bluuebunny/crossref_metadata_2025 huggingface dataset:
Analyzing the energy-saving effect of the low-level wall-exhaust ventilation system in restroom
Authors: Jia Yonghong , Wang Nan , Du Kang , Li Angui
Published: August 2022

For responding the policy call of building a green and low-carbon society and meeting the goal of economizing energy and reducing emission in the process of construct. The troditional ceiling-exhaust ventilation system in restroom should be replaced by the new low-level wall-exhaust ventilation system for better exhaust effect and less air changes per hour which help in solving the existing problems, such as excessive design value of air changes per hour, serious heating/cooling loss and so on.
Analysis on night ventilation effect of buildings with different energy consumption levels in Shenyang
Authors: Xiaoxu Li , Kailiang Huang , Guohui Feng , Danyang Jing , Dan Liu , Jiawei Li
Published: August 2022

In this paper, the effects of night natural ventilation on indoor thermal environment of ultra-low energy consumption in a university in Shenyang were evaluated. The DeST software was used to establish the ultra-low energy consumption building model and the conventional building model, and the accuracy of the model is also verified experimentally. The indoor temperature, building power consumption of air conditioning system of the two models were calculated under the natural ventilation condition at night. The results show that under the optimal night natural ventilation conditions in July and August, the energy saving rate of ultra-low energy building refrigeration system is 15% and 46% respectively. The energy saving rate of conventional building refrigeration system is 14% and 44% respectively. The peak indoor temperature of the two types of buildings decreases with the increase of natural ventilation time at night. Both ultra-low energy consumption buildings and conventional energy consumption buildings adopt natural ventilation at night to help reduce indoor temperature, building power consumption of cooling system.
Automatic Compliance Check of Window-to-Wall Ratio Software Embeded Intelligent Algorithms in Revit Modeling
Authors: Yan Xiu-ying , Wang Xiu-dong , Li Da-wei , Yan Xiulian , Fan Kai-xing , Liu Da-long
Published: August 2022

Window-to-Wall Ratio(WWR) is a crucial building envelope element that decides the air conditioning and lighting energy consumption in the building. Controlling WWR within a reasonable range is of great significance to building energy conservation. Due to the importance of WWR’s selection in Revit modeling, an automatic compliance check software in Revit Modeling is developed to ensure the WWR of Revit model within a reasonable range. The range is given in Design Standard for Energy Efficiency of Public Buildings (GB50189-2015,China). Based on the value range, the enumeration-based WWR compliance inspection software was developed in C# language and integrated into Revit to achieve compliance check on Revit model. Software testing was conducted for a certain office building in Shanghai, China. And Ecotect was used to analyze the thermal environment of unchecked model and checked model, respectively. The result shows that this software can automatically obtain the WWR of each facade of the current model, and determine whether it meets the range of the building location. When a facade does not meet the specification, it can be quickly and automatically adjusted to the appropriate range within the scope. By comparing the Ecotect thermal environment analysis results of unchecked and checked model, it is found that the heating and cooling loads are reduced after the model is checked with intelligent algorithms.
Study on the cooling energy saving potential of a novel radiative cooling paints in building application
Authors: Jiang Kaiyu , Zhang Kai , Shi Zijie , Li Haoran
Published: August 2022

Passive radiative cooling technology has attracted much attention for its ability to obtain “free” cooling by heat exchange between objects on earth and outer space through atmosphere window. However, most of the existing radiative cooling materials are prepared in the form of thin films, which limits the application of radiative cooling in building since the films are lacking in scalability and the various building shapes. In this paper, we prepared a radiative cooling paint (RCP) with acrylic resin as the substrate, and mixed with ploymethylpentene (TPX), and silicon dioxide (SiO2). The emissivity of 0.87 and reflectively of 0.92 is achieved in atmosphere window (i.e., 8-13 μm) and solar spectrum (i.e., 0.2-2.5 μm), respectively. To further indicate the cooling potential of the proposed RCP for its building applications, a two-floor single-family house is modeled using EnergyPlus. The cooling energy saving potential of the prepared RCP for applying on different surfaces of the building envelope is analyzed, and the influence factors for the application of RCP is discussed in detail. The results show that a significantly cooling energy saving can be achieved for the buildings painted with the proposed RCP on all surfaces (i.e., roofs and walls) in which the annual cooling energy consumption can be decreased by 15.8-31.2% comparing to the building with typical roofs and walls located at all five climate zones in China.
Study on optimal design of airport control hall ventilation environment based on butterfly software——Taking the design of Sining air traffic control support building as an example
Authors: Jinghan Bai , Xiaojie Wang , Weimin Wang
Published: August 2022

