Contaminant Dispersion Research Articles

Airflow design and source control strategies for reducing airborne contaminant exposure in passenger aircraft cabins during the climb leg

The climb leg is one of the most acceleration-intensive periods in a passenger aircraft flight. It was previously found that the passenger exposure to cough-released airborne contaminants during a climb may reach 2.8 to 3.0 times that compared to other legs (Elmaghraby et al., Science and Technology for the Built Environment, 2019, accepted. DOI:10.1080/23744731.2019.1576457). In the current study, airflow design and source control strategies are researched numerically for their ability to reduce cough-released airborne contaminant dispersion in the cabin of a Boeing 767-300 aircraft during a climb. Sulfur hexafluoride (SF6) was used to mimic the contaminant, which mainly includes cough-released particles in the size range 1.6 to 3 µm in diameter. The airflow design strategies involved altering the supply airflow direction and changing the supply airflow rate. The source control strategies involved changing the cough direction, varying the cough velocity or flow rate, and moving the cougher to different locations in the cabin. Among all cases, relocation of the cougher, changing the airflow direction, and modest increases in airflow rate exhibited the highest reduction in passenger exposure to contaminant compared to the baseline climb case. The exposure reductions were 0.5–0.7 times for the first case, 0.5–0.7 times for the second case, and 0.6–0.7 times for the third case.

Physiological responses and accumulation characteristics of turfgrasses exposed to potentially toxic elements

The tolerance and enrichment of potentially toxic elements (PTEs) in plants are the most important basis of phytoremediation technology for mining area soils. The aim of this research was to study PTEs tolerance, translocation and accumulation differences in three turfgrass species and the biochemical changes of plants and soils. Three turfgrass species were cultured on soils contaminated by single and compound PTEs. Pb, Zn, Cd and As concentrations and biochemical indicators in plant (root and shoot) and soil were determined. Moreover, the microbial communities in rhizosphere soil were analyzed. The studied plants showed strong tolerance and high enrichment ability to Pb, Zn, Cd and As in soil under different PTE concentration gradient stress. Festuca arundinacea had the strongest tolerance to PTEs, whereas Medicago sativa L. had the best tolerance to PTEs. Among all the measured growth or biochemical indicators, the relative growth rate and enzymatic activity of Orychophragmus violaceus were most sensitive to stress. The bioconcentration and translocation factors of Medicago sativa L. for Cd were 1.60 and 1.17, respectively, indicating that it was the most suitable plant for extracting Cd. Compared with other plants, Festuca arundinacea had the most significant effect on soil environment improvement, increasing the soil enzyme activities and microbial community after phytoremediation. This study indicates that Medicago sativa L. can be a potential phytoextraction plant to remove Cd, whereas Festuca arundinacea is more suitable as a cover plant to prevent the dispersion of contaminants in polluted soil.

City as an Object of Ecological and Economic Researches: the Example of Russian Cities

The growth of environmental pollution especially in big cities dictates the need to search for the reasons of this trend, most of which refer to the economic sphere. The aim of this work is not only to describe the state of environment in Russian cities with the population of 100 thousand inhabitants and more, but also to reveal the main economic factors that influence on the intensity of their environmental pollution. The ecological and economic analysis of Russian cities, fulfilled in this work, helped to identify the most unfavourable of them in terms of the level of environmental impact. The low quality of environment in these cities is largely due to natural and climatic conditions (bad conditions for contaminants dispersion) and specifics of their economic development: functioning of large industrial enterprises of ferrous and non-ferrous metallurgy, petrochemistry, construction industry. The conclusion is that to improve the environmental quality in these cities comprehensive social, environmental and economic solutions are required.

Experimental study of local thermal comfort and ventilation performance for mixing, displacement and stratum ventilation in an office

Satisfactory thermal comfort and efficient removals of airborne contaminants are crucial to the work efficiency and health of occupants. Different air distributions can generate distinct airflow patterns, thus affecting thermal comfort and ventilation performance. The experiments were conducted to study the performances of three air distribution methods (i.e. mixing ventilation (MV), displacement ventilation (DV) and stratum ventilation (SV)). Local thermal comfort was evaluated for the three air distribution methods with their individual thermally neutral temperatures. Three gaseous point pollutant sources located at the desktop, floor and manikin armpit respectively were applied to study the impact of the pollutant source locations on their ventilation performances. The distributions of air velocity, air temperature and contaminant concentration were measured. Results showed that a vertical air temperature difference of above 3 °C between the head and ankle levels appeared with DV, but the draught ratings (DR) under SV were higher than those under both MV and DV. Pollutant source locations exerted different effects on contaminant dispersion and contaminant removal effectiveness (CRE) for the three air distribution methods. SV always removed the contaminants effectively with all the three pollutant source locations to maintain good inhaled air quality, which was superior to MV and DV.

