BACKGROUND AND OBJECTIVES: Agriculture significantly contributes to global economies, yet it concurrently generates waste in the form of crop residues. Conventional waste disposal methods, such as open burning, contribute to atmospheric particulate emissions, impacting air quality regionally and potentially globally. Exposure to these pollutants poses substantial risks to human health, including respiratory illnesses, cardiovascular diseases, and premature mortality. This study aims to assess the environmental implications of Biomass waste combustion in Yogyakarta, Indonesia. Additionally, the study aims to investigate potential enhancements in Biomass burning practices through experimental campaigns conducted in both open and closed burning conditions.METHODS: The study evaluates Yogyakarta's regional air quality using data from the Meteorology, Climatology, and Geophysical Agency for the period spanning from 2020 to 2022. Emission factors from open and closed burning practices are assessed using an experimental furnace equipped with real-time combustion parameters monitoring, including temperature, particulate matter concentration, and oxygen and carbon dioxide levels. The openburning experiments involve various combustion conditions for bagasse, leaf litter, and rice straw, encompassing variations in ignition location, initial mass, and air supply methods. Closed burning experiments explore variations in reloading frequency, air-fuel ratio, and air staging.FINDINGS: Yogyakarta's air quality assessment involves comparing rice harvest trends with atmospheric particulate matter concentrations during 2020-2022. Open burning practices in Yogyakarta exhibit a correlation with heightened rainfall, which in turn leads to higher emissions from April to August due to reduced rain frequency. Experimental campaigns have revealed that open burning practices result in a significant amount of emissions, ranging from 3 to 29 grams of particulate matter per kilogram of Biomass.. Meanwhile, the utilization of closed combustion systems has been demonstrated to decrease the emission factor within the range of 0.37 to 1.98 grams of particulate matter per kilogram of Biomass. This highlights the importance of operating conditions altering particulate emissions. Moreover, the emission reduction by factor nine, emphasizing the efficacy of controlled combustion techniques in comparison to open burning methods, in mitigating particulate emissions.CONCLUSION: The study identifies that greater initial Biomass mass, mid-ignition, and natural airflow contribute to lower emissions in open burning practices. o achieve optimal closed combustion conditions, it is recommended to reload Biomass more frequently with100 percent excess air allocation, distributing 30 percent to primary air and 70 percent to secondary air. These findings not only propose better practices for disposing of agricultural waste and minimizing air pollution but also emphasize the potential of utilizing Biomass waste for energy conversion.

Full Text [PDF 1025KB] Increasing energy cost and reduction of fossil fuel resources have been resulted in increasing demand of renewable energy, such as micro Biomass particles in small scale Stirling engines to generate combined heat and power. In such Stirling engines, Biomass particles are burnt in external combustion chamber and then, the generated heat is transferred to the working fluid of the engine cycle. Therefore, combustion of fine particle plays basic role in operation and effectiveness of these Stirling engines. Simulation of combustion chambers of those engines using computational fluid dynamics, as a first step of engine design, can reveal more insight to optimization process. In this study, combustion chamber of 55 kW combined heat and power Stirling engine has been simulated and the effects of some parameter have been investigated. The numerical results show good agreement with experiments. Increasing secondary air mass flow rate yields hotter flue gas and higher Stirling engine efficiency. The smaller particles yield to more evaporation and combustion rate of particles which cause to increase outlet temperature. Increasing particle injection velocity causes to decrease burning rate of particle, because some particles leave out the combustor before evaporation and burning.

Background and purpose: CO2 is the main cause of greenhouse effect. Previous studies have shown that CO2 in methane and coal flue gas can lead to microalgae growth. The aim of this research was to study the CO2 biofixation by Spirulina and injecting kerosene flue gas. Materials and methods: A photo bioreactor was fabricated in which kerosene flue gas and air were separately injected. The photo bioreactor was filled by growth medium without carbon source. Light source was four fluorescent lamps (10 Klux intensity) operated in continuous and intermittent modes. The concentration of CO2 was chosen in the range of 580 to 6000 ppm that was measured by NDIR CO2 detector. The initial concentration of algae was 20 mgL-1. The algal Biomass production was measured during the experiment. Results: The maximum production of algae by air and kerosene flue gas containing 5500 ppm CO2 using artificial intermittent light was 0. 07 and 0. 41 gL-1 d-1 and maximum concentrations of Biomass were 0. 25 and 1. 63 gL-1, respectively. CO2 biofixation rates were between 2. 27% and 4. 03% at different runs. Biomass productivity with intermittent light was 15% less than continuous light and it reached 1. 91 gL-1 with 5500 ppm CO2 using continuous light. Conclusion: In this study, the ability of a photo bioreactor was confirmed in the removal of CO2. Also, increase in CO2 contributes to increase in Biomass production.

A mathematical model has been investigated to predict the effect of hydrodynamic forces, especially thermophoretic forces on micro organic particles in counter-flow combustion in this research. Hydrodynamic forces change the velocity and concentration of evaporative organic particles moving toward the flame and they make a particle-free distance above the flame surface. Particle evaporation creates a thrust force that affects the velocity of the particles, which can be ignored compared to other hydrodynamic forces. Also, the temperature difference between the particles, the interaction of the particles on each other is neglected.The distance between the inlet nozzle and the flame surface is divided into four zones to investigate the dynamic behavior of particles in the flame front that in each case, the dynamic particles equations are written and the effect of thermophoretic force, weight force, drag force and buoyant force are analyzed on the particles and as a result, the velocity and concentration profiles of the particles are obtained in terms of distance from the flame front at different strain rates and with different particle diameters. The particles concentration of above the flame front increases with the balance of these forces, which the increasing the particles accumulation above the flame decreases the combustibility of particles in the flame front. Then, the length of the particle-free zone is extracted under the influence of different strain rates at different temperatures. As the flame surface approaches, the temperature gradient rises and the thermophoretic force increases. Accordingly, heavier particles accumulate closer to the flame surface.