Airport control hall is the key organization of air traffic control system, mainly used to manage various flight activities of the airport. The control hall contains numerous control seats and control personnel. It is particularly important to create a comfortable indoor environment for the control personnel in a high-intensity working environment. But due to the current design code and standard lack for airport control hall and affiliated offices of the requirements of the physical environment, designers often excessive attention to functional requirements in the design and the facade, while ignoring the control hall indoor environment requirement, so the chaos such as plane layout, facade window problems such as unreasonable, As a result, natural ventilation is not smooth, air conditioning energy consumption increases, and indoor comfort is seriously affected.Sining AIR traffic control Support Building is one of the three major air traffic control projects in northwest China during the 13th Five-Year Plan period. In the preliminary design process of the scheme, the design team used Butterfly tool based on Grasshopper software to conduct computer simulation analysis on the natural ventilation condition of the scheme, comb out the optimization design method and conduct comparative verification. Improve indoor comfort, reduce building energy consumption, and finally summarize the air traffic control hall design strategy adapted to Sining’s unique natural environment, which provides reference for other air traffic control support building projects in northwest China.
Field Measurement and Evaluation of Effective Ventilation of Air Shafts in Subway Tunnel
Authors: Qu Haibo , Zang Jianbin , Wu Yan
Published: August 2022

The ventilation performance of air shaft is important to the air quality of subway tunnel, but there lacks of unified evaluation index of ventilation performance. In this paper, the air shafts at different locations in subway tunnel were taken as research objects, and the wind speed of each air shaft was tested. The effective ventilation volume of air shafts was defined to evaluate the ventilation performance. It was found that on average, during the subway train serve once, the station air shaft in train-arriving side can discharge 2050 m3 dirty air in the tunnel and inhale 218 m3 fresh air from the outside environment, while the station air shaft in train-leaving side can absorb 2430 m3 fresh air, but can hardly effectively discharge dirty air; meanwhile, the middle air shaft can not only effectively exhaust 1519 m3 dirty air, but also absorb 7572 m3 fresh air. And the middle air shaft has better ventilation performance if its inner opening set on the top rather than on the side of the tunnel. This research can provide guidance for ventilation performance evaluation of subway air shafts and reference for the subway tunnel air shaft location design.
Dynamic evolutions of traffic wind influenced by ambient wind for urban road tunnel with shafts
Authors: Huang Weihao , Tong Yan , Lv Gangyu , Dai Baolian , Peng Tao
Published: August 2022

Urban road tunnels with shafts have been applied in some cities in China. Field measurements of Mofan Road Tunnel show that ambient wind is widespread and its influence on the ventilation efficiency of shaft is unclear. In this paper, the physical model of a three-lane 210 m (length) *12 m (width) *6 m (height) tunnel is studied, with three vehicles in each lane and a speed of 60 km/h. Three-dimensional CFD simulations on a 210 m long tunnel with double shafts is carried out by Fluent 6.3.26. Momentum equation and k-ε equation turbulence model are used for simulation analysis and dynamic grid technology is used to simulate vehicles driving. It is found that the ambient wind in tunnel has great influence on the flow field in tunnel and shaft. Number Ri is defined as the ratio of horizontal inertia force to vertical inertia force, revealing the conversion of horizontal inertia force to vertical inertia force.
The Evolution Characteristics of Soil Heat Storage of the Sidewalls in Subway Stations with Years
Authors: Zeng Xianming , Wang Lihui , Zou Xuecheng , Yin Liyuan , Cheng Jian
Published: August 2022

The long-term evolution characteristics of the heat reservoir of soil have been analyzed by 15 years of simulation test with periodic indoor and outdoor air temperature conditions. A scale model test of the soil in the subway station sidewalls and software ANSYS fluid-structure coupling heat transfer model are built in this study, which are complementary and mutual authentication. In 1∼15 years, the results show that the maximal temperature rise of soil at 2 m buried depth is 3.9 °C, at 7 m buried depth is 1.6 °C, and at 12 m buried depth is 1.5 °C. On the sidewalls surface the average maximal endothermic heat flow density is 6.8 W/m2 in summer, and the average maximum exothermic heat flow density is 11.3 W/m2 in winter. It provides theoretical reference for the reasonable use of heat storage of the soil in the sidewalls of subway stations.
Experimental study for humidification performance of air-to-water type hollow fiber membrane humidifier
Authors: Jo Su-Young , Kang Yong-Kwon , Lee Gyu-Bae , Joung Jae-Won , Jeong Jae-Weon
Published: August 2022

In this study, a water-to-air type hollow-fiber membrane humidifier was built, and its humidification characteristics were experimentally investigated under various test conditions. A humidification module made of a porous hollow-fiber membrane in which hydrophilic and polymeric raw materials are mixed was used. Using the selected material, shell-and-tube structured hollow-fiber membrane module was fabricated and tested under various operating conditions. The experimental data showed that the proposed membrane modules exhibited 74.5%–91.7% humidification effectiveness and moisture transfer of 2.5–15.8 g/kg under various operating conditions; furthermore, the modules could provide humidifier performance with few temperature changes. The results of the parametric analysis indicated that the inlet water temperature was a critical factor affecting the humidification heating performance of the proposed system but did not show a clear effect of the water flow rate.
Field test and numerical study on effective dehumidifying zones for a dehumidifier
Authors: Zhang Jing , Li Angui
Published: August 2022