Assessment of the impact of landfill leachate on groundwater and surrounding surface water: a case study of Mekelle city, Northern Ethiopia

The aim of this study is to investigate the impact of leachate from municipal solid waste to groundwater and surface water quality surrounding the landfill site in Mekelle, Northern Ethiopia. The landfill is situated in carbonate geological formation where the effect of uncontrolled leachate release into the environment is evident at short distance of the site. The analysis of leachate sample showed elevated electrical conductivity (5280 μS/cm), chloride (256 mg/l), nitrate (92.6 mg/l) COD (1208 mg/l) and BOD (483 mg/l) in dry period. Samples of stream and groundwater in the vicinity of the landfill are characterized by high concentrations of TDS, bicarbonate, sulphate, chloride and nitrate. The elevated levels of these ions are attributed to seepage of landfill leachate with considerable input from local geology. The impact of leachate on water resources appeared to be higher in wet season when contaminant dispersion is accelerated by maximum infiltration and surface runoff. The elevated total dissolved solid and nitrate levels have proved that the water quality is unreliable for domestic water supply. Moreover, BOD (1.9–7.5 mg/l) and COD (42–160 mg/l) concentrations in the water samples were found to be exceeding the typical normal ranges, and were significantly higher in the surface water compared to the groundwater. This study highlights the need of leachate treatment mechanisms as remedial measures to prevent water pollution.

Direct or indirect exposure of exhaled contaminants in stratified environments using an integral model of an expiratory jet.

The risk of cross-infection is high when the susceptible persons are exposed to the pathogen-laden droplets or droplet nuclei exhaled by infectors. This study proposes a jet integral model to predict the dispersion of exhaled contaminants, evaluating the exposure risk and determining a threshold distance to identify the direct and indirect exposures in both thermally uniform and stratified environments. The results show that the maximum concentration of contaminants exhaled by a bed-lying infector clearly decreases in a short distance (<1.8m) in a uniform environment, while it maintains high values in a long distance in a stratified environment. The lock-up phenomenon largely weakens the decay of the concentration. The direct exposure of the receiver is determined primarily by the impact scope of the exhaled airflow, while the indirect exposure is mainly related to the ventilation rate and air distribution in the room. In particular, the distance of direct exposure is the longest (approximately 2m) when the receiver's breathing height is at the lock-up layer in a stratified environment. Our study could be useful for developing effective prevention measures to control cross-infection in the initial stage of design of indoor layouts and ventilation systems.

Are aircraft acceleration-induced body forces effective on contaminant dispersion in passenger aircraft cabins?

Numerical simulations for the effect of body forces due to aircraft acceleration on the airflow and contaminant dispersion in a model for a passenger aircraft cabin are performed in this study. Sulfur hexafluoride (SF6) was used as the in-cabin contaminant and served as a surrogate for cough particles in the size from 1.6 to 3.0 µm. It was found that those body forces have a significant impact on the contaminant dispersion phenomena and concentrations, especially during the climb leg, where the time-integrated concentration was 2.4 to 2.8 times its counterpart during the steady level (cruise) flight case at the two monitoring locations for most of the simulation time. However, the exposure to the contaminant did not change appreciably during the descent leg. Air velocities, on the other hand, increased noticeably during the climb and descent legs, leading to evident changes in the airflow patterns, airflow circulation magnitude, and, at some locations, airflow circulation directions. The current study has limitations, requiring detailed calculations while considering parametric variations. The findings warrant a closer investigation into the effects of body forces due to aircraft acceleration on the airflow and contaminant dispersion in various passenger aircraft cabins.

Monitoring Systems and Numerical Models to Study Coastal Sites.

