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Numerical study of the influence of the atmospheric pressure on the thermal environment in the passenger cabin

Building Simulation 2024年第2期17卷 253-265页

作者： Xin Su Yu Guo zhengwei long Yi Cao Tianjin Key Lab.of Indoor Air Environmental Quality Control School of Environmental Science and EngineeringTianjin UniversityTianjin300072China Shanghai Aircraft Design and Research Institute Jinke RoadPudong DistrictShanghai201210China

The cabin air pressure remains lower than the horizontal atmospheric pressure when the airplane is in flight.Air pressure is one of the parameters that must be taken into consideration while studying the thermal environment of an airplane cabin.There are still no reference values for aircraft cabins despite the fact that numerous studies on low pressure heat transfer have demonstrated the connection between convective heat transfer coefficient(CHTC)and air pressure.In this paper,a correction method for CHTC under low pressure conditions was established by using the dummy heat dissipation in the low-pressure cabin experiment.On this basis,a thermal environment simulation model was developed,then was applied to the simulation of a seven-row aircraft cabin containing 42 passengers,and the CHTC and heat loss of dummy surface in the cabin were obtained.Finally,the results of PMV calculated by using heat dissipation and air parameters at sampling points were compared.The results show that the modified CHTC can accurately reflect the cabin thermal environment under low pressure conditions,and the correction of CHTC can be realized by adjusting the turbulent Prandtl number,which is nonlinear correlated with the pressure.The simulation results of the thermal environment in the seven-row cabin show that the CHTC changes by about 42%before and after modification.The air pressure decreases during take-off,which reduces the average CHTC of the crew surface from 5.09 W/(m^(2)·K)to 4.56 W/(m^(2)·K),but the air temperature rises by about 0.2°C as a whole.The deviation of PMV results calculated by using simulated heat loss data and using air parameters of measuring points in space is up to 0.5,but the latter is representative for calculating the thermal comfort level of the whole cabin.

关键词： low pressure aircraft cabin simulation heat dissipation convective heat transfer coefficient

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Study of the multi-physics field-coupled model of the two-stage electrostatic precipitator

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Building Simulation 2024年第3期17卷 387-398页

作者： Wenjia Hao Yu Guo Yukun Wang Tao Yu Hao Gao zhengwei long Tianjin Key Laboratory of Indoor Air Environmental Quality Control School of Environmental Science and EngineeringTianjin UniversityWeijin Road 92Tianjin300072China Wuhan Second Ship Design and Research Institute WuhanChin

The two-stage electrostatic precipitator is widely used to purify oil mist particles.However,there is limited research on the influences of relative humidity,particle deposition characteristics,and the generation of gaseous pollutants.Therefore,this paper established a numerical model of the electrostatic oil mist purifier and applied it to a two-stage electrostatic precipitator.Then the model was used to investigate the corona discharge characteristics under different relative humidity conditions in the charged zone,the particle deposition characteristics,the purification efficiency,the ozone concentration distribution,and the oil vapor concentration distribution in the collection zone.The results indicate that,with a constant temperature,the corona current decreases as relative humidity increase,and there is a quadratic relationship between relative humidity and current.The variation in relative humidity has little impact on the purification efficiency.The maximum ozone concentration occurs near the electrode line,and its concentration is influenced by the discharge current and inlet airflow velocity.The oil vapor concentration reaches its maximum value at the side plates,with a value of 19 ppb,while it reaches the minimum value at the collecting zone electrode plate,with a value of 2 ppb.The temperature is the main factor affecting the volatilization of the oil film,with higher temperatures resulting in higher oil vapor.

关键词： two-stage ESPs particle deposition corona discharge oil vapor

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An improved wall-mounted displacement ventilation system in a large-span machining workshop

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Building Simulation 2022年第11期15卷 1943-1953页

作者： Fei Liu Tengfei(Tim)Zhang Liqiang Yang zhengwei long Tianjin Key Laboratory of Indoor Air Environmental Quality Control School of Environmental Science and EngineeringTianjin University92 Weijin RoadTianjin 300072China School of Civil Engineering Dalian University of Technology(DUT)2 Linggong RoadDalian 116024China Tianjin Fengjin Auto Parts Co. Ltd.8 1 Xianfeng East RoadTianjin 300310China

