bluuebunny/crossref_metadata_2025 huggingface dataset:
Field study on human thermal comfort and indoor air quality in university dormitory buildings
Authors: Zhao Shengkai , Yang Liu , Gao Siru , Zhai Yongchao
Published: August 2022

Field studies on the environmental conditions and occupant thermal comfort were carried in air-conditioned buildings and no air-conditioned building in Xi’an, China. The present study aimed to explore the effect of indoor thermal history on the thermal adaptation and indoor air quality of occupants. Based on a field study, 550 and 580 data sets were obtained in naturally ventilated (NV) and spilled air-conditioned dormitory buildings (SAC), respectively. The physical environment parameters and subjective responses were explored. Most of the environment in NV mode were warmer than the current standard upper limit (28 °C). The neutral temperature of the NV group was 26.7 °C, 1.5 higher than that of the SAC group (24.6 °C). The upper limit of 80% acceptable temperature range was 29.2 °C for the NV group, 1.7 °C higher than that of the SAC group (27.5 °C). Compared to the SAC group, a warm indoor thermal history of the NV group produced a shift to higher neutral temperature and higher acceptable temperature. Differences were found in the indoor environment quality and in the occupant’s subjective satisfaction between the two groups. Compared to PMV model, the adaptive model was more applicable to spilt air-conditioned building.
Improving work efficiency and thermal comfort by negative vertical temperature gradient in heating model of impinging jet ventilation
Authors: Pan Bing’an , Yang Bin
Published: August 2022

In heating model, impinging jet ventilation (IJV) supplies warm air jet with high momentum which impinges and spread over floor. Thermal stratification in opposite direction (temperature of foot area is higher than head area.) is found in the area near supply opening, because high residual momentum of the jet after impinging can resist thermal buoyancy in a considerable distance on floor surface. Negative vertical temperature gradient was seldom explored. To study how negative vertical temperature gradient affects local thermal comfort and work performance, 16 subjects (8 males and 8 females) were asked to work in a room with three negative vertical temperature gradients (1, 3, 5k/m) between head (1.1 m) and ankle levels (0.1 m). In this study, overall thermal sensation, local thermal sensation of body segments and work performance were collected. The results show that work performance and thermal comfort could be improved by higher negative vertical temperature gradients.
A Study on Air Conditioning Thermal Comfort in Building Atrium in Winter
Authors: Chu Guangming , Xu Tongtong , Sun Yanghong , Li Yang
Published: August 2022

The building atrium is a large space formed by integrating various functions. It runs through multiple floors and is directly or indirectly connected with each floor. In the atrium, people can not only enjoy the air quality of the interior space but also create an open and natural environment characteristic of the outdoor space. In this paper, a winding corridor atrium is the research object, using CFD simulation software to establish a mathematical model. The temperature field, velocity field, and PMV-PPD of the atrium under various working conditions were studied by numerical simulation method, and the thermal comfort of the working area at the bottom of the atrium and the corridor area of each floor were analyzed emphatically. The building atrium is set up in two forms: the upper part is airtight and the upper part is not airtight. Through theoretical analysis and comparison of simulation results, it is concluded that the non-enclosed atrium will help to improve the thermal comfort of the top, and at the same time aggravate the phenomenon of low temperature in the working area at the bottom of the atrium.
A mathematical model of the room temperature dynamic response in multi-zone buildings
Authors: Lei Lei , Huang Shaodan
Published: August 2022

There are many factors that affect the change of room temperature, especially outdoor environmental factors, which makes it difficult to establish a model to describe the dynamic changes of the real time room temperature. In response to this problem, this study proposes a RC network two-node wall structure method to describe and analyze the heat conduction process of the building envelope. With this method, we first divide building envelope such as walls and floors into two-story structures, and then use energy balance theory to establish the energy balance equation of each node. Finally, we obtained the dynamic response equations of room temperature and humidity in each room of the whole building. This method simplifies the complex heat transfer process of the building envelope to a simple mathematical problem. The experimental validation indicated the accuracy of the proposed model.
Indoor thermal environment of kindergarten building: A case study in China
Authors: Yan Qiuhui , Luo JieRen , Li WenLi , Zha PeiQing
Published: August 2022

Based on the building of a kindergarten in Weinan, Shaanxi Province, this paper explores the influence of different envelope structures and heating modes on the indoor thermal environment for the energy saving and thermal comfort of the existing buildings. Using operating temperature as the evaluation index of thermal comfort, the 15 designed schemes were simulated through Energyplus software and actual measurement to obtain the operating temperature change law and annual heating energy consumption value. The envelope structure optimized by choosing energy-saving building materials such as expansion perlite and foam cement is obviously conducive to the improvement of indoor thermal comfort, and the thickness of the insulation layer increases, and the operating temperature increases accordingly; Although the standard effective temperature in intermittent heating mode is slightly lower than that in continuous heating mode, the standard effective temperature rises significantly with the extension of preheating time, which can meet the requirements of thermal comfort.After energy saving transformation, the total heating energy consumption of the kindergarten building is reduced by up to 3644 GJ, and the energy-saving rate reaches 67%.
Approach on prediction of indoor temperature distribution by combining POD, CRI and mobile sensors
Authors: Zhao Yanan , Ding Xiaoxiao , Zhang Weirong
Published: August 2022

