空调工程中的蓄冷技术

本讲介绍了空调工程中实用的七种蓄冷系统，论述了各种系统的形式及主要特征，分析了每种系统的优缺点。这七种系统包括：冷媒盘管式蓄冷系统、完全冻结式蓄冷系统、冰球式蓄冷系统、制冰滑落式蓄冷系统、冰晶式蓄冷系统、水蓄冷系统和共晶盐蓄冷系统。     

空调工程中的蓄冷技术：第一讲 蓄冷技术概述

这一讲介绍了蓄冷技术在我中发展的社会背景及蓄冷技术发展的历史和国内外发展概况；阐述了蓄冷的含义、蓄冷系统的分类以及全部蓄冷与部分蓄冷两种设计模式；此外，分析了空调系统中采用蓄冷技术的优缺点并指出了蓄冷系统的适用场所。     

蓄冷量比例对设备投资及运行电费的影响

以深圳市某冰蓄冷工程设计参数为依据，比较了不同蓄冷量下的蓄冷空调和常规空调系统机房主要设备初投资和年运行电费，给出了适宜的蓄冷量比例范围。     

冰蓄冷空调讲座之（4）空调工程中的蓄冷技术第四讲 蓄冷空调系统的初步…

介绍了蓄冷空调系统的初步设计方法，给出了蓄冷空调系统的冷负荷、制冷机容量及蓄冷量的估算方法，最后简要介绍了蓄冷空调系统的经济评价方法。     

并联冰盘管蓄冷装置设计方法探讨

在研究并联冰盘管蓄冷装置制冰、融冰特性的基础上，讨论了包括确定蓄冰槽容积、蓄冰量，盘管长度，盘管排列方式等内容的设计方法。认为这一探讨有益于冰蓄冷装置的系列化设计及系统的控制运行。     

空调相变蓄冷技术的研究进展

本文阐述了纳米流体、微胶囊及定形相变材料等新型相变材料的研究现状,以及相变材料在空调蓄冷系统中的应用,归纳出了相变过程的一般规律和特殊性问题,对蓄冷设备的蓄冷量、蓄冷速率等参数的影响因素展开了分析,并对混合蓄冷、相变蓄冷型太阳能空调系统以及相变蓄冷型潜热输送空调系统等新型空调蓄冷系统进行了介绍和评价.相变蓄冷材料有着适宜的相变温度和较高的蓄冷密度,应用于空调蓄冷系统可提高制冷机效率,对于建筑节能具有重要意义.     

冰蓄冷空调讲座之（5）：空调工程中的蓄冷技术──第五讲 蓄冷空调工程实例简介

简要介绍了采用不同蓄冷方式的几个蓄冷空调工程实例，并侧重分析了投资及能耗问题。对蓄冷系统的选用及蓄冷空调工程设计均有参考价值。     

大过冷度制冷—高温水蓄冷空调系统研究

阐述了大过冷度制冷-高温水蓄冷空调系统原理，对该新型蓄冷空调系统若干方案进行了选择，特别是对蓄冷水箱的掺混度进行了研究，建立了空调用蓄冷水箱内温度分层特性数理模型，模拟了蓄冷水箱内温度分布规律，并与实验值进行了比较，两基本吻合，该模型可为水蓄冷系统储水箱的设计和运行提供理论依据。     

蓄冷技术及其应用现状

本文介绍了蓄冷方式和特点，并对蓄冷水和蓄冰的应用条件进行了比较，指出了蓄冷技术的应用领域，介绍了蓄冷技术在国内外的应用现状及目前研究的主要问题。     

也谈最佳蓄冷率的确定方法

文献［１］中作者介绍了求取最佳蓄冷率的方法，但该方法忽视了最佳蓄冷率的约束范围，本文拟进行说明。在冰蓄冷空调系统中，控制策略不论是采取制冷机组优先，还是释冷优先，其蓄冷率的确定都必须满足这样一个条件，即在满足建筑物设计日冷负荷的同时，必须保证在该蓄冷...     

Thermoaktive Bauteilsysteme mit integrierten Phasenwechselmaterialien – eine Simulationsstudie

Thermo‐active building systems using phase‐change materials – a simulation study. The objective of this study aims at analyzing and evaluating thermo‐active building systems as well as a night ventilation concept with respect to thermal interior comfort by means of a simulation study. Preliminary experiments in a low‐energy office building facilitate the calibration of the simulation model in ESP‐r. In particular, the analysis was carried out for (i) concrete core conditioning, (ii) grid conditioning without and (iii) with 20% of micro‐encapsulated latent heat storage materials (PCM) applied to the ceiling. The central conclusions of this study are: (1) Grid conditioning provides a satisfactory room condition comparable with concrete core conditioning, (2) the application of PCM contributes to a reduced operative room temperature, and (3) in this study PCM with a melting range of 19 to 22 °C is most favorable.     

