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To better understand turbulence, it is necessary to re-examine the treatment of viscous energy dissipation by the Navier-Stokes (N-S) equations. In this paper, a local viscous energy in a fluid is defined using the product of the local viscous force and the velocity. The gradient of this viscous energy represents the local change rate of viscous energy, in which the sum of all the positive terms describes the irreversible, viscous energy loss in the motion of a viscous fluid, and can be directly used to establish the thermodynamic energy equation. The remainder of the local change rate of viscous energy includes the velocity components. The parts other than the velocity components represent the viscous force components of the fluid in all directions, which can be added to the Euler equation to establish the momentum equation of viscous fluid. Then, new momentum and thermodynamic energy equations for general, compressible, viscous fluid flows are derived, being different from the traditional N-S equations. The term of divergence of velocity in the N-S momentum equation, which is directly related to the local change of density in the fluid, does not appear in the new equation, indicating a decoupling between the compressibility and the viscosity. The viscous force terms in each direction in the N-S momentum equation includes the partial derivatives of the velocity components in the other two directions, while this is not the case in the new equation.

In the field of micro and mesoscale combustion, the feature of flame-wall thermal coupling is of great significance because of its small scale nature. Thus, this work provides a comprehensive heat transfer analysis in cylindrical combustors from the perspective of numerical simulation. The combustor has a fixed length-to-diameter aspect ratio of 10, and the channel diameter is scaling up from 1 mm to 11 mm to explore the influence of chamber dimension on heat transfer and flame structure. The distribution of convective and radiative heat flux on inner surface, contribution of thermal radiation are given. Moreover, the role of radiation in flame structure is analyzed, and the convective and radiative heat losses are quantitatively analyzed. We find that radiative heat flux is smaller compared to convective heat flux, and the proportion of radiative heat flux becomes larger with an increasing diameter. Thermal radiation does not change the flame structure when the diameter is less than 3 mm. When the diameter is greater than 5 mm, thermal radiation changes the location of flame front. The heat loss becomes larger at a smaller diameter, and heat loss ratio can reach approximately 73.6% in the combustor with diameter of 1 mm.

In this paper, a new measurement method based on flame emission spectrometry (FES) is applied to establish a functional model between Na concentration (CNa), the temperature (T), and the radiation ...

Effects of radiation reabsorption on the burning flux of freely propagating laminar premixed flames at atmospheric and elevated pressures were numerically investigated for CH4/O2/N2/CO2 mixtures. Models with SNBCK 9 bands and 7 bands based on the spectral band lumping for H2O, CO2, CO and CH4 were developed to improve the computational efficiency. It is found that the burning flux is promoted by the upstream radiation reabsorption and with increasing CO2 concentration. Furthermore, with increasing pressure, radiation reabsorption first increases and then reduces the burning flux because of the corresponding increases of the reabsorption efficiency and the optical thickness, respectively. The blockage of radiation emission from the burnt mixture due to the increased optical thickness is dominant with the addition of the stronger radiative species CO2 at higher pressures. Extensive computation further demonstrates that, compared with the benchmark case of 367 bands, the SNBCK 9 bands lumping retains good accuracy while substantially facilitates the computational efficiency.

A candle flame is experimentally studied using a hyperspectral imaging device in this paper. The distributions of temperature and wavelength-dependent emissivity are calculated using a Newton-type iterative method. The results show that the spectral radiation intensity increases from the outside to the inside in the candle flame, and at the same spatial point, the intensity increases as the wavelength increases. The highest temperature of the candle flame is about 1980 K, occurs close to the flame border, indicating the most vigorous reaction. Additionally, the radiation characteristics of the candle flame differ from a gray-body, and the emissivity of the flame decreases as the wavelength increases.

