Analysis of Fresh Air Volume of Air-conditioning System for Railway Vehicles

The relevant standard requirements both in domestic and abroad provide the basis for designing air-conditioning system of railway vehicles present. However, there are great differences in the fresh air volume indicators among different standards requirements, and the requirements of each vehicle procurement contracts are also different. The design of air-conditioning become difficult above these. In this paper, the fresh air volume of different type railway vehicles is analyzed from health and equipment electricity consumption according to the railway vehicles air-conditioning system standard requirements in domestic and abroad. Some advises for designing air-conditioning system of railway vehicles through the fresh air volume calculation and comparison for domestic air-conditioning system of railway vehicles was provided.

Research on the Phase Change Solar Energy Fresh Air Thermal Storage System

In this article, a new kind of solar fresh air system is designed in order to realize the improvement of thermal efficiency by the integrated application of the PCMs and heat pipe technology. Under the adequate sunshine condition, the fresh air is directly delivered into the indoor environment after being heated by the solar collector. When the sun radiation is reduced, the heated air temperature can not satisfy the need of supply of air temperature.The main heat source is changed to phase change heat storage equipment instead of solar energy. The system adopt heat pipe for a high-efficiency and isothermal heat transfer which recover the shortcomings of PCMs such as： low coefficient of thermal conductivity and poor thermal efficiency. This article establishes the physical model of phase change solar energy fresh air thermal storage system and creates the mathematical model of its unsteady heat transfer to simulate and analyse the operation process by using Fluent software. The results of the study show that, compared to normal fresh air system, the phase change solar energy fresh air thermal storage system has a significant improvement in energy saving and indoor comfort level and will play an important role in the energy sustainable development.

How to Get A Breath of Fresh Air

Heavy smog shrouded China＇s central and eastern regions for days this past January, and experts are advising citizens to stay inside. But how much safer is our indoor air？ The U.S. Environmental Protection Agency＇s research shows that 24 million people in the world die every year as a result of poor indoor air quality, said Song Guangsheng, Secretary General of China＇s Indoor Environment Test Center （CIETC）.

Air purifier or fresh air system?A comparison of energy consumption and cost in urban China residential buildings

Chinese urban residential buildings face serious indoor air quality problems.Air purification systems(e.g.,air purifiers,fresh air systems)that supply fresh air or purify indoor air are widely used in residential buildings to improve indoor air quality.Considering the challenges of energy conservation and emission reduction,it is urgent to guide residents on choosing appropriate air purification systems.The key problem is how to identify the best air purification system with the lowest energy consumption or operating cost.Comparisons of air purification systems have rarely been conducted on the premise that they should deliver air such that the main indoor pollutant concentrations all meet air quality standards.Also ignored in comparisons are the increased filtration resistance caused by dust accumulation on the filter and the cost of filter replacement.In this study,we propose a method to compare residential air purification systems based on energy consumption and total cost,and we provide methods to select air purification systems in China's different climatic regions.We used a standard two-person bedroom as the example,and determined the most suitable(minimum cost or energy consumption)air purification systems for the capital cities of the provinces in Chinese mainland.

Solid Desiccant Heat Pump Fresh Air Unit using Composite Silica Gel

The introduction of fresh air into the indoor space leads to a significant increase in cooling or heating loads.Solid desiccant heat pump fresh air unit which can handle the latent and sensible load of fresh air efficiently have been proposed recently.To improve the performance of the solid desiccant heat pump fresh air unit in the fresh air handling process,in this paper,the application of composite silica gel in a heat pump fresh air unit was investigated.The comparison between silica gel coating(SGC)and composite silica gel coating(CSGC)shows that the adsorption rate and water uptake capacity of CSGC are more than two times higher than those of SGC.An experimental setup for the solid desiccant heat pump fresh air unit was established.The performance of SGC and CSGC was tested in the setup successively.Results show that under summer conditions,compared with the solid desiccant heat pump fresh air unit using silica gel(SGFU),the average moisture removal and COP of the one using composite silica gel(CSGFU)increased by 15%and 30%,respectively.Under winter conditions,compared with SGFU,the average humidification and COP of CSGFU increased by 42%and 17%.With optimal operation conditions of 3 min switchover time and 40 r/s compressor frequency,the COP of CSGFU under summer conditions can reach 7.6.Results also show that the CSGFU and SGFU have higher COP and dehumidification rate under higher outdoor temperature and humidity ratio.