Effect of double layer phase change material in building roof for year round thermal management

Efficient and economical technology that can be used to store large amounts of heat or cold in a definite volume is the subject of research for a long time. Latent heat storage in a phase change material (PCM) is very attractive because of its high-energy storage density and its isothermal behavior during the phase change process. Thermal storage plays a major role in building energy conservation, which is greatly assisted by the incorporation of latent heat storage in building products. Increasing the thermal storage capacity of a building can enhance human comfort by decreasing the frequency of internal air temperature swings so that the indoor air temperature is closer to the desired temperature for a longer period of time. However, it is impossible to select a phase change material to suit all the weather condition in a given location. The PCM that reduces the internal air temperature swing during the winter season is not suitable for the summer season as the PCM remains in the liquid state at all the times during these months and hence the system cannot exploit the latent heat effect. This paper attempts to study the thermal performance of an inorganic eutectic PCM based thermal storage system for thermal management in a residential building. The system has been analyzed by theoretical and experimental investigation. A double layer PCM concept is studied in detail to achieve year round thermal management in a passive manner.     

Numerical and experimental study on heat pump water heater with PCM for thermal storage

An air source heat pump water heater with phase change material (PCM) for thermal storage was designed to take advantage of off-peak electrical energy. The heat transfer model of PCM was based upon a pure conduction formulation. Quasi-steady state method was used to calculate the temperature distribution and phase front location of PCM during thermal storage process. Temperature and thermal resistance iteration approach has been developed for the analysis of temperature variation of heat transfer fluid (HTF) and phase front location of PCM during thermal release process. To test the physical validity of the calculational results, experimental studies about storing heat and releasing heat of PCM were carried. Comparison between the calculational results and the experimental data shows good agreement. Graphical results including system pressure and input power of heat pump, time-wise variation of stored and released thermal energy of PCM were presented and discussed.     

Enhancement of solar thermal energy storage performance using sodium thiosulfate pentahydrate of a conventional solar water-heating system

The time variations of the water temperatures at the midpoint of the heat storage tank and at the outlet of the collector in a conventional open-loop passive solar water-heating system combined with sodium thiosulfate pentahydrate-phase change material (PCM) were experimentally investigated during November and then enhancement of solar thermal energy storage performance of the system by comparing with those of conventional system including no PCM was observed. It was observed that the water temperature at the midpoint of the storage tank decreased regularly by day until the phase-change temperature of PCM after the intensity of solar radiation decreased and then it was a constant value of 45 °C in a time period of approximately 10 h during the night until the sun shines because no hot water is used. Heat storage performances of the same solar water-heating system combined with the other salt hydrates-PCMs such as zinc nitrate hexahydrate, disodium hydrogen phosphate dodecahydrate, calcium chloride hexahydrate and sodium sulfate decahydrate (Glauber's salt) were examined theoretically by using meteorological data and thermophysical properties of PCMs with some assumptions. It was obtained that the storage time of hot water, the produced hot water mass and total heat accumulated in the solar water-heating system having the heat storage tank combined with PCM were approximately 2.59–3.45 times of that in the conventional solar water-heating system. It was also found that the hydrated salts of the highest solar thermal energy storage performance in PCMs used in theoretical investigation were disodium hydrogen phosphate dodecahydrate and sodium sulfate decahydrate.     

相变通风屋顶的供热节能优化设计研究

提出太阳能相变屋顶系统(主要由太阳能空气集热系统、相变通风屋顶组成),将两种相变材料(PCM1、PCM2,PCM1用于供冷期蓄冷,相变温度在35℃左右。PCM2用于供暖期蓄热,相变温度在18℃左右)及风道(预制在钢筋混凝土板内,供冷期利用夜间低温空气冷却屋顶与PCM1,供暖期利用太阳能空气集热器出口热空气加热屋顶与PCM2)预制在屋顶内,形成相变通风屋顶(由上至下的基本结构为保护层、防水层、找坡层、保温层、找平层、PCM1、钢筋混凝土板),实现供冷期夜间蓄冷日间吸热、供暖期日间蓄热夜间放热。针对供暖工况,采用模拟方法,结合评价指标,对相变通风屋顶中相变材料(由于供暖工况PCM1不发生相变,因此研究对象为相变材料PCM2)的相变温度、结构(即相变材料位置)、相变材料厚度进行优化选取。A型相变通风屋顶将PCM2设置在PCM1与钢筋混凝土板之间,B型相变通风屋顶将PCM2设置在钢筋混凝土板下面,C型相变通风屋顶将PCM2设置在预制风道外圈。PCM2的最佳相变温度为18~20℃,最优结构为B型相变通风屋顶,PCM2最佳厚度为30 mm。与无相变通风屋顶(将B型相变通风屋顶中的30 mm厚PCM2相变材料替换成相同厚度的水泥砂浆,保留预制风道,其他各层材料及厚度均保持不变)相比,最佳相变通风屋顶(PCM2相变温度为18~20℃、厚度为30 mm的B型相变通风屋顶)的各项评价指标均更优。     

