bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy consumption baselining and benchmarking of green office buildings in Shanghai
Authors: Yin Ruxin , Pan Yiqun , Ding Zhiliang
Published: August 2022

In recent years, many green buildings were built across China, but the actual performance is not as good as expected. Therefore, it is necessary to improve their performance and establish an objective energy consumption baseline as well as the benchmarking approach for green office buildings in Shanghai. Firstly, we categorized the green office buildings in Shanghai into two type - small and large, according to their floor area. Then we defined the baseline of EUI (energy use intensity, kWh/sq.m.a) based on the survey and submetering data and developed the reference models for both small and large green office building. Secondly, we specified four EUI reference levels for each type after studying the energy saving potential of green office buildings in Shanghai. Thirdly, in order to make the benchmarking approach more objective, we proposed EUI correction method for office buildings considering three main influencing factors - schedule, occupant density and meteorological parameters. We established a typical building model library of office buildings in Shanghai. We adopted regression analysis to obtain the corrections for schedule and occupant density. As for meteorological parameters, by classifying the typical days and calculating their representative EUIs, we determined the correction method.
Applicable design of multi-functional cascade heat pump system for an office building
Authors: Kim Beom-Jun , Cho Hye-Jin , Lee Soo-Jin , Kwon Taek-Don , Jeong Jae-Weon
Published: August 2022

When the cascade heat pump system is applied as a multi-functional system that can be used not only for hot water supply but also for air-conditioning of buildings, the low-stage cycle is responsible for indoor heating and cooling thermal load, and the high-stage cycle is responsible for hot water supply by raising the refrigerant temperature. Unlike the existing cascade heat pump system designed with only one operation mode for hot water supply, the multi-functional cascade heat pump system should be considered with various parameters. This study was proposed a design sequence of the cascade heat pump system for building application, and the energy-saving performance was compared with the existing cascade heat pump system for hot water supply and parallel heat pump system for air-conditioning. The office building was set for the study, and the thermal load of the building was calculated in the TRNSYS program. The systems were calculated using the thermodynamic equation and the model built into EnergyPlus. As a result, the system can be affected by the outdoor air heat source. The energy-saving performance was 25% for the multi-functional cascade heat pump system compared to the simultaneous use of the existing system.
A Study of Energy Utilization and Carbon Emission Audit of a Commercial Mall in Hot Summer/Warm Winter Region in China
Authors: Wang Xin , Li Dekang , Zhao Jinchi , Wang Fei , Zhang Qianru
Published: August 2022

Evaluation on the carbon emissions of large public buildings and carbon reduction measures are very important to help reach carbon peak demand and carbon neutral. The purpose of this study is to conduct energy audits and energy-saving assessments on large public and commercial buildings to find out the impact of various behavioural activities related to buildings on carbon emissions and energy consumption, and to explore the carbon reduction potential of buildings. In China, the energy structure based on fossil fuels will not change in a short term, and energy consumption will inevitably increase with economic development; however, the energy efficiency is the main factor that affects the building carbon emissions. And changing energy efficiency will reduce emissions by 9.29%, while improving the energy structure will reduce emissions by only 0.46%; it is the key work to slow down greenhouse gas emissions in buildings that is reducing power consumption of electrical equipment, especially the air-conditioning system, which can result in 49.72% energy saving after reforming.
Study on window-opening habit of urban residential buildings in Liaoning province
Authors: Song Jiasen , Feng Guohui , Huang Kailiang , Sun Wen , Zhang Yixian
Published: August 2022

Residents' window-opening behavior is the most basic method to obtain fresh air and improve the indoor environment, and is also an important factor affecting building energy consumption. The behavior of opening and closing windows of urban residents will be different due to regional differences. However, there are less of the thorough enough research on the time and seasonal habit of residents’ window-opening behavior in Liaoning. This paper investigated the window-opening behavior and its influencing factors of 28 typical urban households in natural ventilation and mechanical ventilation houses in Liaoning province by questionnaire survey and on-site testing. The opening and closing behavior of residents’ windows were continuously monitored online for one year by using magnetic sensors of XIAOMI brand. The long-term monitoring results showed that the window-opening behavior of residents in Liaoning has strong seasonality. In summer, the window-opening time is relatively longer, and often more than 24 hours. What’s more, most local residents have the habit of opening windows for ventilation when they get up in the morning, even in the cold winter. The understanding of the window-opening behavior of residents in this area can provide strong support for architectural design or renovation strategy.
Numerical Research on the Performance of a Phase Change Heat Storage Electric Heating Module
Authors: Niu Dongyin , Zhang Tiantian , Tan Yufei , Zhang Wensheng
Published: August 2022

