小型热电联产项目方案优化简析

文章从设计基本原则、用户负荷实际需求、系统的优化设计、项目可行性评估、动态运行评估及调度优化等方面进行分析，提出了小型热电联产系统方案优化的设想。     

热电冷联产系统节能性的(火用)分析

利用分析的方法,定义了等效发电效率,对常用热电冷联产系统形式的节能性进行了分析。认为相对于全国平均供电煤耗而言,热电冷联产系统的节能是有条件的,应选取合理的方式,优化设计和运行方案;相对于当前有些热电厂夏季负荷不足的情况,热电冷联产是节能的,在不同的情况下节能率在7.8%~39%之间。建议利用现有的热电联产条件,发展热电冷联产系统,提高现有热电厂的设备利用率和运行经济性。     

热电冷联产系统节能性的[火用]分析

利用[火用]分析的方法，定义了等效发电[火用]效率，对常用热电冷联产系统形式的节能性进行了分析。认为相对于全国平均供电煤耗而言，热电冷联产系统的节能是有条件的，应选取合理的方式，优化设计和运行方案；相对于当前有些热电厂夏季负荷不足的情况，热电冷联产是节能的，在不同的情况下节能率在7．8％～39％之间。建议利用现有的热电联产条件，发展热电冷联产系统，提高现有热电厂的设备利用率和运行经济性。     

热电联产电力调峰时供热系统的调节

热电联产电力调峰是解决供电峰谷差的重要途径,利用集中供热系统的热惯性是实施热电联产电力调峰的有效途径。在热电联产电力调峰运行模式下,热源供热量随电力负荷的变化而变化,供热系统内各点的供热介质温度及供暖室内温度也随之变化。为不影响供热质量,须控制供暖室内温度的波动幅度,此时热电联产电力调峰的幅度受热源的调节能力、集中供热系统的热惯性的影响。探讨了利用集中供热系统热惯性实施热电联产电力调峰运行模式时集中供热系统的4种运行调节方式。     

企业自备热电厂的节能性分析

以余姚市某化纤企业自备热电厂热电联产系统为研究对象,对其热、电负荷做了计算,同时用标准煤耗量和总热效率2个指标对系统进行节能性分析。分析结果表明:热电联产系统节能性要优于分产系统,实施热电联产后全厂总热效率提高27.3%,在企业年生产总量不变的条件下,年节约标准煤18125.55t,极大地节约运行成本。文章最后还指出该系统在夏季运行时热负荷减少导致发电量减少,并提出将系统改进为热电冷联产系统的建议。实行热电冷联产后,系统总热效率较原来夏季热电联产系统总热效率提高24.7%,系统节能性进一步提高。     

积极准备小型燃气热电联产系统应用

小型燃气热电联产具有发电效率高、能源能充分利用、良好的环保、投资成本低、建设时间短及运行简单等优点,可作为今后发展热电联产的首选。根据用户对热力产品的需求不同,联产系统可以有不同的组合形式。但在推广燃气热电联产时必须要有必要的技术准备以及相应的政策。     

热电厂供暖系统技术经济分析的有关问题

热电厂供暖系统是以热电厂汽轮机同时生产电能和热能的热电合供系统。其抽汽压力的高低及不同抽汽压力对应的各个不同热水供暖系统可供年度供热量的大小及系统的调节都直接关系到热电厂的运行效率、热电产量、供暖效果及投资情况。     

智慧蒸汽供热系统助力南方供热企业提质扩量增效

建设智慧蒸汽供热系统是解决我国南方蒸汽热网高效低碳运行、合理扩建改造难题的有效手段。介绍了智慧蒸汽供热系统的技术方案,建立的智慧蒸汽供热系统主要包含热网建模仿真、运行调度优化决策、负荷预测、安全预警、网损检测及管控等技术模块。基于智慧蒸汽供热系统在合肥热电集团的典型应用案例,阐释了智慧蒸汽供热系统通过热网饱和点位分析、用户综合分析评估、热网网损分析、管网优化运行分析和历史数据分析功能指导园区蒸汽供热系统运行的方式和应用效果。     

某医院建筑应用冷热电三联供系统的可行性分析

本文以上海某医院建筑作为冷热电三联供系统计算与分析为基础,对医院建筑的能耗特性进行了深入探讨,引入热电比、热电比频数和热电比时间数的概念,用以反映该医院建筑的冷、热、电负荷特性,得出医院建筑是冷热电三联供系统较合适用户的结论。     

