Polish District Heating Systems--Development Perspectives

The most economical and rational means of heat supply for city inhabitants are district heating systems. Heat generated in power plants and large heat sources is cheaper than heat from individual sources. The reason for that is the amount of the generated heat and the used fuel （coal for most heat sources）. District heating, a very important energy sub-sector for the Polish economy, provides heat supply to centralised heating systems, which, on average, satisfy 72% of the demand for heat in Polish cities. Therefore, several million Polish citizens use heat from district heating systems that produce heat in professional, industrial and municipal power plants. In Europe, over 100 million citizens use district heating systems. The present situation of the Polish district heating sector is a result of Poland＇s transformation that took place at the beginning of the 1990s. The reform put the obligation of heat supply on the local authorities, on the municipality, instead of the state. Along with the transformation, district heating also made huge technological and technical progress. Increasing expectations of recipients posed new challenges for the branch, however.

A Neuro-Fuzzy Based Adaptive Set-Point Heat Exchanger Control Scheme in District Heating System

The control of heat exchange stations in district heating system is critical for the overall energy efficiency and can be very difficult due to high level of complexity. A conventional method is to control the equipment such that the temperature of hot water supply is maintained at a set-point that may be a fixed value or be compensated against the external temperature. This paper presents a novel scheme that can determine the optimal set-point of hot water supply that maximizes the energy efficiency whilst providing sufficient heating capacity to the load. This scheme is based on Adaptive Neuro-Fuzzy Inferential System. The aim of this study is to improve the overall performance of district heating systems.

Operation Performance of Central Solar Heating System with Seasonal Storage Water Tank in Harbin

This paper presented a preliminary research on the central solar heating system with seasonal storage(CSHSSS)used in cold climate in China.A mathematical model of the solar energy seasonal storage water tank used in the central solar heating system was firstly developed based on energy conservation.This was followed by the simulation of the CSHSSS used in a two-floor villa in Harbin,and analysis of the impacts on storage water temperature of tank volume,solar collector area,tank burial depth,insulation thickness around the tank,etc.The results show there is a relatively economical tank volume to optimize the system efficiency,which decreases with increasing tank volume at the constant collector area,and increases with increasing collector area at the constant tank volume.Furthermore,the insulation thickness has obvious effect on avoiding heat loss,while the tank burial depth doesn't.In addition,the relationship between the solar collector efficiency and storage water temperature is also obtained,it decreases quickly with increasing storing water temperature,and then increases slowly after starting space heating system.These may be helpful for relevant design and optimization in cold climates in China and all over the world.

Initiative Optimization Operation Strategy and Multi-objective Energy Management Method for Combined Cooling Heating and Power

This paper proposed an initiative optimization operation strategy and multi-objective energy management method for combined cooling heating and power U+0028 CCHP U+0029 with storage systems. Initially, the initiative optimization operation strategy of CCHP system in the cooling season, the heating season and the transition season was formulated. The energy management of CCHP system was optimized by the multi-objective optimization model with maximum daily energy efficiency, minimum daily carbon emissions and minimum daily operation cost based on the proposed initiative optimization operation strategy. Furthermore, the pareto optimal solution set was solved by using the niche particle swarm multi-objective optimization algorithm. Ultimately, the most satisfactory energy management scheme was obtained by using the technique for order preference by similarity to ideal solution U+0028 TOPSIS U+0029 method. A case study of CCHP system used in a hospital in the north of China validated the effectiveness of this method. The results showed that the satisfactory energy management scheme of CCHP system was obtained based on this initiative optimization operation strategy and multi-objective energy management method. The CCHP system has achieved better energy efficiency, environmental protection and economic benefits. © 2014 Chinese Association of Automation.

Applicability of sewage heat pump air-conditioning system

A sewage heat pump system and its application based on a project in Chongqing,China,were discussed. Based on the sewage conditions,a feasibility analysis of the sewage heat pump air conditioning system was conducted. The theoretical and quantitative calculations indicate that sewage flux in the city sewage main pipe in the project can satisfy heat exchange requirements,and taking water from the pipes has relatively small influence on the pipe net in summer and winter. The sewage heat pump air-conditioning system can save 21.5% operating cost in one year,which is energy efficient and environmentally friendly.

