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Performance and electromagnetic interference mitigation of DC-DC converter connected to photovoltaic panel
(2019-11-01)
Jettanasen, C.
;
Pothisarn, C.
Renewable energy has been rapidly increased in terms of installed capacity. However, the electronic components inside such a system can cause a serious threat such as Electromagnetic Interference (EMI) to nearby sensitive devices/equipment. This paper aims to study on performance of DC-DC boost converter connected to photovoltaic panel and how to reduce EMI emissions issued in the system. A passive EMI low-pass filtering is one of various mitigation techniques. The designed converter connected to photovoltaic panel and EMI filter are tested in both simulation software and field testing by using EN55022 standard as a reference.
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Electrochemical performance assessment of low-temperature solid oxide fuel cell with YSZ-based and SDC-based electrolytes
(2018-01-01)
Saebea, Dang
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Authayanun, Suthida
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Patcharavorachot, Yaneeporn
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Chatrattanawet, Narissara
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Arpornwichanop, Amornchai
In this work, solid oxide fuel cells (SOFCs) based on different electrolytes, i.e., the yttria-stabilized zirconia (YSZ) and the samaria-doped ceria (SDC), were investigated to study their performances at low-temperature operation. The predicted performance of both SOFCs was validated with the experimental results. The verified models were implemented to study the impact of operating conditions, i.e., cell temperature, pressure, thicknesses of cathode, anode, and electrolyte, on their performances. The decrease in the operating temperature from intermediate range (800–900 °C) to low range (550–650 °C) has a considerable effect on the performance of the YSZ-based SOFC as conventional type, which dropped from 0.67–1.40 W/cm2 to 0.027–0.13 W/cm2. Under the low operating temperature range, the performance of SDC-based SOFC was superior to that of the YSZ-based SOFC, due to the lower ohmic loss. Nevertheless, the SDC-based SOFC has higher concentration overpotentials than the YSZ-based SOFC. The concentration overpotentials of the SDC-based SOFC can be reduced by the thinner anode and cathode thicknesses. In addition, the SDC-based SOFC at low operating temperature with the pressurized operation could significantly improve its power density, about 20% at 2 bar, which was close to that of YSZ-based SOFC at intermediate temperature of 800 °C.
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Parametric analysis of a circulating fluidized bed biomass gasifier for hydrogen production
(2015-03-15)
Chutichai, Bhawasut
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Patcharavorachot, Yaneeporn
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Assabumrungrat, Suttichai
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Arpornwichanop, Amornchai
Biomass is considered a potential energy source which can be efficiently converted to useful gaseous products via a gasification process. Circulating fluidized bed (CFB) gasifiers have attracted significant attention due to their high reaction rates and thermal efficiency. This study aims to investigate the CFB biomass gasification process to generate H<inf>2</inf>-rich synthesis gas. A process simulator is used to analyze the gasifier performance by assuming that the gasification is fast and reach equilibrium. Parametric analysis of the CFB gasifier shows that steam gasification generates the synthesis gas attained the highest H<inf>2</inf> content (50-65vol.%) and the highest product gas quality (higher heating value, HHV=10-13MJ/Nm3) at operating temperatures approximately 650-700°C. High-temperature steam cannot provide enough energy for the gasifier, reducing the gross cold gas efficiency of this process to only 16%. The biomass air-steam gasification process is investigated while avoiding high energy consumption, but less H<inf>2</inf> is produced under these conditions.
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Evaluation of an integrated methane autothermal reforming and high-temperature proton exchange membrane fuel cell system
(2015-02-01)
Authayanun, Suthida
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Saebea, Dang
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Patcharavorachot, Yaneeporn
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Arpornwichanop, Amornchai
The aim of this study was to investigate the performance and efficiency of an integrated autothermal reforming and HT-PEMFC (high-temperature proton exchange membrane fuel cell) system fueled by methane. Effect of the inclusion of a CO (carbon monoxide) removal process on the integrated HT-PEMFC system was considered. An increase in the S/C (steam-to-carbon) ratio and the reformer temperature can enhance the hydrogen fraction while the CO formation reduces with increasing S/C ratio. The fuel processor efficiency of the methane autothermal reformer with a WGS (water gas shift reactor) reactor, as the CO removal process, is higher than that without a WGS reactor. A higher fuel processor efficiency can be obtained when the feed of the autothermal reformer is preheated to the reformer temperature. Regarding the cell performance, the reformate gas from the methane reformer operated at T<inf>in</inf>=T<inf>R</inf> and with a high S/C ratio is suitable for the HT-PEMFC system without a WGS reactor. When considering the HT-PEMFC system with a WGS reactor, the CO poisoning has less significant impact on the cell performance and the system can be operated over a broader range to minimize the required total active area. A WGS reactor is necessary for the methane autothermal reforming and HT-PEMFC integrated system with regard to the system efficiency.
