A Review on Effects of Personalized Ventilation Systems on Air Quality and Thermal Comfort in Aircraft Cabin Mini-Environments

This study conducts an evaluation of air quality,dispersion of airborne expiratory pollutants and thermal comfort in aircraft cabin mini-environments using a critical examination of significant studies conducted over the last20 years.The research methods employed in these studies are also explained in detail.Based on the current literature,standard procedures for airplane personal ventilation and air quality investigations are defined for each study approach.Present study gaps are examined,and prospective study subjects for various research approaches are suggested.

Indoor Air Quality and Thermal Comfort Evaluation in Latvian Daycare Centers with Carbon Dioxide, Temperature and Humidity as Indicators

Latvian children under the age of 7 can spend up to 60 hours per week in daycare centers and therefore it is very important to establish a healthy and comfortable daycare environment that children will find pleasant and stimulating to stay in. This study investigates indoor air quality and thermal comfort within six daycare centers （old, renovated and new-built） in moderate climate zone of Latvia. Measurements of carbon dioxide, air temperature and relative humidity were carried out, and data regarding daycare center characteristics and maintenance activities was collected via combination of field visits, record analysis and interviews. It was found that carbon dioxide concentrations exceeded 1000 ppm in 75% of daycare centers studied, with the highest （1356 ppm） measured in a renovated facility with the natural ventilation system. Thus installation of more efficient ventilation system （mechanical） is recommended to provide acceptable indoor air quality, since opening of windows itself cannot provide the optimal conditions indoors. In all facilities the temperature was kept above 20℃ and the average relative humidity was 40±35%, creating comfortable thermal environment for children.

Field study of thermal comfort and indoor air quality in gymnasium

To analyze the thermal comfort and indoor air quality (IAQ) in a medium-sized mechanically ventilated gymnasium in Beijing,a field study was carried out. PHOENICS,one of the CFD software,was chosen to simulate the distribution of the indicators of indoor air in the gymnasium to check the air-conditioning parameters reasonable or not. And there was a questionnaire for audiences and staff about the acceptance and satisfaction of the thermal comfort,simultaneously,some environmental parameters were monitored. Then an experiment was carried out in gymnasium with the plate sedimentation to the biological aerosol in the air. Finally,the thermal comfort and IAQ in the gymnasium were assessed based on the results of above questionnaire survey and measurements. The results show that most parameters of the environmental are within the standard limits of thermal comfort and IAQ in the monitored period,and the biological contaminants initially come from human beings. The main species in the gymnasium are streptobacillus,coccus,cladosporium,penicillium and neurospora.

Efficacy of coupling heat recovery ventilation and fan coil systems in improving the indoor air quality and thermal comfort condition

Mechanical Ventilation with Heat Recovery(MVHR)systems are gaining increasing interest in buildings with low energy demand,for improvement of the Indoor Air Quality(IAQ)and reduction of the ventilation energy loss.In retrofitted buildings,MVHRs are often integrated with an additional air heater to cover space heating demand.Hence,evaluation of the interactions between MVHR and heat emitter,and their effects on indoor airflow characteristics is of significant importance.The present study aims to investigate effects of a combined MVHR-fan-coil system in heating mode on IAQ and thermal comfort parameters inside a retrofitted room,by means of a computational fluid dynamic(CFD)code.The proposed CFD model is validated by comparing the numerical results with experimental data.The results yielded by numerical simulations allow evaluating the indoor environmental quality characteristics as well as addressing the MVHR and fan coil interactions.The results indicate that the airflow discharged from the fan coil could have a significant impact on the age of the air;while it provides a desirable thermal comfort condition within the room,it may hinder to some extent delivery of the fresh air to the occupied zone due to creation of counterflow fields.Furthermore,it is shown that although increasing the fan speed(ON mode)would slightly enhance the air change efficiency,the OFF mode yields not only a better distribution of the fresh air but also a higher ventilation efficiency than when fan coil operates.