District heating system operation in power systems with high share of wind power

The integration of continuously varying and not easily predictable wind power generation is affecting the stability of the power system and leads to increasing demand for balancing services.In this study,a short-term operation model of a district heating system is proposed to optimally schedule the production of both heat and power in a system with high wind power penetration.The application of the model in a case study system shows the increased flexibility offered by the coordination of power generation,consumption and heat storage units which are available in district heating systems.

Energy efficiency and carbon dioxide emissions reduction opportunities in district heating source in Tianjin

Building a trading market can promote energy conservation provided that the trading method is deter- mined. Energy consumption for heat supply is huge. Tianjin Municipal Government is planning to establish an energy efficiency trading platform for district heating taking into consideration the experience in carbon trading market and specific situation in Tianjin. This paper presented an in-depth analysis of the district heating industry in Tianjin municipality, and identified the potentials of energy saving and carbon dioxide emissions reduction. Since energy efficiency was closely related to different heating source technologies, baselines were determined for boiler plants and thermal power plants respectively. Three scenarios were discussed for baseline determination. 472 boiler plants were surveyed and operational data relating to energy consumption were collected. Through data analysis, 27 boiler plants which have reasonable recorded energy consumption values were chosen as samples. By analyzing the dataset and referring to the related standards, method of determining the baseline for district heating carbon market was established. Finxally, the baseline for boiler plant was determined to be 52.0 kgce/GJ, and that for thermal power plant was 43.0 kgce/GJ in 2011. Carbon abatement against the baselines above was calculated and considerable carbon dioxide emissions reduction could be achieved.

Performance Assessment of a Heat Recovery Unit Utilizing Turbine with Variable Inlet Guide Vanes Configuration for Application in Passenger Vehicles

This study explores the potentials of employing an Organic Rankine Cycle (ORC) system with variable inlet guide vanes (VIV) turbine geometry designed on a GT-Suite platform for effective exhaust heat recovery (EHR) application onboard passenger vehicles. The ORC model simulation was based on vehicle speed mode using R245fa as working fluid to assess the thermal performance of the ORC system when utilizing modified turbine geometry. Interestingly, the model achieved a very improved performance in contrast to the model without a modified turbine configuration. The results revealed the average 2.32 kW ORC net output, 4.93% thermal efficiency, 6.1% mechanical efficiency, and 5.0% improved brake specific fuel consumption (BSFC) for the developed model. As determined by the performance indicators, these promising results from the model study show the prospect of EHR technology application in the transportation sector for reduction in exhaust emissions and fuel savings.

Enhancing Wind Power Integration through Optimal Use of Flexibility in Multi-Carrier Energy Systems from the Danish Perspective

Denmark’ goal of being independent of fossil energy sources in 2050 puts forward great demands on all energy subsystems (electricity, heat, gas and transport, etc.) to be operated in a holistic manner. The Danish experience and challenges of wind power integration and the development of district heating systems are summarized in this paper. How to optimally use the cross-sectoral flexibility by intelligent control (model predictive control-based) of the key coupling components in an integrated heat and power system including electrical heat pumps in the demand side, and thermal storage applications in buildings is investigated.

Neural Network Based Feasible Region Approximation Model for Optimal Operation of Integrated Electricity and Heating System

This paper proposes a neural network based feasible region approximation model of a district heating system(DHS),and it is intended to be used for optimal operation of integrated electricity and heating system(IEHS)considering privacy protection.In this model,a neural network is trained to approximate the feasible region of the DHS operation and then is reformulated as a set of mixed-integer linear constraints.Based on the received approximation models of DHSs and detailed electricity system model,the electricity operator conducts centralized optimization,and then sends specific heating generation plans back to corresponding heating operators.Furthermore,subsequent optimization is formulated for each DHS to obtain detailed operation strategy based on received heating generation plan.In this scheme,optimization of the IEHS could be achieved and privacy protection requirement is satisfied since the feasible region approximation model does not contain detailed system parameters.Case studies conducted on a small-scale system demonstrate accuracy of the proposed strategy and a large-scale system verify its application possibility.