In our previous study, a prediction method of indoor temperature distribution based on the Contribution Ratio of Indoor Climate (CRI) and finite air temperature collected by one mobile sensor has been proposed. However, the CRI fixed value hypothesis limits its application in practical situations. In this regard, this study proposes to introduce interpolation POD (proper orthogonal decomposition) method to obtain the dynamic distribution of CRI, so as to improve the prediction accuracy. As a case study, in a simplified CFD model with identified heat source conditions, based on the interpolation POD method, the reconstruction of each sub temperature field dominated by only one heat source under any air supply parameters was realized, and thus its CRI distribution could be calculated. Then, by combining the finite air temperature collected by the mobile sensor, the indoor temperature distribution was predicted. The results showed that the introduction of interpolation POD method is effective, which breaks the application limitations of CRI fixed value hypothesis on the proposed method, and further promotes its development potential in the direction of "real-time prediction and dynamic regulation" in practical application.
Evaluation of an automatic opening window system to maintain adequate ventilation rates
Authors: Tsutsumi Akane , Lee Sihwan
Published: August 2022

Under the influence of COVID-19, it is recommended to ventilate to reduce the risk of infection in the room. In an air-conditioned room, opening windows increase the ventilation rate that caused by indoor and outdoor temperature differences. However, there is a concern that opening windows in the air-conditioned room will increase the heating and cooling loads due to air leakage. In addition, it is difficult to maintain the adequate ventilation rate. To solve this problem, we developed an automatic window opening system to control the natural ventilation rate. This system can be controlling the adequate ventilation rate for the room by adjusting the opening area of window automatically. The purpose of this study is to confirm the effectiveness of this system and to understand its performance. In this study, analysis was done to calculate the adequate opening width in Japan, and actual measurements were conducted to understand the operating performance of this system. As a result, it was confirmed that sensible heat load due to ventilation was reduced with this system, and the ventilation rate could be controlled by this system.
Modification of thermal pressure ventilation model and its predicting on cooling potential of natural ventilation (NVCP) for large space buildings
Authors: Dai Baolian , Tong Yan , Peng Tao , Huang Weihao
Published: August 2022

More and more large space buildings have occurred in China due to its multiple functional zones and architectural aesthetics, but heavy HVAC energy consumptions have been often accompanied. Effective use of natural ventilation may largely reduce the use of chillers during cooling periods. Field measurements were carried out on the large space in Nanjing, a city of south China. It was found out that linear thermal stratifications were evident with the gradients α being in range of 0.1~0.4 °C/m, Traditional thermal pressure ventilation model is modified by introducing solar radiation and vertical temperature gradient. The dimensional neutral plane height Hn/H and the mass flow rates per unit opening area G are calculated out under circumstance of Matlab. Its accuracy is verified by that from energy model software EnergyPlus. Results show that the outdoor temperature has much influence on the α; the dimensionless neutral plane height Hn/H increases with the increasing of α; The change of flow rate is not obvious for the different regions; This study provides theory basis for optimizing design of upper opening for maximum use of natural ventilation in large space buildings.
Study on the dynamic natural ventilation rates of occupied residence
Authors: Liu Shuwei , Jian Yiwen , Zhu Wenbo , Gu Xundong , Bian Mengmeng , Liu Zijia
Published: August 2022

The residential natural ventilation rates have a significant impact on indoor thermal comfort and air quality and building energy consumption. The characteristics of the indoor-outdoor temperature difference and wind pressure change over time, as well as the occupants' window opening behavior and the use of HVAC systems, resulting in the residential air change rate being dynamic with time. Many previous studies of residential ventilation measured the steady-state air change rates, which does not reflect the actual dynamic characteristics. In this study, a field measurement was conducted in a bedroom of one natural ventilation residential building in Beijing with continuously monitoring the CO2 concentration, indoor air temperature, and outdoor meteorological parameters for one year. Using the CO2 released by occupants as a tracer gas, the extended Kalman filter based on the Transient Mass Balance Equation (TMBE) was adopted to calculate the dynamic air change rate. This method can effectively filter the CO2 concentration measurement noise. The trend of air change rate with each influencing factor was analyzed. This study is expected to lay the foundation for future studies of dynamic air change rates in residential buildings.
Research on reverse identification algorithm of indoor pollution source based on machine learning
Authors: Su Xin , Long Zhengwei , Xu Yinyue
Published: August 2022