Electrochromism-induced adaptive fresh air pre-handling system for building energy saving

Building fresh air supply needs to meet certain regulations and fit people’s ever-growing indoor air quality de-mand.However,fresh air handling requires huge energy consumption that goes against the goal of net-zero energy buildings.Thus,in this work,an adaptive fresh air pre-handling system is designed to reduce the cool-ing and heating loads of HVAC system.The sky-facing surface of the system uses electrochromic mechanism to manipulate the optical properties and thus make full use of solar energy(solar heating)and deep space cold source(radiative cooling)by switching between heating and cooling modes.In the cooling mode,the sky-facing surface shows a transmittance of down to zero,while the reflectance is high at 0.89 on average.In the heating mode,the electrochromic glass is highly transparent,allowing the sunlight to reach the solar heat absorber.To obtain the energy-saving potential under different climates,six cities were selected from various climate regions in China.Results show that the adaptive fresh air pre-handling system can be effective in up to 55.4%time of a year.The maximum energy-saving ratios for medium office,warehouse,and single-family house can reach up to 11.52%,26.62%,and 18.29%,respectively.In addition,the system shows multi-climate adaptability and broad application scenarios,making it a potential solution to building energy saving.

基于Airpak的幼儿园生活单元空气质量模拟分析

通过对幼儿园生活单元建立物理数学模型,基于Airpak模拟分析了排风量、新风量、新风口位置以及室外风速对室内空气品质的影响。结果表明,门窗关闭的室内,仅设置排风并不能有效降低室内CO_(2)平均浓度;引入新风对降低室内CO_(2)平均浓度效果显著;新风口距离人员越近,并非越有利于降低室内CO_(2)平均浓度;过渡季节,开启门窗室内CO_(2)平均浓度水平明显降低。

Energy saving potential of a fresh air pre-cooling system using radiative sky cooling

To achieve required indoor air quality,fresh air supply in buildings should meet relevant standards and regulations.However,the handling of fresh air introduced a cooling load that takes up a large portion of building energy consumption,especially in tropical and subtropical areas.A proper way should be employed to reduce the cooling load of fresh air.Radiative sky cooling,which is the process that an object cools itself by emitting thermal radiation to outer space without any energy input,is a cost-effective and eco-friendly technology.In this work,a fresh air pre-cooling system using radiative sky cooling is proposed to reduce fresh air cooling load.The system,consisting of filters,a radiative air-cooling system,an air handling unit(AHU),fans,etc.,is installed on the rooftop of the modeled building.Six cities in low-latitude areas are selected and investigated.Results show that with the radiative air-cooling system installed,annual cooling energy consumption of the modeled building can be reduced by around 10%in most cities.For arid areas,e.g.,Abu Dhabi,the system has even better performance with 19.34%annual cooling energy saving.

Response of IAP/LASG GOALS Model to the Coupling of Air-Sea Fresh Water Exchange

The process of air—sea fresh water exchange is included successfully in the Global— Ocean—Atmosphere Land—System model developed at the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (LASG). The results of the coupled integration show that the climate drift has been controlled successfully. Analyses on the responses of ocean circulation to the changes of surface fresh water or salinity forcing show that the ocean spin-up stage under flux condition for salinity is the key to the implementation of air-sea fresh water flux coupling. This study also demonstrates that the Modified—Monthly—Flux—Anomaly coupling scheme (MMFA) brought forward by Yu and Zhang (1998) is suitable not only for daily air—sea heat flux coupling but also for daily fresh water flux coupling. Key words Fresh water flux - Air-sea coupling - Thermohaline circulation This work was co-supported by the National Key Project (Grant No.96-908-02-03), the Excellent National Key Laboratory Research Project (Grant No.49823002) and Chinese Academy of Sciences (CAS) under grant “ Bai Ren Ji Hua? for “Validation of Coupled Climate Models”.

