PowerPoint Presentation

[Audio] Assalamualaikum and hello everybody. My name is Zulkifly Aziz and I am a fourth year PhD student in the faculty of electrical and electronics engineering, and today I am going to be talking about my research on the application of wireless power transfer to turn petrochemical wastewater into hydrogen..

[Audio] Increasing consumption of oil in modern society has led to more oil and oil refinery waste generation. The oil processing wastewater and waste has high concentrations of aliphatic, and aromatic petroleum hydrocarbons. Direct discharge of this will affect plants and aquatic life of surface and ground water sources.

[Audio] Treatments are becoming a rising challenge, threatened by the presence of contaminants of emerging concern (CECs) in wastewater effluents. CECs include phenols, sulfur, and hydrocarbons from petrochemical wastewater, pharmaceuticals, personal care products, hormones, and other industrial chemicals. The quality of water is quickly becoming a worldwide issue of major importance, more so because more than one third of the world's supply of renewable freshwater is used for agricultural, industrial and domestic activities which introduces a broad spectrum of contaminants ranging from synthetic to natural chemicals..

[Audio] Chemical treatment, biological anaerobic, anoxic, and aerobic digestion or a combination of each other, have been implemented to treat petrochemical wastewater. But stringent regulations have motivated researchers to design advanced treatment facilities such as photoreforming, to give high treatment efficiency, low maintenance, footprint, and operational costs..

[Audio] Recently, an inductive wireless power transfer has been proposed to power mobile LED-based light emitters to overcome the issue of poor light distribution inside the photoreactor. Inductive wireless power transfer is defined as the transfer of power over a short distance, usually less than a meter, without the use of cabling or wire. This is possible if both the transmitting and the pickup sides are resonated at the same frequency..

[Audio] But, before we get to the idea of how these two concepts are synergized, let us explore what are the problems associated with the conventional photoreforming system which could be potentially fixed by inductive wireless power transfer..

[Audio] The immobilization strategy severely limits the light penetration depth through the dense catalytic layer, limiting the photocatalytic activity to the thin region close to the surface of the photocatalytic layer..

[Audio] While suspended solids system brings the issue of light attenuation caused by light absorption and scattering..

[Audio] A spinning disk reactor is introduced to improve mass transfer over a large irradiated area, but the thin layer of liquid film will only permit low throughput and the large disk rotor blocks the passage of light and reduces the total irradiated area to only 42 % of the total reactor volume..

[Audio] In externally lit irradiation system using high-intensity discharge Xenon lamp, much of the energy is lost due to the large air gap between the light source and the reaction medium while some of the energy is lost as heat..

[Audio] An externally lit system using an optical fiber as the light guide has been proposed. In this system, the fiber cladding is removed, and the bare fiber is coated with a photocatalytic layer having higher refractive index than the fiber core so that part of the light is refracted off the fiber and absorbed by the photocatalytic layer, while the rest is reflected down the fiber strand. The problem with this arrangement is nonuniform coating. Light is lost through noncoated opening on the fiber wall. Poor adhesion of the photocatalytic layer introduces peeling which contaminated the solution..

[Audio] Instead of using an artificial light source, solar system has been proposed. But this arrangement is dependent on sunlight will require tracking of the sun to maximize the energy harnessed for the photocatalytic activity. In addition, the system is weather dependent and may not be economical in location where the position of the sun varies with season. For the system to work, precise geometry of the parabolic mirror is required so that gathered photon are directed toward the reactor..

[Audio] So the goal in the study is to implement an inductive wireless power transfer in a photoreforming system so the issues that have been discussed earlier could be addressed objectively. The goal is met by addressing three research objectives..

[Audio] Finite element method and statistical analysis are employed to simulate the magnetic field density inside a cylindrical column as a function of coil diameter for a given reactor height. These figures here show the flux deviation inside a cylindrical column is dependent on coil diameter and height of cylinder..

[Audio] A linear dependency is observed between the coil diameter and the height of the cylindrical reactor as evident from the chart. Hence, a circular coil having a diameter of 15 cm is required to produce a uniform field inside a 60 cm tall cylindrical column.

