置换通风和冷却顶板复合系统能耗分析研究

为了评价置换通风和冷却顶板复合系统性能及节能潜力，应用Energy Plus软件分别模拟了我国六个典型城市中采用不同除湿方式的置换通风和冷却顶板复合系统及带热回收装置的定风量系统供冷季的能耗进行对比分析。结果表明：置换通风和冷却顶板复合系统采用转轮除湿方式时总能源费用与冷却除湿方式相当;置换通风和冷却顶板复合系统可比定风量系统节约15%以上的运行费用，节能潜力因地区气候和能源价格而异。     

置换通风与混合送风供冷季运行能耗比较

根据置换通风和混合送风设计及运行的特点，以DeST为模拟工具，分析了北京某写字楼分别采用置换通风和混合送风方式供冷季空调系统的运行情况，讨论了两种送风方式在定风量或变风量运行时系统的逐时能耗及在室外新风利用上的特点。结果表明，置换通风比混合送风节省10％以上的运行费用。     

地板个性化送风系统动态能耗分析

地板个性化送风能够改善工作区微环境的空气品质和热舒适性,其送风温度较传统空调系统高,有较大的节能潜力。对送风采用冷冻除湿和转轮除湿时,节能与否或者节能程度大小分别取决于再热量和再生热量及再生风机能耗。本文中,利用能耗模拟分析软件Energyplus分别模拟计算了在中国各气候区使用混合通风、冷冻除湿的地板个性化送风及转轮除湿的地板个性化送风系统时,各系统的年能耗,并进行了比较分析,得出地板个性化送风系统在中国各气候区的能耗特性。     

基于Cromer循环转轮除湿复合空调系统的性能分析

Cromer循环转轮除湿复合空调系统将转轮除湿与表冷器冷却除湿有机地结合起来,转轮除湿实现系统内部的水分转移,表冷器的冷却除湿把全部湿负荷排到外部环境。本文介绍了Cromer循环转轮除湿复合空调系统的工作原理及特点,给出了其与直接冷却除湿处理新风的比较实例。结果表明,在相同供冷水温度下,该复合空调系统能比直接冷却除湿系统实现更低的送风露点温度,提高表冷器的除湿能力;考虑低温新风可以承担室内显热冷负荷,二种新风处理方法对总的节能性没有影响,但前者送风温度接近13℃且低湿,送风品质更高。该方法可以改善室内空气品质,与直接冷却除湿方法相比不增加制冷能耗,且切实可行,值得进一步研究推广。     

不同末端形式下双冷源辐射空调系统模拟研究

本文采用EnergyPlus能耗模拟软件,以上海市某别墅为建筑对象,对顶板/墙面辐射+置换通风两种不同双冷源空调系统进行设计工况下的热舒适和能耗模拟分析,同时与VRV空调系统的模拟结果进行对比。结果表明:与VRV系统相比,墙面辐射双冷源空调系统具有更好的热舒适性、更低的能耗。达到相同的热舒适度标准,所用时间更少。全年供冷主机能耗可节约50%,供热主机能耗可节约23%。     

地板辐射供冷-置换通风的实验研究

为了研究地板辐射供冷的热工性能,测试了北京地区不同室外气温下地板辐射供冷系统的运行工况,得到了该系统的制冷量,地板表面温度,室内温度场分布等参数,并且把单独地板辐射供冷系统的运行参数与地板辐射供冷-置换通风复合式系统进行了对比,提出了将地板辐射供冷与置换通风配合用于夏季空调室内供冷除湿的新型空调方式,置换通风系统在近地面处形成干燥空气层,可有效防止夏季热湿天气在地板表面出现结露现象,并且使这种新型空调系统条件下地面与室内的换热得到强化.通过理论分析和实验研究指出这是一种舒适、节能的空调方式.     