A kind of phase change heat storage electric heating modules filled with the composite PCM was designed and fabricated in this paper. The thermal performance of the module was studied through the experiments, and the thermal performance influencing factors were studied using the FLUENT software. Simulation results indicated that the optimal thermal conductivity of the PCM should be between 3 W/(m·K) and 5W/(m·K). With the designed arrangement of the heating wire, the optimal electric heating power should be between 9.00W/m and 9.85W/m, and the corresponding adjustments should be made according to the local electricity price policy. When the electric heating power is 9.85W/m and the thermal conductivity is 4W/(m·K), the distance between the heating wire should be between 40mm and 45mm, which can ensure the high heat-storage efficiency and heating continuity. In general, the internal temperature of the module is relatively uniform and can maintain stable heat dissipation within the effective heating range for a long time. The temperature fluctuation of the module heat dissipating surface is small. The module has good thermal performance and can meet the heating requirements when being applied to electric radiant heating in the building.
Numerical simulation study on heat transfer characteristics and parameter optimization of solar phase change energy storage fresh air preheating system
Authors: Xu Jintian , Huang Kailiang , Feng Guohui , Lv Xue , Zhang Dongxu
Published: August 2022

In cold regions, indoor fresh air preheating in winter has received much attention. An improved fresh air preheating system using solar energy and phase change energy storage technology is proposed in this study to solve the problem of insufficient fresh air supply in cold regions. This study establishes two-dimensional mathematical model for air-type phase change energy storage device, and compares the error between them and the experimental results. The results show that the comparison between the simulated and experimentally measured is in good agreement. This study explores the effects of velocity of hot air, temperature of fresh air and temperature of hot air during simultaneous heat storage and discharge conditions by using numerical simulation method. The results show that the designed system has the ability to preheat fresh air at 4.5 °C for more than 4 hours under the condition of outdoor average temperature of -10 °C at night, and has practical promotion value. All three parameters affect the thermal performance of the system. When the hot air velocity increases from 1.5 m / s to 2.25 m / s, the liquid fraction increases by 5.16 %, 10.11 % and 14.52 % respectively. Different fresh air temperatures determine the heat storage capacity of the system under the condition of simultaneous heat storage and heat release.
Experimental study on the robustness of ventilation systems in the control of walking-induced disturbances under different walking modes and temperatures
Authors: Ren Jianlin , He Junjie , Kong Xiangfei
Published: August 2022

Ventilation system’s effectiveness can be affected by walking-induced disturbances. A series of experiments were performed in a chamber in this study (6.0 m × 5.9 m × 2.5 m) to measure the walking-induced temperature/flow/pollution field fluctuation characteristics. A method for quantifying the robustness of a ventilation system in the control of walking-induced fluctuations was used in this study. The experimental results showed that the cumulative particle exposure levels under walking modes W1, W2 and W3 were 2.04 ± 0.27, 1.72 ± 0.26 and 0.87 ± 0.12 times the exposure levels without human walking. The four ventilation systems all performed well in indoor temperature disturbance control; however, different walking modes and ventilation systems would result in different walking-induced disturbances of the flow and pollutant fields. For the flow field, the highest range scale robustness value was achieved by the side supply and side return (SS) system. For the pollutant field, the range scale robustness value of the SS system was still the highest, 18.7% larger than the lowest value. With the increase in temperature from 18 °C to 28 °C , the range and time scale robustness of the different ventilation systems decreased by 7.7–18.4% and 1.3–15.7%, respectively.
Exploring the optimal return air height of different air supply modes based on energy consumption analysis and TOPSIS evaluation method
Authors: Ren Jianlin , Duan Shasha , Kong Xiangfei
Published: August 2022

The side return air is considered to be a ventilation form that can effectively remove indoor particulate matter, and relevant scholars have little research on the height of air return outlet for different air supply methods. In this paper, a single-person ward experimental cabin is established, and the focus is to study the effect of different side return air outlet heights on the particle removal effect under three air supply forms. And use CFD simulation to increase the type of return air outlet height, finally use the technique for order of preference by similarity to ideal solution (TOPSIS) method to comprehensively evaluate the pros and cons of 60 working conditions. The results show that the optimal return air height of top air supply and underfloor air supply is 1.2m, and the best working condition of side air supply is 1.6m air supply-0.7m air return of 12ACH. Most of the working conditions of side air supply are better, followed by top air supply, and finally underfloor air supply.
Study on the thermal performance under the implement of multi-vent module-based adaptive ventilation
Authors: Zhang Weijia , Zhang Weirong , Zhang Haotian
Published: August 2022