A machining workshop requires ventilation that removes oil mist particles efficiently and conditions air to a comfortable temperature.Displacement ventilation has been reported to be highly efficient in removing airborne pollutants in a workshop.However,the traditional wall-mounted displacement ventilation system may be inadequate for delivering conditioned,clean air to the internal zone of a large-span workshop.This investigation proposed an improved wall-mounted displacement ventilation system in which machining equipment is elevated,relay fans are operated in corridors in the cooling season,and ceiling air exhausts are lowered.The proposed ventilation system was compared with the traditional wall-mounted displacement ventilation system and a displacement ventilation system with multiple local diffusers in the corridors,separately.A validated computational fluid dynamics(CFD)software program was used to investigate the three ventilation systems in both the cooling and heating seasons.The airflow,oil mist particle concentration,and air temperature under the three ventilation systems were evaluated.The results revealed that the traditional wall-mounted displacement ventilation system is inappropriate for use in a large-span workshop,particularly in the cooling season.The proposed improved wall-mounted displacement ventilation provided the lowest oil mist particle concentration in the breathing zone and an appropriate air temperature in the occupied zone in both the cooling and heating seasons.Notably in the cooling season,the proposed system reduced the oil mist particle concentration by 48.5%in the breathing zone as compared with the traditional system.Such an improved ventilation system is highly recommended for use in large-span workshops.

关键词： ventilation workshop oil mist particle temperature CFD

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Simulation study of the purification system for indoor oil mist control in machining factories

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建筑模拟(英文) 2023年第8期16卷 1361-1374页

作者： Yukun Wang Yu Guo Wenjia Hao Wei Liu zhengwei long Tianjin Key Laboratory of Indoor Air Environmental Quality Control School of Environmental Science and EngineeringTianjin UniversityWeijin Road 92Tianjin 300072China Division of Sustainable Buildings Department of Civil and ArchitecturalEngineeringKTH Royal Institute of TechnologyBrinellvägen 23Stockholm10044Sweden

High-concentration oil mists can cause serious health problems to workers,which are generally mitigated by ventilation and purification systems.However,the coupling relationship between these systems is not clear.In this study,the effects of purifier outlet direction,purification air volume,installation height,and purification efficiency on indoor oil mist distribution were investigated by numerical simulation using an actual machining factory.The mitigation of oil mist in various combinations of ventilation and purification systems was also discussed.The results show that the outlet direction of the purifier has a great influence on the distribution of oil mist in the factory,and the maximum difference of oil mist concentration in the breathing zone under different orientations is 17%.The best purifier outlet direction is vertically upward.When the purifier outlet direction is upward,a larger purification air volume is beneficial for contaminant removal,and a lower purifier exhaust installation height is helpful for oil mist discharge from the bottom of the factory and reducing the concentration of oil mist in the breathing area.The oil mist concentration of purifier exhaust increases from 0 to 2 mg/m^(3) and the oil mist concentration in the breathing zone increases by 67%.The combined system of purification system with the roof exhaust system and displacement ventilation system has the optimal pollution removal efficiency and the lowest concentration of oil mist in the breathing zone compared to other systems.The research results can provide a reference for the design,installation,and operation of ventilation and purification systems in machining factories.

关键词： oil particulate matter purification system ventilation system indoor air quality CFD

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Determining V-I characteristics of energy-efficient electrostatic assisted air filtration system by utilizing the back-corona induced current model

Energy and Built Environment

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Energy and Built Environment 2023年第2期4卷 227-235页

作者： Zhuangbo Feng Shi-Jie Cao zhengwei long School of Architecture Southeast University2 SipailouNanjing 210096China Global Center for Clean Air Research(GCARE) Department of Civil and Environmental EngineeringFaculty of Engineering and Physical SciencesUniversity of SurreyGuildfordUnited Kingdom Tianjin Key Lab.of Indoor Air Environmental Quality Control School of Environmental Science and EngineeringTianjin UniversityTianjin 300072China

The widely utilized high efficient particulate air filters(HEPA)and electrostatic precipitator(ESP)respectively has the shortcomings of relatively high energy consumption and low filtration efficiency.In order to overcome the disadvantages of two traditional air filtration system,electrostatic assisted air filtration system(combining HEPA and ESP)has been proven to achieve high filtration efficiency and low energy consumption simultaneously.Predicting of V-I characteristics of electrostatic filtration system with configuration of“pin to filter medium to grounded device”is very essential and challenging due to the back corona phenomenon.This study utilized the back-corona based current model to predict the V-I characteristics of electrostatic system with different filter medium types and“pin-to-filter”distances.Experiments are conducted to provide data for model validation by changing filter types and locations of discharge pin.The results indicated that both of the predicted values of total discharge current and back-corona induced current agreed well with the experimentally measured data.This validated mathematical model could be used for preliminary design of electrostatic assisted filtration system with configuration of“pin to filter to grounded device”.Based on the V-I characteristics predicted by the semi-empirical model,the electrostatic filtration efficiency could be estimated.

