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Sun drying method has been used for drying agricultural commodities for centuries worldwide. The sun drying can be performed either by direct drying of the product under sunlight or drying using a solar collector-based dryer. However, a problem arises during the rainy season when there are lack of sunlight for proper drying. The application of biomass waste-powered dryers is a potential sustainable technology to encounter the problem. The present work aims to evaluate the performance and sustainability indicator of the rice husk-powered dryer under natural and forced convection modes while drying chili. The performance of the dryer evaluated is energy and exergy efficiency, and specific energy consumption (SEC). Meanwhile, the sustainability indicators evaluated are the waste-to-energy ratio (WER) and sustainability index (SI). The results show the performance and the sustainability indicator of the dryer are better under forced convection mode than that under natural convection mode. Overall energy and exergy efficiencies of the dryer are 3.58% and 4.93% under natural convection mode and the values are 16.85% and 16.13%, under force convection mode. Whereas, the SEC of the dryer is 26602.91 kg of rice husk/kg of water vapour for natural convection mode and 6979.89423 kg of rice husk/kg of water vapour under force convection mode. Furthermore, the sustainability of the dryer is better under force convection than under natural convection mode. WER under forced convection mode is lower than WER under natural convection mode. This gives a higher sustainability index (SI) of the dryer when operated under forced convection. The SI of the dryer ranges from 1.42 under natural convection to 1.92 under forced convection mode.

In order to encounter the shortage of fossil fuel, many efforts have been performed by researchers worldwide to find out an alternative technologies of renewable energy conversion. Biomass gasification, one of many promising energy conversion technologies, becomes more attractive in recent years. The present work aims to investigate an effect of air tuyere-grate distance (i.e. 260, 330, 400 mm) and equivalence ratio (i.e. 0.15, 0.20, and 0.25) on thermal behavior of the small-scale downdraft gasifier fed by sawdust. The reactor has internal diameter of 300 mm and height of 725 mm (from grate to the top). The thermal behavior of the gasifier in terms of axial temperature of the reactor, volume fraction of carbon monoxide, hydrogen, methane and higher heating value of the producer gas, and also cold gas efficiency are observed and analyzed. The result indicates that tuyere position above the grate affects the performance of the gasifier. The maximum higher heating value of the producer gas and cold gas efficiency are found at optimum tuyere-grate distance of 330 mm and equivalence ratio of 2.0. The maximum higher heating value of the producer gas and cold gas efficiency are 2.84 MJ/Nm3 and 66.36%, correspondingly.

Limbah biomassa di Indonesia sangat berpotensi sebagai sumber energi kalor ruang pengering produk pertanian. Penelitian ini bertujuan untuk memanfaatkan limbah sekam padi menjadi sumber kalor untuk pengeringan produk pertanian serta mengetahui unjuk kerja ruang pengering dengan bahan bakar sekam padi. Penelitian diawali dengan pembuatan rancang bangun mesin pengering yang dilanjutkan dengan pengujian unjuk kerja. Mesin pengering memiliki komponen utama berupa tungku pembakaran, ruang pengering, blower, dan suction fan. Pengujian unjuk kerja mesin pengering dilakukan untuk pengeringan cabai. Tujuan penelitian adalah untuk mengetahui pengaruh mode aliran konveksi flue gas terhadap efisiensi dan konsumsi energi spesifik (SEC) mesin pengering. Hasil penelitian menunjukkan bahwa mesin pengering dapat beroperasi dengan baik. Efisiensi mesin pengering aliran konveksi paksa lebih tinggi dari efisiensi mesin pengering aliran konveksi alami dan sebaliknya SEC mesin pengering aliran paksa lebih rendah dari SEC mesin pengering aliran konveksi alami. Efisiensi mesin pengering mencapai 25,12% untuk aliran konveksi paksa dan 10,50% untuk aliran konveksi alami. Sedangkan SEC mesin pengering aliran konveksi paksa sebesar 198370,37 kJ/kg uap air dan 918171,42 kJ/kg uap air untuk aliran konveksi alami.