The problem of moist conditions has always been a challenge for humid Underground Spaces. Field test and numerical simulations of two plants in the Underground space are performed, one of which has independent dehumidifiers. The results reveal that the relative humidity can be 12.94% lower, and its average temperature is increased by 1.5°C with the independent dehumidifier added. The thermal and humid environment can be improved to a certain extent. A definition for the effective dehumidifying zone radius of the dehumidifier is presented. Its effective dehumidifying zone is studied. The maximum effective dehumidifying zone radius is approximately 5.0 m at the studied conditions. This outcome can aid in the design of dehumidifiers for HVAC engineers.
Field measurement of thermal environment and air pollution level inside an urban road tunnel during the evening rush hour
Authors: Yu Kongfei , Yang Yong , Chen Jiale , Xu Lin
Published: August 2022

Some urban road tunnels serve as the main traffic access routes for residents in the surrounding large communities. The traffic congestion is a common phenomenon during rush hours inside this kind of tunnel. In order to learn about the environmental parameters inside tunnel during the evening rush hour, a comprehensive measurement in a typical commuting tunnel is conducted. The thermal environment parameters and air pollutant distribution along the tunnel are measured simultaneously. The results show that the traffic volume, vehicle speed and air velocity inside tunnel take on the obvious temporal and spatial discrepancy. There are the average 4.58°C air temperature rise and 96μg/m3 PM2.5 concentration rise from the tunnel entrance to the tunnel exit. The PM2.5 concentration at the tunnel exit is about 2.67 times of the 24-hour average limit of Chinese standard. The rise gradients of the air temperature and PM 2.5 concentration during the evening rush hour is given out.
Performance of smoke confinement during fire accident in subway station
Authors: Luo Na , Gao Le , Liu Xiangwei
Published: August 2022

Fire accidents often lead to tremendous losses and smoke has been reported to be the main cause of these heavy casualties. Accordingly, smoke movement can influence escape and smoke confinement is particular significant. Fire Dynamics Simulator software (FDS) was utilized to carry out complementary full scale numerical simulations of fire accident in a subway station. Different measure of smoke prevention and exhaust were adopted and the difference of smoke confinement among the measure was compared. According to the smoke temperature, hung wall had a good role during early stage of fire accident. However, the performance became worse with smoke accumulation. If the hung wall were adopted, smoke was exhausted from basement 2 and air was supplied into the basement 1 at the same time, the efficacy of smoke confinement was the best. The mechanical exhaust rate had obvious implications for the smoke diffusion.
Train-induced unsteady airflow (TIUA) characteristics of track area in subway station with platform screen doors (PSDs)
Authors: Zhang Xin , Yang Changqing , Ren Xiaofen , You Zhanping , Li Angui , Ma Jiangyan
Published: August 2022

Train-induced unsteady airflow (TIUA) has a great effect on the ventilation and thermal environment of a subway line. Track area, connecting tunnel with station, is the source of the TIUA acting on subway station. Exploring the TIUA characteristics of track area contributes to utilizing the TIUA for improving the tunnel and station environment. In this study, a 1D numerical model according to an actual subway line was established by IDA Tunnel software, to analyse the TIUA rates through the inbound and outbound ends of track area in the PSDs subway station. Four key factors, namely, train arrival time interval between both tunnels, train interval, operation modes of piston vent shafts and bypass ducts, were analysed. The results demonstrate that the TIUA rates of track area in PSDs subway station (bypass ducts closed) are mainly affected by the train driving in this tunnel. The TIUA rates of track area decreases about 36%∼41%, as the train interval increases from 180 s to 540 s. By adjusting the operation modes of piston vent shafts, the change of TIUA rates of track area can reach up to about 13%∼27%. By opening bypass ducts, the TIUA rates of track area decreases by 42%∼50%.
Simulation and optimization research on the induced ventilation system in Peacetime of civil air defense underground garage combined with peacetime and wartime
Authors: Wang Zongwei , Yu Hongchuan , Ji Ping , Wang Haijian , He Weijia , Yin Zizhuang
Published: August 2022

Civil air defense construction advocates the combination of peacetime and wartime. Under this background, according to the needs of civil air defense planning, many underground garages take into account the requirements of civil air defense projects in their construction. The ventilation system of civil air defense underground garage combined with peacetime and wartime is related to the air quality in the garage in peacetime and the safety of masking personnel in wartime. The evaluation and optimization of the ventilation system performance is very important. In the Peace Age, the ventilation system of civil air defense combined with peacetime and wartime works more in peacetime. This paper takes an underground garage of civil air defense combined with peacetime and wartime in Jinan, Shandong Province as the research object. By using computational fluid dynamics (CFD) technology and actual working conditions in peacetime, the numerical simulation of airflow organization and pollutant CO concentration field during ventilation of ductless induced system in underground garage is carried out, and the distribution characteristics of airflow organization velocity field, temperature field and CO concentration field in garage are analyzed. The results show that the optimized induced ventilation system of civil air defense underground garage combined with peacetime and wartime can effectively dilute and discharge CO and other pollutants in peacetime, play a good ventilation effect, and make the air distribution of underground garage more uniform, achieving the purpose of improving and optimizing the air quality of the underground garage. As a result it has a good promotion prospect.
Numerical Simulation of the Human Microenvironment Around the Occupants
Authors: Conceição Eusébio , Conceição Mª Inês , Lúcio Mª Manuela , Gomes João , Awbi Hazim
Published: August 2022