Generally, there is no common method for directly and quantitatively evaluating computational errors in the calculation of radiative transfer. A method for quantitatively evaluating the accuracy in calculation of radiative transfer using the Monte Carlo method (MCM) is proposed, which is based on setting a radiative transfer enclosure in an isothermal and radiative equilibrium state, i.e. a state that equates exactly to a blackbody. For a gray emitting, absorbing, isotropically scattering, cubic enclosure bounded with diffusely emitting and reflecting surfaces, the computational accuracy and efficiency of the MCM are examined under fixed, constant surface emissivity of 0.5 and medium scattering albedo of 0.5. The concept of Mean Optical Thickness per Element (MOTE), that is the product of the absorption coefficient and the average length of three coordinate directions of the discrete space elements, is proposed to serve as a key scaling parameter to evaluate the calculation errors. When the MOTE is less than around 0.1, the errors for the surface elements reach a minimum level, even if the mesh density continues to increase. Scaling laws have been set up to relate the minimum errors for both the surface elements and space elements with the variation in the number of energy bundles (NEB). A desirable calculation error level is set as 1.0% for radiative heat transfer with an acceptable cost, for which the minimum NEBs are 3000 and 750 for the surface and space elements, respectively. For the surface elements, a scaling law relating the NEB and the maximum MOTE has been obtained that will enable the desirable error not to be exceeded; for the space elements, achieving the desirable error is dominated by the NEB, not the MOTE. It is stated that the cases studied in the paper have many limitations, and additional research should be done in the future to address the real cases of interest.

This paper presents a real-time measurement method for the skin temperature of the human arm. In this method, the air temperature close to the arm skin is measured via large lateral shearing interferometry, thus avoiding the possible influences of the different physical characteristics of different people, while maintaining the advantages of optical measurement, including its noncontact, noninvasive, and rapid features. The method captures the real-time fringe patterns generated using a parallel-sided plate when a collimated laser light beam transfers through the air surrounding the arm to be measured. Additionally, the phase difference distribution caused by the temperature difference is calculated in combination with the background fringe patterns. The phase difference in the light close to the arm skin is then estimated via a linear fitting method. Accordingly, based on the size parameters of the arm cross section and the ambient temperature monitored in real time, the air temperature close to the arm skin, which is considered equal to the arm skin temperature, is determined while considering the heat conduction effect. Experimental measurements of the temperature of human arm skin were conducted using the proposed method, and the axillary temperatures of the same person before and after the experiments were also measured using an electronic thermometer and a mercury thermometer. Good agreements were found, verifying the reliability of the proposed method. Moreover, based on this method, the possibility for the construction of a real-time body temperature measurement system is also discussed.

Coal-fired power generation is the main source of CO2 emission in China. To solve the problems of declined efficiency and increased costs caused by CO2 capture in coal-fired power systems, an integrated gasification fuel cell (IGFC) power generation technology was developed. The interaction mechanisms among coal gasification and purification, fuel cell and other components are further studied for IGFCs. Towards the direction of coal gasification and purification, we studied gasification reaction characteristics of ultrafine coal particles, ash melting characteristics and their effects on coal gasification reactions, the formation mechanism of pollutants. We further develop an elevated temperature/pressure swing adsorption rig for simultaneous H2S and CO2 removals. The results show the validity of the Miura-Maki model to describe the gasification of Shenhua bituminous coal with a good fit between the predicted DTG curves and experimental data. The designed 8-6-1 cycle procedure can effectively remove CO2 and H2S simultaneously with removal rate over 99.9%. In addition, transition metal oxides used as mercury removal adsorbents in coal gasified syngas were shown with great potential. The techniques presented in this paper can improve the gasification efficiency and reduce the formation of pollutants in IGFCs.

Coal-fired power generation is the main source of CO2 emission in China. To solve the problem of efficiency decline and cost increase caused by CO2 capture of coal-fired power generation, Prof. Peng (Peng and Han 2009) proposed an integrated gasification fuel cell (IGFC) power generation technology. The interaction mechanism of coal gasification purification, fuel cell and other components need to be further study in the IGFC. To develop new technology for coal gasification and purification, we studied gasification reaction characteristics of ultrafine coal particles, ash melting characteristics and effects on coal gasification reaction, the formation mechanism of pollutants and developed an elevated temperature pressure swing adsorption rig for H2S and CO2 simultaneous removal. The results show that the Miura-Maki model appropriate to perform gasification kinetics of Shenhua bituminous coal and the predicted DTG curves fit the experimental data well. The designed 8-6-1 cycle procedure can effectively remove CO2 and H2S simultaneously, and the removal rate is over 99.9%. In addition, the transition metal oxides used as mercury removal adsorbents in coal gasification syngas has great potential. The technique presented in this paper can improve the gasification efficiency and reduce the formation of pollutants for IGFC.