Indoor occupants' distribution scenarios are in a dynamic change randomly. Moreover, in many occasions with fixed seats, people in areas where cold air blows directly have a poor thermal experience. Therefore, to meet the differentiated environmental demands, novel ventilation strategies to satisfy the changing environmental requirements needs to be explored. In this study, a multi-vent module-based adaptive ventilation (MAV) system with a multi-vent dynamic ventilation module as a core is proposed to increase the adjustability of air distribution and better adapt to variable demands. MAV has three control characteristics of zoning division, completion of the inlets and outlets conversion, and the use of dynamic airflow adjustment. Simulations are conducted based on a typical multifunctional classroom with four common scenarios. The performance of MAV and MV under different scenarios is compared by considering airflow pattern, SVE4, PMV and DR. The results reveal: this ventilation module can effectively realize the zoning division control. MAV can create a more comfortable thermal environment when compared with MV. Various vents schemes realized by the function of the reversing device create different airflow patterns and thermal environments, which can be matched to diverse indoor scenarios. When the indoor scenario changes, the local uncomfortable state can be improved by switching the device to change the vents schemes. In order to deeply adjust thermal discomfort caused by the airflow pattern of downwards under the multi-vents air supply, it is reasonable to introduce dynamic airflow in MAV to improve the draught comfort. This ventilation strategy might be expected as a promising air terminal system that provide flexibility and adaptability for real applications.
Research on air-water coordinated operation of water side free cooling system based on improved particle swarm optimization algorithm
Authors: Ma Keyan , Lv Jie , Zhang Jili
Published: August 2022

Water side free cooling is an important technology for cooling water system to use natural cooling source for energy saving, especially in the field of data center and industrial production. However, the operation regulation of water side free cooling system was lack of scientific basis. This process involves the two-phase circulation of air and cooling water, which requires the coordinated operation of air and water to further optimize the energy consumption. The coordinated operation of air and water includes the coordination of air and water flow in each cooling tower and the matching of the operating numbers of equipment in the system. Firstly, based on the characteristics of the cooling tower, the key equipment in the water side free cooling system, the air-water two-phase heat transfer model in the cooling tower was established. Then, according to the heat transfer model and power model of each equipment in the system, the optimization objectives and constraints are established. An improved particle swarm optimization (PSO) algorithm was proposed to solve the problem of wind water collaborative optimization of water side free cooling system. Finally, this paper takes a small data center cooling water system as an example to analyze the optimization performance of the improved particle swarm optimization algorithm. The simulation results showed that the excellent rate obtained by the improved algorithm can be increased by 36.9%, which is more energy-saving. This method can provide a reference for the energy-saving optimization of water side free cooling system.
Occupant seating optimization to reduce lighting energy consumption and improve comfort
Authors: Lian Linwen , Xie Hui , Song Yuanyuan
Published: August 2022

occupant presence and behavior are non-negligible factors affecting building energy consumption. It should be emphasized: guaranteed building core functions is a prerequisite for energy saving. This paper proposes a method that can minimize building energy consumption and improve occupant comfort. Through monitoring the entry and exit of a 24-person office, occupant presence is obtained. And the difference in comfort of occupants is investigated and analyzed. The occupant is moved to a seat that is more thermally comfortable. Then occupants with a high degree of overlap in-room time are gathered in the same lighting area to reduce lighting energy consumption. Through the multi-objective optimization model, the lighting energy consumption is reduced by 16.2%, and the overall indoor comfort is slightly improved.
Study on thermal performance of phase change materials in photovoltaic system
Authors: Yang Chen , Tao Qiuhua , Zheng Jianwen
Published: August 2022

The thermal performance of solar cells plays an important role in the energy use of solar photovoltaic power generation. The surface temperature of solar cells is a key factor affecting the power generation efficiency. The use of phase change materials in solar cells can increase the thermal storage capacity and weaken the temperature fluctuation under the action of solar radiation, achieving the purpose of improving the system power generation performance. The aim of this paper is to investigate the phase change materials and their thermal performance for solar cell modules through simulations and experiments. In the experimental study, six types of binary composite phase change materials were prepared by selecting two of lauric acid, stearic acid, palmitic acid and tetradecanol in a 1:1 ratio. In the thermal performance tests of the phase change materials, the phase change temperature and latent heat of phase change were measured by the thermogravimetric method using a TGA/DSC simultaneous thermal analyser, and the thermal conductivity was measured by the probe method using a thermal conductivity meter. In the simulation study, a numerical model of the phase change heat transfer is developed, coupling the phase change material to the cell components and performing heat transfer analysis. The results are helpful to the selection of phase change materials that are beneficial for reducing the temperature of solar photovoltaic panels and to explore the effect of radiation levels on the materials.
Experimental study on a modular thermo-activated building system for improving indoor thermal environment and energy saving
Authors: Chen Sarula , Chang Tianxin , Yang Yang
Published: August 2022