In this study the numerical simulation of the human microenvironment around the occupants is carried out. This numerical work is made inside a virtual chamber, used as classroom, considers the ceiling mounted localized air distribution systems built with one inlet and one exhaust system. The virtual chamber has twelve chairs, each occupied by a virtual mannequin, and six tables. The software, developed by the authors, considers a differential CFD, an integral Human Thermal Modelling and an integral Building Thermal Modelling numerical model. The inlet and exhaust ventilation systems promote, respectively, a downward airflow and an upward airflow in the occupied zone. The study, made in winter conditions, evaluates the thermal comfort, the indoor air quality, the Draught Risk, the Air Distribution Index and Air Distribution Turbulent Index. The results obtained in this work allow us to infer that the thermal comfort, indoor air quality and Draught Risk are acceptable according to what is proposed in international standards.
Fluence of different heating charging modes on thermal comfort in cold area
Authors: Xie Linxiao , Yan Haiyan , Shi Fangning , Li Meng , Lu Dongyu , Cheng Cheng
Published: August 2022

A residential residence in Jiaozuo city, Henan Province, China was researched over two heating seasons, interior thermal environmental characteristics were monitored, and subjects ’ thermal comfort was investigated to evaluate the differences between different heating charging techniques. Charging by area (CBA) and charge by flow (CBF) is the two heating charging types used in China’s central heating buildings. CBA mode is based on the actual home heating area calculation cost, which requires residents in the heating season before the commencement of a one-time settlement of all costs. In contrast, CBF mode is based on the actual residents daily heating charge dosage in real-time. As opposed to CBA mode, CBF mode gives homes greater choice in determining whether or not to utilize heating and gives them more control over the thermal environment. Through comparison analysis, the researchers discovered statistically significant changes in garment insulation, thermal response, and thermal preference across users with different thermal assessment techniques. Households charged by flow rate have a lower thermal neutral temperature and tolerable temperature than those charged by area. CBF mode may lower people ’s expectations of hot settings while increasing heating comfort, which is more favorable to energy conservation and carbon reduction. The goal of this study is to find out how people’s thermal responses alter when they use different heating charging modes, and to utilize this information to help individuals choose the right heating charging mode for their home.
Effect of indoor air temperature on thermal sensation with seasonal variation
Authors: Cheng Cheng , Yan Haiyan , Gao Jingyuan , Shi Fangning , Lu Dongyu , Xie Linxiao , Sun Zhen , Yuan Guodong
Published: August 2022

In order to understand the changes in human thermal sensation in different seasons in cold regions. The data on skin temperature and indoor environmental parameters(of the head, back, chest, upper arm, forearm, hand, thigh, calf, and ankle)were obtained by field test and questionnaire survey in four seasons. The results showed that the parts which had the greatest influence on thermal sensation were different in different seasons. Spring forearms have the greatest most significant on overall thermal sensation. The palm has the greatest influence on the overall thermal sensation in summer. In autumn, the calf has the greatest influence on the overall thermal sensation. In winter, the back has the greatest influence on the overall thermal sensation. The local thermal sensation varies in different seasons under the influence of physiological and environmental factors, so careful consideration should be given to improving people’s thermal sensation in different seasons. In different seasons, affected by individual differences, the thermal comfort of the whole body is lower than that of all parts of the body. This study can provide a theoretical basis for people to obtain higher thermal sensations in different seasons.
Actual measurement and analysis of winter thermal environment of a graduate student studio in Shenyang based on Airpak numerical simulation
Authors: Feng Guohui , Zhou Ziqiang , He Yong , Song Jiasen
Published: August 2022

This paper takes a graduate workshop in shenyang as the research object, and uses Airpak software to conduct numerical simulation analysis on the air distribution and thermal comfort of the fan coil side air supply mode in winter. The measured air supply temperature is 25°C, air supply speed in the x direction for 0.8m / s, 1.5m / s and 2.3m / s three gears, from east to west up to back air supply 3mode. With the increase of air supply speed, the temperature of the working area gradually increases, and the wind speed increases. PMV index and PPD index were used to evaluate the indoor comfort under the three air supply speeds. The air sup 3ply speeds of 1.5m/s and 2.3m/s can meet the requirements of indoor comfort. According to the distribution of personnel, 18 measuring points were set for measurement. The comparison between the simulation results and the measured results showed a consistent trend, which verified the feasibility and accuracy of Airpak for indoor thermal environment comfort analysis.
The combination of earth-to-air heat exchanger (EAHE) and phase change material (PCM) for indoor thermal environment regulation
Authors: Guo Xin , Wei Haibin , Yang Dong
Published: August 2022

