An optimal control algorithm for borehole thermal energy storage systems

The aim of this paper is to present an optimal control algorithm to manage borehole thermal energy storage systems (BTES). Such a system gets exhausted, if it is employed intensively, i.e. outlet fluid is outside acceptable temperature ranges, and can no longer provide the desired heat or cold. To avoid this problem a control algorithm is proposed, which simultaneously optimizes the operation costs. This algorithm is based on a dynamic programming technique and results in an array which provides the optimal heat flux for a given field temperature, date and demand. The controller is illustrated on a simulation of an existing building. Several weather scenarios have been examined and the system remained robust under all situations.     

季节性含水层储能系统在住宅中的应用

提出一种含水层储能的住宅集中空调系统。在分析含水层储能的数学模型及其离散算法的基础上，编制了计算机模拟程序，利用该程序对影响含水层储能效果的若干因素进行了模拟计算，认为集中回灌比分散回灌效果好；在回灌热量一定的情况下，小流量大温差运行效果较好；地质条件对系统热效率和抽水温差有影响。     

北京市蓄能用电工程热工性能测试与分析

对北京地区已经运行的典型蓄能用电工程冬夏季工况分别进行了测试、评定,同时结合调研数据及客户反映意见,对电蓄冷(热)技术应用中存在的主要问题进行了分析研究,给出了相应对策,为今后加强对北京地区蓄能用电工程的科学管理水平,提高工程评价的准确性、可靠性提供了基础条件。     

An aquifer thermal storage system in a Belgian hospital: Long-term experimental evaluation of energy and cost savings

Over a three years period, an aquifer thermal energy storage system was monitored in combination with a heat pump for heating and cooling of the ventilation air in a Belgian hospital. The installation was one of the first and largest ground source heat pump systems in Belgium. Groundwater flows and temperatures were monitored as well as the energy flows of the heat pumps and the energy demand of the building. The resulting energy balance of the building showed that the primary energy consumption of the heat pump system is 71% lower in comparison with a reference installation based on common gas-fired boilers and water cooling machines. This corresponds to a CO₂-reduction of 1280 ton over the whole measuring period. The overall seasonal performance factor (SPF) for heating was 5.9 while the ATES system delivered cooling at an efficiency factor of 26.1. Furthermore, the economic analysis showed an annual cost reduction of k€ 54 as compared to the reference installation, resulting in a simple payback time of 8.4 years, excluding subsidies.     

Performance study of underground thermal storage in a solar-ground coupled heat pump system for residential buildings

This paper is performed to analyze the performance of underground thermal storage in a solar-ground coupled heat pump system (SGCHPS) for residential building. Based on the experimental results, the system performance during a longer period is simulated by the unit modeling, and its parametric effects are discussed. The results show that the performance of underground thermal storage of SGCHPS depends strongly on the intensity of solar radiation and the matching between the water tank volume and the area of solar collectors. Compared with the solar radiation, the variations of the water tank temperature and the ground temperature rise lag behind and keep several peaks during the day time. For the case of Tianjin, the efficiency of underground thermal storage based on the total solar radiation and absorbed solar energy by the collectors can reach over 40% and 70%, respectively. It is suggested that the reasonable ratio between the tank volume and the area of solar collectors should be in the range of 20–40 L/m².     

相变储能微胶囊的制备和表征

以石蜡为囊芯,脲醛树脂为囊壁,采用原位聚合法制备具有相变储能功能的微胶囊,并研究了乳化剂、芯壁质量比以及搅拌速度等对微胶囊制备和性能的影响.结果表明,以司班-80和吐温-80复配作为乳化剂、用量为石蜡的8%,芯壁质量比为1.2:1,转速为1500r/min时,制备的微胶囊性能较好.研究表明,脲醛树脂可有效包覆石蜡,形成粒径分布较均匀的相变储能微胶囊,可用于制备储能建筑材料.     

Selection of micro turbines to meet electrical and thermal energy needs of residential buildings in Iran

Micro gas turbines are considered to meet the electrical, domestic hot water, heating and cooling energy needs of a residential building located in Tehran, Ahvaz and Hamedan. The building is 10 stories high and has a total of 8000 m² floor area with the peak demands of electricity of 32.96 kW, DHW of 0.926 kW, heating load of 1590 kW and the cooling load of 2028 kW, when the building is located in Tehran. With these demands, 30 micro turbines of 30 kW (nominal power) are needed to meet all the energy needs of the building. The excess electricity generated by the micro turbines is to be used in a heat pump, and the energy in the exhaust gases is to be used to meet other thermal energy needs of the building. With proper energy conservation measures and the use of ceiling fans in each room, the peak heating and cooling demands of the building were reduced to 225 kW and 760 kW, respectively. With these measures, two micro gas turbines of 30 kW nominal capacity, or one of 40 kW, could meet all the electrical, DHW, heating and a great portion of the cooling needs of the building. The remaining cooling needs of the building during the hot hours of summer could be met by an additional absorption refrigeration, utilizing natural gas as its energy source. It is recommended that with energy conservation measures, the heating and cooling loads of buildings be reduced as much as possible, and micro gas turbines be employed to meet the electrical demands and a portion of heating and cooling needs. The remaining thermal energy needs are to be met through the use of natural gas. Only with these measures, the on-site combined heat and power (OS-CHP) is a viable option for residential buildings in Iran.     

