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Volatile state mathematical models for quantifying the chemical components in volatile biomass pyrolysis products were developed. The component mass yield Yi rate depends linearly on its pseudo kinetic constant and the remaining mass yield. The mass fraction rate of each component was modeled from the derivation of its mass yield rate equation. A new mathematical model equation was successfully developed. The involved variables are: biomass number, temperature, heating rate, pre-exponential factor, and pseudo activation energy related to each component. The component mass fraction yi and the mass yield were predicted using this model within a temperature range. Available experimental pyrolysis data for beechwood and rice husk biomass were used to confirm the developed model. The volatile products were separated into bio-pyrolysis gas (BPG) and a bio-pyrolysis oil (BPO). Five components in the BPG and forty in the BPO were quantified. The pseudo activation energy for each pseudo chemical reaction for a specific component was modeled as a polynomial function of temperature. The component mass fraction and yield are quantifiable using this developed mathematical model equation within a temperature range. The predicted component mass fractions and yields agreed excellently with the available experimental data.

Currently, the fuel oil for transportation and industry is produced mostly from fossil fuels. Because fossil fuels are a limited resource, biomass could be an alternative resource. Empty fruit bunch (EFB) is biomass waste from fresh fruit bunch processing in palm oil mills. EFB can be converted to bio-crude oil through pyrolysis at temperatures from 400 to 600 °C. The quality of bio-crude oil must be upgraded due to its high oxygen content. Esterification of bio-crude oil potentially improves the quality of bio-crude oil by using zeolite as catalyst. The purpose of this research was to investigate the properties of Bayah natural zeolites for upgrading the quality of bio-crude oil from EFB pyrolysis. Bayah natural zeolite was activated using various NaOH concentrations. Characterization of the natural zeolites was performed by using X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray (SEM-EDX), and nitrogen physisorption. The optimum ratio of Si/Al of the modified Bayah natural zeolites was 3.91. The surface area of the parent was initially 19 m2/g and increased significantly to 150 m2/g after treatment with 0.4 M NaOH solution. The application of the activated zeolites for bio-crude oil esterification successfully decreased the total acid number.

One potential utilization of dragon fruit skin is to produce bioactive materials as natural antioxidants and colorants for the food industry by extraction and spray drying. This study investigated the quality (total phenolic compounds/TPC, betacyanin and betaxanthin contents, and antioxidant activity) of the extracts and spray-dried products, and the quantity (powder yield) obtained by the use of different types and amounts of spray drying agents. Two drying agents were introduced during spray drying, i.e. maltodextrin and whey protein isolate (WPI). The result showed that a lower extraction solvent to solid ratio may result in a lower yield of TPC, betacyanin and betaxanthin contents, and also in antioxidant activity of the dragon fruit skin extract. In addition, maltodextrin and WPI were found to be able to significantly increase the yield from spray drying. The highest yield (72.7 ± 8.4%) was obtained with the use of 40% maltodextrin as drying agent, while the control yielded 9.5 ± 1.8%. Furthermore, it was found that the spray-dried product could recover more than 90% of the TPC and betacyanin in the extracts, which indicates that spray drying may be suitable for heat-sensitive materials.

Cassava is an important crop for tropical countries such as Nigeria, Brazil, Thailand, and Indonesia. The potential utilization of cassava in the food industry can be enhanced by processing cassava into fermented cassava flour (fercaf), which has been shown to have a neutral color and aroma as well as low cyanogenic content. The use of specific microbial starter in the cassava chip fermentation for fercaf production will direct the fermentation process, maintaining a high quality of the produced flour. Thereby, the availability of an easy-to-use microbial starter is important for the production of fermented cassava flour. The aim of this study was to evaluate vacuum drying methods in the preparation of microbial starter for fermented cassava flour production. In particular, the effects of carrier media, drying and storage temperature on cell viability in dry starter were tested. The results showed that different methods should be applied to different microbial species. Bacillus subtilis and Aspergillus Oryza should be prepared using fercaf as the carrier media at a drying temperature of 55 °C, whereas Lactobacillus plantarum starter should be prepared using skim milk as the carrier media at a drying temperatur of 40°C. Apart from B. subtilis, the starters should be stored in a refrigerator.

Solid fuel combustion is always preceded by chemical decomposition. This process is largely determined by the flow structure and affected by the geometry and operating conditions of the combustion chamber. This study aimed to investigate the effect of relative axial inlet diameter (Dai//Dbc) on the flow structure in the proposed cyclone burner. The flow structure was determined with the standard k-e turbulent model using the Ansys-Fluent software. From the simulation results it was concluded that with all the axial inlet diameters used an integrated vortex formed in the center of the burner cylinder. The integrated vortex consisted of two vortices, namely a primary vortex and a secondary vortex. The primary vortex penetrated from the furnace box to the burner cylinder, while the secondary vortex was formed in the burner cylinder itself. There were two integration patterns from the primary vortex and the secondary vortex, namely a summation pattern and a multilayer pattern. The presence of a vortex in the center of the burner cylinder is allegedly responsible for an increase in the degree of mixing and pressure drop in that zone. The flow structure induced from the proposed burner had high symmetricity and was largely determined by the burner's axial inlet diameter.