计及氢能高效利用和热电灵活输出的综合能源系统源荷灵活运行策略

为进一步发挥氢能高效利用优势,构建绿色低碳能源系统,提出一种计及氢能高效利用和热电联产灵活输出的综合能源系统源荷灵活运行策略。首先,对源侧供能模型进行两方面改进:一是引入含风电制氢、燃气混氢、多能用氢和储氢的氢能利用模型,并考虑到电解水和甲烷化反应过程中的热量散失情况,引入热量回收装置,构建计及热量回收的氢能高效利用模型;二是针对常规热电联产灵活性不足的问题,构建含电锅炉和有机朗肯循环的热电灵活输出模型,以解耦常规热电联产“以热定电”和“以电定热”限制。其次,在荷侧引入含可转移、可削减和可平移的电、热柔性负荷,以缓解电、热负荷峰谷差,并与源侧相结合,形成源荷灵活运行模型。最后,综合考虑阶梯型碳交易成本、设备运行维护成本、弃风成本以及购能成本,建立综合能源系统源荷灵活优化运行模型。采用CPLEX求解器对所提综合能源系统源荷灵活运行模型进行求解,并设置不同场景进行对比。结果表明,相比常规氢能利用模型,考虑所提计及热量回收的氢能高效利用模型时,系统的总成本、碳排放量分别降低了1.92%、4.22%,并且引入热电联产改进模型后,其总成本、碳排放量可进一步降低4.08%、7.32%,实现系统低碳、经济和灵活运行。

吸收式热泵-太阳能联合供热系统性能影响因素研究

为提高供热系统的供热能力,以吸收式热泵-太阳能联合供热系统为研究对象,通过分析联合供热系统原理并建立供热系统热力模型,对供热系统性能影响因素进行了分析。仿真结果表明,吸收式热泵-太阳能联合供热系统性能受多种干扰因素影响,包括聚光型集热器面积和流量、吸收式热泵容量和蓄热水箱容积。其中,增加聚光型集热面积和吸收式热泵容量,减小聚光型集热器流量和蓄热水箱容积,可有效降低平板集热器进口温度,提高平板集热器集热效率,使供热系统供热温度和供热量增加,进而提高供热系统供热能力。

基于TRNSYS的扁平热管PV/T系统性能优化

基于太阳能技术现状分析,将太阳能光伏组件与扁平式热管高效结合,提出新型扁平热管PV/T系统.为实现该系统综合效率最大化,结合TRNSYS仿真,开展试验并进行优化分析.结果表明,安装扁平热管后夏季热水温度从原来的51.1℃升高到57.3℃,提高了12.1%,冬季热水温度从47.6℃升高到55.2℃,提高了15.9%.夏季系统的综合效率提高了4.7%、冬季系统的综合效率提高了4.8%.可以得出结论扁平热管对PV/T空调系统性能的优化效果明显,也为该技术在建筑领域的应用提供了依据.

BENEFITS AND COSTS IN SELECTING FUEL FOR MUNICIPALITY HEATING SYSTEMS WITH THE ANALYTIC HIERARCHY PROCESS

Municipal economy problems are of a complex nature. Existing requirements for sustainable development make us apply various criteria while solving these problems. These can, for example, include economic, financial, social and environmental criteria. To handle them effectively, multi-criteria analysis should be applied. Decisions about heat production and delivery systems belong to such multidisciplinary problems. They were usually resolved in the past using classical numerical methodology that took into account only the technical and economic merits of the various alternatives. By applying multi-criteria tools instead it is possible to obtain more realistic results and make more effective decisions. The Analytical Hierarchy Process （AHP） seems to be a good alternative to fill the existing gap between decision-making as it is actually practiced and the traditional methods when applied to selecting district heating （DH） systems. This paper presents such an application. Our application is to select the best heat energy source for a DH system for a medium sized city located in Poland. Our results led to an interesting conclusion with regard to the best heat energy source. Our results suggest that intensifying the effort to make widespread the use of more efficient, but financially more costly, energy sources is the best.