Indoor sudden pollutant leakage brings environmental pollution and occupational exposure, so it is more and more important to obtain the location and identification of leakage sources. Through the forward method based on machine learning, this paper establishes a reverse traceability model for indoor multiple pollution sources. The POD method is used to obtain a large number of intermediate working condition data. The data pre-processing strategy of first normalization and then random forest feature screening can effectively improve the accuracy and generalization ability of the model. Based on a real environmental room case, model verification and sensor deployment optimization are carried out. The results show that the four sensors deployed in a specific location can achieve more than 95% positioning accuracy. In addition, the leakage possibility ranking component embedded in the model can effectively guide the staff to check the leakage points in turn, and the efficiency of three checks is as high as 99.91%.
Simulatiomn of BHE fresh air air conditioning system based on TRNSYS-CFD Hybrid Simulation
Authors: Hou Xu , Huang Kailiang , Feng Guohui , Hao Yuxiang , Yu Minghui
Published: August 2022

In order to solve the problem of input fresh air overheating (cooling) in the cold supply (heating) season in severe cold regions, a soil source (BHE) combined with fresh air preheating (cooling) air conditioning system was studied in a net-zero energy building in Shenyang. Firstly, a hybrid TRNSYS-CFD simulation model based on TRNSYS and Fluent simulation software was established to simulate the operation and indoor temperature distribution of the air conditioning system in the building during a typical day in the summer (winter) season. The TRNSYS-CFD hybrid simulation allows simultaneous analysis of the operating characteristics of the air conditioning system and the real-time indoor temperature distribution. The results show that the accuracy of the hybrid simulation is compared with that of the TRNSYS stand-alone simulation by monitoring the temperature changes in each room. The room temperature from the TRNSYS stand-alone simulation is the average temperature of the room return air, while the room temperature from the hybrid simulation has a stratification effect and the simulation data is more valuable for reference.
Numerical study on airflow performance and mechanical characteristics of centrifugal fan
Authors: Bai Minkai , Tan Haihui , Liu Zhan
Published: August 2022

As small fans are widely used to dissipate the heat of the electronic components, a series of special requirements are put forward on the airflow performance and stress characteristics. In the present study, the computational fluid dynamics (CFD) method is adopted to study the airflow characteristics of a specific type of fan, including the fluid pressure distribution, flow velocity field and fluid streamline distribution. The stress characteristics of the fan blades are systematically analyzed based on the fluid-solid coupling and thermal-solid coupling methods. The results show that with the rotation speed of 1400 rpm, the airflow velocity in the air duct is unevenly distributed, and some eddy disturbances form and occur in the flow field. To improve the operating efficiency of the fan, appropriate optimization schemes should be adopted to reduce the intensity and range of the eddy influence. When the inlet temperature is 20 °C, the stress on the impeller is mainly caused by centrifugal force and thermal load. As the inlet temperature increases, the effect of the thermal load becomes increasing. While for the centrifugal force, its influence on the impeller gradually disappears and completely disappears when the temperature reaches 50 °C.
Influence of the purification system of machining factories on indoor air quality
Authors: Wang Yukun , Long Zhengwei , Shen Xiong
Published: August 2022

High-concentration oil mists from machining plant equipment can cause serious health problems for workers. The concentration of oil mist is generally reduced by ventilation and purification systems. However, the coupling relationship and interaction between purification and ventilation systems are not well understood. This study is based on an actual machining factory. First, the CFD simulation method was validated by the experimental data. Secondly, the influence of purifier exhaust air and exhaust air direction on oil mist distribution was studied. The results show that the influence of purifier exhaust air cannot be ignored in the prediction of oil mist concentration distribution. The difference in oil mist concentration and oil mist removal efficiency was 24% and 20%, respectively, with and without the purifier exhaust. Compared with the vertical exhaust direction of the purifier, the purifier with horizontal exhaust has fewer areas with higher oil mist concentrations. However, for the oil mist concentration at 1.5 m above the floor, the vertical exhaust air of the purifier is 0.1 mg/m3 lower than the horizontal exhaust air, and the removal efficiency is increased by 6.9%
Boundary layer wind tunnel tests of outdoor airflow field around urban buildings: A review of methods and status
Authors: Zhao Yi , Li Ruibin , Feng Lu , Wu Yan , Gao Naiping
Published: August 2022

Outdoor airflow fields have received increasing attention in the building aerodynamics community due to that the airflow distributions around outdoor buildings are closely related to issues such as thermal comfort, building ventilation, and pollutant dispersion. The focus of this paper is on the airflow distributions around buildings obtained through wind tunnel tests, and such studies are mostly conducted in boundary layer wind tunnel with long test section. This paper reviews current techniques for boundary layer wind tunnel tests of airflow distributions in urban outdoor environments. Then, the characteristics of airflow distributions around buildings in three typical configurations from previous studies (i.e. isolated building, street canyon, and building complexes) are reviewed. This review highlights that the proposed building models should be carefully assessed in combination with wind tunnel tests at the design stage. In addition, it is important to obtain wind tunnel test data for buildings with thermal effects, and the importance of arranging the underlying surfaces during the test is also emphasized.
Construction strategy on outdoor environment of ecological community in dry region–Lanzhou, China
Authors: Ma Hongqiang , Li Anying , Zhang Chune , Ding Ruixiang , Liu Yu
Published: August 2022