Prediction of Perceived Air Quality for Personalized Ventilation Systems

The characteristics of the air jet from the outlet of a personalized ventilation system were related to the perceived air quality and ventilation rate. The perceived air quality was expressed as percentage of dissatisfied people for a system supplying isothermal fresh air. The relationship was verified using a thermal manikin with a breathing function in a climate chamber sitting by a desk equipped with a personalized venti- lation system. A trace gas was introduced into the climate chamber and fully mixed. The personal exposure effectiveness (εp) is based on concentrations of trace gas in the chamber and in the manikin nose which is affected more by the distance between the movable outlet and the occupant’s breathing zone than by the personalized air flowrate and does not change much for the personalized air flowrate higher than 10 L/s when the distance is fixed. Some predicted dissatisfied values for a personalized ventilation system com- pared with those acquired in human subject experiments have an absolute difference of less than 3%.

Experimental study on indoor environment improvement in toll booth by personalized ventilation technology

The necessity and feasibility of the use of the personalized ventilation（PV）technology in a toll booth is described.First,the indoor environment of the toll booth equipped with a PV system is analyzed.Based on the analysis results,a set of equipment for controlling the indoor air quality（IAQ）of the toll booth is devised.Then,a full-scale model of the toll booth is set up in the laboratory.The airflow organization,the optimum operation parameters,and the restraint effects of the PV system on pollution are also experimentally studied.The experimental results on the air supply characteristics show that the PV system can effectively reduce the air age,improve the ventilation efficiency,and enhance the comfort and acceptability of human beings.In addition,this system plays a significant role in preventing pollution.

Model-based adaptive controller for personalized ventilation and thermal comfort in naturally ventilated spaces

This work develops a standalone autonomously controlled personalized ventilation(PV)unit in a naturally ventilated(NV)office space to maintain acceptable thermal comfort{TQ under steady and transient indoor conditions and activity levels.The NV-PV proportional integral derivative(PID)controller adjusts the PV supply temperature(7spv)at the occupant set flow rate(Qspv)based on predicted TC using a regression model.The target TC level that the controller attains at all times is between 0(neutral)and 1(slightly comfortable).Process transfer functions were developed and then used to find the adaptive PID tuning coefficients using the Internal Model Control(IMC)method.The controller was tested in a case study at indoor temperature range of 25 to 33℃ with relative humidity range of 55%and 80%.It was shown that the NV-PV controller adjusted Tspv to maintain acceptable TC under transients of indoor conditions and metabolic rates.

Evaluation of thermal comfort and air quality of low-income housing in Kampala City,Uganda

This paper presents the results of thermal comfort and air quality studies in naturally ventilated residential buildings in Kampala City,Uganda.Questionnaire surveys were used for obtaining occupant subjective thermal sensation votes.Indoor and outdoor measurements for air temperature(T_(a)),Mean Radiant Temperature(MRT),relative humidity,air speed,and air quality were done for seven buildings over fifteen days during the month of June 2019.DesignBuilder software was used to develop the reference building model and to simulate strategies for improvement of thermal comfort.Survey results showed that 67.8%of the respondents were comfortable with the indoor thermal environment.The indoor air temperature range was 22.7℃-27.9℃ which lies within the 80%acceptable limits set by ASHRAE 55.The measured indoor MRT range was 24.24℃-25.57℃.Measured levels of indoor PM_(2.5)were double the World Health Organization recommended limits,while the levels of PM 10 were thrice the recommended limits of ASHRAE 62.1.The CO_(2)concentrations were within the limits set by ASHRAE 62.1.The developed model predicted comfortable indoor conditions with a temperature range of 23.6℃-25.3℃ based on the 80%acceptable limits set by ASHRAE 55.The results show that majority of occupants preferred cooler temperatures during the day which is justified by the use of adaptive measures to obtain thermal comfort.

Impact of indoor heat load and natural ventilation on thermal comfort of radiant cooling system:An experimental study

