Verification of energy efficiency of district heating and cooling system by simulation considering design and operation parameters

This paper aims to verify the advantages of district heating and cooling (DHC) systems in terms of energy efficiency. From the measurement data, the parameters that characterize the energy efficiency of a heating/cooling plant are identified for DHC and an individual building. A simulation model that considers the difference in these parameters is developed. This model examines both the advantages and disadvantages of DHC systems and the effect of each parameter. The results show that the energy efficiency for cooling in DHC systems is superior to that in the case of individual cooling systems because of the “concentration effect” and “grade of operation”.     

浅析日本区域供冷供热的负荷预测

介绍了日本区域供冷供热领域中冷负荷、热负荷、用电负荷、生活热水加热负荷的设计值和全年累计值,以及逐时逐月的变化规律.该数据是基于对大量建筑物的实际能耗进行收集、统计分析后得出的,可供中国设计师在初期规划阶段参考、借鉴.     

冷热电三联供实例经济性分析

以某地区实际运行的数据为基础，对冷热电联产用户侧和电厂侧的经济性进行了分析。介绍了当前热电企业夏季的实际运行情况，为冷热电联产在用户端的推广提出了建议。     

区域供能地下敷设输配管网传热分析方法

地下敷设是区域供能输配管网的主要敷设方式,其传热计算用于确定保温层厚度、输配管网附加负荷、热损坏可能性。分析了影响地下敷设管网传热的因素,包括:流体与土壤之间的温差、管道的保温隔热性能、埋深、土壤导热系数以及相邻管道之间的间距。介绍了基于热阻的简化稳态计算方法,该方法极大地简化了计算工作量,且计算结果能够满足工程需要,同时该方法适用于大多数地下敷设管网的形式,可供工程设计人员参考。     

Verification of the energy-saving effect of the district heating and cooling system—Simulation of an electric-driven heat pump system

A district heating and cooling system (DHC) is expected to be a promising energy-saving measure for high-density business areas in Japan. However, it has not been verified what advantages of the DHC are important for energy conservation. The clarification of this issue is supposed to contribute to improving the energy efficiency of the DHC.     

建筑环境设计模拟分析软件DeST第9讲冷热源与水系统模拟分析(下)

冷热源系统是整个集中空调系统的核心,它决定了系统能否保障用户的冷热需求,是投资的主要部分,也是能源消耗的主要部分。同时冷热源产生的冷热量主要依靠水系统输配到各末端用户中去。因此冷热源与水系统的联合优化设计是整个空调系统设计过程中至关重要的环节。综述了目前冷热源与水系统联合模拟的现状,详细阐述了DeST模拟软件中冷源和水系统模拟所采用的的模型与模拟方法。通过介绍一个设计实例,指出了冷热源与水系统全工况模拟的应用范围和实际意义。     

Study and demonstration of pressure wave-based leak detection in a district heating network

A district heating network (DHN) is one of the most important infrastructures in cities and towns of countries with colder weather. Citizens generally use DHN services for hot water supply all year round and also for space heating during winter. It is important that in case of an accident this service would be restored as soon as possible, causing minimal damage or inconveniences for the customers. In addition, it is important to minimise losses of the DHN operator. This study demonstrated a possibility of leak location in DHN using the data from the pressure sensors in the network, employing the negative pressure wave (NPW) method. The mass balance in the DHN is measured at the heating source, which acts as a confirmation of a leak in a closed system. The experiments in the real DHN were performed and the data was used to trace the leak location. Numerical modelling tools were used to model pressure transients during pipe break accident under various conditions in order to predict the effectiveness and limitations of the leak detection system.     

热网供回水压力及供热质量的分析研究

对集中供热管网的供回水压力问题进行了分析,并运用simulink对管网动态系统进行模拟,具体分析供热管网的运行状态,提出了调节阀的调节值,保证了热网的供热质量,满足用户的用热要求。     

在热力管网工程中深井降水的应用及测算

对轻型井点降水与深井降水作了对比分析,介绍了深井涌水量计算、深井井距的确定以及打井与水泵的选择,指出深井降水的效果良好,是一个重要的工程技术经济问题.     