An algorithm for calculating fresh air age in central ventilation system

Fresh air age is an important index to evaluate indoor environment. The conventional method for measuring or calculating fresh air age is only suitable for simple ventilation systems and not for central ven-tilation systems. In this paper, an algorithm for calculating fresh air age in central ventilation system is pre-sented, which is based on the analysis of air flow in duct and air mixing. An example is given to illustrate the algorithm. The fresh air age in every ventilated room and duct can be acquired after all rooms and duct are directly calculated in turn without iteration. The algorithm is suitable for different central ventilation sys-tems.

Air-void Parameters Measurement of Fresh Concrete

To explore the method to evaluate air-void parameters of fresh concrete rapidly, the spacing factor and specific surface of freshly mixed concrete of different air contents, different slumps and different mineral admixtures （fly ash, fly ash-slag, fly ash-slag-silica fume composite） are studied by air-void analyzer （AVA）, and the correlation between the air content measured by AVA and air content determinator is compared. The results show that the spacing factor of the fresh concrete decreases firstly and then increases with the increase of air content, however the specific surface has the opposite rule. When the air content is more than 8%, the spacing factor of fresh concrete increases and the specific surface decreases. For the fresh concrete samples with similar air content, the specific surface increases firstly and then decreases with the increase of slump, but the spacing factor decreases firstly and then increases. Mineral admixalre can reduce the spacing factor of fresh concrete and increase the specific surface to some degree. There is a good correlation between the air content measured by two methods, and the air content measured by AVA is about 70% of the air content measured by the air content determinator.

Heat transfer performance of fresh-air handing device using earth energy

In order to reduce the fresh-air handing energy consumption,a fresh-air handing device using earth energy was presented. The major part is a double pipe soil-air heat exchanger. Its performance was tested in summer and winter. The results show that while the volume of the treated fresh-air is 125 m3/h,in summer,at the outlet of the device,the air temperature is 21.5-24.0 ℃,the air humidity ratio is about 17 g/kg,the greatest temperature drop is about 9 ℃ ,and the largest dehydration quantity is about 6 g/kg. In winter,at the outlet of the device,the air temperature is 15-17 ℃,the air humidity ratio is about 11 g/kg,the largest temperature rise is about 11 ℃,and the largest humidification quantity is about 6 g/kg. Therefore,the application of this new fresh-air handing device can take full advantage of the natural energy,thus effectively reduce the traditional energy consumption for fresh-air handing.

一种新型溶液除湿空调系统能耗及应用分析

传统空调系统通常采用温湿度联合处理的方式,该方式存在舒适性差、能源消耗大等问题。针对以上问题,提出一种利用复合直接蒸发冷却制冷水的溶液除湿空调系统,该系统可以有效节省功耗,符合节能减排的发展趋势。在研究过程中,以某办公楼为研究对象,利用TRNSYS仿真软件建立该系统,研究其在制冷季7—9月的能耗,分析其节能性及适用性。结果表明:当空调新风系统使用太阳能热水作为再生热源时,总供热能耗为6.1×10^(5)kW·h,总耗功为8.73×10^(4)kW·h。相比于传统空调系统,节能率达到55.2%,为降低空调系统能耗提供了新思路。

严寒地区超低能耗教学建筑新风系统适用性分析

目的 解决严寒地区超低能耗建筑中人员密集场所供暖期新风系统的适用性问题。方法 以沈阳市某小学教学楼中三种典型教室为例,应用Designbuilder软件建立能耗模型,分析自然通风、有无热回收的定(变)风量机械通风五种工况下超低能耗建筑的各项能耗、相对节能率和本体节能率,以及室内CO_(2)体积分数变化。结果 无热回收的变风量、有热回收的定(变)风量与无热回收的定风量机械通风相比,节能率分别为12%~30%、32%~46%、38%~57%;有热回收的变风量机械通风总能耗最低,且接近自然通风工况;五种工况室内CO_(2)体积分数均小于0.09%。结论 人员密集场所中有热回收的定(变)风量机械通风节能效果显著;建筑气密性的提高导致机械通风系统新风能耗增加,经济性和节能性下降。

