长途客车中的空气品质和人体热舒适研究

就送，回风口设置对长途客车中空气品质和人体热舒适的影响进行了数值模拟分析。文中采用olf（污染源强度）和decipol（空气品质感知值）作为评价空气品质的指标，借助于流场计算的PHOENICS软件。模拟分析了在冬、夏季工况下，采用不同的送、回风口位置的组合形式时，客车内速度场、温度场和浓度场的分布倩况，研究结果从满足室内空气品质和人体热舒适的角度给出了冬、夏季工况下宜采用的气流组织形式。     

气流组织对空调房间空气环境影响的数值模拟

针时相同室内条件、不同气流组织形式下的各种模型,运用暖通空调专用数值模拟软件Airpark,对室内速度场、温度场进行了数值模拟计算.并应用模拟结果分析不同气流组织形式下的空气品质和人体热舒适,为空调室内的气流组织形式优化设计及舒适性提供了研究依据.     

会议室空调气流组织的数值模拟研究

利用Airpak软件对夏季使用落地式空调器制冷的某会议室气流组织进行数值模拟,研究了空调器位置设置不同对室内热舒适的影响,得到不同室内气流组织下速度场与温度场的分布,采用PMVPPD与空气龄指标对室内人员的热舒适性与空气品质进行评价。模拟结果表明,在东墙布置落地式空调的方式在改善工作区域空气品质以及人体热舒适性方面均优于南墙,为气流组织优化设计和空调室内热舒适性环境的改善提供了参考。     

置换通风与CFD数值模拟

为了降低空调通风系统的能耗,提高通风效率,改善热舒适性,对于建筑在夏季工况下,可采用置换通风方式来满足室内空气品质和热舒适性的要求.通过分析置换通风的运行原理,借助计算流体力学的理论和方法,利用CFD(Fluent)软件,采用了低Re数湍流模型,模拟了夏季工况下的室内温度场和速度场.     

某报告厅空调系统的设计及其能耗分析

介绍了西安某办公楼报告厅空调系统的设计。分别应用置换通风与混合通风两种通风方式，在室外和室内设计参数相同的情况下，充分比较了它们在送风量、新风量、能耗以及室内空气品质的不同。结果表明在某些应用场合，置换通风在空气品质提高和能耗降低上有明显的优势，同时这种优势不以牺牲热舒适性为代价，因此建议使用置换通风系统。     

室内空气品质与新风节能研究进展

空调系统正由舒适性向健康性发展,在这条必经之路上空气品质、舒适性和节能性三者要齐头并进,缺一不可。关于新风问题、室内空气品质和节能一直是人们关注的室内环境控制的主题。本文强调了空气品质与空气污染的区别,阐述了保证室内一定空气品质的重要性;分析了新风量、新风质量与室内空气品质的关系,并对不合理的新风方式和新风处理引起室内空气品质恶化和空调系统能耗增加做了一定的研究;从新风处理、减少空调系统二次污染、优化气流组织、加强新风调节等方面分析了新风节能的一些措施。最后对新风新技术研究情况进行了一定的介绍。这对提高室内空气品质降低空调系统的能耗具有重要意义。     

上置置换通风-顶板辐射供冷室内热环境研究

利用计算流体力学(CFD)方法,对上置置换通风-顶板辐射供冷复合空调办公建筑室内采用不同气流组织方式的通风效果进行了模拟研究,分析比较了气流组织特性指标--温度不均匀系数k1、速度不均匀系数ku空气分布特性指数ADPI及温度效率ηt等,给出了送、排风口适宜的上置安装位置.并从舒适性、供冷情况、竖直温度梯度以及温度、速度场分布等方面与传统置换通风.顶板辐射供冷复合空调系统进行了比较,指明了这种新型空调模式可行性、优点及不足.     

空调房间气流组织与人体热舒适

介绍了人体热舒适的定义和环境影响因素:空气温度、空气速度、相对湿度和平均辐射温度。分析了气流组织与人体热舒适的关系。以下送风空调为例,阐述了此种空调方式的气流组织形式及其对人体热舒适的影响。     

送风速度对厂房气流组织及烟尘控制的影响

置换通风以其在高大空间的节能、热舒适性及室内空气品质等方面的优越性,在焊接厂房的烟尘治理中得到了广泛的应用。针对指导置换通风的规范标准相对缺乏,详细的工程设计参考数据不足这一问题采用CFD方法研究焊接厂房置换通风的优化设计。影响焊接厂房室内气流组织和空气品质的因素有:送风温度、送风速度、送风筒的安装高度等,其中送风速度对厂房的气流组织和人体舒适性有很大的影响。本文以南车长江车辆有限公司的焊接厂房为例,模拟分析不同的送风速度对焊接厂房内气流组织和污染物浓度分布的影响。     