关键词： Electrostatic assisted air filtration system Corona discharge Back corona Voltage-current characteristic Energy-efficient

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Decreasing inhaled contaminant dose of a factory worker through a hybrid Emergency Ventilation System:Performance evaluation in worst-case scenario

能源与人工环境(英文)

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能源与人工环境(英文) 2020年第3期1卷 319-326页

作者： Alicia Murga zhengwei long Sung-Jun Yoo Eisaku Sumiyoshi Kazuhide Ito Faculty of Engineering Sciences Kyushu UniversityJapan School of Environmental Science and Engineering Tianjin UniversityChina Technical Research Institute Obayashi CorporationJapan

Air pollution is detrimental to human health,causing several human illnesses.The industrial microenvironment generates high levels of indoor airborne pollutants,becoming a pervasive issue for workers.It is essential to im-prove the indoor air quality in this workplace by applying enhanced ventilation systems to minimize inhalation risk.Displacement ventilation is used in industrial buildings because of its stratified air distribution and low cost.However,in case of accidental pollutant release,an enhancement is needed to minimize inhalation exposure.This study proposes a hybrid emergency ventilation system using localized push-pull ventilation to improve the installed displacement ventilation system of a representative workshop.Computational fluid dynamics was ap-plied to calculate steady-state indoor air flow and volume-averaged pollutant concentration.System performance was evaluated in terms of source position;a computer simulated person was integrated to the building to confirm effectiveness against personal inhalation.Results showed marked improvement in performance when push-pull technique was used:room-averaged concentration diminished up to 91%while ventilation rate only increased 4%.Inhaled pollutant mitigation was achieved but performance dependence against leakage source and personal position was confirmed.

关键词： Computational fluid dynamics Hybrid ventilation Industrial environment Computer simulated person Inhalation exposure

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Experimental study of oil mist characteristics generated from minimum quantity lubrication and flood cooling

能源与人工环境(英文)

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能源与人工环境(英文) 2021年第1期2卷 45-55页

作者： Yiwen Wang Alicia Murga zhengwei long Sung-Jun Yoo Kazuhide Ito Tianjin Key Lab.of Indoor Air Environmental Quality Control School of Environmental Science and EngineeringTianjin UniversityTianjin 300072China Faculty of Engineering Sciences Kyushu UniversityJapan

The use of metalworking fluids during machining can generate oil mist and endanger the health of workers.In order to study the characteristics and emission laws of oil mist generated by machining,this study constructed a test bench to simulate the turning process.Parameters affecting the oil mist generated in the minimum quantity lubrication(MQL)mode and flood cooling mode were studied by means of single-factor experiments,and the formation mechanisms of oil mist were analyzed.The results show that the oil mist generated by the MQL system has two main sources,the initial escape of oil mist into the air and the evaporation/condensation of oil mist.The centrifugation has almost no effect on oil mist formation in the MQL mode.The mass concentration of oil mist generated by the MQL system is proportional to the cutting oil flow rate.When the work-piece is at room temperature,increasing the air supply pressure and nozzle distance,increases the oil mist mass concentration.For the flood cooling mode,the concentration of centrifugal aerosol is linearly and positively correlated with the relative centrifugal force generated by the work-piece,and the coefficient of determination(R 2)is above 0.97.The oil mist mass concentrations in MQL mode is 8.33 mg/m^(3)~305.88 mg/m^(3).The MMD and SMD are 0.74μm to 4.42μm and 0.31μm to 2.14μm,respectively.The oil mist mass concentrations in flood cooling mode is 0.2 mg/m^(3)~22.42 mg/m^(3).The MMD and SMD are 1.81μm to 6.58μm and 0.45μm to 5.13μm,respectively.

关键词： Oil mist Metalworking fluids Minimum quantity lubrication Flood cooling Turning

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Endoplasmic reticulum stress and autophagy in cerebral ischemia/reperfusion injury:PERK as a potential target for intervention

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Neural Regeneration Research 2025年第5期20卷 1455-1466页

作者： Ju Zheng Yixin Li Ting Zhang Yanlin Fu Peiyan long Xiao Gao zhengwei Wang Zhizhong Guan Xiaolan Qi Wei Hong Yan Xiao Key Laboratory of Endemic and Ethnic Diseases Ministry of Education&Key Laboratory of Medical Molecular Biology of Guizhou ProvinceGuizhou Medical UniversityGuiyangGuizhou ProvinceChina Guizhou Center for Disease Control and Prevention GuiyangGuizhou ProvinceChina Department of Histology and Embryology Guizhou Medical UniversityGuiyangGuizhou ProvinceChina Collaborative Innovation Center for Prevention and Control of Endemic and Ethnic Regional Diseases Co-constructed by the Province and Ministry GuiyangGuizhou ProvinceChina

