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 airconditioning 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.

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.

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 andGeophysical Fluid Dynamics (LASG). The results of the coupled integration show that the cIimate drift hasbeell controlled successfully. Analyses on the responses of ocean circulation to the changes of surface freshwater or salinity forcing show that the ocean spin-up stage under flux condition for salinity is the key to theimplementation of air-sea fresh water flux coupling. This study also demonstrates that theModified-Monthly-Flux-AnomaIy 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.

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 admixture 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.

Air-void parameters measurement of fresh concrete and hardened concrete

Air content, spacing factor and specific surface of fresh concrete and hardened concrete with different air contents, slumps and mineral admixtures (fly ash, slag, fly ash + slag, fly ash + slag + silica fume composite) were studied by the air-void analyzer (AVA) method and the microscopical method. The correlations between the test results obtained from different methods were analyzed. The results show that, there is a close correlation of air content and spacing factor between the fresh concrete and the hardened concrete, but the specific surface correlation is weak. The air content of concrete measured by the AVA method is smaller than that of the pressure method and the microscopical method, because AVA device captures only the air voids with the size smaller than 3 mm. Spacing factor of the fresh concrete measured by the AVA method is greater than that of the hardened concrete measured by the microscopical method, while the specific surface is smaller. When the criterion of 4%-7% air content measured by the pressure method and microscopical method is acceptable for concrete freezing-thawing (F-T) durability in cold weather, the air content measured by the AVA method should be 2.4%-4.6%. For the concrete F-T durability, when the criterion of the spacing factor measured by the microscopical method is 300 μm, the spacing factor measured by the AVA method should be 360 μm.

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.

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。

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。

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。

一种核电厂重要厂用水泵房环境温湿度高处理方法

高温高湿气候时,东南沿海核电厂重要厂用水泵房频发温度高报警或设备凝露问题,影响泵电机运行安全,降低核电厂冷源安全可靠性。因此,在不改变当前通风方式情况下,提出在泵房进风风室增加一种新风混风制冷机组进行空气温湿度处理的方法。机组采用两路新风,将经制冷除湿后的新风与外界新风混合。通过计算确定进风参数。该方法无需冷却所有新风,无需再热段,通过混风升温降低相对湿度,可以彻底解决所有工况下泵房环境温度、湿度超标问题,且兼顾经济性。

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.

鲜食玉米收获机高净度清选智能测产装置研究

为改善国内小区鲜食玉米育种测产机械装备缺乏、小区鲜食玉米种子清选和测产过程完全依靠人工的现状,设计一种小区鲜食玉米种子高净度清选智能测产装置。该装置采用双层网筛、风力清选、智能测产流程完成高净度清选及测产作业,实现种子高净度清选和智能测产的作业要求。以上筛夹角、下筛夹角和螺旋分离装置入口风速为试验因素,以作业时千克籽粒含杂率为试验指标进行正交试验,建立因素与指标的响应面数学模型,并进行试验验证。结果表明:上筛夹角为14.0°,下筛夹角为4.0°,螺旋清选装置入口风速为27.0 m/s时为最佳作业组合,此参数组合下,鲜食玉米籽粒千克籽粒含杂率为1.2%,籽粒残留清理合格率为99.69%,测产平均误差为0.412%,籽粒含水率测量平均误差为3.57%,玉米种子千粒质量测量平均误差为0.276%。为小区鲜食玉米种子的高净度清选以及智能测产提供研究基础。

通信基站热交换节能分析与智能控制策略研究

随着5G技术的快速进展,电信运营商正面临日益严峻的能源消耗问题。为了有效应对这一挑战,利用自然冷源降低空调能耗的技术受到了广泛关注。自然通风系统减少了对传统空调的依赖,展现了显著的节能效果。然而,这种方法也存在一定的挑战。例如可能导致粉尘积累和维护难度增加,进而影响设备的正常运行。为克服这些挑战,本文提出采用热交换系统进行机房冷却。这一方案不仅高效利用外部低温空气,还减少了粉尘和其它环境污染的影响。本文通过构建热交换模型,深入分析了热交换系统的可行性,并进一步探讨相关的控制策略,为后续热交换系统的应用提供一定的指引。

辐射供冷位置对室内热舒适和能耗的影响分析

辐射供冷空调系统是一种舒适、节能的新型空调系统。为了对比地面、顶板、墙面3种辐射供冷末端位置的室内热舒适和能耗情况,以济南市某办公建筑为例,利用仿真软件建立了辐射供冷加独立新风的复合空调系统,对比分析了3种辐射供冷方式的室内热舒适和房间能耗。结果表明:3种辐射供冷模型下,室内的相对湿度都在40%~60%舒适范围内;墙面和顶板辐射供冷的预测平均投票(Predicted Mean Vote, PMV)值在0.25~0.50之间,而预测不满意百分数(Predicted Percentage of Dissatisfied, PPD)值小于10%,PMV-PPD指标达到了Ⅰ级,热舒适性较好;在设计日运行时间内,地面、顶板、墙面辐射供冷的总能耗分别为5.59、6.23、6.16 kW·h,地面辐射供冷的节能性最好。

基于无机水合盐相变材料的相变蓄冷新风机实验研究

新风系统提高了空气质量,但其温度波动增加了空调系统的负担。相变材料能够利用低品位冷源进行蓄冷,控制新风温度波动。本研究将性能优异的无机复合相变材料与新风机耦合以搭建相变新风机,探究了18、20、22℃的冷水工况下相变新风机的蓄冷性能,发现夜间高温冷源能够满足蓄冷要求,利用相变储热的方式转移用电高峰;此外,相变蓄冷模块能够将28℃的新风温度降低2.4~3℃;基于峰谷电价政策,该装置充分利用电价差可节约54.8%的电力成本。

节能环保技术在暖通空调系统的应用研究

针对暖通空调(HVAC)系统高耗能、高污染的问题,从数据分析方面设计了HVAC系统的智慧数据中心。通过传感器获取HVAC终端的数据,利用联邦学习平均算法实现数据分析。采用多路径通信保证数据传输的安全,实现了HVAC系统精准节能运行。设计了地源热泵功能模块和热能回收功能模块。地源热泵功能模块可实现对太阳能和地热能等可再生能源的利用,保证了HVAC系统的环保性。由试验仿真的分析与对比结果可知,该HVAC系统实现了耗电量和排出热量的减少。该HVAC系统可确保节能环保技术的应用效能。