不同气流组织形式下空气龄的实验研究

空气龄是评价室内空气品质的指标之一,本文利用CO2示踪气体得出了常用的6种气流组织形式下标准气室中各测点处的浓度衰减曲线,并计算出各测点的空气龄。实验可重复性较好,测得的空气龄反映了标准气室各点空气的新鲜程度,描述了不同气流组织形式通风效率的高低,揭示了室内空气的流动形态,也给空调房间气流组织形式的合理选择提供了依据。     

办公室室内空气品质及热舒适模拟

利用CFD软件Airpak,对某办公室在夏季工况下室内空调送风进行数值模拟.根据模拟所得结果分析室内空气品质及热舒适,为空调房间的气流组织形式优化设计及室内热环境的改善提供参考.     

Effect of internal partitions on the performance of under floor air supply ventilation in a typical office environment

This paper presents a case to investigate the effect of partitions in an office on the performance of under floor air supply ventilation system via computational fluid dynamics. The assessment is in terms of thermal comfort and indoor air quality with the use of a validated computer model. The results indicate that the partitions may significantly affect airflow and performance of a under floor air supply ventilation system. In particular, the presence of a gap above the partition wall is able to improve air distribution owing to less air re-circulation in the upper zone. Its effect on thermal comfort and indoor air quality indicators are evaluated.     

Selection of window sizes for optimizing occupational comfort and hygiene based on computational fluid dynamics and neural networks

The present paper presents a novel computational method to optimize window sizes for thermal comfort and indoor air quality in naturally ventilated buildings. The methodology is demonstrated by means of a prototype case, which corresponds to a single-sided naturally ventilated apartment. Initially, the airflow in and around the building is simulated using a Computational Fluid Dynamics model. Local prevailing weather conditions are imposed in the CFD model as inlet boundary conditions. The produced airflow patterns are utilized to predict thermal comfort indices, i.e. the PMV and its modifications for non-air-conditioned buildings, as well as indoor air quality indices, such as ventilation effectiveness based on carbon dioxide and volatile organic compounds removal. Mean values of these indices (output/objective variables) within the occupied zone are calculated for different window sizes (input/design variables), to generate a database of input–output data pairs. The database is then used to train and validate Radial Basis Function Artificial Neural Network input–output “meta-models”. The produced meta-models are used to formulate an optimization problem, which takes into account special constraints recommended by design guidelines. It is concluded that the proposed methodology determines appropriate windows architectural designs for pleasant and healthy indoor environments.     

Ventilation and energy performance of partitioned indoor spaces under mixing and displacement ventilation

Large variation in indoor air quality (IAQ) and thermal comfort can occur in partitioned office spaces due to heterogeneous air mixing. However, few published studies examined IAQ, thermal comfort, and energy performance of partitioned occupied spaces, which are commonly found in today’s buildings. The objective of this study is to evaluate indoor environmental quality and air conditioning performance of a partitioned room under two typical ventilation modes: (1) mixing ventilation and (2) displacement ventilation. For a total of six representative air-conditioning scenarios, three-dimensional computational fluid dynamics (CFD) simulations are performed to examine temperature distribution, ventilation effectiveness, energy consumption, and local thermal comfort for two partitioned spaces. Simulation results indicate that temperature distribution in a partitioned room is a strong function of ventilation strategy (mixing vs. displacement), but marginally affected by diffuser arrangements. Local age-of-air (air freshness) significantly varies with both diffuser arrangement and ventilation strategy. Regarding energy consumption, displacement ventilation can achieve an indoor set-point temperature in the partitioned spaces about two times faster than mixing ventilation. Under mixing ventilation, the time to achieve a set-point temperature was notably reduced when each partitioned space is served by its own diffuser. For the same supply airflow rate, displacement ventilation can generate local draft risk at ankle level, while mixing ventilation may result in a draft sensation in wider areas around an occupant. Overall, the results suggest that mixing ventilation system can save energy if each partitioned zone is served by its own diffuser such as a multi-split air conditioning. However, when multiple partitioned zones are served by only one diffuser, displacement ventilation is more energy-efficient and can achieve higher ventilation effectiveness than mixing ventilation.     

