Shaharin Anwar Sulaiman

Modeling and simulation study of downdraft gasifier using oil-palm fronds

Gasification of biomass provides clean and combustible gas with sufficient energy, which can be used for electricity generation, engine applications etc. However, successful design and operation of gasifiers are not simple. There are no neat rules as the thermodynamics of gasifier operation are not well understood. In this paper, a preliminary study of the operation and performance of downdraft biomass gasifier using oil palm fronds (OPF) is done. The performance study is partially carried out using ASPEN PLUS process simulator software for modeling and simulating the various zones of the gasification process (drying, pyrolysis, oxidation and reduction). As ASPEN PLUS does not have a built in gasifier model, a combination of the various reactors of the simulator are used to model the gasification processes. This model is used to predict the producer gas composition for different operating temperatures, pressure and air-fuel ratio. In addition a primary experiment is carried out to determine the feasibility of OPF as a gasification feedstock. From the simulation study it is shown that higher mass fraction of CO and CH4 can be obtained at lower Air-Fuel ratio, and lower pressure (below 5bar). The mass fraction of CO increases sharply with increase in the oxidation zone temperature, for the range 500–700°C.

Effect of pre-coat solution temperature on fluidized bed urea coatings

Abstract In this study, coating properties of the native cassava starch were improved by reacting it with urea and di-sodium tetraborate. The FTIR spectroscopy was used to study the possible reaction mechanism of the coating formulation. The prepared starch dispersions were used to coat 3·45 mm urea granules in a swirling fluidised bed reactor. An in-house built fluidised bed with an intermittent top spraying facility was used to coat the urea beds fluidised above their minimum level of fluidisation. The pre-coat solution temperature was varied from 50 to 80°C and the corresponding coated urea samples were further characterised for their surface morphology, coating hardness and nitrogen release time. The SEM images revealed that the surface of the coated urea was harder, denser and smoother as compared to the uncoated urea. Significant improvements in mechanical parameters of coated urea were seen with an increase in solution temperature and mass of the di-sodium tetraborate. The overall nutrients release time of the coated urea in water was increased from 63·33 to 209 s. The surface hardness and coating thickness of coated urea was also increased with an increase in pre-coat solution temperature and di-sodium tetraborate mass in the coating composition.

Experimental Study of Airless Spray Jet Breakup at Elevated Temperature and Pressure

The presented research work was focused onto the understanding of the jet behavior of the sprays of heated water during the low pressure atomization process. This task was accomplished using an in-house built intermittently forced liquid spraying system capable of lowering the liquid viscosity and surface tension to a desired value and then atomizing it into a full cone spray patterns in the ambient air surrounding. Using a high speed camera, the jet breakup dynamics were visualized as a function of system input parameters. The analysis of the grabbed images confirmed the strong influence of these processing parameters on full cone spray characteristics. It was also predicted that heated liquids generate a dispersed spray pattern by utilizing the partial evaporation of the spraying medium that is the induction of thermal energy enhances the jet disintegration ability. The spray cone width and angle did not vary significantly whereas the Weber and Reynolds numbers along with other nozzle flow parameters showed an appreciable response to the load pressure and temperature at early stages of water injection. The ultimate objective of the work was to understand and control the airless spray jet breakup mechanism under reduced load pressure and high water temperature.

Study of Indoor Air Quality in Academic Buildings of a University

ndoor Air Quality in educational environment is very important as it could interfere with the learning process. In this paper, the indoor air quality of selected lecture rooms of different sizes in an academic building was studied, involving measurements of indoor temperature, relative humidity, CO2 level and dust particles. A mixed result was observed on the relative humidity in the rooms. The levels of dust particles were observed acceptable although recorded higher in the small lecture room as compared to the lecture theater. The CO2 content in the lecture theatre was found to be higher than that in the small lecture room, and also exceeded the maximum recommended level. Overall, the results suggested that the lecture theatre needs attention in the aspect of Indoor Air Quality.

Comparison Studies of Criado and Coats-Redfern Methods for Co-Gasification of Rubber Seed Shell with High Density Polyethylene Mixtures

In this present study, the gasification kinetics of rubber seed shell, high density polyethylene, and their mixtures (20/80 and 40/60 weight ratio of HDPE/RSS) are investigated using a non-isothermal thermogravimetric analysis (TGA) system at heating rate of 10 K/min in the temperature range of 323-1173 K. The argon gas is supplied at a flowrate of 100 ml/min and the steam is generated from superheater at 383 K. The steam is injected at flowrate of 300 μL/hour into the TGA system. The Criado and Coats-Redfern methods are used to investigate the reliability of the determined value of the activation energy, EA from the experimental data of TGA. The interaction of solid-phase components based on the mentioned experimental conditions is also studied.