[Audio] Using the Biot-Savart law to analytically solved for the magnetic field density induced by a loop of current carrying wire, the normalized magnetic field density plotted against the distance of separation between the 2 coils shows the flux deviation is almost uniform even when the coils are spaced at 1.5R apart, without significant loss in magnetic field intensity with respect to the single coil configuration. This shows that at 1.5R, the radius of uniform distribution extends up to (-0.75,+0.75) compared to (-0.5,+0.5) at normal Helmholtz separation of R..

[Audio] Using the simulated results, a triple Helmholtz coils pairs with an optimized coil diameter and spacing are fabricated. The coil fixtured are designed in FUSION and 3D-printed using polylactic acid filament. All the fixtures are secured with nylon bolts and nuts..

[Audio] The field uniformity are gauged by calculating the mutual inductance profile along the central axis of the transmit coil. The simulated results are then verified with experimental measurement. Ferrite core are used in the receiver to improve coupling and mutual inductance. In addition, the tip of the ferrite core are shaped to explore the effect of surface area on the flux density. The mutual inductance plot here showed the receiver with the rounded-tip core performed slightly better than the flat-tip core when the flux lines were curved at the edges of the coil. Along the axis of the cylinder, the difference were too small, except near the end of the cylinders where the flat-tip receiver appears to performed slightly better because the straight flux lines along the central axis are confined over a smaller area which enhances the flux density. The results here showed a uniform magnetic field distribution along the central column, and the experimental values agreed well with the theoretical values..

[Audio] The field uniformity is also gauged by measuring the coupling coefficient profile along the central axis of the transmit coil. The coupling coefficient varied between 0.01-0.027, slightly better than the typical value of 0.02 observed in other loosely coupled inductive system. For this application, the size of the receiving coil is 15 times smaller than the diameter of the transmit coil, so the result obtained is better than expected. Again, the results here showed a uniform magnetic field distribution along the central column, and the experimental values agreed well with the theoretical values..

[Audio] Being a highly nonlinear, the output waveform of the class-E amplifier is dependent on several parameters which complicates the design process. Design values such as input voltage, switching frequency, and duty ratio of the gate signal are fixed to simplify the design and the resonance parameters are then simulated in LTspice to determine the value of the inductance and capacitance required for the resonant tank..

[Audio] This is achieved by varying the value of the filter network while observing the output voltage across the MOSFET device..

[Audio] The circuit diagram and layout are designed in easyEDA and sent to the manufacturing lab in China for fabrication..

[Audio] The result is then experimentally verified by observing the shape of the voltage waveform across the MOSFET device while the switching frequency is varied slightly to achieve soft switching and perfect tuning..

[Audio] In conventional class-E amplifier design, the field coil is part of the filter circuit. While this arrangement saves space and components, it causes problem when applied in photoreforming application. Mainly because the field coil designed for this system is a highly reactive load, so simultaneous presence of high voltage and current in the field coil will produce electrical arching and introduce fire hazard, not to mention electrocuting any personnel who might venture too close to the field coil..

[Audio] To address this issue, an output transformer is used to isolate the highly reactive field coil from the LC tank of the class-E switching inverter circuitry. Note that the LC tank is now part of the circuitry and secured onto the printed circuit board. The field coil is now isolated from the circuitry via the output transformer. In the event of upscaling or downscaling, changes to the geometry of the reactor can be easily accommodated by changing the turn ratio of the output transformer without changing any of the components on the printed circuit board..

[Audio] Finally, the proposed electrical circuit diagram is turned into a series of equivalent circuits using circuit analysis..

[Audio] From circuit analysis, an equation is derived to calculate the power transfer efficiency for the proposed wireless transfer link..

[Audio] To verify the accuracy of the power transfer efficiency equations derived previously, a measurement setup is devised as illustrated in the figure above. A nano vector network analyzer is used to measure the S-parameters which are then converted into Z-parameters in MATLAB..

[Audio] The measured Z-parameters are then plugged into the following set of equations to obtain the power transfer efficiency of the wireless transmit link..

[Audio] A good agreement is obtained between the proposed theoretical equation and the measured power transfer efficiency of the wireless transfer link..

