Mohd Rosdzimin Abdul Rahman

Torrefaction of densified empty fruit bunches with addition of plastics waste

ABSTRACT The techniques of briquetting and torrefaction were applied to a mixture of pulverized empty fruit bunches (EFB) and shredded high-density polyethylene (HDPE) plastics with a weight ratio of 85:15. The briquettes, produced under controlled conditions, were torrefied at various torrefaction temperatures from 225 to 300°C for 30 min with a constant nitrogen flow rate of 1 L/min. The results indicate that the moisture content is reduced and calorific value is significantly improved due to torrefaction treatment. In addition, the compressive strength of the torrefied briquettes is also enhanced by the torrefaction treatment, thus revealing the important role of HDPE plastics as a good binding agent after the treatment. However, the density of the torrefied briquettes decreased with an increase in temperature. The ash content of the briquettes torrefied at 225 to 275°C can be considered competitive if compared to that of conventional solid fuels (< 5.8%). The physical and combustion properties of the torrefied briquettes are strongly affected by torrefaction temperature and mixture composition. Meanwhile, torrefaction at 300°C is not favourable due to significant physical degradation. HIGHLIGHTS Densification and torrefaction were performed on pulverized EFB. Fixed operating conditions were used to produce all briquettes. Addition of HDPE plastics improves the physical and combustion properties. Torrefaction temperature is the most important parameter. Torrefaction temperature at 300°C is not favourable due to physical destruction.

The potential of hybrid micro-vortex generators to control flow separation of NACA 4415 airfoil in subsonic flow

Boundary layer separation is detrimental to the lift and drag of most aeronautical applications. Many vortex generators (VG), both passive and active have been designed to reduce these drawbacks. This study targets to investigate the effectiveness of hybrid micro-VGs, which combine both active and passive micro-VGs in controlling separation under subsonic conditions. NACA 4415 airfoils installed with passive, active and hybrid micro-VGs each are designed, 3D printed, and tested in a wind tunnel at 26.19 m/s under Re = 2.5x105. The lift and drag measurements from a 3-component force balance prove that hybrid micro-VGs increase lift by up to 21.2%, increase drag by more than 11.3% and improve lift-to-drag ratio by at least 8.6% until up to 33.7%. From this research, it is believed that hybrid micro-VGs are competitive to the performance of active VGs and a better configuration is to be considered to reduce parasitic drag and outstand active VGs.

Dimensional Accuracy Evaluation of Rapid Prototyping Fused Deposition Modeling Process of FDM200mc Machine on Basic Engineering Profiles

The purpose of this research is to study the accuracy of RP FDM Process. This research involves varying two parameters in building up the prototype which is the buildup angle and the sparse for each layer (volume of parts). The varying parameters were used in the FDM process for three types of specimen (profiles) which is the Cube, Cylinder and Pyramid. The varying parameters are the build up angle of 300, 650 and 900 and for the types of sparse, there are three types of sparse used which is Low Density (LD), High Density (HD) and Solid Type. The results of the dimensional accuracy are analyzed by calculating the percentage of difference of the dimensional measurement for the specimen and the actual dimension of it. The lesser difference, the better the dimensional accuracy. The conclusion of this study is the less complicated specimen shape for the FDM process, the more accurate of the dimensional accuracy with the optimum build up angle of 300 or less and the optimum type of sparse of Low Density Type (LD).