In order to improve the human thermal comfort of the ecological community, aiming at the characteristics of low humidity and large wind and sand in northwest areas such as Lanzhou, the method was proposed to improve the human thermal comfort by water evaporation from porous pavement. Firstly, the outdoor environmental model of the ecological community was established and the environmental parameters of a community are simulated by using the model in Lanzhou. The simulation results are compared with the experimental results, and the relative error is less than 15%. Secondly, the change law of outdoor thermal and humid environment is simulated and analysed when porous pavement and ordinary pavement are used in ecological community, respectively. The results show that the humid environment of the community has changed significantly and the maximum change is about 7% after considering the water evaporation from porous pavement. Meanwhile, the amount of single water sprayed onto the porous pavement should meet the water evaporation requirement of 1.67h under the climatic conditions at that time. The above research results provide theoretical guidance for improving the outdoor thermal comfort of residential buildings in dry region.
Simulation Research on Ventilation Control of Gaseous Pollutants in Urban Sentry Boxes
Authors: Li Yanyan , Yin Haiguo , Deng Xin , Liang Linfeng , Zhai Yongchao
Published: August 2022

The tiny spaces of sentry boxes in cities, such as mobile security guards, highway toll booths, etc., are mostly located beside roads with harsh outdoor environments. Due to office demands, work windows often need to be kept or frequently opened. The intrusion of outdoor pollutants through the windows leads to the deterioration of the indoor air quality, and threatens the health of employees. This paper takes the gaseous pollutant NO2 as the representative and discusses the effective ventilation design scheme for improving the air quality in the sentry box with openings using two attached ventilation modes as the carrier. Taking the vertical wall-attached ventilation as an example, the formation of the air curtain at the window hole and its barrier performance to outdoor pollutants were studied. The conclusion is that when the air supply velocity is sufficient to form a complete air curtain at the window hole, it can effectively block the pollutants. The horizontal wall-attached ventilation shows that clean air is delivered to the space with openings, and the indoor air quality can also be well improved due to the dilution effect, but the effect of positive pressure control is not obvious due to the large opening. The conclusions can provide guidance for the ventilation design of sentry boxes with openings.
Various pathogen-laden aerosol deposition in the realistic human airway during inhalation
Authors: Luo Danting , Zheng Xiaohong , Qian Hua
Published: August 2022

Studying the deposition of different pathogens with various sizes and shapes is vital for understanding various respiratory infectious diseases. Few studies focus on the deposition of pathogen-laden aerosol during inhalation, especially for different respiratory infectious pathogens. This paper studied the depositions of H3N2, SAR-CoV-2, Ebola virus, Escherichia coli, and different sizes of droplets in the realistic human respiratory airway during inhalation. And results show that large droplets are mainly deposited in the upper respiratory tract, while most of the small particles, especially viruses, will transmit to somewhere further than bronchi-G7 and be deposited into the deep lobes of the lungs. Over 90% of single virus particles will inhale into lobes. The deposition efficiency of pathogens in the right lobes is significantly higher than that in the left, and this phenomenon is more obvious in the superior lobes, which may also explain why lung carcinomas are more likely to develop in the right lung. Compared with other viruses, SARS-CoV-2 is more inhaled into the right superior lobe, which should be paid attention to. This paper may help learn about various respiratory infectious diseases and provide references for treatment methods and drug delivery locations.
Temporal and spatial aerosol transmission from the exhalation of an infected person in an office environment
Authors: Lestinen Sami , Kilpeläinen Simo , Kosonen Risto , Pasanen Pertti
Published: August 2022

The paper reports office test chamber experiments with an exposed breathing thermal manikin (6 L/min) and an infected exhalation simulator (6 L/min) connected with a thermal dummy. The motivation was to investigate effects of different protection methods at workstation when an infected person is working in the room. The protection methods were room air purifier, personal air purifier, FFP2-mask, and workstation partition panels. The objective was to measure temporal and spatial concentration characteristics at the exposed breathing zone. The exhale of infected model was aerosolized by using a Blaustein atomizer (BLAM), syringe pump and paraffin oil (0.6 mL/h). The concentrations were measured with TSI optical particle sizers. The ventilation method was mixing ventilation from a perforated duct. The indoor air change was 1.7 1/h (ACH). The experimental set-up was carried out at 6 workstations around the infected person. The temporal and spatial evolution was measured from zero concentration to steady concentration level. The results indicate that the room air purifier and the facemask can efficiently reduce exposure whereas the personal air purifier had a moderate reduction. The partition panels had only a minor effect on exposure. The lowest exposure was found when the individuals were sitting at the same side far from each other.
Respiratory infection risk based ventilation and room conditioning design method with year-round thermal comfort control in modern office buildings
Authors: Kiil Martin , Simson Raimo , Võsa Karl-Villem , Mikola Alo , Thalfeldt Martin , Kurnitski Jarek
Published: August 2022

