Applied Mechanics and Materials Vols. 773-774

Abstract: Diesel engine is an internal combustion engine that uses the high compression pressure to ignite the combustible mixture due to high temperature in the combustion chamber. There were many studies on the fuel-air premixing that resulting from air entrainment which linked to the improvement of exhaust emissions [1][2][3]. The most important issue in diesel combustion is achieving sufficient rapid mixing between the injected fuel and the air in cylinder prior to ignition. The oxidation reactions at the end of endothermic period depend on the physical process such as air entrainment, the breakup of the jet spray, and droplets evaporation.

Abstract: The primary function of an electronic control unit (ECU) of an engine is to calculate the amount of fuel to be delivered into the combustion chamber. The injection duration and duty cycle of the injector will be based on several sensors whose signals the ECU will process to ensure the best engine running condition. However, to study new injection and combustion strategies, where such operation is unavailable in standard ECU, a custom-built fuel injection control system need to be made. This paper describes the development of a fuel injector signal controller, which is being used for internal combustion engine experiment or for the evaluation of any fuel injector static flow rate. Herewith a new term Injector-Volume Ratio (IVR) was introduced to assist the development process. Using the custom-built fuel injection controller, the static flow rate of an injector for a single cylinder 125cc motorcycle engine was determined in accordance to SAEJ1832. From the experiment, the IVR value is proven useful in choosing the right size of a fuel injector to fit any specified engine displacement of a spark ignition engine.

Abstract: The increase of industrial activities and motor vehicles globally causes rise demands in fossil fuel as energy sources. Since fossil fuel is non-renewable energy, many researches have been conducted to reduce the reliance to this fossil fuel. In conjunction, the number of waste plastic and tires around the world is increasing as a result of modern application and increasing number of motor vehicle. This type of waste is hard to decays and commonly dumped onto open landfills. Utilization of waste tires and plastics can produce alternative fuel that potentially can be used in diesel engine. In this paper, the combustion characteristics of two waste source fuels known as waste plastic disposal fuel (WPDF) and tire disposal fuel (TDF) are discussed. The combustion characteristics of both fuels are compared to diesel fuel. WPDF and TDF used in this experiment are pure concentrated and not blended with diesel fuel. The experiment is conducted using single cylinder YANMAR TF120M diesel engine. The engine is operated at constant load at 20 Nm and variable speed ranged from 1200 rpm to 2400 rpm. The combustion characteristics that discussed in this paper are ignition delay and peak pressure. Both characteristic are measured at two engine speed region which is low speed (1200 rpm) and high speed (2100 rpm). From the results obtained, it can be observed that WPDF has comparable ignition delay compared to diesel fuel while TDF has longest ignition delay compared to WPDF and diesel fuel. TDF also produce highest peak pressure compared to other tested fuels. Moreover, TDF is not suitable for high speed application since it cause backfire when engine speed reach 2200 rpm.

Abstract: Environment and energy problems over the world have motivated researchers to develop energy systems more sustainable, having as one of the possible alternative the use of solar energy as source for cooling systems. Adsorption refrigeration systems are regarded as environmentally friendly alternatives to conventional vapour compression refrigeration systems, since they can use refrigerants that do not contribute to ozone layer depletion and global warming. In this paper a performance comparison between a solar continuous adsorption cooling system without mass recovery process and solar continuous adsorption cooling system with mass recovery process is carried out. Silica-Gel as adsorbent and water as refrigerant are selected. The results show that the adsorption refrigeration machine driven by solar energy can operate effectively during four months and is able to produce cold continuously along the 24 hours of the day. The importance of the mass recovery is proved in this study by increasing the coefficient of performance and the cooling capacity produced. For the same cooling capacity produced, the required number of solar collectors with mass recovery system is lower than the required number of solar collectors in the case of the refrigeration unit without mass recovery. For the same cooling capacity the system with mass recovery process allowed lower generation temperature.

Abstract: Fuel injection system is widely used in the field of burner system nowadays. Spray nozzles having various operating conditions depends on the design of nozzle and it is precision components designed to perform very specific spray characteristics under specific conditions. This review paper focuses on spray characteristics, effects of geometry of injector, influence of fuel and hole shaped nozzle with cylindrical and conical holes on spray characteristics. The parameters were discussed based on an overview of the research in the field of simulations with nozzle shaped injectors. A massive majority researcher reported that conical nozzle hole is better due to it contributed suppression of cavitation in nozzle hole, slowed down primary breakup process and thus produced larger spray droplets, high spray penetration.

