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A microwave thermogravimetric analyzer was used to measure the characteristics of a mixture of palm oil solid waste (fiber, shell, and empty fruit bunch) and polyethylene terephthalate (PET). In the study, the range of palm oil solid waste composition ratios to PET used was 100:0, 75:25, 50:50, 25:75, and 0:100 (by weight). The study included the influence of the quality of raw material on the heating process. The mixture of palm oil solid waste (fiber, shell, and empty fruit bunch) and PET proved to impact the heating rate, mass-loss rate, and energy consumption. Based on the observation, empty fruit bunch-PET mixture had the highest heating rate (average 1.5039°C/s) than shell (average 0.6058°C/s), and fiber (0.9119°C/s) and also had the highest mass-loss rate (average 0.0253 g/s). The highest biomass (shell, empty fruit bunch, and fiber) and PET composition ratio give the highest rate of heating rate (average 1.8264°C/s) and mass-loss rate (average 0.02875 g/s). In addition, the increasing ratio of fixed carbon and material density will impact the increasing heating rate and mass-loss rate and decrease energy consumption. Therefore, fixed carbon and material gaps significantly affect the heating rate. [ABSTRACT FROM AUTHOR]

Torrefaction process is one of the solutions to produce solid fuel from a cocoa pod shell (CPS). Fuel characteristics of CPS changed after torrefaction. Effects of torrefaction temperature and holding time on physical, thermal, and chemical properties of CPS were investigated in this study. The experiments were conducted in a tubular torrefaction reactor. Three different torrefaction temperatures of 200, 250, and 300 °C and four holding times of 0, 30, 60, and 90 min were considered in this investigation. It was found that the color of CPS changed from light brown to black due to the increasing content of fixed carbon and depend on the torrefaction temperature and the holding time. The decrease in the grayscale value of the torrefied CPS represented an increase in HHV. Fixed carbon content and - higher heating value (HHV) of the torrefied CPS increased up to 17.5% and 41.3% compared to the raw CPS, while the volatile matter decreased up to 19.4%. The O/C and H/C atomic ratio decreased from 0.79 and 1.68 to 0.37 and 1.01, respectively, which corresponded to the increase of carbon content and decrease of oxygen and hydrogen contents. The properties of severe torrefaction CPS resembled between lignite and peat. The grindability and hydrophobicity of CPS was improved. The CPS based biochar should be used as a substitute for solid fuel that has the same characteristic to reduce the unfavorable effects of its potassium content. [ABSTRACT FROM AUTHOR]

Experimental work to figure out the effect of tuyer inclination angle on performance of small-scale downdraft gasifier fed by rice husk–sawdust blend was performed. Performance of the gasifier in terms of the temperature profile, fuel consumption rate, composition and heating value of producer gas, and cold gas efficiency (CGE) is evaluated. Air is injected at the location of 330 mm above the grate. Tuyer inclination angles observed are 0°, 30°, and 60°. Meanwhile, ratio of rice husk and sawdust is 1:1 by mass and equivalence ratio for gasification is 0.15 for each tuyer inclination angle. The result indicates that the use of inclined tuyer increases maximum temperature and volume fraction of CO and H2 in producer gas thus enhances higher heating value of producer gas. Maximum CGE of 76.29% is found with the use of horizontal tuyer. [ABSTRACT FROM AUTHOR]

Abstract Although several works on rice husk gasification have been reported, none of those works investigated and discussed the propagation front. In present work, rice husk gasification is conducted in a small-scale throat-less downdraft gasifier. The aim of the work is to investigate the effect of tuyer distance above the grate on the propagation front and performance of the gasifier. Rice husk gasification is performed at an equivalence ratio of 0.20 with variations in tuyer position above the grate of 120 mm, 190 mm, 260 mm, 330 mm, and 400 mm. The result shows that tuyer distance above the grate affects the propagation rate and the performance of the gasifier. The flame and bed propagation rates are nearly similar for the tuyer 400 mm above the grate. Meanwhile, a volume fraction of combustible gases CO, H 2 , and CH 4 improve as tuyer distance above the grate increases. Maximum values of 15.18% CO, 6.99% H 2 , and 0.99% CH 4 are obtained for the tuyer 400 mm above the grate. Maximum HHV of 3.21 MJ/Nm3 and thermal efficiency of 76.90% are also achieved for the tuyer 400 mm above the grate. Highlights • Rice husk gasification in small-scale downdraft gasifier with equivalence ratio of 0.2 • Investigation effect of tuyer distance above the grate on propagation and performance. • Tuyer distance above grate are 120 mm, 190 mm, 260 mm, 330 mm, and 400 mm. • Flame and bed propagation rates are nearly similar at tuyer 400 mm. • Maximum HHV and thermal efficiency are achieved at tuyer 400 mm above the grate. [ABSTRACT FROM AUTHOR]

In this work, pilot scale throat-less downdraft gasifier is fabricated and tested on rice husk and blend of rice husk-sawdust. The test aims to investigate effect of equivalence ratio on temperature profile, propagation front (flame propagation rate, bed movement rate, and effective propagation rate), and performance of the gasifier (composition of producer gas, heating value of producer gas, and thermal efficiency of the gasifier). Equivalence ratio investigated are 0.15, 0.20, and 0.25, while the blend ratio is 1:1 by mass. The results show that axial temperatures in the reactor surge faster with increasing equivalence ratio during the rice husk gasification and the blend gasification. Typically, flame propagation rate, bed movement rate, and effective propagation rate improve with rising equivalence ratio from 0.15 to 0.25. The best higher heating values and thermal efficiencies are obtained at equivalence ratio of 0.2 and 0.15 for the rice husk gasification and the blend gasification, respectively. [ABSTRACT FROM AUTHOR]