The statistical narrow band (SNB) and the statistical narrow band correlated-k (SNBCK) models were used with HITRAN2008, HITRAN2012, and HITRAN2016 databases, in order to demonstrate the effect that the different HITRAN database versions had on the accuracy of the SNB and SNBCK calculations. The line-by-line (LBL) calculation was based on the HITEMP data. Eight cases were calculated using the LBL, the SNB, and the SNBCK models in a one-dimensional enclosure between two parallel plates filled with CO2, H2O, or a mixture of both. The results demonstrated that the radiant flux and the source of the SNB and SNBCK models based on the HITRAN2012 and HITRAN2016 databases were in good agreement. This was not true in the 0.1 m short path. The improvement in accuracy from the HITRAN2016 to the HITRAN2012 database was not as accurate as the improvement from the HITRAN2012 database to the HITRAN2008 database. The results calculated using the same HITRAN database by the SNB model were more accurate than those obtained with the SNBCK model. And the lack of contribution of the hot lines in the three HITRAN databases leads to the relative error values of more than 20% on the radiant flux. This indicated that the HITRAN databases are not suitable for engineering calculations at a higher temperature.

The gas temperature fields of axisymmetric co-annular laminar diffusion ethylene flame jets in air and oxygen-enriched atmospheres were measured and visualized using large lateral shearing interferometry. The relationship between the refractive index and the temperature is obtained using a state equation and the Gladstone–Dale relation. Considering the unknown local gas composition can be a potential source of error, local gas compositions provided by corresponding numerical simulations were employed. The spatial resolution of the temperature fields was 0.1 mm/pixel. The temperature results obtained using hot air assumption and simulated local composition indicate that deviations of up to 400 K occur at the bottom part on the centerline, whereas at larger axial or radial positions, the deviations could be less than 50 K. The results are also validated by comparison with CARS. In addition, compared with flames under air atmosphere, significant deviations occurred in a greater region of oxygen-enriched flames.

This paper proposed a novel two layer hierarchical Takagi-Sugeno fuzzy hyperbolic tangent static model control scheme for a circulating fluidized bed (CFB) boiler thermal power unit to cope with the complex nonlinearity and large inertia performance which make its existing PI type load-fuel control loop not functioning normally. In the upper layer, a reference governor with Takagi-Sugeno fuzzy hyperbolic tangent static model control algorithm was developed to yield a compensation for the external load command of the existing PI type load-fuel control loop in the lower layer. By constructing a new quadratic integration Lyapunov function, the stability condition of proposed control system was derived. While implemented in the decentralized control system (DCS) of CFB boiler, the reference governor was constructed and adopted the cubic variables hyperbolic tangent function algorithm which can oppose effectively the nonlinearity and large inertia performance. The experimental results shown that the proposed hierarchical fuzzy hyperbolic tangent static model control scheme can improve the control performance of the PI type load-fuel control system obviously, weaken the fluctuation in the main steam pressure and bed temperature apparently and make the controlled system more stable.

A SNBCK/DRESOR combined method is presented in order to predict the radiative heat transfer of gas and soot mixtures at different temperature configurations. The mixtures of the combustion gases (H2O, CO2, CO) and the different soot loadings were analyzed to explore the influence of the soot on the non-gray radiation. The radiative source and the intensities with high directional resolution calculated by the DRESOR method were investigated at different temperature configurations. The accuracy of the SNBCK/DRESOR model was also analyzed and compared to the LBL/DOM approach, where the relative errors were less than 4%. The results indicate that the SNBCK/DRESOR method has a better efficiency than the SNBCK/DOM method.

