Junjie Liu

Tianjin University | tju

Cooking can emit high concentrations of particles and gaseous pollutants. Cooking has contributed to the major source of indoor air pollutants, especially for particle pollutants in residential buildings. Many studies already analyzed the emission characteristics of Chinese cooking-related UFPs and PM2.5, while less for the fine particle size distr...

Objective. The aim is to explore the effect and mechanism of indoor toluene exposure on orienting network. Methods. Twenty-two healthy adults were exposed to 0 ppb, 17.5 ppb, 35 ppb, and 70 ppb toluene for 4 hours, respectively. All subjects underwent attention network behavioral test, and their electroencephalographic activity was recorded simulta...

Over the past few years, surface ozone (O3) pollution has dominated China’s air pollution as particulate matter has decreased. In Beijing, the annual average concentrations of ground-level O3 from 2015 to 2020 regularly increased from 57.32 to 62.72 μg/m³, showing a change of almost 9.4%, with a 1.6% per year increase. The meteorological factors ar...

Smart control of window is a means of effectively reducing concentrations of indoor PM2.5 (particulate matter with aerodynamic diameter less than 2.5 μm) in naturally ventilated residential buildings without air cleaning devices. This study aimed to develop a reinforcement learning (RL) approach to automatically control window behavior in real time...

Fast fluid dynamics (FFD) could provide efficient airflow and concentration simulation. The commonly used turbulence model in FFD was RNG k-\(\varepsilon \) turbulence model which solved two transport equations to obtain eddy viscosity. To improve computing speed, this investigation implemented no turbulence model, Smagorinsky model and dynamic Sma...

The environment inside airliner cabins has attracted increasing attention. Instantaneous airflow, as one of the fundamental parameters of airflow field, affects aspects of the airliner cabin environment such as occupant comfort and airborne disease transmission. This study evaluated the characteristics of instantaneous airflow in airliner cabins wi...

With the spread of SARS-CoV-2 virus all over the world, the indoor air quality of commercial buildings has received intense attention. The evaluation of high-volume air purifiers (HAP, CADR≥800m³/h) is of unprecedented importance. According to the national standard GB/T 18801-2015, the purification performance of HAP and its three different replace...

Indoor air quality (IAQ) influences individual physical and mental health. Laboratory studies conducted in environmental chambers have shown that IAQ parameters such as temperature, humidity, CO 2 , and volatile organic compounds (VOCs) may impact participants’ productivity and cognitive performance. To better understand the influence of VOC at low...

With the development of IoT technology and low-cost indoor air quality (IAQ) sensors, the IoT-based IAQ monitoring platform has garnered significant research interest and demonstrated its potential in enhancing IAQ management. This study presents a comprehensive review of previous research on the development and application of IoT-based IAQ platfor...

Aerosols such as PM2.5 and PM10 can have an immense impact on human health. With the outbreak of SARS-CoV-2, it is urgent to filter aerosols by media filtration technology. Electrospun nanofibers are a promising material for achieving high efficiency, low resistance, light weight, and environmentally friendly air filtration. But research on filtrat...

In China, the regulation of a district heating (DH) station is mainly based on weather compensation control. This control method leads to large room temperature fluctuations and high energy consumption as the regulation of supply water temperature is solely based on outdoor meteorological parameters, which the influence of pipe delay, thermal inert...

The Himalayas, which include delicate and unspoiled ecosystems, have the third-largest glacier ice store in the world. Recent research reveals that anthropogenic and natural factors contribute to the deteriorating air quality in the region. Rising particulate matter (PM) levels might have devastating effects on the regional climate, hydrologic cycl...

The durability of polymer electrolyte membrane fuel cells (PEMFCs) is impacted by airborne contaminants, and it is necessary to install a cathode air filter to remove harmful pollutants. To learn more about the effect of key process variables (particle size and bulk density) on the adsorption performance of cathode air filters, the breakthrough beh...

Objective: While high concentrations of toluene are known to affect multiple human organ systems, research concerning the influence of immediate, short-term exposure to toluene indoors and at low concentrations is scarce. Here, we studied effects of indoor toluene exposure on neural network alterations during working memory (WM) encoding. Methods...

Humans are the primary source of particulate contamination in biological cleanrooms. Emitted particles can carry microorganisms, which severely reduces cleanliness. Due to the uncertainty of human particle emission rates, there is excessive ventilation in the cleanroom, resulting in waste of energy consumption. To resolve this problem, in this stud...