The present work aims at illustrating how the joint use of monitoring data and numerical models can be beneficial in understanding coastal processes. In the first part, we show and discuss an annual dataset provided by a monitoring system installed in a vulnerable coastal basin located in Southern Italy, subjected to human and industrial pressures. The collected data have been processed and analysed to detect the temporal evolution of the most representative parameters of the inspected site and have been compared with recordings from previous years to investigate recursive trends. In the second part, to demonstrate to what extent such type of monitoring actions is necessary and useful, the same data have been used to calibrate and run a 3D hydrodynamic model. After this, a reliable circulation pattern in the basin has been reproduced. Successively, an oil pollution transport model has been added to the hydrodynamic model, with the aim to present the response of the basin to some hypothetical cases of oil spills, caused by a ship failure. It is evident that the profitable prediction of the hydrodynamic processes and the transport and dispersion of contaminants strictly depends on the quality and reliability of the input data as well as on the calibration made.

3D MRI measurements of the effects of wind direction on flow characteristics and contaminant dispersion in a model urban canopy

Three dimensional velocity fields and contaminant dispersion within an evenly spaced orthogonal array of cubic buildings (height = H) with a central tall building (height = 3H) were studied to examine the influence of tall buildings and wind orientation within an urban canopy. Mean velocity and contaminant data were collected using magnetic resonance velocimetry and magnetic resonance concentration methods. Two building orientations, each angled at 0° and 45° with respect to the bulk flow, were examined. The single tall building strongly influenced the distribution of the streamwise and vertical mass fluxes in both wind orientations. In particular, the tall building wake strongly influences how mass and momentum are transported downward into the building canopy. The contaminant dispersion pattern was dependent on the size of separation regions behind buildings and the wind orientation relative to the street canyons. A plume of contaminant trailed behind the tall building and was dispersed by the building wake turbulence. This dispersion was more rapid for the 45° wind orientation likely due to the wider wake in this case. The complex mean flow within the canopy plays a major role in controlling ground level dispersion when the wind is not aligned with the street canyons. The relatively simple geometry of the canopy and the detailed full field velocity and concentration data make this an ideal case for testing simulations.

Estimating distributions of airborne contaminants released by sources with dynamic strength and dynamic location by a probabilistic model

Characteristics of contaminant release source usually contribute significant impacts to dispersion of airborne pollutants. It is necessary and also desirable to grasp detailed information of contaminant distributions under various release patterns of contaminant sources. This study developed a Markov chain based probabilistic model to simulate transport and dispersion of airborne contaminants released by sources with dynamic strengths and locations. The proposed model takes the dynamic source strengths and locations into account by replacing elements of the state vector with values in accord with specific functions, which indicate strength and location variations. The particle phase simulations need to be initialized by comprehensive data of the flow field, which can be solved by CFD tools in advance. For the first step, the developed model is validated by experiment data from a 2D turbulence duct flow with a particulate source instantaneously releasing airborne particles. Then the new model is adopted to simulate contaminant dispersion of gaseous (or particles with small diameters) contaminant released by sources with dynamic strength and location. Results indicate that the proposed model is capable of predicting the behaviors of contaminant sources under various release patterns. The effects of dynamic contaminant sources on downstream regions in unidirectional flow are limited by the distances between the target region and source location. Accuracy of the present model is significantly affected by temporal intervals (the specified time step Δt) for sources with dynamic strengths and spatial intervals (computational grid scales) for sources with dynamic locations.

On the dispersion of contaminants released far upwind of a cubical building for different turbulent inflows

The effect of turbulent inflows on the transport of contaminants around a cubical building model is investigated using large-eddy simulation with the dynamic subgrid-scale eddy viscosity and eddy diffusivity models for the subgrid stress and scalar flux, respectively. Two different turbulent inflows, i.e. the synthetic turbulent inflow and the fully developed turbulent inflow, are examined in the simulations. The same concentration field is applied at the inlet for both velocity inflows. Two cases with and without the building are simulated for each inflow to examine the building effect on the dispersion of contaminants. While the simulated velocity fields from the two inflows are similar with each other upwind of the building, the concentration fields exhibit significant variations with the contaminants from the fully developed turbulent inflow case being distributed across a wider region and having significantly lower concentration compared with the synthetic turbulent inflow case. In the wake of the building the two velocity inflows result in insignificant differences among the two computed velocity fields but are shown to have a profound effect on the resulting concentration fields both in so far as mean values and statistics are concerned. The different building effects on the contaminant dispersion are caused by the different concentration fields approaching the building as a result of the different velocity inflows applied at the inlet. This work demonstrates the importance of applying proper velocity inflows at the inlet for simulating the contaminant transport in urban environments.