风机盘管加新风系统室内微循环热舒适性研究

随着人们生活水平的提高,医院在提升治疗服务的同时迫切需要改善患者就医环境和医护人员的工作环境。目前,医院建筑中特别是病房广泛应用的风机盘管加新风系统存在温度分布不均匀、吹风感较强、噪音大等问题,导致了患者的室内热舒适性无法得到保障。因此,针对医院病房,探索研究风机盘管加除湿置换新风空调系统,在实际搭建的实验平台基础上建立CFD数值模拟模型,将模拟结果与实验数据相对比,论证了模型的准确性之后,通过CFD模拟的方式,在保证对流换热可以达到室内设定温度的前提下,找到一种新的气流组织形式,这样不仅有效降低室内人员的吹风感和噪音,而且避免了传统置换通风容易出现温度分层、垂直温差过大的问题。

室内空气调节系统的研究与设计

车间环境中,生产活动可导致空气质量恶化,极大影响员工身体健康。文章提出了一种空气调节系统,用于监测室内空气粉尘和VOC污染物浓度,适时开启换气系统,使空气参数保持在较高的水平。该系统集成多组粉尘和VOC检测模块和双向换气装置,根据发生空气质量恶化区域自适应调整空气流动路径,有针对性的净化空气。车间外设置风向传感器,根据自然风的风向调整室内换气方向,提高换气效率。各个监测点和执行点利用WiFi实现自组网,点与点之间密切配合,提高系统换气效率。验证试验表明:监测器能够稳定运行,点与点之间配合良好,高效率、针对性实现空气净化,大大改善了车间生产环境。

空调及换气系统运行对室内PM_(2.5)净化效果的影响

为了研究室内空调与换气系统运行时空气净化器对室内空气的净化效果,采用试验研究和CFD模拟相结合的方法,研究了空调与换气系统运行对净化器将室内PM_(2.5)净化到ASHRAE规定的可接受室内空气质量的限值15μg/m^(3)的净化时间的影响。结果表明,净化器外加空调净化时间相比净化器单独运行时间缩短15.2%;净化器外加换气系统净化时间相比净化器单独运行时缩短了30.4%;三系统联合运行时的净化时间相比净化器单独运行时间缩短32.6%。结果可为研究空调与换气系统对空气净化器净化效果的贡献及室内空气净化方式提供参考。

基于智能新风系统的旧实验楼宇改造的探索

以同济大学化学馆整体改造建设项目为例,介绍了基于智能新风排风联动系统的化学馆楼宇整体改造的各项措施,包含在设计中融入EHS体系、依据通风要求分等级分区设计、各项节能措施以及长效运行机制等。在项目改造过程中,以EHS理念为指导,以节能长效为目标,完成了旧楼改造的既定目标,师生满意度达到99%。本案例作为化学类老旧实验楼宇改造领域的有益探索,为旧实验楼改造和提升提供了一个典型范例,为后续工作积累了经验。

基准排放因子更新对隧道需风量的影响研究

为解决交通车辆持续更新导致的城市隧道内通风系统设计浪费和运营闲置,研究基准排放因子更新对隧道需风量的影响,并建立2种应对车辆更新的基准排放因子计算方法.首先,通过理论分析明确需风量计算式中随时间更新的关键参数为基准排放因子;随后,根据定量分析得到基准排放因子和纵坡-车速系数更新对需风量的影响;最后,结合国外理念和实际设计经验,提出2种考虑时间更新的基准排放因子计算方法.研究结果表明:我国道路隧道通风设计规范在制定基准排放因子时参考了世界道路协会(PIARC)通风报告,并分析得到了参考理由;与2000年相比,2021年的CO、NOx和PM基准排放限值分别降低了81.6%、76.7%和97.9%;建立了使用机动车污染物排放限值作为基准排放因子的最不利设计方法,计算出2018年各污染物基准排放因子(CO为0.0011 m^(3)/(辆·km),PM为0.4610 m^(2)/(辆·km)),相比于2014年《细则》分别降低84.3%和77.0%.建立并验证了基准排放因子计算方法,为城市道路隧道通风系统设计提供参考.