http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
A Unified Conjugate Mass Transfer Model of VOC Emission
Deng, Baoqing,Kim, Chang Nyung 한국화학공학회 2003 Korean Journal of Chemical Engineering Vol.20 No.4
This paper develops a unified conjugate mass transfer model for VOC (Volatile Organic Compound) emission, which implies conjugate boundary condition for mass transfer at the material-air interface. Thus, no special treatment is needed at the material-air interface and numerical methods for conjugate heat transfer problem can be applied directly. The material-air partition coefficient has been taken into account and its effect is the same as specific heat in the energy equation. The equivalent diffusion coefficient in the material K_(ma)D_(m) instead of D_(m) characterizes the rate of mass transfer. The ratio K_(ma)D_(m)/D_(a) indicates whether VOC emission is controlled by the internal diffusion or not. The equivalent air-phase initial concentration C_(0)/K_(ma) determines the order of maximum concentration in the air. VOC emission contains two stages: the initial stage and the pseudo-steady stage when the emission rate nearly equals mass rate through the outlet of the air. Diffusion coefficient of VOC in the aterial has a significant effect on VOC emission in the two stages. The effect of partition coefficient on VOC emission depends on the value of K_(ma)D_(m)/D_(a).
Energy And Environmental Engineering : A Unified Conjugate Mass Transfer Model of VOC Emission
( Baoqing Deng ),( Chang Nyung Kim ) 한국화학공학회 2003 Korean Journal of Chemical Engineering Vol.20 No.4
This paper develops a unified conjugate mass transfer model for VOC (Volatile Organic Compound) emission, which implies conjugate boundary condition for mass transfer at the material-air interface. Thus, no special treatment is needed at the material-air interface and numerical methods for conjugate heat transfer problem can be applied directly. The material-air partition coefficient has been taken into account and its effect is the same as specific heat in the energy equation. The equivalent diffusion coefficient in the material K_(ma)D_(m) instead of D_(m) characterizes the rate of mass transfer. The ratio K_(ma)D_(m)/D_(a) indicates whether VOC emission is controlled by the internal diffusion or not. The equivalent air-phase initial concentration C_(0)/K_(ma) determines the order of maximum concentration in the air. VOC emission contains two stages: the initial stage and the pseudo-steady stage when the emission rate nearly equals mass rate through the outlet of the air. Diffusion coefficient of VOC in the aterial has a significant effect on VOC emission in the two stages. The effect of partition coefficient on VOC emission depends on the value of K_(ma)D_(m)/D_(a).
A multi-phase model for VOC emission from single-layer dry building materials
Baoqing Deng,Ru Li,Chang Nyung Kim 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.4
Abstract−A multi-phase model for the emission of VOC from dry building materials is developed. Dry building materials are viewed as porous media. A general adsorption isotherm is used to construct the concentration equation in the porous media. The boundary conditions at the material-air interface are presented for both CFD model and one compartment model. With the use of Henry’s law for the adsorption isotherm, an analytical solution is obtained and further is validated with the comparison of the experiment performed by Yang et al. [1], yielding a relatively good agreement. The effects of the model parameters on the emission are investigated in detail. Increasing the effective diffusion coefficient and the partition coefficient tends to promote the emission and increase the peak value of the concentration in the air. The effect of the porosity depends on the degree of the dependence of the effective diffusion coefficient on the porosity. When a weak dependence exists, the increase of the porosity tends to suppress the emission and decrease the peak value of the concentration in the air. However, when a strong dependence exists, the increase of the porosity tends to promote the emission and increase the peak value of the concentration in the air.