转轮除湿与单元式空调机相结合的空气处理系统

本文介绍了转轮除湿与直接膨胀式单元机组相结合的复合空调系统的2种紧凑型组成形式:前置预冷与后置冷却,并在几种不同室外工况下,针对应用于独立新风系统,对比分析了这2种典型组成方案的性能特点。结果表明,这2种除湿方式在4种典型工况下的制冷能耗相差不明显,在10%以内;但后置冷却除湿在高温高湿工况下难以实现较大的单位除湿量,且再生空气温度高;而前置预冷除湿系统采用较小的除湿转轮尺寸,结构更紧凑,可明显降低初投资,且再生空气温度较低。因此,前置预冷除湿系统在较小流量空气处理应用方面更具优势,更具商品化发展潜力。     

不同除湿方式户式辐射空调系统能耗研究

模拟比较了冷水式除湿、制冷剂直膨式除湿、双冷源除湿3种除湿方式下户式辐射空调系统的夏季供冷能耗。结果显示:3种除湿方式下,空调房间温度均能满足要求,采用制冷剂直膨式除湿时室内温度略低,双冷源除湿时室内温度略高;采用制冷剂直膨式除湿的户式辐射空调系统能耗最低,冷水式除湿能耗最高,直膨式除湿的能耗较冷水式除湿约低15%,较双冷源除湿约低10%。     

顶板辐射供冷与置换通风的实验研究

顶板辐射供冷是一种舒适度较高的空调方式,系统的供冷能力和顶板表面温度是系统设计和运行的重要参数.实际工程运行参数及其影响因素的测试分析十分必要.本文通过实验测试研究找出影响顶板换热的主要因素,分析了置换通风下的顶板结露问题,提出了将顶板辐射供冷与置换通风配合用于夏季室内供冷除湿的新型空调方式.研究结果可为实际工程的设计、运行参数的选择和系统的可行性分析提供依据和指导.     

某辐射空调工程设计与应用研究

本文以南京某会所空调系统为例,介绍了顶棚辐射板供冷(暖)和转轮除湿新风机组相结合的空调系统设计方案,顶棚辐射板供冷(暖)系统的特点及安装方式、转轮除湿新风机组、空调冷热源系统及温湿度独立控制系统的设计要点。     

Comparison of annual energy performances with different ventilation methods for temperature and humidity control

Stratum ventilation has been proposed to accommodate elevated indoor temperatures recommended by governments in East Asia. TRNSYS is used for computation of the space cooling loads, sensible and latent, as well as system energy consumption. Typical configurations of an office, a classroom and a retail shop in Hong Kong are investigated. Desiccant dehumidification with and without solar assistance is utilized for the air treatment under displacement ventilation and stratum ventilation, while simple reheating is adopted under mixed ventilation. Compared with mixing ventilation and displacement ventilation, stratum ventilation derives its energy saving potential largely from the following five factors: the reduction in ventilation, dehumidification and transmission loads, prolonged free cooling period and increased the COP of the chillers. For the office, the year-round energy saving is found to be substantial at 20% and 40% without the need for solar energy provision when compared with displacement ventilation and mixing ventilation respectively. For the classroom and retail shop, the year-round energy saving is at about 25% and at least 37% with the aid of solar energy provision when compared with displacement ventilation and mixing ventilation respectively.     

Energy analysis for workshops with floor–supply displacement ventilation under the U.S. climates

Many studies have shown that floor–supply displacement ventilation systems are better than mixing ventilation systems. The benefits include indoor air quality, thermal comfort and reduced energy use. The energy benefits depend on the climate conditions. This research compared the energy use of a floor–supply displacement ventilation system in a large industrial workshop with that of a mixing ventilation system for five U.S. climate regions. It was found that the energy use and the system performance vary with the locations. The displacement ventilation system may use more fan and boiler energy but less chiller energy than the mixing ventilation system. The total energy used is slightly less with displacement ventilation, although the ventilation rate was increased in order to handle the high cooling loads found in U.S. buildings. Thus, the displacement ventilation system can save some energy in cooling mode. However, displacement ventilation system has a lower capacity of dehumidification. This system alone, thus, is not suggested for use in humid regions.     

转轮除湿用于冷却顶板空调系统的探讨

通过理论计算分析,发现在低温环境下冷却去湿与冷却顶板结合的空调系统存在机器露点过低和需要较大再热量的不利因素,但把转轮除湿与冷却顶板空调系统相结合则不仅可以克服这些不利因素,还可以降低能耗,节省运行费用,增强冷却顶板空调系统节能效果、提高湿度控制精度。     

Energy savings potential of a desiccant assisted hybrid air source heat pump system for residential building in hot summer and cold winter zone in China