In this paper, a thermochemical equilibrium model is used to predict the performance of a downdraft Biomass gasifier. Numerical results are shown to be in good agreement with those of the experiments. Different Biomass materials are tested using the model, and forest residual is shown to be the most energetic one. For this material, the gasification temperature, syngas composition and calorific value are calculated. The effects of moisture content, air/fuel ratio, air inlet temperature and steam/fuel ratio are also investigated. The air inlet temperature is found to be the only way to increase syngas calorific value and cold gas efficiency. The steam/fuel ratio, on the other hand, plays a key role in controlling the gasification temperature and H2/CO ratio.

BACKGROUND AND OBJECTIVES: The needs of fuel pellets from varied feed stocks have opened up opportunities and challenges for pellets production from non-woody Biomass. Wastes of plastic recycling and wood sawing contained a high potential for energy source and suited for pelletizing as a solid fuel. METHODS: The characteristics and combustion kinetics of fuel pellets made using a mixture of waste of polyethylene terephthalate and Biomass (Tectona grandis Linn. f) with a polyethylene terephthalate to Biomass ratio of 9: 1. The investigation covered physico-chemical properties and their functional group analysis, heavy metal concentration and ionic leachability testing, and ash analysis. In this context, thermogravimetric analysis was used in an atmosphere of oxygen gas, over a temperature range of 50-800 oC and at different heating rates. The work ends with discussion of the kinetics study via three comparative evaluations and the feasibility of fuel pellets for energy utilization. FINDINGS: Pelletizing with this ratio (9: 1) was present the durability of PET/Biomass pellets, a uniform dimension, ease handling, storage, and transportation common as woody pellets. Some technical challenges such as low moisture content and high volatile matter content were feedstock dependent. The major characteristics were a combination of those from both the constituent materials. Functional groups of the pellets were contributed by terephthalate and lignocellulose. The addition of a small amount of Biomass in pellets could improve their thermal decomposition behavior. The properties of the polyethylene terephthalate/Biomass pellets indicated that were fit for combustion with a high heating value equal to 19. 20 MJ/kg. Heavy metals and ionic contaminants were below the maximum limits of the standards because of the cleanliness of the raw materials. However, the minor effects of earth materials and a caustic soda detergent were resulted in the alteration of residue chemicals. The pellets had lower ignition, devolatilization, and burnout temperatures than the original polyethylene terephthalate waste,likewise, the peak and burnout temperatures shifted to a lower zone. The activation energy values obtained using the Kissinger-Akahira-Sunose, Ozawa-Flynn-Wall, and Starink models were similar and in the range 142–, 146 kJ/mol. CONCLUSION: These findings may provide crucial information on fuel pellets from blended polyethylene terephthalate/Biomass to assist the design and operation of a co-combustion system with traditional solid fuels. Such modifications of fuel pellets suggest the possibility of operating in large-scale furnace applications and can further be upgraded to other fuels production via modern bioenergy conversion processes.

The aim of this study was to determine the amount of carbon dioxide uptake and Biomass production in a photo bioreactor containing Spirulina microalgae as growth medium by injecting the products of natural gas combustion. A photo bioreactor was fabricated and combustion products of natural gas as well as air were injected by separate diffusers. The photo bioreactor was filled by growth medium without carbon source. In the control and test reactors, carbon dioxide was supplied by air and flue gas, respectively. Light source was natural and artificial. Artificial light source was four fluorescent lamps having 10 Klux intensity, which were operated in continuous and intermittent modes. The concentration of carbon dioxide entering in the test reactor was chosen in the range of 580 to 5000 ppm. The concentration of carbon dioxide in the inlet and outlet gas of the reactor was measured by a carbon dioxide detector equipped with NDIR. The algal Biomass production and also changes in pH were measured. The flue gas was used as such without any scrubbing or desulfurization. The maximum production of algae using air and combustion products of natural gas having 4100 and 3300 ppm carbon dioxide using artificial intermittent light was 0.07 and 0.2 gL-1 d-1, respectively. Moreover, the maximum concentration of Biomass was 0.25 and 1.04 gL-1, respectively. Carbon dioxide biofixation rate was 2.5 and 3.3% in the 3300 and 4100 ppm carbon dioxide runs. Natural gas combustion products can be injected in the photo bioreactor directly and without prior treatment, and it is possible to remove carbon dioxide and produce algae. Biomass productivity with intermittent light was 35% less than continuous light. With the increasing concentration of carbon dioxide in the combustion gas, algal Biomass production increased.

It seems that chronic airway diseases is high among women of this province, which might be due to biome fuel and wood burning for cooking and heating. This case control study was performed in over 40 years old women to evaluate the risk of smoking and Biomass combustion on chronic bronchitis. The case group consisted of 100 patient's whit chronic bronchitis and the control group consisted of 100 patients from surgical ward of the hospital. A questionnaire about type of stove for cooking, heating and baking was filled by each subject. Significant correlation's were found between smoking (P<0.01), tobacco pipe (P<0.01), baking in home (P<0.01), wood burning for heating (P<0.01), wood burning for cooking (P<0.001), oil for cooking (P<0.001), wood burning for baking (P<0.001) and chronic bronchitis. Wood and other Biomass fuel for cooking, heating and baking are important cause of chronic bronchitis in women in Chahar-Mahal and Bakhtiari region and replacement of wood and oil by a better alternative, like gas, is recommended