Numerical modeling of volatile organic compound emissions from multi-layer dry building materials
Baoqing Deng,김창녕,Songming Tang,김정태 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.4
This paper presents a mathematical model capable of simulating VOCs emission from a multi-layer material. The analytical solutions of the concentration in the air and the emission rate are obtained by Laplace transform and are validated through experiment. The influences of parameters of multi-layer material on the emission of VOCs are investigated in detail. Results show that the inner layer may act as a sink or a source of the top layer, depending on their initial concentrations and partition coefficients. For the case of the inner layer being a source of the top layer, the top layer becomes a barrier layer, reducing the emission rate of VOCs from the source. A low diffusion coefficient and a large thickness may promote the effect of the barrier on the emission rate, which helps to maintain better air quality in an indoor environment. The present solution is a longitudinal extension of a single layer problem, while the emission from multi-source is a transverse extension of a single layer problem.
Baoqing Deng,김창녕,Daqiang Ge,Li Lu,Di Ge,Jiajia Li,Yuan Guo 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.6
Radiation distribution in a photoreactor with multiple mediums is solved by the P-1 model. The UV lampis included in the computational domain. An additional source term method is presented to describe the generation ofUV light, which can avoid the use of analytical lamp emission model at the lamp surface. The boundary condition forincident radiation at the semi-transparent wall between adjacent mediums has been derived to link the P-1 equationsin adjacent mediums, which enables the present model to adapt to the photoreactor with complicated structure. Thepredicted incident radiation agrees well with the experimental data in literature. The effects of absorption coefficient,scattering coefficient and phase function of lamp plasma on the radiation distribution are discussed in detail.
Li, Jiajia,Deng, Baoqing,Zhang, Bing,Shen, Xiuzhong,Kim, Chang Nyung IWA Publishing 2015 Water Science & Technology Vol.72 No.8
<P>A simulation of an unbaffled stirred tank reactor driven by a magnetic stirring rod was carried out in a moving reference frame. The free surface of unbaffled stirred tank was captured by Euler-Euler model coupled with the volume of fluid (VOF) method. The re-normalization group (RNG) k-epsilon model, large eddy simulation (LES) model and detached eddy simulation (DES) model were evaluated for simulating the flow field in the stirred tank. All turbulence models can reproduce the tangential velocity in an unbaffled stirred tank with a rotational speed of 150 rpm, 250 rpm and 400 rpm, respectively. Radial velocity is underpredicted by the three models. LES model and RNG k-epsilon model predict the better tangential velocity and axial velocity, respectively. RNG k-epsilon model is recommended for the simulation of the flow in an unbaffled stirred tank with magnetic rod due to its computational effort.</P>
A numerical prediction on the reduction of microorganisms with UV disinfection
Chan Li,Baoqing Deng,김창녕 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.7
This paper investigates the three dimensional flow field and organism concentration in a UV disinfection channel. The modified P-1model is newly adopted to solve the UV intensity field. This modified P-1 model for radiative transfer can yield an accurate light intensity for even complicated geometries. The effect of UV light intensity on the disinfection of microorganisms has been considered in the species equation. Differently from existing literatures, this study has used the Euler method for the calculation of both the flow field and the concentration of organisms. The CFD modeling results are compared with existing experimental data [1] for a UV channel, which shows outstanding agreement. The effects of inlet velocity, absorption coefficients of lamps quartz and water on the disinfection efficiency are investigated. With a smaller inlet velocity and smaller absorption coefficients, higher disinfection efficiency has been obtained. The current CFD model has the capability to predict the performance of UV disinfection channels.
Numerical Simulation of Flow Field and Organism Concentration in a UV Disinfection Channel
LI Chan,DENG Baoqing,Kim Chang Nyung 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
This paper investigates the flow field and organism concentration in a UV disinfection channel in which vertical ultraviolet lamps are arranged in a staggered configuration. Turbulence is described by low Reynolds number k-ε turbulence model and standard k-ε turbulence model, respectively. P-1 method has been employed to solve the radiative transfer equation. The obtained incident radiation is used to compute the inactivation term in the species equation. The CFD results are in good agreement with the existing experimental data for the UV channel. For the flow field, the low-Reynolds number k-ε model is superior to the standard k-ε model. The approach velocity has a significant effect on the disinfection efficiency. The organism concentration at the outlet decreases fast to a low inlet velocity.