冷热电联供系统中“以热定电”与“以电定热”的分析研究

为平衡冷热电联供系统中负荷变化,解决冷热电供需不平衡的问题,对燃气轮机冷热电联供的运行方式进行了优化选择。根据系统规模及容量,选择燃气轮机作为联供系统的原动机,同时选用了冷热电联供系统常用的两种运行模式:"以热定电"和"以电定热"。本文从热电输出和燃料消耗量两个方面比较分析了联供系统在两种运行模式中的性能差异,通过冷热电联产公式计算及Aspen Plus软件建模分析表明:当实际的热电输出等于终端的热电需求时,其最佳热电比HPR为1.75;当热电需求比在1≤HPR<1.75区间时,"以热定电"为最佳的系统运行方式;当热电需求比在1.75相似文献   

Performance assessment of fuel cell micro-cogeneration systems for residential buildings

The reduction of greenhouse gas emissions in the building sector to a sustainable level will require tremendous efforts to increase both energy efficiency and the share of renewable energies. Apart from the lowering of energy demand through better insulation and fenestration, small combined heat and power (micro-cogeneration) systems may help improve the situation on the supply side by cutting both the non-renewable energy demand for residential buildings and peak loads in the electric grid. Though still on the brink of market entry, fuel cells are the focus of interest as the prime technology for such systems. In this study, a methodology for assessing the performance of such systems in terms of primary energy demand and the CO₂ emissions by transient computer simulations is established, and demonstrated for a natural gas driven solid oxide fuel cell (SOFC) and, to a lesser extend, a polymer electrolyte fuel cell (PEFC) home fuel cell cogeneration system. The systems were evaluated for different grid electricity generation mix types and compared to traditional gas boiler systems. The interaction with hot water storage and solar thermal collectors, and the impact of storage size and predictive control was analyzed. Typical heat and electricity demand load profiles for different types of residential buildings and occupancy were considered, and the sizing of the fuel cell system in relation to the heat demand of the building was analyzed. Primary energy savings decline for cases with lower heat demand and for cases with solar thermal systems, and peak for fuel cell systems sized in accordance with the heat demand of the building. Future assessments of fuel cell systems will need a refined methodology, and depend on realistic performance characteristics and models that accurately consider dynamic conditions.     

Load prediction method for heat and electricity demand in buildings for the purpose of planning for mixed energy distribution systems

Energy planning for mixed energy distribution systems is important to increase the flexibility in the regional and national energy systems. Expected maximum loads, load profiles and yearly energy demands, all divided into heat and electricity purposes, are important input parameters to plan for the most economical, technical and environmental optimal energy distribution system for a planning area. First, this article presents a load prediction method which estimates heat and electricity load profiles for various building categories. The method is based on statistical analyses of hourly simultaneous measured district heat and electricity consumption in several buildings, as well as background information of the measured buildings. The heat load model is based on regression analyses, whereas the electricity load model is based on various statistical distributions. Second, a method for load aggregation based on the building categories’ load profiles is presented to estimate the maximum load demands, yearly load profiles, load duration profiles and yearly energy demands, all divided into heat and electricity purposes, for a planning area.     

Reversible heat pump model for seasonal performance optimization

Building is one of the economical sectors where solutions are available to significantly reduce energy consumption and greenhouse gases emissions. Electric heat pumps are one of the solutions favored in Europe. Europe recently adopted a conventional primary energy to electricity ratio which enables to compare electric heat pumps and fossil fuel boilers. This leads to an increased consideration for the evaluation of the seasonal performances of heat pumps.Nowadays, the design and sizing of heat pumps are still based on full load performance in order to fulfill thermal comfort under extreme conditions. However, the HVAC industry is switching to designs based on improved seasonal performance. The objective of this work is to model an air to water reversible heat pump that can re-design its components for seasonal performance improvement.In this context, we will present a system model including detailed sub-models of each component of the system: heat exchangers, compressor, and expansion valve. The model converges with the system thermodynamic equilibrium after simulating each component separately. Results obtained are validated through experimental data per component and for the whole cycle. Modeling requirements for the purpose of simulating seasonal performance improvements are discussed.     