西藏高原零碳太阳能区域供暖新模式与实践

西藏高原冬季寒冷漫长,煤炭、天然气等常规能源储量近乎为零,建筑供暖挑战极大。然而,当地太阳能资源极其丰富,具备利用太阳能实现建筑零碳供暖的先决条件。针对西藏高原“绿洲型”县城和乡镇,对“规模化太阳能集热+大型水体蓄热+建筑围护结构差异化保温+南北分环独立供暖”全链条零碳太阳能区域供暖模式进行了探索,阐述了规模化太阳能集热技术与产品、大型蓄热水体容量配置与高效蓄取热技术、建筑围护结构“差异化保温”设计方法、南北分环双独立供暖新系统等成套关键支撑技术与方法,并介绍了供暖新模式在西藏高原的工程实践经验与成效。

以氨为工质的雪车雪橇赛道制冰系统能效提升的讨论

本文对北京延庆地区冬奥会用雪车雪橇赛道制冰系统能效提升方式进行了研究,提出采用补气压缩、自然冷源利用和高效传热末端等几种性能提升改进措施,并对提升效果进行了计算。结果表明:采用一次中间补气制冷性能系数(COP)最大可提升3.33%,二次中间补气制冷COP最大可提升3.96%;利用自然冷源可以获得2.24%的提升效果;采用制冰末端管路铺设铝板和应用平板微热管两种高效传热末端方案,系统制冷COP分别可提升5.8%和6.14%;对冷凝热进行回收利用会使制冷COP降低,但系统综合COP可以达到7.04。

重型柴油机排气电加热NO_(x)排放控制技术研究

为解决重型柴油机在冷起动工况下的NO_(x)排放恶化问题,基于重型柴油机冷起动试验平台,自主设计了排气电加热系统,并研究了不同电加热功率对后处理后的NO_(x)排放和每度电可处理的NO_(x)排放的影响.结果表明:随着电加热功率从2 kW升高至8 kW,NO_(x)排放逐渐降低,每度电可处理的NO_(x)排放逐渐升高;电加热功率固定为8 kW时,NO_(x)排放达到最低(140.3 mg/(kW·h)),相比原机减少了51.55%;电加热功率固定为2 kW时,每度电可处理的NO_(x)排放最多为1 900.8 mg.基于此,通过仿真进行排气电加热器控制策略的开发,控制策略引入NO_(x)转化效率和燃油消耗量作为判据,每度电可处理的NO_(x)排放增加了19.27%.此时,仅消耗0.21 kW·h电能,即可将后处理后的NO_(x)排放从274.76 mg/(kW·h)降低至231.42 mg/(kW·h).

电-热-氢综合能源系统鲁棒区间优化调度

储能技术与风电相结合实现电能的时空平移是解决系统运行稳定性问题的有效手段。氢储能具有储存容量大、可实现电热联产联供的优点,具有很大的发展潜能。然而由于风电存在不确定性,氢储能系统在频繁切换工作模式时面临着不确定的热能需求。因此,文中综合考虑氢储能在间歇模式下的热能需求,首先,介绍了氢储能系统接入的电-热综合能源系统基本结构,将风电场与氢储能相结合构成风-氢混合系统;然后,提出考虑风-氢混合系统热平衡需求不确定性的电-热综合能源系统鲁棒区间优化调度模型;最后,基于对偶理论,对所提出的模型转化求解,通过算例对比分析各类情况优化结果,验证了氢储能在促进风电消纳、提高系统能源综合利用率方面的有效性,并证明了考虑电解槽和燃料电池工作温度能提高系统的工作效率并提高风电场并网功率。

余热回收型空气源热泵烘干系统设计与能效实验

采用电能空气源热泵替代传统的木柴燃烧进行经济农作物烘干具有节能环保、降本增效等优点。针对空气源热泵烘干过程中热量随高温空气流失而降低了能源利用率的问题,设计了一款余热回收再利用的空气源热泵烘干系统,首先通过调节新风阀与回风阀开度使热风在烘干机内持续循环;然后通过热回收器与热泵将排出的高温空气余热回收,可显著提升热能的利用效率。为量化空气源热泵的电热转换与烘干加热过程能源利用率,研究了两级能效指标。一级能效指标可衡量电热转换与回收的利用效率;二级指标可直接衡量电能对产量的产出效率。研制了余热回收型空气源热泵烘干样机系统,并设计了一套远程监控系统,可在云端和手持终端实时在线监控作业过程和状态,控制烘干作业的工艺流程,并计算两级能效指标。食用菌烘干实验结果表明:该余热回收型空气源热泵烘干系统样机的一级能效指标为84.69%、二级指标为4.37 kg/(kW·h),具有能效利用率高、安全可靠等优点。