Identification of Model Parameters of Vaporized Hydrogen Peroxide Decomposi-tion Flux on Building Materials for Compu-tational Fluid Dynamics

To maintain healthy and sanitary indoor air quality, development of effective decontamination measures for the indoor environment is important and hydrogen peroxide is often used as decontamination agent in healthcare environment. In this study, we focused on the decomposition phenomena of vaporized hydrogen peroxide on wall surfaces in indoor environment and discussed a wall surface decomposition model for vaporized hydrogen peroxide using computational fluid dynamics to simulate the concentration distributions of vaporized hydrogen peroxide. A major drawback to using numerical simulations is the lack of sufficient data on boundary conditions for various types of building materials and hence. We also conducted the fundamental chamber experiment to identify the model parameters of wall surface decomposition model for targeting five types of building materials.

Impact of indoor ventilation efficiency on acetone inhalation exposure concentration and tissue dose in respiratory tract

A significant feature of the indoor environment is the heterogeneity of airflow and pollutant distributions,which are primarily dependent on ventilation systems.In the case of short-and high-concentration exposures to hazardous chemical pollutants,it may be necessary to precisely determine the concentration in the breathing zone or,more directly,the inhalation exposure concentration in the respiratory tract,rather than the representative room average concentration in an indoor environment,because of the non-uniformity of pollutant concentration distributions.In this study,we developed a computer-simulated person with a detailed respiratory system to predict inhalation exposure concentration and inhalation dose via transient breathing and reported a demonstrative numerical simulation for analyzing acetone concentration distributions in a simplified model room.Our numerical analysis revealed that the ventilation efficiency distribution in a room could change significantly by changing the design of the ventilation system,and that the inhalation exposure concentration estimated by a computer-simulated person could differ from the representative concentration,such as perfect-mixing or volume-averaged acetone concentration,by a factor of two or more.

Investigation of transient and heterogeneous micro-climate around a human body in an enclosed personalized work environment

Heterogeneous distribution of indoor environmental quality is known to have a great impact on human health,comfort,and productivity.A personalized work environment,that creates a localized and independent environ-ment with capsules or partitions,is being developed worldwide to provide workers with a space that enables undisturbed concentration on studying and working.However,the minimized interior space of a personalized work environment can immediately cause adverse health impacts for occupant if the air quality and thermal en-vironment in the personalized work environment is not controlled appropriately.Particularly,constant breathing can sharply increase the CO 2 concentrations in an interior space with an insufficient ventilation rate.In order to design a healthy and comfortable indoor environment,especially in a personalized work environment,it is important to predict precisely and comprehensively the transient and heterogeneous structure of the indoor envi-ronment formed around a human body.With this background,we have developed an in silico human model that integrates a computational human model(virtual manikin combined with thermoregulation models)and respi-ratory model(virtual airway)for estimating indoor environmental quality,targeting the microclimate around a human body and breathing zone with high accuracy.In this study,we report the applicability of a comprehensive in silico human model to estimate the environ-mental quality in a personalized work environment.A coupled analysis of heat and contaminant transfer with computational fluid dynamics was conducted targeting the space around the in silico human model installed in a virtual personalized work environment.The informative data including human thermal comfort and breathing air quality were obtained,potentially forming the basis for the development of a digital twin of the personalized work environment and contributing to the design of a healthy,comfortable,and productive personalized work environment.

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

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.

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

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.