Economic and environmental evaluation of micro CHP systems with different operating modes for residential buildings in Japan

The growing worldwide demand for less polluting forms of energy has led to a renewed interest in the use of micro combined heat and power (CHP) technologies in the residential sector. The operation of micro CHP system results in simultaneous production of heat and power in a single household based on small energy conversion units. The heat produced may be used for space and water heating and possibly for cooling load if combined with an absorption chiller, the electricity is used within the house.In this paper, two typical micro CHP alternatives, namely, gas engine and fuel cell for residential buildings, are analyzed. For each facility, two different operating modes including minimum-cost operation and minimum-emission operation are taken into consideration by employing a plan and evaluation model for residential micro CHP systems. The analysis results show that the fuel cell system is recognized as a better option for the examined residential building from both economic and environmental points of view. With the operation considering optimal economic benefits, annual energy cost is reduced by about 26%. On the other hand, while maximizing the environmental merits, annual CO₂ emissions are reduced by about 9%.     

吐鲁番市热电冷联产联供方案的探讨

介绍了吐鲁番市实现热、电、冷联产联供的方案论证,文中共提出四个方案,均以天然气作为燃料,前两个方案为热,电、冷联产联供,后两个方案为热,冷联产联供。     

内燃机驱动的热泵系统数值计算和性能分析

建立了内燃机驱动的空调系统各部件数学模型,利用该模型,研究了不同转速下的热泵系统特性以及整体性能,与试验结果对比,二者吻合良好,说明内燃机驱动的空调系统具有较好的部分负荷特性及较好的节能环保效果,是一种高效、清洁、利用能源的技术。     

Primary energy implications of end-use energy efficiency measures in district heated buildings

In this study we explore the effects of end-use energy efficiency measures on different district heat production systems with combined heat and power (CHP) plants for base load production and heat-only boilers for peak and medium load productions. We model four minimum cost district heat production systems based on four environmental taxation scenarios, plus a reference district heat system used in Östersund, Sweden. We analyze the primary energy use and the cost of district heat production for each system. We then analyze the primary energy implications of end-use energy efficiency measures applied to a case-study apartment building, taking into account the reduced district heat demand, reduced cogenerated electricity and increased electricity use due to ventilation heat recovery. We find that district heat production cost in optimally-designed production systems is not sensitive to environmental taxation. The primary energy savings of end-use energy efficiency measures depend on the characteristics of the district heat production system and the type of end-use energy efficiency measures. Energy efficiency measures that reduce more of peak load than base load production give higher primary energy savings, because the primary energy efficiency is higher for CHP plants than for boilers. This study shows the importance of analyzing both the demand and supply sides as well as their interaction in order to minimize the primary energy use of district heated buildings.     

燃料载荷和含水率对平坡地表火蔓延影响实验研究

燃料载荷和含水率是森林火灾中地表火蔓延的重要影响因素.选取香樟叶和云南松松针作为研究对象,开展了不同燃料载荷和含水率条件下平坡地表火蔓延实验.研究结果表明:同一燃料载荷下,随含水率增大,火焰长度、火蔓延速率、火线强度和辐射热流减小,滞留时间增大;同一含水率下,燃料载荷增大,火焰长度、火蔓延速率、火线强度、辐射热流和滞留...     

A new energy analysis tool for ground source heat pump systems

A new tool, suitable for energy analysis of vertical ground source heat pump systems, is presented. The tool is based on analytical equations describing the heat exchanged with the ground, developed in Matlab^® environment. The time step of the simulation can be freely chosen by the user (e.g. 1, 2 h etc.) and the calculation time required is very short. The heating and cooling loads of the building, at the afore mentioned time step, are needed as input, along with the thermophysical properties of the soil and of the ground heat exchanger, the operation characteristic curves of the system's heat pumps and the basic ground source heat exchanger dimensions. The results include the electricity consumption of the system and the heat absorbed from or rejected to the ground. The efficiency of the tool is verified through comparison with actual electricity consumption data collected from an existing large scale ground coupled heat pump installation over a three-year period.     

基于热气机分布式冷热电三联供效益分析

以上海地区一幢典型五层住宅建筑热、电、冷负荷需求为计算基础,分别计算了基于热气机的冷热电三联供系统和传统冷热电分供系统的一次能耗率、全年净收益以及投资回收期,验证了三联供系统的节能性和经济性。分析表明热气机余热利用率和能源价格是影响该三联供系统节能效益和经济效益的主要因素。