Modelling of distribution of aerosol emission with account of buildings and structures of NPPs

In the lack of experimental data and due to the rapid development of numerical modelling and computer hardware, computational fluid dynamics (CFD) is widely used to study wind field and contaminant transport around buildings. The ability to predict quantitative values for these processes is not so clear. CFD simulations work under neutral atmospheric conditions and are validated by the Gauss model. The Gaussian model is a mathematical distribution of the concentration of contaminants from NPP ventilation pipes. It is the most recommended model by the IAEA and most widely used because 1) it gives results consistent with experimental data, 2) it is quite easy to use, and 3) it is consistent with the aleatory nature of turbulence. Reynolds-averaged Navier-Stokes equations is the most widely used method in turbulent flow modeling and simulation. In this paper, the prediction of flow accuracy and propagation around buildings with a stack was examined using k-ε model. The numerical results were compared to Gauss model results. Contaminant dispersion was well predicted with k-ε model. It was also confirmed that the concentrations predicted by the CFD models were more diffused than those of the Gauss model and that the results depend on the position of the obstacles.

Assessment of displacement ventilation systems in airborne infection risk in hospital rooms.

Efficient ventilation in hospital airborne isolation rooms is important vis-à-vis decreasing the risk of cross infection and reducing energy consumption. This paper analyses the suitability of using a displacement ventilation strategy in airborne infection isolation rooms, focusing on health care worker exposure to pathogens exhaled by infected patients. The analysis is mainly based on numerical simulation results obtained with the support of a 3-D transient numerical model validated using experimental data. A thermal breathing manikin lying on a bed represents the source patient and another thermal breathing manikin represents the exposed individual standing beside the bed and facing the patient. A radiant wall represents an external wall exposed to solar radiation. The air change efficiency index and contaminant removal effectiveness indices and inhalation by the health care worker of contaminants exhaled by the patient are considered in a typical airborne infection isolation room set up with three air renewal rates (6 h-1, 9 h-1 and 12 h-1), two exhaust opening positions and two health care worker positions. Results show that the radiant wall significantly affects the air flow pattern and contaminant dispersion. The lockup phenomenon occurs at the inhalation height of the standing manikin. Displacement ventilation renews the air of the airborne isolation room and eliminates the exhaled pollutants efficiently, but is at a disadvantage compared to other ventilation strategies when the risk of exposure is taken into account.

Application of multi-monitoring methods to investigate the contamination levels and dispersion of Pb and Zn from tin mining in coastal sediments at Saphan Hin, Phuket, Thailand

Heavy metals have been detected in coastal regions, in the vicinity of former mining sites. The level of these heavy metals frequently exceed the safe limits in what represents an important aquatic source of food for human consumption. A thorough and conventional study into the levels of contamination in the suspected area is a costly but necessary exercise in order to inform any appropriate mitigating actions. This study demonstrates the benefits of integrating scientific investigating methods comprising chemical analysis using aqua regia and geo-electrical surveys, i.e., electrical resistivity imaging and induced polarization, to attain the approximate levels of contamination for both lateral and vertical landscapes in an efficient way. The demonstration to present the conformity and reliability of this joint methods is at Saphan Hin, situated on the southeastern coast of Phuket, Thailand. The site is located downstream of Bang-Yai canal; a potential intermediary carrying heavy metals especially Lead and Zinc from a number of mines where the nearest is approximately 4 km away. Saphan Hin is an important place marine fishery to supply to an increasing number of tourists to Phuket. The combined results from using all methods in this study are consistent in showing that the extent of the over-the-limit contamination can be found up to at least 200 m from the estuary, and with the decreasing depths from around 20 m to 50 cm at further distances from mainland, demanding urgent measures for the health of local people as well as tourists. A model to adapt these monitoring methods for implementation in operating mines is proposed as an early warning system to prevent any leakage probably occurring under normal conditions.