Abstract: Tin doped zinc oxide (Sn:ZnO) thin films were prepared on glass substrates via sol-gel dip-coating technique starting from zinc acetate dehydrate, (CH₃CO₂)₂Zn⋅2H₂O and tin chloride, SnCl₂. The consequences of various Sn doping on the behavior of the film was investigated. The atomic percentages of dopant in ZnO-based solution were [Sn⁴⁺]/[Zn²⁺] which is between 0% and 4%. The thin films were characterized using Field Emission Scanning Electron Microscope (FESEM) and UV-Vis-NIR spectrophotometer.

Abstract: The <111>-Cu₂O/<0001>-ZnO photovoltaic (PV) device has been constructed by a electrodeposition f Cu₂O layer followed by a photon-assisted electrochemical reaction in aqueous solutions, and the effect of the insertion of the TiO₂ layer prepared by a sol-gel technique on the photovoltaic performance was investigated. The structural, optical, and electrical characterizations were carried out with XRD, FE-SEM, UV-Vis-NIR spectrophotometer, and solar simulator. The performance of AZO/<0001>-ZnO/TiO₂/<111>-Cu₂O PV-devices changed depending on the preparation condition for the TiO₂ layer, and the short-circuit current density of 4.86 mAcm^-2 has been obtained for the PV device prepared under optimized condition.

Abstract: In this work, seeded porous silicon (PSi) was used as a substrate in the growth of ZnO nanostructures. PSi was prepared by electrochemical etching method. ZnO thin films as seeded were deposited via sol-gel spin coating method. ZnO nanostructures were grown on seeded PSi using hydrothermal immersion method. In order to study the effect of post-heat treatment on the substrate, post annealing temperature were varied in the range of 300 to 700 °C. The FESEM results shows ZnO thin film composed of nanoparticles were distributed over the PSi surface. Based on AFM characterization, the smoothest surface was produced at post annealing temperature of 500 °C. There are two different peaks appeared in PL characterization. The peak in near-UV range is belonging to ZnO thin films while a broad peak in visible range can be attributed to ZnO defects and PSi surface. In addition, FESEM, XRD and PL were used to characterize the ZnO nanostructures. The FESEM results revealed ZnO nano-flower were successfully grown on seeded PSi. Hexagonal wurtzite of ZnO with dominated by the plane (100), (002), and (101) was found by XRD characterization. Two different peaks in UV range and visible range can be attributed to ZnO nano-flower and various defects of ZnO, respectively.

Abstract: This study demonstrates the fabrication of nanostructured FTO by hydrothermal method. It was directly synthesized on FTO glass substrate by using pentahydrated stannic chloride (SnCl₄.5H₂O) and ammonium fluoride (NH₄F) as precursors. Different synthesis time was applied which were 5h, 10h and 24h. The characteristics of nanostructured FTO were investigated via field emission scanning electron microscopy (FESEM), two-point probe current-voltage test and ultraviolet visible spectrometer (UV-Vis). The FESEM images revealed the growth of nanosized particles layer on the FTO substrate. The electrical properties studied have shown a degeneration of conductivity as the thickness of nanostructured layer increased. UV-Vis results showed the decrement of transmittance as the time duration increased. It was revealed through FESEM characterization that the nanostructured FTO can be improved by using dibutyltin diacetate (DBTA) as a precursor.

Abstract: An aqueous solution was prepared by mixing the copper(II) sulfate pentahydrate (CuSO₄), lactic acid, sodium hydroxide (NaOH) and de-ionized (DI) water. Direct deposition of copper(II) oxide (CuO) nanostructures films on glass substrates was achieved by a simple, inexpensive and one-step chemical bath deposition method. The pH of the solution was varied at 11.7, 12.0, 12.3 and 12.6 and immersed at low temperature (90 °C). The influences of the pH solution towards the surface topography, morphology and thickness were investigated by a field emission scanning electron microscopy (FESEM), an atomic force microscope (AFM) and a surface profiler. Meanwhile, an X-ray diffractometer (XRD) was used to examine the structural properties of CuO films. The optical properties were measured by a UV-Vis spectroscopy. It was found that the grain size of the films decreases and the surface becomes smoother and more uniform by increasing the pH solution. The CuO nanostructures have high crystallinity with monoclinic structure which is preferentially grown along ( ) and (200) directions. Therefore, the film has great potential for gas sensor device.