Hydrodynamics of oil palm frond in a swirling fluidized bed dryer

This paper presents the hydrodynamics of chopped oil palm fronds (OPF) from cold flow experiments carried out in a swirling fluidized bed dryer (SFBD). The chopped OPF was 10 – 15 mm in size and falls in between Geldart type B and D. The OPF which consisted of leaves and petiole (stem) were first separated before studied individually due to their different physical characteristics. 2 bed loadings of 120g and 140g were investigated for bed pressure drop, (ΔPb), minimum fluidization velocity (Umf) and minimum swirling velocity (Ums) while regimes of operation were closely observed. The experiments yield that the OPF leaves and petiole have distinct hydrodynamic behavior due to their different bulk densities and voidage, hence suggesting drying should also be conducted separately unlike the current industrial practice. The leaves have lower Umf and Ums compared to the petiole and thus swirling motion was initiated earlier in SFBD when operating with leaves. Both samples however, have limited operating velocities due to elutriation. In conclusion, the SFBD was found to fluidize the chopped OPF well while providing good solid-gas contact which is highly desired for drying.

Study on Indoor Air Quality of a Small Office in a Tropical Country

Recently, the importance of appropriate Indoor Air Quality (IAQ) attracts interests in health research area. The study of IAQ is important in office. Long term period exposure to poor IAQ level, can lead to discomfort and uneasy feeling and thus may affect productivity and quality of life. The objective of this work is to study the IAQ level in a small lecturer office of an educational building in Malaysia. Throughout this research, the IAQ of a selected lecturer office room was studied. The study involved measurements of indoor air temperature, relative humidity, and CO2 level. From the study, it was found that the level of CO2 temperature and humidity were always within the range of recommended by ASHRAE.

Operating Characteristics of Gasifier Cookstove Using Different Biomass Materials

Biomass energy technology such as gasifier is increasingly receiving attention as a promising renewable energy source because of the ever rising costs of fossils fuels especially diesel and kerosene. Gaseous products of gasifier based cookstove are relatively clean and environmental friendly than direct combustion cookstove. The objective of this workwas to characterize the basic operating properties of a gasifier-based biomass cookstove using different types of biomass fuels. The main characteristics evaluated were the efficiencyof the stove. The biomass considered were oil palm fronds, dry leaves and pressed sugarcane. The efficiency of the stove was tested using water boiling tests.Other characteristics such as its ignition duration and the time required to boil 2.5 kg of water were also observed. The performance of each fuel was studied by analyzing the parameters involved during water boiling tests. It was found that oil palm frond has the highest thermal efficiency among all the fuels tested.

Study of primary atomisation phenomenon of modified starch solution stream at elevated temperature

Abstract The objective of the work was to study the primary atomisation phenomenon of the starch–urea–borate complex solutions at elevated temperature. Firstly, the dynamic viscosity and surface tension of the solutions were studied as a function of temperature and applied shear rate. Secondly, using a high-speed camera (Phantom v9·1) and phase Doppler anemometry, the jet breakup dynamics, Sauter mean diameter and droplet velocity vectors were studied. A shear-thinning behaviour followed by shear thickening was observed for all solution compositions. The surface tension was decreased concomitantly with an increase in solution temperature. However, an increasing trend in a spray cone angle was noticed when solution temperature was elevated up to 80°C. The phase Doppler anemometry studies revealed that at 80°C solution temperature and 1·5 bar load pressure, the spray droplets start getting uniform sizes and move in random directions at 120 cm downstream of the nozzle exit.

Kinetic Analysis on Catalytic Co-Gasification of Rubber Seed Shell and High Density Polyethylene Mixtures

In this paper, the catalytic co-gasification of rubber seed shell and high density polyethylene mixtures (0.2:0.8 weight ratio of HDPE:RSS) are investigated using a non-isothermal thermogravimetric analysis (TGA) system in a range of heating rates of 10, 20, 30 and 50 K/min within the temperature range of 323-1173 K. The argon gas is supplied at a flowrate of 100 ml/min and the steam is generated from superheater at 383 K. The steam is injected at flowrate of 300 μL/hour into the TGA system. A commercial nickel powder is used as the catalyst for the gasification process. The thermal decomposition behavior and synergistic effect of the HDPE/RSS mixture are investigated. The activation energy, EA and pre-exponential factor, A are determined based on one step integral method.