The new decade will be a major challenge for built environment to satisfy building users and owners demands for superior IEQ in the work environment and tackle infection risk issues brought by SARS-CoV-2 pandemic. We collected thermal comfort and IAQ data from modern Estonian office buildings showing that improvements are needed in whole chain of the HVAC science, engineering and manufacturing because current solutions in these buildings have led to many complaints of draught and readjustments of supply air temperature have typically compromised energy performance. To achieve Category II or I IEQ, more systematic design methodologies are needed. Additionally, ventilation rate and air distribution dimensioning based on respiratory infection risk has to be taken into use as a complementary method of existing ones for office space AC and ventilation design, where both net floor area and occupant number define the required ventilation. Based on air velocity and temperature (operative, supply air and local) measurements conducted in five office buildings a new IEQ design methods were developed to satisfy the thermal comfort indices leading to low occupant complaints and not compromising energy performance at the same time. In well ventilated Category I and II office spaces, control of draught risk is an extensive design task for which new methodology was developed. Our method focuses separately on IEQ parameters during heating, cooling and midseason, from which the latter one is the longest and the most dominating one. The design method is presented by connecting thermal comfort and infection risk with ventilation rate. Infection risk based air flow rate selection diagram and corresponding air velocity diagrams for an open plan office and 3-person room showing the possibilities to size ventilation for the event reproduction number of R = 0.5 were constructed.
Simulation study on the effect of air supply and exhaust terminals to coughed droplet diffusion in NPI ward
Authors: Bian Jinlong , Shi Shengjie , Dong Lingling , Liao Chunhui
Published: August 2022

The numerical (CFD) method is applied in this paper to investigate the nonuniformity of temperature and airflow filed, the spatial and temporal distribution of coughed droplet under stratum ventilation and mixing ventilation in the negative pressure isolation (NPI) ward. The influence of exhaust terminals number and location on the diffusion process of coughed droplet is analyzed under heating mode. The results show that the relative pollutant concentration in the breathing area of stratum ventilation is lower than that of mixing ventilation. When the air exhaust terminals are high from the ground and the number are small, it is more conducive to reduce the infection risk of medical staff. The deposition rate and suspension rate of stratum ventilation are higher than that of mixing ventilation, and the escape rate is lower. When the number of exhaust outlets is large and the location is high, the nonuniformity coefficient is the smallest and the deposition rate is the largest, which are 0.668, 0.029 and 91.4% respectively. The escape rate is higher when the number of exhaust outlets is small and the location is high, and the suspension rate is higher when the number of exhaust outlets is large and the location is low, which are 27.9% and 1.11% respectively.
Infection Dynamics of SARS-CoV-2 in Mucus Layer of the Human Nasal Cavity - Nasopharynx
Authors: Li Hanyu , Kuga Kazuki , Ito Kazuhide
Published: August 2022

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the worldwide spread of coronavirus disease-2019 (COVID-19) since its emergence in 2019. Virus replication and infection dynamics after its deposition on the respiratory tissues require detailed studies for infection control. This study focused primarily on SARS-CoV-2 dynamics in the mucus layer of the nasal cavity and nasopharynx, based on coupled computational fluid-particle dynamics (CFPD) and host-cell dynamics (HCD) analyses. Considering the mucus milieu, we coupled the target-cell limited model with the convection-diffusion term to develop an improved HCD model. The infection dynamics in the mucus layer were predicted by a combination of the mucus flow field, droplet deposition distribution, and HCD. The effect of infection rate, β, was investigated as the main parameter of HCD. The results showed that the time series of SARS-CoV-2 concentration distribution in the mucus layer strongly depended on diffusion, convection, and virus production. β affected the viral load peak, its arrival time, and duration. Although the SARS-CoV-2 dynamics in the mucus layer obtained in this study have not been verified by appropriate clinical data, it can serve as a preliminary study on the virus transmission mode in the upper respiratory tract.
Study on static adsorption characteristics of a new reduced graphene oxide air filter material for volatile formaldehyde from glue
Authors: Gan Weikang , Fan Yuesheng , Zhang Xin , Wang Huan , Xue Kexin , Cui Yong , Li Ming
Published: August 2022

Formaldehyde is one of the main indoor pollutants, and living in an environment with formaldehyde for a long time can cause serious damage to the human body. In this paper, non-woven fabrics and new reduced graphene oxide air filter materials were used to perform static adsorption tests on formaldehyde volatilized from glue. The results show that the new reduced graphene oxide air filter material has good formaldehyde adsorption performance, and the adsorption saturation of this material is as long as 4 hours, which is twice that of F6 non-woven fabric. Within 4 hours, the formaldehyde removal efficiency of the new reduced graphene oxide air filter material and F6 non-woven fabric were 15.4% and 2.9%, respectively, and the formaldehyde adsorption was 0.81·10-3mg and 4.32·10-3mg, respectively, and the removal efficiency was improved5.9 times. This paper provides reference and reference value for the adsorption performance of new composite air filter materials on harmful gas pollutants.
Effect of outlet location on indoor air quality for stratum ventilation under heating mode
Authors: Lei Jiangang , Gao Shasha , Liu Yixin , Cheng Yong
Published: August 2022