[Audio] The schematic of the proposed receiver is illustrated in the inset diagram. The resonant tank consist of an inductor with optimized number of turns and a polypropylene capacitor in parallel arrangement. Parallel arrangement will ensure that the resonant tank behave as a voltage source for the LED. On the other hand, a series configuration will not work for this photoreforming application because it introduces a series resistance into the circuitry at resonance. This series resistance will behave like a voltage divider, which limit the amount of voltage supply to the LED. Even if the LED is turned on at all, it would be very dimly lit. Finally, a weight is added to shift the center of gravity toward the bottom of the receiver so it will regain its upright position quickly in the event of collision..

[Audio] The LED is first calibrated prior to its use and the calibration setup is illustrated here. The purpose of this calibration exercise is to measure the intensity of the LED against the dissipated power since this information is not available in the manufacture's datasheet. Knowing this information, operating the LED in the nonlinear region can be avoided to minimize power being lost as heat..

[Audio] A 12 by 5 mm ferrite rod is used in the receiver to increase the coupling strength and boost the induced voltage. An optimized wire length which maximize the quality factor of the receiving coil is implemented. The LED used is type 5050 white LED from Solleds Incorporated, while the ferrite core used is type 3C90 from Ferroxcube with reported initial permeability pf 2300 that is stable up to one megahertz without significant core loss. Enameled copper wire having a diameter of 0.314 mm is used for the coil. To promote buoyancy while maintaining vertical alignment inside the magnetic field of the transmit coil, the density of the light emitter is carefully calibrated. Finally, the receiving coil circuitry is then sealed inside a watertight acrylic ball..

[Audio] The intensity of LED is proportional to the applied power and the product kQ. The coupling coefficient k is enhanced by using a high permeability ferrite core while the quality factor Q is maximized by judicious selection of the turn ratio achieved by measuring the inductance and the equivalent series resistance at each turn of the coil winding. With the kQ product maximized, so does the LED intensity..

[Audio] The plot of LED intensity vs applied power shows that the LED operates linearly when the applied input power is between 50-275 mW. It is evident that the LED operates nonlinearly outside of this region with some of the energy being dissipated as heat across its junction..

[Audio] The optimized number of turns which yields the best Q factor is 50 turns.

[Audio] It has been known that high intensity does not always contribute to chemical reaction in photoreforming due to increased recombination. Hence, the intensity of the LED must be regulated, an issue which has never been addressed before. So the system proposed here are equipped with regulation feature as evident from the graph above where the intensity can be regulated between 70-375 W/m2 by varying the DC supply voltage to the power transmitting unit from 9-18 Volts..

[Audio] We conclude this presentation with the following remarks: Uniform magnetic field distribution inside a 10.6 liter cylindrical column is achieved by designing a triple Helmholtz coil pairs spaced at 1.5R apart. Field uniformity is gauged by numerically calculating the two-dimensional profile of the coupling coefficient and the mutual inductance along the central column and verified to be in good agreement with experimental measurements. A power transmitting unit based on class-E inverter is designed and fabricated. Unlike conventional class-E switching inverter which employs the field coil as part of the filter circuit, the highly reactive field coil is isolated from the inverter circuitry via a toroidal output transformer. Since maximum power delivery to the field coil is achieved by matching the impedance of the field coil while isolating the load from the inverter circuitry, the system is less sensitive to the varying load caused by the presence of multiple receivers. In addition, upscaling and downscaling of the reactor geometry is easily achieved by simple modification to the winding ratio of the output transformer without affecting the inverter circuitry. The wireless coupler achieved a power transfer efficiency of 23.6 %. Calculation of the power transfer efficiency showed a good agreement with the experimental result. An optimized receiver circuitry with parallel LC arrangement is fabricated. Improved coupling is achieved with the use of high permeability ferrite rod while simultaneously optimizing the Q factor optimizes the LED intensity. Finally, the incorporated regulating intensity feature enables fine tuning of the LED intensity to suit the requirement of the photocatalytic system and could potentially eliminate the issue of increased recombination rate at high light intensity. Finally, a video of the multiple light emitters powered by inductive wireless power transfer system is.