The stability of reactor operation for catalytic oxidation of lean CH4 has been investigated through modeling and simulation, particularly the influence of switching time and heat extraction on reverse flow reactor (RFR) performance. A mathematical model of the RFR was developed, based on one-dimensional pseudo-homogeneous model for mass and heat balances, incorporating heat loss through the reactor wall. The configuration of the RFR consisted of inert-catalyst-inert, with or without heat extraction that makes it possible to store the energy released by the exothermic reaction of CH4 oxidation. The objective of this study was to investigate the dynamic behavior of the RFR for lean methane oxidation and to find the optimum condition by exploring a stability analysis of the simple reactor. The optimum criteria were defined in terms of CH4 conversion, CH4 slip, and heat accumulation in the RFR. At a switching time of 100 s, the CH4 conversion reached the maximum value, while the CH4 slip attained its minimum value. The RFR could operate autothermally with positive heat accumulation, i.e. 0.02 J/s. The stability of the RFR in terms of heat accumulation was achieved at a switching time of 100 s.

As a major utility system in industry, boilers consume a large portion of the total energy and costs. Significant reduction of boiler cost operation can be gained through improvements in efficiency. In accomplishing such a goal, an adequate dynamic model that comprehensively reflects boiler characteristics is required. This paper outlines the idea of developing a mathematical model of a water-tube industrial boiler based on first principles guided by the bond graph method in its derivation. The model describes the temperature dynamics of the boiler subsystems such as economizer, steam drum, desuperheater, and superheater. The mathematical model was examined using industrial boiler performance test data.It can be used to build a boiler simulator or help operators run a boiler effectively.

More general correlations between pressure drop and gas-solid flow variables are developed from the present experimental data. The correlation was modeled for a pneumatic conveying system in a vertical pipe. The transition boundary between dense and dilute regimes is constructed from the pressure drop correlations. The gas-solid particle flow variables are quantified by the gas Reynolds ( N ref ) and the solid Froude ( F rp ) numbers. The dense flow regime is indicated by the decrease of the pressure drop with the increase of the gas Reynolds number. In contrary, the dilute regime exhibits the increase of the pressure drop with the gas Reynolds number. The proposed correlations were built at the range of gas Reynolds number f from 360 to 500 and solid Froude number from 0,01 to 0,02.

In a packed bed catalytic reactor, the fluid flow phenomena are very complicated because the fluid and solid particle interactions dissipate the energy. The governing equations were developed in the forms of specific models. The shear factor model was introduced in the momentum equation for covering the effect of flow and solid interactions in porous media. A two dimensional numerical solution for this kind of flow has been constructed using the finite volume method. The porous media porosity was treated as non-uniform distribution in the radial direction. Experimentally, the axial velocity profiles produce the trend of having global maximum and minimum peaks at distance very close to the wall. This trend is also accurately picked up by the numerical result. A more comprehensive shear factor formulation results a better velocity prediction than other correlations do. Our derivation on the presence of porous media leads to an additional viscosity term. The effect of this additional viscosity term was investigated numerically. It is found that the additional viscosity term improves the velocity prediction for the case of higher ratio between tube and particle diameters

In this study, the homogeneity of the continuum model of a fixed bed reactor operated in steady state and unsteady state systems for lean CH4 oxidation is investigated. The steady-state fixed bed reactor system was operated under once-through direction, while the unsteady-state fixed bed reactor system was operated under flow reversal. The governing equations consisting of mass and energy balances were solved using the FlexPDE software package, version 6. The model selection is indispensable for an effective calculation since the simulation of a reverse flow reactor is time-consuming. The homogeneous and heterogeneous models for steady state operation gave similar conversions and temperature profiles, with a deviation of 0.12 to 0.14%. For reverse flow operation, the deviations of the continuum models of thepseudo-homogeneous and heterogeneous models were in the range of 25-65%. It is suggested that pseudo-homogeneous models can be applied to steady state systems, whereas heterogeneous models have to be applied to unsteady state systems.

The pyrolysis of coal and biomass is generally repo rted as the mass yield of released chemicals at various temperatures , pressures, heating rates and coal or biomass type. In this work, a new coal-biom ass type number, NCT , is introduced. This number is constructed from the mas s fractions of carbon, hydrogen, and oxygen in the ultimate analysis. This number is unique for each coal or biomass type. For 179 different species of coal and biomass from the literature, the volatile matter mass yield can be e xpressed by the second order polynomial function ln( NCT ). This unique correlation allows the effects of th e temperature and heating rate on the volatile yield YVY for coal and biomass to be empirically correlated as well. The correlation for the mass fraction of each chemical component in the released volatile matter correlation is obtained from the YVY correlation. The weight factor for some of the comp onents is constant for the variation of NCT , but not for others. The resulted volatile matter and yield correlations are limited to atmospheric pressure, v ery small particles (less than 0.212 mm) and interpreted for wire-mesh pyrolysis r eactor conditions and a nitrogen gas environment.

This paper describes akinetic study for the determination of the kinetic parameters of lean methane emission oxidation over Pt/γ-Al2O3 in a dedicated laboratory scale fixed bed reactor. A model ofthemechanistic reaction kinetic parameters has been developed. The reaction rate model was determined using therate-limiting step method, which was integrated and optimized to find the most suitable model and parameters. Based on this study, the Langmuir-Hinshelwood reaction rate model with the best correlationis the one where the rate-limiting step is thesurface reaction between methane and one adsorbed oxygen atom. The pre-exponential factor and activation energy were 9.19 x 105 and 92.04 kJ/mol, while the methane and oxygen adsorption entropy and enthalpy were "“17.46 J/mol.K, "“2739.36 J/mol,"“16.34 J/mol.K, and "“6157.09 J/mol, respectively.