Construction and operation of buildings are responsible for about 20%of the global energy consumption.The embodied energy of conventional buildings is high due to the utilization of energy-intensive construction mate-rials and traditional construction methodology.Higher operational energy is attributed to the usage of power-consuming conventional air-conditioning systems.Therefore,moving to an energy-efficient cooling technology and eco-friendly building material can lead to significant energy savings and CO 2 emission reduction.In the present study,an energy-efficient thermally activated building system(TABS)is integrated with glass fiber rein-forced gypsum(GFRG),an eco-friendly building material.The proposed hybrid system is termed the thermally activated glass fiber reinforced gypsum(TAGFRG)system.This system is not only energy-efficient and eco-friendly but also provides better thermal comfort.An experimental room with a TAGFRG roof is constructed on the premises of the Indian Institute of Technology Madras(IITM),Chennai,located in a tropical wet and dry climate zone.The influence of indoor sensible heat load and the impact of natural ventilation on the thermal comfort of the TAGFRG system are investigated.An increase in internal heat load from 400 to 700 W deteriorates the thermal comfort of the indoor space.This is evident from the increases in operative temperatures from 29.8 to 31.5℃ and the predicted percentage of dissatisfaction from 44.5%to 80.9%.Natural ventilation increases the diurnal fluctuation of indoor air temperature by 1.6 and 1.9℃ for with and without cooling cases,respectively.It reduces the maximum indoor CO 2 concentration from 912 to 393 ppm.

Comparison study of thermal comfort and energy saving under eight different ventilation modes for space heating

The relative location of inlets and outlets plays an important role in thermal comfort and energy conservation under ventilation modes for the building non-uniform indoor environment.Hence,a comparison study of thermal comfort and energy efficiency of eight widely-used ventilation modes for space heating was conducted in this study.Both subjective experiments and verified computational fluid dynamics(CFD)models were carried out.In the subjective experiments,the vote of local thermal sensation(LTS),overall thermal sensation(OTS)and draft sensation were collected.In the CFD simulations,RNG κ-ε model was applied to compare and analyze the air temperature field,turbulence intensity,ventilation effectiveness and air diffusion performance index(ADPI).The thermal comfort results showed that the air inlets are better located at the mid-height level of a wall,and the outlets are located at the same or higher height.While the results of the energy efficiency suggested that the inlets are better installed at the lower level of a wall,and the outlets should be placed far from the inlets.Since the results were conflict,the economic-comfort ratio was introduced to calculate and compare the thermal comfort and energy efficiency simultaneously.The final results concluded that it can achieve excellent thermal comfort performance without sacrificing energy efficiency when the inlets are at the height of 1.2 m of the front wall,and the outlets are at 1.2 m height of the back wall.Hence it is the best choice for the winter air distribution in northern China.This study can offer a guideline for the air terminal arrangements in non-uniform ventilation under heating mode.

Adaptive thermal comfort in naturally ventilated hostels of warm and humid climatic region,Tiruchirappalli,India

Thermal comfort is an important factor in hostel buildings when the aim is to maximize the productivity of the students.Due to the extreme weather conditions,achieving thermal comfort in a hostel building in a hot and humid climate is even more difficult.Studies conducted in naturally ventilated hostel buildings in warm-humid climates involved the influence of outdoor air temperature only up to 34.4℃ and have been conducted in a specific season.In contrast,the Tiruchirappalli climate is characterized by a higher range of environmental variables.Therefore,to understand the thermal comfort conditions and usage of the environmental controls in naturally ventilated hostel buildings at the higher range of the environmental variables,a thermal comfort field study spread over one year was carried out at the National Institute of Technology,Tiruchirappalli,India,in twenty-seven hostel buildings.This study relies on field observation and thermal comfort responses from 2028 questionnaires collected from the students between September 2019 to August 2020.The analysis revealed a neutral temperature of 29.5℃ and a comfort range from 26.1℃ to 32.8℃,indicating a wide range of ther-mal adaptation than suggested by the National Building Code of India and ASHRAE standard 55.The preferred temperature was 27.8℃,indicating that students preferred a cooler environment.Acceptability with sweating conditions extended the upper limit of thermal acceptability from 31.8℃ to 32.4℃.The use of a mosquito net can increase the probability of opening a window.Results indicated that overall behavioral adjustment could extend the comfort limits.The study results would be helpful to develop guidelines and designs for naturally ventilated hostel buildings in warm and humid climates that will contribute to reducing energy demand.