This research aims to determine the effect of velocity stack geometry on the performance of 150 cc-four stroke motorcycles. Three different velocity stacks, namely VS5, VS15, and VS25 were made from Polyethylene using the 3D printing technique, with significant differences in their fillet radius and diameter inlet. A flow bench test was conducted to ascertain the internal aerodynamic qualities of the engine. The dynamometer assessment was carried out to determine its effect on the output power, torque, and specific fuel consumption of the motorcycle. The results showed that the engine expressed better performance when VS5, VS15, and VS25 were used compared to when they were not utilized. The torque and power rose slightly while specific fuel consumption reduced, when the fillet radius of the velocity stack inlet increased.

A biomass waste producer gas has a good potential as renewable sources fuel of either spark ignition (SI) or compression ignition (CI) engine. Several biomass wastes have been utilised as a feedstock of gasification process to produce producer gas. High heating value and low tar content producer gas should be obtained in biomass gasification. The producer gas has to be cleaned up to remove tar when it is used for the engines. The present paper aims to review a thermo-chemical conversion of a biomass into a producer gas, tar removal method and utilisation of a producer gas as fuel of internal combustion engine. Many previous published works are studied, cited and summarised in the present work. The review indicates that performance of a gasifier is affected by gasifier design and operating parameters, i.e. feedstock properties and size, gasification medium, equivalence ratio and gasification temperature. Tar removal can be approached using primary or secondary technique. Modification of the intake system of either SI or CI engine is required when the engine is fuelled with a producer gas.

Producer gas dari gasifikasi biomassa telah banyak digunakan sebagai bahan bakar mesin pembakaran dalam serta bahan bakar kompor gas. Namun, selama ini producer gas baru dimanfatkan secara langsung tanpa adanya penyimpanan, seperti gas alam terkompresi. Dengan demikian, penelitian ini bertujuan untuk mengetahui potensi konversi sekam padi menjadi compressed producer gas (CPG) melalui proses gasifikasi dengan rungku gasifikasi model aliran kebawah. Riset dimulai dengan produksi CPG dan dilanjutkan dengan pengujian mampu nyala CPG langsung dari kompresor (tahap 1) dan dari tangki CPG 3 kg dan 12 kg (tahap 2). Selama pengujian, dilakukan pengambilan data berupa photo nyala api, temperatur nyala api, dan durasi nyala. Hasil penelitian menunjukkan bahwa CPG dapat dihasilkan dari gasifikasi sekam padi pada tekanan kompresi 6 bar. Untuk meningkatkan kandungan energi CPG, pada penelitian selanjutnya diperlukan optimasi proses purifikasi producer gas sebelum dilakukan kompresi ke dalam tabung.

The geometric of a wind turbine rotor is an important parameter in the development of a horizontal axis wind turbine (HAWT). Simulation can be used to determine the rotor’s optimum geometry for specific wind speeds. The present study describes the three-dimensional (3D) computational fluid dynamics (CFD) simulation of a modified small-scale NACA-4415 HAWT rotor in order to predict power output and coefficient, using Blade Element Momentum (BEM) based on Lifting Line Theory (LLT). Power output and coefficient were analysed at wind speeds of 3, 4, 5, 6, and 7 m/s. The results predict that maximum power output increases with increasing wind speed. The predicted minimum power output of 35.41 Watt was obtained at wind speed 3 m/s and Tip Speed Ratio (TSR) 4; the predicted maximum power output was achieved at wind speed 7 m/s and TSR 6. As in the case of power output, power coefficient also improved with rising wind speed, with a coefficient of 0.259 at wind speed 3 m/s and TSR 4 and a coefficient of 0.449 at wind speed 7 m/s and TSR 5. Given Indonesia’s typical wind speed of 4 to 5 m/s, this modified NACA-4415 rotor is predicted to generate between 92 and 255 Watts of power. The power output results show good agreement between simulation and experiment, with an R2 value of 0.93.

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.