The health hazards of cooking oil fume (COF) exposure underscore the importance of effectively controlling air pollution in kitchens, especially during cooking. The effectiveness of ventilation for gaseous pollutant control deserves more attention due to its toxicity, odor and strong diffusivity. In this study, field measurements of 23 carbonyl com...

Although toluene is a typical in-vehicle pollutant, the impacts of in-vehicle toluene exposure on cognitive functions remain unestablished. Therefore, this study aimed to investigate the effects of short-term toluene exposure in vehicles on working memory based on neural oscillations. In total, 24 healthy adults were recruited. Each subject was exp...

The indoor environment has a significant impact on our wellbeing. Accurate prediction of the indoor air distribution can help to create a good indoor environment. Reynolds-averaged Navier-Stokes (RANS) models are commonly used for indoor airflow prediction. However, the Boussinesq hypothesis used in the RANS model fails to account for indoor anisot...

Air is a diverse mixture of gaseous and suspended solid particles. Several new substances are being added to the air daily, polluting it and causing human health effects. Particulate matter (PM) is the primary health concern among these air toxins. The World Health Organization (WHO) addressed the fact that particulate pollution affects human healt...

To reduce hazards due to the radon dispersion on occupants, careful consideration of multi-parameters of stratum ventilation is necessary, including air supply velocity, temperature, angle and air outlet position. In this study, the radon dispersion in a typical office with stratum ventilation was evaluated based on experimental measurements and co...

The airliner cabin environment is very important to the health of passengers and crew members, and the use of high‐efficiency particulate air (HEPA) filters for recirculated air in the environmental control systems (ECS) is essential for the removal of airborne particles such as SARS CoV‐2 aerosols. A HEPA filter should be high efficiency, low‐pres...

Renewable energy usage is continuing to increase as many countries worldwide are aiming to reach peak carbon emission and achieve carbon neutrality in the near future. One inherent problem with renewable energy is that its generation profile does not often fit well with the electricity usage profile. Therefore, it is of utmost importance that termi...

Conventional district heating (DH) substations in China use a feed-forward adjustment method that predicts the water supply temperature based on the outdoor temperature. This method does not consider the delay of the pipe network and the thermal inertia of the building. Most importantly, the lack of closed-loop feedback on the indoor temperature re...

The use of wet scrubbing to remove airborne molecular contaminants in cleanroom make-up air units has economic benefits and good application prospects. Still, problems with this method include low removal efficiency and large water consumption. To improve scrubbing performance, we built a full-scale scrubbing experiment platform using SO2 as the re...

Ammonia is a harmful gas in semiconductor cleanrooms. Activated carbons are widely used to remove ammonia. However, the existence of ambient moisture significantly impacts ammonia adsorption on adsorbents. Therefore, it is necessary to understand their adsorption performance on activated carbons to improve the product yield in semiconductor cleanro...

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...

The influence of volatile organic compounds (VOCs) on cognitive performance has been widely recognized but is still imperfectly understood. This article hypothesized that the influence of low concentrations of VOCs on cognitive function would occur without triggering subjective awareness. Toluene is a representative VOC commonly found in Chinese dw...

The operating resistance of a high-efficiency particulate air (HEPA) filter is affected by the environment and cannot be obtained through the dust holding capacity (DHC) test in the laboratory. For non-flat HEPA filters, studies on the effect of non-uniform deposition of particles on operating resistance were insufficient. We proposed an equivalent...

Despite accumulative literature reporting negative impacts of high‐concentration toluene, cognitive effects of toluene at low concentration are still unclear. Twenty‐two healthy college students were exposed in a closed environmental chamber to investigate the influence of indoor toluene on cognitive performance and brain activity. During each tolu...

The integration of air volume measurement and control has become a trend. However, one of the challenges in researching the integration of measurement and control dampers is that the coupling effect between local components (e.g., dampers, elbows, reducers and tees) in the duct system exerts a substantial effect on the measurement. This paper optim...

Indoor volatile organic compounds (VOCs) produce odours that reduce perceived air quality. Furnitures and indoor decoration are the main sources of indoor VOCs. Considering the increase in outdoor and indoor ozone concentrations, ozone, as a strong oxidant, can have an impact on indoor odour. Herein, medium-density fibreboard (MDF) and flame retard...

The falling film flow characteristics of a liquid on the surface of corrugated sheet packing are crucial for its mass transfer performance in various industrial applications. In this study, a falling film flow experiment with laser-induced fluorescence technology was conducted to validate the flow characteristics of a falling film simulated using c...