Indoor Environmental Quality of Air Conditioned Residential Buildings in Extreme Dry Desert Climate

In this study, the indoor environmental quality (IEQ) in air conditioned residential buildings in a dry desert climate is examined from the perspective of occupants via two aspects: thermal comfort and indoor air quality. The study presents statistical data about the domestic-occupant thermal comfort sensations together with data describing the indoor air quality in Kuwaiti residential buildings. With respect to the latter, the overall IEQ acceptance using two measurements namely: physical measurements and subjective information collected via questionnaires, was used to evaluate 111 occupants living in twenty five air-conditioned residential buildings in the state of Kuwait. The operative temperature based on Actual Mean Vote (AMV) and Predicted Mean Vote (PMV) was identified using linear regression analysis of responses on the ASHRAE seven-point thermal sensation scale and was found to be 25.2°C and 23.3°C, respectively, in the summer season. Indoor air quality (IAQ) with respect to carbon dioxide concentration level was compared with the acceptable limits of international standards, i.e. ASHRAE Standard 62.1 [1]. The proposed overall IEQ acceptance findings in residential buildings show CO2 concentration level between 909 and 1250 ppm. However, this may be considered a higher level of CO2 concentration, which may require increasing ventilation rate through window operation or mechanical ventilation.

Energy performance assessment on central air-conditioning system of commercial building: A case study in China

Energy performance assessment on central air-conditioning system is essential to optimize operating, reduce operating costs, improve indoor environmental quality, and determine whether the retrofitting of the equipment is necessary. But it is difficult to evaluate it reasonably and comprehensively due to its complexity. A "holistic" approach was discussed to evaluate the energy performance of central air-conditioning system for an extra-large commercial building in a subtropical city. All procedures were described in detail, including field investigation method, field measurement instruments, data processing and data analyzing. The main factors affecting energy consumption of air-conditioning system were analyzed and the annual cooling-energy use intensity of this building was calculated and also compared with other shopping malls and other types of buildings in Guangzhou. And COP(coefficient of performance) of chiller, water transfer factor of chilled water system and cooling water system were taken into consideration. At last, the thermal comfort and indoor air quality issues were addressed. The results show that the chilled water pumps are over-sized and the indoor environmental quality should be improved. The purpose of this work is to provide reference for energy performance assessment method for air-conditioning system.

Numerical Investigation of Different Airflow Schemes in a Real Operating Theatre

A study on performances of different ventilation schemes provided by vertical and horizontal uni-directional air flow was carried out in a standard orthopaedic operating theatre (OT). Starting from our previous studies of a real OT under operating use conditions, in this research different air flow configurations, considering some air curtain solutions on the ceiling and at the sliding door always assumed to be open as a basic boundary condition, were investigated by numerical simulations. Indoor air quality (IAQ) indexes and thermal comfort parameters, deduced from simulation results were calculated and discussed referring to the best performance and efficacy between the air flow schemes to contrast the incorrect use conditions of the OT. Referring to the studied schemes, the reciprocal comparison emphasizes that a successful outcome in preventing surgical site infection can depend as much on resolving human factors (i.e. operational use conditions, door opening/closing), as on overcoming physical and technical obstacles.

严寒地区混合垂直通风猪舍环境质量评价

为探究垂直通风系统(屋顶与粪坑混合排风)在寒区猪舍中的适应性,该研究在秋冬季节对内蒙古某规模化猪舍的热湿与空气质量环境进行了实时连续监测,并根据测试结果对猪舍环境质量进行评价。结果表明:1)测试期间,舍内平均温度、相对湿度以及氨气(NH_(3))、二氧化碳(CO_(2))、总悬浮颗粒物(total suspended particulate, TSP)浓度分别为22.7℃、59.6%、6.5 mg/m^(3)、2 200 mg/m^(3)、2 915μg/m^(3),舍内通风量为0.34~0.39 m^(3)/(h·kg),各环境指标基本满足生产环境阈值要求;保育期间舍内有效环境温度范围为27.1~30.7℃,存在轻度热应激情况,占总监测时间的12.9%;2)舍内温度、相对湿度与NH_(3)、CO_(2)、TSP浓度空间分布不均匀系数分别为0.01、0.15、0.45、0.03、0.15,各环境参数空间分布均较为均匀;3)试验单元(U1、U3)猪的平均日增质量、料重比与死淘率分别842和818 g/d、2.68和2.79、1.68%和1.31%,生产性能良好。综上,不设吊顶的侧墙进风,屋顶与粪坑混合排风的垂直通风系统,总体上能够满足严寒地区猪舍秋冬季热湿环境与空气质量调节需求,保证良好的生产性能。