Downdraft gasifier is very attractive for biomass gasification due to its easy fabrication and operation, and also due to low tar content in producer gas. However, drawbacks such as grate blocking, channeling, and bridging are found in the downdraft gasifiers, typically for feedstock with low bulk density. Another disadvantage is the downdraft gasifiers only suitable for feedstock with low moisture content. The design of the gasifiers is an important parameter that affects their performance. Various works on design improvements have been done for enhancing the performance of the gasifiers. This paper aims to review small-scale downdraft gasifiers for biomass gasification which is focused on design improvements and their effect on the performance of the gasifiers. Many works from previous researchers have been studied and cited. The result shows that the design of the gasifiers is an important parameter in gasification, besides biomass feedstock characteristics and process parameters. [ABSTRACT FROM AUTHOR]

Counteracting emissions of particulate matter (PM) is an increasingly important goal in sustainable biomass combustion. This work includes a novel approach to investigate the PM emissions, originating from residual biomass combustion, at different combustion conditions in a lab-scale grate-fired furnace and includes in situ PM measurements by using on-line sensors. The interior furnace design allows installation of baffles to suppress the emissions by controlling the residence time. Moreover, the two-thermocouple method is used to measure the true gas temperature, and an on-line spatially resolved PM measurement method is developed to study the evolution of the PM concentration throughout the furnace for different experimental conditions thereby allowing accurate in-situ measurement of the PM reactivity. Experimental results and computational fluid dynamics (CFD) analyses are utilized in the current work to develop a kinetic model for reduction of particulate matter emissions in biomass combustion. The discrete particle model (DPM) is utilized in CFD analysis to improve the understanding of the particle temperature and residence time distribution which are difficult to quantify experimentally. By combining the experimental measurements of real soot formed during biomass combustion and information from the CFD analyses, a predictive kinetic model for PM10 reduction in biomass combustion is successfully developed. [ABSTRACT FROM AUTHOR]

• Physicochemical particle model for drying, devolatilization and combustion. • Highly accurate and stable model providing good agreement with experimental data. • Continuous profiles of temperature and biomass component during conversion. • Computationally efficient model easy to implement in CFD analysis. Development of an accurate and computational efficient biomass particle model to predict particle pyrolysis and combustion is the focus of this paper. Partial differential equations (PDEs) for heat and mass balance are transformed into a system of coupled ordinary differential equations (ODEs) with the use of orthogonal collocation as the particle discretization method. The orthogonal collocation method is incorporated with comprehensive physicochemical mechanisms to predict the behavior of biomass components during particle pyrolysis and combustion. Heat adsorption by evaporated gas and water movement by diffusion inside the biomass matrix are included in the present work, in parallel with the effect of Stefan flow on the heat and mass transfer rates at the particle surface. Abandoning the classical interface-based modelling approach, the present approach allows decoupling between biomass components and spatial resolution, and the prediction of continuous intra-particle profiles. The new particle model is proven to be accurate and stable through its high degree of agreement with simulation results for particle pyrolysis and combustion experiments using different particle moisture contents and geometrical shapes. The intra-particle temperature gradient, as well as particle mass and size evolution, can be predicted accurately, as validated against experimental data. It is shown that six collocation points provide satisfying resolution. The computational efficiency is confirmed by the short simulation time that was found to be approximately three orders of magnitude faster than mesh-based simulations. This implies that the current model can be used for computational fluid dynamic (CFD) analysis through implementation as sub-grid-scale models to design, for example, biomass furnaces. [ABSTRACT FROM AUTHOR]

This research aims to evaluate horizontal and vertical constrained rod casting (CRC) molds on hot tearing susceptibility (HTS) of Al-xCu casting alloys with 2.2, 3.6, 7.5, and 12.5 percent Cu. The hot tears on the casting product were observed using a macroscopic approach. In addition, the hot tearing susceptibility of each casting product prepared using these molds was evaluated using the HTS formula. The results show that the vertical CRC mold has a higher HTS value than the horizontal CRC mold. The rod length is a significant factor in causing hot tearing. Longer rods are more susceptible to hot tearing. The horizontal CRC mold provides a clearer effect of rod length and Cu composition on the average HTS value. In the vertical CRC mold, the effect of Cu composition on the average HTS value is less clear. Therefore, it is highly recommended to use horizontal CRC mold for HTS testing of aluminum casting alloys. [ABSTRACT FROM AUTHOR]

Due to their low mechanical strength, the limited applications of fused filament fabrication (FFF)-printed products eventually intrigued researchers to overcome this problem through several approaches. Powder addition reinforcement (PAR) has been recognized as the oldest among the proposed techniques. However, several studies have shown the drawbacks of this technique concerning the poor bond between the printed polymer matrix and powder filler, as well as the nozzle clogging that often occurs during the printing process. In this study, a novel powder addition method using equipment that enables powder delivery with a continuous and intermittent flow was conducted. A composite sample was prepared by printing polylactic acid (PLA) filament combined with iron oxide (Fe3O4) powder particles. The results showed that the printed PLA/Fe3O4 samples obtained from processing with intermittent particle flow had better quality compared to those processed by continuous particle flow. However, both the continuous and intermittent powder addition experienced a negative effect due to rapid cooling caused by air exposure during the printing process. Nonetheless, the novel technique proposed in this study could show the ability to avoid nozzle clogging that might occur during the printing of PLA/Fe3O4 composite samples. [ABSTRACT FROM AUTHOR]