Zolkafle Buntat

Ozone generation using atmospheric pressure glow discharge in air

This paper presents results from a study into the generation of ozone by a stable atmospheric glow discharge, using dry air as the feeding gas for ozone generation. The power supply is 50 Hz ac, with the use of a perforated aluminium sheet for the electrodes and soda lime glass as a dielectric layer in a parallel-plate configuration, stabilizing the generation process and enabling ozone to be produced. The stable glow discharge spreads uniformly at a gas breakdown voltage below 4.8 kV and requires only 330 mW discharge power, with a limitation of 3 mm on the maximum gap spacing for the dry air. With the technique providing a high collision rate between the electrons and gas molecules during the discharge process, a high ozone yield is obtained. An analysis of the effect on the production rate of parameters such as the input voltage, gas flow rate and reaction chamber dimensions resulted in a highest efficiency of production of almost 350 g kWh−1 and confirms its potential as an important ozone generation technology.

Analytical investigations of gas-sensor using methane decomposition system

AbstractThis paper reports on a set of experiments designed to develop a workable gas sensor prototype using an electronic system with methane. The current is found to be sensitive to the presence of methane gas, which is a conduit for a variety of gas sensors. The sensitivity is shown to depend on pointed or broad electrode configurations. Scanning electron microscopy images show the area of conductance that determines the quality of the electrodes in three configurations. Data processing is performed with a support vector regression algorithm in conjunction with statistical analysis for error and quality control. The reported results can be adapted to a broad range of industrial applications for enhanced productivity, safety, innovation, data processing, and overall total quality management.

Analytical calculation of sensing parameters on carbon nanotube based gas sensors

Carbon Nanotubes (CNTs) are generally nano-scale tubes comprising a network of carbon atoms in a cylindrical setting that compared with silicon counterparts present outstanding characteristics such as high mechanical strength, high sensing capability and large surface-to-volume ratio. These characteristics, in addition to the fact that CNTs experience changes in their electrical conductance when exposed to different gases, make them appropriate candidates for use in sensing/measuring applications such as gas detection devices. In this research, a model for a Field Effect Transistor (FET)-based structure has been developed as a platform for a gas detection sensor in which the CNT conductance change resulting from the chemical reaction between NH3 and CNT has been employed to model the sensing mechanism with proposed sensing parameters. The research implements the same FET-based structure as in the work of Peng et al. on nanotube-based NH3 gas detection. With respect to this conductance change, the I–V characteristic of the CNT is investigated. Finally, a comparative study shows satisfactory agreement between the proposed model and the experimental data from the mentioned research.

Application of dimensional analysis to ozone production by pulsed streamer discharge in oxygen

This paper describes the use of dimensional analysis in investigating the effects of the electrical and the discharge configuration parameters on ozone production in oxygen, by means of a pulsed streamer discharge. Ozone destruction factors are taken into account in the model, and predicted results are shown to be in good agreement with experimental findings.

The development of ozone generation with low power consumption

This paper proposed the use of low power and low cost high frequency, high voltage resonant inverter as power supply to produce ozone gas at normal atmospheric pressure and ambient temperature. The modified class E resonant power converter is studied based on modified boost converter. The advantage of resonance phenomena used to convert the square waveform voltage input into sinusoidal output voltage in high voltage and high frequency. The model of the ozone chamber is developed using the RLC circuit. This basic RLC resonance tank circuit is used to determine the resonance frequency for inverter as a power supply to ozone chamber. It is also investigated the use of class E resonant when it is operated below resonant converter and act as pulse converter to supply the ozone chamber. As the result, the class E resonant converter has successfully produced maximum 2.8 kVpp, 8.66 kHz as resonant converter consumed of 8.74 Watt to produce 11,300 µg/m3 ozone. As the pulse power supply, the class E circuit produced 2.8 kVpp at 6.2 kHz, 18.3 watt to generate 5,900 µg/m3 Ozone. This low power converter and simple ozone chamber has a possibility to be developed as ozone generator system in compact form for residential application.

Prediction of salt contamination on high voltage insulators in rainy season using regression technique

The severity of contamination on the high voltage insulator surfaces is the significant factor in determining the level of outdoor insulation and in choosing the types of insulators. In the equatorial region, the most dangerous kind of contamination is salt contamination. A regression technique has been used to develop a modified equivalent salt deposit density (ESDD) mathematical model with respect to meteorological conditions. This model provides a useful way for predicting contamination level and for determining frequency of washing the insulators in a given contaminated area.