МОДЕЛИРОВАНИЕ ПРОНИКАЮЩЕЙ ТУРБУЛЕНТНОЙ КОНВЕКЦИИ И РАССЕЯНИЯ ЗАГРЯЗНЕНИЙ В ТЕРМИЧЕСКИ УСТОЙЧИВО СТРАТИФИЦИРОВАННОЙ СРЕДЕ

The urban-heat-island phenomenon and its associated circulation, driven by the energy generated by anthropogenic sources are found to be most intense at nighttime under clear skies and weak ambient wind. A thermal plume is generated by an underlying heat island in the form of an area source. The fundamental characteristics of most concern for a nocturnal heat island are its mixing height, intensity, temperature and turbulent kinetic energy distributions, and heat-island-induced circulation. To model the urban-heat-island structure it is necessary to describe correctly the turbulent penetrative convection in the case of near-calm conditions when the ambient wind speed approaches zero and the turbulent motion at the urban center is dominated by the thermal buoyancy force. In most existent mathematical models the turbulence of an urban-heat-island is parameterized. The principal aim of this investigation is the development of turbulent transport model for the simulation of turbulent urban-heat-island structure and pollutant dispersion in the stably stratified environment. The four-parametric turbulent model describing an evolution of fully turbulent low-aspect-ratio buoyant plume with no initial momentum and dispersion of contaminant from a ground-level source under calm and stable stratified conditions is formulated and evaluated.

100 Years of Progress in Applied Meteorology. Part II: Applications that Address Growing Populations

Abstract The human population on Earth has increased by a factor of 4.6 in the last 100 years and has become more centered in urban environments. This expansion and migration pattern has resulted in stresses on the environment. Meteorological applications have helped to understand and mitigate those stresses. This chapter describes several applications that enable the population to interact with the environment in more sustainable ways. The first topic treated is urbanization itself and the types of stresses exerted by population growth and its attendant growth in urban landscapes—buildings and pavement—and how they modify airflow and create a local climate. We describe environmental impacts of these changes and implications for the future. The growing population uses increasing amounts of energy. Traditional sources of energy have taxed the environment, but the increase in renewable energy has used the atmosphere and hydrosphere as its fuel. Utilizing these variable renewable resources requires meteorological information to operate electric systems efficiently and economically while providing reliable power and minimizing environmental impacts. The growing human population also pollutes the environment. Thus, understanding and modeling the transport and dispersion of atmospheric contaminants are important steps toward regulating the pollution and mitigating impacts. This chapter describes how weather information can help to make surface transportation more safe and efficient. It is explained how these applications naturally require transdisciplinary collaboration to address these challenges caused by the expanding population.

A POD Coupled Adaptive DEIM (POD-ADEIM) Reduced-Order Model for Incompressible Multiphase Flow in Porous Media

The multiphase fluid flow in porous media is one of the most fundamental phenomena in various physical processes, such as oil/gas flow in reservoir, subsurface contamination dispersion, chemical separation, etc. Due to its importance, the efficient and accurate solution and prediction of multiphase flow in porous media is highly required in engineering applications and mechanism studies, which has been a research hot spot with increasing interest in recent years. However, the strong nonlinearity implicated in the multiphase flow model has brought great challenges for the computation and analysis. In addition, the permeability in Darcy-type pressure equation is always represented as a high contrast coefficient, which further complicates the simulation difficulty especially for high fidelity prediction and decision-making process. In this study, we attempt to apply one popular global model reduction method, namely Proper Orthogonal Decomposition (POD), to accelerate the simulation of incompressible multiphase flow in porous media. The cornerstone of POD is processing information from a sequence of snapshots (or instantaneous solutions) to identify a set of basis functions to construct a low-dimensional space, the most energetic part of these basis functions is then selected to represent the solution of the original system. In our work, one key point is how to establish the accurate POD reduced order model (ROM) for incompressible mul-tiphase porous flow problems. According to Li et al. [1], the traditional Galerkin projection method (directly project the original governing equation into the low-dimensional space spanned by basis functions) is incapable of introducing the fluid saturation and permeability located on the cell face in POD-ROM for incompressible multiphase flow whether in homogeneous or heterogeneous porous media, thus we adopt the matrix operation method (project the discrete governing equation instead of the original governing equation into the low-dimensional space spanned by basis functions) to build the POD-ROM in this study. Based on the proposed POD-ROM framework, we use the implicit method to solve the (non-) wetting-phase pressure and saturation equations. However, in the implicit solution of the pressure and saturation equations, the standard POD-ROM alone sometimes cannot yield an expected acceleration owing to two main reasons: (1) the nonlinearity between pressure and saturation is sensitive, thus the saturation would change largely even with slight pressure change. And the small error of pressure results would lead to a large deviation of saturation, which in turn exerts negative impacts on the computation of pressure; (2) the complexity for computing a projected nonlinear term in POD-ROM still depends on the dimension of the original full-order system, it is unavoidable in conventional POD-ROM. Therefore, more POD modes are needed to be used in order to achieve the prescribed numerical accuracy, which could worsen the speed up efficiency of proposed POD-ROM. To further reduce the computational complexity of POD-ROM to speed up the implicit solution of pressure and saturation equations, another model reduction method called Discrete Empirical Interpolation Method (DEIM) [2] is applied to treat the projected nonlinear term in the proposed incompressible multiphase porous flow POD-ROM. Different from previous studies, we develop an adaptive DEIM (ADEIM) in this work to achieve a more flexible selection of the interpolation points. Combined the POD-ROM with ADEIM, a POD-ADEIM-ROM for incompressible multiphase flow in porous media is established. The computational efficiency and numerical accuracy of the proposed model is validated through several representative numerical examples. Numerical results indicate that an outstanding acceleration (2~3 orders of magnitude faster) without sacrificing numerical accuracy significantly is obtained from the proposed model when comparing to the traditional solution method that without any acceleration technique. In addition, the effects of POD mode number, the distribution of permeability field, and the mesh density on the overall performances of the proposed model are investigated in detail.