Thermo-activated Building Systems is an energy-efficient envelope insulation technology. In this paper, the Modular Thermo-activated Building Systems (MTABS) is proposed to enable flexible installation and maintenance of embedded pipe. Two scaled-down experimental rooms of the same size were built, in which the normal energy-saving wall (NW) and the MTABS wall were applied to the south-facing wall respectively. The MTABS for impacting on the indoor thermal environment and energy saving were measured in continuous low-grade heat injection mode under winter outdoor conditions in Hefei, and were analyzed in comparison with the NW. Experimental results show that MTABS can effectively improve the indoor thermal environment. The average temperature difference between indoor and outdoor of MTABS is 6.72 °C higher than that of NW; when the heat source temperature is 25 °C, the cumulative daily heat fluxes of MTABS is 44.0 kWh·m-2, which providing auxiliary indoor heating while significantly reduces energy consumption.
Fire safety of ventilation systems and fire incidence reports in Norwegian schools
Authors: Yang Aileen , Aamodt Andreas , Samuelsen Per Henning , Garberg Olsø Brynhild , Haukø Anne-Marit , Meraner Christoph
Published: August 2022

School fires are causes of concern in many countries. Although most of these fires are minor in terms of heat release rate, the amount of smoke produced can be substantial and cause significant damage beyond the room of origin. Currently, Norwegian schools have a wide spread of different ventilation strategies and systems, and building owners struggle with how to test, maintain and keep them fire safe. A systematic survey of fire incidences and ventilation strategies in schools for three municipalities in Norway was done to gain better insights into fire safety in schools. The results indicated that the place of origin is often in locker rooms/toilets, kitchen, or outdoors, and the fires were usually deliberately set. For non-arson fires, electrical failure was the most common cause. The majority of the fire incidences were small but would often result in smoke damage and spread of soot in the building, leading to high restoration costs for the local municipality. A lack of documentation of the fire safety and the function of the ventilation system was also identified, indicating a need for improved routines and systems for registering fire incidences and documentation of the technical systems.
Investigation on energy consumption characteristics in different time scales of a metro station
Authors: Guan Bowen , Wang Xinke , Liu Xiaohua , Zhang Tao
Published: August 2022

As a big energy consumer in metro station, the air-conditioning system is responsible for air-cooling and ventilation in cooling season while only for ventilation in other seasons. Understanding the hourly energy consumption characteristics of the system contributes to renewable energy integration and achieving carbon emission reduction in metro stations. Thus, energy consumption characteristics in different time scales of a Beijing metro station is investigated in this study. The results reveal that the air-conditioning system accounts for 61.7% of the total electricity consumption for the entire year, while the proportion rises to 73.7% for the cooling season. In the daily scale, the electricity consumption for air-conditioning increases with the outdoor air temperature rising, while it is nearly free from the effect of the passenger flow rate changing. In the hourly scale, the electricity consumption for air-conditioning shows a weather-condition-related characteristic, the electricity consumption for lighting shows a time-related characteristic, while the electricity consumption for others is nearly constant during the operation period. It is anticipated that the study helps to understand the hourly energy consumption characteristics and provides reference for energy-saving strategy selection in metro stations.
Multi-point access to urban underground road longitudinal ventilation system operation control method
Authors: Liu Chang , Chen Chao , Zhao Rui , Li Qiong , Wang Ping , Shen Zheng
Published: August 2022

While the multi-point access to urban underground roads solve traffic congestion, the pollutants (CO, NOx, etc.) emitted during tunnel travel also pose environmental and health risks to the tunnel drivers and passengers as well as the residents near the tunnel openings. To this end, this study focuses on the environmental safety of urban underground roads with multiple points of entry and exit as the focus of research, based on the law of conservation of mass, fluid dynamics and ventilation engineering theory and simulation of experimental research methods, combined with motor traffic and pollutant (CO, NOx, etc.) emission characteristics, proposed NO concentration prediction model, combined with the urban underground road air flow and ventilation system operating characteristics, the longitudinal distribution law of pollutant concentration along the tunnel is calculated through case analysis, the intelligent control strategy of the ventilation system is proposed. The results show that when the traffic flow reaches 2000veh·h-1, two fans need to be started, and the power consumption is 50% less than that of the whole fan. It is expected to provide a reference basis for the design and efficient low-carbon operation of ventilation system design for urban underground roads with complex structures.
The feasibility of jet fan-assisted ventilation for temperature control of heating belts on a downward-facing sphere in a scientific facility
Authors: Li Yiqun , Tang Wenhao , Wu Chao , Xue Yu , Ye Wei , Zhang Xu
Published: August 2022