Warm air supply is widely used to condition indoor environment in winter. It has been proved that stratum ventilation (SV), as a novel air distribution, has potentials to be applied for heating. The outlet location may affect indoor air quality (IAQ) due to interaction between thermal plumes from heat sources and room airflows. In this study, the effect of outlet location on IAQ for SV was investigated for 9 cases under heating mode. The outlets were located at the heights of 0.4 m on the same side wall as the inlet, 0.4, and 1.3 m on the opposite side wall, respectively. The concentration of carbon dioxide was measured in an experimental chamber with dimensions of 5850 mm(L) × 5057 mm(W) × 2554 mm(H). The average concentration of carbon dioxide and carbon dioxide removal efficiency (εCRE) were used as the evaluation indexes. The results showed that the concentration of carbon dioxide in the breathing zone with the outlet located on the same wall as the inlet was lower than those with the outlets located on the opposite side wall. At this scenario, εCRE was greater than one, showing a good ventilation performance.
Quantitative Assessment of Indoor CO2 Concentration of a Comprehensive Office Building
Authors: Wang Lei , Wang Yanling , Wang Fang , Wang Haiyan
Published: August 2022

To better understand the extent of different ventilation strategies, a set of multi-zone models of a comprehensive office building in Harbin were conducted based on CONTAMW. The main purpose aims to assess various factors affecting the concentration of indoor CO2 in real situations by building network models, in order to seek appropriate ventilation control strategies to improve indoor air quality. Firstly, under the combined action of stack effect and wind pressure, the model was verified by field measurement. Secondly, CO2 concentration peak value, attenuation rate and air exchange rate were analysed in conference rooms on different floors under typical seasons with the doors and windows closed. Moreover, different doors and windows opening schedules of conference rooms were set during the meeting to reduce CO2 concentration. Results demonstrate that CO2 concentration in conference rooms are affected by many factors including different climatic parameters, height of building, building envelope leaking characteristics, occupant participated ventilation behaviour etc. and multi-zone simulation analysis shows the necessity of its application at comprehensive building. The study highlights the need for effective guiding significance of ventilation control to reduce the concentration of indoor CO2 in areas where there are more people indoors in short period of time, which is also meaningful for the personnel health and building design.
Indoor environmental quality and pollutant dispersion estimation inside a bus at the downtown areas of Dalian, China
Authors: Zhao Yu , Gu Chenmin , Song Xiaocheng
Published: August 2022

Among most public transport modes, the frequent start-stop urban bus has the most complex micro-environment. Indoor environment quality, airflow patterns, etc. has not been fully understood yet inside buses. In addition, under COVID-19 pandemic, it had been proved aerosol transmission risk might be enhanced inside the buses. Usually, carbon dioxide (CO2) could be considered the index of ventilation effect in enclosed environment, airborne particles are viral carriers. Thus, accurate forecasting of the two abovementioned key pollutants become important. The study analysed the CO2 and airborne particle dispersion inside a bus at the downtown areas of Dalian, China by employing field measurement at spring and autumn, 2021. Temperature, relative humidity, CO2 and airborne particle concentrations were logged by sensors at sampling points respectively, passengers onboard were counted manually. Correlation analysis was conducted and two empirical models for evaluating CO2 and airborne particle were concluded based on the measurement data. From preliminary results, transient concentration of pollutant is almost linearly correlated with cumulative and instant numbers of passenger respectively, with Pearson correlation coefficient larger than 0.8336 for CO2 and 0.8424 for PM2.5. The purpose of the study is to reflect environmental quality inside the bus and provide inspiration into pollution control strategies in buses.
Diffusion of aerosol pollution in residential bathroom under different air distribution
Authors: Ding Baoying , Liu Wei , Yang Minghan , Liu Kailun , Liu Tao
Published: August 2022

In this study, based on the numerical simulation, we investigated aerosol pollution diffusion in residential bathroom with exhaust vents at different positions and different ventilation methods. The results show that setting an air outlet under the side wall next to the toilet can discharge aerosol pollutants in time, which not only shortens the diffusion path of aerosol pollutants, but also optimizes the air organization form. The dry and wet separation of the toilet area and the wash area separated by a physical partition adopts the principle of "screen", which effectively blocks the transmission path of aerosol pollutants.
Combination of UV radiation with 3D structure media filter for indoor air disinfection
Authors: Liu Jiatao , Liu Junjie , Fan Yingying , Wang Pan
Published: August 2022