In hot summer and cold winter zone in China, air conditioning system has four running modes yearly including cooling with dehumidification, cooling, dehumidification and heating in residential buildings. The conventional air source heat pump (ASHP) system is not designed to independently control temperature and humidity, and is not very suitable for the dehumidification mode in the view of building energy consumption. A novel ASHP system combining radiant cooling/heating for residential buildings was presented. The main feature of this hybrid ASHP system is that desiccant wheel and cooling coil accomplish dehumidification process together, and the regenerative heat needed by the desiccant wheel is supplied by the condenser dissipated heat. Based on simulation studies and performance analysis, this paper predicts the primary energy consumption of the hybrid ASHP system in comparison with the conventional ASHP system during the cooling and heating seasons. It was found that primary energy requirement can be reduced by more than 8% in cooling with dehumidification mode, by 50% in dehumidification mode, and by more than 14% in heating mode. The study results prove that the hybrid ASHP system can keep great energy saving and running cost saving yearly, especially in the dehumidification process.     

A combined system of chilled ceiling,displacement ventilation and desiccant dehumidification

Different types of heating, ventilation, and air-conditioning (HVAC) systems consume different amounts of energy yet they deliver similar levels of acceptable indoor air quality (IAQ) and thermal comfort. It is desirable to provide buildings with an optimal HVAC system to create the best IAQ and thermal comfort with minimum energy consumption. In this paper, a combined system of chilled ceiling, displacement ventilation and desiccant dehumidification is designed and applied for space conditioning in a hot and humid climate. IAQ, thermal comfort, and energy saving potential of the combined system are estimated using a mathematical model of the system described in this paper. To confirm the feasibility of the combined system in a hot and humid climate, like China, and to evaluate the system performance, the mathematical model simulates an office building in Beijing and estimates IAQ, thermal comfort and energy consumption. We conclude that in comparison with a conventional all-air system the combined system saves 8.2% of total primary energy consumption in addition to achieving better IAQ and thermal comfort. Chilled ceiling, displacement ventilation and desiccant dehumidification respond consistently to cooling source demand and complement each other on indoor comfort and air quality. It is feasible to combine the three technologies for space conditioning of office building in a hot and humid climate.     

液体除湿的经济性分析

介绍了液体除湿系统的原理，比较了液体除湿与冷冻除湿系统的初投资，认为液体除湿是一种经济节能的空调方式。     

Performance of combined displacement ventilation and cooled ceiling liquid desiccant membrane system in Beirut climate

The performance of the chilled ceiling (CC) displacement ventilation (DV) systems is constrained by latent load removal capacity and cost of supply air dehumidification to prevent condensation on the ceiling. In this study, a liquid desiccant dehumidification membrane cycle (LDMC) is mathematically modelled to replace the CC and remove directly latent and sensible load from indoor space through the membrane. The desiccant system is coupled with the DV system. An optimized operational strategy is adopted while allowing ceiling temperature to drop to lower values than conventional CC/DV. The optimized LDMC-C/DV system was implemented in an office space in Beirut climate. It was found that decreasing the membrane liquid desiccant temperature resulted in a significant decrease in the total cooling energy of the system, while increasing the solar heating energy of the desiccant regeneration. At optimal set points, a decrease of 49% in energy consumption was observed compared to the conventional CC/DV system.     

Ceiling mounted personalized ventilation system in hot and humid climate—An energy analysis

This study is to evaluate energy saving potential of ceiling mounted personalized ventilation (PV) system in conjunction with background mixing ventilation compared with mixing ventilation system alone and with mixing ventilation system when occupants are provided with individually controlled desk fans for generating additional air movement at each desk. Control strategy applied includes different number of personalized ventilation air terminal devices used and different PV airflow rates supplied. Energy calculation is based on design conditions in Singapore, representing a hot and humid climate. The results reveal that increasing room temperature can save cooling energy when the combination of PV with ceiling mounted personalized ventilation nozzles and background mixing ventilation is used. In this case the energy for transport of air increases but the total energy decreases, i.e. energy can be saved due to elevated room temperature. Comparing with mixing ventilation plus desk fans, ceiling mounted personalized ventilation cannot only realize better cooling effect but also decrease the total energy consumption.     

转轮除湿复合式空调系统

介绍了转轮除湿与常规冷却及蒸发冷却相结合的两类复合式空调系统。指出了在要求低湿或湿负荷较大的场合,采用前者既可避免制冷机的蒸发温度过低影响制冷效率,又可避免凝结水排放不当造成渗漏等问题,利于节能;采用后者,节能效果更显著,而且既无ＣＦＣ问题,又能缓解夏季电力供应紧张的压力。