The research and application of energy-saving technologies in buildings is receiving increasing attention. Phase change materials (PCM) is an effective passive cooling technology in the regulation of indoor thermal environment. However, in hot-summer and cold-winter regions, the high ambient air temperature makes it difficult to reduce PCM temperature to the phase change temperature in summer. Earth-to-air heat exchanger (EAHE), as an effective energy-saving ventilation technology, in combination with PCM can improve indoor thermal comfort. We performed full-scale experiments to investigate the combination of EAHE and PCM for indoor thermal environment regulation in a typical hot-summer and cold-winter region of China. After 24 hours of continuous operation in summer, variations in ambient and EAHE outlet air temperature range from 28.50 to 44.52 °C and from 22.78 to 24.78 °C respectively. EAHE can effectively precool fresh air, and its average cooling capacity and coefficient of performance (COP) are 1823.03 W and 16.6. The combination of EAHE and PCM has positive impacts on the regulation of indoor thermal environment. The indoor air temperature is in the 22-28 °C range for 69.0 % of the 24 h, and peak indoor air temperature is 31.14 °C. The hybrid system has a TDR of 0.84.
Preliminary Study on Influence of Outdoor Trees on Natural Ventilation of Teaching Buildings
Authors: Niu Shengnan , Wang Annan , Jin Xing
Published: August 2022

The emphasis of this study lied in the impact of tree planting spacing around the teaching building on the indoor wind environment. CFD simulations of the indoor wind environment of teaching building affected by trees were performed utilizing the ANSYS Fluent software using the standard k-ε model with additional source terms. Deciduous broad-leaved trees and coniferous trees were selected as representative tree species for comparison. Five different tree planting spacings were arranged outside the teaching building, and the indoor airflow velocity distribution and pressure distribution were simulated. Then the effects of these different tree layout forms on the indoor ventilation efficiency of the building were compared and analyzed. The results showed that the sum of the total ventilation flow rate in the classrooms rose with the increase of the spacing between trees. However, due to the different location relationship between the tree canopy and the classrooms, the ventilation efficiency of each classroom showed differences. As for tree species, the blocking effect of tall deciduous broad-leaved trees on indoor ventilation was more obvious than that of coniferous trees. This study will have guiding significance for the layout design of vegetation around the building and creating a good indoor ventilation environment.
Impact of shading louvers on wind-driven single-sided ventilation in a multi-storey building
Authors: Zheng Jianwen , Tao Qiuhua
Published: August 2022

As a passive building energy-saving technology, shading systems are usually used to reduce the solar radiation into the unit and reduce the energy consumption of air conditioning system. For multi-storey buildings, shading devices can not only change the indoor thermal environment, but also change the indoor wind environment and air quality because their impact on airflow patterns of natural ventilation. In this paper, the numerical simulation method was used to investigate external shading louvers on the single-sided ventilation performance and indoor air quality of units at different positions in a multi-storey building. Three approaching airflow directions and three rotation angles of louvers were considered and analysed. The results show that the evaluation of ventilation performance of shading louvers in multi-storey buildings is important for shaded buildings, which provide a new perspective for the geometry design of shading louvers and ventilation design of buildings.
A 3D source localization method based on whale optimization algorithm: Experiments for locating a time-varying source in a dynamic indoor environment
Authors: Liao Yu , Lu Jingyu , Cai Hao , Zhang Biao , Li Fei , Zhou Bin
Published: August 2022

To solve the problem of pollutant source localization in an indoor environment with dynamic mechanical ventilation better, this paper designed and built a 3D source localization system composed of three 3D source localization robots whose sensors can move under control in the height direction (0.5 m–1.5 m). Through adopting the 3D source localization system, we realized the application of the previously developed the improved whale optimization algorithm (IWOA) method in 3D source localization and proposed the 3D_IWOA method. To validate the feasibility of the 3D_IWOA method and compare the performance of the 3D_IWOA method and other three 3D source localization methods (the 3D_SPSO, 3D_WUⅡ, and 3D_IPSO methods), each method repeated 15 independent experiments in a Training-Center under the same conditions, respectively. For locating the periodic source at a height of 1.05 m in the downwind zone of this environment, the numbers of successful experiments of the 3D_SPSO, 3D_WUⅡ, 3D_IPSO, and 3D_IWOA methods were 5, 6, 11, and 13 (the success rates were 33.3%, 40.0%, 73.3%, and 86.7%), respectively. In addition, the means of total steps of the 3D_SPSO, 3D_WUⅡ, 3D_IPSO, and 3D_IWOA methods were 36.29 steps, 35.96 steps, 31.75 steps, and 38.15 steps, respectively.
Buoyancy Combined with Buildings Layout Effects on the Thermal Diffusion under Background Wind: Wind Tunnel PIV Measurement
Authors: Zhang Xuedan , Han Dongliang , Zhang Tiantian , Tan Yufei
Published: August 2022