Challenging Geostatistical Methods To Represent Heterogeneity in CO2 Reservoirs Under Residual Trapping

AbstractGeostatistical methods based on two-point spatial-bivariate statistics have been used to model heterogeneity within computational studies of the dispersion of contaminants in groundwater reservoirs and the trapping of CO2 in geosequestration reservoirs. The ability of these methods to represent fluvial architecture, commonly occurring in such reservoirs, has been questioned. We challenged a widely used two-point spatial-bivariate statistical method to represent fluvial heterogeneity in the context of representing how reservoir heterogeneity affects residual trapping of CO2 injected for geosequestration. A more rigorous model for fluvial architecture was used as the benchmark in these studies. Both the geostatistically generated model and the benchmark model were interrogated, and metrics for the connectivity of high-permeability preferential flow pathways were quantified. Computational simulations of CO2 injection were performed, and metrics for CO2 dynamics and trapping were quantified. All metrics were similar between the two models. The percentage of high-permeability cells in spanning connected clusters (percolating clusters) was similar because percolation is strongly dependent upon proportions, and the same proportion of higher permeability cross-strata was specified in generating both models. The CO2 plume dynamics and residual trapping metrics were similar because they are largely controlled by the occurrence of percolating clusters. The benchmark model represented more features of the fluvial architecture and, depending on context, representing those features may be quite important, but the simpler geostatistical model was able to adequately represent fluvial reservoir architecture within the context and within the scope of the parameters represented here.

Transport of oxygen into granitic rocks: Role of physical and mineralogical heterogeneity

The rock matrix of granites is expected to be an important buffer against the dispersion of contaminants, e.g. radionuclides, and against the ingress of oxygenated glacial meltwater. The influence of matrix heterogeneity on O2 diffusive transport is assessed here by means of numerical experiments based on a micro-Discrete Fracture Network (micro-DFN) representation of the diffusion-available pore space along with random realisations of idealized biotite grains, to simulate the heterogeneous nature of granitic rocks. A homogeneous-based analytical solution is also presented and used to assess possible deviations of the numerical experiments from the assumption of homogeneity. The analytical solution is also used to test upscaled values of mineral surface area. The numerical experiments show that the matrix behaves as a composite system, with the coexistence of fast and slow diffusive pathways. This behavior is more evident at low Damköhler numbers. Our interpretation of the numerical experiments points out the importance to properly characterise the heterogeneity of the rock matrix.

Evaluation of the eddy viscosity turbulence models for the simulation of convection–radiation coupled heat transfer in indoor environment

This paper presents a numerical evaluation of the eddy viscosity turbulence models (the zero-equation, one-equation, k-ε group and k-ω group models) in terms of CFD modelling of convection-radiation coupled heat transfer in indoor environment. The results show that all the models except the zero-equation model have acceptable accuracies to predict the bulk air temperature. However, the zero-equation and one-equation models seriously overpredict the convective heat transfer coefficient at the heater surfaces while the k-ε group models severely underpredict it, ultimately resulting in the incorrect predictions of the thermal buoyancy flows and contaminant dispersion. On the contrary, the k-ω group models perform best to calculate the convection-radiation heat split, which is critical to the successful predictions of the near-wall flow field and distribution patterns of the contaminants. This study also demonstrates the importance of simultaneously considering the convective and radiative heat transfer mechanisms when evaluating the turbulence models for indoor environment simulations.