Wet scrubbers, with the advantages of high efficiency and efficient water savings, are often used in various industries. The internal gas-liquid two-phase pattern flow in a wet scrubber is complex and unstable, which affects the purification efficiency. However, the purification efficiency of a wet scrubber is rather difficult to measure in real ti...

The purpose of this field study was to evaluate the performance of heat recovery ventilation (HRV) systems in daily usage. A one-year field measurement campaign was conducted in 25 dwellings with an HRV system among three climate zones in China. The operating pattern of ventilation systems obviously varies from that in developed countries. The occu...

[This corrects the article DOI: 10.1016/j.buildenv.2021.108590.].

Epidemiological surveys have shown a significant association between indoor airborne particle exposure and adverse health effects. Duct-type electrostatic precipitators (ESPs) are effective in controlling airborne particles in buildings. Although several studies have examined the initial performance of duct-type ESPs, there are no comprehensive dat...

Both long-term on-site collection and off-site analysis methods were conducted to investigate airborne molecular contaminants (AMCs) in a semiconductor wafer cleanroom. The removal efficiency of SO2 and NO2 for chemical filters on a make-up air unit (MAU) in the cleanroom is approximately 50%, though this value does not meet the removal efficiency...

The low accuracy of Reynolds-averaged Navier-Stokes (RANS) modeling of urban airflow and airborne pollutant dispersion is attributed to model flaws and uncertainty contributed by closure coefficients. Previous studies have attempted to improve the performance of RANS modeling by ad hoc calibration of the turbulence model coefficients specifically f...

To achieve efficient ventilation and purification in the high-ceiling painting workshop is faced with the contradiction between effect and energy consumption. Understanding the characteristics of gaseous pollutants is of paramount importance for ventilation and purification system design. The composition and concentration of volatile organic compou...

Purification of ammonia in semiconductor cleanrooms is crucial to improve semiconductor yields and ensure standardized production. In this study, adsorption isotherms for ammonia on HKUST-1, UIO-66, and MIL-100(Fe) were acquired. Density functional theory (DFT) calculations for ammonia illustrated the adsorption mechanism at low pressure. Adsorptio...

The SARS-CoV virus spreads in the atmosphere mainly in the form of aerosols. Particle air filters are widely used in indoor heating, ventilation, and air-conditioning (HVAC) systems and filtration equipment to reduce aerosol concentration and improve indoor air quality. Requirements arise to rate filters according to their mass-based filtration eff...

Fast fluid dynamics (FFD) could provide informative and efficient airflow and concentration simulation. The commonly used turbulence model in FFD was Re-Normalization Group (RNG) k-ε turbulence model which solved two transport equations to obtain eddy viscosity. To reduce this part of time and further improve computing speed, this investigation imp...

It is difficult to quickly calculate the performance of the air filter media, especially regarding the dynamic particle-capture process. In this study, the geometric and topological features of the existing particle-deposition morphologies based on three different particle-capture mechanisms (diffusion, inertia, interception) were extracted, and a...

Cooking-emitted pollution is a major health concern in residential buildings. Compared to actively sampled cooking-emitted airborne pollutants with a focus on the intake portion through the respiratory system, the characteristics of splashed cooking particles deposited on surfaces are largely understudied. Using the 3D fluorescent microscopic passi...

The air distribution system in an airliner plays a key role in maintaining a comfortable and healthy environment in the aircraft cabin. To evaluate the performance of a novel displacement ventilation (DV) system and a traditional mixing ventilation (MV) system in an airliner cabin, this study conducted experiments and simulations in a seven-row cab...

The purification of indoor pathogenic microorganisms has become a topic of concern. The use of nonwoven media air filters causes high resistance, and the problem of noise limited their application under high air volume. Thus, we propose a micro-electrostatic filter, which has improved performance compared to an electrostatic filter, with a new type...

Air pollution has intensified in recent years. The rates of sulfur dioxide (SO2) and nitrogen oxides (NOx) contributing to air pollution have risen annually, imposing huge burdens on human health and industrial production. Among gas separation techniques, wet scrubbing exhibits superior economical and application value to simultaneously remove SO2...

A large amount of paint mist diffuses and escapes into the ambient air, forming oversprayed mist during the spraying process, which severely affects the environment in the spray booth and threatens worker health. To control the oversprayed mist and improve healthy work environments, a source control method is proposed: optimize the structure of the...