The temperature in the urban areas are higher compared with rural areas because of the UHI effect. The wind-driven ventilation play a significant role on the heat removal. Moreover, the air velocity in the urban areas is influenced by the background wind speed, the exposure of heated surfaces and building layout. However, available experimental data for the thermal diffusion mechanism of different heat source conditions and building layout is limited. Aim at the problem above, the thermal diffusion mechanism of different surface heating conditions and building layout was analysed by conducting wind tunnel experiment with PIV system. To investigate the thermal diffusion mechanism, the building façade, impervious road surface, and traditional roof are heated up three different temperatures to induce buoyant. The effects of three different buildings layouts on flow and temperature also were investigated in this paper. The results showed that building layouts had a marked impact on the flow field near buildings. The terraced building layout is best for heat removal. This study improves understanding of how the buoyancy and wind speed influence the thermal diffusion in different buildings layouts, expands experimental database under different surface temperature conditions and buildings layouts in wind tunnel experiments with PIV.
An experimental study on concentration field reconstruction of indoor pollutant based on mobile monitoring
Authors: Li Dechang , Zhang Biao , Cai Hao , Zhou Suwan
Published: August 2022

Concentration field reconstruction (CFR) refers to the use of the collected spatio-temporal discrete concentration data to reconstruct the concentration field that can reflect the spatio-temporal distribution of pollutants according to certain rules, which is of great significance to ensure the safety of indoor environment. In this paper, using alcohol as the release source, and the field reconstruction experiment based on mobile robot is carried out in an environmental chamber with two types of ventilation: side-up-supply-and-side-down-return, and top-supply-and-side-down-return. Using the experimental data, the performance of Kernel DM+V/W+ method is compared with the other two internationally recognized Kernel DM+V method and Kernel DM+V/W method in field reconstruction and source location from the perspective of qualitative and quantitative. The comparison results show that the Kernel DM+V/W+ method not only has better field reconstruction performance, but also has better source localization performance.
Prediction Method of Steady Concentration of Passive Contaminant in Ventilation System with Air Recirculation: Contaminant released in the air duct
Authors: Liu Yu , Liu Yemin , Shao Xiaoliang
Published: August 2022

When the hazardous substances are released in the air duct of the ventilation system, they are transported into the room through the supply air inlets, causing harm to indoor personnel. In the ventilation system with air recirculation, the contaminant entering the room is recirculated to the ventilation system through the return air outlet, and then affects the contaminant concentration in supply air, making it difficult to be determined. In this work, a method is proposed to predict the steady concentration of passive contaminant when the contaminant is released in the air duct. The method is based on the fixed flow field in the room. The lumped parameter method is utilized to establish the relationship between the concentrations of contaminant in the inlet and outlet for each air duct and the air handling unit. The linear superposition relationship based on the accessibility index is adopted for the steady concentration at an arbitrary position in the room. The proposed method is compared with the prediction with the lumped parameter method in the room. It can rapidly predict the contaminant distributions in all the rooms supplied by the ventilation system with air recirculation.
Numerical analysis on temporal size change of expiratory droplets by considering component variation
Authors: Bu Yunchen , Ooka Ryozo , Kikumoto Hideki , Oh Wonseok
Published: August 2022

When conducting computational fluid dynamics (CFD) simulations to investigate the evaporation characteristics of respiratory particles, the over-simplification of droplet compositions may cause inaccuracies in the results. Although some researchers have conducted parametric studies on droplet components, an investigation using CFD simulation is still lacking. Therefore, this study aimed to determine the effect of different components on the temporal size change of expiratory droplets using CFD simulation. Two droplet sizes (10 μm and 100 μm) were selected, and two types of component combinations were considered, both with a volume fraction of 98.2% for water and 1.8% for non-volatile parts. In Scenario 1, the non-volatile part is composed of NaCl (density: 2200 kg/m3, molecular weight: 58.5 kg/kmol), whereas in Scenario 2, the non-volatile part is composed of NaCl, KCl, lactate, and protein (density: 1000 kg/m3, average molecular weight: 293 kg/kmol). Computations were conducted under constant temperature (25 °C) and different relative humidity (0 and 90%). The results showed that the equilibrium size and equilibrium time were strongly dependent on the droplet components. In subsequent investigations, the effects of different droplet components should be considered in the CFD simulations to obtain more accurate results.
Influencing factors of air volume in kitchen cooking exhaust shaft systems of high-rise residential buildings
Authors: Yu Minghui , Huang Kailiang , Feng Guohui , Hou Xu
Published: August 2022