A measurement system consisting of a large lateral shearing interferometry and an experimental setup which can be used under high pressures (pressure ≤ 10 MPa) has been built up to measure the binary gas diffusion coefficients. Fringe pattern in the large lateral shearing interferometry can be as simple as the holographic interferometry. The preliminary experimental results of the diffusion coefficients of CO2 and CH4 in O2 near room temperature and atmospheric pressure have been obtained. Comparison of the experimental results with the data calculated by the Fuller correction and the formulas of Landolt-Bornstein database shows that our measured results are accurate and credible. The experimental system used in this study is suitable for the measurement of the gas diffusion coefficients under high pressures which have not been thoroughly experimental studied.

A novel planar micro-combustor with four-corner entrances is proposed by considering high and uniform outer wall temperature distribution used in micro thermo-photovoltaic generator. For this, a three-dimensional numerical model with detailed chemical mechanism, transport, and heat transfer and a thermo-photovoltaic energy conversion model are developed to examine its performance. Results show that the proposed micro-combustor has excellent wall temperature uniformity because a uniform distribution of high-temperature zones of four individual flames is formed in the combustion chamber. Thermal performance and energy efficiency of the proposed micro-combustor are better than conventional micro-combustor at a low flow rate (m) and large equivalence ratio (φ). Additionally, the implemented plate-insertion strategy effectively overcome the deterioration of combustor performance under higher m or lower φ. Proposed micro-combustor with plates insertion has the largest wall temperature and energy efficiency, no matter what φ and m are adopted. Plates extend the fluid ravel path and produce some recirculation zones, which promotes heat transfer, preferential diffusion, and flame anchoring, while its pressure loss is larger. Of all the tested cases, the system efficiency reaches a maximum of 6.39%, corresponding to 12.1 W electricity output. This work provides effective combustor design and research insights to develop high-efficiency micro-power system.

This paper proposes a hyperspectral imaging technique for capturing radiative images at a high temporal–spatial resolution, for the purpose of spectrally visualizing the instantaneous combustion behaviors of single coal particles. We initially use a hyperspectral imaging device to record the combustion processes of two types of single pulverized coal particles on a McKenna flat-flame burner. From the snapshot images captured by the device, we observe the combustion processes, ignition characteristics, flame morphologies, and sizes of the two single coal particles. The observations indicate that the two single coal particles undergo volatile release/combustion and char ignition/oxidation during the luminous combustion process; moreover, both particles exhibit homogeneous ignition characteristics under the experimental conditions. Furthermore, based on the spectral radiative intensity images obtained via the device, the soot temperature and volume fraction images of the two single coal particles in the envelope flame are obtained at different burning times. Thereafter, the influences of the combustion behaviors and soot formation mechanisms on the distribution rules of the soot temperature and concentration at different combustion periods are discussed. Finally, the temperature and apparent spectral emissivity values of the two single char particles during the char oxidation process are also calculated to analyze their combustion behaviors. The results show that the temperature changes within a relatively narrow range with respect to the burning time during the oxidation stage, whereas the spectral emissivity continues to increase with the oxidation of chars and subsequently decreases.

The Distribution of Ratios of Energy Scattered by the medium Or Reflected by the boundary surface (DRESOR) method based on the Monte Carlo method is an important new approach to solve the radiative transfer equation accurately and efficiently. This method has been applied extensively for the detection and analysis of the furnace flame temperature. However, the discrete method, the number of direct incident radiation directions (DIRDs), and the number of scattered or reflected energy beams (SREBs) lack quantitative references. Therefore, in this paper, the effects of different discrete methods, the number of DIRDs, and the number of SREBs on the radiative heat flux, divergence error, and computational efficiency of three-dimensional homogeneous absorbing, emitting, and scattering media are analyzed. The results show that the random discrete method of the DIRD for the space element substantially reduces the divergence error of the radiation heat flux. The uniform discrete method of the DIRD should be used for the surface element to minimize the error of the radiation heat flux error. In addition, the relative error of the DRESOR method is reduced to 0.004, and the figure of merit reaches the maximum when the number of DIRDs is about 1000, the number of SREB is 500, and the scattering albedo is less than 0.8. The fitted equations describing the relationship between the calculation errors and the number of SREBs for the surface and space elements are obtained for different scattering albedos. An increase in the number of DIRDs and SREBs does not significantly reduce the calculation error. The results provide a quantitative reference for determining the parameters of the DRESOR method in radiant heat analysis.