To avoid the deformation of the large-scale scientific facility for neutrinos detection due to temperature changes, the heat generated during the top-down annealing of the inorganic glass panels needs to be released in time to maintain temperature control of 21±1°C in the built-up area. Due to the unique shape and the changing heating sources, a novel ventilation strategy that combines jet fans with general ventilation was proposed to satisfy the special environmental control requirement. A small-scale field experiment was conducted to obtain the CFD methods for simulation. Then, the feasibility of the jet fan-assisted ventilation system was discussed in terms of two thermal control zones based on the distance from the heat source. Besides, the effectiveness of the proposed ventilation design was compared with traditional general ventilation with air-conditioned air supplied from the hall ceiling and directly opposite the heating belt based on the temperature and velocity distribution. The results show that: the area outside the thermal control range under jet fan-induced ventilation was reduced by around 60%, and the maximum temperature fluctuated over time within 0.33°C. These results provide a preliminary insight into the use of jet fan-assisted ductless ventilation to achieve precision local temperature control in a large space.
Study on oxygen concentration distribution of Sejila mount tunnel construction based on fluent
Authors: Feng Guohui , Liu Yuhan , Sun Jialin , Zang Yan
Published: August 2022

Sichuan-Tibet Railway is a major construction project to ensure national defense security and support social and economic development in the west. Due to the geographical environment at high altitudes in the Sichuan-Tibet region, for every 1000 m increase in the average altitude, the atmospheric pressure decreases by about 11.55 %, and the oxygen partial pressure decreases accordingly, forming a low-pressure and low-oxygen environment, which affects the construction safety. The oxygen consumption of mechanical equipment in the tunnel and the discharge of pollutants make the construction personnel’s hypoxia problem more serious. Based on the project of the Sejila Mountain Tunnel, this paper divides the tunnel into the working face and the construction section along the tunnel according to different construction procedures. Based on the numerical simulation by CFD software, the distribution law of oxygen concentration in the tunnel construction process before the implementation of the environmental control scheme under different factors is proposed, and the relationship between various influencing factors and oxygen concentration distribution is obtained. It is concluded that oxygen consumption and emission of internal combustion engines and tunnel excavation length are important factors affecting oxygen concentration in the tunnel construction environment.
Experimental study on the temperature distribution in a cross-type interchange subway station fire scenario
Authors: Li Jiaxin , Li Yanfeng , Duanmu Xiangling , Li Lei
Published: August 2022

In order to investigate the temperature distribution beneath the subway ceiling, a series of experiments were carried out in a 1:20 small-scale model of a three-level cross-type interchange subway station. The experimental model contains three floors, including two lines of the metro. The experiment results show that the maximum temperature below the ceiling in the cross-type interchange subway station is slightly higher than the maximum temperature below the ceiling under the unconstrained space burning, because the complex structure of the transfer station affects the flow of the fire-induced smoke. The maximum temperature model proposed by Alpert was modified by analysing the experiment results of the highest temperature below the ceiling in the small-scale cross-type interchange subway station, and the new prediction formula for the maximum temperature excess was proposed. When the distance between fire location and side wall is 1.5 times the tunnel height, the modified coefficient of maximum temperature excess is 1.1348 based on the model proposed by Alpert. This study on this issue may benefit the current design of fire protection measures for the platform ceiling.
Reduced-scale experimental and numerical investigation on the energy and smoke control performance of natural ventilation systems in a high-rise atrium
Authors: Sha Haohan , Zhang Xin , Liang Xiguan , Qi Dahai
Published: August 2022

Natural ventilation (NV) is an effective energy-saving strategy to remove the excessive heat in high-rise atria. The traditional NV system in high-rise atria has inlet openings at the bottom and outlet openings at the top. However, this traditional system may bring fire safety concerns due to the rapid spread of smoke during an atrium fire. To remove the fire safety concern, a new NV system was proposed in this study. This new system applies a segmentation slab to divide the high-rise atrium into upper and lower parts, which can limit the smoke movement. A ventilation shaft is installed to maintain the NV rate and extract smoke. To investigate the energy and smoke control performance of the new and traditional NV systems, a 1:20 small-scale experimental model and CFD numerical model were built. The results indicate that the new NV system with the shaft and segmentation can remove more heat than the traditional NV system. Furthermore, the new NV system can simplify the mechanical smoke exhaust system and improve the smoke control performance, e.g., requires a lower volumetric flow rate and maintains a thinner smoke layer.
Review Of Fire And Smoke Control With Ventilation Systems In Tunnels
Authors: Yao Huangcheng , Yang Bin , Yang Pengfei , Pan Bing’an
Published: August 2022

Underground spaces were paid more attention in the 21st century. As a special underground space, the development of tunnels was even faster. The damage in tunnel, caused by fire and other hazards, is worse than that in spaces above ground due to construction characteristics of underground spaces. Hot smoke cannot be exhausted in time when a fire occurs in tunnel. Therefore, space temperature rises quickly and flashover occurs. Meanwhile, smoke will be accumulated because of poor ventilation. Incomplete combustion, and production of harmful gases such as CO were caused. This review regarding modelling and design methods, based on the characteristics of tunnel fires, summarizes earlier findings and proposes further study plans.
Research on hydrogen leakage and dispersion characteristics in indoor thermal stratification environment
Authors: Shu Zhiyong , Liang Wenqing , Zheng Xiaohong , Qian Hua
Published: August 2022