Silicene and graphene nano materials in gas sensing mechanism

Silicene, the Si analogue of graphene, has recently extended the short list of existing two-dimensional (2D) atomic crystals. There are many remarkable electrical properties as well as unique thermal conductivities associated with graphene and silicene making them perfect materials that possess great potential to replace and provide an even better performance than silicon in future generation semiconductor devices. It is expected that novel devices developed with these will be much faster and smaller in size than their contemporary counterparts. Although graphene and silicene display different electrical conductivity behavior, their carrier concentration has similar behavior. The current–voltage characteristics of silicene/graphene field effect transistors (FETs) have been demonstrated at different operating temperatures under the flow of different NH3 gas concentrations. It was found that in similar conditions, the suggested model for a gas sensor based on graphene shows higher electrical conductivity compared to silicene.

A New Type of Planar Chamber for High Frequency Ozone Generator System

This paper proposes a new type of planar chamber ozone generation operated at atmospheric pressure, ambient temperature and high frequency. The chamber was constructed in planar type with easy adjustment using simple filler material and arrangement for different type of electrodes. A prototype was developed based on study to find the most effective geometrical electrode shape and dielectric material to produce micro-discharges without additional discharge gas, low pressure and temperature.. The works were initially carried out by theoretical analysis and finite element simulations to find the best geometrical shape for the electrode and to prove theoretical prediction, the experimental works were set up to determine the preferable dielectric to be used along with the electrode. Finally, the best combination was revealed by using muscovite mica and aluminium mesh on copper plate to start generating ozone at 785 Volt and 30 kHz. This planar prototype chamber successfully delivered the highest ozone yield more than 3000 ppm and 120 g/kWh. Due to the simplicity and low cost design, this planar chamber can be suitably used for portable and home appliance.

Silent discharge ozonizer for colour removal of treated palm oil mill effluent using a simple high frequency resonant power converter

Palm oil agricultural and industry activities generate a great amount of by product, known as palm oil mills effluent (POME). The treatment conducted using membrane bioreactor has successfully removed the heavy organic component of POME but the water that remains still contain colour as its by product. This paper proposed the use of a simple silent discharge ozonizer in colour removal of treated palm oil mill effluent (POME). The ozonizer chamber was developed from a simple planar metal dielectric barrier discharge construction. A simple high frequency power converter as power supply to the chamber was designed based on resonance phenomena. This power supply converted a direct current low voltage input into high frequency and high sinusoidal voltage output. This high voltage created micro electrical discharges inside chamber to generate ozone from oxygen molecules. At normal atmospheric pressure and ambient temperature, this ozonizer produced ozone concentration up to 1800 ppm. Ozone in a certain concentration was injected into the treated POME water through a diffuser for several minutes. As the result, the colour of treated POME water has successfully changed from 100 mg/l Pt. Co into 40 mg/l Pt. Co or lower. Visually, water colour below 40mg/l Pt. Co is considered clear. Extended the time of ozone treatment upto 15 minute has successfully reach colour abatement below 15 mL/l Pt. Co which accords to World Health Organiation (WHO) recommendation for Colour in drinking water.

Escherichia coli bacteria detection by using graphene-based biosensor

Graphene is an allotrope of carbon with two-dimensional (2D) monolayer honeycombs. A larger detection area and higher sensitivity can be provided by graphene-based nanosenor because of its 2D structure. In addition, owing to its special characteristics, including electrical, optical and physical properties, graphene is known as a more suitable candidate compared to other materials used in the sensor application. A novel model employing a field-effect transistor structure using graphene is proposed and the current-voltage (I-V) characteristics of graphene are employed to model the sensing mechanism. This biosensor can detect Escherichia coli (E. coli) bacteria, providing high levels of sensitivity. It is observed that the graphene device experiences a drastic increase in conductance when exposed to E. coli bacteria at 0-10(5) cfu/ml concentration. The simple, fast response and high sensitivity of this nanoelectronic biosensor make it a suitable device in screening and functional studies of antibacterial drugs and an ideal high-throughput platform which can detect any pathogenic bacteria. Artificial neural network and support vector regression algorithms have also been used to provide other models for the I-V characteristic. A satisfactory agreement has been presented by comparison between the proposed models with the experimental data.