Many efforts have been performed by researchers worldwide to find out alternative technologies for renewable energy conversion to encounter the shortage of fossil fuel. Biomass gasification, one of many promising energy conversion technologies, has become more attractive in recent years. The present work aims to investigate the effect of air tuyere-grate distance (i.e., 260, 330, and 400 mm) and equivalence ratio (i.e. 0.15, 0.20, and 0.25) on the thermal behaviour of the small-scale downdraft gasifier fed by sawdust. The reactor has an internal diameter of 300 mm and a height of 725 mm (from the grate to the top). The axial temperature profile of the reactor, the volume fraction of carbon monoxide, hydrogen, and methane, the higher heating value of the producer gas, and cold gas efficiency are observed and analysed. The results indicate that the tuyere position above the grate affects the performance of the gasifier. The maximum higher heating value of the producer gas (HHVg) and the maximum cold gas efficiency (CGE) are found at an optimum tuyere-grate distance of 330 mm and an equivalence ratio of 2.0. The maximum values of HHVg and CGE are 2.84 MJ/Nm³ and 66.36%, respectively. [ABSTRACT FROM AUTHOR]

Increasing attention on the use of biomass derived syngas as internal combustion engine fuel, impacts on rising the demand of the scrubber for tar removal of the syngas. Wet scrubber is been used widely for this purpose. However, the liquid adsorbent containing tar may harmful when exposes to the environment. Thus to encounter the problem, the present work proposes the use of dry scrubber with zeolite as an adsorbent. The work aims to develop a simple and low cost zeolite scrubber and investigate and effect of zeolite size on performance of the scrubber for tar removal of syngas from biomass gasification. The result shows that zeolite size is proportional to specific area, heat transfer rate, and scrubber's effectiveness. The highest scrubber's effectiveness of 0.25 is obtained for the smallest zeolite size, i.e. 30 mm. [ABSTRACT FROM AUTHOR]

A biomass waste producer gas has a good potential as renewable sources fuel of either spark ignition (SI) or compression ignition (CI) engine. Several biomass wastes have been utilised as a feedstock of gasification process to produce producer gas. High heating value and low tar content producer gas should be obtained in biomass gasification. The producer gas has to be cleaned up to remove tar when it is used for the engines. The present paper aims to review a thermo-chemical conversion of a biomass into a producer gas, tar removal method and utilisation of a producer gas as fuel of internal combustion engine. Many previous published works are studied, cited and summarised in the present work. The review indicates that performance of a gasifier is affected by gasifier design and operating parameters, i.e. feedstock properties and size, gasification medium, equivalence ratio and gasification temperature. Tar removal can be approached using primary or secondary technique. Modification of the intake system of either SI or CI engine is required when the engine is fuelled with a producer gas. [ABSTRACT FROM AUTHOR]

The aim of the present work is to investigate an effect of primary air draft and flow rate on thermal performance and CO/CO2 emission of the domestic stove fed with the briquette of coconut shell. The work is conducted by following the simplified water boiling test method. Firstly, the stove is tested under natural draft mode (ND). Secondly, the stove is run under force draft mode at two different air flow rates, such that 0.013 m3/s (FD 1) and 0.020 m3/s (FD 2). In the present work, temperatures of water, flame, and stove are measured. Thermal performance of the stove in terms of fuel consumption rates (FCR), firepower (P), heating rates (Ew), thermal efficiency (ηT), and specific useful energy (SUE) is calculated and analyzed. CO/CO2 in flue gas is also measured and analyzed. The result indicates that air flow rate affects the thermal performance and CO/CO2 emission of the stove. Increasing air flow rate enhances the FCR, P, Ew, ηT, and SUE. On the other hand, increasing air flow rate reduces CO/CO2 in flue gas. The highest values of FCR, P, Ew, ηT, and SUE are obtained at the higher air flow rate. The values are 1.43 kg/h, 8.024 kW, 0.294 kW, 3.670%, and 741.975 kJ/kg, correspondingly. Meanwhile, the lowest CO/CO2 of 0.009 is observed at the higher air flow rate. [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]

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]