This paper uses mathematical model theoretical calculation and experimental verification to study the pressure distribution inside the residential kitchen flue and the flow rate of each user through three aspects: temperature difference, opening rate and hood performance. Based on fluid network theory, the flow equation of oil smoke in the cooking exhaust shaft system is established. The accuracy of the mathematical model model was verified through experiments and applied to the calculation of the flue in the kitchen of a 30-story residential building in Shenyang. The results show that the static pressure decreases continuously with the increase of floor height, and the highest pressure appears at the lower level of the floor. The pressure keeps rising as the opening rate increases, i.e., the more users open, the higher the pressure at the bottom floor. Under the joint action of thermal pressure and flue resistance, the static pressure shows a low-high-low distribution form, with the temperature difference increases, the maximum static pressure in the flue moves to the bottom; the flow rate of users on each floor increases with the height, and decreases with the increasing rate of opening, under the influence of thermal pressure user flow distribution is high-low-high distribution.
Inverse identification of source location in a single-sided natural ventilation building
Authors: Zhang Fuyao , Dai Yuwei
Published: August 2022

Natural ventilation is a common way of ventilation for urban residents, which is simple and energy-efficient. However, this ventilation not only introduces fresh air from outdoors into the indoor environment but also brings various pollutants from outdoors into the indoor environment, thus reducing indoor air quality and causing a series of human respiratory diseases in severe cases, such as asthma, pneumonia, bronchitis, etc. In a high-density urban environment, the proximity of rooms within a building can easily lead to cross-infection between occupants in the event of a public health emergency. Therefore, it is of great significance to quickly and accurately find the source of viruses or pollutants. The objective of this study is to accurately locate pollutant source which spread between units by wind effect. A model with three-storey building of wind-driven single-sided ventilation was built. Carbon dioxide (CO2) was used as a tracer of indoor pollutants. Computational Fluid Dynamics (CFD) is used to accurately simulate and predict airflow and concentration fields in and around the building. The results indicated that the location of the predicted pollution source is close to the position where the pollutant is released. The results of this paper can provide vital information for preventing the spread of contaminants in buildings.
Vertical distribution characteristics of outdoor particulate matter concentration in high-rise buildings during working days and non-working days
Authors: Niu BoWen , Fan Yuesheng , Zhang Xin , Wang Huan , Zhou Peitao
Published: August 2022

With the acceleration urbanization in China, it is great significance to understand the distribution characteristics of outdoor particulate matter concentration in high-rise buildings during working days and non-working days. In this paper, a high-rise building of different heights (1, 7, 11, 17, 23, 27) in a university in Xi'an is tested and analyzed. The test times are 8:00, 14:00 and 21:00 respectively. The results showed that the change trend of the particulate matter concentration with the increase of vertical height is the same at all times of the non-working day. While the change trend of particulate matter concentration with the increase of vertical height is basically the same at other times except 8:00 on the working day. In addition, the concentration of particulate matter on working days increased significantly compared to non-working days, with the largest increase at 14:00. On non-working days, PM1.0/PM10 and PM2.5/PM10 both showed a trend of first increasing, then decreasing, and then increasing in different time periods. On weekdays, PM1.0/PM10 and PM2.5/PM10 all showed a trend of falling first and then rising in different time periods. This article provides a reference for the development of high-rise buildings and the effective control of particulate matter concentration in high-rise buildings.
Do room air temperature and human activity affect the particle concentration under real surgical procedures in operating rooms with mixing ventilation? - An experimental study at St. Olavs hospital
Authors: Bi Yang , Fečer Tomáš , Lundøy Runar , Kazemitalachi Tina , Stenstad Liv Inger , Edvardsen Sara , Cao Guangyu
Published: August 2022

The objective of this study is to explore the effects of different room temperatures and different types of activities on the indoor air quality in the operating room during surgery. Three mock-up surgeries were performed at 21 °C, 23 °C, and 25 °C at St. Olavs hospital in Norway. The effects of the surgeon’s activity and nurse's movement on the concentration of particulate matter at the surgical site and instrument table were compared. The results show that the concentrations of particles at both the surgical site and the instrument table are the lowest at room temperature of 23 °C. The activity of the surgeon was the main factor leading to the increase in the concentration of particulate matter with the size 0.3-0.5 μm at the surgical site, while the nurse movement led to the increase in the concentration of particulate matter with the larger size. At all room temperatures, the movement of the distribution nurse had a greater effect than the activity of the surgeon on the increase of the concentration of particles at the instrument table. In addition, the intensity of the particulate source may be factors affecting the concentration of particulate matter. Therefore, it is recommended that distribution nurses should avoid unnecessary activities during the operation.
Advanced ventilation chair for source control of respiratory infectious diseases
Authors: Lin Chen , Ai Zhengtao
Published: August 2022