The leakage of hydrogen in a room is a key issue of hydrogen safety, and ventilation plays an important role in hydrogen dispersion. The hydrogen leakage usually builds a thermal stratification environment due to the low temperature of liquid hydrogen or throttling effect. This study attempts to develop a fast-computational theoretical model of hydrogen dispersion motion in an indoor thermal stratification environment based on the classical buoyant jet model and to carry out an experimental to verify model. The research results show that the developed theoretical model can well predict the trajectory of slowly releasing hydrogen leakage. The motion trajectory of the hydrogen leak oscillates in the thermally stratified environment at a certain height, called as the “lock height”. The smaller the leak port in the uniform environment the larger the horizontal diffusion distance, and the smaller the leak port in the thermally stratified environment the higher the locking height. The research results are expected to predict the hydrogen leakage safety prediction problem and the formulation of related standards and help make ventilation strategies to ensure the hydrogen safety.
Analysis of dynamic characteristics of CO2 concentration in subway cars
Authors: Yang Huagan , Wang Haiying , Wu Yan
Published: August 2022

The air environment in the subway car has a great impact on the comfort and health of passengers. In order to know the real air quality in the car when the train is running, this paper takes CO2 as an indicator and conducts a field test on Line 11 of Shanghai Metro to study and analyse the dynamic CO2 concentration and the fresh air rate in the subway car. The results show that the CO2 concentration increases from the head car to the tail car, and the fresh air volume decreases from the head car to the tail car is the reason for the large difference of CO2 concentration in different cars. The CO2 concentration in the car is greatly affected by the passenger load, and the maximum value of CO2 concentration in the morning peak can reach 2.3 times that of the normal hours. The background CO2 concentration has a certain influence on the CO2 concentration in the car, and the CO2 concentration in the underground line is higher than that in the elevated line in the same carriage. The CO2 concentration in subway cars of the underground line in the morning peak is significantly higher than 1500 ppm, which indicates that the dilution effects of the ventilation can’t meet the fresh air requirements in the morning peak. The research in this paper can provide a reference for the design of the ventilation system of subway trains and the environmental control in the car.
Study of Natural Ventilation Potential and Performance for the Undergroun Utility Corridor Using Numerical Method
Authors: Zhao Xiaoyu , Wu Yan
Published: August 2022

The utilization of urban underground space is a strategic choice to solve land space shortage, traffic congestion and environmental pollution. The underground corridor serves as both commercial and entertainment spaces. Proper natural ventilation system is believed to combine the advantages of good indoor air environment and high energy efficiency. In the present study, field experiments and numerical simulation are performed to compare the natural ventilation performance in the underground utility corridor under different layout of gates and skylights during the transitional season. The results show that the overall Richardson number is calculated to analyze the dominant driving force of the corridor. Second, it has been found that the arrangement of skylights and asymmetric gates can well promote natural ventilation in the corridor. The air exchange rate of the corridor with asymmetrical outlet is 10% higher than that with symmetrical outlet under the conditions in this study. Third, the wind speed at the openings in the middle of the corridor is higher than that of other openings in the corridor with skylights.
Study on influence of breathing zone combined with underfloor makeup air supplement on smoke exhaust of road tunnel fire
Authors: Lei Wenjun , Qi Yue , Zhang Xinyu , Tai Chuanmin , Zhang Linhua , Sun Guohong
Published: August 2022

In the era of rapid economic development, tunnel construction projects are increasing year by year in China, continuously expanding the urban network In the era of rapid economic development, tunnel construction projects are increasing year by year in China, continuously expanding the urban network radiation area, and accelerating the progress of the national modernization project. The subsequent tunnel traffic fire accidents are also increasing When a tunnel fire occurs, how to effectively supply makeup air to prevent the fire smoke from spreading to the evacuation passage of the When a tunnel fire occurs, how to effectively supply makeup air to prevent the fire smoke from spreading to the evacuation passage of the tunnel and exhaust the smoke as soon as possible has become a key concern in the field of tunnel disaster prevention. The layout of the smoke exhaust outlets under the mode of breathing zone combined with underfloor makeup air supplement was mainly used to study the problem of smoke exhaust in tunnel fires. The results show that under the same smoke exhaust flow rate, with the increase in the area of the results show that under the same smoke exhaust flow rate, with the increase in the area of the smoke outlet, the smoke exhaust efficiency of each exhaust outlet increases, and the total efficiency also increases. The width of the exhaust outlet has a significant effect on the smoke exhaust efficiency. However, the length of the exhaust vent has little effect on the efficiency of smoke exhaust. Under the mode of breathing zone combined with underfloor makeup air supplement, arranging smoke outlet with a size of 2 m×1.5 m every 10 m has a better smoke extraction effect, and the total smoke exhaust efficiency can reach 75.77%. Fire safety of road tunnels has always been the focus of social concern. The makeup air supplement and smoke exhaust mode proposed in this study is expected the makeup air supplement and smoke exhaust mode proposed in this study is expected to provide a theoretical basis for the design of tunnel smoke prevention and exhaust systems.
Construction and research on the navigation condition of oil supply vessels
Authors: Hong Shiding , Qin Chaokui , Dai Haifeng , Lai Xin
Published: August 2022