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Performance analysis of maximum power transfer in piezoelectric energy harvesting
(2015-01-01)
Songsukthawan, P.
;
Jettanasen, C.
Using piezoelectric materials to harvest energy from ambient vibrations to low power required systems such as wireless and sensor for purpose of non-battery utilization, which leads to reduce production of global warming gases, has become increasingly interested. Due to rather low power output of the piezoelectric transducer and relatively high cost per watt of piezoelectric materials, simulation and performance analysis to find maximum power point of the variation of its parameters are considered. This paper presents the modeling of Lead Zirconate Titanate (PZT) employed in low frequency application using mechanical force and simulated in Capture OrCAD environment. The parametric studies are also carried out in order to identify the point that provides the highest performance allowing making decision for choosing proper piezoelectric material characteristics to match to specific tasks.
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Effect of different fuel options on performance of high-temperature PEMFC (proton exchange membrane fuel cell) systems
(2014-04-15)
Authayanun, Suthida
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Saebea, Dang
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Patcharavorachot, Yaneeporn
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Arpornwichanop, Amornchai
High-temperature proton exchange membrane fuel cells (HT-PEMFCs) have received substantial attention due to their high CO (carbon monoxide) tolerance and simplified water management. The hydrogen and CO fractions affect the HT-PEMFC performance and different fuel sources for hydrogen production result in different product gas compositions. Therefore, the aim of this study is to investigate the theoretical performance of HT-PEMFCs fueled by the reformate gas derived from various fuel options (i.e., methane, methanol, ethanol, and glycerol). Effects of fuel types and CO poisoning on the HT-PEMFC performance are analyzed. Furthermore, the necessity of a water-gas shift (WGS) reactor as a CO removal unit for pretreating the reformate gas is investigated for each fuel type. The methane steam reforming shows the highest possibility of CO formation, whereas the methanol steam reforming produces the lowest quantity of CO in the reformate gas. The methane fuel processing gives the maximum fraction of hydrogen (≈0.79) when the WGS reactor is included. The most suitable fuel is the one with the lowest CO poisoning effect and the maximum fuel cell performance. It is found that the HT-PEMFC system fueled by methanol without the WGS reactor and methane with WGS reactor shows the highest system efficiency (≈50%). © 2014 Elsevier Ltd.
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Neural network hybrid model of a direct internal reforming solid oxide fuel cell
(2012-02-01)
Chaichana, Kattiyapon
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Patcharavorachot, Yaneeporn
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Chutichai, Bhawasut
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Saebea, Dang
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Assabumrungrat, Suttichai
A mathematical model is an important tool for analysis and design of fuel cell stacks and systems. In general, the complete description of fuel cells requires an electrochemical model to predict their electrical characteristics, i.e., cell voltage and current density. However, obtaining the electrochemical model is quite a difficult and complicated task as it involves various operational, structural and electrochemical reaction parameters. In this study, a neural network model was first proposed to predict the electrochemical characteristics of solid oxide fuel cell (SOFC). Various NN structures were trained based on the back-propagation feed-forward approach. The results showed that the NN with optimal structure reliably provides a good estimation of fuel cell electrical characteristics. Then, a neural network hybrid model of a direct internal reforming SOFC, combining mass conservation equations with the NN model, was developed to determine the distributions of gaseous components in fuel and air channels of SOFC as well as the performance of the SOFC in terms of power density and fuel cell efficiency. The effects of various key parameters, e.g., temperature, pressure, steam to carbon ratio, degree of pre-reforming, and inlet fuel flow rate on the SOFC performance under steady-state and isothermal conditions were also investigated. A combination of the first principle model and NN presents a significant advantage of predicting the SOFC performance with accuracy and less computational time. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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Route reservation in ad hoc wireless networks
(2007-01-01)
Panichpapiboon, Sooksan
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Ferrari, Gianluigi
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Wisitpongphan, Nawaporn
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Tonguz, Ozan K.
This paper investigates whether and when route reservation-based (RB) communication can yield better delay performance than non-reservation-based (NRB) communication in ad hoc wireless networks. In addition to posing this fundamental question, the requirements (in terms of route discovery, medium access control (MAC) protocol, and pipelining, etc.) for making RB switching superior to NRB switching are also identified. A novel analytical framework is developed and the network performance under both RB and NRB schemes is quantified. It is shown that if the aforementioned requirements are met, then RB schemes can indeed yield better delay performance than NRB schemes. This advantage, however, comes at the expense of lower throughput and goodput compared to NRB schemes. © 2007 IEEE.

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