The ongoing COVID-19 pandemic made us re-realize the importance of environmental disinfection in indoor areas. Several studies have documented that the air purification system combining UV light and high-efficiency particulate air (HEPA) filtration can successfully remove the virus from the air. However, UV light cannot penetrate deep into the HEPA, which causes the pathogens inside cannot be killed. In this study, we analyzed the potential of three-dimensional(3D) filter media combining with UV sterilization for the treatment of pathogen aerosols. Through geometric ray analysis, it is concluded that the transmittance attenuation of 3D filter material is linear, while that of ordinary fabric filter material is abrupt, which means UV light combining with common fabric filter can only kill the microorganisms on the surface. In order to prove that 3D filter with UV irradiation can eliminate microorganisms inside the 3D filter, we carried out an experimental verification. The results of the experiment shows that the bactericidal rate increased with UV dose and the k value is 3.75*10-4, much smaller than that in air UV disinfection. This indicates that although it is more difficult to kill pathogens on the surface of fibers than in air, 3D filter material with UV can kill the pathogens inside.
Prediction of household dust mite concentration based on machine learning algorithm
Authors: Sun Chanjuan , Li Leyang , Hong Shijie , Huang Chen , Li Jingguang , Zou Zhijun
Published: August 2022

Household dust mites (HDMs) are the important allergens causing allergic diseases in children. A predictive model can help us understand the concentration of HDMs in different areas of China to better prevent and control this kind of allergen. This study used 454 household inspection samples in childrens’ room obtained from China, Children, Homes, Health (CCHH) phase 2 study, conducted during 2013-2014. Spearman correlation and multiple logistic regression were used to explore the influencing factors of HDMs concentrations, by comprehensively considering residents’ lifestyle, building characteristics, environmental exposure, especially dampness-related exposures. This study used the Gradient Boosting Decision Tree(GBDT) algorithm to build the prediction model. The data from CCHH were used to established the prediction model. It was found that there were some differences in the influencing factors between two types of HDMs. The concentration of HDMs were found a significant correlation (p<0. 05)with the number of indoor moisture indicators. 17 influencing factors of HDMs concentrations from four aspects were finally established in this study. The training model of GBDT has a reasonable accuracy(R2>0. 9). This paper provides a reference for predicting the HDMs concentrations in children's bedrooms and the influence of the influencing factors.
Filtration performance of new reduced graphene oxide air filter material against bacteria in the atmosphere during the initial stage of heating
Authors: Xue Kexin , Fan Yuesheng , Zhang Xin , Wang Huan , Gan Weikang , Cui Yong , Li Ming
Published: August 2022

With the large-scale outbreak of the COVID-19, people have gradually realized the importance of bioaerosols in the environment, and how to efficiently filter out microbial aerosols in the air, so as to create a safe and healthy air environment is urgent. The non-bacteriostatic F6 non-woven filter material and the synthesized new reduced graphene oxide air filter were tested and analyzed in this paper, and the filtration performance of the material against bacterial aerosols in the atmosphere at the initial stage of heating. The results showed that during the initial stage of heating, the particle size distributions of aerosols in the atmosphere during working days were stageⅠ(>7.0μm)4.34%, stageⅡ(4.7~7.0μm)4.62%, stageⅢ(3.3~4.7μm)13.30%, stageⅣ(2.1~3.3μm)21.11%, stageⅤ(1.1~2.1μm)38.70%, stageⅥ(0.65~1.1μm)17.92%. The particle size distributions of aerosols in the atmosphere on non-working days were stageⅠ(>7.0μm)4.52%, stageⅡ(4.7~7.0μm)13.66%, stageⅢ(3.3~4.7μm)23.04%, stageⅣ(2.1~3.3μm)31.82%, stageⅤ(1.1~2.1μm)15.18%, stageⅥ (0.65~1.1μm)11.78%. The new reduced graphene oxide filter material had a 10% increase in the filtration efficiency of the total bacterial aerosol compared with the ordinary non-woven filter material. Among them, the filtration efficiency of the respirable bacterial aerosol (particle size <4.7μm) was significantly improved by 40%. The results of this study could provide a certain reference for building a safe interior in the post-epidemic era, and also provided reference value for the research and development of functional air filters.
Release of bacterial aerosols from air conditioning system in office buildings
Authors: Yang Huihui , Li Xian , Qiu Lu
Published: August 2022

Microbial reproduction in air conditioning (AC) systems has caused increasing concern. When subject to airflow, microbes can be separated from substrates and spread into indoor air. This study investigated release of bacterial aerosols from AC systems with different service times in office buildings. Microbial aerosols were collected onto sterilized polycarbonate membranes using an air sampler. The concentration of total bacterial DNA was determined by 16S qPCR targeting universal bacterial genes. The most abundant genus was Lactobacillus before turning on the AC system. After turning on the AC system, the abundant genera were Pseudomonas and Agrobacterium with the service time of three and 12 years. When the AC system was put into use in the early stage, the microbial concentration after turning on the AC system was lower than that before turning on the AC system. However, after a long use of the AC system, the microbial concentration after turning on the AC system (7.50 × 103 copies/m3) was higher than that before turning on the AC system (3.77 × 103 copies/m3). The results show that the service time of AC system influences the community structure and content of indoor bacterial aerosols.
Optimization of the Airflow Organization of the Roof Hood of Electric Furnace under the Influence of Lateral Wind
Authors: Song Gaoju , Chi Jiachun , Li Baoqiang , Geng Changhan , Xu Hongjin , Qiang Tianwei
Published: August 2022

