且系统的节能效果也有所提高.

基于热电厂的热电冷三联产技术及评价标准

论述以原有热电厂为基础建立的热电冷联供系统的可行性、经济性和节能效率。该系统对城市局部的自有热网建设有所裨益 ,并能满足社会需求。经济分析证明 ,采用高参数的锅炉和汽轮机更具优势。

中国低碳能源格局中的天然气

2009年底的哥本哈根会议开启了世界走向低碳能源的新时代。为此，分析了低碳时代世界及中国一次能源构成的变化情况，结论指出：在控制温升不超过2℃的情况下，要求把能源消耗产生的COz控制在100×10^8t／a，这将导致目前石油、煤、天然气、核能与可再生能源在总能耗构成中的比率逆转和终端用能模式巨变，2020--2050年中国天然气将在工业燃料、商住和民用能源、调峰发电、交通几大领域占据主导或重要地位，并将在冷热电联供分布式能源系统、CNG汽车和LNG汽车技术领域自主创新，领先于世界；中国非常规天然气资源丰富、开发前景看好，自给率可达70％；2020--2030年中国天然气消费规模将达到（4000-6000）×10^8m^3／a，将对世界天然气市场发生积极、正面的影响。

燃气冷热电分布式能源机组调试及主要问题分析处理

介绍了武汉某燃气冷热电分布式能源站一期工程2台4.04 MW燃气内燃发电机组和2台3.60 MW烟气热水型溴化锂机组的系统构成和运行特点,分析了燃气冷热电分布式能源机组调试过程中内燃机轴承温度偏高、溴化锂机冷却水流量不足和冷热水流量偏差问题,以及内燃机缸套水管道排气不畅等问题,并提出了调试解决方案,可以为同类分布式能源机组调试提供参考。