生态型节能屋面的研究（之二）——种植屋面实测结果与数值模拟的对比分析

通过对一例种植屋面的实际测试,对比分析了这种屋面和夏季隔热和冬季保温效果。模拟计算结果与实际测试结果的比较,证明了种植屋面系统数学模型的正确性和实用性。根据模拟计算结果,分析了种植屋面系统能量平衡各顶的变化,并讨论了屋面采用种植以后,内表面热流量的变化,引出种植屋面隔热（保温）效率。     

太原市给水管网动态仿真系统的建立和运行

结合目前太原市供水现状,通过城市管网的静、动态数据的收集,建立了给水管网动态仿真系统,并对其进行了仿真动态模拟计算,最后就模型的运用及维护作了分析,以实现科学调度城市管网的目标。     

基于BP神经网络的污水处理水质建模与模拟

分析了BP神经网络原理及污水处理过程中BP网络模型设计,经过对苏州市某污水厂123组实测数据异点剔除和归一化处理后,对网络进行了训练和学习,30组数据用来检验网络,并用另外70组实测数据进行了实际仿真模拟,分析模拟结果表明,对各出水水质指标的模拟平均相对误差均小于5%,建立BP神经网络活性污泥法污水处理过程模型是有效的、可行的。     

Heat supply to low-energy buildings in district heating areas: Analyses of CO2 emissions and electricity supply security

In several housing development projects in Norway the requirements related to the mandatory connection to district heating plants have shown to be a barrier for building low-energy residential buildings. The developers have considered the costs related to both low-energy measures and a space heating system that can utilize district heat to be too high to give the project acceptable profitability. In these projects the developers wanted to use a cheaper electric space heating system. Based on models representative for the range of the Norwegian district heating plants, calculations show that the CO₂ emissions related to heating in residential buildings with an energy standard in accordance with the new building regulations and that are connected to the district heating grid, are lower than for similar buildings with a low-energy standard and with heating based on electricity. However, in a long term perspective the differences are marginal when considering the national annual CO₂ emissions. Similarly, increased peak power demand due to electricity-based heating may also be regarded as marginal when compared to the present maximum peak power capacity in Norway.     

集中供热系统二级网分布热源设置及应用分析

介绍了基础热源与分布热源联合运行的两种模式,分别以年运行费用和寿命周期内费用年值最小为目标建立了联合运行的经济模型。以哈尔滨某集中供热系统为例,进行了应用分析。结果显示,"基础热源+分布热源"联合供热系统比单热源供热系统更节省年运行费用,若从动态经济性考虑,节省的寿命周期内费用年值更为可观。分别以年运行费用最小和寿命周期内费用年值最小为目标优化得出的最佳基础热源容量系数为0.70～0.75和0.60～0.65。     

Overview of pressure coefficient data in building energy simulation and airflow network programs

Wind pressure coefficients (C_p) are influenced by a wide range of parameters, including building geometry, facade detailing, position on the facade, the degree of exposure/sheltering, wind speed and wind direction. As it is practically impossible to take into account the full complexity of pressure coefficient variation, building energy simulation (BES) and Airflow network (AFN) programs generally incorporate it in a simplified way. This paper provides an overview of pressure coefficient data and the extent to which they are currently implemented in BES–AFN programs. A distinction is made between primary sources of C_p data, such as full-scale measurements, reduced-scale measurements in wind tunnels and computational fluid dynamics (CFD) simulations, and secondary sources, such as databases and analytical models. The comparison between data from secondary sources implemented in BES–AFN programs shows that the C_p values are quite different depending on the source adopted. The two influencing parameters for which these differences are most pronounced are the position on the facade and the degree of exposure/sheltering. The comparison of C_p data from different sources for sheltered buildings shows the largest differences, and data from different sources even present different trends. The paper concludes that quantification of the uncertainty related to such data sources is required to guide future improvements in C_p implementation in BES–AFN programs.