The Distribution of Ratios of Energy Scattered by the medium Or Reflected by the boundary surface (DRESOR) method, one of the most effective methods to solve the radiation intensity problem with high directional resolution in radiation transfer analysis, suffers performance degradation as the medium scattering albedo becomes large. A scheme is put forward to subdivide the discrete energy beam step length, and take its infinitesimal limit to calculate the scattering/reflection fraction (DRESOR value) with high efficiency and precision. The preliminary simulation results show that when the scattering albedo is greater than 0.5, the optimized DRESOR method can greatly reduce the calculation time and improve the calculation accuracy.

A simple diagnostics method was presented that uses a low-cost camera to simultaneously reconstruct 2D distributions of flame temperature and soot concentration in laminar diffusion axisymmetric flames. A Manta G-504 camera with one million effective pixels was utilized for data collection, equipped with the lens type Computar TEC-55 with one customized double-bandpass filter mounted on front of the camera. This setup was used to obtain 615 and 517 nm monochromatic radiation flame images. Firstly, the spectral response spectrums and the directional emissive powers of the measurement system were calibrated. Then, the Tikhonov regularization method was used for inversing the spectral emission source term. Secondly, neglecting the self-absorption effect, the local temperature T ( l ) and soot concentration f v ( l ) could be calculated based on the ratio method. Finally, re-considering the self-absorption effect, the iterative computational method was implemented to update the calculated temperature T ( l ) and soot concentration f v ( l ) . The resulting measurements reported in this study are in good alignment with the LII method and emission spectrum method. The proposed diagnostic method was found to be capable of simultaneous reconstruction of 2D distribution of soot temperature and concentration.

Studies on coal pyrolysis via a thermogravimetric analyzer (TGA) are typically performed under a variety of temperature increases beginning at ambient temperature. A main limitation in these procedures is that the reaction temperatures (generally lower than 1000 °C) are typically lower than those met in pulverized coal boilers and ash flow temperatures (AFTs; generally higher than 1100 °C). In this paper, five Chinese coals are clarified to low- or mid-AFT coals as their AFTs increase. They were then prepared in TGA at several temperatures below or above their AFTs under N2 atmosphere for approximately 30 min after a heating procedure at a rate of 80 °C/min. The coal and residual char samples were collected and analyzed via X-ray diffraction and compared to the chemical thermodynamic calculation. The secondary weight loss appeared between 1200 and 1450 °C in the TG curves of four mid-AFT coals but not the low-AFT coal. The results showed that this secondary weight loss was caused by the carbothermal reduc...

The gas temperature fields of axisymmetric co-annular laminar diffusion ethylene flame jets in air and oxygen-enriched atmospheres were measured and visualized using large lateral shearing interferometry technique. Seven cases of reconstructed temperature fields were investigated using various compositions of fuel/oxidant with an average correction factor. The phase difference field were obtained using a fringe trace algorithm. A discrete Abel inversion process was adopted to resolve the refractive index distribution from the line-of-sight integrated data. The peak temperatures of the flame varied between 1980 K and 2050 K using air as the oxidant and increased to more than 2150 K when oxygen was added. Two separate high temperature zones, one located at the side edge of the flame, the other in the upper part of the flame around the centerline of the burner were observed in four of the seven instances of high mixture stoichiometry. The proposed methodology was verified to be suitable for the reconstruction of temperature distributions from the experimental measurement results.