Several studies have shown that activation of unfolded protein response and endoplasmic reticulum(ER)stress plays a crucial role in severe cerebral ischemia/reperfusion injury.Autophagy occurs within hours after cerebral ischemia,but the relationship between ER stress and autophagy remains unclear.In this study,we established experimental models using oxygen-glucose deprivation/reoxygenation in PC12 cells and primary neurons to simulate cerebral ischemia/reperfusion injury.We found that prolongation of oxygen-glucose deprivation activated the ER stress pathway protein kinase-like endoplasmic reticulum kinase(PERK)/eukaryotic translation initiation factor 2 subunit alpha(e IF2α)-activating transcription factor 4(ATF4)-C/EBP homologous protein(CHOP),increased neuronal apoptosis,and induced autophagy.Furthermore,inhibition of ER stress using inhibitors or by si RNA knockdown of the PERK gene significantly attenuated excessive autophagy and neuronal apoptosis,indicating an interaction between autophagy and ER stress and suggesting PERK as an essential target for regulating autophagy.Blocking autophagy with chloroquine exacerbated ER stress-induced apoptosis,indicating that normal levels of autophagy play a protective role in neuronal injury following cerebral ischemia/reperfusion injury.Findings from this study indicate that cerebral ischemia/reperfusion injury can trigger neuronal ER stress and promote autophagy,and suggest that PERK is a possible target for inhibiting excessive autophagy in cerebral ischemia/reperfusion injury.

关键词： apoptosis ATF4 autophagy C/EBP homologous protein cerebral ischemia/reperfusion injury eIF2α endoplasmic reticulum stress PERK

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船舶住舱热环境优化设计分析

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中国舰船研究 2022年第2期17卷 49-56页

作者：柏铁朝许建郑立捷龙正伟操桃秀中国舰船研究设计中心湖北武汉430064 天津大学环境科学与工程学院天津300072

[目的]船舶住舱的热舒适性对船员生活与工作有着重要影响,而采用实验研究和传统的数值模拟试算法进行送风参数设计耗时较长,为此,将基于本征正交分解(POD)的逆向设计方法应用于典型住舱的送风参数设计。[方法]选择船舶典型的住舱结构,... 详细信息

[目的]船舶住舱的热舒适性对船员生活与工作有着重要影响,而采用实验研究和传统的数值模拟试算法进行送风参数设计耗时较长,为此,将基于本征正交分解(POD)的逆向设计方法应用于典型住舱的送风参数设计。[方法]选择船舶典型的住舱结构,采用计算流体力学(CFD)方法建立三维数值模型,在获得流场、温度场以及浓度场结果的基础上,结合基于本征正交分解的逆向设计方法,以九人住舱的热舒适性和呼吸区最低污染物浓度作为优化目标进行逆向设计。[结果]结果表明,基于本征正交分解的逆向设计方法可以对多参数、多目标进行逆向优化,相比传统的试算法,其可节约时间90%以上,大幅提高了船舶住舱送风参数的设计效率。[结论]本征正交分解方法是一种高效的船舶住舱设计方法,通过逆向设计,可以得到合适的送风参数设置范围,能够为船舶住舱送风参数的选择提供参考。

关键词：本征正交分解船舶住舱计算流体力学热舒适性

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复合式静电除尘器滤料表面的电势特性

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高电压技术 2014年第6期40卷 1717-1723页

作者：冯壮波龙正伟天津大学环境科学与工程学院天津300072

为改进复合式经典除尘系统,研究了针尖-极板系统内滤料表面电势分布以及电晕放电过程结束后滤料表面电势消逝规律。首先通过针尖-极板系统使得极板上的滤料荷电,在电晕放电过程结束后,再使用表面电位计测量滤料表面电势分布与衰减规律... 详细信息

为改进复合式经典除尘系统,研究了针尖-极板系统内滤料表面电势分布以及电晕放电过程结束后滤料表面电势消逝规律。首先通过针尖-极板系统使得极板上的滤料荷电,在电晕放电过程结束后,再使用表面电位计测量滤料表面电势分布与衰减规律。测量的干净滤料包括PE（聚酯纤维）、Bag（袋式滤料）;带有颗粒层的脏滤料包括PE（聚酯纤维）。实验结果显示：对于2种干净滤料,其表面初始电势分布比较均匀,偏差〈15%;干净的PE滤料在45 s左右表面电势衰减至稳定值而Bag滤料15 s左右可以达到稳定,Bag滤料表面电势衰减速度快于PE滤料;当阴极电压在10～35 kV间变化时,干净PE滤料初始电势稳定在1 500 V左右而Bag滤料稳定在1 200 V左右,阴极放电电压的增加并不影响滤料表面电势初始值;对于带有颗粒层的PE滤料,颗粒层表面电势低且干净滤料部分电势高。研究结果可供复合式静电除尘系统的设计参考。

关键词：复合静电过滤系统电晕放电滤料表面电势颗粒层反电晕现象

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