Evaluation of simplified ventilation system with direct air supply through the facade in a school in a cold climate

Many educational buildings in industrialised countries have poor indoor climate, according to today’s knowledge about the impact of indoor climate on well-being and productivity. Budget restrictions and practical limitations such as lack of space for central air handling units and ventilation ducts, have motivated the application of simplified ventilation systems in some schools, such as taking unconditioned supply air directly from the facade. One such school was recently evaluated in Norway.On cold days, thermal comfort in the classroom deteriorated due to cold downdraught from the supply outlet. In addition, moist and fertile conditions for microbiological growth were observed in the air supply ductwork. On the other hand the same pupils are more satisfied with the school and have less sick building syndrome (SBS) symptoms during winter than summer. An improved control strategy with a temperature-compensated CO₂ set-point for controlling the airflow is suggested. This could improve thermal comfort and reduce energy use without compromising perceived air quality (PAQ) during cold weather. Furthermore it could improve indoor air quality (IAQ) during warm weather with only a slight increase of energy use. Further evaluation of an improved solution is needed before such a ventilation concept can be recommended in cold climates.     

严寒地区住宅建筑冬季通风研究

针对严寒地区节能住宅建筑冬季卫生通风不足的问题，本文应用Fluent软件对安装通风装置的示范住宅建筑的室外风场、室内气流组织及温度分布进行模拟研究并实测室内空气温度场。在严寒地区，为保证适当的卫生通风和气流组织，应加强热压的作用，而尽量避免风压的不利影响。对严寒地区典型的建筑住区不同尺度的外部风环境模拟分析结果表明：除建筑住区的迎风面建筑外，整个建筑住区及建筑子区内风场分布较为均匀，符合严寒地区冬季避免冷风侵入耗热量的建筑节能设计。为避免迎风面建筑较高层住宅的背风向房间出现进风口变为排风口的现象，需加强屋顶排风风口处的引风作用；示范性通风建筑室内的进风角度及安装位置、建筑构件、家具的材料以及家具摆放位置等是影响室内热舒适性和室内气流组织的主要原因。     

个性化送风微环境的实验测试研究

通过对人体模型测试和示踪气体测量，研究了一种个性化送风系统中风速、风温和污染物浓度随送风参数的变化状况，并预测了此系统微环境(人员呼吸区)中空气参数的改变程度。结果表明，个性化送风的灵活控制有助于改善局部热环境和空气品质，且呼吸区空气品质的改善程度与送风量、送风距离和人体周围的热羽流均紧密相关。     

Experimental investigation into the interaction between the human body and room airflow and its effect on thermal comfort under stratum ventilation

Room occupants' comfort and health are affected by the airflow. Nevertheless, they themselves also play an important role in indoor air distribution. This study investigated the interaction between the human body and room airflow under stratum ventilation. Simplified thermal manikin was employed to effectively resemble the human body as a flow obstacle and/or free convective heat source. Unheated and heated manikins were designed to fully evaluate the impact of the manikin at various airflow rates. Additionally, subjective human tests were conducted to evaluate thermal comfort for the occupants in two rows. The findings show that the manikin formed a local blockage effect, but the supply airflow could flow over it. With the body heat from the manikin, the air jet penetrated farther compared with that for the unheated manikin. The temperature downstream of the manikin was also higher because of the convective effect. Elevating the supply airflow rate from 7 to 15 air changes per hour varied the downstream airflow pattern dramatically, from an uprising flow induced by body heat to a jet‐dominated flow. Subjective assessments indicated that stratum ventilation provided thermal comfort for the occupants in both rows. Therefore, stratum ventilation could be applied in rooms with occupants in multiple rows.     

Dynamic evaluation of airflow rates for a variable air volume system serving an open-plan office

In a typical air-conditioned office, the thermal comfort and indoor air quality are sustained by delivering the amount of supply air with the correct proportion of outdoor air to the breathing zone. However, in a real office, it is not easy to measure these airflow rates supplied to space, especially when the space is served by a variable air volume (VAV) system. The most accurate method depends on what is being measured, the details of the building and types of ventilation system. The constant concentration tracer gas method as a means to determine ventilation system performance, however, this method becomes more complicated when the air, including the tracer gas is allowed to recirculate. An accurate measurement requires significant resource support in terms of instrumentation set up and also professional interpretation. This method deters regular monitoring of the performance of an airside systems by building managers, and hence the indoor environmental quality, in terms of thermal comfort and indoor air quality, may never be satisfactory. This paper proposes a space zone model for the calculation of all the airflow parameters based on tracer gas measurements, including flow rates of outdoor air, VAV supply, return space, return and exfiltration. Sulphur hexafluoride (SF6) and carbon dioxide (CO2) are used as tracer gases. After using both SF6 and CO2, the corresponding results provide a reference to justify the acceptability of using CO2 as the tracer gas. The validity of using CO2 has the significance that metabolic carbon dioxide can be used as a means to evaluate real time airflow rates. This approach provides a practical protocol for building managers to evaluate the performance of airside systems.