Since the outbreak of the new crown, a large number of people at home and abroad have been infected, causing great damage to human lives, the economy, and the whole society, which has led to a great deal of concern about respiratory infections. Hospitals are at high risk for the spread of respiratory infections, and hospital outpatient rooms are a focal point for the prevention and control of nosocomial infections due to the small space and frequent visit of many people, where effective measures can greatly reduce the risk of the spread of respiratory infections. Airborne transmission is generally controlled by strengthening ventilation and dilution. However, full space dilution ventilation is less effective in removing exhaled droplet nuclei and is limited by the capacity of the ventilation system and other conditions. Therefore, airborne transmission is a weak section in hospital infection prevention and control, and there is an urgent need to develop advanced technical means aiming for source control. In this paper, computational fluid dynamics (CFD) simulation was used to study the interaction between exhaled airflow, thermal plume, and ventilation airflow when patients stayed in the outpatient consulting room for a short period (from a few minutes to more than ten minutes). After comparing the two styles of wearing mask, it was determined that only the top exhaust was the best distribution form. When patient wear face masks, the top exhaust with ventilation volume rate of 20 m3/h can achieve 90% collection efficiency in 30 s. After the patient left, it takes only 15 s to collect most exhaled particles. The air volume and vent dimension is important to the design of ventilation plate, when the design is not reasonable, it can cause up to 50% impact. This paper propose a personalized ventilated chair for airborne transmission which could contribute new solutions and technologies to achieve the goal of significantly reducing hospital infection rates.
Influence of different air distribution on ventilation effectiveness in negative pressure hospital wards
Authors: Li Zhengrong , Feng Yanbo , Zhu Han , Feng Xiwen , Fan Xueke , Yu Yize , Sun Xiangyu
Published: August 2022

Hospital ward is one of non-negligible potential places to occur cross-infection among patients and health workers. Air-borne transmission was regarded as the main infection route of the SARS-CoV-2. Preventing the air-borne transmission should be a significant measure, which could effectively mitigate the risk of the virus infection. Based on those consideration, in this study, the influence of different types of air distribution on ventilation effectiveness was modeled through Computational Fluid Dynamics (CFD) simulations. Several typical negative pressure wards same as the ward in Wuhan Thunder God Mountain hospital and conformed to the Chinese National Health Commission (NHC) guidelines were modelled. We simulated the influence of different locations of air supply inlets, analysed the influence of the buffer door and compared the contaminant concentration on different entry route for health workers. The results show that the air distribution required by NHC guidelines could retain a directional airflow from the bed-zone to the toilet, which also has a better accessibility of supply air, and health workers are safer to avoid standing closed to the air exhaust outlet in the downstream area of pollutants during ward rounds.
The dynamic partitioning of airborne phthalates in indoor environment: effects of ventilation
Authors: Bu Subei , Wang Yanling , Wang Haiyan , Wang Fang , Tan Yufei
Published: August 2022

Low energy consumption buildings with strong air tightness such as passive buildings are the development trend in the world. However, ventilation directly affects the emission and dynamic transport of indoor phthalates. A transient partition model considering the dynamic behavior of size-resolved particle was utilized to investigate the influence of ventilation on the airborne Di-2-ethylhexyl phthalate (DEHP). The air exchange rate (a) was set to 0.15 h-1, 0.3 h-1, 0.6 h-1, 2h-1 for the different conditions. The predicted gas-phase concentration of DEHP in the initial 70 days is unaffected for different a and constant hms, whereas it raises until the a increases to 2 h-1. The equilibrium gas-phase concentration decreases from 0.257 to 0.203 μg/m3. Meanwhile, the higher a also reduced the particle-phase concentration of DEHP. Furthermore, the changes of airborne DEHP were analyzed by considering the impact of a on hms caused by ventilation. The results indicates that more ventilation leads to higher gas-phase concentration for the whole stage. The gas-phase concentration at equilibrium increases from 0.237 to 0.440 μg/m3. The total airborne (gas-phase + particle-phase) concentration decreases with the higher ventitation rate, which indicates that the ventitation has a positive effect on indoor airborne DEHP.
Characteristics of indoor ozone pollution in residential buildings based on outdoor air pollution
Authors: Jing Lijun , Wang Jun
Published: August 2022

Ozone pollution can not only cause serious effects on human respiratory tract, lung, cardiovascular and immune system, but also lead to secondary pollution of indoor air environment by reacting with human surface sebum, building materials surface and other indoor compounds. As people stay indoors for more than 90% of their time, indoor ozone exposure is far more harmful than outdoor ozone exposure. Indoor ozone mainly comes from the outdoor environment. Therefore, it is an important prerequisite for controlling indoor ozone pollution to master the characteristics of indoor ozone pollution concentration under the influence of outdoor air pollution. The outdoor ozone concentration of 20 representative cities in the five climatic areas of China were investigated in this study. Meanwhile, indoor ozone concentration was predicted based on I/O ratio (indoor-outdoor concentration ratio). Furthermore, the indoor ozone pollution level affected by window opening time, air change rate and ozone deposition velocity was analyzed. The results show that the increase of air change rate and window opening time leads to the rise of indoor ozone pollution level. Moreover, the growing up of ozone deposition velocity may cause more ozone to be removed by the indoor surface, then the indoor ozone concentration decreases. In addition, indoor ozone pollution is the most serious in cold zone and the least serious in mild zone.