This paper investigates the effect of the “tornado” air distribution in a roof hood under the influence of lateral winds and the ability of this air distribution to resist the influence of lateral winds using numerical simulations. Numerical simulations were conducted to investigate the effect of the “tornado” air distribution on improving the pollutant trapping effect of the roof hood under the influence of lateral winds. The results of the study show that the “tornado” air distribution can effectively improve the capture efficiency of the roof hood under the influence of lateral winds. The results show that the “tornado” airflow can effectively improve the capture efficiency of the rooftop hood under the effect of lateral wind. For the study subject, the ventilation system can achieve energy saving of 74×104kW·h/a and carbon reduction of 720t/a. It provided a reference for the renovation and new construction of roof hoods for large electric furnaces.
Emission Characteristics of Formaldehyde from Natural Gas Combustion and Effects of Hood Exhaust in Chinese Kitchens
Authors: Zheng Zihao , Zhang Hemiao , Qian Hua , Li Jingguang , Liu Cong
Published: August 2022

Formaldehyde (HCHO) is a well known carcinogen. While most studies investigate emission from wood-based materials, knowledge about releasing of HCHO by natural gas combustion is quite limited. This study conducted field measurements in 9 households to address this issue. Formaldehyde generated by natural gas combustion in kitchens can quickly disperse to an adjacent living room when kitchen door is open. A range hood can effectively remove formaldehyde in kitchens if kitchen window is open and kitchen door is closed. Its performance would decrease by half otherwise. These results imply a health co-benefit of reducing household usage of carbon-based natural gas in the age of carbon neutrality aiming climate change.
Research on the Dust Suppression Effect of Three Types of Baffles on the Particle Flow Horizontal Projectile Falling Process in Transverse Airflow
Authors: Sun Hongfa , Li Zeyu , Long Jibo , Li Angui
Published: August 2022

Industrial progress is the source of social development. As one of the important links in the industrial production process, industrial particulate transportation systems such as coal, cement, mineral materials and food transportation cause a large number of dust diffuse problems, which have become the pollution source of the deterioration of the environment quality in the workplace. In the production process, the initial velocity of the conveyor belt makes the particle flow form a horizontal projectile motion, which causes the dust pollution and transverse airflow often further aggravates the dust diffusion. Firstly, the author verified the applicability of Discrete Phase Model by using experimental result. Then, this paper studies the control effect of dust emission in the particles flow horizontal projectile fall process with different types baffle and different baffle positions under transverse airflow. The results show that the semicircular baffle has a better dust suppression effect, followed by the V-shaped baffle, the straight baffle is the worst. The semicircular and V-shaped baffles are moved closer to the particles source out, the better the dust suppression effect. The dust suppression effect of the straight baffle gradually improves as the distance increases, and reaches the best at a distance of L=1 m. The research results provide a theoretical basis for ventilation dust removal design of industrial particulate transport systems.
Extraction, Purification, Quantification, and Stability of Bioactive Spilanthol from Acmella oleracea
Authors: Grymel Mirosława , Mazurkiewicz Roman , Bajkacz Sylwia , Bilik Janusz , Kowalczyk Sławomir
Published: August 2022

Acmella oleracea is an ethnobotanically significant plant with a relatiwely high content of spilanthol. Due to its broad spectrum of activity, including anti-inflammatory,
antioxidant, analgesic, antifungal, and bacteriostatic properties, it is considered a valuable bioactive natural product. In addition, spilanthol as its main bioactive component inhibits
facial muscle contractions, making it an attractive ingredient in anti-wrinkle and anti-aging cosmetics. Due to its muscle paralyzing effects, it is called herbal botox. The commercial
interest in spilanthol encourages the development of effective methods of isolating it from plant material. The methodology used in this paper allows for the obtaining of extracts from
Acmella oleracea with a relatively high content of spilanthol. An effective method of spilanthol extraction from all aerial parts of Acmella oleracea as well as methods of
enriching spilanthol concentration in extracts achieved by removing polar and acidic substances from crude extracts was developed. To quantify the concentration of spilanthol, a simple, fast
and economically feasible quantification protocol that uses nuclear magnetic resonance (HNMR) was developed. In addition, it has been proven, that oxidation of spilanthol by air gives
(2E,7Z)-6,9-endoperoxy-N-(2-methylpropyl)-2,7-decadienamide. The studies on spilanthol solutions stability were carried out and the conditions for the long-time storage
of spilanthol solutions have also been developed. Additionally, for confirmation of obtained results a sensitive (LOQ=1 ng/mL), precise (RSD lower than 7%) and accurate (RE lower than 7.5%),
new HPLC-MS/MS method was applied.