Three kinds of atmospheres, namely, air, oxygen-enriched air, and oxygen/carbon dioxide atmospheres, and a total of ten axisymmetric coflow ethylene laminar flames are experimentally studied using a hyperspectral imaging device. 2-D distributions of the local emission source term in the visible and near-infrared ranges are reconstructed using the least-squares method. Then the distributions of temperature and absorption coefficient are calculated using the Newton-type iterative method, while the wavelength dependence of the absorption coefficient is fitted by polynomials. For the nonoptically thin flame, an iterative algorithm is adopted by substituting the absorption coefficients back into the reconstruction. The experimental results show that there exists a local temperature peak near the flame edge and the flame root. Additionally, for an oxygen-enriched atmosphere, there also exists another local temperature peak in upper center part of the flame in an air/oxygen atmosphere or in the upper edge part in an oxygen/carbon dioxide atmosphere. The results also reveal that the reduction in the flow of ethylene will result in the decrease in the highest soot volume fraction, and a higher oxygen content will generate a higher temperature peak and a lower soot volume fraction peak in an oxygen-enriched air atmosphere, but a higher soot volume fraction peak in an oxygen-enriched oxygen/carbon dioxide atmosphere. In addition, in an air atmosphere or an atmosphere with a large quantity of carbon dioxide, there will be another local peak of the soot volume fraction in the upper center part of the flame, which may be aggravated by the reduction in the amount of ethylene.

Through using a new thermal analysis model and a method of coal/char combustion, the minimum ignition temperature and minimum ignition heat of three different ranks of pulverized coal char were measured by simultaneous Thermogravimetry and Differential Scanning Calorimetry (TG-DSC) experiments. The results show that the ignition of coal char occurs in the range between the minimum ignition temperature and the inflection-point temperature. The thermal acceleration and its gradient G T increase with increasing heating rate and decrease with increasing coal char rank. The higher the G T of the coal char, the more easily the ignition occurs and more rapidly the burning and burnout occur. The data show that the G T of coal char of SLH lignite is 1.6 times more than that of coal char of ZCY bituminous and JWY anthracite in ignition zone, and 3.4 times in burning zone. The characteristic temperatures increase with increasing temperature of prepared char, heating rate and char rank. Moreover, the T ig ,max calculated in DSC experiment is approximately in line with the ignition temperature obtained in the entrained flow reactor, which demonstrates the feasibility of the proposed theory.

A dynamic mathematical model of the fly ash transport and sticking in a pulverized-coal boiler was developed by a direct simulation Monte Carlo (DSMC) method. In this paper, the critical velocity model was used to calculate ash sticking rate during the initial deposition stage and the viscosity model was used to describe the outer layer deposition. The dynamic process of ash deposition was simulated and the distributions of adhesion particle size were obtained. The simulation results show that the ash deposit thickness increases by 47.52% with the load increases by 20% and the Alkaline Earth Metal (AAEM)-rich enhanced deposits of bulk ash particles are apparently stickier than the other ash particles. The experiments were carried out at two different loads and the morphology of ash deposit samples was analyzed by SEM/EDS. The propotion of particle size in 2 μm were most in the deposition inner layer. The mean deposit thickness calculated by the DSMC method agreed with the measured value and the maximum relative error was 5.23%. A parametric study quantified the influence of changed operational conditions and ash material properties on the deposit formation process.

In this paper, a mathematical model of the fly ash deposition in a 660 MW supercritical once-through boiler was developed. The mechanism of particle-particle and particle-wall collisions has been considered. Particle collision is modeled by a direct simulation Monte Carlo (DSMC) method. Three submodels (impaction, thermophoresis, and sticking) were included in the mathematical model. In the ash deposition model, the critical velocity model was used to calculate the ash sticking rate during initial deposition, and the viscosity model was used for the outer layer deposition. An ash deposition probe was inserted into the peephole and ash deposits were collected. The morphology of these samples was analyzed using SEM. The deposit thickness and the distributions of adhesion particle size were obtained by mathematical model. The mean deposit thickness calculated by the DSMC method agreed with the value measured by the ash deposition probe with the relative error within 3.79%. The simulation results show that the deposition inner layer consists of fine particles less than 10 μm in size and sticky fine particles were selectively captured during the initial deposition stage. The DSMC method may be a practical alternative for studies of ash deposit formation.