Constructing navigation condition of oil supply vessels is of vital importance to both the research on the main engine and the safety of navigation. This paper carries out in-depth research and analysis based on the half-year shipping data derived from Hai Gong You 31, the oil supply vessel of Shanghai Chimbusco Marine Bunker Co., Ltd. After classifying 3946 pieces of shipping data, and there are 119 valid sequences. As for 13 characteristic parameters ,which include time, distance, average acceleration ,etc., they are eigenvalues of kinematics sequences ,and there are principal component analysis and contribution rate analysis relevant to them. Instead of original eigenvalues, three principal components whose contribution ratios are the highest and the accumulative one is around 85% are selected to be analyzed then. By means of between-groups linkage, this paper calculates the distance among clusters ,and the nearest two clusters are regarded as a new cluster. Afterward, calculations and combinations are made over and over till there is only one cluster. Eventually, the navigation condition of oil supply vessels is successfully formed, that is the one with a total length of 9240s.
Analysis on air volume balance and resistance characteristics of central exhaust system in tunnel
Authors: Gan Lu , Wang Hao
Published: August 2022

With the increase of tunnel length, the air volume imbalance among the outlets for the central exhaust system is serious. Which causes the actual air volume of the end outlet is small. Combined with the design of an urban road tunnel, even air distributor (EAD) groups are installed in the exhaust duct. For different EAD groups setting, the air volume imbalance among the outlets and the resistance characteristics of exhaust system are analyzed. The results show that EAD groups improve the air exhaust uniformity significantly, which is less affected by the exhaust air volume. Furthermore, the flow impedance of the exhaust duct presents a two-stage increase distribution corresponding to the augment of exhaust air rate for a given duct width. For the central exhaust system equipped with EAD groups, closing the 1#-3# outlets can further reduce the CO concentration in the middle section of tunnel.
Study on the Influence of the Slope Composition of the V-shaped Tunnel on the Smoke Exhaust Efficiency of the Point Exhaust System
Authors: Xie Fei , Li Junmei , Liu Wenbo , Dong Qiwei , Hu Cheng , Qi Zhao
Published: August 2022

The influences of the slope composition on both sides of the variable slope point and the opening numbers of the exhaust vent on the smoke diffusion and the smoke and heat exhaust efficiency in V-shaped tunnel were investigated by the numerical method. The results showed that for the asymmetric V-shaped tunnel, increasing the number of exhaust vents on the large slope side can improve the smoke and heat exhaust efficiency, but control the smoke in a smaller rang is relatively difficult. The corresponding smoke exhaust vent opening strategy should be drawn up in accordance with the composition of the slope of the V-shaped tunnel and the goal of the smoke control system in practice.
The impact of jet fans layout on the CO concentration distribution inside tunnel for the congestion scenario
Authors: Xu Lin , Chen Jiale , Yu Kongfei , Liu Jie , Qiu Mingxuan
Published: August 2022

Air pollution inside tunnel has attracting more people’s attention in China. The occurrence of traffic accident in the rush hours would cause widespread traffic congestion inside tunnel. This may further lead to accumulation of air pollutants near the accident location. To analyze the accumulative effect, the air velocity and CO concentration under different jet fans layout are predicted by use of the multi-segments model. The results show that the occurrence of the accident does influence the spatial-temporal distributions of air velocity and CO concentration. After the accident, air velocity in the congestion region drops significantly and CO concentration jumps downstream the accident location. For a traffic accident-induced congestion scenario, increasing the jet fans in the upstream area is more effective to dilute the air pollutants inside tunnel.
Human re-inhalation ratio under typical conditions
Authors: Zong Jie , Ai Zhengtao
Published: August 2022