Economic feasibility of thermal energy storage systems

This paper investigates the economic feasibility of both building an ice thermal storage and structure a time of rate tariff for the unique air conditioning (A/C) plant of the Grand Holy Mosque of Makkah, Saudi Arabia. The features of the building are unique where the air-conditioned 39,300 m² zone is open to the atmosphere and the worshippers fully occupy the building five times a day, in addition hundreds of thousands of worshippers attend the blessed weekend's prayer at noontime, which escalates the peak electricity load.     

Battery energy storage systems: Assessment for small-scale renewable energy integration

Concerns arising due to the variability and intermittency of renewable energy sources while integrating with the power grid can be mitigated to an extent by incorporating a storage element within the renewable energy harnessing system. Thus, battery energy storage systems (BESS) are likely to have a significant impact in the small-scale integration of renewable energy sources into commercial building and residential dwelling. These storage technologies not only enable improvements in consumption levels from renewable energy sources but also provide a range of technical and monetary benefits. This paper provides a modelling framework to be able to quantify the associated benefits of renewable resource integration followed by an overview of various small-scale energy storage technologies. A simple, practical and comprehensive assessment of battery energy storage technologies for small-scale renewable applications based on their technical merit and economic feasibility is presented. Software such as Simulink and HOMER provides the platforms for technical and economic assessments of the battery technologies respectively.     

储能电站用锂离子电池热失控早期预警参数研究

讨论储能用磷酸铁锂电池在过充条件下的电压、表面温度以及所释放特征气体浓度特征参数变化规律,分析热失控机理、发展过程和早期预警阈值。实验结果表明：过充可促发电池内部一系列放热化学反应,引起温度、电压升高并伴有大量可燃气体产生,其中H2 含量最高且最先被气体探测器感知;电池电压、表面温度和H2 质量浓度特征参数建议报警范围分别为：4.8～6.6V、60～116 ℃、20～50 mg/L。     

蓄热在空调系统中的应用

结合工程实例，介绍了电蓄热空调系统的设计方法，分析了电蓄热空调系统的优缺点，指出了采用电蓄热应注意的问题。     

相变蓄能建筑材料的发展

首先总结了近几年建筑节能中相变蓄能技术的研究进展,然后对相变蓄能建筑材料的制备技术和研究方法等进行了概述,并对相变蓄能建筑材料在多功能墙体或地板、智能控温建筑物或混凝土工程及太阳能建筑等方面的应用前景进行了展望,以促进相变蓄能建筑材料的发展。     

蓄冷空调系统的负荷计算

分析了常规空调系统和蓄冷空调系统负荷计算的不同及逐时负荷分布对蓄冷系统负荷计算的重要性，指出了在蓄冷系统负荷计算时应该注意的问题。     

相变蓄能建筑材料的研究与发展

相变材料可以与传统建材复合成具有蓄热和调温功能的新型建筑材料.总结相变材料在建筑中的研究与发展情况,介绍相变蓄能材料的选择标准和复合工艺,简要分析相变材料的主要性质,并对相变蓄能建筑材料今后的研究和发展进行探讨.     

间接式水合物蓄冷装置中传热传质过程分析

分析了间接接触式水合物蓄冷实验装置的传热及传质过程,指出冷凝器的冷凝传热、氟利昂液体的蒸发及水合反应是耦合过程,而强化气层的冷凝传热、采用表面活性添加剂以减小气泡直径是加快水合速率、提高蓄冷密度的关键。     

光伏光热建筑一体化对建筑节能影响的理论研究

对光伏光热建筑一体化(BIPV／T)的两种主要模式建立了理论模型，采用香港地区典型年的气象数据对两种BIPV／T模式的热性能进行了计算分析。与常规建筑相比，光伏光热建筑减少了墙体得热，改善了室内空调负荷状况，提高了建筑节能效果。     

空气源热泵相变蓄能除霜方式的实验研究

以目前广泛使用的空气源热泵分体式房间空调器为研究对象,建立了空气源热泵相变蓄热逆循环除霜系统的动态实验台,对系统运行中的结霜过程进行描述,并对空气源热泵与蓄热器之间不同连接方式的除霜情况进行比较分析,总结得出了性能较高的蓄能除霜方式。     

寒冷地区乡村住宅保温节能技术研究

针对我国北方寒冷地区居住热环境的情况对北方农村住宅围护结构中的外墙及门窗，屋面，地面和建筑设计等方面，提出了２６项节能技术。     

地源热泵结合水蓄能系统应用分析

以某工程案例介绍了常规冷水机组、地源热泵机组与水蓄冷、蓄热系统的结合应用。通过系统初投资及运行费用的分析,结合空调系统的稳定性、灵活性、实用性,指出了地源热泵与水蓄能系统的应用前景。     

Personal heating: effectiveness and energy use

Buildings use approximately 40% of primary energy with most energy expended on the provision of a comfortable indoor climate. An extended range of indoor temperatures can significantly reduce the energy load. However, lower temperature set points for heating can cause thermal discomfort. Giving building occupants the option to warm themselves (e.g. a local source at their desk or workstation) can mitigate this discomfort by the provision of a personalized conditioning system. A model is presented to assess the performance of personalized heating and its impact on the whole building energy load. Researchers, designers and facility managers can use this model to compare performance and analyse energy savings. The total energy use of personalized heating is estimated by scaling its settings to the actual level of discomfort resulting from a lowered heating set point. This model is used to assess seven different personalized heating systems. Assessments reveal that personalized heating brings a remarkable energy-saving potential, while maintaining or even improving individually perceived thermal comfort. Assessments are based on an assumed linear relation between the power and level of increased thermal sensation. Future research in personalized conditioning systems should be directed towards the development of the full characteristics and specific settings.