Modeling of an integrated solar system

The feasibility of using low-cost solar collection and storage technology to provide energy for residential units is investigated. Different construction strategies were compared including traditional housing practice against newly innovative ideas such as low radiant heating system, desiccant dehumidification, integrated low-cost solar collection, and phase-change material (PCM) storage. The selected building, located in Blacksburg, VA, integrated a solar thermal roof collection system consisting of a low-temperature flat-plate collector integrated within a concrete building envelope linked to a PCM storage tank. For the considered location and weather conditions (Blacksburg, VA), the proposed collection and storage solar system can supply 88% of the building's space heating and hot water needs averaged throughout the year saving the homeowner approximately 61.5% of the annual heating bills. However, the use of a storage system is not economical for the considered conditions. The paper also shows a month-by-month demand and supply distributions for the modeled building's heating and hot water needs.     

相变材料的研究进展与应用综述

相变材料在蓄热方面具有单体蓄能高、蓄能过程等温发生等优势,通过归纳各类常见相变材料的优缺点,探讨了作为良好相变材料应具有的热物理特性,同时,通过对相变材料在生产和生活中应用的介绍,总结了相变材料在当前应用中存在的问题,且对其未来的发展趋势提出展望。     

Dynamic performances of solar heat storage system with packed bed using myristic acid as phase change material

This paper is aimed at analyzing the thermal characteristics of packed bed containing spherical capsules, used in a latent heat thermal storage system with a solar heating collector. Myristic acid is selected as phase change material (PCM), and water is used as heat transfer fluid (HTF). The mathematical model based on the energy balance of HTF and PCM is developed to calculate the temperatures of PCM and HTF, solid fraction and heat release rate during the solidifying process. The latent efficiency, which is defined as the ratio between the instantaneous released latent heat and the maximum released heat, is introduced to indicate the thermal performances of the system. The inlet temperature of HTF (50 °C), flow rate of HTF (10 kg/min) and initial temperature of HTF (66 °C) were chosen for studying thermal performances in solar heat storage system. The influences of inlet temperature of HTF, flow rate of HTF and initial temperatures of HTF and PCM on the latent efficiency and heat release rate are also analyzed and discussed.     

相变储热轻质围护结构夏季隔热节能的实验研究

采用复合相变材料和聚苯乙烯泡沫板制成了轻质板结构,克服了轻质材料墙体储热能力差的缺陷.在重庆地区对该复合板作围护结构的轻质实验房夏季炎热环境下的隔热及空调节能进行了实验研究,结果表明该相变材料轻质墙体能够有效地利用昼夜温差储放热,有效地阻止热量进入室内,非空调工况下可明显降低室内温度,具有较好的节电效果.     

Monitoring results of an interior sun protection system with integrated latent heat storage

An interior sun protection system consisting of vertical slats filled with phase change material (PCM) was monitored from winter 2008 until summer 2010. While conventional interior sun protection systems often heat up to temperatures of 40 °C or more, the monitoring results show that the surface temperature on the interior side of the PCM-filled slats hardly ever exceeded the PCM melting temperature of 28 °C even in case of long-term intense solar radiation. As long as the PCM is not fully melted, the latent heat storage effect reduces the solar heat gain coefficient (g-value) of the sun protection system to 0.25 for a totally closed blind, and 0.30 for slats set at 45° (the g-values of the same system without PCM are 0.35 and 0.41, respectively). This reduced the maximum air temperature in the offices by up to 2 K in contrast to a reference room with a comparable conventional blind. The sun protection system with PCM therefore considerably improves thermal comfort. In order to discharge the PCM, the stored heat must be dissipated during the night. In climates with sufficiently low outside air temperatures, this is best achieved using a ventilation system in combination with tilted windows.