Buildings account for almost 40% of global energy consumption. Due to the high energy consumption of chilled water plants, various studies have optimized chiller loading in plants with multiple chillers for energy conservation. However, few studies have optimized dual-temperature chiller plants, even though better energy efficiency could be achieve...

Infectious disease hospitals must maintain pressure differences among rooms to direct the airflow toward the negative pressure isolation ward (NPIW) to prevent the spread of airborne pathogens. However, their values cannot be maintained easily in dynamic situations, especially when the door to the isolation room is open. There is a lack of guidelin...

The centrifugal pump is an important piece of equipment in production and industry. To improve the operating efficiency of the pump and reduce the energy consumption of the system, it is necessary to accurately monitor and analyse the status of the pump. The traditional pump test method must be connected with the system, which affects the integrity...

The urbanization has resulted in an increasing number of transformer stations, which has resulted insignificant building noise problems. However, noise problems persist because of inadequate noise characterization and the use of imperfect noise evaluation indexes for centralized substations. Based on this problem, a transformer vibration noise coup...

We analyzed the flow characteristics of a control valve in a secondary heating network and combined the optimization of the valve core structure with a method to solve the actual control problem of the secondary heating network. First, according to the common V-sector ball valve core, another three kinds of different V-sector ball valve cores were...

Cooking is a major source of indoor particulate matter, surpassing smoking. Large splashing oil fumes produced by water-oil interactions while cooking have received increasing attention for their common and significant hazards. However, the pollution of large splashing droplets is rather difficult to quantitatively measure with the current techniqu...

To evaluate the separate impacts on human health and establish effective control strategies, it is crucial to estimate the contribution of outdoor infiltration and indoor emission to indoor PM2.5 in buildings. This study used an algorithm to automatically estimate the long-term time-resolved indoor PM2.5 of outdoor and indoor origin in real apartme...

With split air conditioner (AC) becoming one of the most popular thermal comfort-related appliances in residential buildings in China, many issues, such as high energy consumption, have arisen. One crucial way to address these issues is to study the usage of split AC models, which can be greatly affected by occupant behavior. In this study, we cond...

Convective heat transfer on interior surfaces of the building envelope is important for predicting building energy consumption. The buoyancy effect is a key factor in convective heat transfer. Reynolds-averaged Navier-Stokes (RANS) models combined with the standard wall function are often used to simulate the convective heat transfer coefficient of...

During the COVID-19 pandemic, exposure to particles exhaled by infected passengers in commercial aircraft cabins has been a great concern. Currently, aircraft cabins adopt mixing ventilation. However, complete mixing may not be achieved, and thus the particle concentration in the respiratory zone may vary from seat to seat in a cabin. To evaluate t...

Buildings consume a large amount of energy across all sectors of society, and a large proportion of building energy is used by HVAC systems to provide a comfortable and healthy indoor environment. In medium and large-size buildings, the central cooling system accounts for a major share of the energy consumption of the HVAC system. Improving the coo...

Smart control of window behavior is a means of effectively reducing concentrations of indoor PM2.5 (particulate matter with aerodynamic diameter less than 2.5 μm) in naturally ventilated residential buildings without indoor air cleaning devices. This study aimed to develop a reinforcement learning approach to automatically control window behavior i...

Buildings account for a large portion of global energy consumption and CO2 emissions. Therefore, reducing the energy demands of buildings has become a global topic for sustainable development. A central cooling system accounts for a significant part of a building’s energy consumption. This study proposes a tap water-based free cooling system that r...

We reviewed 47 documents published 1967–2019 that reported measurements of volatile organic compounds (VOCs) on commercial aircraft. We compared the measurements with the air quality standards and guidelines for aircraft cabins and in some cases buildings. Average levels of VOCs for which limits exist were lower than the permissible levels except f...

Ventilation is an important means of reducing the concentration of volatile organic compounds (VOCs) in airplane painting hangars. Currently both an upside-supply and floor-exhaust (UF) system and an upside-supply and downside-exhaust (UD) system are used. However, these two conventional systems have low ventilation efficiency. To improve the VOCs...

With the wide use of multi-V filters in aircraft cabins, it is necessary to establish a pressure drop prediction and optimization model for multi-V HEPA cabin filters. Based on approximate solution of the Navier-Stokes equation and with the aid of CFD simulations, we developed an empirical equation for the overall pressure drop across a multi-V HEP...