Inhaled air quality is directly related to occupants’ health and quality of life. In this study, a numerical breathing thermal manikin was employed, who breathed following a sinusoidal function, with 10 breathing cycles per minute. Each cycle was composed of three phases: 2.5 s inhalation, 2.5 s exhalation, and 1 s pause. The influence of pulmonary ventilation rate, breathing mode and breathing cycle period on the re-inhalation ratio were studied by computational fluid dynamics (CFD) technology in combination with the species transport model. It was found that increasing the pulmonary ventilation rate led to a lower re-inhalation ratio. The re-inhalation ratio is the largest with the value of 0.91%, when exhaled through the mouth and inhaled through the nose. The re-inhalation ratio was up to 23.9 % lower with a pause of 1 s in the breathing cycle than without pause. When the pulmonary ventilation rate increased from 6 L/min to 8 L/min, the re-inhalation ratio decreased from 0.91% to 0.71%. This information would be an important basis for the development of the human microenvironment control and technologies, including intelligent, personalized air supply devices, local air supply and exhaust methods, and other advanced ventilation and airflow technologies.
A preliminary experimental study on the user behaviors and aerosol emissions of electric toothbrushes
Authors: Tang Wenhao , Li Yiqun , Ye Wei
Published: August 2022

The oral cavity is a human organ where a high concentration of microorganisms occupies. Evidence has shown that using dental instruments may trigger the release of microbial aerosol indoors. In this paper, the aerosol emissions during the working process of electric toothbrushes were investigated as follows. First, brushing habits, e.g., the favorite brand and flavor of the toothpaste, first tooth/teeth to brush, etc., were determined by 70 questionnaires from university students. Second, typical toothpaste usage per time was determined as 0.3g–0.5g based on a squeezing test by the group. Third, an experimental setup was designed to simulate toothbrushing to measure aerosol emissions. Finally, the measured emissions during toothbrushing were compared with other oral activities. The results showed that the peak PM2.5 emission rate can reach up to 5.9 μg/s by using a typical toothpaste dosage. The number of particles emitted if the incisors were brushed first can be 1–2 times higher than if the molars were firstly brushed. The magnitude of aerosol generated from electric toothbrushing was similar to that of coughing and sneezing.
Research on the calculation method of dressing thermal resistance based on infrared thermal imaging technology
Authors: Liu Guodan , Jiang Shan , Ji Yihang , Zhang Yao , Wang Gang , Liang Shimin , Liang Shuwei
Published: August 2022

With the popularity of intelligent technology, it has become an important trend to control the air conditioning terminal equipment intelligently to build the comfortable indoor environment. Therefore, it is necessary to automatically collect environmental and individual parameters (metabolic rate and clothing thermal resistance) and calculate PMV to predict human thermal sensation in real time. In this process,environmental parameters can be automatically measured and uploaded by the device. The metabolic rate is related to human level of activity . However,clothing thermal resistance is affected by many factors such as environment and level of activity.Taking the clothing thermal resistance as a fixed value according to thermal comfort standards will lead to deviations in thermal sensation prediction. In addition, many Chinese dresses cannot be found corresponding thermal resistance value in the thermal standard. In view of this,this paper studies two algorithms to obtain clothing surface temperature and calculate clothing thermal resistance by taking thermal image of the dressed human body with the infrared thermal imager,and compare them with the method of finding the clothing thermal resistance database in thermal comfort standard.And then,we calculate the PMV(predicted mean vote) using clothing thermal resistance obtained by three methods.The results of PMV and the questionnaire(ASV) are compared to analyze the feasibility of these methods. The results show that the mean deviation between the PMV calculated by one algorithm and the ASV is 0.33 scale when sitting in single-layered dress in summer,and that is 0.45 scale when sitting in multi-layered dress in winter. The results of PMV is significantly correlated with ASV. All of these prove that clothing thermal resistance can be calculated by this non-contact method, and it can be benefit to obtain indoor human thermal sensation and adjust and control thermal environment intelligently.
Field Study of thermal comfort of indoor fitness places in cold region
Authors: Jia Chenyang , Zhao Shengkai , Gao Siru , Tong yuanyuan , Zhai Yongchao
Published: August 2022

A healthy body is the foundation of everything. The indoor environment comfort of fitness places has been paid more and more attention. However, there is a lack of relevant standards for the thermal environment of indoor sports and fitness venues in China, especially the research on the indoor thermal environment in different seasons. Therefore, in our study, physical environment parameters such as indoor temperature and humidity, black ball temperature, air flow rate and CO2 concentration in 9 indoor fitness places in Xi ‘an in different seasons were measured on site. At the same time, a subjective questionnaire survey was conducted on thermal sensation and acceptability of the people who were exercising in the fitness places. Through subjective questionnaire analysis, respondents generally have a high degree of satisfaction and acceptance of temperature, and the average thermal comfort vote is the highest when the indoor temperature is 17.9-23.9°C. In addition, the thermal comfort of different sports in the same space also has certain differences. The fitness people indoor have lower satisfaction with air flow and air quality. Based on the study of the factors affecting indoor thermal comfort, this paper puts forward the improvement strategies for improving indoor thermal comfort, and provides scientific basis for the design and operation of fitness venues.