There has been a controversy about the reactivity of coal/char combustion under oxyfuel and air conditions. The conversions of NCP anthracite and DT bituminous coal chars were studied under different atmospheres, using simultaneous thermogravimetry and differential scanning calorimetry (TG–DSC). A model of the intrinsic reaction rate was developed to obtain the variable activation energy at different temperatures and char conversion ratios in terms of a TG–DSC curve only. In the endothermic stage, the chemisorption obeys the same mechanism in O 2 /CO 2 , O 2 /N 2 and O 2 atmospheres, in which the reaction order is about 0.48 in the n th-order model, while in CO 2 is a zeroth-order reaction; both of them are not affected by coal rank. The chemisorption activation energy of CO 2 is less than that of O 2 . The chemisorption activation energies in O 2 /CO 2 are more than that in either 100% CO 2 or 100% O 2 , showing that both O 2 and CO 2 compete for the same active sites. The char-O 2 chemisorption is inhibited by the char-CO 2 chemisorption, resulting in a lower reactivity in O 2 /CO 2 . Subsequently, in the exothermic stage, the NCP and DT char combustions obey different mechanisms, in which the reaction orders are 1.65 and 1, respectively. According to the significant differences in variable activation energies obtained from the TG and the DSC data, the char reaction can be divided into a multi-step chemisorption oxidation stage and a one-step burning stage. Compared with TG method, DSC method is more suitable for describing the reactive characteristics of the multi-step stage. The results show that the char-O 2 /CO 2 chemisorption partially shares common active sites with a complicated multi-step mechanism. The trends of variable activation energies with char conversion ratio at different O 2 concentration in O 2 /CO 2 are similar. The activation energy is not significantly affected by CO 2 , and is about 178 ± 11 kJ/mol. The intrinsic reaction mechanisms of DT char combustion in O 2 /CO 2 and O 2 /N 2 have no fundamental difference; however, the NCP char combustion is affected by both CO 2 and oxygen partial pressure.

In this paper, a systematic method to construct the radiative energy signal (RES) is proposed based on an image-processing-based combustion monitoring and control system with 16 high-temperature flame image detectors with CCD cameras mounted in a 300 MWe power generation plant. In this method, the gray value in GSU (Grey-Scale Unit) in every image is first transformed to a raw RES with the same unit and scale for the power output, and then a final RES is obtained after compensation for the load. RES signals thus calculated were found to be higher or lower than the measured power output indicating deviation of the fuel feed rate from optimal values leading to undesirable combustion conditions in the plant. As the load either increases or decreases in a large range, the RES values consistently and even synchronously varied based on increased or decreased loads. RES is successfully used to optimize the heat value signals of the power plants. The results show that RES constructed by the proposed method reveals the fluctuating level of energy in the boiler and may be used to monitor and control the operation of the system.

To improve the efficiency of full-spectrum correlated-k-distribution (FSCK), a new method FSCK-RSM has been proposed based on response surface methodology (RSM) in this paper. The k-distributions of FSCK was used to fit the response surface model based on radial basis function and the radiative calculation efficiency was improved by avoiding multiple computations and interpolation in the FSCK-RSM. The thermal radiation heat transfer of five combustion gases (H2O, CO2, CO, C2H2 and C2H4) in a one-dimensional layer was investigated and the radiative sources calculated by the LBL, SNB, FSCK and FSCK-RSM methods were given at different distributions of temperature and gas concentration. The results showed that the needed amount of input data was reduced by 677 times using FSCK-RSM comparing to the FSCK and the maximum of the average normalized deviation for FSCK-RSM was 2.46% in the non-isothermal homogeneous medium. The model was finally used for radiation reabsorption calculations in planar C2H4/O2/N2/CO2 flames with full coupling to heat transfer and multi-species chemistry. The computational time using the FSCK-RSM was found to be at most half of that using the FSCK method. This FSCK-RSM model was an effective method for addressing the radiation problems that occur in combustion systems.