洁净手术室气流组织效果的影响因素综述

我国医院建设规模庞大、分布广泛,就医人数居世界第一,医疗洁净手术室空气洁净技术发展迅速。手术室的气流组织是其空气洁净技术的重要方面,与手术部位感染的关系一直存在争议。本文对手术室中的气流组织形式进行了综述。研究表明,层流通风和温控气流通风在去除携带细菌的颗粒方面具有优势,且层流通风对飞沫的控制能力更强。本文梳理了手术室内人员数量和位置、手术人员的动作和流动、医用设备的数量和发热量、人员着装和手术台次等因素对气流组织效果的影响。发现手术人员的动作和流动是相关研究的热点,气流组织与手术人员、患者热舒适的关联仍有待深入。未来研究方向包括手术室内局部气流组织与手术微环境空气质量的定量关系、新型气流组织形式和末端、个性化通风与手术人员热舒适等。

基于室内非均匀环境营造的新型通风模式下人员热舒适性及系统节能潜力

为解决现有通风空调系统无法根据占用区域实现按需供冷造成的热不舒适及能源浪费问题,本研究根据人员占用区域需求实时切换气流模式组合及冷量供给,提出了一种新型通风模式,旨在利用多种气流模式的最优组合控制特定需求场景。采用数值模拟的方法探究了不同占用区域情况下新型通风模式的人员热舒适性和系统的节能潜力,并与混合通风模式和层式通风模式进行了对比。结果表明:新型通风模式在气流组织上具有明显优势;新型通风模式较混合通风模式和层式通风模式具有更高的热舒适性,空气分布特性指数最大;新型通风模式局部冷量利用系数最小,冷量有效利用率最高,所需供冷量最小,因此新型通风模式的节能潜力最大。

集中供暖建筑不同计费模式对空气品质满意度的影响研究

为了探究寒冷地区不同供暖计费方式下空气品质满意度对热舒适度的影响,对中国河南省焦作地区某居民住宅分别于2018年、2020年两个供暖季进行了现场研究。在测量环境参数时,也采集了受试者的热舒适状况。通过对比、分析发现,在不同热计量方式下,用户的热感觉、空气品质满意度及行为调节均存在统计学上的显著差异。相较于按面积收费,按流量收费住户的热反应与空气品质满意度都更好。本研究旨在揭示空气品质满意度与热感觉、调控行为的关系,并为供暖计费方式的选择提供参考。

南昌高校宿舍夏季睡眠环境现场调查与统计分析

以南昌某高校学生宿舍为研究对象,测量了夏季夜间室内温度、相对湿度、风速、CO_(2)浓度等环境参数,并对26名受试者睡前和醒后的主观环境评价及睡眠质量进行了调查。利用统计学方法对测量和调查结果进行了分析,结果表明:睡眠状态与睡前清醒状态热中性温度都为25℃,睡眠状态有比清醒状态更宽的可接受温度范围;宿舍夜间CO_(2)浓度较高,醒后室内空气品质满意度比睡前显著降低,应适当增强通风;睡眠期间较高的室内温度、相对湿度和CO_(2)浓度都会导致睡眠质量下降;夜间凉爽且通风良好的室内环境更有利于提高学生睡眠质量。

汽车乘员舱个性化热舒适智能空调决策系统设计

为了进一步提高汽车乘员舱空调系统的智能化和舒适性水平,本文提出了一种基于热舒适理论的个性化智能空调决策系统设计方案。首先,针对汽车乘员舱改进了基于PMV(predicted mean vote)和PPD(predicted percentage of dissatisfaction)理论的热舒适性计算方法;进一步,利用人体画像技术实现了乘员舱驾乘人员的热舒适性特征提取,并在专家经验知识的基础上构建了具有理论计算依据的乘员舱热舒适数据集;然后,利用机器学习算法搭建了个性化热舒适空调系统随机森林决策模型,以此满足个性化热舒适智能决策需求;最后,给出了完整的系统框架和设计。测试结果显示所提出的系统模型决策准确率在90%以上,实车测试结果表明:本文系统能够识别驾乘人员特征,实时进行个性化热舒适性参数推荐,验证了本研究决策方法的有效性和实用价值。